WorldWideScience

Sample records for school seismic station

  1. National Seismic Station

    International Nuclear Information System (INIS)

    Stokes, P.A.

    1982-06-01

    The National Seismic Station was developed to meet the needs of regional or worldwide seismic monitoring of underground nuclear explosions to verify compliance with a nuclear test ban treaty. The Station acquires broadband seismic data and transmits it via satellite to a data center. It is capable of unattended operation for periods of at least a year, and will detect any tampering that could result in the transmission of unauthentic seismic data

  2. Moment magnitude determination of local seismic events recorded at selected Polish seismic stations

    Science.gov (United States)

    Wiejacz, Paweł; Wiszniowski, Jan

    2006-03-01

    The paper presents the method of local magnitude determination used at Polish seismic stations to report events originating in one of the four regions of induced seismicity in Poland or its immediate vicinity. The method is based on recalculation of the seismic moment into magnitude, whereas the seismic moment is obtained from spectral analysis. The method has been introduced at Polish seismic stations in the late 1990s but as of yet had not been described in full because magnitude discrepancies have been found between the results of the individual stations. The authors have performed statistics of these differences, provide their explanation and calculate station corrections for each station and each event source region. The limitations of the method are also discussed. The method is found to be a good and reliable method of local magnitude determination provided the limitations are observed and station correction applied.

  3. S. Pellegrino and Brasimone seismic stations

    International Nuclear Information System (INIS)

    Capocecera, P.; Tedeschi, E.; Vitiello, F.

    1988-07-01

    The paper describes the technical features relative to the S. Pellegrino and Brasimone seismic stations. The stations have been modified in order to realize a central data acquisition system; in this way seismic signals are sent to Brasimone Center through telephone pair and are recorded in continuous form. (author)

  4. New Seismic Monitoring Station at Mohawk Ridge, Valles Caldera

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Peter Morse [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-20

    Two new broadband digital seismic stations were installed in the Valles Caldera in 2011 and 2012. The first is located on the summit of Cerros del Abrigo (station code CDAB) and the second is located on the flanks of San Antonio Mountain (station code SAMT). Seismic monitoring stations in the caldera serve multiple purposes. These stations augment and expand the current coverage of the Los Alamos Seismic Network (LASN), which is operated to support seismic and volcanic hazards studies for LANL and northern New Mexico (Figure 1). They also provide unique continuous seismic data within the caldera that can be used for scientific studies of the caldera’s substructure and detection of very small seismic signals that may indicate changes in the current and evolving state of remnant magma that is known to exist beneath the caldera. Since the installation of CDAB and SAMT, several very small earthquakes have already been detected near San Antonio Mountain just west of SAMT (Figure 2). These are the first events to be seen in that area. Caldera stations also improve the detection and epicenter determination quality for larger local earthquakes on the Pajarito Fault System east of the Preserve and the Nacimiento Uplift to the west. These larger earthquakes are a concern to LANL Seismic Hazards assessments and seismic monitoring of the Los Alamos region, including the VCNP, is a DOE requirement. Currently the next closest seismic stations to the caldera are on Pipeline Road (PPR) just west of Los Alamos, and Peralta Ridge (PER) south of the caldera. There is no station coverage near the resurgent dome, Redondo Peak, in the center of the caldera. Filling this “hole” is the highest priority for the next new LASN station. We propose to install this station in 2018 on Mohawk Ridge just east of Redondito, in the same area already occupied by other scientific installations, such as the MCON flux tower operated by UNM.

  5. Burar seismic station: evaluation of seismic performance

    International Nuclear Information System (INIS)

    Ghica, Daniela; Popa, Mihaela

    2005-01-01

    A new seismic monitoring system, the Bucovina Seismic Array (BURAR), has been established since July 2002, in the Northern part of Romania, in a joint effort of the Air Force Technical Applications Center, USA, and the National Institute for Earth Physics (NIEP), Romania. The small-aperture array consists of 10 seismic sensors (9 vertical short-period and one three-component broad band) located in boreholes and distributed in a 5 x 5 km 2 area. At present, the seismic data are continuously recorded by the BURAR and transmitted in real-time to the Romanian National Data Center in Bucharest and National Data Center of the USA, in Florida. Based on the BURAR seismic information gathered at the National Data Center, NIEP (ROM N DC), in the August 2002 - December 2004 time interval, analysis and statistical assessments were performed. Following the preliminary processing of the data, several observations on the global performance of the BURAR system were emphasized. Data investigation showed an excellent efficiency of the BURAR system particularly in detecting teleseismic and regional events. Also, a statistical analysis for the BURAR detection capability of the local Vrancea events was performed in terms of depth and magnitude for the year 2004. The high signal detection capability of the BURAR resulted, generally, in improving the location solutions for the Vrancea seismic events. The location solution accuracy is enhanced when adding BURAR recordings, especially in the case of low magnitude events (recorded by few stations). The location accuracy is increased, both in terms of constraining hypocenter depth and epicentral coordinates. Our analysis certifies the importance of the BURAR system in NIEP efforts to elaborate seismic bulletins. Furthermore, the specific procedures for array data processing (beam forming, f-k analysis) increase significantly the signal-to-noise ratio by summing up the coherent signals from the array components, and ensure a better accuracy

  6. A new seismic station in Romania the Bucovina seismic array

    International Nuclear Information System (INIS)

    Grigore, Adrian; Grecu, Bogdan; Ionescu, Constantin; Ghica, Daniela; Popa, Mihaela; Rizescu, Mihaela

    2002-01-01

    Recently, a new seismic monitoring station, the Bucovina Seismic Array, has been established in the northern part of Romania, in a joint effort of the Air Force Technical Applications Center, USA, and the National Institute for Earth Physics, Romania. The array consists of 10 seismic sensors (9 short-period and one broad band) located in boreholes and distributed in a 5 x 5 km area. On July 24, 2002 the official Opening Ceremony of Bucovina Seismic Array took place in the area near the city of Campulung Moldovenesc in the presence of Romanian Prime Minister, Adrian Nastase. Starting with this date, the new seismic monitoring system became fully operational by continuous recording and transmitting data in real-time to the National Data Center of Romania, in Bucharest and to the National Data Center of USA, in Florida. Bucovina Seismic Array, added to the present Seismic Network, will provide much better seismic monitoring coverage of Romania's territory, on-scale recording for weak-to-strong events, and will contribute to advanced seismological studies on seismic hazard and risk, local effects and microzonation, seismic source physics, Earth structure. (authors)

  7. Background noise model development for seismic stations of KMA

    Science.gov (United States)

    Jeon, Youngsoo

    2010-05-01

    The background noise recorded at seismometer is exist at any seismic signal due to the natural phenomena of the medium which the signal passed through. Reducing the seismic noise is very important to improve the data quality in seismic studies. But, the most important aspect of reducing seismic noise is to find the appropriate place before installing the seismometer. For this reason, NIMR(National Institution of Meteorological Researches) starts to develop a model of standard background noise for the broadband seismic stations of the KMA(Korea Meteorological Administration) using a continuous data set obtained from 13 broadband stations during the period of 2007 and 2008. We also developed the model using short period seismic data from 10 stations at the year of 2009. The method of Mcmara and Buland(2004) is applied to analyse background noise of Korean Peninsula. The fact that borehole seismometer records show low noise level at frequency range greater than 1 Hz compared with that of records at the surface indicate that the cultural noise of inland Korean Peninsula should be considered to process the seismic data set. Reducing Double Frequency peak also should be regarded because the Korean Peninsula surrounded by the seas from eastern, western and southern part. The development of KMA background model shows that the Peterson model(1993) is not applicable to fit the background noise signal generated from Korean Peninsula.

  8. Performance of an island seismic station for recording T-phases

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, J. A., LLNL

    1998-05-01

    As part of the International Monitoring System (IMS) a worldwide hydroacoustic network consisting of 6 hydrophone and 5 island seismic stations has been planned which will monitor for underwater or low altitude atmospheric explosions. Data from this network is to be integrated with other IMS networks monitoring the Comprehensive Nuclear Test-Ban Treaty. The seismic (T-phase) stations are significantly less sensitive than hydrophones to ocean borne acoustic waves. T-phase signal strength at seismic stations depends on the amplitude of the signal in the water column, the hydroacoustic-seismic conversion efficiency, and loss on the seismic portion of the path through the island. In order to understand how these factors influence the performance of T-phase stations seismic and hydroacoustic data are examined from instruments currently deployed on or around Ascension Island in the South Atlantic Ocean. T-phase recordings for the last 3 years have been collected from the GSN seismic station ASCN on Ascension Island. Surrounding the island are 5 hydrophones which are part of the U.S. Air Force Missile Impact Locating System (MILS). Data from this system have been obtained for some of the events observed at ASCN. Four of the hydrophones are located within 30 km of the coast while the fifth instrument is 100 km to the south. Amplitude spectral estimates of the signal-to-noise levels (SNL) are computed and generally peak between 3 and 8 Hz for both the seismometer and hydrophone data. The seismic SNL generally decays to 1 between 10 and 15 Hz while the hydrophone SNL is still large well above 20 Hz. The ratios of the hydrophone-to-seismometer SNL, at their peak in energy, range between 10 and 100 (20-40 dB) unless a hydrophone is partially blocked by the Ascension Island landmass.

  9. Proposed Construction of Boulder Seismic Station Monitoring Sites, Boulder, Wyoming. Environmental Assessment

    Science.gov (United States)

    2009-02-01

    boreholes at the Boulder Seismic Station for research, development, test, and evaluation (RDT&E) as part of the U.S. Nuclear Treaty monitoring...14 LIST OF FIGURES Figure 1. Location of the proposed Boulder Seismic Station, borehole locations and associated buffers...juncture of Spring Creek and Scab Creek Road (Figure 1). Currently, the Boulder Seismic Station has a 13-element array of seismometers on the property

  10. Efforts toward enhancing seismic safety at Kashiwazaki Kariwa Nuclear Power Station

    International Nuclear Information System (INIS)

    Yamashita, Kazuhiko

    2009-01-01

    It has been two years since the Niigata-ken Chuetsu-oki Earthquake (NCOE) occurred in 2007. The earthquake brought a major disaster for Kashiwazaki, Kariwa, and the neighboring areas. First of all, we would like to give condolences to people in the devastated area and to pray for the immediate recovery. Our Kashiwazaki Kariwa Nuclear Power Station located in the same area was naturally caught up in the earthquake. The station was hit by a big tremor more than its intensity assumed to be valid at the station design stage. In spite of unexpected tremor, preventive functions for the station safety worked as expected as it designed. Critical facilities designed as high seismic class were not damaged, though considerable damages were seen in outside-facilities designed as low seismic class. We currently make efforts to inspect and recover damages. While we carefully carry out inspection and assessment to make sure the station integrity, we are also going forward restoration as well as construction for seismic safety enhancement in turn. This report introduces details of the following accounts, these are an outline of guidelines for seismic design evaluation that was revised in 2006, a situation at Kashiwazaki Kariwa Nuclear Power Station in the aftermath of the earthquake, and efforts toward enhancing seismic safety that the Tokyo Electric Power Company (TEPCO) has made since the seismic disaster, and our approach to evaluation of facility integrity. (author)

  11. Background noise spectra of global seismic stations

    Energy Technology Data Exchange (ETDEWEB)

    Wada, M.M.; Claassen, J.P.

    1996-08-01

    Over an extended period of time station noise spectra were collected from various sources for use in estimating the detection and location performance of global networks of seismic stations. As the database of noise spectra enlarged and duplicate entries became available, an effort was mounted to more carefully select station noise spectra while discarding others. This report discusses the methodology and criteria by which the noise spectra were selected. It also identifies and illustrates the station noise spectra which survived the selection process and which currently contribute to the modeling efforts. The resulting catalog of noise statistics not only benefits those who model network performance but also those who wish to select stations on the basis of their noise level as may occur in designing networks or in selecting seismological data for analysis on the basis of station noise level. In view of the various ways by which station noise were estimated by the different contributors, it is advisable that future efforts which predict network performance have available station noise data and spectral estimation methods which are compatible with the statistics underlying seismic noise. This appropriately requires (1) averaging noise over seasonal and/or diurnal cycles, (2) averaging noise over time intervals comparable to those employed by actual detectors, and (3) using logarithmic measures of the noise.

  12. Spectral characteristics of seismic noise using data of Kazakhstan monitoring stations

    International Nuclear Information System (INIS)

    Mikhajlova, N.N.; Komarov, I.I.

    2006-01-01

    Spectral specifications of seismic noise research for PS23-Makanchi, Karatau, Akbulak, AS057-Borovoye and new three-component station AS059-Aktyubinsk was done. Spectral noise density models were obtained for day and night time and spectral density values variation. Noise close to low-level universal noise model is peculiar for all stations, which provides their high efficiency while seismic monitoring. Noise parameters dependence on seismic receivers installation conditions was investigated separately. Based on three stations (Makanchi, Borovoye, and Aktyubinsk), spectral density change features are shown after borehole equipment installation. (author)

  13. Revision of IRIS/IDA Seismic Station Metadata

    Science.gov (United States)

    Xu, W.; Davis, P.; Auerbach, D.; Klimczak, E.

    2017-12-01

    Trustworthy data quality assurance has always been one of the goals of seismic network operators and data management centers. This task is considerably complex and evolving due to the huge quantities as well as the rapidly changing characteristics and complexities of seismic data. Published metadata usually reflect instrument response characteristics and their accuracies, which includes zero frequency sensitivity for both seismometer and data logger as well as other, frequency-dependent elements. In this work, we are mainly focused studying the variation of the seismometer sensitivity with time of IRIS/IDA seismic recording systems with a goal to improve the metadata accuracy for the history of the network. There are several ways to measure the accuracy of seismometer sensitivity for the seismic stations in service. An effective practice recently developed is to collocate a reference seismometer in proximity to verify the in-situ sensors' calibration. For those stations with a secondary broadband seismometer, IRIS' MUSTANG metric computation system introduced a transfer function metric to reflect two sensors' gain ratios in the microseism frequency band. In addition, a simulation approach based on M2 tidal measurements has been proposed and proven to be effective. In this work, we compare and analyze the results from three different methods, and concluded that the collocated-sensor method is most stable and reliable with the minimum uncertainties all the time. However, for epochs without both the collocated sensor and secondary seismometer, we rely on the analysis results from tide method. For the data since 1992 on IDA stations, we computed over 600 revised seismometer sensitivities for all the IRIS/IDA network calibration epochs. Hopefully further revision procedures will help to guarantee that the data is accurately reflected by the metadata of these stations.

  14. OGS improvements in 2012 in running the Northeastern Italy Seismic Network: the Ferrara VBB borehole seismic station

    Science.gov (United States)

    Pesaresi, Damiano; Romanelli, Marco; Barnaba, Carla; Bragato, Pier Luigi; Durì, Giorgio

    2013-04-01

    The Centro di Ricerche Sismologiche (CRS, Seismological Research Center) of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS, Italian National Institute for Oceanography and Experimental Geophysics) in Udine (Italy) after the strong earthquake of magnitude M=6.4 occurred in 1976 in the Italian Friuli-Venezia Giulia region, started to operate the Northeastern Italy Seismic Network: it currently consists of 17 very sensitive broad band and 18 simpler short period seismic stations, all telemetered to and acquired in real time at the OGS-CRS data center in Udine. Real time data exchange agreements in place with other Italian, Slovenian, Austrian and Swiss seismological institutes lead to a total number of about 100 seismic stations acquired in real time, which makes the OGS the reference institute for seismic monitoring of Northeastern Italy. The southwestern edge of the OGS seismic network stands on the Po alluvial basin: earthquake localization and characterization in this area is affected by the presence of soft alluvial deposits. OGS ha already experience in running a local seismic network in high noise conditions making use of borehole installations in the case of the micro-seismicity monitoring of a local gas storage site for a private company. Following the ML=5.9 earthquake that struck the Emilia region around Ferrara in Northern Italy on May 20, 2012 at 02:03:53 UTC, a cooperation of Istituto Nazionale di Geofisica e Vulcanologia, OGS, the Comune di Ferrara and the University of Ferrara lead to the reinstallation of a previously existing very broad band (VBB) borehole seismic station in Ferrara. The aim of the OGS intervention was on one hand to extend its real time seismic monitoring capabilities toward South-West, including Ferrara and its surroundings, and on the other hand to evaluate the seismic response at the site. We will describe improvements in running the Northeastern Italy Seismic Network, including details of the Ferrara VBB

  15. OGS improvements in 2012 in running the North-eastern Italy Seismic Network: the Ferrara VBB borehole seismic station

    Science.gov (United States)

    Pesaresi, D.; Romanelli, M.; Barnaba, C.; Bragato, P. L.; Durì, G.

    2014-07-01

    The Centro di Ricerche Sismologiche (CRS, Seismological Research Centre) of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS, Italian National Institute for Oceanography and Experimental Geophysics) in Udine (Italy) after the strong earthquake of magnitude M=6.4 occurred in 1976 in the Italian Friuli-Venezia Giulia region, started to operate the North-eastern Italy Seismic Network: it currently consists of 17 very sensitive broad band and 18 simpler short period seismic stations, all telemetered to and acquired in real time at the OGS-CRS data centre in Udine. Real time data exchange agreements in place with other Italian, Slovenian, Austrian and Swiss seismological institutes lead to a total number of about 100 seismic stations acquired in real time, which makes the OGS the reference institute for seismic monitoring of North-eastern Italy. The south-western edge of the OGS seismic network (Fig. 1) stands on the Po alluvial basin: earthquake localization and characterization in this area is affected by the presence of soft alluvial deposits. OGS ha already experience in running a local seismic network in high noise conditions making use of borehole installations in the case of the micro-seismicity monitoring of a local gas storage site for a private company. Following the ML = 5.9 earthquake that struck the Emilia region around Ferrara in Northern Italy on 20 May 2012 at 02:03:53 UTC, a cooperation of Istituto Nazionale di Geofisica e Vulcanologia, OGS, the Comune di Ferrara and the University of Ferrara lead to the reinstallation of a previously existing very broad band (VBB) borehole seismic station in Ferrara. The aim of the OGS intervention was on one hand to extend its real time seismic monitoring capabilities toward South-West, including Ferrara and its surroundings, and on the other hand to evaluate the seismic response at the site. We will describe improvements in running the North-eastern Italy Seismic Network, including details of

  16. the Preliminary Research Based on Seismic Signals Generated by Hutubi Transmitting Seismic Station with One Large-volume Airgun Array

    Science.gov (United States)

    Wang, Q.; Su, J.; Wei, Y.; Zhang, W.; Wang, H.; Wang, B.; Ji, Z.

    2017-12-01

    For studying the subsurface structure and its subtle changes, we built the Hutubi transmitting seismic station with one large-volume airgun array at one artificial water pool in the northern segment of Tianshan mountain, where earthquakes occurred frequently. The airgun array consists of six airguns with every airgun capacity of 2000in3, and the artificial water pool with the top diameter of 100m, bottom diameter of 20m and the depth of 18m.We started the regular excitation experiment with the large-volume airgun source every week since June, 2013. Using seismic signals geneated by the Hutubi airgun source, we made the preliminary research on the airgun source, waveform characteristics and the subsurface velocity changes in the northern Tiansh mountain. The results are as follows: The seismic signal exited by the airgun source is characteristic of low-frequency ,and the dominant frequency is in the range of 2 6Hz. The Hutubi transmitting seismic station can continuously generate long-distance detectable and highly repeatable signals, and the correlation coefficient of sigals is greater than 0.95; and the longest propagation distance arrives to 380km, in addition, the 5000-shot stacked sigal using the phase weighted stack technique can be identified in the station, which is about 1300km from the Hutubi transmitting seismic station. Hutubi large-volume airgun source is fitted to detect and monitor the regional-scale subsurface stress state. Applying correlation test method, we measured weak subsurface velocity changes in the northern Tianshan mountain, and found that the several stations, which are within 150km from the the Hutubi transmitting seismic station, appeared 0.1 0.2% relative velocity changes before the Hutubi MS6.2 earthquake on Dec.8, 2016.

  17. Identifying and Correcting Timing Errors at Seismic Stations in and around Iran

    International Nuclear Information System (INIS)

    Syracuse, Ellen Marie; Phillips, William Scott; Maceira, Monica; Begnaud, Michael Lee

    2017-01-01

    A fundamental component of seismic research is the use of phase arrival times, which are central to event location, Earth model development, and phase identification, as well as derived products. Hence, the accuracy of arrival times is crucial. However, errors in the timing of seismic waveforms and the arrival times based on them may go unidentified by the end user, particularly when seismic data are shared between different organizations. Here, we present a method used to analyze travel-time residuals for stations in and around Iran to identify time periods that are likely to contain station timing problems. For the 14 stations with the strongest evidence of timing errors lasting one month or longer, timing corrections are proposed to address the problematic time periods. Finally, two additional stations are identified with incorrect locations in the International Registry of Seismograph Stations, and one is found to have erroneously reported arrival times in 2011.

  18. A report on upgraded seismic monitoring stations in Myanmar: Station performance and site response

    Science.gov (United States)

    Thiam, Hrin Nei; Min Htwe, Yin Myo; Kyaw, Tun Lin; Tun, Pa Pa; Min, Zaw; Htwe, Sun Hninn; Aung, Tin Myo; Lin, Kyaw Kyaw; Aung, Myat Min; De Cristofaro, Jason; Franke, Mathias; Radman, Stefan; Lepiten, Elouie; Wolin, Emily; Hough, Susan E.

    2017-01-01

    Myanmar is in a tectonically complex region between the eastern edge of the Himalayan collision zone and the northern end of the Sunda megathrust. Until recently, earthquake monitoring and research efforts have been hampered by a lack of modern instrumentation and communication infrastructure. In January 2016, a major upgrade of the Myanmar National Seismic Network (MNSN; network code MM) was undertaken to improve earthquake monitoring capability. We installed five permanent broadband and strong‐motion seismic stations and real‐time data telemetry using newly improved cellular networks. Data are telemetered to the MNSN hub in Nay Pyi Taw and archived at the Incorporated Research Institutions for Seismology Data Management Center. We analyzed station noise characteristics and site response using noise and events recorded over the first six months of station operation. Background noise characteristics vary across the array, but indicate that the new stations are performing well. MM stations recorded more than 20 earthquakes of M≥4.5 within Myanmar and its immediate surroundings, including an M 6.8 earthquake located northwest of Mandalay on 13 April 2016 and the Mw 6.8 Chauk event on 24 August 2016. We use this new dataset to calculate horizontal‐to‐vertical spectral ratios, which provide a preliminary characterization of site response of the upgraded MM stations.

  19. Seismic Structure of Perth Basin (Australia) and surroundings from Passive Seismic Deployments

    Science.gov (United States)

    Issa, N.; Saygin, E.; Lumley, D. E.; Hoskin, T. E.

    2016-12-01

    We image the subsurface structure of Perth Basin, Western Australia and surroundings by using ambient seismic noise data from 14 seismic stations recently deployed by University of Western Australia (UWA) and other available permanent stations from Geoscience Australia seismic network and the Australian Seismometers in Schools program. Each of these 14 UWA seismic stations comprises a broadband sensor and a high fidelity 3-component 10 Hz geophone, recording in tandem at 250 Hz and 1000 Hz. The other stations used in this study are equipped with short period and broadband sensors. In addition, one shallow borehole station is operated with eight 3 component geophones at depths of between 2 and 44 m. The network is deployed to characterize natural seismicity in the basin and to try and identify any microseismic activity across Darling Fault Zone (DFZ), bounding the basin to the east. The DFZ stretches to approximately 1000 km north-south in Western Australia, and is one of the longest fault zones on the earth with a limited number of detected earthquakes. We use seismic noise cross- and auto-correlation methods to map seismic velocity perturbations across the basin and the transition from DFZ to the basin. Retrieved Green's functions are stable and show clear dispersed waveforms. Travel times of the surface wave Green's functions from noise cross-correlations are inverted with a two-step probabilistic framework to map the absolute shear wave velocities as a function of depth. The single station auto-correlations from the seismic noise yields P wave reflectivity under each station, marking the major discontinuities. Resulting images show the shear velocity perturbations across the region. We also quantify the variation of ambient seismic noise at different depths in the near surface using the geophones in the shallow borehole array.

  20. Probabilistic seismic hazard assessment for Point Lepreau Generating Station

    Energy Technology Data Exchange (ETDEWEB)

    Mullin, D. [New Brunswick Power Corp., Point Lepreau Generating Station, Lepreau, New Brunswick (Canada); Lavine, A. [AMEC Foster Wheeler Environment and Infrastructure Americas, Oakland, California (United States); Egan, J. [SAGE Engineers, Oakland, California (United States)

    2015-09-15

    A Probabilistic Seismic Hazard Assessment (PSHA) has been performed for the Point Lepreau Generating Station (PLGS). The objective is to provide characterization of the earthquake ground shaking that will be used to evaluate seismic safety. The assessment is based on the current state of knowledge of the informed scientific and engineering community regarding earthquake hazards in the site region, and includes two primary components-a seismic source model and a ground motion model. This paper provides the methodology and results of the PLGS PSHA. The implications of the updated hazard information for site safety are discussed in a separate paper. (author)

  1. Probabilistic seismic hazard assessment for Point Lepreau Generating Station

    Energy Technology Data Exchange (ETDEWEB)

    Mullin, D., E-mail: dmullin@nbpower.com [New Brunswick Power Corporation, Point Lepreau Generating Station, Point Lepreau, NB (Canada); Lavine, A., E-mail: alexis.lavine@amecfw.com [AMEC Foster Wheeler Environment & Infrastructure Americas, Oakland, CA (United States); Egan, J., E-mail: jegan@sageengineers.com [SAGE Engineers, Oakland, CA (United States)

    2015-07-01

    A Probabilistic Seismic Hazard Assessment (PSHA) has been performed for the Point Lepreau Generating Station (PLGS). The objective is to provide characterization of the earthquake ground shaking that will be used to evaluate seismic safety. The assessment is based on the current state of knowledge of the informed scientific and engineering community regarding earthquake hazards in the site region, and includes two primary components--a seismic source model and a ground motion model. This paper provides the methodology and results of the PLGS PSHA. The implications of the updated hazard information for site safety are discussed in a separate paper. (author)

  2. Local seismic activity monitored at King Sejong Station, Antarctica

    OpenAIRE

    Lee,Duk Kee; Kim,Yea Dong; Nam,Sang Heon; Jin,Young Keun

    1998-01-01

    Source location estimation from single station earthquake data collected at King Sejong Station (62°13'3l"N, 58°47'07"W) from 1995 to 1996 provides seismic activity around King Sejong Station. Analysis of local events, less than 1.5°in angular epicentral distance, finds epicenters located near the Shackleton Fracture Zone, the South Shetland Platform, Deception Island, and North Bransfield Basin. Estimated magnitudes range from 2.2 to 4.5 on the Richter scale, averaging 4.0 in North Bransfiel...

  3. The ANSS Station Information System: A Centralized Station Metadata Repository for Populating, Managing and Distributing Seismic Station Metadata

    Science.gov (United States)

    Thomas, V. I.; Yu, E.; Acharya, P.; Jaramillo, J.; Chowdhury, F.

    2015-12-01

    Maintaining and archiving accurate site metadata is critical for seismic network operations. The Advanced National Seismic System (ANSS) Station Information System (SIS) is a repository of seismic network field equipment, equipment response, and other site information. Currently, there are 187 different sensor models and 114 data-logger models in SIS. SIS has a web-based user interface that allows network operators to enter information about seismic equipment and assign response parameters to it. It allows users to log entries for sites, equipment, and data streams. Users can also track when equipment is installed, updated, and/or removed from sites. When seismic equipment configurations change for a site, SIS computes the overall gain of a data channel by combining the response parameters of the underlying hardware components. Users can then distribute this metadata in standardized formats such as FDSN StationXML or dataless SEED. One powerful advantage of SIS is that existing data in the repository can be leveraged: e.g., new instruments can be assigned response parameters from the Incorporated Research Institutions for Seismology (IRIS) Nominal Response Library (NRL), or from a similar instrument already in the inventory, thereby reducing the amount of time needed to determine parameters when new equipment (or models) are introduced into a network. SIS is also useful for managing field equipment that does not produce seismic data (eg power systems, telemetry devices or GPS receivers) and gives the network operator a comprehensive view of site field work. SIS allows users to generate field logs to document activities and inventory at sites. Thus, operators can also use SIS reporting capabilities to improve planning and maintenance of the network. Queries such as how many sensors of a certain model are installed or what pieces of equipment have active problem reports are just a few examples of the type of information that is available to SIS users.

  4. Dynamic characteristics of background seismic noise according to records of nuclear monitoring seismic stations in Kazakstan

    International Nuclear Information System (INIS)

    Belyashova, N.N.; Sinyova, Z.I.; Komarov, I.I.; Mikhailova, N.N.

    1998-01-01

    The seismic stations of Kazakstan, included into nuclear monitoring network (see fig.1) are equipped with broad hand seismometers; seismic data are recorded in digital format. All this allows to investigate spectral and time characteristics of seismic background noise in very large frequency diapason (more than 3-5 orders), for all three components of oscillation vector. The spectral density of background seismic noise for vertical and both horizontal components (fig.2) was calculated for all of the observation points. The regular features of structure of noise spectra, inherent for all of the studied observation points, as well as some features, specific for studied places were found. The curves of spectral noise density were compared with global noise model, determined by the data of Global Seismological Network (GSN)

  5. Detecting earthquakes over a seismic network using single-station similarity measures

    Science.gov (United States)

    Bergen, Karianne J.; Beroza, Gregory C.

    2018-06-01

    New blind waveform-similarity-based detection methods, such as Fingerprint and Similarity Thresholding (FAST), have shown promise for detecting weak signals in long-duration, continuous waveform data. While blind detectors are capable of identifying similar or repeating waveforms without templates, they can also be susceptible to false detections due to local correlated noise. In this work, we present a set of three new methods that allow us to extend single-station similarity-based detection over a seismic network; event-pair extraction, pairwise pseudo-association, and event resolution complete a post-processing pipeline that combines single-station similarity measures (e.g. FAST sparse similarity matrix) from each station in a network into a list of candidate events. The core technique, pairwise pseudo-association, leverages the pairwise structure of event detections in its network detection model, which allows it to identify events observed at multiple stations in the network without modeling the expected moveout. Though our approach is general, we apply it to extend FAST over a sparse seismic network. We demonstrate that our network-based extension of FAST is both sensitive and maintains a low false detection rate. As a test case, we apply our approach to 2 weeks of continuous waveform data from five stations during the foreshock sequence prior to the 2014 Mw 8.2 Iquique earthquake. Our method identifies nearly five times as many events as the local seismicity catalogue (including 95 per cent of the catalogue events), and less than 1 per cent of these candidate events are false detections.

  6. Influence of wind turbines on seismic stations in the upper rhine graben, SW Germany

    Science.gov (United States)

    Zieger, Toni; Ritter, Joachim R. R.

    2018-01-01

    By analysing long- and short-term seismological measurements at wind farms close to the town of Landau, SW Germany, we present new insights into ground motion signals from wind turbines (WTs) at local seismic stations. Because of their need to be located in similar regions with sparsely anthropogenic activities, wind turbines impact seismic stations and their recordings in a way that is not yet fully understood by researchers. To ensure the undisturbed recording tasks of a regional seismic array or a single station by a protected area around those endangered stations, it is very important to investigate the behavior of WTs as a seismic source. For that reason, we calculate averaged one-hour long spectra of the power spectral density (PSD) before and after the installation of a new wind farm within the investigated area. These PSD are ordered according to the rotation speed. We observe a clear increase of the PSD level after the WT installation in a frequency range of 0.5 to 10 Hz up to a distance of 5.5 km away from the WT. By analysing seismic borehole data, we also observe a decrease of the PSD of wind dependent signals with depth. The impact of wind-dependent signals is found to be much more pronounced for the shallower station (150 m depth) than for the deeper one (305 m depth). Using short-term profile measurements, we fit a power-law decay proportional to 1/ r b to the main WT-induced PSD peaks and differentiate between near-field and far-field effects of ground motions. For low frequencies in the range from 1 to 4 Hz, we determine a b value of 0.78 to 0.85 for the far field, which is consistent with surface waves. The b value increases (up to 1.59) with increasing frequencies (up to 5.5 Hz), which is obviously due to attenuating effects like scattering or anelasticity. These results give a better understanding of the seismic wavefield interactions between wind turbines (or wind farms) with nearby seismic stations, including borehole installations, in a

  7. Seismic stations with GSM telemetry for registration of quarry blasts

    Czech Academy of Sciences Publication Activity Database

    Brož, Milan; Číž, Radim; Málek, Jiří; Žanda, Libor

    2000-01-01

    Roč. 2000, 16 (118) (2000), s. 25-32 ISSN 1211-1910 Institutional research plan: CEZ:AV0Z3046908 Keywords : blasting * seismic station * GSM mobile modem Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  8. A method to establish seismic noise baselines for automated station assessment

    Science.gov (United States)

    McNamara, D.E.; Hutt, C.R.; Gee, L.S.; Benz, H.M.; Buland, R.P.

    2009-01-01

    We present a method for quantifying station noise baselines and characterizing the spectral shape of out-of-nominal noise sources. Our intent is to automate this method in order to ensure that only the highest-quality data are used in rapid earthquake products at NEIC. In addition, the station noise baselines provide a valuable tool to support the quality control of GSN and ANSS backbone data and metadata. The procedures addressed here are currently in development at the NEIC, and work is underway to understand how quickly changes from nominal can be observed and used within the NEIC processing framework. The spectral methods and software used to compute station baselines and described herein (PQLX) can be useful to both permanent and portable seismic stations operators. Applications include: general seismic station and data quality control (QC), evaluation of instrument responses, assessment of near real-time communication system performance, characterization of site cultural noise conditions, and evaluation of sensor vault design, as well as assessment of gross network capabilities (McNamara et al. 2005). Future PQLX development plans include incorporating station baselines for automated QC methods and automating station status report generation and notification based on user-defined QC parameters. The PQLX software is available through the USGS (http://earthquake. usgs.gov/research/software/pqlx.php) and IRIS (http://www.iris.edu/software/ pqlx/).

  9. Seismic Tomography of Siyazan - Shabran Oil and Gas Region Of Azerbaijan by Data of The Seismic Stations

    Science.gov (United States)

    Yetirmishli, Gurban; Guliyev, Ibrahim; Mammadov, Nazim; Kazimova, Sabina; Ismailova, Saida

    2016-04-01

    The main purpose of the research was to build a reliable 3D model of the structure of seismic velocities in the earth crust on the territory of Siyazan-Shabran region of Azerbaijan, using the data of seismic telemetry stations spanning Siyazan-Shabran region (Siyazan, Altiagaj, Pirgulu, Guba, Khinalig, Gusar), including 7 mobile telemetry seismic stations. Interest to the problem of research seismic tomography caused by applied environmental objectives, such as the assessment of geological risks, engineering evaluation (stability and safety of wells), the task of exploration and mining operations. In the study region are being actively developed oil fields, and therefore, there is a risk of technogenic earthquakes. It was performed the calculation of first arrival travel times of P and S waves and the corresponding ray paths. Calculate 1D velocity model which is the initial model as a set of horizontal layers (velocity may be constant or changed linearly with depth on each layer, gaps are possible only at the boundaries between the layers). Have been constructed and analyzed the horizontal sections of the three-dimensional velocity model at different depths of the investigated region. By the empirical method was proposed density model of the sedimentary rocks at depths of 0-8 km.

  10. The SISIFO project: Seismic Safety at High Schools

    Science.gov (United States)

    Peruzza, Laura; Barnaba, Carla; Bragato, Pier Luigi; Dusi, Alberto; Grimaz, Stefano; Malisan, Petra; Saraò, Angela; Mucciarelli, Marco

    2014-05-01

    For many years, the Italian scientific community has faced the problem of the reduction of earthquake risk using innovative educational techniques. Recent earthquakes in Italy and around the world have clearly demonstrated that seismic codes alone are not able to guarantee an effective mitigation of risk. After the tragic events of San Giuliano di Puglia (2002), where an earthquake killed 26 school children, special attention was paid in Italy to the seismic safety of schools, but mainly with respect to structural aspects. Little attention has been devoted to the possible and even significant damage to non-structural elements (collapse of ceilings, tipping of cabinets and shelving, obstruction of escape routes, etc..). Students and teachers trained on these aspects may lead to a very effective preventive vigilance. Since 2002, the project EDURISK (www.edurisk.it) proposed educational tools and training programs for schools, at primary and middle levels. More recently, a nationwide campaign aimed to adults (www.iononrischio.it) was launched with the extensive support of civil protection volounteers. There was a gap for high schools, and Project SISIFO was designed to fill this void and in particular for those schools with technical/scientific curricula. SISIFO (https://sites.google.com/site/ogssisifo/) is a multidisciplinary initiative, aimed at the diffusion of scientific culture for achieving seismic safety in schools, replicable and can be structured in training the next several years. The students, helped by their teachers and by experts from scientific institutions, followed a course on specialized training on earthquake safety. The trial began in North-East Italy, with a combination of hands-on activities for the measurement of earthquakes with low-cost instruments and lectures with experts in various disciplines, accompanied by specifically designed teaching materials, both on paper and digital format. We intend to raise teachers and students knowledge of the

  11. Seismic noise study for a new seismic station at King Fahd University of Petroleum and Minerals in Saudi Arabia

    Science.gov (United States)

    Kaka, S. I.

    2012-04-01

    We have carried out a seismic noise study in order to understand the noise level at three selected locations at King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia. The main purpose is to select a suitable site with low seismic noise and good signal-to-noise ratio for our new broadband seismic station. There are several factors involved in the selection of a site location for a new station. Most importantly, we need to strike a balance between a logistically convenient site versus a technically suitable site. As a starting point, we selected six potential sites due to accessibility and proximity to the seismic processing center laboratory in the Department of Earth Sciences (ESD) at KFUPM. We then eliminated two sites that are relatively close to possible low-frequency noise sources. We have considered many possible noise sources which include: vehicle traffic / heavy machinery, the direct path of air flowing from air conditioning vent, tall trees / power poles and metal doorways. One more site was eliminated because the site was located in the open where it experiences maximum wind speed which is considered a major source of noise. All three potential sites are situated within the Dammam Dome where both lower middle and upper Rus Formations are exposed. The upper Rus is mainly made up of fine grained chalky limestone and the lower Rus is made up of alternation of marls and thin dolomitic limestone. The area is not known for any major faults and considered very low seismicity and hence the identification of seismoteconic features is not required. Before conducting the noise study, we calibrated and tested the seismic recording system, which was recently acquired by the ESD at KFUPM. The system includes a seismic recorder and a sensor with a GPS device. We deployed the system in order to measure the low-frequency background noise. Knowing the low frequency noise will help in predicting the high-frequency noise. The recording systems were

  12. Seismic margin review of the Maine Yankee Atomic Power Station: Fragility analysis

    International Nuclear Information System (INIS)

    Ravindra, M.K.; Hardy, G.S.; Hashimoto, P.S.; Griffin, M.J.

    1987-03-01

    This Fragility Analysis is the third of three volumes for the Seismic Margin Review of the Maine Yankee Atomic Power Station. Volume 1 is the Summary Report of the first trial seismic margin review. Volume 2, Systems Analysis, documents the results of the systems screening for the review. The three volumes are part of the Seismic Margins Program initiated in 1984 by the Nuclear Regulatory Commission (NRC) to quantify seismic margins at nuclear power plants. The overall objectives of the trial review are to assess the seismic margins of a particular pressurized water reactor, and to test the adequacy of this review approach, quantification techniques, and guidelines for performing the review. Results from the trial review will be used to revise the seismic margin methodology and guidelines so that the NRC and industry can readily apply them to assess the inherent quantitative seismic capacity of nuclear power plants

  13. Seismic margin review of the Maine Yankee Atomic Power Station: Fragility analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ravindra, M. K.; Hardy, G. S.; Hashimoto, P. S.; Griffin, M. J.

    1987-03-01

    This Fragility Analysis is the third of three volumes for the Seismic Margin Review of the Maine Yankee Atomic Power Station. Volume 1 is the Summary Report of the first trial seismic margin review. Volume 2, Systems Analysis, documents the results of the systems screening for the review. The three volumes are part of the Seismic Margins Program initiated in 1984 by the Nuclear Regulatory Commission (NRC) to quantify seismic margins at nuclear power plants. The overall objectives of the trial review are to assess the seismic margins of a particular pressurized water reactor, and to test the adequacy of this review approach, quantification techniques, and guidelines for performing the review. Results from the trial review will be used to revise the seismic margin methodology and guidelines so that the NRC and industry can readily apply them to assess the inherent quantitative seismic capacity of nuclear power plants.

  14. Could the IMS Infrasound Stations Support a Global Network of Small Aperture Seismic Arrays?

    OpenAIRE

    Kværna, Tormod; Gibbons, Steven; Mykkeltveit, Svein

    2017-01-01

    The IMS infrasound arrays have up to 15 sites with apertures up to 3 km. They are distributed remarkably uniformly over the globe, providing excellent coverage of South America, Africa, and Antarctica. Therefore, many infrasound arrays are in regions thousands of kilometers from the closest seismic array. Existing 3-component seismic stations, co-located with infrasound arrays, show how typical seismic signals look at these locations. We estimate a theoretical array response assuming a seismo...

  15. Multi-Use seismic stations offer strong deterrent to clandestine nuclear weapons testing

    Science.gov (United States)

    Hennet, C. B.; Van der Vink, G. E.; Richards, P. G.; Adushkin, V. V.; Kopnichev, Y. F.; Geary, R.

    As the United States and other nations push for the signing of a Comprehensive Test Ban Treaty, representatives are meeting in Geneva this year to develop an International Seismic Monitoring System to verify compliance with the treaty's restrictions. In addition to the official monitoring system, regional networks developed for earthquake studies and basic research can provide a strong deterrent against clandestine testing. The recent release of information by the U.S. Department of Energy (DoE) on previously unannounced nuclear tests provides an opportunity to assess the ability of multi-use seismic networks to help monitor nuclear testing across the globe.Here we look at the extent to which the formerly unannounced tests were recorded and identified on the basis of publicly available seismographic data recorded by five seismic networks. The data were recorded by networks in southern Nevada and northern California at stations less than 1500 km from the Nevada Test Site (NTS), and two networks in the former Soviet Union at stations farther than 1500 km from the NTS.

  16. Romanian Educational Seismic Network Project

    Science.gov (United States)

    Tataru, Dragos; Ionescu, Constantin; Zaharia, Bogdan; Grecu, Bogdan; Tibu, Speranta; Popa, Mihaela; Borleanu, Felix; Toma, Dragos; Brisan, Nicoleta; Georgescu, Emil-Sever; Dobre, Daniela; Dragomir, Claudiu-Sorin

    2013-04-01

    Romania is one of the most active seismic countries in Europe, with more than 500 earthquakes occurring every year. The seismic hazard of Romania is relatively high and thus understanding the earthquake phenomena and their effects at the earth surface represents an important step toward the education of population in earthquake affected regions of the country and aims to raise the awareness about the earthquake risk and possible mitigation actions. In this direction, the first national educational project in the field of seismology has recently started in Romania: the ROmanian EDUcational SEISmic NETwork (ROEDUSEIS-NET) project. It involves four partners: the National Institute for Earth Physics as coordinator, the National Institute for Research and Development in Construction, Urban Planning and Sustainable Spatial Development " URBAN - INCERC" Bucharest, the Babeş-Bolyai University (Faculty of Environmental Sciences and Engineering) and the software firm "BETA Software". The project has many educational, scientific and social goals. The main educational objectives are: training students and teachers in the analysis and interpretation of seismological data, preparing of several comprehensive educational materials, designing and testing didactic activities using informatics and web-oriented tools. The scientific objective is to introduce into schools the use of advanced instruments and experimental methods that are usually restricted to research laboratories, with the main product being the creation of an earthquake waveform archive. Thus a large amount of such data will be used by students and teachers for educational purposes. For the social objectives, the project represents an effective instrument for informing and creating an awareness of the seismic risk, for experimentation into the efficacy of scientific communication, and for an increase in the direct involvement of schools and the general public. A network of nine seismic stations with SEP seismometers

  17. Information on the technical site visit to the primary seismic station in Nairobi

    International Nuclear Information System (INIS)

    Kianji, G.; Nyali, H.

    2002-01-01

    In 1963 the World Wide Standardized Seismograph Station (WWSSN) was installed at the University of Nairobi (UoN) Department of Geology by the United States Geological Survey (USGS). Due to increased background seismic noise as a result of expanding infrastructure, the station was moved to Kilimambogo in 1994 and subsequently upgraded to IRIS digital station by the USGS. On the formation of CTBTO this tunnel type station was upgraded to the CTBTO standards. The system components and utilities are described. Comparison of data transmission through radio link at the University of Nairobi and the central station is provided. A map showing the location of the recent Tanzania earthquake incorporating CTBTO data and that of the local station is included

  18. Development and Performance of the Alaska Transportable Array Posthole Broadband Seismic Station

    Science.gov (United States)

    Aderhold, K.; Enders, M.; Miner, J.; Bierma, R. M.; Bloomquist, D.; Theis, J.; Busby, R. W.

    2017-12-01

    The final stations of the Alaska Transportable Array (ATA) will be constructed in 2017, completing the full footprint of 280 new and existing broadband seismic stations stretching across 19 degrees of latitude from western Alaska to western Canada. Through significant effort in planning, site reconnaissance, permitting and the considerable and concerted effort of field crews, the IRIS Alaska TA team is on schedule to successfully complete the construction of 194 new stations and upgrades at 28 existing stations over four field seasons. The station design and installation method was developed over the course of several years, leveraging the experience of the L48 TA deployments and existing network operators in Alaska as well as incorporating newly engineered components and procedures. A purpose-built lightweight drill was designed and fabricated to facilitate the construction of shallow boreholes to incorporate newly available posthole seismometers. This allowed for the development of a streamlined system of procedures to manufacture uniform seismic stations with minimal crew and minimal time required at each station location. A new station can typically be constructed in a single day with a four-person field crew. The ATA utilizes a hammer-drilled, cased posthole emplacement method adapted to the remote and harsh working environment of Alaska. The same emplacement design is implemented in all ground conditions to preserve uniformity across the array and eliminate the need for specialized mechanical equipment. All components for station construction are ideally suited for transport via helicopter, and can be adapted to utilize more traditional methods of transportation when available. This emplacement design delivers high quality data when embedded in bedrock or permafrost, reaching the low noise levels of benchmark permanent global broadband stations especially at long periods over 70 seconds. The TA will operate the network of real-time stations through at least

  19. The RING and Seismic Network: Data Acquisition of Co-located Stations

    Science.gov (United States)

    Falco, L.; Avallone, A.; Cattaneo, M.; Cecere, G.; Cogliano, R.; D'Agostino, N.; D'Ambrosio, C.; D'Anastasio, E.; Selvaggi, G.

    2007-12-01

    The plate boundary between Africa and Eurasia represents an interesting geodynamical region characterized by a complex pattern of deformation. First-order scientific problems regarding the existence of rigid blocks within the plate boundary, the present-day activity of the Calabrian subduction zone and the modes of release of seismic deformation are still awaiting for a better understanding. To address these issues, the INGV (Istituto Nazionale Geofisica e Vulcanlogia) deployed a permanent, integrated and real-time monitoring GPS network (RING) all over Italy. RING is now constituted by about 120 stations. The CGPS sites, acquiring at 1Hz and 30s sampling rate, are integrated either with broad band or very broad band seismometers and accelerometers for an improved definition of the seismically active regions. Most of the sites are connected to the acquisition centre (located in Rome and duplicated in Grottaminarda) through a satellite system (VSAT), while the remaining sites transmit data by Internet and classical phone connections. The satellite data transmission and the integration with seismic instruments makes this network one of the most innovative CGPS networks in Europe. The heterogeneity of the installed instrumentation, the transmission types and the increasing number of stations needed a central monitoring and acquisition system. A central acquisition system has been developed in Grottaminarda in southern Italy. Regarding the seismic monitoring we chose to use the open source system Earthworm, developed by USGS, with which we store waveforms and implement automatic localization of the seismic events occurring in the area. As most of the GPS sites are acquired by means of Nanometrics satellite technology, we developed a specific software (GpsView), written in Java, to monitor the state of health of those CGPS. This software receives GPS data from NaqsServer (Nanometrics acquisition system) and outputs information about the sites (i.e. approx position

  20. Seasonal variation of seismic ambient noise level at King Sejong Station, Antarctica

    Science.gov (United States)

    Lee, W.; Sheen, D.; Seo, K.; Yun, S.

    2009-12-01

    The generation of the secondary- or double-frequency (DF) microseisms with dominant frequencies between 0.1 and 0.5 Hz has been explained by nonlinear second-order pressure perturbations on the ocean bottom due to the interference of two ocean waves of equal wavelengths traveling in opposite directions. Korea Polar Research Institute (KOPRI) has been operating a broadband seismic station (KSJ1) at King George Island (KGI), Antarctica, since 2001. Examining the ambient seismic noise level for the period from 2006 to 2008 at KSJ1, we found a significant seasonal variation in the frequency range 0.1-0.5 Hz. Correlation of the DF peaks with significant ocean wave height and peak wave period models indicates that the oceanic infragravity waves in the Drake Passage is a possible source to excite the DF microseisms at KGI. Location of King Sejong Station, Antarctica Seasonal variations of DF peak, significant wave height, and peak wave period

  1. Seismic Station Installation Orientation Errors at ANSS and IRIS/USGS Stations

    Science.gov (United States)

    Ringler, Adam T.; Hutt, Charles R.; Persfield, K.; Gee, Lind S.

    2013-01-01

    Many seismological studies depend on the published orientations of sensitive axes of seismic instruments relative to north (e.g., Li et al., 2011). For example, studies of the anisotropic structure of the Earth’s mantle through SKS‐splitting measurements (Long et al., 2009), constraints on core–mantle electromagnetic coupling from torsional normal‐mode measurements (Dumberry and Mound, 2008), and models of three‐dimensional (3D) velocity variations from surface waves (Ekström et al., 1997) rely on accurate sensor orientation. Unfortunately, numerous results indicate that this critical parameter is often subject to significant error (Laske, 1995; Laske and Masters, 1996; Yoshizawa et al., 1999; Schulte‐Pelkum et al., 2001; Larson and Ekström, 2002). For the Advanced National Seismic System (ANSS; ANSS Technical Integration Committee, 2002), the Global Seismographic Network (GSN; Butler et al., 2004), and many other networks, sensor orientation is typically determined by a field engineer during installation. Successful emplacement of a seismic instrument requires identifying true north, transferring a reference line, and measuring the orientation of the instrument relative to the reference line. Such an exercise is simple in theory, but there are many complications in practice. There are four commonly used methods for determining true north at the ANSS and GSN stations operated by the USGS Albuquerque Seismological Laboratory (ASL), including gyroscopic, astronomical, Global Positioning System (GPS), and magnetic field techniques. A particular method is selected based on site conditions (above ground, below ground, availability of astronomical observations, and so on) and in the case of gyroscopic methods, export restrictions. Once a north line has been determined, it must be translated to the sensor location. For installations in mines or deep vaults, this step can include tracking angles through the one or more turns in the access tunnel leading to

  2. Data processing of natural and induced events recorded at the seismic station Ostrava-Kr¨¢sn¨¦ Pole (OKC

    Directory of Open Access Journals (Sweden)

    Nov¨¢k Josef

    2001-09-01

    Full Text Available The operation of the seismic station Ostrava-Kr¨¢sn¨¦ Pole (OKC (¦Õ = 49.8352¡ãN; ¦Ë = 18.1422¡ãE which is situated at present in an experimental gallery nearby the Ostrava planetarium started in the year 1983 being equiped initially by analogue instrumentation. Modernization of instrumentation at the station was aimed at the installation of a new digital data acquisition system and the respective software packages for data interpretation and transmission.Data acquisition system VISTEC is based on PC which enables continuous recording of three- component short-period and medium-period systems with the sampling frequency of 20 Hz. The basic advantage of the OS Linux adopted allows remote access (telnet and the possibility of the recorded data transmission (ftp. Possible troubles in the seismic station operation can be quickly detected (even automatically and all recorded data are with minimum delay on disposal. The use of the remote access makes possible also to change the parameters of measuring set-up. The standard form of output data allows the application of standard software packages for visualisation and evaluation. There are on disposal following formates: GSE2/CM6, GSE2/INT and MiniSEED. The output data sets can be compressed by a special procedure. For interactive interpretation od digital seismic data, software package EVENT developed in the Geophysical Institute AS CR and package WAVE developed in the Institute of Geonics AS CR are used.Experimental operation of digital seismographs at the station OKC confirmed justification of its incorporation into the seismic stations of the Czech national seismological network (CNSN. Based on the preliminary analysis of digital data it proved that following groups of seismic events are recorded: earthquakes, induced seismic events from Polish copper and coal mines, induced seismic events from the Ostrava-Karvin¨¢ Coal Basin, quarry blasts and weak regional seismic events of the

  3. Seismic Calibration of Group 1 IMS Stations in Eastern Asia for Improved IDC Event Location

    National Research Council Canada - National Science Library

    Murphy, J. R; Rodi, W. L; Johnson, M; Sultanov, J. D; Bennett, T. J; Toksoz, M. N; Ovtchinnikov, V; Barker, B. W; Rosca, A. M; Shchukin, Y

    2006-01-01

    .... In order to establish a robust nuclear test monitoring capability, it is necessary to calibrate the IMS seismic stations used in monitoring, to account for systematic deviations from the nominal travel time curves...

  4. Characterization of site conditions for selected seismic stations in eastern part of Romania

    Science.gov (United States)

    Grecu, B.; Zaharia, B.; Diaconescu, M.; Bala, A.; Nastase, E.; Constantinescu, E.; Tataru, D.

    2018-02-01

    Strong motion data are essential for seismic hazard assessment. To correctly understand and use this kind of data is necessary to have a good knowledge of local site conditions. Romania has one of the largest strong motion networks in Europe with 134 real-time stations. In this work, we aim to do a comprehensive site characterization for eight of these stations located in the eastern part of Romania. We make use of a various seismological dataset and we perform ambient noise and earthquake-based investigations to estimate the background noise level, the resonance frequencies and amplification of each site. We also derive the Vs30 parameter from the surface shear-wave velocity profiles obtained through the inversion of the Rayleigh waves recorded in active seismic measurements. Our analyses indicate similar results for seven stations: high noise levels for frequencies larger than 1 Hz, well defined fundamental resonance at low frequencies (0.15-0.29 Hz), moderate amplification levels (up to 4 units) for frequencies between 0.15 and 5-7 Hz and same soil class (type C) according to the estimated Vs30 and Eurocode 8. In contrast, the eighth station for which the soil class is evaluated of type B exhibits a very good noise level for a wide range of frequencies (0.01-20 Hz), a broader fundamental resonance at high frequencies ( 8 Hz) and a flat amplification curve between 0.1 and 3-4 Hz.

  5. Building an educational seismic network in Romanian schools

    Science.gov (United States)

    Zaharia, Bogdan; Tataru, Dragos; Grecu, Bogdan; Ionescu, Constantin; Bican-Brisan, Nicoleta; Neagoe, Cristian

    2014-05-01

    Understanding the earthquake phenomena and their effects is an important step toward the education of population and aims to raise the awareness about the earthquake risk and possible mitigation actions. In this sense, The Romanian Educational Seismic Network project represents an efficient communication tool, allowing teaching and learning about the earthquakes and seismic wave impact through experimental practices and educational activities. The seismic network consist of nine SEP seismometers installed in high-schools from the most important seismic areas (Vrancea, Banat, Făgăraş, Dobrogea), vulnerable cities (Bucharest, Iasi) or high populated places (Cluj, Sibiu, Timisoara, Zalău) and is coordinated by the National Institute of Earth Physics from Bucharest. Once installed, the seismic network is the starting point of activities for students through an e-learning platform. Some objectives are aimed: - To train students and teachers how to make analysis and interpretation of seismological data; - To make science more interesting for students; - To improve the participation rates in physical sciences for students; - To raise awareness of geoscience as a scientific discipline for pre-university students; - To promote the installation and effective use of educational seismographs and seismic data; - To reinforce and develop relationships between participating schools and research institutes; - To create an earthquake database this will be used by students and teachers for educational purposes. Different types of practical activities using educational seismometer, designed by researchers for students, are described in educational materials and in the web platform project. Also we encourage the teachers from the participating schools to share their experiences and produce new didactic tools for the classroom. This collaborative work could illustrate the conjugated efforts of researchers and teachers for a better education and awareness of the risk culture

  6. Validation of seismic soil structure interaction (SSI) methodology for a UK PWR nuclear power station

    International Nuclear Information System (INIS)

    Llambias, J.M.

    1993-01-01

    The seismic loading information for use in the seismic design of equipment and minor structures within a nuclear power plant is determined from a dynamic response analysis of the building in which they are located. This dynamic response analysis needs to capture the global response of both the building structure and adjacent soil and is commonly referred to as a soil structure interaction (SSI) analysis. NNC have developed a simple and cost effective methodology for the seismic SSI analysis of buildings in a PWR nuclear power station at a UK soft site. This paper outlines the NNC methodology and describes the approach adopted for its validation

  7. New seismic monitoring observation system and data accessibility at Syowa Station

    Directory of Open Access Journals (Sweden)

    Masaki Kanao

    1999-03-01

    Full Text Available The seismic observation system at Syowa Station, East Antarctica was fully replaced in the wintering season of the 38th Japanese Antarctic Research Expedition (JARE-38 in 1996-1998. The old seismographic vault constructed in 1970 was closed at the end of JARE-38 because of cumulative damage to the inner side of the vault by continuous flowing in of water from walls in summer and its freezing in winter. All the seismometers were moved to a new seismographic hut (69°00′24.0″S, 39°35′06.0″E and 20m above mean sea level in April 1997. Seismic signals of the short-period (HES and broadband (STS-1 seismometers in the new hut are transmitted to the Earth Science Laboratory (ESL via analog cable 600m in length. The new acquisition system was installed in the ESL with 6-channel 24-bit A/D converters for both sensor signals. All digitized data are automatically transmitted from the A/D converter to a workstation via TCP/IP protocol. After parallel observations with the old acquisition system by personal computers and the new system during the wintering season of JARE-38,the main system was changed to the new one, which has some advantages for both the reduction of daily maintenance efforts and the data transport/communication processes via Internet by use of LAN at the station. In this report, details of the new seismographic hut and the recording system are described. Additionally, the seismic data accessibility for public use, including Internet service, is described.

  8. Lessons learned from the seismic reevaluation of San Onofre Nuclear Generating Station, Unit 1

    International Nuclear Information System (INIS)

    Russell, M.J.; Shieh, L.C.; Tsai, N.C.; Cheng, T.M.

    1987-01-01

    A seismic reevaluation program was conducted for the San Onofre Nuclear Generating Station, Unit No. 1 (SONGS 1). SEP was created by the NRC to provide (1) an assessment of the significance of differences between current technical positions on safety issues and those that existed when a particular plant was licensed, (2) a basis for deciding on how these differences should be resolved in an integrated plant review, and (3) a documented evaluation of plant safety. The Systematic Evaluation Program (SEP) seismic review for SONGS 1 was exacerbated by the results of an evaluation of an existing capable fault near the site during the design review for Units 2 and 3, which resulted in a design ground acceleration of 0.67g. Southern California Edison Company (SCE), the licensee for SONGS 1, realized that a uniform application of existing seismic criteria and methods would not be feasible for the upgrading of SONGS 1 to such a high seismic requirement. Instead, SCE elected to supplement existing seismic criteria and analysis methods by developing criteria and methods closer to the state of the art in seismic evaluation techniques

  9. Seismic Noise Analysis and Reduction through Utilization of Collocated Seismic and Atmospheric Sensors at the GRO Chile Seismic Network

    Science.gov (United States)

    Farrell, M. E.; Russo, R. M.

    2013-12-01

    The installation of Earthscope Transportable Array-style geophysical observatories in Chile expands open data seismic recording capabilities in the southern hemisphere by nearly 30%, and has nearly tripled the number of seismic stations providing freely-available data in southern South America. Through the use of collocated seismic and atmospheric sensors at these stations we are able to analyze how local atmospheric conditions generate seismic noise, which can degrade data in seismic frequency bands at stations in the ';roaring forties' (S latitudes). Seismic vaults that are climate-controlled and insulated from the local environment are now employed throughout the world in an attempt to isolate seismometers from as many noise sources as possible. However, this is an expensive solution that is neither practical nor possible for all seismic deployments; and also, the increasing number and scope of temporary seismic deployments has resulted in the collection and archiving of terabytes of seismic data that is affected to some degree by natural seismic noise sources such as wind and atmospheric pressure changes. Changing air pressure can result in a depression and subsequent rebound of Earth's surface - which generates low frequency noise in seismic frequency bands - and even moderate winds can apply enough force to ground-coupled structures or to the surface above the seismometers themselves, resulting in significant noise. The 10 stations of the permanent Geophysical Reporting Observatories (GRO Chile), jointly installed during 2011-12 by IRIS and the Chilean Servicio Sismológico, include instrumentation in addition to the standard three seismic components. These stations, spaced approximately 300 km apart along the length of the country, continuously record a variety of atmospheric data including infrasound, air pressure, wind speed, and wind direction. The collocated seismic and atmospheric sensors at each station allow us to analyze both datasets together, to

  10. Tools for educational access to seismic data

    Science.gov (United States)

    Taber, J. J.; Welti, R.; Bravo, T. K.; Hubenthal, M.; Frechette, K.

    2017-12-01

    Student engagement can be increased both by providing easy access to real data, and by addressing newsworthy events such as recent large earthquakes. IRIS EPO has a suite of access and visualization tools that can be used for such engagement, including a set of three tools that allow students to explore global seismicity, use seismic data to determine Earth structure, and view and analyze near-real-time ground motion data in the classroom. These tools are linked to online lessons that are designed for use in middle school through introductory undergraduate classes. The IRIS Earthquake Browser allows discovery of key aspects of plate tectonics, earthquake locations (in pseudo 3D) and seismicity rates and patterns. IEB quickly displays up to 20,000 seismic events over up to 30 years, making it one of the most responsive, practical ways to visualize historical seismicity in a browser. Maps are bookmarkable and preserve state, meaning IEB map links can be shared or worked into a lesson plan. The Global Seismogram Plotter automatically creates visually clear seismic record sections from selected large earthquakes that are tablet-friendly and can also to be printed for use in a classroom without computers. The plots are designed to be appropriate for use with no parameters to set, but users can also modify the plots, such as including a recording station near a chosen location. A guided exercise is provided where students use the record section to discover the diameter of Earth's outer core. Students can pick and compare phase arrival times onscreen which is key to performing the exercise. A companion station map shows station locations and further information and is linked to the record section. jAmaSeis displays seismic data in real-time from either a local instrument and/or from remote seismic stations that stream data using standard seismic data protocols, and can be used in the classroom or as a public display. Users can filter data, fit a seismogram to travel time

  11. Scientific goals of SCHOOLS & QUAKES

    Science.gov (United States)

    Brückl, Ewald; Köberl, Christian; Lenhardt, Wolfgang; Mertl, Stefan; Rafeiner-Magor, Walter; Stark, Angelika; Stickler, Gerald; Weber, Robert

    2015-04-01

    In many countries around the world seismometers are used in schools to broaden the knowledge in seismology in a vivid way and to take part in the observation of the current worldwide seismic activity. SCHOOLS & QUAKES is a project within the Sparkling Science program (http://www.sparklingscience.at), which not only pursues the given educational goals but also integrates scholars in seismological research permitting their own contributions. Research within SCHOOLS & QUAKES concentrates on the seismic activity of the Mürz Valley - Semmering - Vienna Basin transfer fault system in Austria because of its relatively high earthquake hazard and risk. The detection of low magnitude local earthquakes (magnitude ≤ 2), precise location of hypocenters, determination of the focal mechanisms, and correlation of hypocenters with active geological structures are the main scientific goals in this project. Furthermore, the long term build-up of tectonic stress, slip deficit and aseismic slip, and the maximum credible earthquake in this area are issues to be addressed. The scientific efforts of SCHOOLS & QUAKES build on the work of the Seismological Service of Austria at the Zentralanstalt für Meteorologie und Geodynamik (ZAMG), and benefit from the findings on the lithospheric structure of the Eastern Alps gained by the CELEBRATION 2000 and ALP 2002 projects. Regional Vp and Vs-models were derived from this data covering the SCHOOLS & QUAKES target area. Within the ALPAACT project (Seismological and geodetic monitoring of ALpine-PAnnonian ACtive Tectonics) the seismic network of the target area was densified by 7 broadband und 2 short period stations. Relocations based on a 3D-velocity model and the densified seismic network yielded substantially higher spatial resolution of seismically active structures. A new method based on waveform stacking (GRA, 16, EGU2014-5722) allowed for focal mechanism solutions of low magnitude (Ml ~2.5) events. Data from 22 GNSS stations have been

  12. OBS Technologies and permanent seismic Stations at Sea

    Science.gov (United States)

    Makris, J.; Nikolova, S. B.

    2003-04-01

    An off-shore telemetric system was developed during last 2 years. It consists of a buoy unit, OBS with seismic sensor and digitizer at the sea floor and coaxial cable for transferring data from the sea. The buoy unit includes all components for recording and transmitting data to the base station. A solar panel and wind generator are the sources of energy that charge the batteries in the buoy. An Omni directional antenna and a radio modem are used for data transfer. The buoy can be connected also to mobile network or satellite. The Seismic recording unit is SEDIS IV developed in GeoPro GmbH which is a 6 channel data logger equipped with a hard disk of 30 GByte capacity and a flash memory of 0.5 Gbyte which can continuously record at different sampling rate (from 31.25 to 1000sps). The operating system for SEDIS IV is LINUX, with possible data compression, event location and extraction. The data transfer and supply of the power to seismometer and ADC unit in OBS sphere is done through coaxial cable, connecting the buoy unit and OBS. The whole system was tested for a period of one month (October 2002) within frame of Nestor program in Pilos (Greece) and worked successfully.

  13. Analysis of the ULF electromagnetic emission related to seismic activity, Teoloyucan geomagnetic station, 1998-2001

    Directory of Open Access Journals (Sweden)

    A. Kotsarenko

    2004-01-01

    Full Text Available Results of ULF geomagnetic measurements at station Teoloyucan (Central Mexico, 99.11'35.735''W, 19.44'45.100''N, 2280m height in relation to seismic activity in the period 1998-2001 and their analysis are presented. Variations of spectral densities for horizontal and vertical components, polarization densities and spectrograms of magnetic field, their derivatives are analyzed as a part of traditional analysis in this study. Values of spectral density were calculated for 6 fixed frequencies f=1, 3, 10, 30, 100 and 300mHz. Fractal characteristics of spectra were analyzed in the conception of SOC (Self-Organized Criticality. 2 nighttime intervals, 0-3 and 3-6h by local time have been used to decrease the noise interference in row data. In order to exclude the intervals with a high geomagnetic activity from analysis we referred to Ap indices, calculated for corresponding time intervals. The contribution of seismic events to geomagnetic emission was estimated by seismic index ks=100.75Ms/10D, where Ms is the amplitude of the earthquake and D is the distance from its epicenter to the station.

  14. Complex researches on substantiation of construction and seismic stability of large dams in seismic region

    International Nuclear Information System (INIS)

    Negmatullaev, S.Kh.; Yasunov, P.A.

    2001-01-01

    This article is devoted to complex researches on substantiation of construction and seismic stability of large dams (Nurec hydroelectric power station) in seismic region. Geological, seismological, model, and engineering investigations are discussed in this work. At construction of Nurec hydroelectric power station the rich experience is accumulated. This experience can be used in analogous seismically active regions at construction similar hydroelectric power stations.

  15. Existing School Buildings: Incremental Seismic Retrofit Opportunities.

    Science.gov (United States)

    Federal Emergency Management Agency, Washington, DC.

    The intent of this document is to provide technical guidance to school district facility managers for linking specific incremental seismic retrofit opportunities to specific maintenance and capital improvement projects. The linkages are based on logical affinities, such as technical fit, location of the work within the building, cost saving…

  16. Sources of high frequency seismic noise: insights from a dense network of ~250 stations in northern Alsace (France)

    Science.gov (United States)

    Vergne, Jerome; Blachet, Antoine; Lehujeur, Maximilien

    2015-04-01

    Monitoring local or regional seismic activity requires stations having a low level of background seismic noise at frequencies higher than few tenths of Hertz. Network operators are well aware that the seismic quality of a site depends on several aspects, among them its geological setting and the proximity of roads, railways, industries or trees. Often, the impact of each noise source is only qualitatively known which precludes estimating the quality of potential future sites before they are tested or installed. Here, we want to take advantage of a very dense temporary network deployed in Northern Alsace (France) to assess the effect of various kinds of potential sources on the level of seismic noise observed in the frequency range 0.2-50 Hz. In September 2014, more than 250 seismic stations (FairfieldNodal@ Zland nodes with 10Hz vertical geophone) have been installed every 1.5 km over a ~25km diameter disc centred on the deep geothermal sites of Soultz-sous-Forêts and Rittershoffen. This region exhibits variable degrees of human imprints from quite remote areas to sectors with high traffic roads and big villages. It also encompasses both the deep sedimentary basin of the Rhine graben and the piedmont of the Vosges massif with exposed bedrock. For each site we processed the continuous data to estimate probability density functions of the power spectral densities. At frequencies higher than 1 Hz most sites show a clear temporal modulation of seismic noise related to human activity with the well-known variations between day and night and between weekdays and weekends. Moreover we observe a clear evolution of the spatial distribution of seismic noise levels with frequency. Basically, between 0.5 and 4 Hz the geological setting modulates the level of seismic noise. At higher frequencies, the amplitude of seismic noise appears mostly related to the distance to nearby roads. Based on road maps and traffic estimation, a forward approach is performed to model the induced

  17. Preliminary consideration on the seismic actions recorded during the 2016 Central Italy seismic sequence

    Science.gov (United States)

    Carlo Ponzo, Felice; Ditommaso, Rocco; Nigro, Antonella; Nigro, Domenico S.; Iacovino, Chiara

    2017-04-01

    After the Mw 6.0 mainshock of August 24, 2016 at 03.36 a.m. (local time), with the epicenter located between the towns of Accumoli (province of Rieti), Amatrice (province of Rieti) and Arquata del Tronto (province of Ascoli Piceno), several activities were started in order to perform some preliminary evaluations on the characteristics of the recent seismic sequence in the areas affected by the earthquake. Ambient vibration acquisitions have been performed using two three-directional velocimetric synchronized stations, with a natural frequency equal to 0.5Hz and a digitizer resolution of equal to 24bit. The activities are continuing after the events of the seismic sequence of October 26 and October 30, 2016. In this paper, in order to compare recorded and code provision values in terms of peak (PGA, PGV and PGD), spectral and integral (Housner Intensity) seismic parameters, several preliminary analyses have been performed on accelerometric time-histories acquired by three near fault station of the RAN (Italian Accelerometric Network): Amatrice station (station code AMT), Norcia station (station code NRC) and Castelsantangelo sul Nera station (station code CNE). Several comparisons between the elastic response spectra derived from accelerometric recordings and the elastic demand spectra provided by the Italian seismic code (NTC 2008) have been performed. Preliminary results retrieved from these analyses highlight several apparent difference between experimental data and conventional code provision. Then, the ongoing seismic sequence appears compatible with the historical seismicity in terms of integral parameters, but not in terms of peak and spectral values. It seems appropriate to reconsider the necessity to revise the simplified design approach based on the conventional spectral values. Acknowledgements This study was partially funded by the Italian Department of Civil Protection within the project DPC-RELUIS 2016 - RS4 ''Seismic observatory of structures and

  18. A Demonstration Training Program for Potential School Dropouts. A Service Station Training School for Dropout-Prone Students.

    Science.gov (United States)

    Rull, Marvin H.; Moore, Richard O.

    One phase of the curriculum demonstration program sponsored jointly by the Quincy Public Schools and Southern Illinois University is the Service Station Training School described within this report. The Service Station Training School was one of several sheltered work stations which were developed to provide preemployment experiences and training…

  19. Methods for the seismic effect analysis on the nuclear power station structures

    International Nuclear Information System (INIS)

    Jeanpierre, F.; Livolant, M.

    1980-01-01

    Seismic activity in France is far from being as great as in other parts of the globe, for instance Japan, California and Peru, in particular, and very few people are shocked at the idea of having to suffer from an earthquake, although periodically, such as at Arette, Oleron, etc., events do occur to remind one that seismic tremors of significant intensity can happen. In the case of nuclear reactors and given the serious secondary effects that uncontrolled destructions could involve, particularly the bursting of containment vessels or the non operation of safety systems such as the automatic drop of rods to halt the chain reaction, the earthquake hazard must be taken into account, in terms of the location of the power station, and the effects of the seism carefully estimated. The purpose of this report is briefly to describe the methods used to this end [fr

  20. Application of continuous seismic-reflection techniques to delineate paleochannels beneath the Neuse River at US Marine Corps Air Station, Cherry Point, North Carolina

    Science.gov (United States)

    Cardinell, Alex P.

    1999-01-01

    A continuous seismic-reflection profiling survey was conducted by the U.S. Geological Survey on the Neuse River near the Cherry Point Marine Corps Air Station during July 7-24, 1998. Approximately 52 miles of profiling data were collected during the survey from areas northwest of the Air Station to Flanner Beach and southeast to Cherry Point. Positioning of the seismic lines was done by using an integrated navigational system. Data from the survey were used to define and delineate paleochannel alignments under the Neuse River near the Air Station. These data also were correlated with existing surface and borehole geophysical data, including vertical seismic-profiling velocity data collected in 1995. Sediments believed to be Quaternary in age were identified at varying depths on the seismic sections as undifferentiated reflectors and lack the lateral continuity of underlying reflectors believed to represent older sediments of Tertiary age. The sediments of possible Quaternary age thicken to the southeast. Paleochannels of Quaternary age and varying depths were identified beneath the Neuse River estuary. These paleochannels range in width from 870 feet to about 6,900 feet. Two zones of buried paleochannels were identified in the continuous seismic-reflection profiling data. The eastern paleochannel zone includes two large superimposed channel features identified during this study and in re-interpreted 1995 land seismic-reflection data. The second paleochannel zone, located west of the first paleochannel zone, contains several small paleochannels near the central and south shore of the Neuse River estuary between Slocum Creek and Flanner Beach. This second zone of channel features may be continuous with those mapped by the U.S. Geological Survey in 1995 using land seismic-reflection data on the southern end of the Air Station. Most of the channels were mapped at the Quaternary-Tertiary sediment boundary. These channels appear to have been cut into the older sediments

  1. Cultural noise and the night-day asymmetry of the seismic activity recorded at the Bunker-East (BKE) Vesuvian Station

    Science.gov (United States)

    Scafetta, Nicola; Mazzarella, Adriano

    2018-01-01

    Mazzarella and Scafetta (2016) showed that the seismic activity recorded at the Bunker-East (BKE) Vesuvian station from 1999 to 2014 suggests a higher nocturnal seismic activity. However, this station is located at about 50 m from the main road to the volcano's crater and since 2009 its seismograms also record a significant diurnal cultural noise due mostly to tourist tours to Mt. Vesuvius. Herein, we investigate whether the different seismic frequency between day and night times could be an artifact of the peculiar cultural noise that affects this station mostly from 9:00 am to 5:00 pm from spring to fall. This time-distributed cultural noise should evidently reduce the possibility to detect low magnitude earthquakes during those hours but not high magnitude events. Using hourly distributions referring to different magnitude thresholds from M = 0.2 to M = 2.0, the Gutenberg-Richter magnitude-frequency diagram applied to the day and night-time sub-catalogs and Montecarlo statistical modeling, we demonstrate that the day-night asymmetry persists despite an evident disruption induced by cultural noise during day-hours. In particular, for the period 1999-2017, and for earthquakes with M ≥ 2 we found a Gutenberg-Richter exponent b = 1.66 ± 0.07 for the night-time events and b = 2.06 ± 0.07 for day-time events. Moreover, we repeat the analysis also for an older BKE catalog covering the period from 1992 to 2000 when cultural noise was not present. The analysis confirms a higher seismic nocturnal activity that is also characterized by a smaller Gutenberg-Richter exponent b for M ≥ 2 earthquakes relative to the day-time activity. Thus, the found night-day seismic asymmetric behavior is likely due to a real physical feature affecting Mt. Vesuvius.

  2. Seismic structural fragility investigation for the San Onofre Nuclear Generating Station, Unit 1 (Project I); SONGS-1 AFWS Project

    International Nuclear Information System (INIS)

    Wesley, D.A.; Hashimoto, P.S.

    1982-04-01

    An evaluation of the seismic capacities of several of the San Onofre Nuclear Generating Station, Unit 1 (SONGS-1) structures was conducted to determine input to the overall probabilistic methodology developed by Lawrence Livermore National Laboratory. Seismic structural fragilities to be used as input consist of median seismic capacities and their variabilities due to randomness and uncertainty. Potential failure modes were identified for each of the SONGS-1 structures included in this study by establishing the seismic load-paths and comparing expected load distributions to available capacities for the elements of each load-path. Particular attention was given to possible weak links and details. The more likely failure modes were screened for more detailed investigation

  3. Site response assessment using borehole seismic records

    Energy Technology Data Exchange (ETDEWEB)

    Park, Donghee; Chang, Chunjoong; Choi, Weonhack [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    In regions with high seismic activity, such as Japan, the Western United States and Taiwan, borehole seismometers installed deep underground are used to monitor seismic activity during the course of seismic wave propagation at various depths and to study the stress changes due to earthquakes and analyze the connection to fault movements. The Korea Meteorological Administration (KMA) and the Korea Institute of Geology and Mining (KIGAM) have installed and are operating borehole seismometers at a depth of 70∼100 meters for the precise determination of epicenters. Also, Korea Hydro and Nuclear Power Co., Ltd. (KHNP) has installed and is operating 2 borehole seismic stations near Weolseong area to observe at a depth of 140 meters seismic activities connected to fault activity. KHNP plans to operate in the second half of 2014 a borehole seismic station for depths less than 300 and 600 meters in order to study the seismic response characteristics in deep strata. As a basic study for analyzing ground motion response characteristics at depths of about 300 to 600 meters in connection with the deep geological disposal of spent nuclear fuel, the present study examined the background noise response characteristics of the borehole seismic station operated by KHNP. In order to analyze the depth-dependent impact of seismic waves at deeper depths than in Korea, seismic data collected by Japan's KIK-net seismic stations were used and the seismic wave characteristics analyzed by size and depth. In order to analyze the borehole seismic observation data from the seismic station operated by KHNP, this study analyzed the background noise characteristics by using a probability density function.

  4. Site response assessment using borehole seismic records

    International Nuclear Information System (INIS)

    Park, Donghee; Chang, Chunjoong; Choi, Weonhack

    2014-01-01

    In regions with high seismic activity, such as Japan, the Western United States and Taiwan, borehole seismometers installed deep underground are used to monitor seismic activity during the course of seismic wave propagation at various depths and to study the stress changes due to earthquakes and analyze the connection to fault movements. The Korea Meteorological Administration (KMA) and the Korea Institute of Geology and Mining (KIGAM) have installed and are operating borehole seismometers at a depth of 70∼100 meters for the precise determination of epicenters. Also, Korea Hydro and Nuclear Power Co., Ltd. (KHNP) has installed and is operating 2 borehole seismic stations near Weolseong area to observe at a depth of 140 meters seismic activities connected to fault activity. KHNP plans to operate in the second half of 2014 a borehole seismic station for depths less than 300 and 600 meters in order to study the seismic response characteristics in deep strata. As a basic study for analyzing ground motion response characteristics at depths of about 300 to 600 meters in connection with the deep geological disposal of spent nuclear fuel, the present study examined the background noise response characteristics of the borehole seismic station operated by KHNP. In order to analyze the depth-dependent impact of seismic waves at deeper depths than in Korea, seismic data collected by Japan's KIK-net seismic stations were used and the seismic wave characteristics analyzed by size and depth. In order to analyze the borehole seismic observation data from the seismic station operated by KHNP, this study analyzed the background noise characteristics by using a probability density function

  5. Operations plan for the Regional Seismic Test Network

    International Nuclear Information System (INIS)

    1981-01-01

    The Regional Seismic Test Network program was established to provide a capability for detection of extremely sensitive earth movements. Seismic signals from both natural and man-made earth motions will be analyzed with the ultimate objective of accurately locating underground nuclear explosions. The Sandia National Laboratories, Albuquerque, has designed an unattended seismic station capable of recording seismic information received at the location of the seismometers installed as part of that specific station. A network of stations is required to increase the capability of determining the source of the seismic signal and the location of the source. Current plans are to establish a five-station seismic network in the United States and Canada. The Department of Energy, Nevada Operations Office, has been assigned the responsibility for deploying, installing, and operating these remote stations. This Operation Plan provides the basic information and tasking to accomplish this assignment

  6. Passive seismic experiment - A summary of current status. [Apollo-initiated lunar surface station data

    Science.gov (United States)

    Latham, G. V.; Dorman, H. J.; Horvath, P.; Ibrahim, A. K.; Koyama, J.; Nakamura, Y.

    1978-01-01

    The data set obtained from the four-station Apollo seismic network including signals from approximately 11,800 events, is surveyed. Some refinement of the lunar model will result, but its gross features remain the same. Attention is given to the question of a small, molten lunar core, the answer to which remains dependent on analysis of signals from a far side impact. Seventy three sources of repeating, deep moonquakes have been identified, thirty nine of which have been accurately located. Concentrated at depths from 800 to 1000 km, the periodicities of these events have led to the hypothesis that they are generated by tidal stresses. Lunar seismic data has also indicated that the meteoroid population is ten times lower than originally determined from earth based observations. Lunar seismic activity is much lower and mountainous masses show no sign of sinking, in contrast to earth, as a result of the lunar crust being four times thicker. While much work remains to be done, significant correlation between terrestrial and lunar observations can be seen.

  7. Receiver function structure beneath a broad-band seismic station in south Sumatra

    Science.gov (United States)

    MacPherson, K. A.; Hidayat, D.; Goh, S.

    2010-12-01

    We estimated the one-dimensional velocity structure beneath a broad-band station in south Sumatra by the forward modeling and inversion of receiver functions. Station PMBI belongs to the GEOFON seismic network maintained by GFZ-Potsdam, and at a longitude of 104.77° and latitude of -2.93°, sits atop the south Sumatran basin. This station is of interest to researchers at the Earth Observatory of Singapore, as data from it and other stations in Sumatra and Singapore will be incorporated into a regional velocity model for use in seismic hazard analyses. Three-component records from 193 events at teleseismic distances and Mw ≥ 5.0 were examined for this study and 67 records were deemed to have sufficient signal to noise characteristics to be retained for analysis. Observations are primarily from source zones in the Bougainville trench with back-azimuths to the east-south-east, the Japan and Kurile trenches with back-azimuths to the northeast, and a scattering of observations from other azimuths. Due to the level of noise present in even the higher-quality records, the usual frequency-domain deconvolution method of computing receiver functions was ineffective, and a time-domain iterative deconvolution was employed to obtain usable wave forms. Receiver functions with similar back-azimuths were stacked in order to improve their signal to noise ratios. The resulting wave forms are relatively complex, with significant energy being present in the tangential components, indicating heterogeneity in the underlying structure. A dip analysis was undertaken but no clear pattern was observed. However, it is apparent that polarities of the tangential components were generally reversed for records that sample the Sunda trench. Forward modeling of the receiver functions indicates the presence of a near-surface low-velocity layer (Vp≈1.9 km/s) and a Moho depth of ~31 km. Details of the crustal structure were investigated by employing time-domain inversions of the receiver

  8. The Banat seismic network: Evolution and performance

    International Nuclear Information System (INIS)

    Oros, E.

    2002-01-01

    In the Banat Seismic Region, with its important seismogenic zones (Banat and Danube), operates today the Banat Seismic Network. This network has four short period seismic stations telemetered at the Timisoara Seismological Observatory (since 1995): Siria, Banloc, Buzias and Timisoara. The stations are equipped with short-period S13 seismometers (1 second). The data recorded by the short-period stations are telemetered to Timisoara where they are digitized at 50 samples per second, with 16 bit resolution. At Timisoara works SAPS, an automated system for data acquisition and processing, which performs real-time event detection (based on Allen algorithm), discrimination between local and teleseismic events, automatic P and S waves picking, location and magnitude determination for local events and teleseisms, 'feeding' of an Automatic Data Request Manager with phases, locations and waveforms, sending of earthquake information (as phases and location), by e-mail to Bucharest. The beginning of the seismological observations in Banat is in the 1880's (Timisoara Meteorological Observatory). The first seismograph was installed in Timisoara in 1901, and its systematic observations began in 1902. The World War I interrupted its work. In 1942 Prof. I. Curea founded the Seismic Station Timisoara, and since 1967 until today this station worked into a special building. After 1972 two stations with high amplification were installed in Retezat Mts (Gura Zlata) and on Nera Valey (Susara), as a consequence of the research results. Since 1982 Buzias station began to work completing the Banat Seismic Network. Therefore, the network could detect and locate any local seismic event with M > 2.2. Moreover, up to 20 km distance from each station any seismic event could be detected over M = 0.5. The paper also presents the quality of the locations versus different local seismic sources. (author)

  9. Antarctic ice sheet thickness estimation using the horizontal-to-vertical spectral ratio method with single-station seismic ambient noise

    Directory of Open Access Journals (Sweden)

    P. Yan

    2018-03-01

    Full Text Available We report on a successful application of the horizontal-to-vertical spectral ratio (H / V method, generally used to investigate the subsurface velocity structures of the shallow crust, to estimate the Antarctic ice sheet thickness for the first time. Using three-component, five-day long, seismic ambient noise records gathered from more than 60 temporary seismic stations located on the Antarctic ice sheet, the ice thickness measured at each station has comparable accuracy to the Bedmap2 database. Preliminary analysis revealed that 60 out of 65 seismic stations on the ice sheet obtained clear peak frequencies (f0 related to the ice sheet thickness in the H / V spectrum. Thus, assuming that the isotropic ice layer lies atop a high velocity half-space bedrock, the ice sheet thickness can be calculated by a simple approximation formula. About half of the calculated ice sheet thicknesses were consistent with the Bedmap2 ice thickness values. To further improve the reliability of ice thickness measurements, two-type models were built to fit the observed H / V spectrum through non-linear inversion. The two-type models represent the isotropic structures of single- and two-layer ice sheets, and the latter depicts the non-uniform, layered characteristics of the ice sheet widely distributed in Antarctica. The inversion results suggest that the ice thicknesses derived from the two-layer ice models were in good concurrence with the Bedmap2 ice thickness database, and that ice thickness differences between the two were within 300 m at almost all stations. Our results support previous finding that the Antarctic ice sheet is stratified. Extensive data processing indicates that the time length of seismic ambient noise records can be shortened to two hours for reliable ice sheet thickness estimation using the H / V method. This study extends the application fields of the H / V method and provides an effective and independent way to measure

  10. Detection capability of the IMS seismic network based on ambient seismic noise measurements

    Science.gov (United States)

    Gaebler, Peter J.; Ceranna, Lars

    2016-04-01

    All nuclear explosions - on the Earth's surface, underground, underwater or in the atmosphere - are banned by the Comprehensive Nuclear-Test-Ban Treaty (CTBT). As part of this treaty, a verification regime was put into place to detect, locate and characterize nuclear explosion testings at any time, by anyone and everywhere on the Earth. The International Monitoring System (IMS) plays a key role in the verification regime of the CTBT. Out of the different monitoring techniques used in the IMS, the seismic waveform approach is the most effective technology for monitoring nuclear underground testing and to identify and characterize potential nuclear events. This study introduces a method of seismic threshold monitoring to assess an upper magnitude limit of a potential seismic event in a certain given geographical region. The method is based on ambient seismic background noise measurements at the individual IMS seismic stations as well as on global distance correction terms for body wave magnitudes, which are calculated using the seismic reflectivity method. From our investigations we conclude that a global detection threshold of around mb 4.0 can be achieved using only stations from the primary seismic network, a clear latitudinal dependence for the detection threshold can be observed between northern and southern hemisphere. Including the seismic stations being part of the auxiliary seismic IMS network results in a slight improvement of global detection capability. However, including wave arrivals from distances greater than 120 degrees, mainly PKP-wave arrivals, leads to a significant improvement in average global detection capability. In special this leads to an improvement of the detection threshold on the southern hemisphere. We further investigate the dependence of the detection capability on spatial (latitude and longitude) and temporal (time) parameters, as well as on parameters such as source type and percentage of operational IMS stations.

  11. Seismic Energy Generation and Partitioning into Various Regional Phases from Different Seismic Sources in the Middle East Region

    Science.gov (United States)

    2007-09-20

    a), a 3C SP seismic station (b) and a sensor BlastMateIII, Oron quarry (c)............................... 9 Figure 7. Seismic Array MMAI (AS49) of... seismic stations of Jordan network at distance range 22-285 km (a), and at IMS array MMAI (AS49) at 350 km, BP filtered 2-8 Hz (b...sites and portable stations, inserts show detailed location of the tripartite array elements (st.6) and configuration of the explosion boreholes and

  12. Joint Inversion of Surface Waves Dispersion and Receiver Function at Cuba Seismic Stations

    International Nuclear Information System (INIS)

    Gonzalez, O'Leary; Moreno, Bladimir; Romanelli, Fabio; Panza, Giuliano F.

    2010-06-01

    Joint inversion of Rayleigh wave group velocity dispersion and receiver functions have been used to estimate the crust and upper mantle structure at eight seismic stations in Cuba. Receiver functions have been computed from teleseismic recordings of earthquakes at epicentral (angular) distances between 30 o and 90 o and Rayleigh wave group velocity dispersion have been taken from a surface-wave tomography study of the Caribbean area. The thickest crust (around 27 km) is found at Cascorro (CCC), Soroa (SOR), Moa (MOA) and Maisi (MAS) stations while the thinnest crust (around 18 km) is found at stations Rio Carpintero (RCC) and Guantanamo Bay (GTBY), in the southeastern of Cuba; this result is in agreement with the southward gradual thinning of the crust revealed by previous studies. The inversion shows a crystalline crust with S-wave velocity between 2.9 km/s and 3.9 km/s and at the crust-mantle transition zone the shear wave velocity varies from 3.9 km/s and 4.3 km/s. The lithospheric thickness varies from 74 km, in the youngest lithosphere, to 200 km in the middle of the Cuban island. Evidences of a subducted slab possibly belonging to the Caribbean plate are present below the stations Las Mercedes (LMG), RCC and GTBY and a thicker slab is present below the SOR station. (author)

  13. Feeling the Earth Shake… at School

    Science.gov (United States)

    Courboulex, F.; Berenguer, J.; Leputh, J.; Zodmi, B.; Tilquin, F.; Tartiere, M.; Ngo, O.; Mathias, L.; Moulié, F.; Virieux, J.; Larroque, C.; Douchain, J.; Nolet, G.; Bernard, P.; Arroucau, P.; Chlieh, M.; Deschamps, A.; Pillet, R.; Regnier, M.

    2009-12-01

    Earthquakes are both troubling and fascinating because of their suddenness and the terrible destruction they can wreak. However, a seismic wave cannot be touched, the Earth’s interior cannot be seen and, earthquakes cannot be predicted … By installing seismic stations in schools, the ‘Sismos à l’Ecole’ project enables teachers, children and students to: - measure and visualize seismic waves coming from anywhere in the world; - Obtain by themselves new results (location of the event, magnitude,depth of the Moho, shallow zones, etc …); - become more sensitive to natural hazard and especially seismic risk; - become more aware as citizens. The ‘Sismos à l’Ecole’ network includes 50 seismic stations in metropolitan France, the overseas departments and territories and several French high schools around the world (Australia, Venezuela, Turkey, Italy, Ecuador, Dominican Republic, Lebanon). All stations are digital, three-component stations, with a 50 Hz sampling frequency and are equipped with a sensitive broad-band seismometer. Data from earthquakes are gathered every night in a common database that is freely available to everyone through a web site (www.edusismo.org). On this website, teachers regularly propose new classroom activities that use the data they collected themselves. To reinforce the link between education and research, each teacher’s team has its own seismologist adviser (usually located in the laboratory that is closest to the school), whose role is mainly to answer the questions of teachers and to meet students. By getting familiar with scientific measurement, the student becomes personally involved and learns to master complex concepts in geophysics and the geosciences. The development of simple devices and the design of concrete experiments associated with an investigative approach all make it possible to instill in the students an appreciation for scientific thinking and process, and to create future citizens that are educated

  14. SISMIKO: emergency network deployment and data sharing for the 2016 central Italy seismic sequence

    Directory of Open Access Journals (Sweden)

    Milena Moretti

    2016-12-01

    Full Text Available At 01:36 UTC (03:36 local time on August 24th 2016, an earthquake Mw 6.0 struck an extensive sector of the central Apennines (coordinates: latitude 42.70° N, longitude 13.23° E, 8.0 km depth. The earthquake caused about 300 casualties and severe damage to the historical buildings and economic activity in an area located near the borders of the Umbria, Lazio, Abruzzo and Marche regions. The Istituto Nazionale di Geofisica e Vulcanologia (INGV located in few minutes the hypocenter near Accumoli, a small town in the province of Rieti. In the hours after the quake, dozens of events were recorded by the National Seismic Network (Rete Sismica Nazionale, RSN of the INGV, many of which had a ML > 3.0. The density and coverage of the RSN in the epicentral area meant the epicenter and magnitude of the main event and subsequent shocks that followed it in the early hours of the seismic sequence were well constrained. However, in order to better constrain the localizations of the aftershock hypocenters, especially the depths, a denser seismic monitoring network was needed. Just after the mainshock, SISMIKO, the coordinating body of the emergency seismic network at INGV, was activated in order to install a temporary seismic network integrated with the existing permanent network in the epicentral area. From August the 24th to the 30th, SISMIKO deployed eighteen seismic stations, generally six components (equipped with both velocimeter and accelerometer, with thirteen of the seismic station transmitting in real-time to the INGV seismic monitoring room in Rome. The design and geometry of the temporary network was decided in consolation with other groups who were deploying seismic stations in the region, namely EMERSITO (a group studying site-effects, and the emergency Italian strong motion network (RAN managed by the National Civil Protection Department (DPC. Further 25 BB temporary seismic stations were deployed by colleagues of the British Geological Survey

  15. The new 'Angeli di San Giuliano' School: a significant example of seismic isolation

    International Nuclear Information System (INIS)

    Clemente, P.; Buffarini, G.; Dolce, M.; Parducci, A.

    2009-01-01

    The new school in San Giuliano di Puglia has been built with a seismic base isolation system ensuring a safety degree that otherwise could not be obtained with traditional techniques. Due to its complex and irregular shape, the building also gives rise to some considerations about the design in seismic areas. [it

  16. Evaluation of the 3D high resolution seismic method at the Tournemire site around the IPSN experimental station

    International Nuclear Information System (INIS)

    Cabrera Nunez, J.

    2003-01-01

    The IPSN experimental station of Tournemire is localized at a 200 m depth inside an abandoned railway tunnel dug in a Jurassic clayey formation. The a priori knowledge of the existing geologic structures of the clayey formations allows to test the reliability of the 3D high resolution seismic survey technique and its capability to detect these structures and discontinuities. This test study is reported in this technical note. It comprises several steps: a bibliographic synthesis and a state-of-the-art of the 3D seismic survey technique, the construction of a velocity model for the different strata of the site, a simulation of the possible seismic response of these strata with respect to the velocities chosen, the processing of the data and finally their interpretation. (J.S.)

  17. Estimation of background noise level on seismic station using statistical analysis for improved analysis accuracy

    Science.gov (United States)

    Han, S. M.; Hahm, I.

    2015-12-01

    We evaluated the background noise level of seismic stations in order to collect the observation data of high quality and produce accurate seismic information. Determining of the background noise level was used PSD (Power Spectral Density) method by McNamara and Buland (2004) in this study. This method that used long-term data is influenced by not only innate electronic noise of sensor and a pulse wave resulting from stabilizing but also missing data and controlled by the specified frequency which is affected by the irregular signals without site characteristics. It is hard and inefficient to implement process that filters out the abnormal signal within the automated system. To solve these problems, we devised a method for extracting the data which normally distributed with 90 to 99% confidence intervals at each period. The availability of the method was verified using 62-seismic stations with broadband and short-period sensors operated by the KMA (Korea Meteorological Administration). Evaluation standards were NHNM (New High Noise Model) and NLNM (New Low Noise Model) published by the USGS (United States Geological Survey). It was designed based on the western United States. However, Korean Peninsula surrounded by the ocean on three sides has a complicated geological structure and a high population density. So, we re-designed an appropriate model in Korean peninsula by statistically combined result. The important feature is that secondary-microseism peak appeared at a higher frequency band. Acknowledgements: This research was carried out as a part of "Research for the Meteorological and Earthquake Observation Technology and Its Application" supported by the 2015 National Institute of Meteorological Research (NIMR) in the Korea Meteorological Administration.

  18. IEEE recommended practices for seismic qualification of Class 1E equipment for nuclear power generating stations

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    The IEEE has developed this document to provide direction for developing programs to seismically qualify Class 1E equipment for nuclear power generating stations. It supplements IEEE Std 323-1974, IEEE Standard for Qualifying Class 1E Equipment for Nuclear Power Generating Stations, which describes the basic requirements for equipment qualification. The Class 1E equipment to be qualified by produres or standards established by this document are of many forms, characteristics, and materials; therefore, the document presents many acceptable methods with the intent of permitting the user to make a judicious selection from among the various options. In making such a selection, the user should choose those that best meet a particular equipment's requirements. Further, in using this document as a specification for the purchase of equipment, the many options should also be recognized and the document invoked accordingly. It is recommended that the need for specific standards for the seismic qualifiction of particular kinds of equipment be evaluated by those responsible for such documents and that consideration be given to the application of particular methods from these documents which are most suitable

  19. Extraction of Pn seismic signals from air-gun shots recorded by the Cascadia Amphibious seismic experiment

    Science.gov (United States)

    Rathnayaka, S.; Gao, H.

    2017-12-01

    The goal of this study is to extract Pn (head wave) seismic waveforms recorded by both offshore and onshore (broadband and short period) seismic stations and evaluate the data quality. Two offshore active-source seismic experiments, MGL 1211 and MGL 1212, were conducted from 13th June to 24th July 2012, during the first year deployment of the Cascadia Initiative Amphibious Array. In total, we choose 110 ocean bottom seismometers and 209 inland stations that are located along the entire Cascadia subduction zone. We first remove the instrument response, and then explore the potential frequency ranges and the diurnal effect. We make the common receiver gathering for each seismic station and filter the seismic waveforms at multiple frequency bands, ranging from 3-5 Hz, 5-10 Hz, 10-20 Hz, to 20-40 Hz, respectively. To quantitatively evaluate the data quality, we calculate the signal-to-noise ratio (SNR) of the waveforms for usable stations that record clear Pn arrivals at multiple frequency bands. Our results show that most offshore stations located at deep water (>1.5 km) record clear air-gun shot signals at frequencies higher than 3 Hz and up to 550 km away from the source. For most stations located on the shallow continental shelf, the seismic recordings appear much noisier at all the frequencies compared to stations at deep water. Three general trends are observed for the SNR distribution; First, the SNR ratio increases from lower to higher frequency bands; Second, the ratio decreases with the increasing source-to-receiver distance; And third, the ratio increases from shallow to deep water. We also observe a rough negative relationship of the signal-to-noise ratio with the thickness of the marine sediment. Only 5 inland stations record clear air-gun shot arrivals up to 200 km away from the source. More detailed data quality analysis with more results will also be present.

  20. NCSRR digital seismic network in Romania

    International Nuclear Information System (INIS)

    Aldea, A.; Albota, E.; Demetriu, S.; Poiata, N.; Kashima, T.

    2007-01-01

    Digital seismic instrumentation donated by Japan International Cooperation Agency (JICA) to the National Center for Seismic Risk Reduction (NCSRR, Romania) allowed the installation in 2003 of a new Romanian seismic network. In 2005-2006 the network was developed by investments from NCSRR within the budget ensured by Ministry of Transports, Construction and Tourism (MTCT). The NCSRR seismic network contains three types of instrumentation: (i) free-field stations - outside the capital city Bucharest (8 accelerometers), (ii) instrumented buildings - in Bucharest (5 buildings), and (iii) stations with free-field and borehole sensors - in Bucharest (8 sites with ground surface sensor and sensors in 15 boreholes with depths up to 153 m). Since its installation, the NCSRR network recorded more than 170 seismic motions from 26 earthquakes with moment magnitudes ranging from 3.2 to 6.0. The seismic instrumentation was accompanied by investigations of ground conditions and site response: PS logging tests, single-station and array microtremor measurements. The development of seismic monitoring in Romania is a major contribution of JICA Project, creating the premises for a better understanding and modelling of earthquake ground motion, site effects and building response. (authors)

  1. Severity Classification of a Seismic Event based on the Magnitude-Distance Ratio Using Only One Seismological Station

    Directory of Open Access Journals (Sweden)

    Luis Hernán Ochoa Gutiérrez

    2014-07-01

    Full Text Available Seismic event characterization is often accomplished using algorithms based only on information received at seismological stations located closest to the particular event, while ignoring historical data received at those stations. These historical data are stored and unseen at this stage. This characterization process can delay the emergency response, costing valuable time in the mitigation of the adverse effects on the affected population. Seismological stations have recorded data during many events that have been characterized by classical methods, and these data can be used as previous "knowledge" to train such stations to recognize patterns. This knowledge can be used to make faster characterizations using only one three-component broadband station by applying bio-inspired algorithms or recently developed stochastic methods, such as kernel methods. We trained a Support Vector Machine (SVM algorithm with seismograph data recorded by INGEOMINAS's National Seismological Network at a three-component station located near Bogota, Colombia. As input model descriptors, we used the following: (1 the integral of the Fourier transform/power spectrum for each component, divided into 7 windows of 2 seconds and beginning at the P onset time, and (2 the ratio between the calculated logarithm of magnitude (Mb and epicentral distance. We used 986 events with magnitudes greater than 3 recorded from late 2003 to 2008. The algorithm classifies events with magnitude-distance ratios (a measure of the severity of possible damage caused by an earthquake greater than a background value. This value can be used to estimate the magnitude based on a known epicentral distance, which is calculated from the difference between P and S onset times. This rapid (< 20 seconds magnitude estimate can be used for rapid response strategies. The results obtained in this work confirm that many hypocentral parameters and a rapid location of a seismic event can be obtained using a few

  2. Seismic Search Engine: A distributed database for mining large scale seismic data

    Science.gov (United States)

    Liu, Y.; Vaidya, S.; Kuzma, H. A.

    2009-12-01

    The International Monitoring System (IMS) of the CTBTO collects terabytes worth of seismic measurements from many receiver stations situated around the earth with the goal of detecting underground nuclear testing events and distinguishing them from other benign, but more common events such as earthquakes and mine blasts. The International Data Center (IDC) processes and analyzes these measurements, as they are collected by the IMS, to summarize event detections in daily bulletins. Thereafter, the data measurements are archived into a large format database. Our proposed Seismic Search Engine (SSE) will facilitate a framework for data exploration of the seismic database as well as the development of seismic data mining algorithms. Analogous to GenBank, the annotated genetic sequence database maintained by NIH, through SSE, we intend to provide public access to seismic data and a set of processing and analysis tools, along with community-generated annotations and statistical models to help interpret the data. SSE will implement queries as user-defined functions composed from standard tools and models. Each query is compiled and executed over the database internally before reporting results back to the user. Since queries are expressed with standard tools and models, users can easily reproduce published results within this framework for peer-review and making metric comparisons. As an illustration, an example query is “what are the best receiver stations in East Asia for detecting events in the Middle East?” Evaluating this query involves listing all receiver stations in East Asia, characterizing known seismic events in that region, and constructing a profile for each receiver station to determine how effective its measurements are at predicting each event. The results of this query can be used to help prioritize how data is collected, identify defective instruments, and guide future sensor placements.

  3. Real-time detection and characterization of nuclear explosion using broadband analyses of regional seismic stations

    Science.gov (United States)

    Prastowo, T.; Madlazim

    2018-01-01

    This preliminary study aims to propose a new method of real-time detection and characterization of nuclear explosions by analyzing broadband seismic waveforms acquired from a network of regional seismic stations. Signal identification generated by a nuclear test was differentiated from natural sources of either earthquakes or other natural seismo-tectonic events by verifying crucial parameters, namely source depth, type of first motion, and P-wave domination of the broadband seismic wavesunder consideration. We examined and analyzed a recently hypothetical nuclear test performed by the North Koreangovernment that occurred on September 3, 2017 as a vital point to study. From spectral analyses, we found that the source of corresponding signals associated with detonations of the latest underground nuclear test was at a much shallower depth below the surface relatively compared with that of natural earthquakes, the suspected nuclear explosions produced compressional waves with radially directed outward from the source for their first motions, and the waves were only dominated by P-components. The results are then discussed in the context of potential uses of the proposed methodology for human-induced disaster early warning system and/or the need of rapid response purposes for minimizing the disaster risks.

  4. The Global Detection Capability of the IMS Seismic Network in 2013 Inferred from Ambient Seismic Noise Measurements

    Science.gov (United States)

    Gaebler, P. J.; Ceranna, L.

    2016-12-01

    All nuclear explosions - on the Earth's surface, underground, underwater or in the atmosphere - are banned by the Comprehensive Nuclear-Test-Ban Treaty (CTBT). As part of this treaty, a verification regime was put into place to detect, locate and characterize nuclear explosion testings at any time, by anyone and everywhere on the Earth. The International Monitoring System (IMS) plays a key role in the verification regime of the CTBT. Out of the different monitoring techniques used in the IMS, the seismic waveform approach is the most effective technology for monitoring nuclear underground testing and to identify and characterize potential nuclear events. This study introduces a method of seismic threshold monitoring to assess an upper magnitude limit of a potential seismic event in a certain given geographical region. The method is based on ambient seismic background noise measurements at the individual IMS seismic stations as well as on global distance correction terms for body wave magnitudes, which are calculated using the seismic reflectivity method. From our investigations we conclude that a global detection threshold of around mb 4.0 can be achieved using only stations from the primary seismic network, a clear latitudinal dependence for the detection thresholdcan be observed between northern and southern hemisphere. Including the seismic stations being part of the auxiliary seismic IMS network results in a slight improvement of global detection capability. However, including wave arrivals from distances greater than 120 degrees, mainly PKP-wave arrivals, leads to a significant improvement in average global detection capability. In special this leads to an improvement of the detection threshold on the southern hemisphere. We further investigate the dependence of the detection capability on spatial (latitude and longitude) and temporal (time) parameters, as well as on parameters such as source type and percentage of operational IMS stations.

  5. Seismic investigations for the Waste Isolation Pilot Plant

    International Nuclear Information System (INIS)

    Barrows, L.J.

    1984-01-01

    Evaporite rocks in the Delaware Basin in southeastern New Mexico are being investigated as a possible site for nuclear waste disposal. Seismic studies have been conducted to establish seismic design criteria and to investigate relations between seismicity and geologic structures. In the initial phase of this study, historical and available seismic data were interpreted with respect to geology. Local instrumentation became available in 1974 when New Mexico Tech installed and began operating a seismic station in the area. Data and interpretation for 1974 through 1979 have been published. In 1980 seismic monitoring of the Northern Delaware Basin was extended to include a six station network of self-contained radio-telemetered seismometers. 9 references, 13 figures

  6. Measurement of seismic moments at the RSTN station RSSD for NTS explosions

    International Nuclear Information System (INIS)

    Taylor, S.R.; Patton, H.J.

    1983-01-01

    We have estimated the seismic moment for two Nevada Test Site (NTS) explosions (Nebbiolo, 6/24/82; Atrisco, 8/5/82) at the Regional Seismic Test Network (RSTN) station in South Dakota (RSSD; distance from NTS approx. 1280 km). The moments are calculated from the vertical component mid-period channel for the Rayleigh waves and the merged mid- and short-period band for the P waves. The moment estimates from surface waves give values of 1.0 x 10 23 and 2.0 x 10 23 dyn-cm for Nebbiolo and Atrisco, respectively. The body-wave moments obtained at 0.5 Hz are approximately five times greater than those from surface waves and give values of 4.8 x 10 23 and 1.0 x 10 24 dyn-cm for Nebbiolo and Atrisco, respectively. The apparent discrepancy between the body and surface-wave moments can be resolved if there is overshoot (of 5:1) in the explosion source spectrum. As a check on the absolute value of the surface-wave moments, we compared them to moment values predicted from empirical moment-yield relationships for different emplacement media at NTS (Patton, 1983). We found that the agreement between observed and predicted values is satisfactory, within the measurement error on the moments at the one sigma level

  7. Fast Estimation of Epicentral Distance and Magnitude from a Single Three Component Seismic Station Using Machine Learning Techniques

    Science.gov (United States)

    Ochoa Gutierrez, L. H.; Niño, L. F.; Vargas-Jimenez, C. A.

    2013-05-01

    To minimize adverse effects originated by high magnitude earthquakes, early warning has become a powerful tool to anticipate a seismic wave arrival to an specific location, bringing opportune information to people and government agencies to initiate a fast response. To do this, a very fast and accurate characterization of the event must be done but this process is often made using seismograms recorded in at least four stations where processing time is usually greater than the wave arrival time to the interest area, mainly in seismological coarse networks. A faster process can be done if only one three component seismic station, the closest unsaturated station with respect to the epicenter, is used. Here, we present a Support Vector Regression algorithm which calculates Magnitude and Epicentral Distance using only five seconds of signal since P wave onset. This algorithm was trained with 36 records of historical earthquakes, where the input included regression parameters of an exponential function estimated by least squares, of the waveform envelope and the maximum value of the observed waveform for each component in a single station. A ten-fold Cross Validation was applied for a Normalized Polynomial Kernel obtaining the mean absolute error for different exponents and complexity parameters. The Magnitude could be estimated with 0.16 units of mean absolute error and the distance with an error of 7.5 km for distances within 60 to 120 km. This kind of algorithm is easy to implement in hardware and can be used directly in the field seismological sensor to make the broadcast of estimations of these values possible to generate fast decisions at seismological control centers, increasing the possibility of having an effective reaction.

  8. The monterey bay broadband ocean bottom seismic observatory

    Directory of Open Access Journals (Sweden)

    R. Uhrhammer

    2006-06-01

    Full Text Available We report on the installation of a long-term buried ocean-floor broadband seismic station (MOBB in Monterey Bay, California (USA, 40km off-shore, at a water depth of 1000 m. The station was installed in April 2002 using a ship and ROV, in a collaborative effort between the Monterey Bay Aquarium Research Institute (MBARI and the Berkeley Seismological Laboratory (BSL. The station is located on the western side of the San Gregorio Fault, a major fault in the San Andreas plate boundary fault system. In addition to a 3-component CMG-1T seismometer package, the station comprises a current meter and Differential Pressure Gauge, both sampled at high-enough frequency (1 Hz to allow the study of relations between background noise on the seismometers and ocean waves and currents. The proximity of several land-based broadband seismic stations of the Berkeley Digital Seismic Network allows insightful comparisons of land/ocean background seismic noise at periods relevant to regional and teleseismic studies. The station is currently autonomous. Recording and battery packages are exchanged every 3 months during scheduled one day dives. Ultimately, this station will be linked to shore using continuous telemetry (cable and/or buoy and will contribute to the earthquake notification system in Northern California. We present examples of earthquake and noise data recorded during the first 6 months of operation of MOBB. Lessons learned from these and continued recordings will help understand the nature and character of background noise in regional off-shore environments and provide a reference for the installation of future off-shore temporary and permanent broadband seismic stations.

  9. Seismic noise level variation in South Korea

    Science.gov (United States)

    Sheen, D.; Shin, J.

    2008-12-01

    The variations of seismic background noise in South Korea have been investigated by means of power spectral analysis. The Korea Institute of Geoscience and Mineral Resources (KIGAM) and the Korea Meteorological Administation (KMA) have national wide seismic networks in South Korea, and, in the end of 2007, there are 30 broadband stations which have been operating for more than a year. In this study, we have estimated the power spectral density of seismic noise for 30 broadband stations from 2005 to 2007. Since we estimate PSDs from a large dataset of continuous waveform in this study, a robust PSD estimate of McNamara and Buland (2004) is used. In the frequency range 1-5 Hz, the diurnal variations of noise are observed at most of stations, which are especially larger at coastal stations and at insular than at inland. Some stations shows daily difference of diurnal variations, which represents that cultural activities contribute to the noise level of a station. The variation of number of triggered stations, however, shows that cultural noise has little influence on the detection capability of seismic network in South Korea. Seasonal variations are observed well in the range 0.1-0.5 Hz, while much less found in the frequency range 1-5 Hz. We observed that strong peaks in the range 0.1-0.5 Hz occur at the summer when Pacific typhoons are close to the Korean Peninsula.

  10. Monitoring Instrument Performance in Regional Broadband Seismic Network Using Ambient Seismic Noise

    Science.gov (United States)

    Ye, F.; Lyu, S.; Lin, J.

    2017-12-01

    In the past ten years, the number of seismic stations has increased significantly, and regional seismic networks with advanced technology have been gradually developed all over the world. The resulting broadband data help to improve the seismological research. It is important to monitor the performance of broadband instruments in a new network in a long period of time to ensure the accuracy of seismic records. Here, we propose a method that uses ambient noise data in the period range 5-25 s to monitor instrument performance and check data quality in situ. The method is based on an analysis of amplitude and phase index parameters calculated from pairwise cross-correlations of three stations, which provides multiple references for reliable error estimates. Index parameters calculated daily during a two-year observation period are evaluated to identify stations with instrument response errors in near real time. During data processing, initial instrument responses are used in place of available instrument responses to simulate instrument response errors, which are then used to verify our results. We also examine feasibility of the tailing noise using data from stations selected from USArray in different locations and analyze the possible instrumental errors resulting in time-shifts used to verify the method. Additionally, we show an application that effects of instrument response errors that experience pole-zeros variations on monitoring temporal variations in crustal properties appear statistically significant velocity perturbation larger than the standard deviation. The results indicate that monitoring seismic instrument performance helps eliminate data pollution before analysis begins.

  11. Toward 2D Seismic Wavefield Monitoring: Seismic Gradiometry for Long-Period Seismogram and Short-Period Seismogram Envelope applied to the Hi-net Array

    Science.gov (United States)

    Maeda, T.; Nishida, K.; Takagi, R.; Obara, K.

    2015-12-01

    The high-sensitive seismograph network Japan (Hi-net) operated by National Research Institute for Earth Science and Disaster Prevention (NIED) has about 800 stations with average separation of 20 km. We can observe long-period seismic wave propagation as a 2D wavefield with station separations shorter than wavelength. In contrast, short-period waves are quite incoherent at stations, however, their envelope shapes resemble at neighbor stations. Therefore, we may be able to extract seismic wave energy propagation by seismogram envelope analysis. We attempted to characterize seismic waveform at long-period and its envelope at short-period as 2D wavefield by applying seismic gradiometry. We applied the seismic gradiometry to a synthetic long-period (20-50s) dataset prepared by numerical simulation in realistic 3D medium at the Hi-net station layout. Wave amplitude and its spatial derivatives are estimated by using data at nearby stations. The slowness vector, the radiation pattern and the geometrical spreading are extracted from estimated velocity, displacement and its spatial derivatives. For short-periods at shorter than 1 s, seismogram envelope shows temporal and spatial broadening through scattering by medium heterogeneity. It is expected that envelope shape may be coherent among nearby stations. Based on this idea, we applied the same method to the time-integration of seismogram envelope to estimate its spatial derivatives. Together with seismogram envelope, we succeeded in estimating the slowness vector from the seismogram envelope as well as long-period waveforms by synthetic test, without using phase information. Our preliminarily results show that the seismic gradiometry suits the Hi-net to extract wave propagation characteristics both at long and short periods. This method is appealing that it can estimate waves at homogeneous grid to monitor seismic wave as a wavefield. It is promising to obtain phase velocity variation from direct waves, and to grasp wave

  12. Seismic risk evaluation for high voltage air insulated substations

    International Nuclear Information System (INIS)

    Camensig, Carlo; Bresesti, Luca; Clementel, Stefano; Salvetti, Maurizio

    1997-01-01

    This paper describes the results of the analytical and experimental activities performed by ISMES for the evaluation of the structural reliability of electrical substations with respect to seismic events. In the following, the reference station is described along with the methods used to define the site seismic input, the analytical and experimental evaluation of the components' fragility curves and the whole station seismic risk evaluation

  13. Very Fast Estimation of Epicentral Distance and Magnitude from a Single Three Component Seismic Station Using Machine Learning Techniques

    Science.gov (United States)

    Ochoa Gutierrez, L. H.; Niño Vasquez, L. F.; Vargas-Jimenez, C. A.

    2012-12-01

    To minimize adverse effects originated by high magnitude earthquakes, early warning has become a powerful tool to anticipate a seismic wave arrival to an specific location and lets to bring people and government agencies opportune information to initiate a fast response. To do this, a very fast and accurate characterization of the event must be done but this process is often made using seismograms recorded in at least 4 stations where processing time is usually greater than the wave travel time to the interest area, mainly in coarse networks. A faster process can be done if only one three component seismic station is used that is the closest unsaturated station respect to the epicenter. Here we present a Support Vector Regression algorithm which calculates Magnitude and Epicentral Distance using only 5 seconds of signal since P wave onset. This algorithm was trained with 36 records of historical earthquakes where the input were regression parameters of an exponential function estimated by least squares, corresponding to the waveform envelope and the maximum value of the observed waveform for each component in one single station. A 10 fold Cross Validation was applied for a Normalized Polynomial Kernel obtaining the mean absolute error for different exponents and complexity parameters. Magnitude could be estimated with 0.16 of mean absolute error and the distance with an error of 7.5 km for distances within 60 to 120 km. This kind of algorithm is easy to implement in hardware and can be used directly in the field station to make possible the broadcast of estimations of this values to generate fast decisions at seismological control centers, increasing the possibility to have an effective reactiontribute and Descriptors calculator for SVR model training and test

  14. Keeping focus on earthquakes at school for seismic risk mitigation of the next generations

    Science.gov (United States)

    Saraò, Angela; Barnaba, Carla; Peruzza, Laura

    2013-04-01

    The knowledge of the seismic history of its own territory, the understanding of physical phenomena in response to an earthquake, the changes in the cultural heritage following a strong earthquake, the learning of actions to be taken during and after an earthquake, are piece of information that contribute to keep focus on the seismic hazard and to implement strategies for seismic risk mitigation. The training of new generations, today more than ever subject to rapid forgetting of past events, becomes therefore a key element to increase the perception that earthquakes happened and can happen at anytime and that mitigation actions are the only means to ensure the safety and to reduce damages and human losses. Since several years our institute (OGS) is involved in activities to raise awareness of education on earthquake. We aim to implement education programs with the goal of addressing a critical approach to seismic hazard reduction, differentiating the types of activities according to the age of the students. However, being such kind of activity unfunded, we can act at now only on a very limited number of schools per year. To be effective, the inclusion of the seismic risk issues in school curricula requires specific time and appropriate approaches when planning activities. For this reason, we involve also the teachers as proponents of activities and we encourage them to keep alive memories and discussion on earthquake in the classes. During the past years we acted mainly in the schools of the Friuli Venezia Giulia area (NE Italy), that is an earthquake prone area struck in 1976 by a destructive seismic event (Ms=6.5). We organized short training courses for teachers, we lectured classes, and we led laboratory activities with students. Indeed, being well known that students enjoy classes more when visual and active learning are joined, we propose a program that is composed by seminars, demonstrations and hands-on activities in the classrooms; for high school students

  15. Seismic alarm system for Ignalina nuclear power plant

    International Nuclear Information System (INIS)

    Wieland, M.; Griesser, L.; Austin, G.E.; Tiurin, S.; Kuendig, C.

    2001-01-01

    A seismic alarm system will be installed at the Ignalina Nuclear Power Plant (INPP) in Lithuania. There are two reactors, both RMBK 1500 MW units. Each reactor is a water cooled, graphite moderated, channel type reactor. INPP has the most advanced version of the RMBK reactor design series. The first and second units of INPP went into service at the end of 1983 and in August 1987 respectively. Their design lifetime is approx. 30 years. The various buildings and plant have been designed for two earthquake levels, that is the design earthquake and the maximum possible earthquake with peak ground accelerations ranging from 1.2% to 10% of the acceleration due to gravity. Certain parts of the buildings and some of the equipment of the first and second units do not comply with Western seismic standards. As seismic strengthening of the existing buildings and equipment is not feasible economically, a reactor protection system based on an earthquake early warning system was recommended. This system essentially consists of six seismic stations encircling INPP at a radial distance of approx. 30 km and a seventh station at INPP. Each station includes three seismic substations each 500 m apart. The ground motion at each station is measured continuously by three accelerometers and one seismometer. Data is transmitted via telemetry to the control centre at INPP. Early warning alarms are generated if a seismic threshold is exceeded. This paper discusses the characteristics of INPP, the seismic alarm system presently under construction and the experience with other early warning and seismic alarm systems. (author)

  16. Determination of Rayleigh wave ellipticity using single-station and array-based processing of ambient seismic noise

    Science.gov (United States)

    Workman, Eli Joseph

    We present a single-station method for the determination of Rayleigh wave ellipticity, or Rayleigh wave horizontal to vertical amplitude ratio (H/V) using Frequency Dependent Polarization Analysis (FDPA). This procedure uses singular value decomposition of 3-by-3 spectral covariance matrices over 1-hr time windows to determine properties of the ambient seismic noise field such as particle motion and dominant wave-type. In FPDA, if the noise is mostly dominated by a primary singular value and the phase difference is roughly 90° between the major horizontal axis and the vertical axis of the corresponding singular vector, we infer that Rayleigh waves are dominant and measure an H/V ratio for that hour and frequency bin. We perform this analysis for all available data from the Earthscope Transportable Array between 2004 and 2014. We compare the observed Rayleigh wave H/V ratios with those previously measured by multicomponent, multistation noise cross-correlation (NCC), as well as classical noise spectrum H/V ratio analysis (NSHV). At 8 sec the results from all three methods agree, suggesting that the ambient seismic noise field is Rayleigh wave dominated. Between 10 and 30 sec, while the general pattern agrees well, the results from FDPA and NSHV are persistently slightly higher ( 2%) and significantly higher (>20%), respectively, than results from the array-based NCC. This is likely caused by contamination from other wave types (i.e., Love waves, body waves, and tilt noise) in the single station methods, but it could also reflect a small, persistent error in NCC. Additionally, we find that the single station method has difficulty retrieving robust Rayleigh wave H/V ratios within major sedimentary basins, such as the Williston Basin and Mississippi Embayment, where the noise field is likely dominated by reverberating Love waves.

  17. New Observations of Seismic Group Velocities in the Western Solomon Islands from Cross-Correlation of Ambient Seismic Noise

    Science.gov (United States)

    Ku, C. S.; You, S. H.; Kuo, Y. T.; Huang, B. S.; Wu, Y. M.; Chen, Y. G.; Taylor, F. W.

    2015-12-01

    A MW 8.1 earthquake occurred on 1 April 2007 in the western Solomon Islands. Following this event, a damaging tsunami was induced and hit the Island Gizo where the capital city of Western Province of Solomon Islands located. Several buildings of this city were destroyed and several peoples lost their lives during this earthquake. However, during this earthquake, no near source seismic instrument has been installed in this region. The seismic evaluations for the aftershock sequence, the possible earthquake early warning and tsunami warning were unavailable. For the purpose of knowing more detailed information about seismic activity in this region, we have installed 9 seismic stations (with Trillium 120PA broadband seismometer and Q330S 24bit digitizer) around the rupture zone of the 2007 earthquake since September of 2009. Within a decade, it has been demonstrated both theoretically and experimentally that the Green's function or impulse response between two seismic stations can be retrieved from the cross-correlation of ambient noise. In this study, 6 stations' observations which are more complete during 2011/10 ~ 2012/12 period, were selected for the purpose of the cross-correlation analysis of ambient seismic noise. The group velocities at period 2-20 seconds of 15 station-pairs were extracted by using multiple filter technique (MFT) method. The analyzed results of this study presented significant results of group velocities with higher frequency contents than other studies (20-60 seconds in usually cases) and opened new opportunities to study the shallow crustal structure of the western Solomon Islands.

  18. Data processing of natural and induced events recorded at the seismic station Ostrava-Kr¨¢sn¨¦ Pole (OKC)

    OpenAIRE

    Nov¨¢k Josef; Rušajov¨¢ Jana; Holub Karel; Kejzl¨ªk Jarom¨ªr

    2001-01-01

    The operation of the seismic station Ostrava-Kr¨¢sn¨¦ Pole (OKC) (¦Õ = 49.8352¡ãN; ¦Ë = 18.1422¡ãE) which is situated at present in an experimental gallery nearby the Ostrava planetarium started in the year 1983 being equiped initially by analogue instrumentation. Modernization of instrumentation at the station was aimed at the installation of a new digital data acquisition system and the respective software packages for data interpretation and transmission.Data acquisition system VISTEC is b...

  19. Improving the Detectability of the Catalan Seismic Network for Local Seismic Activity Monitoring

    Science.gov (United States)

    Jara, Jose Antonio; Frontera, Tànit; Batlló, Josep; Goula, Xavier

    2016-04-01

    The seismic survey of the territory of Catalonia is mainly performed by the regional seismic network operated by the Cartographic and Geologic Institute of Catalonia (ICGC). After successive deployments and upgrades, the current network consists of 16 permanent stations equipped with 3 component broadband seismometers (STS2, STS2.5, CMG3ESP and CMG3T), 24 bits digitizers (Nanometrics Trident) and VSAT telemetry. Data are continuously sent in real-time via Hispasat 1D satellite to the ICGC datacenter in Barcelona. Additionally, data from other 10 stations of neighboring areas (Spain, France and Andorra) are continuously received since 2011 via Internet or VSAT, contributing both to detect and to locate events affecting the region. More than 300 local events with Ml ≥ 0.7 have been yearly detected and located in the region. Nevertheless, small magnitude earthquakes, especially those located in the south and south-west of Catalonia may still go undetected by the automatic detection system (DAS), based on Earthworm (USGS). Thus, in order to improve the detection and characterization of these missed events, one or two new stations should be installed. Before making the decision about where to install these new stations, the performance of each existing station is evaluated taking into account the fraction of detected events using the station records, compared to the total number of events in the catalogue, occurred during the station operation time from January 1, 2011 to December 31, 2014. These evaluations allow us to build an Event Detection Probability Map (EDPM), a required tool to simulate EDPMs resulting from different network topology scenarios depending on where these new stations are sited, and becoming essential for the decision-making process to increase and optimize the event detection probability of the seismic network.

  20. Real-time monitoring of seismic data using satellite telemetry

    Directory of Open Access Journals (Sweden)

    L. Merucci

    1997-06-01

    Full Text Available This article describes the ARGO Satellite Seismic Network (ARGO SSN as a reliable system for monitoring, collection, visualisation and analysis of seismic and geophysical low-frequency data, The satellite digital telemetry system is composed of peripheral geophysical stations, a centraI communications node (master sta- tion located in CentraI Italy, and a data collection and processing centre located at ING (Istituto Nazionale di Geofisica, Rome. The task of the peripheral stations is to digitalise and send via satellite the geophysical data collected by the various sensors to the master station. The master station receives the data and forwards them via satellite to the ING in Rome; it also performs alI the monitoring functions of satellite communications. At the data collection and processing centre of ING, the data are received and analysed in real time, the seismic events are identified and recorded, the low-frequency geophysical data are stored. In addition, the generaI sta- tus of the satellite network and of each peripheral station connected, is monitored. The procedure for analysjs of acquired seismic signals allows the automatic calculation of local magnitude and duration magnitude The communication and data exchange between the seismic networks of Greece, Spain and Italy is the fruit of a recent development in the field of technology of satellite transmission of ARGO SSN (project of European Community "Southern Europe Network for Analysis of Seismic Data"

  1. SIG-VISA: Signal-based Vertically Integrated Seismic Monitoring

    Science.gov (United States)

    Moore, D.; Mayeda, K. M.; Myers, S. C.; Russell, S.

    2013-12-01

    Traditional seismic monitoring systems rely on discrete detections produced by station processing software; however, while such detections may constitute a useful summary of station activity, they discard large amounts of information present in the original recorded signal. We present SIG-VISA (Signal-based Vertically Integrated Seismic Analysis), a system for seismic monitoring through Bayesian inference on seismic signals. By directly modeling the recorded signal, our approach incorporates additional information unavailable to detection-based methods, enabling higher sensitivity and more accurate localization using techniques such as waveform matching. SIG-VISA's Bayesian forward model of seismic signal envelopes includes physically-derived models of travel times and source characteristics as well as Gaussian process (kriging) statistical models of signal properties that combine interpolation of historical data with extrapolation of learned physical trends. Applying Bayesian inference, we evaluate the model on earthquakes as well as the 2009 DPRK test event, demonstrating a waveform matching effect as part of the probabilistic inference, along with results on event localization and sensitivity. In particular, we demonstrate increased sensitivity from signal-based modeling, in which the SIGVISA signal model finds statistical evidence for arrivals even at stations for which the IMS station processing failed to register any detection.

  2. Romanian seismic network

    International Nuclear Information System (INIS)

    Ionescu, Constantin; Rizescu, Mihaela; Popa, Mihaela; Grigore, Adrian

    2000-01-01

    The research in the field of seismology in Romania is mainly carried out by the National Institute for Earth Physics (NIEP). The NIEP activities are mainly concerned with the fundamental research financed by research contracts from public sources and the maintenance and operation of the Romanian seismic network. A three stage seismic network is now operating under NIEP, designed mainly to monitor the Vrancea seismic region in a magnitude range from microearthquakes to strong events: - network of 18 short-period seismometers (S13); - Teledyne Geotech Instruments (Texas); - network of 7 stations with local digital recording (PCM-5000) on magnetic tape, made up of, S13 geophone (T=2 s) on vertical component and SH1 geophone (T=5 s) on horizontal components; - network of 28 SMA-1 accelerometers and 30 digital accelerometers (Kinemetrics - K2) installed in the free field conditions in the framework of the joint German-Romanian cooperation program (CRC); the K2 instruments cover a magnitude range from 1.4 to 8.0. Since 1994, MLR (Muntele Rosu) station has become part of the GEOFON network and was provided with high performance broad band instruments. At Bucharest and Timisoara data centers, an automated and networked seismological system performs the on-line digital acquisition and processing of the telemetered data. Automatic processing includes discrimination between local and distant seismic events, earthquake location and magnitude computation, and source parameter determination for local earthquakes. The results are rapidly distributed via Internet, to several seismological services in Europe and USA, to be used in the association/confirmation procedures. Plans for new developments of the network include the upgrade from analog to digital telemetry and new stations for monitoring local seismicity. (authors)

  3. Seismic and Geodetic Monitoring of the Nicoya, Costa Rica, Seismic Gap

    Science.gov (United States)

    Protti, M.; Gonzalez, V.; Schwartz, S.; Dixon, T.; Kato, T.; Kaneda, Y.; Simila, G.; Sampson, D.

    2007-05-01

    The Nicoya segment of the Middle America Trench has been recognized as a mature seismic gap with potential to generate a large earthquake in the near future (it ruptured with large earthquakes in 1853, 1900 and 1950). Low level of background seismicity and fast crustal deformation of the forearc are indicatives of strong coupling along the plate interface. Given its high seismic potential, the available data and especially the fact that the Nicoya peninsula extends over large part of the rupture area, this gap was selected as one of the two sites for a MARGINS-SEIZE experiment. With the goal of documenting the evolution of loading and stress release along this seismic gap, an international effort involving several institutions from Costa Rica, the United States and Japan is being carried out for over a decade in the region. This effort involves the installation of temporary and permanent seismic and geodetic networks. The seismic network includes short period, broad band and strong motion instruments. The seismic monitoring has provided valuable information on the geometry and characteristics of the plate interface. The geodetic network includes temporary and permanent GPS stations as well as surface and borehole tiltmeters. The geodetic networks have helped quantify the extend and degree of coupling. A continuously recording, three- station GPS network on the Nicoya Peninsula, Costa Rica, recorded what we believe is the first slow slip event observed along the plate interface of the Costa Rica subduction zone. We will present results from these monitoring networks. Collaborative international efforts are focused on expanding these seismic and geodetic networks to provide improved resolution of future creep events, to enhanced understanding of the mechanical behavior of the Nicoya subduction segment of the Middle American Trench and possibly capture the next large earthquake and its potential precursor deformation.

  4. Improving Station Performance by Building Isolation Walls in the Tunnel

    Science.gov (United States)

    Jia, Yan; Horn, Nikolaus; Leohardt, Roman

    2014-05-01

    Conrad Observatory is situated far away from roads and industrial areas on the Trafelberg in Lower Austria. At the end of the seismic tunnel, the main seismic instrument of the Observatory with a station code CONA is located. This station is one of the most important seismic stations in the Austrian Seismic Network (network code OE). The seismic observatory consists of a 145m long gallery and an underground laboratory building with several working areas. About 25 meters away from the station CONA, six temporary seismic stations were implemented for research purposes. Two of them were installed with the same equipment as CONA, while the remaining four stations were set up with digitizers having lower noise and higher resolution (Q330HR) and sensors with the same type (STS-2). In order to prevent possible disturbances by air pressure and temperature fluctuation, three walls were built inside of the tunnel. The first wall is located ca 63 meters from the tunnel entrance, while a set of double walls with a distance of 1.5 meters is placed about 53 meters from the first isolation wall but between the station CONA and the six temporary stations. To assess impact of the isolation walls on noise reduction and detection performance, investigations are conducted in two steps. The first study is carried out by comparing the noise level and detection performance between the station CONA behind the double walls and the stations in front of the double walls for verifying the noise isolation by the double walls. To evaluate the effect of the single wall, station noise level and detection performance were studied by comparing the results before and after the installation of the wall. Results and discussions will be presented. Additional experiment is conducted by filling insulation material inside of the aluminium boxes of the sensors (above and around the sensors). This should help us to determine an optimal insulation of the sensors with respect to pressure and temperature

  5. Seismic excitation by space shuttles

    Science.gov (United States)

    Kanamori, H.; Mori, J.; Sturtevant, B.; Anderson, D.L.; Heaton, T.

    1992-01-01

    Shock waves generated by the space shuttles Columbia (August 13, 1989), Atlantis (April 11, 1991) and Discovery (September 18, 1991) on their return to Edwards Air Force Base, California, were recorded by TERRAscope (Caltech's broadband seismic network), the Caltech-U.S.G.S Southern California Seismic Network (SCSN), and the University of Southern California (USC) Los Angeles Basin Seismic Network. The spatial pattern of the arrival times exhibits hyperbolic shock fronts from which the path, velocity and altitude of the space shuttle could be determined. The shock wave was acoustically coupled to the ground, converted to a seismic wave, and recorded clearly at the broadband TERRAscope stations. The acoustic coupling occurred very differently depending on the conditions of the Earth's surface surrounding the station. For a seismic station located on hard bedrock, the shock wave (N wave) was clearly recorded with little distortion. Aside from the N wave, very little acoustic coupling of the shock wave energy to the ground occurred at these sites. The observed N wave record was used to estimate the overpressure of the shock wave accurately; a pressure change of 0.5 to 2.2 mbars was obtained. For a seismic station located close to the ocean or soft sedimentary basins, a significant amount of shock wave energy was transferred to the ground through acoustic coupling of the shock wave and the oceanic Rayleigh wave. A distinct topography such as a mountain range was found effective to couple the shock wave energy to the ground. Shock wave energy was also coupled to the ground very effectively through large man made structures such as high rise buildings and offshore oil drilling platforms. For the space shuttle Columbia, in particular, a distinct pulse having a period of about 2 to 3 seconds was observed, 12.5 s before the shock wave, with a broadband seismograph in Pasadena. This pulse was probably excited by the high rise buildings in downtown Los Angeles which were

  6. Station History Of The Seismic Station In Ahmadu Bello University ...

    African Journals Online (AJOL)

    Dominants in the selected events are events from Meditterranian, East Kazakhstan, India/Burma/China, South and Central America and North Ascension island regions. The limited number of events reporting at the station was due to low operational gain at the station which permitted only events whose magnitudes are ...

  7. Using Seismic Interferometry to Investigate Seismic Swarms

    Science.gov (United States)

    Matzel, E.; Morency, C.; Templeton, D. C.

    2017-12-01

    Seismicity provides a direct means of measuring the physical characteristics of active tectonic features such as fault zones. Hundreds of small earthquakes often occur along a fault during a seismic swarm. This seismicity helps define the tectonically active region. When processed using novel geophysical techniques, we can isolate the energy sensitive to the fault, itself. Here we focus on two methods of seismic interferometry, ambient noise correlation (ANC) and the virtual seismometer method (VSM). ANC is based on the observation that the Earth's background noise includes coherent energy, which can be recovered by observing over long time periods and allowing the incoherent energy to cancel out. The cross correlation of ambient noise between a pair of stations results in a waveform that is identical to the seismogram that would result if an impulsive source located at one of the stations was recorded at the other, the Green function (GF). The calculation of the GF is often stable after a few weeks of continuous data correlation, any perturbations to the GF after that point are directly related to changes in the subsurface and can be used for 4D monitoring.VSM is a style of seismic interferometry that provides fast, precise, high frequency estimates of the Green's function (GF) between earthquakes. VSM illuminates the subsurface precisely where the pressures are changing and has the potential to image the evolution of seismicity over time, including changes in the style of faulting. With hundreds of earthquakes, we can calculate thousands of waveforms. At the same time, VSM collapses the computational domain, often by 2-3 orders of magnitude. This allows us to do high frequency 3D modeling in the fault region. Using data from a swarm of earthquakes near the Salton Sea, we demonstrate the power of these techniques, illustrating our ability to scale from the far field, where sources are well separated, to the near field where their locations fall within each other

  8. Multichannel long period seismic data acquisition system

    International Nuclear Information System (INIS)

    Kolvankar, V.G.; Rao, D.S.

    1990-01-01

    This paper discusses the specifications and performance of an eight channel long period seismic digital data acquisition system, which is developed and installed at Seismic Array Station, Gauribidanur, Karnataka State. The paper describes how these data in an unedited form are recorded on a single track of magnetic tape inter-mittantly, which has resulted in recording of 50 days data on a single tapespool. A time indexing technique which enables quick access to any desired portion of a recorded tape is also discussed. Typical examples of long period seismic event signals recorded by this system are also illustrated. Various advantages, the system provides over the analog multichannel instrumentation tape recording system, operating at Seismic Array Station for th e last two decades, are also discussed. (author). 7 figs

  9. Seismic Tomography in Reykjanes , SW Iceland

    NARCIS (Netherlands)

    Jousset, Philippe; Blanck, Hanna; Franke, Steven; Metz, M.; Águstsson, K.; Verdel, Arie; Ryberg, T.; Hersir, Gylfi Páll; Weemstra, C.; Bruhn, D.F.; Flovenz, Olafur G

    2016-01-01

    We present tomographic results obtained around geothermal reservoirs using seismic data recorded both on-land Reykjanes, SW-Iceland and offshore along Reykjanes Ridge. We gathered records from a network of 83 seismic stations (including 21 Ocean Bottom Seismometers) deployed between April 2014 and

  10. Evolution and strengthening of the Calabrian Regional Seismic Network during the Pollino sequence

    Science.gov (United States)

    D'Alessandro, Antonino; Gervasi, Anna; Guerra, Ignazio

    2013-04-01

    In the last three years the Calabria-Lucania border area is affected by an intense seismic activity generated by the activation of geological structures which be seat of clusters of microearthquakes, with energy release sufficient to be felt and to generate alarm and bother. Besides to the historical memory of the inhabitants of Mormanno (the town most affected of macroseismic effects) there are some historical documents that indicate the occurrence of a similar seismic crisis in 1888. A more recent seismic sequence, the first monitored by seismic instruments, occurred in 1973-1974. In the last case, the activity started in early 2010 and is still ongoing. The two shocks of ML = 4.3 and 5.0 and the the very long time duration differs this crisis from the previous ones. Given this background, in 1981 was installed at Mormanno a seismic station (MMN) belonging to Regional Seismic Network of the University of Calabria (RSRC), now also a station of the Italian National Seismic Network of the Istituto Nazionale di Geofisica Vulcanolgia (INSN-INGV). This seismic station made it possible to follow the evolution of seismicity in this area and in particular the progressive increase in seismic activity started in 2010. Since 2010, some 3D stand-alone, was installed by the University of Calabria. Further stations of INGV were installed in November 2011 after a sharp increase of the energy release and subsequently by the INGV and the GeoForschungsZentrum (Potsdam) after the main shock of the whole sequence. Seismic networks are powerful tools for understanding active tectonic processes in a monitored seismically active region. However, the optimal monitoring of a seismic region requires the assessment of the seismic network capabilities to identify seismogenic areas that are not adequately covered and to quantify measures that will allow the network improvement. In this paper we examine in detail the evolution and the strengthening of the RSRC in the last years analyzing the

  11. Data quality control and tools in passive seismic experiments exemplified on the Czech broadband seismic pool MOBNET in the AlpArray collaborative project

    Science.gov (United States)

    Vecsey, Luděk; Plomerová, Jaroslava; Jedlička, Petr; Munzarová, Helena; Babuška, Vladislav; AlpArray Working Group

    2017-12-01

    This paper focuses on major issues related to the data reliability and network performance of 20 broadband (BB) stations of the Czech (CZ) MOBNET (MOBile NETwork) seismic pool within the AlpArray seismic experiments. Currently used high-resolution seismological applications require high-quality data recorded for a sufficiently long time interval at seismological observatories and during the entire time of operation of the temporary stations. In this paper we present new hardware and software tools we have been developing during the last two decades while analysing data from several international passive experiments. The new tools help to assure the high-quality standard of broadband seismic data and eliminate potential errors before supplying data to seismological centres. Special attention is paid to crucial issues like the detection of sensor misorientation, timing problems, interchange of record components and/or their polarity reversal, sensor mass centring, or anomalous channel amplitudes due to, for example, imperfect gain. Thorough data quality control should represent an integral constituent of seismic data recording, preprocessing, and archiving, especially for data from temporary stations in passive seismic experiments. Large international seismic experiments require enormous efforts from scientists from different countries and institutions to gather hundreds of stations to be deployed in the field during a limited time period. In this paper, we demonstrate the beneficial effects of the procedures we have developed for acquiring a reliable large set of high-quality data from each group participating in field experiments. The presented tools can be applied manually or automatically on data from any seismic network.

  12. Lawrence Livermore National Laboratory seismic yield determination for the NPE

    Energy Technology Data Exchange (ETDEWEB)

    Rohrer, R. [Lawrence Livermore National Lab., CA (United States)

    1994-12-31

    The Lawrence Livermore National Laboratory recorded seismic signals from the Non-Proliferation experiment at the Nevada Test Site on September 22, 1993, at seismic stations near Mina, Nevada; Kanab Utah; Landers, California; and Elko, Nevada. Yields were calculated from these recorded seismic amplitudes at the stations using statistical amplitude- yield regression curves from earlier nuclear experiments performed near the Non-Proliferation experiment. The weighted seismic yield average using these amplitudes is 1.9 kt with a standard deviation of 19%. The calibrating experiments were nuclear, so this yield is equivalent to a 1.9-kt nuclear experiment.

  13. Hanford quarterly seismic report - 97B seismicity on and near the Hanford Site, Pasco Basin, Washington, January 1, 1997--March 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Hartshorn, D.C.; Reidel, S.P.

    1997-05-01

    Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the U.S. Department of Energy and contractors. The staff also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for activities ranging from waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organizations works with the Hanford Site Emergency Services Organization to provide assistance in the event of an earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (EWRN) consist of 41 individual sensor sites and 15 radio relay sites maintained by the Seismic Monitoring staff. Most stations and five relay sites are solar powered. The operational rate for the second quarter of FY97 for stations in the HSN was 97.23% and for stations of the EWRN was 99.93%. For fiscal year (FY) 1997 second quarter (97B), the acquisition computer triggered two hundred and forth-eight times. Of these triggers three were local earthquakes: one in the pre-basalt sediments, and two in the crystalline basement. The geologic and tectonic environments are discussed in the report.

  14. Hanford quarterly seismic report - 97B seismicity on and near the Hanford Site, Pasco Basin, Washington, January 1, 1997 - March 31, 1997

    International Nuclear Information System (INIS)

    Hartshorn, D.C.; Reidel, S.P.

    1997-05-01

    Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the U.S. Department of Energy and contractors. The staff also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for activities ranging from waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organizations works with the Hanford Site Emergency Services Organization to provide assistance in the event of an earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (EWRN) consist of 41 individual sensor sites and 15 radio relay sites maintained by the Seismic Monitoring staff. Most stations and five relay sites are solar powered. The operational rate for the second quarter of FY97 for stations in the HSN was 97.23% and for stations of the EWRN was 99.93%. For fiscal year (FY) 1997 second quarter (97B), the acquisition computer triggered two hundred and forth-eight times. Of these triggers three were local earthquakes: one in the pre-basalt sediments, and two in the crystalline basement. The geologic and tectonic environments are discussed in the report

  15. First results of cross-correlation analysis of ambient seismic noise from the Hellenic Unified Seismic Network

    NARCIS (Netherlands)

    Panou, Areti; Paulssen, Hanneke; Hatzidimitriou, Panagiotis

    2015-01-01

    In this study we present phase velocity maps that were obtained from the cross-correlation analysis of ambient seismic noise recorded in the region of Greece.We used one year (2013) of ambient seismic data obtained from the vertical component of 64 broadband permanent seismological stations that are

  16. Observations and modeling of seismic background noise

    Science.gov (United States)

    Peterson, Jon R.

    1993-01-01

    The preparation of this report had two purposes. One was to present a catalog of seismic background noise spectra obtained from a worldwide network of seismograph stations. The other purpose was to refine and document models of seismic background noise that have been in use for several years. The second objective was, in fact, the principal reason that this study was initiated and influenced the procedures used in collecting and processing the data.With a single exception, all of the data used in this study were extracted from the digital data archive at the U.S. Geological Survey's Albuquerque Seismological Laboratory (ASL). This archive dates from 1972 when ASL first began deploying digital seismograph systems and collecting and distributing digital data under the sponsorship of the Defense Advanced Research Projects Agency (DARPA). There have been many changes and additions to the global seismograph networks during the past twenty years, but perhaps none as significant as the current deployment of very broadband seismographs by the U.S. Geological Survey (USGS) and the University of California San Diego (UCSD) under the scientific direction of the IRIS consortium. The new data acquisition systems have extended the bandwidth and resolution of seismic recording, and they utilize high-density recording media that permit the continuous recording of broadband data. The data improvements and continuous recording greatly benefit and simplify surveys of seismic background noise.Although there are many other sources of digital data, the ASL archive data were used almost exclusively because of accessibility and because the data systems and their calibration are well documented for the most part. Fortunately, the ASL archive contains high-quality data from other stations in addition to those deployed by the USGS. Included are data from UCSD IRIS/IDA stations, the Regional Seismic Test Network (RSTN) deployed by Sandia National Laboratories (SNL), and the TERRAscope network

  17. Single-station 6C beamforming

    Science.gov (United States)

    Nakata, N.; Hadziioannou, C.; Igel, H.

    2017-12-01

    Six-component measurements of seismic ground motion provide a unique opportunity to identify and decompose seismic wavefields into different wave types and incoming azimuths, as well as estimate structural information (e.g., phase velocity). By using the relationship between the transverse component and vertical rotational motion for Love waves, we can find the incident azimuth of the wave and the phase velocity. Therefore, when we scan the entire range of azimuth and slownesses, we can process the seismic waves in a similar way to conventional beamforming processing, without using a station array. To further improve the beam resolution, we use the distribution of amplitude ratio between translational and rotational motions at each time sample. With this beamforming, we decompose multiple incoming waves by azimuth and phase velocity using only one station. We demonstrate this technique using the data observed at Wettzell (vertical rotational motion and 3C translational motions). The beamforming results are encouraging to extract phase velocity at the location of the station, apply to oceanic microseism, and to identify complicated SH wave arrivals. We also discuss single-station beamforming using other components (vertical translational and horizontal rotational components). For future work, we need to understand the resolution limit of this technique, suitable length of time windows, and sensitivity to weak motion.

  18. Annual report on the KSRS seismic array operation

    Energy Technology Data Exchange (ETDEWEB)

    Jun, Myung-Soon; Jeon, Jeong-Soo; Kang, Ik-Bum [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

    1999-12-01

    Wonju KSRS (PS31) is one of the primary seismic stations under the IMS of CTBT. Korean NDC has been transmitting real time seismic data to IDC successfully during 1999. We have installed four elements seismo-acoustic array KISS(Korea Infrasound and Seismic Station) to detect and identify the seismic events in and around the Korean peninsula as a joint cooperation between KIGAM and SMU(Southern Methodist University). Continuous data from KSRS, KISS and other stations were automatically detected and analyzed using KEMS(Korea Earthquake Monitoring System) at KIGAM. KEMS has automatically detected and analyzed 1943 events between 1998.12.10 and 1999.12.22 and 876 events were reviewed by analyst and listed. Some electric poles used for data transmission inside the KSRS were eliminated and replaced to radio transmission. To increase the accuracy of earthquake observation velocity structure under the Korean peninsula was studied. To develop the Magnitude scale in Korea, the same approach which Richter applied in USA, 1935, was studied using Korean data. (author). 23 refs., 13 tabs., 89 figs.

  19. Seismic Tomography and the Development of a State Velocity Profile

    Science.gov (United States)

    Marsh, S. J.; Nakata, N.

    2017-12-01

    Earthquakes have been a growing concern in the State of Oklahoma in the last few years and as a result, accurate earthquake location is of utmost importance. This means using a high resolution velocity model with both lateral and vertical variations. Velocity data is determined using ambient noise seismic interferometry and tomography. Passive seismic data was acquired from multiple IRIS networks over the span of eight years (2009-2016) and filtered for earthquake removal to obtain the background ambient noise profile for the state. Seismic Interferometry is applied to simulate ray paths between stations, this is done with each possible station pair for highest resolution. Finally the method of seismic tomography is used to extract the velocity data and develop the state velocity map. The final velocity profile will be a compilation of different network analyses due to changing station availability from year to year. North-Central Oklahoma has a dense seismic network and has been operating for the past few years. The seismic stations are located here because this is the most seismically active region. Other parts of the state have not had consistent coverage from year to year, and as such a reliable and high resolution velocity profile cannot be determined from this network. However, the Transportable Array (TA) passed through Oklahoma in 2014 and provided a much wider and evenly spaced coverage. The goal of this study is to ultimately combine these two arrays over time, and provide a high quality velocity profile for the State of Oklahoma.

  20. Seismic Readings from the Deepest Borehole in the New Madrid Seismic Zone

    Energy Technology Data Exchange (ETDEWEB)

    Woolery, Edward W [KY Geological Survey, Univ of KY; Wang, Zhenming [KY Geological Survey, Univ of KY; Sturchio, Neil C [Dept of earth and Env. Sciences, Univ of Ill at Chicago

    2006-03-01

    Since the 1980s, the research associated with the UK network has been primarily strong-motion seismology of engineering interest. Currently the University of Kentucky operates a strong-motion network of nine stations in the New Madrid Seismic Zone. A unique feature of the network is the inclusions of vertical strong-motion arrays, each with one or two downhole accelerometers. The deepest borehole array is 260 m below the surfaces at station VASA in Fulton County, Kentucky. A preliminary surface seismic refraction survey was conducted at the site before drilling the hole at VSAS (Woolery and Wang, 2002). The depth to the Paleozoic bedrock at the site was estimated to be approximately 595 m, and the depth to the first very stiff layer (i.e. Porters Creek Clay) was found to be about 260 m. These depths and stratigraphic interpretation correlated well with a proprietary seismic reflection line and the Ken-Ten Oil Exploration No. 1 Sanger hole (Schwalb, 1969), as well as our experience in the area (Street et al., 1995; Woolery et al., 1999).

  1. The seismic monitoring network of Mt. Vesuvius

    Directory of Open Access Journals (Sweden)

    Massimo Orazi

    2013-11-01

    Full Text Available Mt. Vesuvius (southern Italy is one of the most hazardous volcanoes in the world. Its activity is currently characterized by moderate seismicity, with hypocenters located beneath the crater zone with depth rarely exceeding 5 km and magnitudes generally less than 3. The current configuration of the seismic monitoring network of Mt. Vesuvius consists of 18 seismic stations and 7 infrasound microphones. During the period 2006-2010 a seismic array with 48 channels was also operative. The station distribution provides appropriate coverage of the area around the volcanic edifice. The current development of the network and its geometry, under conditions of low seismic noise, allows locating seismic events with M<1. Remote instruments continuously transmit data to the main acquisition center in Naples. Data transmission is realized using different technological solutions based on UHF, Wi-Fi radio links, and TCP/IP client-server applications. Data are collected in the monitoring center of the Osservatorio Vesuviano (Italian National Institute of Geophysics and Volcanology, Naples section, which is equipped with systems for displaying and analyzing signals, using both real-time automatic and manual procedures. 24-hour surveillance allows to immediately communicate any significant anomaly to the Civil Protection authorities.

  2. Seismic activity in northeastern Brazill-new perspectives

    Science.gov (United States)

    Ferreira, J. M.; Do Nascimento, A. F.; Vilar, C. S.; Bezerra, F. H.; Assumpcao, M.; Berrocal, J.; Fuck, R. A.

    2007-05-01

    Northeastern Brazil is the most seismic active region in the country. Some earthquakes with magnitude above 5.0 and intensity VII MM associated with swam-like seismic activity lasting for many years are a serious social concern. Since the 1980's macroseismic and instrumental surveys have been carried out in this region and they are an important data archive which allows the composition of a reliable catalogue of seismic activity for this region. Among the many scientific results it was possible to identify the main seismogenic areas, obtain reliable hypocentres and focal mechanisms. As a consequence, it was possible also to analyse the relationship between seismicity and geological features. It was also possible to determined maximum horizontal stress direction for the region. An important induced seismic activity case has also been reported in the area as being a classical example of pore pressure diffusion triggering mechanism. The majority of the results were obtained using analogic data. Recently, a new research project is being conducted and will allow us to provide a regional scale monitoring with 6 broad-band stations and a new portable six station digital seismic network equipped with short- period sensors. Thus, with the continuous seismic activity in the area we trust that the results of this project will increase the present knowledge of seismic activity in northeastern Brazil.

  3. Hanford quarterly seismic report - 97C seismicity on and near the Hanford Site, Pasco Basin, Washington. Quarterly report, April 1, 1997--June 30, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Hartshorn, D.C.; Reidel, S.P.; Rohay, A.C.

    1997-08-01

    Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the U.S. Department of Energy and contractors. The staff also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for activities ranging from waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of an earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (EWRN) consist of 41 individual sensor sites and 15 radio relay sites maintained by the Seismic Monitoring staff. Most stations and five relay sites are solar powered. The operational rate for the second quarter of FY97 for stations in the HSN was 100% and for stations of the EWRN was 99.99%. For fiscal year (FY) 1997 third quarter (97C), the acquisition computer triggered 183. Of these triggers twenty one were local earthquakes: sixteen in the Columbus River Basalt Group, one in the pre-basalt sediments, and four in the crystalline basement. The geologic and tectonic environments are discussed in the report.

  4. Seismic Ecology

    Science.gov (United States)

    Seleznev, V. S.; Soloviev, V. M.; Emanov, A. F.

    The paper is devoted to researches of influence of seismic actions for industrial and civil buildings and people. The seismic actions bring influence directly on the people (vibration actions, force shocks at earthquakes) or indirectly through various build- ings and the constructions and can be strong (be felt by people) and weak (be fixed by sensing devices). The great number of work is devoted to influence of violent seismic actions (first of all of earthquakes) on people and various constructions. This work is devoted to study weak, but long seismic actions on various buildings and people. There is a need to take into account seismic oscillations, acting on the territory, at construction of various buildings on urbanized territories. Essential influence, except for violent earthquakes, man-caused seismic actions: the explosions, seismic noise, emitted by plant facilities and moving transport, radiation from high-rise buildings and constructions under action of a wind, etc. can exert. Materials on increase of man- caused seismicity in a number of regions in Russia, which earlier were not seismic, are presented in the paper. Along with maps of seismic microzoning maps to be built indicating a variation of amplitude spectra of seismic noise within day, months, years. The presence of an information about amplitudes and frequencies of oscillations from possible earthquakes and man-caused oscillations in concrete regions allows carry- ing out soundly designing and construction of industrial and civil housing projects. The construction of buildings even in not seismically dangerous regions, which have one from resonance frequencies coincident on magnitude to frequency of oscillations, emitted in this place by man-caused objects, can end in failure of these buildings and heaviest consequences for the people. The practical examples of detail of engineering- seismological investigation of large industrial and civil housing projects of Siberia territory (hydro power

  5. The Non-Proliferation Experiment recorded at the Pinedale Seismic Research Facility

    Energy Technology Data Exchange (ETDEWEB)

    Carr, D.B. [Sandia National Laboratories, Albuquerque, NM (United States)

    1994-12-31

    The Non-Proliferation Experiment was recorded by five different seismic stations operated by Sandia National Laboratories at the Pinedale Seismic Research Facility, approximately 7.6{degrees} from the Nevada Test Site. Two stations are different versions of the Deployable Seismic Verification System developed by the Department of Energy to provide seismic data to verify compliance with a Comprehensive Test Ban Treaty. Vault and borehole versions of the Designated Seismic Stations also recorded the event. The final station is test instrumentation located at depths of 10, 40 and 1200 feet. Although the event is seen clearly at all the stations, there are variations in the raw data due to the different bandwidths and depths of deployment. One Deployable Seismic Verification System has been operating at Pinedale for over three years and in that time recorded 14 nuclear explosions and 4 earthquakes from the Nevada Test Site, along with numerous other western U.S. earthquakes. Several discriminants based on the work by Taylor et al. (1989) have been applied to this data. First the discriminants were tested by comparing the explosions only to the 4 earthquakes located on the Test Site. Only one discriminant, log(L{sub g}/P{sub g}), did not show clear separation between the earthquakes and nuclear explosions. When other western U.S. events are included, only the M{sub b} vs. M{sub s} discriminant separated the event. In all cases where discrimination was possible, the Non-Proliferation Experiment was indistinguishable from a nuclear explosion.

  6. The Central and Eastern U.S. Seismic Network: Legacy of USArray

    Science.gov (United States)

    Eakins, J. A.; Astiz, L.; Benz, H.; Busby, R. W.; Hafner, K.; Reyes, J. C.; Sharer, G.; Vernon, F.; Woodward, R.

    2014-12-01

    As the USArray Transportable Array entered the central and eastern United States, several Federal agencies (National Science Foundation, U.S. Geological Survey, U.S. Nuclear Regulatory Commission, and Department of Energy) recognized the unique opportunity to retain TA stations beyond the original timeline. The mission of the CEUSN is to produce data that enables researchers and Federal agencies alike to better understand the basic geologic questions, background earthquake rates and distribution, seismic hazard potential, and associated societal risks of this region. The selected long-term sub-array from Transportable Array (TA) stations includes nearly 200 sites, complemented by 100 broadband stations from the existing regional seismic networks to form the Central and Eastern United States Network (CEUSN). Multiple criteria for site selection were weighed by an inter-agency TA Station Selection (TASS) Working Group: seismic noise characteristics, data availability in real time, proximity to nuclear power plants, and homogeneous distribution throughout the region. The Array Network Facility (ANF) started collecting data for CEUSN network stations since late 2013, with all stations collected since May 2014. Regional seismic data streams are collected in real-time from the IRIS Data Management Center (DMC). TA stations selected to be part of CEUSN, retain the broadband sensor to which a 100 sps channel is added, the infrasound and environmental channels, and, at some stations, accelerometers are deployed. The upgraded sites become part of the N4 network for which ANF provides metadata and can issue remote commands to the station equipment. Stations still operated by TA, but planned for CEUSN, are included in the virtual network so all stations are currently available now. By the end of 2015, the remaining TA stations will be upgraded. Data quality control procedures developed for TA stations at ANF and at the DMC are currently performed on N4 data. However

  7. Seismic risk assessment of a BWR

    International Nuclear Information System (INIS)

    Wells, J.E.; Bernreuter, D.L.; Chen, J.C.; Lappa, D.A.; Chuang, T.Y.; Murray, R.C.; Johnson, J.J.

    1987-01-01

    The simplified seismic risk methodology developed in the USNRC Seismic Safety Margins Research Program (SSMRP) was demonstrated by its application to the Zion nuclear power plant (PWR). The simplified seismic risk methodology was developed to reduce the costs associated with a seismic risk analysis while providing adequate results. A detailed model of Zion, including systems analysis models (initiating events, event trees, and fault trees), SSI and structure models, and piping models, was developed and used in assessing the seismic risk of the Zion nuclear power plant (FSAR). The simplified seismic risk methodology was applied to the LaSalle County Station nuclear power plant, a BWR; to further demonstrate its applicability, and if possible, to provide a basis for comparing the seismic risk from PWRs and BWRs. (orig./HP)

  8. Seismic and tsunami safety margin assessment

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-08-15

    Nuclear Regulation Authority is going to establish new seismic and tsunami safety guidelines to increase the safety of NPPs. The main purpose of this research is testing structures/components important to safety and tsunami resistant structures/components, and evaluating the capacity of them against earthquake and tsunami. Those capacity data will be utilized for the seismic and tsunami back-fit review based on the new seismic and tsunami safety guidelines. The summary of the program in 2012 is as follows. 1. Component seismic capacity test and quantitative seismic capacity evaluation. PWR emergency diesel generator partial-model seismic capacity tests have been conducted and quantitative seismic capacities have been evaluated. 2. Seismic capacity evaluation of switching-station electric equipment. Existing seismic test data investigation, specification survey and seismic response analyses have been conducted. 3. Tsunami capacity evaluation of anti-inundation measure facilities. Tsunami pressure test have been conducted utilizing a small breakwater model and evaluated basic characteristics of tsunami pressure against seawall structure. (author)

  9. Seismic and tsunami safety margin assessment

    International Nuclear Information System (INIS)

    2013-01-01

    Nuclear Regulation Authority is going to establish new seismic and tsunami safety guidelines to increase the safety of NPPs. The main purpose of this research is testing structures/components important to safety and tsunami resistant structures/components, and evaluating the capacity of them against earthquake and tsunami. Those capacity data will be utilized for the seismic and tsunami back-fit review based on the new seismic and tsunami safety guidelines. The summary of the program in 2012 is as follows. 1. Component seismic capacity test and quantitative seismic capacity evaluation. PWR emergency diesel generator partial-model seismic capacity tests have been conducted and quantitative seismic capacities have been evaluated. 2. Seismic capacity evaluation of switching-station electric equipment. Existing seismic test data investigation, specification survey and seismic response analyses have been conducted. 3. Tsunami capacity evaluation of anti-inundation measure facilities. Tsunami pressure test have been conducted utilizing a small breakwater model and evaluated basic characteristics of tsunami pressure against seawall structure. (author)

  10. Studies of infrasound propagation using the USArray seismic network (Invited)

    Science.gov (United States)

    Hedlin, M. A.; Degroot-Hedlin, C. D.; Walker, K. T.

    2010-12-01

    Although there are currently ~ 100 infrasound arrays worldwide, more than ever before, the station density is still insufficient to provide validation for detailed propagation modeling. Much structure in the atmosphere is short-lived and occurs at spatial scales much smaller than the average distance between infrasound stations. Relatively large infrasound signals can be observed on seismic channels due to coupling at the Earth's surface. Recent research, using data from the 70-km spaced 400-station USArray and other seismic network deployments, has shown the value of dense seismic network data for filling in the gaps between infrasound arrays. The dense sampling of the infrasound wavefield has allowed us to observe complete travel-time branches of infrasound signals and shed more light on the nature of infrasound propagation. We present early results from our studies of impulsive atmospheric sources, such as series of UTTR rocket motor detonations in Utah. The Utah blasts have been well recorded by USArray seismic stations and infrasound arrays in Nevada and Washington State. Recordings of seismic signals from a series of six events in 2007 are used to pinpoint the shot times to < 1 second. Variations in the acoustic branches and signal arrival times at the arrays are used to probe variations in atmospheric structure. Although we currently use coupled signals we anticipate studying dense acoustic network recordings as the USArray is currently being upgraded with infrasound microphones. These new sensors will allow us to make semi-continental scale network recordings of infrasound signals free of concerns about how the signals observed on seismic channels were modified when being coupled to seismic.

  11. Seismic verification of underground explosions

    International Nuclear Information System (INIS)

    Glenn, L.A.

    1986-01-01

    The principal tools for monitoring compliance with a comprehensive test ban treaty (CTBT), prohibiting all testing of nuclear weapons, are seismic networks and surveillance satellites. On-site inspections might also be required to resolve ambiguous events. The critical element of the monitoring system is the network of seismic stations, and in particular the in-country station. Internal stations provide much more useful data than do stations outside the borders of testing nations. For large events that are not eliminated by depth or location, one of the most useful discriminants is based on the ratio of surface-wave to body-wave magnitudes (M /sub s/ :m /sub b/ ). If an explosion and an earthquake have the same body-wave magnitude, the surface-wave magnitude for the earthquake is generally larger. It has yet to be proven that M /sub s/ :m /sub b/ is useful at low magnitudes, expecially when explosions are set off in long tunnels or odd-shaped cavities. A number of other promising regional discriminants have been suggested. Evasion opportunities and cavity decoupling are discussed

  12. An Analysis of Mechanical Constraints when Using Superconducting Gravimeters for Far-Field Pre-Seismic Anomaly Detection

    Directory of Open Access Journals (Sweden)

    Shyh-Chin Lan

    2011-01-01

    Full Text Available Pre-seismic gravity anomalies from records obtained at a 1 Hz sampling rate from superconducting gravimeters (SG around East Asia are analyzed. A comparison of gravity anomalies to the source parameters of associated earthquakes shows that the detection of pre-seismic gravity anomalies is constrained by several mechanical conditions of the seismic fault plane. The constraints of the far-field pre-seismic gravity amplitude perturbation were examined and the critical spatial relationship between the SG station and the epicenter precursory signal for detection was determined. The results show that: (1 the pre-seismic amplitude perturbation of gravity is inversely proportional to distance; (2 the transfer path from the epicenter to the SG station that crosses a tectonic boundary has a relatively low pre-seismic gravity anomaly amplitude; (3 the pre-seismic gravity perturbation amplitude is also affected by the attitude between the location of an SG station and the strike of the ruptured fault plane. The removal of typhoon effects and the selection of SG stations within a certain intersection angle to the strike of the fault plane are essential for obtaining reliable pre-seismic gravity anomaly results.

  13. New strong motion network in Georgia: basis for specifying seismic hazard

    Science.gov (United States)

    Kvavadze, N.; Tsereteli, N. S.

    2017-12-01

    Risk created by hazardous natural events is closely related to sustainable development of the society. Global observations have confirmed tendency of growing losses resulting from natural disasters, one of the most dangerous and destructive if which are earthquakes. Georgia is located in seismically active region. So, it is imperative to evaluate probabilistic seismic hazard and seismic risk with proper accuracy. National network of Georgia includes 35 station all of which are seismometers. There are significant gaps in strong motion recordings, which essential for seismic hazard assessment. To gather more accelerometer recordings, we have built a strong motion network distributed on the territory of Georgia. The network includes 6 stations for now, with Basalt 4x datalogger and strong motion sensor Episensor ES-T. For each site, Vs30 and soil resonance frequencies have been measured. Since all but one station (Tabakhmelam near Tbilisi), are located far from power and internet lines special system was created for instrument operation. Solar power is used to supply the system with electricity and GSM/LTE modems for internet access. VPN tunnel was set up using Raspberry pi, for two-way communication with stations. Tabakhmela station is located on grounds of Ionosphere Observatory, TSU and is used as a hub for the network. This location also includes a broadband seismometer and VLF electromagnetic waves observation antenna, for possible earthquake precursor studies. On server, located in Tabakhmela, the continues data is collected from all the stations, for later use. The recordings later will be used in different seismological and engineering problems, namely selecting and creating GMPE model for Caucasus, for probabilistic seismic hazard and seismic risk evaluation. These stations are a start and in the future expansion of strong motion network is planned. Along with this, electromagnetic wave observations will continue and additional antennas will be implemented

  14. Seismicity related to geothermal development in Dixie Valley, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Ryall, A.S.; Vetter, U.R.

    1982-07-08

    A ten-station seismic network was operated in and around the Dixie Valley area from January 1980 to November 1981; three of these stations are still in operation. Data from the Dixie Valley network were analyzed through 30 Jun 1981, and results of analysis were compared with analysis of somewhat larger events for the period 1970-1979. The seismic cycle in the Western Great Basic, the geologic structural setting, and the instrumentation are also described.

  15. Reflection imaging of the Moon's interior using deep-moonquake seismic interferometry

    Science.gov (United States)

    Nishitsuji, Yohei; Rowe, C. A.; Wapenaar, Kees; Draganov, Deyan

    2016-04-01

    The internal structure of the Moon has been investigated over many years using a variety of seismic methods, such as travel time analysis, receiver functions, and tomography. Here we propose to apply body-wave seismic interferometry to deep moonquakes in order to retrieve zero-offset reflection responses (and thus images) beneath the Apollo stations on the nearside of the Moon from virtual sources colocated with the stations. This method is called deep-moonquake seismic interferometry (DMSI). Our results show a laterally coherent acoustic boundary around 50 km depth beneath all four Apollo stations. We interpret this boundary as the lunar seismic Moho. This depth agrees with Japan Aerospace Exploration Agency's (JAXA) SELenological and Engineering Explorer (SELENE) result and previous travel time analysis at the Apollo 12/14 sites. The deeper part of the image we obtain from DMSI shows laterally incoherent structures. Such lateral inhomogeneity we interpret as representing a zone characterized by strong scattering and constant apparent seismic velocity at our resolution scale (0.2-2.0 Hz).

  16. ANZA Seismic Network- From Monitoring to Science

    Science.gov (United States)

    Vernon, F.; Eakin, J.; Martynov, V.; Newman, R.; Offield, G.; Hindley, A.; Astiz, L.

    2007-05-01

    The ANZA Seismic Network (http:eqinfo.ucsd.edu) utilizes broadband and strong motion sensors with 24-bit dataloggers combined with real-time telemetry to monitor local and regional seismicity in southernmost California. The ANZA network provides real-time data to the IRIS DMC, California Integrated Seismic Network (CISN), other regional networks, and the Advanced National Seismic System (ANSS), in addition to providing near real-time information and monitoring to the greater San Diego community. Twelve high dynamic range broadband and strong motion sensors adjacent to the San Jacinto Fault zone contribute data for earthquake source studies and continue the monitoring of the seismic activity of the San Jacinto fault initiated 24 years ago. Five additional stations are located in the San Diego region with one more station on San Clemente Island. The ANZA network uses the advance wireless networking capabilities of the NSF High Performance Wireless Research and Education Network (http:hpwren.ucsd.edu) to provide the communication infrastructure for the real-time telemetry of Anza seismic stations. The ANZA network uses the Antelope data acquisition software. The combination of high quality hardware, communications, and software allow for an annual network uptime in excess of 99.5% with a median annual station real-time data return rate of 99.3%. Approximately 90,000 events, dominantly local sources but including regional and teleseismic events, comprise the ANZA network waveform database. All waveform data and event data are managed using the Datascope relational database. The ANZA network data has been used in a variety of scientific research including detailed structure of the San Jacinto Fault Zone, earthquake source physics, spatial and temporal studies of aftershocks, array studies of teleseismic body waves, and array studies on the source of microseisms. To augment the location, detection, and high frequency observations of the seismic source spectrum from local

  17. Seismic monitoring at Deception Island volcano (Antarctica): the 2010-2011 survey

    Science.gov (United States)

    Martín, R.; Carmona, E.; Almendros, J.; Serrano, I.; Villaseñor, A.; Galeano, J.

    2012-04-01

    As an example of the recent advances introduced in seismic monitoring of Deception Island volcano (Antarctica) during recent years, we describe the instrumental network deployed during the 2010-2011 survey by the Instituto Andaluz de Geofísica of University of Granada, Spain (IAG-UGR). The period of operation extended from December 19, 2010 to March 5, 2011. We deployed a wireless seismic network composed by four three-component seismic stations. These stations are based on 24-bit SL04 SARA dataloggers sampling at 100 sps. They use a PC with embedded linux and SEISLOG data acquisition software. We use two types of three-component seismometers: short-period Mark L4C with natural frequency of 1 Hz and medium-period Lennartz3D/5s with natural frequency of 0.2 Hz. The network was designed for an optimum spatial coverage of the northern half of Deception, where a magma chamber has been reported. Station locations include the vicinity of the Spanish base "Gabriel de Castilla" (GdC), Obsidianas Beach, a zone near the craters from the 1970 eruptions, and the Chilean Shelter located south of Pendulum Cove. Continuous data from the local seismic network are received in real-time in the base by wifi transmission. We used Ubiquiti Networks Nanostation2 antennas with 2.4 GHz, dual-polarity, 10 dBi gain, and 54 Mbps transmission rate. They have shown a great robustness and speed for real-time applications. To prioritize data acquisition when the battery level is low, we have designed a circuit that allows independent power management for the seismic station and wireless transmission system. The reception antenna located at GdC is connected to a computer running SEISCOMP. This software supports several transmission protocols and manages the visualization and recording of seismic data, including the generation of summary plots to show the seismic activity. These twelve data channels are stored in miniseed format and displayed in real time, which allows for a rapid evaluation of

  18. Optimization of Broadband Seismic Network in the Kingdom of Saudi Arabia

    KAUST Repository

    Alshuhail, Abdulrahman

    2011-05-01

    Saudi Arabia covers a large portion of the Arabian plate, a region characterized by seismic activity, along complex divergent and convergent plate boundaries. In order to understand these plate boundaries it is essential to optimize the design of the broadband seismic station network to accurately locate earthquakes. In my study, I apply an optimization method to design the broadband station distribution in Saudi Arabia. This method is based on so called D-optimal planning criterion that optimizes the station distribution for locating the hypocenters of earthquakes. Two additional adjustments were implemented: to preferentially acquire direct and refracted wave, and to account for geometric spreading of seismic waves (and thus increases the signal to noise ratio). The method developed in this study for optimizing the geographical location of broadband stations uses the probability of earthquake occurrence and a 1-D velocity model of the region, and minimizes the ellipsoid volume of the earthquake location errors. The algorithm was applied to the current seismic network, operated by the Saudi Geologic Survey (SGS). Based on the results, I am able to make recommendations on, how to expand the existing network. Furthermore, I quantify the efficiency of our method by computing the standard error of epicenter and depth before and after adding the proposed stations.

  19. Amplification Factors for Spectral Acceleration Using Borehole Seismic Array in Taiwan

    Science.gov (United States)

    Lai, T. S.; Yih-Min, W.; Chao, W. A.; Chang, C. H.

    2017-12-01

    In order to reduce the noise from surface to get the high-quality seismic recordings, there are 54 borehole seismic arrays have been installed in Taiwan deployed by Central Weather Bureau (CWB) until the end of 2016. Each array includes two force balance accelerometers, one at the surface and other inside the borehole, as well as one broadband seismometer inside the borehole. The downhole instruments are placed at a depth between 120 and 400 m. The background noise level are lower at the borehole stations, but the amplitudes recorded by borehole stations are smaller than surface stations for the same earthquake due to the different geology conditions. Therefore, the earthquake magnitude estimated by borehole station is smaller than surface station. So far, CWB only use the surface stations in the magnitude determination due to this situation. In this study, we investigate the site effects between surface and downhole for borehole seismic arrays. Using the spectral ratio derived by the two-station spectral method as the transfer function, simulated the waveform recorded by borehole stations to the surface stations. In the future, through the transfer function, the borehole stations will be included in the estimation of earthquake magnitude and the results of amplification factors can provide the information of near-surface site effects for the ground motion simulation applications.

  20. WILBER and PyWEED: Event-based Seismic Data Request Tools

    Science.gov (United States)

    Falco, N.; Clark, A.; Trabant, C. M.

    2017-12-01

    WILBER and PyWEED are two user-friendly tools for requesting event-oriented seismic data. Both tools provide interactive maps and other controls for browsing and filtering event and station catalogs, and downloading data for selected event/station combinations, where the data window for each event/station pair may be defined relative to the arrival time of seismic waves from the event to that particular station. Both tools allow data to be previewed visually, and can download data in standard miniSEED, SAC, and other formats, complete with relevant metadata for performing instrument correction. WILBER is a web application requiring only a modern web browser. Once the user has selected an event, WILBER identifies all data available for that time period, and allows the user to select stations based on criteria such as the station's distance and orientation relative to the event. When the user has finalized their request, the data is collected and packaged on the IRIS server, and when it is ready the user is sent a link to download. PyWEED is a downloadable, cross-platform (Macintosh / Windows / Linux) application written in Python. PyWEED allows a user to select multiple events and stations, and will download data for each event/station combination selected. PyWEED is built around the ObsPy seismic toolkit, and allows direct interaction and control of the application through a Python interactive console.

  1. The data quality analyzer: a quality control program for seismic data

    Science.gov (United States)

    Ringler, Adam; Hagerty, M.T.; Holland, James F.; Gonzales, A.; Gee, Lind S.; Edwards, J.D.; Wilson, David; Baker, Adam

    2015-01-01

    The U.S. Geological Survey's Albuquerque Seismological Laboratory (ASL) has several initiatives underway to enhance and track the quality of data produced from ASL seismic stations and to improve communication about data problems to the user community. The Data Quality Analyzer (DQA) is one such development and is designed to characterize seismic station data quality in a quantitative and automated manner.

  2. Processing of seismic signals from a seismometer network

    International Nuclear Information System (INIS)

    Key, F.A.; Warburton, P.J.

    1983-08-01

    A description is given of the Seismometer Network Analysis Computer (SNAC) which processes short period data from a network of seismometers (UKNET). The nine stations of the network are distributed throughout the UK and their outputs are transmitted to a control laboratory (Blacknest) where SNAC monitors the data for seismic signals. The computer gives an estimate of the source location of the detected signals and stores the waveforms. The detection logic is designed to maintain high sensitivity without excessive ''false alarms''. It is demonstrated that the system is able to detect seismic signals at an amplitude level consistent with a network of single stations and, within the limitations of signal onset time measurements made by machine, can locate the source of the seismic disturbance. (author)

  3. Adding seismic broadband analysis to characterize Andean backarc seismicity in Argentina

    Science.gov (United States)

    Alvarado, P.; Giuliano, A.; Beck, S.; Zandt, G.

    2007-05-01

    Characterization of the highly seismically active Andean backarc is crucial for assessment of earthquake hazards in western Argentina. Moderate-to-large crustal earthquakes have caused several deaths, damage and drastic economic consequences in Argentinean history. We have studied the Andean backarc crust between 30°S and 36°S using seismic broadband data available from a previous ("the CHARGE") IRIS-PASSCAL experiment. We collected more than 12 terabytes of continuous seismic data from 22 broadband instruments deployed across Chile and Argentina during 1.5 years. Using free software we modeled full regional broadband waveforms and obtained seismic moment tensor inversions of crustal earthquakes testing for the best focal depth for each event. We also mapped differences in the Andean backarc crustal structure and found a clear correlation with different types of crustal seismicity (i.e. focal depths, focal mechanisms, magnitudes and frequencies of occurrence) and previously mapped terrane boundaries. We now plan to use the same methodology to study other regions in Argentina using near-real time broadband data available from the national seismic (INPRES) network and global seismic networks operating in the region. We will re-design the national seismic network to optimize short-period and broadband seismic station coverage for different network purposes. This work is an international effort that involves researchers and students from universities and national government agencies with the goal of providing more information about earthquake hazards in western Argentina.

  4. SEISMIC STUDY OF THE AGUA DE PAU GEOTHERMAL PROSPECT, SAO MIGUEL, AZORES.

    Science.gov (United States)

    Dawson, Phillip B.; Rodrigues da Silva, Antonio; Iyer, H.M.; Evans, John R.

    1985-01-01

    A 16 station array was operated over the 200 km**2 central portion of Sao Miguel utilizing 8 permanent Instituto Nacional de Meterologia e Geofisica stations and 8 USGS portable stations. Forty four local events with well constrained solutions and 15 regional events were located. In addition, hundreds of unlocatable seismic events were recorded. The most interesting seismic activity occurred in a swarm on September 6 and 7, 1983 when over 200 events were recorded in a 16 hour period. The seismic activity around Agua de Pau was centered on the east and northeast slopes of the volcano. The data suggest a boiling hydrothermal system beneath the Agua de Pau volcano, consistent with a variety of other data.

  5. Correlation Between Electromagnetic Signals and Seismic Events on Central Colombia Region to Establish Seismic Precursors Existence

    Science.gov (United States)

    Caneva, A.; Vargas Jiménez, C. A.; Solano Fino, J. M.

    2017-12-01

    It was already shown by several authors around the world some kinds of correlation between electric and magnetic signals and seismic events looking for precursors to the last ones emitted from the seismic source. This investigation tends to establish a correlation between electro-magnetic (EM) signals on the ground surface and seismic events on the Colombian lithospheric system. The events correlation was made with data from the Seismological Network of the Sabana de Bogotá (RSSB for its acronym in Spanish), a temporal seismological network on Chichimene (Acacías, Meta, Colombia) and the National Seismological Network of Colombia (RSNC, for its acronym in Spanish). The project involved the design, construction and preliminary tests for the necessary instruments added to the RSSB as multi-parameter stations with seismic broadband, electric polarizing and non-polarizing dipoles and Earth's magnetic field sensors. Correlations were made considering time, frequency and `natural time' domains with filtering and preprocessing algorithms. Among the main results are the almost complete lack of electric disturbances known as Seismic Electric Signals (SES) and very few of the magnetic kind. However, another kind of long period magnetic disturbances for some stations and events where found. More instruments have to be deployed in order to get a better understanding of these disturbances and develop a robust model.

  6. Regional travel-time residual studies and station correction from 1-D velocity models for some stations around Peninsular Malaysia and Singapore

    Science.gov (United States)

    Osagie, Abel U.; Nawawi, Mohd.; Khalil, Amin Esmail; Abdullah, Khiruddin

    2017-06-01

    We have investigated the average P-wave travel-time residuals for some stations around Southern Thailand, Peninsular Malaysia and Singapore at regional distances. Six years (January, 2010-December, 2015) record of events from central and northern Sumatra was obtained from the digital seismic archives of Integrated Research Institute for Seismology (IRIS). The criteria used for the data selection are designed to be above the magnitude of mb 4.5, depth less than 200 km and an epicentral distance shorter than 1000 km. Within this window a total number of 152 earthquakes were obtained. Furthermore, data were filtered based on the clarity of the seismic phases that are manually picked. A total of 1088 P-wave arrivals and 962 S-wave arrivals were hand-picked from 10 seismic stations around the Peninsula. Three stations IPM, KUM, and KOM from Peninsular Malaysia, four stations BTDF, NTU, BESC and KAPK from Singapore and three stations SURA, SRIT and SKLT located in the southern part of Thailand are used. Station NTU was chosen as the Ref. station because it recorded the large number of events. Travel-times were calculated using three 1-D models (Preliminary Ref. Earth Model PREM (Dziewonski and Anderson, 1981, IASP91, and Lienert et al., 1986) and an adopted two-point ray tracing algorithm. For the three models, we corroborate our calculated travel-times with the results from the use of TAUP travel-time calculation software. Relative to station NTU, our results show that the average P wave travel-time residual for PREM model ranges from -0.16 to 0.45 s for BESC and IPM respectively. For IASP91 model, the average residual ranges from -0.25 to 0.24 s for SRIT and SKLT respectively, and ranges from -0.22 to 0.30 s for KAPK and IPM respectively for Lienert et al. (1986) model. Generally, most stations have slightly positive residuals relative to station NTU. These corrections reflect the difference between actual and estimated model velocities along ray paths to stations and

  7. The persistent signature of tropical cyclones in ambient seismic noise

    KAUST Repository

    Gualtieri, Lucia; Camargo, Suzana J.; Pascale, Salvatore; Pons, Flavio M.E.; Ekströ m, Gö ran

    2017-01-01

    The spectrum of ambient seismic noise shows strong signals associated with tropical cyclones, yet a detailed understanding of these signals and the relationship between them and the storms is currently lacking. Through the analysis of more than a decade of seismic data recorded at several stations located in and adjacent to the northwest Pacific Ocean, here we show that there is a persistent and frequency-dependent signature of tropical cyclones in ambient seismic noise that depends on characteristics of the storm and on the detailed location of the station relative to the storm. An adaptive statistical model shows that the spectral amplitude of ambient seismic noise, and notably of the short-period secondary microseisms, has a strong relationship with tropical cyclone intensity and can be employed to extract information on the tropical cyclones.

  8. The persistent signature of tropical cyclones in ambient seismic noise

    KAUST Repository

    Gualtieri, Lucia

    2017-12-28

    The spectrum of ambient seismic noise shows strong signals associated with tropical cyclones, yet a detailed understanding of these signals and the relationship between them and the storms is currently lacking. Through the analysis of more than a decade of seismic data recorded at several stations located in and adjacent to the northwest Pacific Ocean, here we show that there is a persistent and frequency-dependent signature of tropical cyclones in ambient seismic noise that depends on characteristics of the storm and on the detailed location of the station relative to the storm. An adaptive statistical model shows that the spectral amplitude of ambient seismic noise, and notably of the short-period secondary microseisms, has a strong relationship with tropical cyclone intensity and can be employed to extract information on the tropical cyclones.

  9. An Experimental Seismic Data and Parameter Exchange System for Interim NEAMTWS

    Science.gov (United States)

    Hanka, W.; Hoffmann, T.; Weber, B.; Heinloo, A.; Hoffmann, M.; Müller-Wrana, T.; Saul, J.

    2009-04-01

    In 2008 GFZ Potsdam has started to operate its global earthquake monitoring system as an experimental seismic background data centre for the interim NEAMTWS (NE Atlantic and Mediterranean Tsunami Warning System). The SeisComP3 (SC3) software, developed within the GITEWS (German Indian Ocean Tsunami Early Warning System) project was extended to test the export and import of individual processing results within a cluster of SC3 systems. The initiated NEAMTWS SC3 cluster consists presently of the 24/7 seismic services at IMP, IGN, LDG/EMSC and KOERI, whereas INGV and NOA are still pending. The GFZ virtual real-time seismic network (GEOFON Extended Virtual Network - GEVN) was substantially extended by many stations from Western European countries optimizing the station distribution for NEAMTWS purposes. To amend the public seismic network (VEBSN - Virtual European Broadband Seismic Network) some attached centres provided additional private stations for NEAMTWS usage. In parallel to the data collection by Internet the GFZ VSAT hub for the secured data collection of the EuroMED GEOFON and NEAMTWS backbone network stations became operational and the first data links were established. In 2008 the experimental system could already prove its performance since a number of relevant earthquakes have happened in NEAMTWS area. The results are very promising in terms of speed as the automatic alerts (reliable solutions based on a minimum of 25 stations and disseminated by emails and SMS) were issued between 2 1/2 and 4 minutes for Greece and 5 minutes for Iceland. They are also promising in terms of accuracy since epicenter coordinates, depth and magnitude estimates were sufficiently accurate from the very beginning, usually don't differ substantially from the final solutions and provide a good starting point for the operations of the interim NEAMTWS. However, although an automatic seismic system is a good first step, 24/7 manned RTWCs are mandatory for regular manual verification

  10. Modernization of the Caltech/USGS Southern California Seismic Network

    Science.gov (United States)

    Bhadha, R.; Devora, A.; Hauksson, E.; Johnson, D.; Thomas, V.; Watkins, M.; Yip, R.; Yu, E.; Given, D.; Cone, G.; Koesterer, C.

    2009-12-01

    The USGS/ANSS/ARRA program is providing Government Furnished Equipment (GFE), and two year funding for upgrading the Caltech/USGS Southern California Seismic Network (SCSN). The SCSN is the modern digital ground motion seismic network in southern California that monitors seismicity and provides real-time earthquake information products such as rapid notifications, moment tensors, and ShakeMap. The SCSN has evolved through the years and now consists of several well-integrated components such as Short-Period analog, TERRAscope, digital stations, and real-time strong motion stations, or about 300 stations. In addition, the SCSN records data from about 100 stations provided by partner networks. To strengthen the ability of SCSN to meet the ANSS performance standards, we will install GFE and carry out the following upgrades and improvements of the various components of the SCSN: 1) Upgrade of dataloggers at seven TERRAscope stations; 2) Upgrade of dataloggers at 131 digital stations and upgrade broadband sensors at 25 stations; 3) Upgrade of SCSN metadata capabilities; 4) Upgrade of telemetry capabilities for both seismic and GPS data; and 5) Upgrade balers at stations with existing Q330 dataloggers. These upgrades will enable the SCSN to meet the ANSS Performance Standards more consistently than before. The new equipment will improve station uptimes and reduce maintenance costs. The new equipment will also provide improved waveform data quality and consequently superior data products. The data gaps due to various outages will be minimized, and ‘late’ data will be readily available through retrieval from on-site storage. Compared to the outdated equipment, the new equipment will speed up data delivery by about 10 sec, which is fast enough for earthquake early warning applications. The new equipment also has about a factor of ten lower consumption of power. We will also upgrade the SCSN data acquisition and data center facilities, which will improve the SCSN

  11. A new dataset of Wood Anderson magnitude from the Trieste (Italy) seismic station

    Science.gov (United States)

    Sandron, Denis; Gentile, G. Francesco; Gentili, Stefania; Rebez, Alessandro; Santulin, Marco; Slejko, Dario

    2014-05-01

    The standard torsion Wood Anderson (WA) seismograph owes its fame to the fact that historically it has been used for the definition of the magnitude of an earthquake (Richter, 1935). With the progress of the technology, digital broadband (BB) seismographs replaced it. However, for historical consistency and homogeneity with the old seismic catalogues, it is still important continuing to compute the so called Wood Anderson magnitude. In order to evaluate WA magnitude, the synthetic seismograms WA equivalent are simulated convolving the waveforms recorded by a BB instrument with a suitable transfer function. The value of static magnification that should be applied in order to simulate correctly the WA instrument is debated. The original WA instrument in Trieste operated from 1971 to 1992 and the WA magnitude (MAW) estimates were regularly reported in the seismic station bulletins. The calculation of the local magnitude was performed following the Richter's formula (Richter, 1935), using the table of corrections factor unmodified from those calibrated for California and without station correction applied (Finetti, 1972). However, the WA amplitudes were computed as vector sum rather than arithmetic average of the horizontal components, resulting in a systematic overestimation of approximately 0.25, depending on the azimuth. In this work, we have retrieved the E-W and N-S components of the original recordings and re-computed MAW according to the original Richter (1935) formula. In 1992, the WA recording were stopped, due to the long time required for the daily development of the photographic paper, the costs of the photographic paper and the progress of the technology. After a decade of interruption, the WA was recovered and modernized by replacing the recording on photographic paper with an electronic device and it continues presently to record earthquakes. The E-W and N-S components records were memorized, but not published till now. Since 2004, next to the WA (few

  12. Seismic stress of plants and equipment in nuclear power station construction

    International Nuclear Information System (INIS)

    Hampe, E.; Schwarz, J.

    1984-01-01

    The applicability of floor spectra for designing components of nuclear power plants taking into account seismic effects is discussed. Methods for the determination of seismic floor excitation and various kinds of floor spectra are presented. As an example the floor spectra method is applied to containment buildings

  13. Properties of Repetitive Long-Period Seismicity at Villarrica Volcano, Chile

    Science.gov (United States)

    Richardson, J.; Waite, G. P.; Palma, J.; Johnson, J. B.

    2011-12-01

    Villarrica Volcano, Chile hosts a persistent lava lake and is characterized by degassing and long-period seismicity. In order to better understand the relationship between outgassing and seismicity, we recorded broadband seismic and acoustic data along with high-rate SO2 emission data. We used both a densely-spaced linear array deployed on the northern flank of Villarrica, during the austral summer of 2011, and a wider aperture array of stations distributed around the volcano that was active in the austral summer of 2010. Both deployments consisted of three-component broadband stations and were augmented with broadband infrasound sensors. Of particular interests are repetitive, ~1 Hz seismic and coincident infrasound signals that occurred approximately every 2 minutes. Because these events are typically very low amplitude, we used a matched filter approach to identify them. We windowed several high-amplitude records of these events from broadband seismic stations near the vent. The record section of each event served as a template to compare with the entire dataset by cross-correlation. This approach identified ~20,000 nearly identical events during the ~7 day deployment of the linear array, which were otherwise difficult to identify in the raw records. Assuming that all of the events that we identified have identical source mechanisms and depths, we stack the large suite of events to produce low-noise records and particle motions at receivers farther than 5 km from the vent. We find that the records from stations near the edifice are dominated by tangential particle motion, suggesting the influence of near-field components. Correlation of these data with broadband acoustic data collected at the summit suggest that these repeatable seismic processes are linked to acoustic emissions, probably due to gas bubbles bursting at the magma free surface, as no eruptive products besides gas were being emitted by the volcano during the instrument deployment. The acoustic

  14. Hanford annual second quarter seismic report, fiscal year 1998: Seismicity on and near the Hanford Site, Pasco, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Hartshorn, D.C.; Reidel, S.P.; Rohay, A.C.

    1998-06-01

    Hanford Seismic Monitoring provides an uninterrupted collection of high quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the US Department of Energy and its contractors. The staff also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of an earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (ENN) consist of 42 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. The operational rate for the second quarter of FY98 for stations in the HSN was 99.92%. The operational rate for the second quarter of FY98 for stations of the EWRN was 99.46%. For the second quarter of FY98, the acquisition computer triggered 159 times. Of these triggers 14 were local earthquakes: 7 (50%) in the Columbia River Basalt Group, 3 (21%) in the pre-basalt sediments, and 4 (29%) in the crystalline basement. The geologic and tectonic environments where these earthquakes occurred are discussed in this report. The most significant seismic event for the second quarter was on March 23, 1998 when a 1.9 Mc occurred near Eltopia, WA and was felt by local residents. Although this was a small event, it was felt at the surface and is an indication of the potential impact on Hanford of seismic events that are common to the Site.

  15. Correction of clock errors in seismic data using noise cross-correlations

    Science.gov (United States)

    Hable, Sarah; Sigloch, Karin; Barruol, Guilhem; Hadziioannou, Céline

    2017-04-01

    Correct and verifiable timing of seismic records is crucial for most seismological applications. For seismic land stations, frequent synchronization of the internal station clock with a GPS signal should ensure accurate timing, but loss of GPS synchronization is a common occurrence, especially for remote, temporary stations. In such cases, retrieval of clock timing has been a long-standing problem. The same timing problem applies to Ocean Bottom Seismometers (OBS), where no GPS signal can be received during deployment and only two GPS synchronizations can be attempted upon deployment and recovery. If successful, a skew correction is usually applied, where the final timing deviation is interpolated linearly across the entire operation period. If GPS synchronization upon recovery fails, then even this simple and unverified, first-order correction is not possible. In recent years, the usage of cross-correlation functions (CCFs) of ambient seismic noise has been demonstrated as a clock-correction method for certain network geometries. We demonstrate the great potential of this technique for island stations and OBS that were installed in the course of the Réunion Hotspot and Upper Mantle - Réunions Unterer Mantel (RHUM-RUM) project in the western Indian Ocean. Four stations on the island La Réunion were affected by clock errors of up to several minutes due to a missing GPS signal. CCFs are calculated for each day and compared with a reference cross-correlation function (RCF), which is usually the average of all CCFs. The clock error of each day is then determined from the measured shift between the daily CCFs and the RCF. To improve the accuracy of the method, CCFs are computed for several land stations and all three seismic components. Averaging over these station pairs and their 9 component pairs reduces the standard deviation of the clock errors by a factor of 4 (from 80 ms to 20 ms). This procedure permits a continuous monitoring of clock errors where small clock

  16. Peru Subduction Zone Seismic Experiment (PeruSZE): Preliminary Results From a Seismic Network Between Mollendo and Lake Titicaca, Peru.

    Science.gov (United States)

    Guy, R.; Stubailo, I.; Skinner, S.; Phillips, K.; Foote, E.; Lukac, M.; Aguilar, V.; Tavera, H.; Audin, L.; Husker, A.; Clayton, R.; Davis, P. M.

    2008-12-01

    This work describes preliminary results from a 50 station broadband seismic network recently installed from the coast to the high Andes in Peru. UCLA's Center for Embedded Network Sensing (CENS) and Caltech's Tectonic Observatory are collaborating with the IRD (French L'Institut de Recherche pour le Developpement) and the Institute of Geophysics, in Lima Peru in a broadband seismic experiment that will study the transition from steep to shallow slab subduction. The currently installed line has stations located above the steep subduction zone at a spacing of about 6 km. In 2009 we plan to install a line of 50 stations north from this line along the crest of the Andes, crossing the transition from steep to shallow subduction. A further line from the end of that line back to the coast, completing a U shaped array, is in the planning phase. The network is wirelessly linked using multi-hop network software designed by computer scientists in CENS in which data is transmitted from station to station, and collected at Internet drops, from where it is transmitted over the Internet to CENS each night. The instrument installation in Peru is almost finished and we have been receiving data daily from 10 stations (out of total 50) since June 2008. The rest are recording on-site while the RF network is being completed. The software system provides dynamic link quality based routing, reliable data delivery, and a disruption tolerant shell interface for managing the system from UCLA without the need to travel to Peru. The near real-time data delivery also allows immediate detection of any problems at the sites. We are building a seismic data and GPS quality control toolset that would greatly minimize the station's downtime by alerting the users of any possible problems.

  17. Probing the internal structure of the asteriod Didymoon with a passive seismic investigation

    Science.gov (United States)

    Murdoch, N.; Hempel, S.; Pou, L.; Cadu, A.; Garcia, R. F.; Mimoun, D.; Margerin, L.; Karatekin, O.

    2017-09-01

    Understanding the internal structure of an asteroid has important implications for interpreting its evolutionary history, for understanding its continuing geological evolution, and also for asteroid deflection and in-situ space resource utilisation. Given the strong evidence that asteroids are seismically active, an in-situ passive seismic experiment could provide information about the asteroid surface and interior properties. Here, we discuss the natural seismic activity that may be present on Didymoon, the secondary component of asteroid (65803) Didymos. Our analysis of the tidal stresses in Didymoon shows that tidal quakes are likely to occur if the secondary has an eccentric orbit. Failure occurs most easily at the asteroid poles and close to the surface for both homogeneous and layered internal structures. Simulations of seismic wave propagation in Didymoon show that the seismic moment of even small meteoroid impacts can generate clearly observable body and surface waves if the asteroid's internal structure is homogeneous. The presence of a regolith layer over a consolidated core can result in the seismic energy becoming trapped in the regolith due to the strong impedance contrast at the regolith-core boundary. The inclusion of macro-porosity (voids) further complexifies the wavefield due to increased scattering. The most prominent seismic waves are always found to be those traveling along the surface of the asteroid and those focusing in the antipodal point of the seismic source. We find also that the waveforms and ground acceleration spectra allow discrimination between the different internal structure models. Although the science return of a passive seismic experiment would be enhanced by having multiple seismic stations, one single seismic station can already vastly improve our knowledge about the seismic environment and sub-surface structure of an asteroid. We describe several seismic measurement techniques that could be applied in order to study the

  18. Epicenter Location of Regional Seismic Events Using Love Wave and Rayleigh Wave Ambient Seismic Noise Green's Functions

    Science.gov (United States)

    Levshin, A. L.; Barmin, M. P.; Moschetti, M. P.; Mendoza, C.; Ritzwoller, M. H.

    2011-12-01

    We describe a novel method to locate regional seismic events based on exploiting Empirical Green's Functions (EGF) that are produced from ambient seismic noise. Elastic EGFs between pairs of seismic stations are determined by cross-correlating long time-series of ambient noise recorded at the two stations. The EGFs principally contain Rayleigh waves on the vertical-vertical cross-correlations and Love waves on the transverse-transverse cross-correlations. Earlier work (Barmin et al., "Epicentral location based on Rayleigh wave empirical Green's functions from ambient seismic noise", Geophys. J. Int., 2011) showed that group time delays observed on Rayleigh wave EGFs can be exploited to locate to within about 1 km moderate sized earthquakes using USArray Transportable Array (TA) stations. The principal advantage of the method is that the ambient noise EGFs are affected by lateral variations in structure similarly to the earthquake signals, so the location is largely unbiased by 3-D structure. However, locations based on Rayleigh waves alone may be biased by more than 1 km if the earthquake depth is unknown but lies between 2 km and 7 km. This presentation is motivated by the fact that group time delays for Love waves are much less affected by earthquake depth than Rayleigh waves; thus exploitation of Love wave EGFs may reduce location bias caused by uncertainty in event depth. The advantage of Love waves to locate seismic events, however, is mitigated by the fact that Love wave EGFs have a smaller SNR than Rayleigh waves. Here, we test the use of Love and Rayleigh wave EGFs between 5- and 15-sec period to locate seismic events based on the USArray TA in the western US. We focus on locating aftershocks of the 2008 M 6.0 Wells earthquake, mining blasts in Wyoming and Montana, and small earthquakes near Norman, OK and Dallas, TX, some of which may be triggered by hydrofracking or injection wells.

  19. Seismic and hydroacoustic analysis relevant to MH370

    Energy Technology Data Exchange (ETDEWEB)

    Stead, Richard J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-03

    The vicinity of the Indian Ocean is searched for open and readily available seismic and/or hydroacoustic stations that might have recorded a possible impact of MH370 with the ocean surface. Only three stations are identified: the IMS hydrophone arrays H01 and H08, and the Geoscope seismic station AIS. Analysis of the data from these stations shows an interesting arrival on H01 that has some interference from an Antarctic ice event, large amplitude repeating signals at H08 that obscure any possible arrivals, and large amplitude chaotic noise at AIS precludes any analysis at higher frequencies of interest. The results are therefore rather inconclusive but may point to a more southerly impact location within the overall Indian Ocean search region. The results would be more useful if they can be combined with any other data that are not readily available.

  20. Using VS30 to Estimate Station ML Adjustments (dML)

    Science.gov (United States)

    Yong, A.; Herrick, J.; Cochran, E. S.; Andrews, J. R.; Yu, E.

    2017-12-01

    Currently, new seismic stations added to a regional seismic network cannot be used to calculate local or Richter magnitude (ML) until a revised region-wide amplitude decay function is developed. The new station must record a minimum number of local and regional events that meet specific amplitude requirements prior to re-calibration of the amplitude decay function. Therefore, there can be significant delay between when a new station starts contributing real-time waveform packets and when the data can be included in magnitude estimation. The station component adjustments (dML; Uhrhammer et al., 2011) are calculated after first inverting for a new regional amplitude decay function, constrained by the sum of dML for long-running stations. Here, we propose a method to calculate an initial dML using known or proxy values of seismic site conditions. For site conditions, we use the time-averaged shear-wave velocity (VS) of the upper 30 m (VS30). We solve for dML as described in Equation (1) by Uhrhammer et al. (2011): ML = log (A) - log A0 (r) + dML, where A is the maximum Wood and Anderson (1925) trace amplitude (mm), r is the distance (km), and dML is the station adjustment. Measured VS30 and estimated dML data are comprised of records from 887 horizontal components (east-west and north-south orientations) from 93 seismic monitoring stations in the California Integrated Seismic Network. VS30 values range from 202 m/s to 1464 m/s and dML range from -1.10 to 0.39. VS30 and dML exhibit a positive correlation coefficient (R = 0.72), indicating that as VS30 increases, dML increases. This implies that greater site amplification (i.e., lower VS30) results in smaller ML. When we restrict VS30 regional network ML estimates immediately without the need to wait until a minimum set of earthquake data has been recorded.

  1. Crustal Deformation around Zhangjiakou-Bohai Seismically Active Belt

    Science.gov (United States)

    Jin, H.; Fu, G.; Kato, T.

    2011-12-01

    Zhangjiakou-Bohai belt is a seismically active belt located in Northern China around Beijing, the capital of China. Near such a belt many great earthquakes occurred in the past centuries (e.g. the 1976 Tanshan Ms7.8 earthquake, the 1998 Zhangbei Ms6.2 earthquake, etc). Chinese Government established dense permanent and regional Global Positioning System (GPS) stations in and near the area. We collected and analyzed all the GPS observation data between 1999 and 2009 around Zhangjiakou-Bohai seismic belt, and obtained velocities at 143 stations. At the same time we investigated Zhangjiakou-Bohai belt slip rate for three profiles from northwest to southeast, and constructed a regional strain field on the Zhangjiakou-Bohai seismic belt region by least-square collocation. Based on the study we found that: 1) Nowadays the Zhangjiakou-Bohai seismic belt is creeping with left-lateral slip rate of 2.0mm~2.4mm/a, with coupling depth of 35~50km; 2) In total, the slip and coupling depth of the northwestern seismic belt is less than the one of southeast side; 3) The maximum shear strain is about 3×10-8 at Beijing-Tianjin-Tangshan area.

  2. Propagation of Regional Seismic Phases in Western Europe

    Science.gov (United States)

    1991-03-08

    and Southeastern France recorded at short period stations of the LDG (Laboratoire de Detection Geophysique , France) and IGG (Istituto Geofisico di...here were provided by the L.D.G. (Laboratoire de Geophysique ). The french seismic network consists of 27 stations with the same features : the

  3. Pickering seismic safety margin

    International Nuclear Information System (INIS)

    Ghobarah, A.; Heidebrecht, A.C.; Tso, W.K.

    1992-06-01

    A study was conducted to recommend a methodology for the seismic safety margin review of existing Canadian CANDU nuclear generating stations such as Pickering A. The purpose of the seismic safety margin review is to determine whether the nuclear plant has sufficient seismic safety margin over its design basis to assure plant safety. In this review process, it is possible to identify the weak links which might limit the seismic performance of critical structures, systems and components. The proposed methodology is a modification the EPRI (Electric Power Research Institute) approach. The methodology includes: the characterization of the site margin earthquake, the definition of the performance criteria for the elements of a success path, and the determination of the seismic withstand capacity. It is proposed that the margin earthquake be established on the basis of using historical records and the regional seismo-tectonic and site specific evaluations. The ability of the components and systems to withstand the margin earthquake is determined by database comparisons, inspection, analysis or testing. An implementation plan for the application of the methodology to the Pickering A NGS is prepared

  4. Installation of a very broad band borehole seismic station in Ferrara (Emilia)

    OpenAIRE

    Pesaresi, Damiano; Dall'Olio, Lorella; Rovelli, Antonio; Romanelli, Marco; Barnaba, Carla; Abu Zeid, Nasser

    2012-01-01

    The Istituto Nazionale di Geofisica e Vulcanologia (INGV) is the Italian agency devoted to monitor in real time the seismicity on the Italian territory. The seismicity in Italy is of course variable in time and space, being also very much dependant on local noise conditions. Specifically, monitoring seismicity in an alluvial basin like the Po one is a challenge, due to consistent site effects induced by soft alluvial deposits and bad coupling with the deep bedrock (Steidl et al., 1996). This...

  5. Detection of cracks with low vertical offset in clayey formations from galleries by using seismic methods. Tournemire experimental station. First part: problem analysis and measurement sizing

    International Nuclear Information System (INIS)

    Bretaudeau, Francois; Gelis, Celine; Cabrera, Justo; Leparoux, Donatienne; Cote, Philippe

    2012-01-01

    Within the frame of the expertise of the ANDRA file on the project of storage of radioactive wastes in clayey formations, the detection of natural cracks which could locally alter the argillite containment properties is a crucial issue. As some previous studies showed that some cracks exhibiting a low vertical offset could not be detected in clayey formations from the surface, this document reports a study which aimed at assessing the possibility of detection of such a crack by means of seismic methods directly implemented from underground works. It reports a detailed analysis of the seismic imagery problem, the characterization of different areas of the investigated environment, the assessment and validation of various hypotheses by using experimental data obtained in an experimental station and numerical simulations. The potential of each envisaged method (migration, tomography, wave form inversion) is assessed, notably with respect to synthetic seismic data obtained by numerical modelling. Preliminary results are used to size a complete seismic measurement campaign aimed at the characterization of the crack area, and at the assessment of detection limitations of the different methods

  6. Linking ground motion measurements and macro-seismic observations in France: A case study based on the RAP (accelerometric) and BCSF (macro-seismic) databases

    International Nuclear Information System (INIS)

    Lesueur, Ch.

    2011-01-01

    Comparison between accelerometric and macro-seismic observations is made for three mw∼4.5 earthquakes of eastern France between 2003 and 2005. Scalar and spectral instrumental parameters are processed from the accelerometric data recorded by nine accelerometric stations located between 29 km and 180 km from the epicentres. Macro-seismic data are based on the French internet reports. In addition to the individual macro-seismic intensity, analysis of the internal correlation between the encoded answers highlights four predominant fields of questions, bearing different physical meanings: 1) 'vibratory motions of small objects', 2) 'displacement and fall of objects', 3) 'acoustic noise', and 4) 'personal feelings'. Best correlations between macro-seismic and instrumental observations are obtained when the macro-seismic parameters are averaged over 10 km radius circles around each station. macro-seismic intensities predicted by published pgv-intensity relationships quite agree with the observed intensities, contrary to those based on pga. The correlations between the macro-seismic and instrumental data, for intensities between ii and v (ems-98), show that pgv is the instrumental parameter presenting the best correlation with all macro-seismic parameters. The correlation with response spectra, exhibits clear frequency dependence over a limited frequency range [0.5-33 hz]. Horizontal and vertical components are significantly correlated with macro-seismic parameters between 1 and 10 hz, a range corresponding to both natural frequencies of most buildings and high energy content in the seismic ground motion. Between 10 and 25 hz, a clear lack of correlation between macro-seismic and instrumental data is observed, while beyond 25 hz the correlation coefficient increases, approaching that of the PGA correlation level. (author)

  7. Experimental measurement at the seismic station Ostrava-Krásné Pole (OKC): preliminary results and remarks on site effect at the studied locality

    Czech Academy of Sciences Publication Activity Database

    Lednická, Markéta; Rušajová, Jana

    2016-01-01

    Roč. 13, č. 2 (2016), s. 137-147 ISSN 1214-9705 R&D Projects: GA MŠk LM2010008; GA ČR GP13-07027P Institutional support: RVO:68145535 Keywords : seismic station OKC * spectral ratio * site effect Subject RIV: JM - Building Engineering Impact factor: 0.699, year: 2016 https://www.irsm.cas.cz/index.php?page=acta_content_doi&id_cislo=17

  8. Permafrost Active Layer Seismic Interferometry Experiment (PALSIE).

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knox, Hunter Anne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); James, Stephanie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lee, Rebekah [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cole, Chris [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    We present findings from a novel field experiment conducted at Poker Flat Research Range in Fairbanks, Alaska that was designed to monitor changes in active layer thickness in real time. Results are derived primarily from seismic data streaming from seven Nanometric Trillium Posthole seismometers directly buried in the upper section of the permafrost. The data were evaluated using two analysis methods: Horizontal to Vertical Spectral Ratio (HVSR) and ambient noise seismic interferometry. Results from the HVSR conclusively illustrated the method's effectiveness at determining the active layer's thickness with a single station. Investigations with the multi-station method (ambient noise seismic interferometry) are continuing at the University of Florida and have not yet conclusively determined active layer thickness changes. Further work continues with the Bureau of Land Management (BLM) to determine if the ground based measurements can constrain satellite imagery, which provide measurements on a much larger spatial scale.

  9. Seismic risk control of nuclear power plants using seismic protection systems in stable continental regions: The UK case

    Energy Technology Data Exchange (ETDEWEB)

    Medel-Vera, Carlos, E-mail: cbmedel@uc.cl; Ji, Tianjian, E-mail: tianjian.ji@manchester.ac.uk

    2016-10-15

    Highlights: • Strategies to reduce seismic risk for nuclear power stations in the UK are analysed. • Efficiency of devices to reduce risk: viscous-based higher than hysteretic-based. • Scenario-based incremental dynamic analysis is introduced for use in nuclear stations. • Surfaces of seismic unacceptable performance for nuclear stations are proposed. - Abstract: This article analyses three different strategies on the use of seismic protection systems (SPS) for nuclear power plants (NPPs) in the UK. Such strategies are based on the experience reported elsewhere of seismically protected nuclear reactor buildings in other stable continental regions. Analyses are conducted using an example of application based on a 1000 MW Pressurised Water Reactor building located in a representative UK nuclear site. The efficiency of the SPS is probabilistically assessed to achieve possible risk reduction for both rock and soil sites in comparison with conventionally constructed NPPs. Further analyses are conducted to study how the reduction of risk changes when all controlling scenarios of the site are included. This is done by introducing a scenario-based incremental dynamic analysis aimed at the generation of surfaces for unacceptable performance of NPPs as a function of earthquake magnitude (M{sub w}) and distance-to-site (R{sub epi}). General guidelines are proposed to potentially use SPS in future NPPs in the UK. Such recommendations can be used by the British nuclear industry in the future development of 12 new reactors to be built in the next two decades to generate 16 GWe of new nuclear capacity.

  10. Hanford Quarter Seismic Report - 98C Seismicity On and Near the Hanford Site, Pasco Basin, Washington: April 1, 1998 Through June 30, 1998

    Energy Technology Data Exchange (ETDEWEB)

    DC Hartshorn, SP Reidel, AC Rohay

    1998-10-23

    Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the U.S. Department of Energy and its contractors. The staff also locates aud identifies sources of seismic activity and monitors changes in the hi~orical pattern of seismic activity at the Hanford Site. The data are. compiled archived, and published for use by the Hanford Site for waste management Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of zin earthquake on the Hanford Site. The HSN and Ihe Eastern Washington Regional Network (EN/RN) consist-of 42 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. The operational rate for the third quarter of FY 1998 for stations in the HSN was 99.99%. The operational rate for the third quarter of FY 1998 for stations of the EWRN was 99.95%. For the third quarter of FY 1998, the acquisition computer triggered 133 times. Of these triggers 11 were local earthquakes: 5 (45Yo) in the Columbia River Basalt Group, 2(1 8%) in the pre-basalt sediments, and 4 (36%) in the crystalline basement. The geologic and tectonic environments where these earthquakes occurred are discussed in this report.

  11. Seismic risk map for Southeastern Brazil

    International Nuclear Information System (INIS)

    Mioto, J.A.

    1984-01-01

    During the last few years, some studies regarding seismic risk were prepared for three regions of Brazil. They were carried on account of two basic interests: first, toward the seismic history and recurrence of Brazilian seismic events; second, in a way as to provide seismic parameters for the design and construction of hydro and nuclear power plants. The first seismic risk map prepared for the southeastern region was elaborated in 1979 by 6he Universidade de Brasilia (UnB-Brasilia Seismological Station). In 1981 another seismic risk map was completed on the basis of seismotectonic studies carried out for the design and construction of the Nuclear power plants of Itaorna Beach (Angra dos Reis, Rio de Janeiro) by IPT (Mining and Applied Geology Division). In Brazil, until 1984, seismic studies concerning hydro and nuclear power plants and other civil construction of larger size did not take into account the seismic events from the point of view of probabilities of seismic recurrences. Such analysis in design is more important than the choice of a level of intensity or magnitude, or adoption of a seismicity level ased on deterministic methods. In this way, some considerations were made, concerning the use of seisms in Brazilian designs of hydro and nuclear power plants, as far as seismic analysis is concerned, recently altered over the current seismic risk panorama. (D.J.M.) [pt

  12. Bayesian Inference for Signal-Based Seismic Monitoring

    Science.gov (United States)

    Moore, D.

    2015-12-01

    Traditional seismic monitoring systems rely on discrete detections produced by station processing software, discarding significant information present in the original recorded signal. SIG-VISA (Signal-based Vertically Integrated Seismic Analysis) is a system for global seismic monitoring through Bayesian inference on seismic signals. By modeling signals directly, our forward model is able to incorporate a rich representation of the physics underlying the signal generation process, including source mechanisms, wave propagation, and station response. This allows inference in the model to recover the qualitative behavior of recent geophysical methods including waveform matching and double-differencing, all as part of a unified Bayesian monitoring system that simultaneously detects and locates events from a global network of stations. We demonstrate recent progress in scaling up SIG-VISA to efficiently process the data stream of global signals recorded by the International Monitoring System (IMS), including comparisons against existing processing methods that show increased sensitivity from our signal-based model and in particular the ability to locate events (including aftershock sequences that can tax analyst processing) precisely from waveform correlation effects. We also provide a Bayesian analysis of an alleged low-magnitude event near the DPRK test site in May 2010 [1] [2], investigating whether such an event could plausibly be detected through automated processing in a signal-based monitoring system. [1] Zhang, Miao and Wen, Lianxing. "Seismological Evidence for a Low-Yield Nuclear Test on 12 May 2010 in North Korea". Seismological Research Letters, January/February 2015. [2] Richards, Paul. "A Seismic Event in North Korea on 12 May 2010". CTBTO SnT 2015 oral presentation, video at https://video-archive.ctbto.org/index.php/kmc/preview/partner_id/103/uiconf_id/4421629/entry_id/0_ymmtpps0/delivery/http

  13. Design and commissioning of the Seismicity Network of Darkhovein Nuclear Power Plant (IR360)

    International Nuclear Information System (INIS)

    Aram, M. R.

    2012-01-01

    The study of micro seismicity and monitoring the micro seismic for the purpose of surveying the existing faults treatments and recognition of blind faults and other active tectonic structures in various phases of constructing the important structures, specially nuclear power plants, is unavoidable. According to IAEA safety guides and US-NRC regulatory guides, suitable instrumentation must be provided so that the seismic response of nuclear power plant features importantly from the safety point of view. According to R.G. 1.165 seismic monitoring by a network of seismic stations in the site area should be established as soon as possible after the site selection. Also, it is necessary to shutdown the nuclear power plant if vibratory ground motion exceeds the operating basis earthquake. The current research demonstrates the field works and studies for locating the local seismograph network in Darkhovein nuclear power plant. After the official studies and the primary visit of the old seismograph stations it was found that the mentioned network doesn't cover completely the geological structures around the power plant. Therefore, new locations have been introduced through the field investigation and computational methods of optimization. In positioning the new stations, places with the least amount of noise and the best coverage for seismic sources were selected. The modeling with considering an imaginative station at the selected places shows that the thresholds of the complete records of earthquakes around Darkhovein site is under the magnitude 1 (about 0.8).

  14. Seismic switch for strong motion measurement

    Science.gov (United States)

    Harben, P.E.; Rodgers, P.W.; Ewert, D.W.

    1995-05-30

    A seismic switching device is described that has an input signal from an existing microseismic station seismometer and a signal from a strong motion measuring instrument. The seismic switch monitors the signal level of the strong motion instrument and passes the seismometer signal to the station data telemetry and recording systems. When the strong motion instrument signal level exceeds a user set threshold level, the seismometer signal is switched out and the strong motion signal is passed to the telemetry system. The amount of time the strong motion signal is passed before switching back to the seismometer signal is user controlled between 1 and 15 seconds. If the threshold level is exceeded during a switch time period, the length of time is extended from that instant by one user set time period. 11 figs.

  15. Crustal structure and Seismic Hazard studies in Nigeria from ambient noise and earthquakes

    Science.gov (United States)

    Kadiri, U. A.

    2016-12-01

    The crust, upper Mantle and seismic hazard studies have been carried out in Nigeria using noise and earthquake data. The data were acquired from stations in Nigeria and international Agencies. Firstly, known depths of sediments in the Lower Benue Trough (LBT) were collected from wells; Resonance frequency (Fo) and average shear-wave velocities (Vs) were then computed using Matlab. Secondly, average velocities were estimated from noise cross-correlation along seismic stations. Thirdly, the moho depths beneath Ife, Kaduna and Nsukka stations were estimated, as well as Vp/Vs ratio using 2009 earthquake with epicenter in Nigeria. Finally, Statistical and Probabilistic Seismic Hazard Assessment (PSHA) were used to compute seismic hazard parameters in Nigeria and its surroundings. The results showed that, soils on the LBT with average shear wave velocity of about 5684m/s would experience more amplification in case of an earthquake, compared to the basement complex in Nigeria. The Vs beneath the seismic stations in Nigeria were also estimated as 288m/s, 1019m/s, 940.6m/s and 255.02m/s in Ife, Nsukka, Awka, and Abakaliki respectively. The average velocity along the station paths was 4.5km/secs, and the Vp, Vs for depths 100-500km profile in parts of South West Nigeria increased from about 5.83-6.42Km/sec and 3.48-6.31km/s respectively with Vp/Vs ratio decreasing from 1.68 to 1.02. Statistical analysis revealed a trend of increasing earthquake occurrence along the Mid-Atlantic Ridge and tending to West African region. The analysis of PSHA shows the likelihood of earthquakes with different magnitudes occurring in Nigeria and other parts West Africa in future. This work is aimed at addressing critical issues regarding sites effect characterization, improved earthquake location and robust seismic hazards assessment for planning in the choice of sites for critical facilities in Nigeria. Keywords: Sediment thickness, Resonance Frequency, Average Velocity, Seismic Hazard, Nigeria

  16. Heysham II/Torness power stations: Seismic qualification of core structures and boilers

    International Nuclear Information System (INIS)

    Shepherd, D.J.

    1990-01-01

    For the advanced gas cooled reactors at Heysham II and Torness the seismic qualification of the core and support structures and boilers posed special problems. In each case the response was highly non-linear due to impacting. Within the core itself there are many thousands of degrees of freedom each dominated by impacting during the seismic event and these impact forces are transmitted to the support structure. The boilers, although supported and located in the design case by linear systems, have their motion during the seismic event controlled by seismic restraints and other components which introduce substantial impacting during seismic excitation. For both these important components a substantial programme of testing was carried out to validate an analysis approach. This testing and correlation with analysis is described in detail for both components. In the case of the core the qualification was based upon a non-linear code AGRCORE which was specifically developed to handle the large number of impact degrees of freedom for this component. The implementation of this code is also described together with a brief summary of results. The boiler analysis was ultimately carried out using conventional finite difference codes and the implementation of these together with a summary of results is also presented. (author). 13 figs, 1 tab

  17. Seismic Performance of CAP1400 Nuclear Power Station considering Foundation Uplift

    Directory of Open Access Journals (Sweden)

    Ling-Yun Peng

    2018-01-01

    Full Text Available Under earthquake action, the reinforced concrete structure at the edge of the CAP1400 nuclear power plant foundation slab will be uplifted. In order to determine the seismic performance of this structure, a 1 : 12 scale shaking table test model was fabricated using gypsum as simulated concrete in order to meet scaled design requirements. By testing this model, the seismic response of the structure with consideration of the foundation uplift was obtained. Numerical analyses of the test model and the prototype structure were conducted to gain a better understanding of the structural seismic performance. When subjected to earthquakes, the foundation slab of the nuclear power plant experiences a slight degree of uplift but remains in the elastic stage due to the weight of the structure above, which provides an antioverturning moment. The numerical simulation is in general agreement with the test results, suggesting numerical simulations could be accurately employed in place of physical tests. The superstructure displacement response was found not to affect the safety of adjacent structures, and the seismic performance of the structure was shown to meet the relevant design requirements, demonstrating that this approach to modelling can serve as a design basis for the CAP1400 nuclear power demonstration project.

  18. Seismic network at the Olkiluoto site and microearthquake observations in 2002-2013

    International Nuclear Information System (INIS)

    Saari, J.; Malm, M.

    2014-05-01

    This report describes the structure and operation of Posiva's seismic network after the comprehensive upgrade performed in 2013 and presents a summary of its micro-earthquake observations in 2002 - 2013. Excavation of the underground rock characterisation facility called ONKALO started in 2004. Before that, in February 2002, Posiva Oy established a local seismic network of six stations on the island of Olkiluoto. The number of seismic stations has increased gradually and communication, hardware and software have developed in over ten years. The upgrade in 2013 included data transmission, the equipment in several seismic stations, the server responsible for the data processing in Olkiluoto and software applied in operation and analysis of observations. After the upgrade Posiva's permanent seismic network consists of 17 seismic stations and 21 triaxial sensors. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas, of which the larger one, the seismic semi-regional area, includes the Olkiluoto island and its surroundings. The aim is to monitor explosions and tectonic earthquakes in regional scale inside that area. All the expected excavation induced events are assumed to occur inside the smaller target area, the seismic ONKALO block, which is a 2 km x 2 km x 2 km cube surrounding the ONKALO. An additional task of monitoring is related to safeguarding of the construction of the ONKALO.In the beginning the network monitored tectonic earthquakes in order to characterise the undisturbed baseline of seismicity in Olkiluoto. After August 2004, the network also monitored excavation induced seismicity. The first three excavation induced earthquakes were recorded in September 2005. At the moment the total number of excavation induced earthquakes is 17. During the same time about 10 000 excavation blasts were located. The

  19. Seismic recording at the Los Medanos area of Southeastern New Mexico, 1974-1975

    International Nuclear Information System (INIS)

    Sanford, A.R.; Johansen, S.J.; Caravella, F.J.; Ward, R.M.

    1976-01-01

    The objective has been to determine if low-level seismic activity is occurring at or near the proposed nuclear waste repository in southeastern New Mexico. The research involved installation and maintenance of a continuously recording seismograph at the Los Medanos site and interpretation of the seismic events detected by that station. The following topics are discussed: (1) a description of the seismic instrumentation and its performance; (2) statistics on the local and regional earthquakes detected by the seismograph station at the Los Medanos site; (3) special studies on the seismic events associated with rockfalls at the National Potash Co. Eddy County Mine on July 26, 1972 and November 28, 1974; and (4) improved estimates of recurrence intervals for major earthquakes likely to effect the Los Medanos site

  20. Multiple Seismic Array Observations for Tracing Deep Tremor Activity in Western Shikoku, Japan

    Science.gov (United States)

    Takeda, T.; Matsuzawa, T.; Shiomi, K.; Obara, K.

    2011-12-01

    Deep non-volcanic tremors become very active during episodic slow-slip events in western Japan and Cascadia. The episodic tremor and slow-slip events in western Shikoku, Japan, occur at a typical interval of 6 months. Recently, it has been reported that tremor migration activity is complex and shows different migrating directions depending on time scales (Ghosh et al., 2010). Such characteristics of tremor are important to understand the mechanism of tremor and the relationship between tremor and SSEs. However it is difficult to determine the location of tremors with high accuracy because tremors show faint signals and make the identification of P/S-wave arrivals difficult. Seismic array analysis is useful to evaluate tremor activity, especially to estimate the arrival direction of seismic energy (e.g. Ueno et al., 2010, Ghosh et al., 2010), as it can distinguish multiple tremor sources occurring simultaneously. Here, we have conducted seismic array observation and analyzed seismic data during tremor activity by applying the MUSIC method to trace tremor location and its migration in western Shikoku. We have installed five seismic arrays in western Shikoku since January 2011. One of the arrays contains 30 stations with 3-component seismometers with a natural frequency of 2 Hz (Type-L array). The array aperture size is 2 km and the mean interval between stations is approximately 200 m. Each of the other arrays (Type-S array) contains 9 seismic stations with the same type of seismometers of the Type-L array, and is deployed surrounding the Type-L array. The small array aperture size is 800 m and its mean station interval is approximately 150 m. All array stations have recorded continuous waveform data at a sampling of 200Hz. In May 2011, an episodic tremor and a short-term slip event occurred for the first time during the observation period. We could retrieve the array seismic data during the whole tremor episode. The analysis of data from the type-L array confirms

  1. Seismic risk assessment of a BWR: status report

    International Nuclear Information System (INIS)

    Chuang, T.Y.; Bernreuter, D.L.; Wells, J.E.; Johnson, J.J.

    1985-02-01

    The seismic risk methodology developed in the US NRC Seismic Safety Margins Research Program (SSMRP) was demonstrated by its application to the Zion nuclear power plant, a pressurized water reactor (PWR). A detailed model of Zion, including systems analysis models (initiating events, event trees, and fault trees), SSI and structure models, and piping models was developed and analyzed. The SSMRP methodology can equally be applied to a boiling water reactor (BWR). To demonstrate its applicability, to identify fundamental differences in seismic risk between a PWR and a BWR, and to provide a basis of comparison of seismic risk between a PWR and a BWR when analyzed with comparable methodology and assumptions, a seismic risk analysis is being performed on the LaSalle County Station nuclear power plant

  2. Source-Type Identification Analysis Using Regional Seismic Moment Tensors

    Science.gov (United States)

    Chiang, A.; Dreger, D. S.; Ford, S. R.; Walter, W. R.

    2012-12-01

    Waveform inversion to determine the seismic moment tensor is a standard approach in determining the source mechanism of natural and manmade seismicity, and may be used to identify, or discriminate different types of seismic sources. The successful applications of the regional moment tensor method at the Nevada Test Site (NTS) and the 2006 and 2009 North Korean nuclear tests (Ford et al., 2009a, 2009b, 2010) show that the method is robust and capable for source-type discrimination at regional distances. The well-separated populations of explosions, earthquakes and collapses on a Hudson et al., (1989) source-type diagram enables source-type discrimination; however the question remains whether or not the separation of events is universal in other regions, where we have limited station coverage and knowledge of Earth structure. Ford et al., (2012) have shown that combining regional waveform data and P-wave first motions removes the CLVD-isotropic tradeoff and uniquely discriminating the 2009 North Korean test as an explosion. Therefore, including additional constraints from regional and teleseismic P-wave first motions enables source-type discrimination at regions with limited station coverage. We present moment tensor analysis of earthquakes and explosions (M6) from Lop Nor and Semipalatinsk test sites for station paths crossing Kazakhstan and Western China. We also present analyses of smaller events from industrial sites. In these sparse coverage situations we combine regional long-period waveforms, and high-frequency P-wave polarity from the same stations, as well as from teleseismic arrays to constrain the source type. Discrimination capability with respect to velocity model and station coverage is examined, and additionally we investigate the velocity model dependence of vanishing free-surface traction effects on seismic moment tensor inversion of shallow sources and recovery of explosive scalar moment. Our synthetic data tests indicate that biases in scalar

  3. Development of real time monitor system displaying seismic waveform data observed at seafloor seismic network, DONET, for disaster management information

    Science.gov (United States)

    Horikawa, H.; Takaesu, M.; Sueki, K.; Takahashi, N.; Sonoda, A.; Miura, S.; Tsuboi, S.

    2014-12-01

    Mega-thrust earthquakes are anticipated to occur in the Nankai Trough in southwest Japan. In the source areas, we have deployed seafloor seismic network, DONET (Dense Ocean-floor Network System for Earthquake and Tsunamis), in 2010 in order to monitor seismicity, crustal deformations, and tsunamis. DONET system consists of totally 20 stations, which is composed of six kinds of sensors, including strong-motion seismometers and quartz pressure gauges. Those stations are densely distributed with an average spatial interval of 15-20 km and cover near the trench axis to coastal areas. Observed data are transferred to a land station through a fiber-optical cable and then to JAMSTEC (Japan Agency for Marine-Earth Science and Technology) data management center through a private network in real time. After 2011 off the Pacific coast of Tohoku Earthquake, each local government close to Nankai Trough try to plan disaster prevention scheme. JAMSTEC will disseminate DONET data combined with research accomplishment so that they will be widely recognized as important earthquake information. In order to open DONET data observed for research to local government, we have developed a web application system, REIS (Real-time Earthquake Information System). REIS is providing seismic waveform data to some local governments close to Nankai Trough as a pilot study. As soon as operation of DONET is ready, REIS will start full-scale operation. REIS can display seismic waveform data of DONET in real-time, users can select strong motion and pressure data, and configure the options of trace view arrangement, time scale, and amplitude. In addition to real-time monitoring, REIS can display past seismic waveform data and show earthquake epicenters on the map. In this presentation, we briefly introduce DONET system and then show our web application system. We also discuss our future plans for further developments of REIS.

  4. Dynamic analysis of electric equipment for nuclear power stations under seismic loads

    International Nuclear Information System (INIS)

    Buck, K.E.; Bodisco, U. von; Winkler, K.

    1977-01-01

    The response spectrum method, generally accepted as the most practical method for linear seismic analysis of power station components, is here applied in conjunction with the finite element method to electric components. The fully dynamic analysis based on the superposition of the natural modes as carried out for an electronics cabinet and for transmitter supports is outlined and selected results are presented. Several different methods are in use for the superposition of the contributions of the different modes. Here addition of absolute values, the square-root of the sum of squares, and a mixed method taking account of closely spaced modes is applied. For different structures, the degree of conservativity is thus demonstrated, the largest difference in the stresses computed by the different methods being approximately 30%. For structures whose natural frequencies are in the spectrum range with zero period response, a simplified response analysis using static loads is often carried out. This is demonstrated for the electronics cabinet and transmitter mountings, and the results are compared with the fully dynamic analyses. It is seen that this 'pseudo-dynamic' analysis yields useful approximations for the distributions of stresses. Practical details of the structural models as well as results are presented for several switchgear and electronics cabinets

  5. An Expedient but Fascinating Geophysical Chimera: The Pinyon Flat Seismic Strain Point Array

    Science.gov (United States)

    Langston, C. A.

    2016-12-01

    The combination of a borehole Gladwin Tensor Strain Meter (GTSM) and a co-located three component broadband seismometer (BB) can theoretically be used to determine the propagation attributes of P-SV waves in vertically inhomogeneous media such as horizontal phase velocity and azimuth of propagation through application of wave gradiometry. A major requirement for this to be successful is to have well-calibrated strain and seismic sensors to be able to rely on using absolute wave amplitude from both systems. A "point" seismic array is constructed using the PBO GTSM station B084 and co-located BB seismic stations from an open array experiment deployed by UCSD as well as PFO station at the Pinyon Flat facility. Site amplitude statics for all three ground motion components are found for the 14-element (13 PY stations + PFO), small aperture seismic array using data from 47 teleseisms recorded from 2014 until present. Precision of amplitude measurement at each site is better than 0.2% for vertical components, 0.5% for EW components, and 1% for NS components. Relative amplitudes among sites of the array are often better than 1% attesting to the high quality of the instrumentation and installation. The wavefield and related horizontal strains are computed for the location of B084 using a second order Taylor's expansion of observed waveforms from moderate ( M4) regional events. The computed seismic array areal, differential, and shear strains show excellent correlation in both phase and amplitude with those recorded by B084 when using the calibration matrix previously determined using teleseismic strains from the entire ANZA seismic network. Use of the GTSM-BB "point" array significantly extends the bandwidth of gradiometry calculations over the small-aperture seismic array by nearly two orders of magnitude from 0.5 Hz to 0.01 Hz. In principle, a seismic strain point array could be constructed from every PBO GTSM with a co-located seismometer to help serve earthquake early

  6. Ambient seismic noise levels: A survey of the permanent and temporary seismographic networks in Morocco, North Africa

    Science.gov (United States)

    El Fellah, Y.; Khairy Abd Ed-Aal, A.; El Moudnib, L.; Mimoun, H.; Villasenor, A.; Gallart, J.; Thomas, C.; Elouai, D.; Mimoun, C.; Himmi, M.

    2013-12-01

    Abstract The results, of a conducted study carried out to analyze variations in ambient seismic noise levels at sites of the installed broadband stations in Morocco, North Africa, are obtained. The permanent and the temporary seismic stations installed in Morocco of the Scientific Institute ( IS, Rabat, Morocco), institute de Ciencias de la Tierra Jaume almera (ICTJA, Barcelona, Spain) and Institut für Geophysik (Munster, Germany) were used in this study. In this work, we used 23 broadband seismic stations installed in different structural domains covering all Morocco from south to north. The main purposes of the current study are: 1) to present a catalog of seismic background noise spectra for Morocco obtained from recently installed broadband stations, 2) to assess the effects of experimental temporary seismic vault construction, 3) to determine the time needed for noise at sites to stabilize, 4) to establish characteristics and origin of seismic noise at those sites. We calculated power spectral densities of background noise for each component of each broadband seismometer deployed in the different investigated sites and then compared them with the high-noise model and low-noise Model of Peterson (1993). All segments from day and night local time windows were included in the calculation without parsing out earthquakes. The obtained results of the current study could be used forthcoming to evaluate permanent station quality. Moreover, this study could be considered as a first step to develop new seismic noise models in North Africa not included in Peterson (1993). Keywords Background noise; Power spectral density; Model of Peterson; Scientific Institute; Institute de Ciencias de la Tierra Jaume almera; Institut für Geophysik

  7. Seismic safety of building structures of NPP Kozloduy III

    International Nuclear Information System (INIS)

    Varbanov, G.I.; Kostov, M.K.; Stefanov, D.D.; Kaneva, A.D.

    2005-01-01

    In the proposed paper is presented a general summary of the analyses carried out to evaluate the dynamic behavior and to assess the seismic safety of some safety related building structures of NPP Kozloduy. The design seismic loads for the site of Kozloduy NPP has been reevaluated and increased during and after the construction of investigated Units 5 and 6. Deterministic and probabilistic approaches are applied to assess the seismic vulnerability of the investigated structures, taking into account the newly defined seismic excitations. The presented results show sufficient seismic safety for the studied critical structures and good efficiency of the seismic upgrading. The applicability of the investigated structures at sites with some higher seismic activities is discussed. The presented study is dealing mainly with the civil structures of the Reactor building, Turbine hall, Diesel Generator Station and Water Intake Structure. (authors)

  8. Recent Progress of Seismic Observation Networks in Japan

    Science.gov (United States)

    Okada, Y.

    2013-04-01

    Before the occurrence of disastrous Kobe earthquake in 1995, the number of high sensitivity seismograph stations operated in Japan was nearly 550 and was concentrated in the Kanto and Tokai districts, central Japan. In the wake of the Kobe earthquake, Japanese government has newly established the Headquarters for Earthquake Research Promotion and started the reconstruction of seismic networks to evenly cover the whole Japan. The basic network is composed of three seismographs, i.e. high sensitivity seismograph (Hi-net), broadband seismograph (F-net), and strong motion seismograph (K-NET). A large majority of Hi-net stations are also equipped with a pair of strong motion sensors at the bottom of borehole and the ground surface (KiK-net). A plenty of high quality data obtained from these networks are circulated at once and is producing several new seismological findings as well as providing the basis for the Earthquake Early Warning system. In March 11, 2011, "Off the Pacific coast of Tohoku Earthquake" was generated with magnitude 9.0, which records the largest in the history of seismic observation in Japan. The greatest disaster on record was brought by huge tsunami with nearly 20 thousand killed or missing people. We are again noticed that seismic observation system is quite poor in the oceanic region compared to the richness of it in the inland region. In 2012, NIED has started the construction of ocean bottom seismic and tsunami observation network along the Japan Trench. It is planned to layout 154 stations with an average spacing of 30km, each of which is equipped with an accelerometer for seismic observation and a water pressure gauge for tsunami observation. We are expecting that more rapid and accurate warning of earthquake and tsunami becomes possible by this observing network.

  9. Recent Progress of Seismic Observation Networks in Japan

    International Nuclear Information System (INIS)

    Okada, Y

    2013-01-01

    Before the occurrence of disastrous Kobe earthquake in 1995, the number of high sensitivity seismograph stations operated in Japan was nearly 550 and was concentrated in the Kanto and Tokai districts, central Japan. In the wake of the Kobe earthquake, Japanese government has newly established the Headquarters for Earthquake Research Promotion and started the reconstruction of seismic networks to evenly cover the whole Japan. The basic network is composed of three seismographs, i.e. high sensitivity seismograph (Hi-net), broadband seismograph (F-net), and strong motion seismograph (K-NET). A large majority of Hi-net stations are also equipped with a pair of strong motion sensors at the bottom of borehole and the ground surface (KiK-net). A plenty of high quality data obtained from these networks are circulated at once and is producing several new seismological findings as well as providing the basis for the Earthquake Early Warning system. In March 11, 2011, 'Off the Pacific coast of Tohoku Earthquake' was generated with magnitude 9.0, which records the largest in the history of seismic observation in Japan. The greatest disaster on record was brought by huge tsunami with nearly 20 thousand killed or missing people. We are again noticed that seismic observation system is quite poor in the oceanic region compared to the richness of it in the inland region. In 2012, NIED has started the construction of ocean bottom seismic and tsunami observation network along the Japan Trench. It is planned to layout 154 stations with an average spacing of 30km, each of which is equipped with an accelerometer for seismic observation and a water pressure gauge for tsunami observation. We are expecting that more rapid and accurate warning of earthquake and tsunami becomes possible by this observing network.

  10. Local seismic network at the Olkiluoto site. Annual report for 2010

    International Nuclear Information System (INIS)

    Saari, J.; Malm, M.

    2011-11-01

    Excavation of the underground characterisation facility (the ONKALO) started in 2004. Before that, in February 2002, Posiva Oy established a local seismic network of six stations on the island of Olkiluoto. After that the number of seismic stations has increased gradually. In 2010 Posiva's permanent seismic network consists of 15 seismic stations and 20 triaxial sensors. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas. The larger target area, called seismic semiregional area, covers the Olkiluoto Island and its surroundings. The purpose is to monitor explosions and tectonic earthquakes in regional scale inside that area. The smaller target area is called the seismic ONKALO block, which is a 2 km *2 km *2 km cube surrounding the ONKALO. It is assumed that all the expected excavation induced events occur within this volume. At the moment the seismic ONKALO block includes ten seismic stations. An additional task of monitoring is related to safeguarding of the ONKALO. This report gives the results of microseismic monitoring during 2010. In March 2010, the seismic network was upgraded by a new triaxial borehole seismometer in order to improve the sensitivity and the depth resolution inside the ONKALO block. The sensor is the second one inside the ONKALO. New PC for data processing and analysis with the new version of Linux operating system was installed. Also all software packages for data processing and analysis and for visualization were upgraded. The network has operated continuously in 2010. Altogether 1089 events have been located in the Olkiluoto area, in reported time period. Most of them (943) are explosions occurred inside the seismic semi-regional area and especially inside the seismic ONKALO block (895 events). The magnitudes of the observed explosions inside the semi-regional area range from M L = -1

  11. Seismic-design questions typify nuclear obstacles

    International Nuclear Information System (INIS)

    Strauss, S.D.

    1979-01-01

    The trade-off between safe design of nuclear power plants and cost is considered. As an example, seismic protection problems at the Beaver Valley station of Duquesne Light Co. and their resolution by Stone and Webster Engineering are discussed

  12. Seismic hazard maps for earthquake-resistant construction designs

    International Nuclear Information System (INIS)

    Ohkawa, Izuru

    2004-01-01

    Based on the idea that seismic phenomena in Japan varying in different localities are to be reflected in designing specific nuclear facilities in specific site, the present research program started to make seismic hazard maps representing geographical distribution of seismic load factors. First, recent research data on historical earthquakes and materials on active faults in Japan have been documented. Differences in character due to different localities are expressed by dynamic load in consideration of specific building properties. Next, hazard evaluation corresponding to seismic-resistance factor is given as response index (spectrum) of an adequately selected building, for example a nuclear power station, with the help of investigation results of statistical analysis. (S. Ohno)

  13. Capturing the WUnder: Using weather stations and WeatherUnderground to increase middle school students' understanding and interest in science

    Science.gov (United States)

    Schild, K. M.; Dunne, P.

    2014-12-01

    New models of elementary- and middle-school level science education are emerging in response to the need for science literacy and the development of the Next Generation Science Standards. One of these models is fostered through the NSF's Graduate Teaching Fellows in K-12 Education (GK-12) program, which pairs a graduate fellow with a science teacher at a local school for an entire school year. In our project, a PhD Earth Sciences student was paired with a local middle school science teacher with the goal of installing a weather station, and incorporating the station data into the 8th grade science curriculum. Here we discuss how we were able to use a school weather station to introduce weather and climate material, engage and involve students in the creative process of science, and motivate students through inquiry-based lessons. In using a weather station as the starting point for material, we were able to make science tangible for students and provide an opportunity for each student to experience the entire process of scientific inquiry. This hands-on approach resulted in a more thorough understanding the system beyond a knowledge of the components, and was particularly effective in challenging prior weather and climate misconceptions. We were also able to expand the reach of the lessons by connecting with other weather stations in our region and even globally, enabling the students to become members of a larger system.

  14. Seismic evaluation and strengthening of Bohunice nuclear power plant structures

    International Nuclear Information System (INIS)

    Shipp, J.G.; Short, S.A.; Grief, T.; Borov, V.; Kuzma, J.

    2001-01-01

    A seismic assessment and strengthening investigation is being performed for selected structures at the Bohunice V1 Nuclear Power Plant in Slovakia. Structures covered in this paper include the reactor building complex and the emergency generator station. The emergency generator station is emphasized in the paper as work is nearly complete while work on the reactor building complex is ongoing at this time. Seismic evaluation and strengthening work is being performed by a cooperative effort of Siemens and EQE along with local contractors. Seismic input is the interim Review Level Earthquake (horizontal peak ground acceleration of 0.3 g). The Bohunice V1 reactor building complex is a WWER 4401230 nuclear power plant that was originally built in the mid-1970s but had extensive seismic upgrades in 1991. Siemens has performed three dimensional dynamic analyses of the reactor building complex to develop seismic demand in structural elements. EQE is assessing seismic capacities of structural elements and developing strengthening schemes, where needed. Based on recent seismic response analyses for the interim Review Level Earthquake which account for soil-structure interaction in a rigorous manner, the 1991 seismic upgrade has been found to be inadequate in both member/connection strength and in providing complete load paths to the foundation. Additional strengthening is being developed. The emergency generator station was built in the 1970s and is a two-story unreinforced brick masonry (URM) shear wall building above grade with a one story reinforced concrete shear wall basement below grade. Seismic analyses and testing of the URM walls has been performed to assess the need for building strengthening. Required structural strengthening for in-plane forces consists of revised and additional vertical steel framing and connections, stiffening of horizontal roof bracing, and steel connections between the roof and supporting walls and pointing of two interior transverse URM

  15. Improved Seismic Acquisition System and Data Processing for the Italian National Seismic Network

    Science.gov (United States)

    Badiali, L.; Marcocci, C.; Mele, F.; Piscini, A.

    2001-12-01

    A new system for acquiring and processing digital signals has been developed in the last few years at the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The system makes extensive use of the internet communication protocol standards such as TCP and UDP which are used as the transport highway inside the Italian network, and possibly in a near future outside, to share or redirect data among processes. The Italian National Seismic Network has been working for about 18 years equipped with vertical short period seismometers and transmitting through analog lines, to the computer center in Rome. We are now concentrating our efforts on speeding the migration towards a fully digital network based on about 150 stations equipped with either broad band or 5 seconds sensors connected to the data center partly through wired digital communication and partly through satellite digital communication. The overall process is layered through intranet and/or internet. Every layer gathers data in a simple format and provides data in a processed format, ready to be distributed towards the next layer. The lowest level acquires seismic data (raw waveforms) coming from the remote stations. It handshakes, checks and sends data in LAN or WAN according to a distribution list where other machines with their programs are waiting for. At the next level there are the picking procedures, or "pickers", on a per instrument basis, looking for phases. A picker spreads phases, again through the LAN or WAN and according to a distribution list, to one or more waiting locating machines tuned to generate a seismic event. The event locating procedure itself, the higher level in this stack, can exchange information with other similar procedures. Such a layered and distributed structure with nearby targets allows other seismic networks to join the processing and data collection of the same ongoing event, creating a virtual network larger than the original one. At present we plan to cooperate with other

  16. Local seismic network at the Olkiluoto site. Annual report for 2011

    International Nuclear Information System (INIS)

    Saari, J.; Malm, M.

    2012-06-01

    This report gives the results of microseismic monitoring during 2011. Excavation of the underground characterisation facility called ONKALO started in 2004. Before that, in February 2002, Posiva Oy established a local seismic network of six stations on the island of Olkiluoto. After that the number of seismic stations has increased gradually. In 2011 Posiva's permanent seismic network consists of 15 seismic stations and 20 triaxial sensors. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas. The larger target area, called seismic semiregional area, covers the Olkiluoto Island and its surroundings. The purpose is to monitor explosions and tectonic earthquakes in regional scale inside that area. The smaller target area is called the seismic ONKALO block, which is a 2 km x 2 km x 2 km cube surrounding ONKALO. It is assumed that all the expected excavation induced events occur within this volume. At the moment the seismic ONKALO block includes ten seismic stations. An additional task of monitoring is related to safeguarding of the construction of ONKALO. The configuration of the seismic network as well as the software packages applied in data processing and analyses have remained during the previous year. The design model of ONKALO and the brittle fault zone model of the Olkiluoto of the seismic visualization package Jdi were upgraded in 2011. The network has operated nearly continuously. There was a 14 minutes and 30 second long operation failure in December 2011. That was the first network operation failure in five years. Altogether 1223 events have been located in the Olkiluoto area, in the reported time period. Most of them (1098) are explosions that occurred inside the seismic semiregional area and especially inside the seismic ONKALO block (1064 events). The magnitudes of the observed explosions inside the semi

  17. Local seismic network at the Olkiluoto site. Annual report for 2011

    Energy Technology Data Exchange (ETDEWEB)

    Saari, J.; Malm, M. [AF-Consult Oy, Espoo (Finland)

    2012-06-15

    This report gives the results of microseismic monitoring during 2011. Excavation of the underground characterisation facility called ONKALO started in 2004. Before that, in February 2002, Posiva Oy established a local seismic network of six stations on the island of Olkiluoto. After that the number of seismic stations has increased gradually. In 2011 Posiva's permanent seismic network consists of 15 seismic stations and 20 triaxial sensors. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas. The larger target area, called seismic semiregional area, covers the Olkiluoto Island and its surroundings. The purpose is to monitor explosions and tectonic earthquakes in regional scale inside that area. The smaller target area is called the seismic ONKALO block, which is a 2 km x 2 km x 2 km cube surrounding ONKALO. It is assumed that all the expected excavation induced events occur within this volume. At the moment the seismic ONKALO block includes ten seismic stations. An additional task of monitoring is related to safeguarding of the construction of ONKALO. The configuration of the seismic network as well as the software packages applied in data processing and analyses have remained during the previous year. The design model of ONKALO and the brittle fault zone model of the Olkiluoto of the seismic visualization package Jdi were upgraded in 2011. The network has operated nearly continuously. There was a 14 minutes and 30 second long operation failure in December 2011. That was the first network operation failure in five years. Altogether 1223 events have been located in the Olkiluoto area, in the reported time period. Most of them (1098) are explosions that occurred inside the seismic semiregional area and especially inside the seismic ONKALO block (1064 events). The magnitudes of the observed explosions inside the

  18. Modern Adaptive Analytics Approach to Lowering Seismic Network Detection Thresholds

    Science.gov (United States)

    Johnson, C. E.

    2017-12-01

    Modern seismic networks present a number of challenges, but perhaps most notably are those related to 1) extreme variation in station density, 2) temporal variation in station availability, and 3) the need to achieve detectability for much smaller events of strategic importance. The first of these has been reasonably addressed in the development of modern seismic associators, such as GLASS 3.0 by the USGS/NEIC, though some work still remains to be done in this area. However, the latter two challenges demand special attention. Station availability is impacted by weather, equipment failure or the adding or removing of stations, and while thresholds have been pushed to increasingly smaller magnitudes, new algorithms are needed to achieve even lower thresholds. Station availability can be addressed by a modern, adaptive architecture that maintains specified performance envelopes using adaptive analytics coupled with complexity theory. Finally, detection thresholds can be lowered using a novel approach that tightly couples waveform analytics with the event detection and association processes based on a principled repicking algorithm that uses particle realignment for enhanced phase discrimination.

  19. Earthquakes from peninsular India : data from the Gauribidanur seismic array

    International Nuclear Information System (INIS)

    Gangrade, B.K.; Prasad, A.G.V.; Sharma, R.D.

    1987-01-01

    Arrival times of the P and S wave signals recorded at the Gauribidanur seismic array from earthquakes in the neighbouring areas in peninsular India have been analysed to estimate their locations (latitudes and longitudes of the epicenters), magnitudes and origin times. Considering typical inaccuracies in the observed data, uncertainties in the estimated epicentral parameters have been illustrated. Using a crustal model, which has been specifically derived for the region around the array, expected arrival times of these signals at other important seismic stations (Kodaikanal, Hyderabad, Poona, New Delhi and Shillong) have been computed for identifying events at these stations in order to determine accurate arrival times at these stations. Due to a higher signal detection capability of the Gauribidanur array, the number of events given in this catalogue is much greater than that detected by these stations. The M S magnitude estimates of events detected at the Hyderabad station have been used to obtain a magnitude scale for Gauribidanur. Origin times, epicentral locations and magnitudes of these events are listed in this report. 10 refs., 3 figures, 3 tables. (author)

  20. Aseismic design of the Heysham II Nuclear Power Station

    International Nuclear Information System (INIS)

    Day, J.W.

    1983-01-01

    A brief description of the seismic criteria established for use with the Steam Generating Heavy Water Reactor (SCHWR) and taken for the Heysham II Project is given. The qualification strategy adopted for Heysham II is described, and a brief overview is given of some of the more important design changes required for seismic purposes on that station

  1. Seismic PRA of a BWR plant

    International Nuclear Information System (INIS)

    Nishio, Masahide; Fujimoto, Haruo

    2014-01-01

    Since the occurrence of nuclear power plant accidents in the Fukushima Daichi nuclear power station, the regulatory framework on severe accident (SA) has been discussed in Japan. The basic concept is to typify and identify the accident sequences leading to core/primary containment vessel (PCV) damage and to implement SA measures covering internal and external events extensively. As Japan is an earthquake-prone country and earthquakes and tsunami are important natural external events for nuclear safety of nuclear power plants, JNES performed the seismic probabilistic risk assessment (PRA) on a typical nuclear power plant and evaluated the dominant accident sequences leading to core/PCV damage to discuss dominant scenarios of severe accident (SA). The analytical models and the results of level-1 seismic PRA on a 1,100 MWe BWR-5 plant are shown here. Seismic PRA was performed for a typical BWR5 plant. Initiating events with large contribution to core damage frequency are the loss of all AC powers (station blackout) and the large LOCA. The top of dominant accident sequences is the simultaneous occurrence of station blackout and large LOCA. Important components to core damage frequency are electric power supply equipment. It needs to keep in mind that the results are influenced on site geologic characteristic to a greater or lesser. In the process of analysis, issues such as conservative assumptions related to damages of building or structure and success criteria for excessive LOCA are left to be resolved. These issues will be further studied including thermal hydric analysis in the future. (authors)

  2. Mednet: the very broad-band seismic network for the Mediterranean

    International Nuclear Information System (INIS)

    Boschi, E.; Giardini, D.; Morelli, A.

    1991-01-01

    Mednet is the very broad-band seismic network installed by the Istituto Nazionale di Geofisica (ING) in countries of the mediterranean area, with a final goal of 12-15 stations and a spacing of about 1000 km between stations. The project started in 1987 and will be completed within 1992. Mednet is motivated both by research interest and by seismic hazard monitoring; it will allow to define the structure of the mediterranean region to a high detail, to study properties of the seismic source for intermediate and large events, and to apply this knowledge to procedures of civil protection. To reach its goals, the network has been designed following the highest technical standards: STS-1/VBB sensors, Quanterra 24 bits A/D converters with 140 dB dynamic range, real-time telemetry. Five sites are now operational in Italy (L'Aquila, Bardonecchia and Villasalto) and in northern african countries (Midelt, Morocco; Gafsa, Tunisia); other sites are under construction in Pakistan (Islamabad), Irak (Rutba) and Egypt (Kottamya), while locations are examined for stations in Greece, Jugoslavia and Algeria. The centre of the mednet network is the data center (MDC) in Rome; its tasks include data collection, verification, quality control, archivial and dissemination, monitoring of station performance, event detection, routine determination of source parameters. Data distribution will follow the guidelines set by FDSN, and will be coordinated with other international network projects

  3. State-of-the-art report on the current status of methodologies for seismic PSA

    International Nuclear Information System (INIS)

    1998-01-01

    There has never been an earthquake sufficiently damaging to any operating U.S. nuclear power station to cause safety concerns. In the past decade, there have been two very destructive earthquakes that were near enough to nuclear power stations to have caused at least temporary world-wide concern: the large Armenian earthquake of November, 1988, and the large Japanese earthquake near Kobe in January, 1995. However, in each case, these earthquakes produced only minor ground motion at the operating nuclear stations located close enough to merit some examination: in each case, inspections revealed essentially no damage, because the actual ground motions at the nuclear-plant sites were in both cases quite small and well within the design basis. Nor has there ever been any other earthquake known to have damaged a nuclear power station. Therefore, the published historical record is not adequate for the analysis discussed here. The frequency of potential earthquake-initiated core-damage accidents at a given nuclear-power station can only be known from calculations, using a combination of real-earthquake data, test data, models of various phenomena, and systems analysis. Despite the lack of actual earthquake experience at nuclear-power stations, almost every full-scope probabilistic safety analysis (PSA) that has examined earthquake-initiated accidents at nuclear power stations has found that this category represents one of the important initiator groups. Occasionally, one of the earthquake-initiated sequences is among the few largest contributors to calculated core-damage frequency and/or off-site risk. Of course, it is important to keep in mind that PSAs calculate a residual risk, which is judged to be acceptable by the regulatory authorities, and that the seismic contribution to this residual risk is what is being discussed here. Usually the potential accident sequences identified in the PSAs are very plant-specific in character, such that the specific vulnerability is

  4. A plan for location calibration of IMS stations and near Kazakhstan

    International Nuclear Information System (INIS)

    Richards, P.G.; Kim, W.-Yo.; Khalturin, V.I.

    2001-01-01

    For purposes of monitoring compliance with the Comprehensive Nuclear Test-Ban Treaty, it is desirable to be able to locate seismic events routinely to within an uncertainty not greater than 1000 square km. From more than five years of experience with publication of the Reviewed Event Bulletin (REB) by the Prototype International Data Centre (PIDC), resulting in estimated locations for more than 100,000 seismic events, it is apparent that improved location accuracy is needed in order to reduce uncertainties below 1000 square km. In this paper, we outline a three-year program of applied research which commenced in March 2000 and which has the goal of achieving improved REB locations based upon data to be contributed to the International Data Centre from 30 IMS stations in Eastern Asia. Our first efforts will focus on the four IMS seismographic stations in Kazakhstan (AKT, BRV, KUR, MAK), together with IMS stations ZAL in Russia and AAK in Kyrgyzstan. Following the recommendations of two 'IMS Location Calibration Workshops' held in Oslo, Norway, in 1999 and 2000, our approach is to generate station-specific travel times for each observable seismic phase, as a function of distance and azimuth (and depth, where possible). Such travel times are obtained on the basis of (i) early studies based mainly on earthquake data (e.g. Nersesov and Rautian, 1964), (ii) Deep Seismic Sounding, and (iii) recent studies of nuclear and chemical explosions. We are also using (iv) an empirical approach in which phases are picked at IMS stations, for so-called Ground Truth events whose location is known quite accurately on the basis of additional data, obtained for example from local and regional networks. (author)

  5. Excitation of seismic waves by a tornado

    Science.gov (United States)

    Valovcin, A.; Tanimoto, T.; Twardzik, C.

    2016-12-01

    Tornadoes are among the most common natural disasters to occur in the United States. Various methods are currently used in tornado forecasting, including surface weather stations, weather balloons and satellite and Doppler radar. These methods work for detecting possible locations of tornadoes and funnel clouds, but knowing when a tornado has touched down still strongly relies on reports from spotters. Studying tornadoes seismically offers an opportunity to know when a tornado has touched down without requiring an eyewitness report. With the installation of Earthscope's Transportable Array (TA), there have been an increased number of tornadoes that have come within close range of seismometers. We have identified seismic signals corresponding to three tornadoes that occurred in 2011 in the central US. These signals were recorded by the TA station closest to each of the tornado tracks. For each tornado, the amplitudes of the seismic signals increase when the storm is in contact with the ground, and continue until the tornado lifts off some time later. This occurs at both high and low frequencies. In this study we will model the seismic signal generated by a tornado at low frequencies (below 0.1 Hz). We will begin by modeling the signal from the Joplin tornado, an EF5 rated tornado which occurred in Missouri on May 22, 2011. By approximating the tornado as a vertical force, we model the generated signal as the tornado moves along its track and changes in strength. By modeling the seismic waveform generated by a tornado, we can better understand the seismic-excitation process. It could also provide a way to quantitatively compare tornadoes. Additional tornadoes to model include the Calumet-El Reno-Piedmont-Guthrie (CEPG) and Chickasa-Blanchard-Newcastle (CBN) tornadoes, both of which occurred on May 24, 2011 in Oklahoma.

  6. Design and Implementation of the National Seismic Monitoring Network in the Kingdom of Bhutan

    Science.gov (United States)

    Ohmi, S.; Inoue, H.; Chophel, J.; Pelgay, P.; Drukpa, D.

    2017-12-01

    Bhutan-Himalayan district is located along the plate collision zone between Indian and Eurasian plates, which is one of the most seismically active region in the world. Recent earthquakes such as M7.8 Gorkha Nepal earthquake in April 25, 2015 and M6.7 Imphal, India earthquake in January 3, 2016 are examples of felt earthquakes in Bhutan. However, there is no permanent seismic monitoring system ever established in Bhutan, whose territory is in the center of the Bhutan-Himalayan region. We started establishing permanent seismic monitoring network of minimum requirements and intensity meter network over the nation. The former is composed of six (6) observation stations in Bhutan with short period weak motion and strong motion seismometers as well as three (3) broad-band seismometers, and the latter is composed of twenty intensity meters located in every provincial government office. Obtained data are transmitted to the central processing system in the DGM office in Thimphu in real time. In this project, DGM will construct seismic vault with their own budget which is approved as the World Bank project, and Japan team assists the DGM for site survey of observation site, designing the observation vault, and designing the data telemetry system as well as providing instruments for the observation such as seismometers and digitizers. We already started the operation of the six (6) weak motion stations as well as twenty (20) intensity meter stations. Additionally, the RIMES (Regional Integrated Multi-hazard Early Warning System for Africa and Asia) is also providing eight (8) weak motion stations and we are keeping close communication to operate them as one single seismic monitoring network composed of fourteen (14) stations. This network will be definitely utilized for not only for seismic disaster mitigation of the country but also for studying the seismotectonics in the Bhutan-Himalayan region which is not yet precisely revealed due to the lack of observation data in the

  7. Seismic velocity structure in the lower crust beneath the seismic belt in the San-in district, Southwest Japan

    Science.gov (United States)

    Tsuda, H.; Iio, Y.; Shibutani, T.

    2017-12-01

    In the San-in district in Southwest Japan, a linear distribution of the epicenters of microearthquakes is seen along the coast of the Japan Sea (Fig. 1). The linear distribution is known as the seismic belt in the San-in district. Large earthquakes also occurred in the seismic belt. What localizes the earthquake distribution in the San-in district which is located far from the plate boundary? We thought that the model proposed by Iio et al. (2002, 2004) could answer this question. The model is as follows. Viscosity is low in a part of the lower crust, which is called `weak zone'. Stress and strain are concentrated in the upper crust right above the weak zone, due to concentrated deformation in the weak zone, and thus earthquakes occur there. To verify whether the weak zone exists in the lower crust beneath the seismic belt, we estimated the seismic velocity structure there by travel-time tomography. We used the tomography program, FMTOMO (Rawlinson et al., 2006). For the model space, we set the latitude range of 33°-36°N, the longitude range of 131°-136°E (Fig. 1), and the depth range of 0-81 km. The grid intervals are 0.1°×0.1°×7 km. We used arrival times picked by Japan Meteorological Agency (JMA) for earthquakes that occurred in the study area. In addition, we used arrival times manually picked at stations in and around the San-in district for earthquakes that occurred within the Philippine Sea Slab, because they are not included in the JMA data. Since the seismic waves from those earthquakes to the stations in the San-in district pass through the lower crust beneath the San-in district, we expect that these data can improve the resolution there. We revealed that low velocity anomalies exist in the lower crust beneath the seismic belt (Fig. 1). It is inferred that the region of low velocity anomalies is characterized by low viscosity, since velocities of rocks decrease with temperature and/or water content. Therefore, the results of this study support

  8. Performance Assessment of a Solar powered Air Quality and Weather Station Placed on a School Rooftop in Hong Kong

    Science.gov (United States)

    Summary of compact, roof version of a Village Green Project station installed on a secondary school rooftop in Hong Kong. Preliminary comparison of the station's data against nearby regulatory monitors are summarized.

  9. Triggered Seismicity in Utah from the November 3, 2002, Denali Fault Earthquake

    Science.gov (United States)

    Pankow, K. L.; Nava, S. J.; Pechmann, J. C.; Arabasz, W. J.

    2002-12-01

    Coincident with the arrival of the surface waves from the November 3, 2002, Mw 7.9 Denali Fault, Alaska earthquake (DFE), the University of Utah Seismograph Stations (UUSS) regional seismic network detected a marked increase in seismicity along the Intermountain Seismic Belt (ISB) in central and north-central Utah. The number of earthquakes per day in Utah located automatically by the UUSS's Earthworm system in the week following the DFE was approximately double the long-term average during the preceding nine months. From these preliminary data, the increased seismicity appears to be characterized by small magnitude events (M = 3.2) and concentrated in five distinct spatial clusters within the ISB between 38.75°and 42.0° N. The first of these earthquakes was an M 2.2 event located ~20 km east of Salt Lake City, Utah, which occurred during the arrival of the Love waves from the DFE. The increase in Utah earthquake activity at the time of the arrival of the surface waves from the DFE suggests that these surface waves triggered earthquakes in Utah at distances of more than 3,000 km from the source. We estimated the peak dynamic shear stress caused by these surface waves from measurements of their peak vector velocities at 43 recording sites: 37 strong-motion stations of the Advanced National Seismic System and six broadband stations. (The records from six other broadband instruments in the region of interest were clipped.) The estimated peak stresses ranged from 1.2 bars to 3.5 bars with a mean of 2.3 bars, and generally occurred during the arrival of Love waves of ~15 sec period. These peak dynamic shear stress estimates are comparable to those obtained from recordings of the 1992 Mw 7.3 Landers, California, earthquake in regions where the Landers earthquake triggered increased seismicity. We plan to present more complete analyses of UUSS seismic network data, further testing our hypothesis that the DFE remotely triggered seismicity in Utah. This hypothesis is

  10. A test of a global seismic system for monitoring earthquakes and underground nuclear explosions

    International Nuclear Information System (INIS)

    Bowman, J.R.; Muirhead, K.; Spiliopoulos, S.; Jepsen, D.; Leonard, M.

    1993-01-01

    Australia is a member of the Group of Scientific Experts (GSE) to consider international cooperative measures to detect and identify events, an ad hoc group of the United Nations Conference on Disarmament. The GSE conducted a large-scale technical test (GSETT-2) from 22 April to 9 June 1991 that focused on the exchange and analysis of seismic parameter and waveform data. Thirty-four countries participated in GSETT-2, and data were contributed from 60 stations on all continents. GSETT-2 demonstrated the feasibility of collecting and transmitting large volumes (around 1 giga-byte) of digital data around the world, and of producing a preliminary bulletin of global seismicity within 48 hours and a final bulletin within 7 days. However, the experiment also revealed the difficulty of keeping up with the flow of data and analysis with existing resources. The Final Event Bulletins listed 3715 events for the 42 recording days of the test, about twice the number reported routinely by another international agency 5 months later. The quality of the Final Event Bulletin was limited by the uneven spatial distribution of seismic stations that contributed to GSETT-2 and by the ambiguity of associating phases detected by widely separated stations to form seismic events. A monitoring system similar to that used in GSETT-2 could provide timely and accurate reporting of global seismicity. It would need an improved distribution of stations, application of more conservative event formation rules and further development of analysis software. 8 refs., 9 figs

  11. Local seismic network at the Olkiluoto site. Annual report 2002-2004

    Energy Technology Data Exchange (ETDEWEB)

    Saari, J. [Enprima Oy, Vantaa (Finland)

    2005-09-15

    In Olkiluoto, Posiva Oy has operated a local seismic network since February 2002. In the beginning, the network consisted of six seismic stations. Later, in June 2004, the seismic network was expanded with two new seismic stations. At that time started the excavation of the underground characterisation facility (the ONKALO) and the basic operation procedure was changed more suitable for the demands of the new situation. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The studies include both tectonic and excavation-induced microearthquakes. An additional task of monitoring is related to safeguarding of the ONKALO. This report gives the results of microseismic monitoring during the years 2002 - 2004. Also the changes in the structure and the operation procedure of the network are described. The network has operated nearly continuously. The longest interruption occurred 16.-17.6.2004, when two new seismic stations were installed in the network and the operation procedure was changed. Altogether 757 events have been located in the Olkiluoto area. The magnitudes of the observed events range from ML = -3.5 to ML = 1.2. All of them are explosions or other artificial events. So far, none of the 757 observed events can be classified as microearthquakes. Five of the events have characteristics that make the origin of the recorded signal uncertain. They are quite unlikely microearthquakes, but they are not typical examples of artificial seismic signals either. When the experience and the data set of the Olkiluoto microearthquakes increase the identification of events will be more definite. Evidence of activity that would has influence on the safety of the ONKALO, have not found. (orig.)

  12. Local seismic network at the Olkiluoto site. Annual report 2002-2004

    International Nuclear Information System (INIS)

    Saari, J.

    2005-09-01

    In Olkiluoto, Posiva Oy has operated a local seismic network since February 2002. In the beginning, the network consisted of six seismic stations. Later, in June 2004, the seismic network was expanded with two new seismic stations. At that time started the excavation of the underground characterisation facility (the ONKALO) and the basic operation procedure was changed more suitable for the demands of the new situation. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The studies include both tectonic and excavation-induced microearthquakes. An additional task of monitoring is related to safeguarding of the ONKALO. This report gives the results of microseismic monitoring during the years 2002 - 2004. Also the changes in the structure and the operation procedure of the network are described. The network has operated nearly continuously. The longest interruption occurred 16.-17.6.2004, when two new seismic stations were installed in the network and the operation procedure was changed. Altogether 757 events have been located in the Olkiluoto area. The magnitudes of the observed events range from ML = -3.5 to ML = 1.2. All of them are explosions or other artificial events. So far, none of the 757 observed events can be classified as microearthquakes. Five of the events have characteristics that make the origin of the recorded signal uncertain. They are quite unlikely microearthquakes, but they are not typical examples of artificial seismic signals either. When the experience and the data set of the Olkiluoto microearthquakes increase the identification of events will be more definite. Evidence of activity that would has influence on the safety of the ONKALO, have not found. (orig.)

  13. Monitoring El Hierro submarine volcanic eruption events with a submarine seismic array

    Science.gov (United States)

    Jurado, Maria Jose; Molino, Erik; Lopez, Carmen

    2013-04-01

    A submarine volcanic eruption took place near the southernmost emerged land of the El Hierro Island (Canary Islands, Spain), from October 2011 to February 2012. The Instituto Geografico Nacional (IGN) seismic stations network evidenced seismic unrest since July 2012 and was a reference also to follow the evolution of the seismic activity associated with the volcanic eruption. From the beginning of the eruption a geophone string was installed less than 2 km away from the new volcano, next to La Restinga village shore, to record seismic activity related to the volcanic activity, continuously and with special interest on high frequency events. The seismic array was endowed with 8, high frequency, 3 component, 250 Hz, geophone cable string with a separation of 6 m between them. The analysis of the dataset using spectral techniques allows the characterization of the different phases of the eruption and the study of its dynamics. The correlation of the data analysis results with the observed sea surface activity (ash and lava emission and degassing) and also with the seismic activity recorded by the IGN field seismic monitoring system, allows the identification of different stages suggesting the existence of different signal sources during the volcanic eruption and also the posteruptive record of the degassing activity. The study shows that the high frequency capability of the geophone array allow the study of important features that cannot be registered by the standard seismic stations. The accumulative spectral amplitude show features related to eruptive changes.

  14. Hydraulically Induced Seismicity in South-Eastern Brazil Linked to Water Wells

    Science.gov (United States)

    Convers, J.; Assumpcao, M.; Barbosa, J. R.

    2017-12-01

    While hydraulic stimulus on seismic activity is most commonly associated with hydraulic fracturing processes, we find in SE Brazil a rare case of seismicity influenced by hydraulic stimulation linked to seasonal rain and water wells in a farming area. These are thought to be the main factors influencing the seasonal seismicity activity in Jurupema, a farming town located in the interior of the state of Sao Paulo, southern Brazil. With temporary seismic station deployments during 2016 and 2017, we analyze the seismicity in this area, its temporal and spatial distribution, and its association with the drilling of ground water wells in this particular area. In a region where water wells are often drilled to provide irrigation for farming, these are often perforated down to about 100 m depth, penetrating below the uppermost sandstone rock layer ( 50 m) into a fractured basaltic rock layer, reaching the confined aquifer within it. While the wells are constantly pumped during the dry season, during the course of the rainy season (when these are not being used), a possible infiltration into the confined basaltic aquifer, from both the rainwater and the upper sandstone aquifer, adds changes to the pore pressure of the fractured rock, and modifies the tectonic pre-stress conditions, to facilitate stress release mechanisms in pre-existing faults and cracks. With our temporary seismic station deployments, we not only examine the seismicity in this region during both 2016 and 2017, but we additionally compare its characteristics to the nearby Bebedouro case in an apparent induced seismic case of analogous source, and seismic activity with magnitudes up to 2.9 occurring between 2005 and 2010.

  15. Earthquake experience suggests new approach to seismic criteria

    International Nuclear Information System (INIS)

    Knox, R.

    1983-01-01

    Progress in seismic qualification of nuclear power plants as reviewed at the 4th Pacific Basin Nuclear Conference in Vancouver, September 1983, is discussed. The lack of experience of earthquakes in existing nuclear plants can be compensated by the growing experience of actual earthquake effects in conventional power plants and similar installations. A survey of the effects on four power stations, with a total of twenty generating units, in the area strongly shaken by the San Fernando earthquake in California in 1971 is reported. The Canadian approach to seismic qualification, international criteria, Canadian/Korean experience, safety related equipment, the Tadotsu test facility and seismic tests are discussed. (U.K.)

  16. Hanford annual first quarter seismic report, fiscal year 1998: Seismicity on and near the Hanford Site, Pasco Basin, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Hartshorn, D.C.; Reidel, S.P.; Rohay, A.C.

    1998-02-01

    Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the US Department of Energy and its contractors. The staff also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of an earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (EWRN) consist of 41 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. The operational rate for the first quarter of FY98 for stations in the HSN was 98.5%. The operational rate for the first quarter of FY98 for stations of the EWRN was 99.1%. For the first quarter of FY98, the acquisition computer triggered 184 times. Of these triggers 23 were local earthquakes: 7 in the Columbia River Basalt Group, and 16 in the crystalline basement. The geologic and tectonic environments where these earthquakes occurred are discussed in this report. The most significant earthquakes in this quarter were a series of six events which occurred in the Cold Creek depression (approximately 4 km SW of the 200 West Area), between November 6 and November 11, 1997. All events were deep (> 15 km) and were located in the crystalline basement. The first event was the largest, having a magnitude of 3.49 M{sub c}. Two events on November 9, 1997 had magnitudes of 2.81 and 2.95 M{sub c}, respectively. The other events had magnitudes between 0.7 and 1.2 M{sub c}.

  17. Evaluation of Fourier integral. Spectral analysis of seismic events

    International Nuclear Information System (INIS)

    Chitaru, Cristian; Enescu, Dumitru

    2003-01-01

    Spectral analysis of seismic events represents a method for great earthquake prediction. The seismic signal is not a sinusoidal signal; for this, it is necessary to find a method for best approximation of real signal with a sinusoidal signal. The 'Quanterra' broadband station allows the data access in numerical and/or graphical forms. With the numerical form we can easily make a computer program (MSOFFICE-EXCEL) for spectral analysis. (authors)

  18. Data Analysis of Seismic Sequence in Central Italy in 2016 using CTBTO- International Monitoring System

    Science.gov (United States)

    Mumladze, Tea; Wang, Haijun; Graham, Gerhard

    2017-04-01

    The seismic network that forms the International Monitoring System (IMS) of the Comprehensive Nuclear-test-ban Treaty Organization (CTBTO) will ultimately consist of 170 seismic stations (50 primary and 120 auxiliary) in 76 countries around the world. The Network is still under the development, but currently more than 80% of the network is in operation. The objective of seismic monitoring is to detect and locate underground nuclear explosions. However, the data from the IMS also can be widely used for scientific and civil purposes. In this study we present the results of data analysis of the seismic sequence in 2016 in Central Italy. Several hundred earthquakes were recorded for this sequence by the seismic stations of the IMS. All events were accurately located the analysts of the International Data Centre (IDC) of the CTBTO. In this study we will present the epicentral and magnitude distribution, station recordings and teleseismic phases as obtained from the Reviewed Event Bulletin (REB). We will also present a comparison of the database of the IDC with the databases of the European-Mediterranean Seismological Centre (EMSC) and U.S. Geological Survey (USGS). Present work shows that IMS data can be used for earthquake sequence analyses and can play an important role in seismological research.

  19. Teacher Directed Design: Content Knowledge, Pedagogy and Assessment under the Nevada K-12 Real-Time Seismic Network

    Science.gov (United States)

    Cantrell, P.; Ewing-Taylor, J.; Crippen, K. J.; Smith, K. D.; Snelson, C. M.

    2004-12-01

    Education professionals and seismologists under the emerging SUN (Shaking Up Nevada) program are leveraging the existing infrastructure of the real-time Nevada K-12 Seismic Network to provide a unique inquiry based science experience for teachers. The concept and effort are driven by teacher needs and emphasize rigorous content knowledge acquisition coupled with the translation of that knowledge into an integrated seismology based earth sciences curriculum development process. We are developing a pedagogical framework, graduate level coursework, and materials to initiate the SUN model for teacher professional development in an effort to integrate the research benefits of real-time seismic data with science education needs in Nevada. A component of SUN is to evaluate teacher acquisition of qualified seismological and earth science information and pedagogy both in workshops and in the classroom and to assess the impact on student achievement. SUN's mission is to positively impact earth science education practices. With the upcoming EarthScope initiative, the program is timely and will incorporate EarthScope real-time seismic data (USArray) and educational materials in graduate course materials and teacher development programs. A number of schools in Nevada are contributing real-time data from both inexpensive and high-quality seismographs that are integrated with Nevada regional seismic network operations as well as the IRIS DMC. A powerful and unique component of the Nevada technology model is that schools can receive "stable" continuous live data feeds from 100's seismograph stations in Nevada, California and world (including live data from Earthworm systems and the IRIS DMC BUD - Buffer of Uniform Data). Students and teachers see their own networked seismograph station within a global context, as participants in regional and global monitoring. The robust real-time Internet communications protocols invoked in the Nevada network provide for local data acquisition

  20. The Apollo passive seismic experiment

    Science.gov (United States)

    Latham, G. V.; Dorman, H. J.; Horvath, P.; Ibrahim, A. K.; Koyama, J.; Nakamura, Y.

    1979-01-01

    The completed data set obtained from the 4-station Apollo seismic network includes signals from approximately 11,800 events of various types. Four data sets for use by other investigators, through the NSSDC, are in preparation. Some refinement of the lunar model based on seismic data can be expected, but its gross features remain as presented two years ago. The existence of a small, molten core remains dependent upon the analysis of signals from a single, far-side impact. Analysis of secondary arrivals from other sources may eventually resolve this issue, as well as continued refinement of the magnetic field measurements. Evidence of considerable lateral heterogeneity within the moon continues to build. The mystery of the much meteoroid flux estimate derived from lunar seismic measurements, as compared with earth-based estimates, remains; although, significant correlations between terrestrial and lunar observations are beginning to emerge.

  1. Rayleigh wave tomography in North-China from ambient seismic noise

    OpenAIRE

    Fang, Lihua

    2010-01-01

    2008/2009 The theory and methodology of ambient noise tomography has been studied and applied to North-China successfully. Continuous vertical-component seismograms, spanning the period from January 1, 2007 to February 28, 2008 recorded by 190 broadband stations and 10 very broadband stations, have been used. The cross correlation technique has been applied to ambient noise data recorded by North-China Seismic Array for each station pairs of the array. Rayleigh wave group ve...

  2. RMT focal plane sensitivity to seismic network geometry and faulting style

    Science.gov (United States)

    Johnson, Kendra L.; Hayes, Gavin; Herrmann, Robert B.; Benz, Harley M.; McNamara, Daniel E.; Bergman, Eric A.

    2016-01-01

    Modern tectonic studies often use regional moment tensors (RMTs) to interpret the seismotectonic framework of an earthquake or earthquake sequence; however, despite extensive use, little existing work addresses RMT parameter uncertainty. Here, we quantify how network geometry and faulting style affect RMT sensitivity. We examine how data-model fits change with fault plane geometry (strike and dip) for varying station configurations. We calculate the relative data fit for incrementally varying geometries about a best-fitting solution, applying our workflow to real and synthetic seismograms for both real and hypothetical station distributions and earthquakes. Initially, we conduct purely observational tests, computing RMTs from synthetic seismograms for hypothetical earthquakes and a series of well-behaved network geometries. We then incorporate real data and station distributions from the International Maule Aftershock Deployment (IMAD), which recorded aftershocks of the 2010 MW 8.8 Maule earthquake, and a set of regional stations capturing the ongoing earthquake sequence in Oklahoma and southern Kansas. We consider RMTs computed under three scenarios: (1) real seismic records selected for high data quality; (2) synthetic seismic records with noise computed for the observed source-station pairings and (3) synthetic seismic records with noise computed for all possible station-source pairings. To assess RMT sensitivity for each test, we observe the ‘fit falloff’, which portrays how relative fit changes when strike or dip varies incrementally; we then derive the ranges of acceptable strikes and dips by identifying the span of solutions with relative fits larger than 90 per cent of the best fit. For the azimuthally incomplete IMAD network, Scenario 3 best constrains fault geometry, with average ranges of 45° and 31° for strike and dip, respectively. In Oklahoma, Scenario 3 best constrains fault dip with an average range of 46°; however, strike is best constrained

  3. Measurement of the Parameter Kappa, and Reevaluation of Kappa for Small to Moderate Earthquakes at Seismic Stations in the Vicinity of Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Biasi, Glenn; Anderson, John G

    2007-01-01

    The parameter kappa was defined by Anderson and Hough (1984) to describe the high-frequency spectral roll-off of the strong motion seismic spectrum. In the work of Su et al., (1996) the numerical value of kappa estimated for sites near Yucca Mountain was small (∼20 ms). The estimate obtained from these events has been applied through a rigorous methodology to develop design earthquake spectra with magnitude over 5.0. Smaller values of kappa lead to higher estimated ground motions in the methodology used by the Probabilistic Seismic Hazard Analysis (PSHA) for Yucca Mountain. An increase of 10 ms in kappa could result in a substantial decrease in the high frequency level of the predicted ground motions. Any parameter that plays such a critical role deserves close examination. Here, we study kappa and its associated uncertainties. The data set used by Su et al (1996) consisted of 12 M 2.8 to 4.5 earthquakes recorded at temporary stations deployed after the June 1992 Little Skull Mountain earthquake. The kappa elements of that study were revisited by Anderson and Su (MOL.20071203.0134) and substantially confirmed. One weakness of those studies is the limited data used. Few of these stations were on tuff or on Yucca Mountain itself. A decade of Southern Great Basin Digital Seismic Network (SGBDSN) recording has now yielded a larger body of on-scale, well calibrated digital ground motion records suitable for investigating kappa. We use the SGBDSN data to check some of the original assumptions, improve the statistical confidence of the conclusions, and determine values of kappa for stations on or near Yucca Mountain. The outstanding issues in kappa analysis, as they apply to Yucca Mountain, include: (1) The number itself. The kappa estimate near 20 msec from Su et al. (1996) and Anderson and Su (MOL.20071203.0134) is markedly smaller than is considered typical in California (Silva, 1995). The low kappa value has engineering consequences because when it is applied in

  4. Measurement of the Parameter Kappa, and Reevaluation of Kappa for Small to Moderate Earthquakes at Seismic Stations in the Vicinity of Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Biasi, Glenn; Anderson, John G

    2007-12-05

    The parameter kappa was defined by Anderson and Hough (1984) to describe the high-frequency spectral roll-off of the strong motion seismic spectrum. In the work of Su et al., (1996) the numerical value of kappa estimated for sites near Yucca Mountain was small (~20 ms). The estimate obtained from these events has been applied through a rigorous methodology to develop design earthquake spectra with magnitude over 5.0. Smaller values of kappa lead to higher estimated ground motions in the methodology used by the Probabilistic Seismic Hazard Analysis (PSHA) for Yucca Mountain. An increase of 10 ms in kappa could result in a substantial decrease in the high frequency level of the predicted ground motions. Any parameter that plays such a critical role deserves close examination. Here, we study kappa and its associated uncertainties. The data set used by Su et al (1996) consisted of 12 M 2.8 to 4.5 earthquakes recorded at temporary stations deployed after the June 1992 Little Skull Mountain earthquake. The kappa elements of that study were revisited by Anderson and Su (MOL.20071203.0134) and substantially confirmed. One weakness of those studies is the limited data used. Few of these stations were on tuff or on Yucca Mountain itself. A decade of Southern Great Basin Digital Seismic Network (SGBDSN) recording has now yielded a larger body of on-scale, well calibrated digital ground motion records suitable for investigating kappa. We use the SGBDSN data to check some of the original assumptions, improve the statistical confidence of the conclusions, and determine values of kappa for stations on or near Yucca Mountain. The outstanding issues in kappa analysis, as they apply to Yucca Mountain, include: 1. The number itself. The kappa estimate near 20 msec from Su et al. (1996) and Anderson and Su (MOL.20071203.0134) is markedly smaller than is considered typical in California (Silva, 1995). The low kappa value has engineering consequences because when it is applied in ground

  5. Undergraduates' Implementations of Learning Stations as Their Service Learning among Elementary School Students

    Science.gov (United States)

    Chien, Chin-Wen

    2017-01-01

    Service learning provides pre-service educators with a context for having hands-on field experience and also assists in understanding the theory and practice. This study discusses 7 undergraduates' implementations of learning stations as their service learning with 28 elementary school students. Through thematic data analysis of interviews,…

  6. Local seismic monitoring east and north of Toronto - Volume 1

    International Nuclear Information System (INIS)

    Mohajer, A.A.; Doughty, M.

    1996-08-01

    Monitoring of small magnitude ('micro') earthquakes in a dense local network is one of the techniques used to delineate currently active faults and seismic sources. The conventional wisdom is that smaller, but more frequent, seismic events normally occur on active fault planes and a log linear empirical relation between frequency and magnitude can be used to estimate the magnitude and recurrence (frequency) of the larger events. A program of site-specific seismic monitoring has been supported by the AECB since 1991, to investigate the feasibility of microearthquake detection in suburban areas of east Toronto in order to assess the rate activity of local events in the vicinity of the nuclear power plants at Pickering and Darlington. For deployment of the seismic stations at the most favorable locations an extensive background noise survey was carried out. This survey involved measuring and comparing the amplitude response of the ambient vibration caused by natural phenomena (e.g. wind blow, water flow, wave action) or human activities such as farming, mining and industrial work at 25 test sites. Subsequently, a five-station seismic network, with a 30 km aperture, was selected between the Pickering and Darlington nuclear power plants on Lake Ontario, to the south, and Lake Scugog to the north. The detection threshold obtained for two of the stations allows recording of local events M L =0-2, a magnitude range which is usually not detected by regional seismic networks. An analysis of several thousand triggered signals resulted in the identification of about 120 local events, which can not be assigned to any source other than the natural release of crustal stresses. The recurrence frequency of these microearthquakes shows a linear relationship which matches that of larger events in the last two centuries in this region. The preliminary results indicate that the stress is currently accumulating and is being released within clusters of small earthquakes

  7. The seismic project of the National Tsunami Hazard Mitigation Program

    Science.gov (United States)

    Oppenheimer, D.H.; Bittenbinder, A.N.; Bogaert, B.M.; Buland, R.P.; Dietz, L.D.; Hansen, R.A.; Malone, S.D.; McCreery, C.S.; Sokolowski, T.J.; Whitmore, P.M.; Weaver, C.S.

    2005-01-01

    In 1997, the Federal Emergency Management Agency (FEMA), National Oceanic and Atmospheric Administration (NOAA), U.S. Geological Survey (USGS), and the five western States of Alaska, California, Hawaii, Oregon, and Washington joined in a partnership called the National Tsunami Hazard Mitigation Program (NTHMP) to enhance the quality and quantity of seismic data provided to the NOAA tsunami warning centers in Alaska and Hawaii. The NTHMP funded a seismic project that now provides the warning centers with real-time seismic data over dedicated communication links and the Internet from regional seismic networks monitoring earthquakes in the five western states, the U.S. National Seismic Network in Colorado, and from domestic and global seismic stations operated by other agencies. The goal of the project is to reduce the time needed to issue a tsunami warning by providing the warning centers with high-dynamic range, broadband waveforms in near real time. An additional goal is to reduce the likelihood of issuing false tsunami warnings by rapidly providing to the warning centers parametric information on earthquakes that could indicate their tsunamigenic potential, such as hypocenters, magnitudes, moment tensors, and shake distribution maps. New or upgraded field instrumentation was installed over a 5-year period at 53 seismic stations in the five western states. Data from these instruments has been integrated into the seismic network utilizing Earthworm software. This network has significantly reduced the time needed to respond to teleseismic and regional earthquakes. Notably, the West Coast/Alaska Tsunami Warning Center responded to the 28 February 2001 Mw 6.8 Nisqually earthquake beneath Olympia, Washington within 2 minutes compared to an average response time of over 10 minutes for the previous 18 years. ?? Springer 2005.

  8. Mantle wedge structure beneath the Yamato Basin, southern part of the Japan Sea, revealed by long-term seafloor seismic observations

    Science.gov (United States)

    Shinohara, M.; Nakahigashi, K.; Yamashita, Y.; Yamada, T.; Mochizuki, K.; Shiobara, H.

    2016-12-01

    The Japanese Islands are located at subduction zones where Philippine Sea (PHS) plate subducts from the southeast beneath the Eurasian plate and the Pacific plate descends from the east beneath the PHS and Eurasian plates and have a high density of seismic stations. Many seismic tomography studies using land seismic station data were conducted to reveal the seismic structure. These studies discussed the relationship between heterogeneous structures and the release of fluids from the subducting slab, magma generation and movement in the subduction zone. However, regional tomography using the land station data did not have a sufficient resolution to image a deep structure beneath the Japan Sea.To obtain the deep structure, observations of natural earthquakes within the Japan Sea are essential. Therefore, we started the repeating long-term seismic observations using ocean bottom seismometers(OBSs) in the Yamato Basin from 2013 to 2016. We apply travel-time tomography method to the regional earthquake and teleseismic arrival-data recorded by OBSs and land stations. In this presentation, we will report the P and S wave tomographic images down to a depth of 300 km beneath the southern part of the Japan Sea. This study was supported by "Integrated Research Project on Seismic and Tsunami Hazards around the Sea of Japan" conducted by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan.

  9. Romanian Data Center: A modern way for seismic monitoring

    Science.gov (United States)

    Neagoe, Cristian; Marius Manea, Liviu; Ionescu, Constantin

    2014-05-01

    The main seismic survey of Romania is performed by the National Institute for Earth Physics (NIEP) which operates a real-time digital seismic network. The NIEP real-time network currently consists of 102 stations and two seismic arrays equipped with different high quality digitizers (Kinemetrics K2, Quanterra Q330, Quanterra Q330HR, PS6-26, Basalt), broadband and short period seismometers (CMG3ESP, CMG40T, KS2000, KS54000, KS2000, CMG3T,STS2, SH-1, S13, Mark l4c, Ranger, gs21, Mark l22) and acceleration sensors (Episensor Kinemetrics). The data are transmitted at the National Data Center (NDC) and Eforie Nord (EFOR) Seismic Observatory. EFOR is the back-up for the NDC and also a monitoring center for the Black Sea tsunami events. NIEP is a data acquisition node for the seismic network of Moldova (FDSN code MD) composed of five seismic stations. NIEP has installed in the northern part of Bulgaria eight seismic stations equipped with broadband sensors and Episensors and nine accelerometers (Episensors) installed in nine districts along the Danube River. All the data are acquired at NIEP for Early Warning System and for primary estimation of the earthquake parameters. The real-time acquisition (RT) and data exchange is done by Antelope software and Seedlink (from Seiscomp3). The real-time data communication is ensured by different types of transmission: GPRS, satellite, radio, Internet and a dedicated line provided by a governmental network. For data processing and analysis at the two data centers Antelope 5.2 TM is being used running on 3 workstations: one from a CentOS platform and two on MacOS. Also a Seiscomp3 server stands as back-up for Antelope 5.2 Both acquisition and analysis of seismic data systems produce information about local and global parameters of earthquakes. In addition, Antelope is used for manual processing (event association, calculation of magnitude, creating a database, sending seismic bulletins, calculation of PGA and PGV, etc.), generating

  10. Variations of Background Seismic Noise Before Strong Earthquakes, Kamchatka.

    Science.gov (United States)

    Kasimova, V.; Kopylova, G.; Lyubushin, A.

    2017-12-01

    The network of broadband seismic stations of Geophysical Service (Russian Academy of Science) works on the territory of Kamchatka peninsula in the Far East of Russia. We used continuous records on Z-channels at 21 stations for creation of background seismic noise time series in 2011-2017. Average daily parameters of multi-fractal spectra of singularity have been calculated at each station using 1-minute records. Maps and graphs of their spatial distribution and temporal changes were constructed at time scales from days to several years. The analysis of the coherent behavior of the time series of the statistics was considered. The technique included the splitting of seismic network into groups of stations, taking into account the coastal effect, the network configuration and the main tectonic elements of Kamchatka. Then the time series of median values of noise parameters from each group of stations were made and the frequency-time diagrams of the evolution of the spectral measure of the coherent behavior of four time series were analyzed. The time intervals and frequency bands of the maximum values showing the increase of coherence in the changes of all statistics were evaluated. The strong earthquakes with magnitudes M=6.9-8.3 occurred near the Kamchatka peninsula during the observations. The synchronous variations of the background noise parameters and increase in the coherent behavior of the median values of statistical parameters was shown before two earthquakes 2013 (February 28, Mw=6.9; May 24, Mw=8.3) within 3-9 months and before earthquake of January 30, 2016, Mw=7.2 within 3-6 months. The maximum effect of increased coherence in the range of periods 4-5.5 days corresponds to the time of preparation of two strong earthquakes in 2013 and their aftershock processes. Peculiarities in changes of statistical parameters at stages of preparation of strong earthquakes indicate the attenuation in high-amplitude outliers and the loss of multi-fractal properties in

  11. 100 years of seismic research on the Moho

    Science.gov (United States)

    Prodehl, Claus; Kennett, Brian; Artemieva, Irina M.; Thybo, Hans

    2013-12-01

    The detection of a seismic boundary, the “Moho”, between the outermost shell of the Earth, the Earth's crust, and the Earth's mantle by A. Mohorovičić was the consequence of increased insight into the propagation of seismic waves caused by earthquakes. This short history of seismic research on the Moho is primarily based on the comprehensive overview of the worldwide history of seismological studies of the Earth's crust using controlled sources from 1850 to 2005, by Prodehl and Mooney (2012). Though the art of applying explosions, so-called “artificial events”, as energy sources for studies of the uppermost crustal layers began in the early 1900s, its effective use for studying the entire crust only began at the end of World War II. From 1945 onwards, controlled-source seismology has been the major approach to study details of the crust and underlying crust-mantle boundary, the Moho. The subsequent description of history of controlled-source crustal seismology and its seminal results is subdivided into separate chapters for each decade, highlighting the major advances achieved during that decade in terms of data acquisition, processing technology, and interpretation methods. Since the late 1980s, passive seismology using distant earthquakes has played an increasingly important role in studies of crustal structure. The receiver function technique exploiting conversions between P and SV waves at discontinuities in seismic wavespeed below a seismic station has been extensively applied to the increasing numbers of permanent and portable broad-band seismic stations across the globe. Receiver function studies supplement controlled source work with improved geographic coverage and now make a significant contribution to knowledge of the nature of the crust and the depth to Moho.

  12. Passive seismic investigation of Harrat Rahat

    Energy Technology Data Exchange (ETDEWEB)

    Mellors, Robert J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-04-07

    Ambient noise correlation was applied to 18 months of continuous seismic data from 14 stations. The procedure of Bensen et al [2007] was followed with some changes to optimize signal-to-noise of the results. The 18 months of correlations (representing about 1 week of CPU time on a 12 core machine) were stacked and manually inspected to yield about 40 cross-correlations. These cross-correlations represent the Green’s function between the station pairs and will be analyzed in part two of this project to yield velocity structure.

  13. The AlpArray Seismic Network: A Large-Scale European Experiment to Image the Alpine Orogen

    Science.gov (United States)

    Hetényi, György; Molinari, Irene; Clinton, John; Bokelmann, Götz; Bondár, István; Crawford, Wayne C.; Dessa, Jean-Xavier; Doubre, Cécile; Friederich, Wolfgang; Fuchs, Florian; Giardini, Domenico; Gráczer, Zoltán; Handy, Mark R.; Herak, Marijan; Jia, Yan; Kissling, Edi; Kopp, Heidrun; Korn, Michael; Margheriti, Lucia; Meier, Thomas; Mucciarelli, Marco; Paul, Anne; Pesaresi, Damiano; Piromallo, Claudia; Plenefisch, Thomas; Plomerová, Jaroslava; Ritter, Joachim; Rümpker, Georg; Šipka, Vesna; Spallarossa, Daniele; Thomas, Christine; Tilmann, Frederik; Wassermann, Joachim; Weber, Michael; Wéber, Zoltán; Wesztergom, Viktor; Živčić, Mladen

    2018-04-01

    The AlpArray programme is a multinational, European consortium to advance our understanding of orogenesis and its relationship to mantle dynamics, plate reorganizations, surface processes and seismic hazard in the Alps-Apennines-Carpathians-Dinarides orogenic system. The AlpArray Seismic Network has been deployed with contributions from 36 institutions from 11 countries to map physical properties of the lithosphere and asthenosphere in 3D and thus to obtain new, high-resolution geophysical images of structures from the surface down to the base of the mantle transition zone. With over 600 broadband stations operated for 2 years, this seismic experiment is one of the largest simultaneously operated seismological networks in the academic domain, employing hexagonal coverage with station spacing at less than 52 km. This dense and regularly spaced experiment is made possible by the coordinated coeval deployment of temporary stations from numerous national pools, including ocean-bottom seismometers, which were funded by different national agencies. They combine with permanent networks, which also required the cooperation of many different operators. Together these stations ultimately fill coverage gaps. Following a short overview of previous large-scale seismological experiments in the Alpine region, we here present the goals, construction, deployment, characteristics and data management of the AlpArray Seismic Network, which will provide data that is expected to be unprecedented in quality to image the complex Alpine mountains at depth.

  14. Salton Trough Post-seismic Afterslip, Viscoelastic Response, and Contribution to Regional Hazard

    Science.gov (United States)

    Parker, J. W.; Donnellan, A.; Lyzenga, G. A.

    2012-12-01

    The El Mayor-Cucapah M7.2 April 4 2010 earthquake in Baja California may have affected accumulated hazard to Southern California cities due to loading of regional faults including the Elsinore, San Jacinto and southern San Andreas, faults which already have over a century of tectonic loading. We examine changes observed via multiple seismic and geodetic techniques, including micro seismicity and proposed seismicity-based indicators of hazard, high-quality fault models, the Plate Boundary Observatory GNSS array (with 174 stations showing post-seismic transients with greater than 1 mm amplitude), and interferometric radar maps from UAVSAR (aircraft) flights, showing a network of aseismic fault slip events at distances up to 60 km from the end of the surface rupture. Finite element modeling is used to compute the expected coseismic motions at GPS stations with general agreement, including coseismic uplift at sites ~200 km north of the rupture. Postseismic response is also compared, with GNSS and also with the CIG software "RELAX." An initial examination of hazard is made comparing micro seismicity-based metrics, fault models, and changes to coulomb stress on nearby faults using the finite element model. Comparison of seismicity with interferograms and historic earthquakes show aseismic slip occurs on fault segments that have had earthquakes in the last 70 years, while other segments show no slip at the surface but do show high triggered seismicity. UAVSAR-based estimates of fault slip can be incorporated into the finite element model to correct Coloumb stress change.

  15. Seismic site-response characterization of high-velocity sites using advanced geophysical techniques: application to the NAGRA-Net

    Science.gov (United States)

    Poggi, V.; Burjanek, J.; Michel, C.; Fäh, D.

    2017-08-01

    The Swiss Seismological Service (SED) has recently finalised the installation of ten new seismological broadband stations in northern Switzerland. The project was led in cooperation with the National Cooperative for the Disposal of Radioactive Waste (Nagra) and Swissnuclear to monitor micro seismicity at potential locations of nuclear-waste repositories. To further improve the quality and usability of the seismic recordings, an extensive characterization of the sites surrounding the installation area was performed following a standardised investigation protocol. State-of-the-art geophysical techniques have been used, including advanced active and passive seismic methods. The results of all analyses converged to the definition of a set of best-representative 1-D velocity profiles for each site, which are the input for the computation of engineering soil proxies (traveltime averaged velocity and quarter-wavelength parameters) and numerical amplification models. Computed site response is then validated through comparison with empirical site amplification, which is currently available for any station connected to the Swiss seismic networks. With the goal of a high-sensitivity network, most of the NAGRA stations have been installed on stiff-soil sites of rather high seismic velocity. Seismic characterization of such sites has always been considered challenging, due to lack of relevant velocity contrast and the large wavelengths required to investigate the frequency range of engineering interest. We describe how ambient vibration techniques can successfully be applied in these particular conditions, providing practical recommendations for best practice in seismic site characterization of high-velocity sites.

  16. A systematic analysis of directional site effects at stations of the Italian Seismic Network to test the role of local topography

    Science.gov (United States)

    Pischiutta, Marta; Cianfarra, Paola; Salvini, Francesco; Cara, Fabrizio; Vannoli, Paola

    2018-03-01

    Directional site effects observed at seismological stations on pronounced relief are analyzed. We investigate the ground motion properties calculating horizontal-to-vertical spectral ratios and horizontal polarization of both ambient vibrations and earthquake records using broadband seismograms of the Italian Seismic Network. We find that a subset of 47 stations with pronounced relief, results in a significant (>2) directional amplification of the horizontal component, with a well defined, site-specific direction of motion. However, the horizontal spectral response of sites is not uniform, varying from an isolated (resonant) frequency peak to a broadband amplification, interesting frequency bands as large as 1-10 Hz in many cases. Using the 47 selected stations, we have tried to establish a relation between directional amplification and topography geometry in a 2D-vision, when applicable, through a morphological analysis of the Digital Elevation Model using Geographic Information Systems. The procedure computes the parameters that characterize the geometry of topographic irregularities (size and slope), in combination with a principal component analysis that automatically yields the orientation of the elongated ridges. In seeking a relation between directional amplification and the surface morphology, we have found that it is impossible to fit the variety of observations with a resonant topography model as well as to identify common features in the ground motion behavior for stations with similar topography typologies. We conclude that, rather than the shape of the topography, local structural complexities and details of the near-surface structure must play a predominant role in controlling ground motion properties at sites with pronounced relief.

  17. Rockfall induced seismic signals: case study in Montserrat, Catalonia

    Science.gov (United States)

    Vilajosana, I.; Suriñach, E.; Abellán, A.; Khazaradze, G.; Garcia, D.; Llosa, J.

    2008-08-01

    After a rockfall event, a usual post event survey includes qualitative volume estimation, trajectory mapping and determination of departing zones. However, quantitative measurements are not usually made. Additional relevant quantitative information could be useful in determining the spatial occurrence of rockfall events and help us in quantifying their size. Seismic measurements could be suitable for detection purposes since they are non invasive methods and are relatively inexpensive. Moreover, seismic techniques could provide important information on rockfall size and location of impacts. On 14 February 2007 the Avalanche Group of the University of Barcelona obtained the seismic data generated by an artificially triggered rockfall event at the Montserrat massif (near Barcelona, Spain) carried out in order to purge a slope. Two 3 component seismic stations were deployed in the area about 200 m from the explosion point that triggered the rockfall. Seismic signals and video images were simultaneously obtained. The initial volume of the rockfall was estimated to be 75 m3 by laser scanner data analysis. After the explosion, dozens of boulders ranging from 10-4 to 5 m3 in volume impacted on the ground at different locations. The blocks fell down onto a terrace, 120 m below the release zone. The impact generated a small continuous mass movement composed of a mixture of rocks, sand and dust that ran down the slope and impacted on the road 60 m below. Time, time-frequency evolution and particle motion analysis of the seismic records and seismic energy estimation were performed. The results are as follows: 1 A rockfall event generates seismic signals with specific characteristics in the time domain; 2 the seismic signals generated by the mass movement show a time-frequency evolution different from that of other seismogenic sources (e.g. earthquakes, explosions or a single rock impact). This feature could be used for detection purposes; 3 particle motion plot analysis shows

  18. Romanian earthquakes analysis using BURAR seismic array

    International Nuclear Information System (INIS)

    Borleanu, Felix; Rogozea, Maria; Nica, Daniela; Popescu, Emilia; Popa, Mihaela; Radulian, Mircea

    2008-01-01

    Bucovina seismic array (BURAR) is a medium-aperture array, installed in 2002 in the northern part of Romania (47.61480 N latitude, 25.21680 E longitude, 1150 m altitude), as a result of the cooperation between Air Force Technical Applications Center, USA and National Institute for Earth Physics, Romania. The array consists of ten elements, located in boreholes and distributed over a 5 x 5 km 2 area; nine with short-period vertical sensors and one with a broadband three-component sensor. Since the new station has been operating the earthquake survey of Romania's territory has been significantly improved. Data recorded by BURAR during 01.01.2005 - 12.31.2005 time interval are first processed and analyzed, in order to establish the array detection capability of the local earthquakes, occurred in different Romanian seismic zones. Subsequently a spectral ratios technique was applied in order to determine the calibration relationships for magnitude, using only the information gathered by BURAR station. The spectral ratios are computed relatively to a reference event, considered as representative for each seismic zone. This method has the advantage to eliminate the path effects. The new calibration procedure is tested for the case of Vrancea intermediate-depth earthquakes and proved to be very efficient in constraining the size of these earthquakes. (authors)

  19. Project of a Near-Real-Time Sismo-acoustic Submarine Station for offshore monitoring (NRTSSS)

    Science.gov (United States)

    D'Anna, G.; Calore, D.; Mangano, G.; D'Alessandro, A.; Favali, P.

    2011-12-01

    The INGV seismic network ensures reliable and continuous monitoring of the Italian territory. However, the peculiarity of the Italian peninsula, characterised by an intense offshore geodynamic and seismic activity, requires the extension of the seismic monitoring to the sea. The aim of this project is: - to identify bottleneck is related to the construction, installation and use of underwater seismic station; - to define the most appropriate and low-cost architecture to guarantee the minimum functionality required for a seismic station. In order to obtain reliable seafloor seismic signals integrated to land-based network, the requirements to be fulfill are: - an acceptable coupling with the seabed; - the orientation of the components with respect to the magnetic North and to the verticality; - the correct time stamp of the data; - the data transfer to the land for the integration. Currently, the optimal solution for offshore seismic station is a cable connection to power and real-time data transfer, like the case of Western Ionian Sea cabled observatory, one of the operative node of the EMSO research infrastructure (European Multidisciplinary Seafloor and water column Observatory, http://emso-eu.org). But in the Mediterranean many seismic areas are located a few tens-hundreds of miles from the coast and cabled solutions are not feasible essentially for economic reasons. For this kind of installations EMSO research infrastructure foresees no-cabled solution, that requires a surface buoy deployed in the vicinity seafloor modules.This project plans to develop a surface buoy equipped with autonomous power supply system to power also the seafloor platforms and two-way communication system enabling the data transfer through latest generation of broadband radio communication or satellite link (Fig. 1). All the components of the prototype system are described.

  20. Shallow lunar structure determined from the passive seismic experiment

    International Nuclear Information System (INIS)

    Nakamura, Y.; Dorman, J.; Duennebier, F.; Lammlein, D.; Latham, G.

    1975-01-01

    Data relevant to the shallow structure of the Moon obtained at the Apollo seismic stations are compared with previously published results of the active seismic experiments. It is concluded that the lunar surface is covered by a layer of low seismic velocity (Vsub(p) approximately equal to 100 ms -1 ), which appears to be equivalent to the lunar regolith defined previously by geological observations. This layer is underlain by a zone of distinctly higher seismic velocity at all of the Apollo landing sites. The regolith thicknesses at the Apollo 11, 12, and 15 sites are estimated from the shear-wave resonance to be 4.4, 3.7, and 4.4m, respectively. These thicknesses and those determined at the other Apollo sites by the active seismic experiments appear to be correlated with the age determinations and the abundances of extra-lunar components at the sites. (Auth.)

  1. Stress distribution and seismicity patterns of the 2011 seismic swarm in the Messinia basin, (South-Western Peloponnesus, Greece

    Directory of Open Access Journals (Sweden)

    G. Chouliaras

    2013-01-01

    Full Text Available In this investigation we examine the local stress field and the seismicity patterns associated with the 2011–2012 seismicity swarm in the Messinia basin, south-western Peloponnesus, Greece, using the seismological data of the National Observatory of Athens (NOA. During this swarm more than 2000 events were recorded in a 12 month period by the Hellenic Unified Seismological Network (HUSN and also by the additional local installation of four portable broadband seismographic stations by NOA.

    The results indicate a Gaussian distribution of swarm activity and the development of a seismicity cluster in a pre-existing seismic gap within the Messinia basin. Centroid Moment Tensor solutions demonstrate a normal fault trending northwest–southeast and dipping to the southwest primarily due to an extensional stress field. During this seismicity swarm an epicentre migration of the three largest shocks is observed, from one end of the rupture zone in the north-western part of the cluster, towards the other edge of the rupture in the south-eastern part of the cluster. This migration is found to follow the Coulomb failure criterion that predicts the advancement and retardation of the stress field and the patterns of increases and decreases of the seismicity rate (b-value of the frequency–magnitude relation.

  2. Long-term changes of the glacial seismicity: case study from Spitsbergen

    Science.gov (United States)

    Gajek, Wojciech; Trojanowski, Jacek; Malinowski, Michał

    2016-04-01

    Changes in global temperature balance have proved to have a major impact on the cryosphere, and therefore withdrawing glaciers are the symbol of the warming climate. Our study focuses on year-to-year changes in glacier-generated seismicity. We have processed 7-year long continuous seismological data recorded by the HSP broadband station located in the proximity of Hansbreen glacier (Hornsund, southern Spitsbergen), obtaining seismic activity distribution between 2008 and 2014. We developed a new fuzzy logic algorithm to distinguish between glacier- and non-glacier-origin events. The algorithm takes into account the frequency of seismic signal and the energy flow in certain time interval. Our research has revealed that the number of detected glacier-origin events over last two years has doubled. Annual events distribution correlates well with temperature and precipitation curves, illustrating characteristic yearlong behaviour of glacier seismic activity. To further support our observations, we have analysed 5-year long distribution of glacier-origin tremors detected in the vicinity of the Kronebreen glacier using KBS broadband station located in Ny-Ålesund (western Spitsbergen). We observe a steady increase in the number of detected events. detected each year, however not as significant as for Hornsund dataset.

  3. VFM Discrimination Results from a Ten Station Network

    Science.gov (United States)

    1980-07-01

    Chiang Mai , Thailand (CHTO) from a presumed explosion in eastern Kazakhstan .................... 24 5. Seismogram written at Tatalina, Alaska, for the same...results for the station located at Chiang Mai , Thailand (CHTO) ... .......... . 55 15c. VFM results for the station located at Zongo Valley, Bolivia...seismogram written at the Seismic Research Observatory (SRO) in Chiang Mai , Thailand (CHTO) from a presumed explosion in eastern Kazakhstan. The top is the

  4. Comparison of Omega-2 and Omega-3 calibration explosions basing on regional seismic data

    International Nuclear Information System (INIS)

    Mikhajlova, N.N.; Sokolova, I.N.

    2001-01-01

    Comparison of different parameters of seismic records of Omega-2 and Omega-3 calibration explosions was performed. It was shown that despite the equal charge the level of seismic oscillations was lower during the Omega-3 explosion than during Omega-2. Spectral composition, polarization of oscillations, wave picture is identical at a given station for both explosions. Assumptions were made on the reason of such difference in seismic effect. (author)

  5. Seismicity of the Tihamat-Asir region, Kingdom of Saudi Arabia

    Science.gov (United States)

    Merghelani, Habib M.

    1979-01-01

    Knowledge of the seismicity of the west coast of Saudi Arabia is vitally important to the Kingdom. The eastern margin of the Red Sea, which includes all of the west coast of Saudi Arabia, is possibly cut by transform faults that may be capable of producing earthquakes large enough to cause damage in the heavily populated areas or in the industrial complexes under construction. Prior to this study, there were no seismic stations in Saudi Arabia and no studies of microearthquake activity. It was generally assumed that there were no active faults along the west coast. During the period 20 January to 22 February, 1978, five portable seismic stations were deployed in the Tihamat Asir in the southwest part of the country. A significant level of microearthquake activity was detected at a location that approximately coincides with the landward extension of the proposed transform fault. The recording of these earthquakes demonstrates that there are active faults at this location, probably associated with the currently active Red Sea tectonic system. The practical significance of these earthquakes cannot be evaluated from the few data available, and further studies should be undertaken to determine if there are significant seismic hazards along the west coast of Saudi Arabia. 

  6. Evaluation of the new infrastructure for French Permanent Broadband Stations in Auvergne (France).

    Science.gov (United States)

    Douchain, J. M.; Regis, E.; Battaglia, J.; Vergne, J.

    2017-12-01

    French seismologic and geodetic network (RESIF) is a national equipment for the observation and understanding of the solid Earth. It is an instrument aimed at acquiring new top-quality data for disciplines like seismology, geodesy and gravimetry to advance the understanding of the dynamics of our planet. The seismology component of RESIF, with its homogeneous coverage of the territory, will allow better localisation and characterisation of seismic activityover a wide range of magnitudes as well as provide high quality data for research The Auvergne Seismic Network (ASN) manages seismic stations in the center of france since the beginning of the 80's and continuously ugrades them. Nowadays, 21 stations (velocimeters and accelerometers) are deployed to monitor the Massif Central seismic activity. In the future, the ASN will run 15 broadband stations that will be part of RESIF network. Six of theses sites already have former generation instrumentation (short period sensors buried in the ground, low dynamic) but others are completely new. In june 2017, 4 permanent seismic stations have been upgraded to the new standard installation type for open environment. The chozen infrastructure is a 5 meter drilling equiped with a posthole broadband sensor. Prior to these final installations, on each site, Trillium 120 PA have been installed for 2 temporary experiments. The first one consisted of a direct burial installations at about 80 centimeters depth and lasted for 1 or 2 months. The second dataset was recorded in shallow seismic vaults, during 6 months.In this study, we compare, for each site, data recorded with the 3 configurations in order to evaluate the profits of the new RESIF installations. For this purpose, we compare the probability density fonctions to evaluate noise levels, as well as sprectrograms and hourly detection number. Our results show that the installation of sensors in drillings greatly improves the quality of data at low and high frequencies.

  7. A seismic network to investigate the sedimentary hosted hydrothermal Lusi system

    Science.gov (United States)

    Javad Fallahi, Mohammad; Mazzini, Adriano; Lupi, Matteo; Obermann, Anne; Karyono, Karyono

    2016-04-01

    The 29th of May 2006 marked the beginning of the sedimentary hosted hydrothermal Lusi system. During the last 10 years we witnessed numerous alterations of the Lusi system behavior that coincide with the frequent seismic and volcanic activity occurring in the region. In order to monitor the effect that the seismicity and the activity of the volcanic arc have on Lusi, we deployed a ad hoc seismic network. This temporary network consist of 10 broadband and 21 short period stations and is currently operating around the Arjuno-Welirang volcanic complex, along the Watukosek fault system and around Lusi, in the East Java basin since January 2015. We exploit this dataset to investigate surface wave and shear wave velocity structure of the upper-crust beneath the Arjuno-Welirang-Lusi complex in the framework of the Lusi Lab project (ERC grant n° 308126). Rayleigh and Love waves travelling between each station-pair are extracted by cross-correlating long time series of ambient noise data recorded at the stations. Group and phase velocity dispersion curves are obtained by time-frequency analysis of cross-correlation functions, and are tomographically inverted to provide 2D velocity maps corresponding to different sampling depths. 3D shear wave velocity structure is then acquired by inverting the group velocity maps.

  8. Seismicity and seismic hazard in Sabah, East Malaysia from earthquake and geodetic data

    Science.gov (United States)

    Gilligan, A.; Rawlinson, N.; Tongkul, F.; Stephenson, R.

    2017-12-01

    While the levels of seismicity are low in most of Malaysia, the state of Sabah in northern Borneo has moderate levels of seismicity. Notable earthquakes in the region include the 1976 M6.2 Lahad Datu earthquake and the 2015 M6 Ranau earthquake. The recent Ranau earthquake resulted in the deaths of 18 people on Mt Kinabalu, an estimated 100 million RM ( US$23 million) damage to buildings, roads, and infrastructure from shaking, and flooding, reduced water quality, and damage to farms from landslides. Over the last 40 years the population of Sabah has increased to over four times what it was in 1976, yet seismic hazard in Sabah remains poorly understood. Using seismic and geodetic data we hope to better quantify the hazards posed by earthquakes in Sabah, and thus help to minimize risk. In order to do this we need to know about the locations of earthquakes, types of earthquakes that occur, and faults that are generating them. We use data from 15 MetMalaysia seismic stations currently operating in Sabah to develop a region-specific velocity model from receiver functions and a pre-existing surface wave model. We use this new velocity model to (re)locate earthquakes that occurred in Sabah from 2005-2016, including a large number of aftershocks from the 2015 Ranau earthquake. We use a probabilistic nonlinear earthquake location program to locate the earthquakes and then refine their relative locations using a double difference method. The recorded waveforms are further used to obtain moment tensor solutions for these earthquakes. Earthquake locations and moment tensor solutions are then compared with the locations of faults throughout Sabah. Faults are identified from high-resolution IFSAR images and subsequent fieldwork, with a particular focus on the Lahad Datau and Ranau areas. Used together, these seismic and geodetic data can help us to develop a new seismic hazard model for Sabah, as well as aiding in the delivery of outreach activities regarding seismic hazard

  9. Seismic monitoring of the Yucca Mountain facility

    International Nuclear Information System (INIS)

    Garbin, H.D.; Herrington, P.B.; Kromer, R.P.

    1997-01-01

    Questions have arisen regarding the applicability of seismic sensors to detect mining (re-entry) with a tunnel boring machine (TBM). Unlike cut and blast techniques of mining which produce impulsive seismic signals, the TBM produces seismic signals which are of long duration. (There are well established techniques available for detecting and locating the sources of the impulsive signals.) The Yucca Mountain repository offered an opportunity to perform field evaluations of the capabilities of seismic sensors because during much of 1996, mining there was progressing with the use of a TBM. During the mining of the repository's southern branch, an effort was designed to evaluate whether the TBM could be detected, identified and located using seismic sensors. Three data acquisition stations were established in the Yucca Mountain area to monitor the TBM activity. A ratio of short term average to long term average algorithm was developed for use in signal detection based on the characteristics shown in the time series. For location of the source of detected signals, FK analysis was used on the array data to estimate back azimuths. The back azimuth from the 3 component system was estimated from the horizontal components. Unique features in the timing of the seismic signal were used to identify the source as the TBM

  10. A Case Study of Geologic Hazards Affecting School Buildings: Evaluating Seismic Structural Vulnerability and Landslide Hazards at Schools in Aizawl, India

    Science.gov (United States)

    Perley, M. M.; Guo, J.

    2016-12-01

    India's National School Safety Program (NSSP) aims to assess all government schools in earthquake prone regions of the country. To supplement the Mizoram State Government's recent survey of 141 government schools, we screened an additional 16 private and 4 government schools for structural vulnerabilities due to earthquakes, as well as landslide hazards, in Mizoram's capital of Aizawl. We developed a geomorphologically derived landslide susceptibility matrix, which was cross-checked with Aizawl Municipal Corporation's landslide hazard map (provided by Lettis Consultants International), to determine the geologic hazards at each school. Our research indicates that only 7% of the 22 assessed school buildings are located within low landslide hazard zones; 64% of the school buildings, with approximately 9,500 students, are located within very high or high landslide hazard zones. Rapid Visual Screening (RVS) was used to determine the structural earthquake vulnerability of each school building. RVS is an initial vulnerability assessment procedure used to inventory and rank buildings that may be hazardous during an earthquake. Our study indicates that all of the 22 assessed school buildings have a damageability rating of Grade 3 or higher on the 5-grade EMS scale, suggesting a significant vulnerability and potential for damage in buildings, ranging from widespread cracking of columns and beam column joints to collapse. Additionally, 86% of the schools we visited had reinforced concrete buildings constructed before Aizawl's building regulations were passed in 2007, which can be assumed to lack appropriate seismic reinforcement. Using our findings, we will give recommendations to the Government of Mizoram to prevent unnecessary loss of life by minimizing each school's landslide risk and ensuring schools are earthquake-resistant.

  11. A national seismographic network for assessing seismic hazards

    International Nuclear Information System (INIS)

    Masse, R.P.; Murphy, A.J.

    1989-01-01

    To access the seismic hazard of a region and to establish the design and construction criteria for critical facilities such as nuclear power plants, detailed information is required on the frequency of occurrence, geographical distribution, magnitude, and energy spectra of earthquakes. Also important is information on the frequency-dependent attenuation of seismic waves. This information can all be obtained from data recorded by networks of seismograph stations. A new seismograph network for the US which takes advantage of advances in technology is currently under development. This network is the US National Seismograph Network (USNSN). The USNSN is a cooperative effort between the National Earthquake Information Center (NEIC) of the US Geological survey and the Nuclear Regulatory Commission. The USNSN will be installed and operated by the NEIC. The network will consist of approximately 150 seismograph stations distributed across the lower 48 states and across Alaska, Hawaii, Puerto Rico, and the Virgin Islands. The design goal for the network is the on-scale recording by at least five well-distributed stations of any event of magnitude 2.5 or larger in the continental US, Hawaii, and Puerto Rico, and of any event of magnitude 3.5 or larger in Alaska. The rapid access to all USNSN data will be provided by the NEIC. This will be accomplished both via a dial-up capability to the event waveform data base and by satellite transmission in a broadcast mode. All earthquake data will also be distributed on compact disk with read only memory (CD-ROM) to all institutions having an interest in the seismic data

  12. Optimizing Seismic Monitoring Networks for EGS and Conventional Geothermal Projects

    Science.gov (United States)

    Kraft, Toni; Herrmann, Marcus; Bethmann, Falko; Stefan, Wiemer

    2013-04-01

    location problem. Optimization for additional criteria (e.g., focal mechanism determination or installation costs) can be included. We consider a 3D seismic velocity model, an European ambient seismic noise model derived from high-resolution land-use data, and existing seismic stations in the vicinity of the geotechnical site. Additionally, we account for the attenuation of the seismic signal with travel time and ambient seismic noise with depth to be able to correctly deal with borehole station networks. Using this algorithm we are able to find the optimal geometry and size of the seismic monitoring network that meets the predefined application-oriented performance criteria. This talk will focus on optimal network geometries for deep geothermal projects of the EGS and hydrothermal type, and discuss the requirements for basic seismic surveillance and high-resolution reservoir monitoring and characterization.

  13. Actions at Kashiwazaki Kariwa Nuclear Power Station after the Niigataken Chuetsu-oki earthquake

    International Nuclear Information System (INIS)

    Orita, Shuichi

    2009-01-01

    'The Niigataken Chuetsu-oki Earthquake in 2007' occurred on July 16, 2007, and seismic motions beyond those of the design basis earthquake were recorded at Kashiwazaki Kariwa nuclear power station located near the epicenter. After the earthquake, inspections and seismic response analyses have been being performed to grasp seismic induced impacts on structures, systems and components (SSCs). In addition, re-definition of design basis earthquake, upgrading, management against disasters have been also being conducted. (author)

  14. Seismic instrumentation plan for the Hawaiian Volcano Observatory

    Science.gov (United States)

    Thelen, Weston A.

    2014-01-01

    The seismic network operated by the U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) is the main source of authoritative data for reporting earthquakes in the State of Hawaii, including those that occur on the State’s six active volcanoes (Kīlauea, Mauna Loa, Hualālai, Mauna Kea, Haleakalā, Lō‘ihi). Of these volcanoes, Kīlauea and Mauna Loa are considered “very high threat” in a report on the rationale for a National Volcanic Early Warning System (NVEWS) (Ewert and others, 2005). This seismic instrumentation plan assesses the current state of HVO’s seismic network with respect to the State’s active volcanoes and calculates the number of stations that are needed to upgrade the current network to provide a seismic early warning capability for forecasting volcanic activity. Further, the report provides proposed priorities for upgrading the seismic network and a cost assessment for both the installation costs and maintenance costs of the improved network that are required to fully realize the potential of the early warning system.

  15. Discriminating Induced-Microearthquakes Using New Seismic Features

    Science.gov (United States)

    Mousavi, S. M.; Horton, S.

    2016-12-01

    We studied characteristics of induced-microearthquakes on the basis of the waveforms recorded on a limited number of surface receivers using machine-learning techniques. Forty features in the time, frequency, and time-frequency domains were measured on each waveform, and several techniques such as correlation-based feature selection, Artificial Neural Networks (ANNs), Logistic Regression (LR) and X-mean were used as research tools to explore the relationship between these seismic features and source parameters. The results show that spectral features have the highest correlation to source depth. Two new measurements developed as seismic features for this study, spectral centroids and 2D cross-correlations in the time-frequency domain, performed better than the common seismic measurements. These features can be used by machine learning techniques for efficient automatic classification of low energy signals recorded at one or more seismic stations. We applied the technique to 440 microearthquakes-1.7Reference: Mousavi, S.M., S.P. Horton, C. A. Langston, B. Samei, (2016) Seismic features and automatic discrimination of deep and shallow induced-microearthquakes using neural network and logistic regression, Geophys. J. Int. doi: 10.1093/gji/ggw258.

  16. Assessment of the impact of degraded shear wall stiffnesses on seismic plant risk and seismic design loads

    International Nuclear Information System (INIS)

    Klamerus, E.W.; Bohn, M.P.; Johnson, J.J.; Asfura, A.P.; Doyle, D.J.

    1994-02-01

    Test results sponsored by the USNRC have shown that reinforced shear wall (Seismic Category I) structures exhibit stiffnesses and natural frequencies which are smaller than those calculated in the design process. The USNRC has sponsored Sandia National Labs to perform an evaluation of the effects of the reduced frequencies on several existing seismic PRAs in order to determine the seismic risk implications inherent in these test results. This report presents the results for the re-evaluation of the seismic risk for three nuclear power plants: the Peach Bottom Atomic Power Station, the Zion Nuclear Power Plant, and Arkansas Nuclear One -- Unit 1 (ANO-1). Increases in core damage frequencies for seismic initiated events at Peach Bottom were 25 to 30 percent (depending on whether LLNL or EPRI hazard curves were used). At the ANO-1 site, the corresponding increases in plant risk were 10 percent (for each set of hazard curves). Finally, at Zion, there was essentially no change in the computed core damage frequency when the reduction in shear wall stiffness was included. In addition, an evaluation of deterministic ''design-like'' structural dynamic calculations with and without the shear stiffness reductions was made. Deterministic loads calculated for these two cases typically increased on the order of 10 to 20 percent for the affected structures

  17. The Ongoing Addition of Infrasound Sensors and the Flexette Wind-Noise Reducing System to Global Seismic Network Stations Operated by Project IDA

    Science.gov (United States)

    Ebeling, C. W.; Coon, C.

    2017-12-01

    Infrasound sensors are now being installed at Global Seismic Network (GSN) stations meeting certain infrastructure criteria. Manufactured by Hyperion Technology Group, Inc., these instruments (model IFS-3312) have a nominal sensitivity of 140 mV/Pa (at 1 Hz), a full-scale range of ±100 Pa, and a dynamic range of 120 dB. Low power consumption (750 mW at 12 VDC) and small size (153 mm x 178 mm) ease incorporation into the mix of existing GSN instrumentation. The accompanying flexible rosette ("Flexette") acoustic wind-noise reducing system, designed by Project IDA (International Deployment of Accelerometers-IDA), optimally includes 24 inlets, 4 secondary manifolds, and a single primary manifold. Each secondary manifold is connected to 6 inlets and to the primary manifold by 10-ft air hoses, thus eliminating stresses and the greater potential for leaks associated with the use of pipe. While the main design goal was to maximize the reduction of acoustic wind-noise over the widest range of wind speeds possible, consideration of additional criteria resulted in a Flexette base design easily tailored to meet individual station constraints and restrictions, made up of inexpensive (total cost Marshall Islands), in August 2017. During the next 6 months infrasound capability will be extended to IDA GSN stations BORG (Borganes, Iceland), EFI (Mount Kent, East Falkland Islands), and SACV (Santiago Island, Cape Verde).As with other data from GSN stations, real-time infrasound data are freely available from the Incorporated Research Institutions for Seismology-Data Management Center (IRIS-DMC).

  18. 6C polarization analysis - seismic direction finding in coherent noise, automated event identification, and wavefield separation

    Science.gov (United States)

    Schmelzbach, C.; Sollberger, D.; Greenhalgh, S.; Van Renterghem, C.; Robertsson, J. O. A.

    2017-12-01

    Polarization analysis of standard three-component (3C) seismic data is an established tool to determine the propagation directions of seismic waves recorded by a single station. A major limitation of seismic direction finding methods using 3C recordings, however, is that a correct propagation-direction determination is only possible if the wave mode is known. Furthermore, 3C polarization analysis techniques break down in the presence of coherent noise (i.e., when more than one event is present in the analysis time window). Recent advances in sensor technology (e.g., fibre-optical, magnetohydrodynamic angular rate sensors, and ring laser gyroscopes) have made it possible to accurately measure all three components of rotational ground motion exhibited by seismic waves, in addition to the conventionally recorded three components of translational motion. Here, we present an extension of the theory of single station 3C polarization analysis to six-component (6C) recordings of collocated translational and rotational ground motions. We demonstrate that the information contained in rotation measurements can help to overcome some of the main limitations of standard 3C seismic direction finding, such as handling multiple arrivals simultaneously. We show that the 6C polarisation of elastic waves measured at the Earth's free surface does not only depend on the seismic wave type and propagation direction, but also on the local P- and S-wave velocities just beneath the recording station. Using an adaptation of the multiple signal classification algorithm (MUSIC), we demonstrate how seismic events can univocally be identified and characterized in terms of their wave type. Furthermore, we show how the local velocities can be inferred from single-station 6C data, in addition to the direction angles (inclination and azimuth) of seismic arrivals. A major benefit of our proposed 6C method is that it also allows the accurate recovery of the wave type, propagation directions, and phase

  19. How prepared were the Puerto Rico Seismic Network sites for the arrival of Hurricane Maria? Lessons learned on communications, power and infrastructure.

    Science.gov (United States)

    Vanacore, E. A.; Lopez, A. M.; Huerfano, V.; Lugo, J.; Baez-Sanchez, G.

    2017-12-01

    For exactly 85 years the island of Puerto Rico in the northeastern Caribbean was spared from catastrophic category 4 hurricane winds. Then Hurricane Maria arrived on September 20, 2017 with maximum sustained winds of up to 155 mph. The eye of the hurricane crossed the island from southeast to northwest in eight hours leaving almost a meter of rainfall on its path. Sustained winds, gusts and precipitation were most certainly going to affect the seismic and geodetic equipment the Puerto Rico Seismic Network (PRSN) use for locating earthquakes in the region. PRSN relies on 35 seismic stations (velocity and strong-motion) to characterize the seismic behavior of the island and 15 geodetic (GNSS) stations to determine crustal deformation of the Puerto Rico - Virgin Islands microplate. PRSN stations have been designed to withstand earthquakes. However, the equipment suffered considerable damage due to the strong winds especially station communication towers. This coupled with catastrophic damage to the telecommunication and power grids of the island had severe effects on the network. Additionally, the level of devastation was such that it hampered the ability of PRSN staff to visit the sites for assessment and repair. Here we present the effects of category 4 hurricane had on our seismic and geodetic sites, examine the susceptibility of the PRSN stations' power and communications, and discuss future plans to recuperate and improve station resiliency for future catastrophic events. These lessons learned hopefully will help harden sites of networks, agencies and/or institutions that rely on similar infrastructure.

  20. Application of a simplified seismic risk methodology to the La Salle County Station Unit 2 BWR

    International Nuclear Information System (INIS)

    Lappa, D.A.; Wells, J.E.

    1986-01-01

    It is important to bear in mind that no risk assessment of any U.S. nuclear power plant can be interpreted to be generally representative of more than a handful of other U.S. plants. Variations in factors ranging from plant age and operating experience to NRC licensing requirements and design guidelines have led to a wide diversity of power plants in the United States. Except for a few combinations of plants of comparable design and vintage, the extension of plant-specific results to other nuclear power plants should only be done with considerable trepidation. This situation is worsened for a seismic PRA because of the variability in the seismic hazard from site to site. In the case of this study, it would be a mistake to infer that all BWRs are sufficiently resistant to earthquakes because of the generally low seismic failure probabilities at La Salle. Unless those BWRs had similar site characteristics and were of a similar design and vintage as La Salle, no immediate extension of this study's results would be appropriate. With these thoughts in mind, we turn our attention to one of the questions which the La Salle seismic PRA is supposed to address, namely, the comparable seismic vulnerability of BWRs and PWRs. The La Salle study has provided us with some insight to the seismic risk at a particular BWR. This information may or may not be useful to understanding the seismic vulnerability of other BWRs

  1. Results from an onshore/offshore seismic transect of southern Taiwan

    Science.gov (United States)

    McIntosh, K. D.; van Avendonk, H. J.; Wu, F. T.; Okaya, D. A.; Wang, C.

    2010-12-01

    The TAIGER project is a large research program focused on the processes and dynamics of arc-continent collision. As part of the project we recorded marine and onshore-offshore seismic data in summer 2009 using the R/V Langseth, ocean bottom seismometers (OBS) from the U.S. OBS instrument pool and from National Taiwan Ocean University, and land instruments from PASSCAL and Taiwan. Because the region from north of Luzon to northern Taiwan encompasses a multiphase transition from oceanic subduction to arc-continent collision, the TAIGER data sets along with state of the art geodynamic modeling are starting to provide fundamental insights into this complex process. This presentation focuses on initial results of an onshore/offshore seismic transect across southern Taiwan. One of the keys to success in studying the arc-continent collision in Taiwan is to document the crustal structure in the developing collision zone of southern Taiwan. This is where we hope to be able to view the transition from what looks like subduction to the south, to the more complex collision zone to the north. In this area we acquired an ~east-west seismic transect using 4 OBSs west of Taiwan, 40 portable land seismometers crossing the island from near Kaohsiung (W) to near Taitung (E) , and 14 OBSs east of Taiwan. As expected, data quality is extremely variable due to local geology at each station and, for land instruments, the level of cultural noise near each station. In fact, some of the land stations show no usable signals from seismic source pulses either east or west of Taiwan. However, other more fortuitously located instrument show clear arrivals at offsets of up to 280 km. As expected, all the best stations are located in mountainous areas where there is a minimum of unconsolidated material and less cultural noise. The land station data include primarily Pg and Pn arrivals, while the OBS data include a full range of reflected and refracted arrivals. The marine wide-angle data will also

  2. Modeling the Excitation of Seismic Waves by the Joplin Tornado

    Science.gov (United States)

    Valovcin, Anne; Tanimoto, Toshiro

    2017-10-01

    Tornadoes generate seismic signals when they contact the ground. Here we examine the signals excited by the Joplin tornado, which passed within 2 km of a station in the Earthscope Transportable Array. We model the tornado-generated vertical seismic signal at low frequencies (0.01-0.03 Hz) and solve for the strength of the seismic source. The resulting source amplitude is largest when the tornado was reported to be strongest (EF 4-5), and the amplitude is smallest when the tornado was weak (EF 0-2). A further understanding of the relationship between source amplitude and tornado intensity could open up new ways to study tornadoes from the ground.

  3. Local seismic network at the Olkiluoto site. Annual report for 2009

    International Nuclear Information System (INIS)

    Saari, J.; Malm, M.

    2010-06-01

    Excavation of the underground characterisation facility (the ONKALO) started in 2004. Before that, in February 2002, Posiva Oy established a local seismic network of six stations on the island of Olkiluoto. After that the number of seismic stations has increased gradually. In 2009 Posiva's seismic network consists of 14 seismic stations and 19 triaxial sensors. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas. The larger target area, called seismic semiregional area, covers the Olkiluoto Island and its surroundings. The purpose is to monitor explosions and tectonic earthquakes in regional scale inside that area. The smaller target area is called the seismic ONKALO block, which is a 2 km *2 km *2 km cube surrounding the ONKALO. It is assumed that all the expected excavation induced events occur within this volume. At the moment the seismic ONKALO block includes ten seismic stations. An additional task of monitoring is related to safeguarding of the ONKALO. This report gives the results of microseismic monitoring during 2009. Also the changes in the structure and the operation procedure of the network are described. The upgrades in 2009 are limited to the processing, interpretation and reporting practices. The latest upgrades of the equipment were done in November 2008. The final technical tuning and tests related to the upgrade were done in the beginning of 2009. The network has operated continuously in 2009. Altogether 1256 events have been located in the Olkiluoto area, in reported time period. Most of them (1161) are explosions occurred inside the seismic semi-regional area and especially inside the seismic ONKALO block (1135 events). The magnitudes of the observed events inside the semi-regional area range from ML = -1.5 to ML = 1.6 (ML = magnitude in local Richter's scale). Most of them are explosions. Two

  4. Seismic evaluation of non-seismically designed existing Magnox nuclear power plants

    International Nuclear Information System (INIS)

    Kunar, R.R.

    1984-01-01

    The philosophy and method adopted for the seismic assessment of three existing Magnox nuclear stations in the United Kingdom are presented in this paper. The plants were not seismically designed. The particular procedures that were applied were tailored to suit the difficulties of lack of data which is somewhat inevitable for plants designed and built about 25 to 30 years ago. Special procedures included on-site testing with a portable shake table, low vibration testing using a structural dynamics analyser, and on-site inspections. The low vibration testing was most invaluable in detecting differences between 'as-built' conditions and the engineering drawings. From the point of view of economics, this was more effective than conducting full structural surveys to determine the as-built conditions. The testing results also provided confidence in the answers from numerical models. The philosophy adopted for the Magnox reactors in the seismic assessment was to determine what peak ground accelerations the sites can sustain and then evaluate the chances of exceeding the ground accelerations over the remaining lifetime of the plants. The peak ground acceleration for each site was determined on the basis of the criteria of safe shutdown and prevention of significant off-site radiological exposure

  5. Integration of onshore and offshore seismological data to study the seismicity of the Calabrian Region

    Science.gov (United States)

    D'Alessandro, Antonino; Guerra, Ignazio; D'Anna, Giuseppe; Gervasi, Anna; Harabaglia, Paolo; Luzio, Dario; Stellato, Gilda

    2014-05-01

    The Pollino Massif marks the transition from the Southern Appenninic to the Calabrian Arc. On the western side it is characterized by a moderately sized seismicity (about 9 M > 4 events in the last 50 years), well documented in the last 400 years. The moment tensor solutions available in this area yields, mainly, normal faults with coherent Southern Appeninic trend. This remains true also for the events that are localized on the calabrian side of Pollino, South of the massif. In most of the Sibari plane, seismic activity is very scarce, while it is again rather marked on its southeastern corner, both onshore and offshore. The above observations point to the perspective that the stress field of a vast portion of Northern Calabria still resembles that of the Southern Appenines. In this frame, it becomes important to investigate the offshore seismicity of the Sibari Gulf and the deformation pattern within the Sibari Plane. The latter might function as a hinge to transfer the deformation of the extensional fault system in the Pollino area to a different offshore fault system. Since return times of larger events might be very long, we need to investigate the true seismic potential of the offshore faults and to verify whether they are truly strike slip or if they could involve relevant thrust or normal components, that would add to the risk that of potentially associated tsunamis. Despite their importance in the understanding of the seismotectonic processes taking place in the Southern Appenninic - Calabrian Arc border and surrounding areas, the seismicity and the seismogenic volumes of the Sibari Gulf until now has not been well characterized due to the lack of offshore seismic stations. The seismicity of the Calabrian is monitored by the Italian National Seismic Network (INSN) managed by Istituto Nazionale di Geofisica e Vulcanologia and by the Calabrian Regional Seismic Network (CRSN) managed by the University of Calabria. Both the network comprise only on

  6. The Lusi seismic experiment: An initial study to understand the effect of seismic activity to Lusi

    Energy Technology Data Exchange (ETDEWEB)

    Karyono, E-mail: karyonosu@gmail.com [Agency for Meteorology, Climatology and Geophysics (BMKG), Jakarta (Indonesia); OSLO University (Norway); Padjadjaran University (UNPAD), Bandung (Indonesia); Mazzini, Adriano; Sugiharto, Anton [OSLO University (Norway); Lupi, Matteo [ETH Zurich (Switzerland); Syafri, Ildrem [Padjadjaran University (UNPAD), Bandung (Indonesia); Masturyono,; Rudiyanto, Ariska; Pranata, Bayu; Muzli,; Widodo, Handi Sulistyo; Sudrajat, Ajat [Agency for Meteorology, Climatology and Geophysics (BMKG), Jakarta (Indonesia)

    2015-04-24

    The spectacular Lumpur Sidoarjo (Lusi) eruption started in northeast Java on the 29 of May 2006 following a M6.3 earthquake striking the island [1,2]. Initially, several gas and mud eruption sites appeared along the reactivated strike-slip Watukosek fault system [3] and within weeks several villages were submerged by boiling mud. The most prominent eruption site was named Lusi. The Lusi seismic experiment is a project aims to begin a detailed study of seismicity around the Lusi area. In this initial phase we deploy 30 seismometers strategically distributed in the area around Lusi and along the Watukosek fault zone that stretches between Lusi and the Arjuno Welirang (AW) complex. The purpose of the initial monitoring is to conduct a preliminary seismic campaign aiming to identify the occurrence and the location of local seismic events in east Java particularly beneath Lusi.This network will locate small event that may not be captured by the existing BMKG network. It will be crucial to design the second phase of the seismic experiment that will consist of a local earthquake tomography of the Lusi-AW region and spatial and temporal variations of vp/vs ratios. The goal of this study is to understand how the seismicity occurring along the Sunda subduction zone affects to the behavior of the Lusi eruption. Our study will also provide a large dataset for a qualitative analysis of earthquake triggering studies, earthquake-volcano and earthquake-earthquake interactions. In this study, we will extract Green’s functions from ambient seismic noise data in order to image the shallow subsurface structure beneath LUSI area. The waveform cross-correlation technique will be apply to all of recordings of ambient seismic noise at 30 seismographic stations around the LUSI area. We use the dispersive behaviour of the retrieved Rayleigh waves to infer velocity structures in the shallow subsurface.

  7. Internet-Based Solutions for a Secure and Efficient Seismic Network

    Science.gov (United States)

    Bhadha, R.; Black, M.; Bruton, C.; Hauksson, E.; Stubailo, I.; Watkins, M.; Alvarez, M.; Thomas, V.

    2017-12-01

    The Southern California Seismic Network (SCSN), operated by Caltech and USGS, leverages modern Internet-based computing technologies to provide timely earthquake early warning for damage reduction, event notification, ShakeMap, and other data products. Here we present recent and ongoing innovations in telemetry, security, cloud computing, virtualization, and data analysis that have allowed us to develop a network that runs securely and efficiently.Earthquake early warning systems must process seismic data within seconds of being recorded, and SCSN maintains a robust and resilient network of more than 350 digital strong motion and broadband seismic stations to achieve this goal. We have continued to improve the path diversity and fault tolerance within our network, and have also developed new tools for latency monitoring and archiving.Cyberattacks are in the news almost daily, and with most of our seismic data streams running over the Internet, it is only a matter of time before SCSN is targeted. To ensure system integrity and availability across our network, we have implemented strong security, including encryption and Virtual Private Networks (VPNs).SCSN operates its own data center at Caltech, but we have also installed real-time servers on Amazon Web Services (AWS), to provide an additional level of redundancy, and eventually to allow full off-site operations continuity for our network. Our AWS systems receive data from Caltech-based import servers and directly from field locations, and are able to process the seismic data, calculate earthquake locations and magnitudes, and distribute earthquake alerts, directly from the cloud.We have also begun a virtualization project at our Caltech data center, allowing us to serve data from Virtual Machines (VMs), making efficient use of high-performance hardware and increasing flexibility and scalability of our data processing systems.Finally, we have developed new monitoring of station average noise levels at most stations

  8. Annual Hanford Seismic Report for Fiscal Year 2008

    Energy Technology Data Exchange (ETDEWEB)

    Rohay, Alan C.; Sweeney, Mark D.; Hartshorn, Donald C.; Clayton, Ray E.; Devary, Joseph L.

    2008-12-29

    119 degrees and 120 degrees west longitude). The event was not reported as being felt on the Hanford Site or causing any damage and was communicated to the Pacific Northwest National Laboratory Operations Center per HSAP communi¬cations procedures. The event is not considered to be significant with regard to site safety and not unprecedented given the site’s seismic history. The Hanford strong motion accelerometer (SMA) stations at the 200 East Area, 300 Area, and 400 Area were triggered by the May 18 event. The maximum acceleration recorded at the SMA stations (0.17% at the 300 Area) was 12 times smaller than the reportable action level (2% g) for Hanford Site facilities.

  9. Empirical Ground Motion Characterization of Induced Seismicity in Alberta and Oklahoma

    Science.gov (United States)

    Novakovic, M.; Atkinson, G. M.; Assatourians, K.

    2017-12-01

    We develop empirical ground-motion prediction equations (GMPEs) for ground motions from induced earthquakes in Alberta and Oklahoma following the stochastic-model-based method of Atkinson et al. (2015 BSSA). The Oklahoma ground-motion database is compiled from over 13,000 small to moderate seismic events (M 1 to 5.8) recorded at 1600 seismic stations, at distances from 1 to 750 km. The Alberta database is compiled from over 200 small to moderate seismic events (M 1 to 4.2) recorded at 50 regional stations, at distances from 30 to 500 km. A generalized inversion is used to solve for regional source, attenuation and site parameters. The obtained parameters describe the regional attenuation, stress parameter and site amplification. Resolving these parameters allows for the derivation of regionally-calibrated GMPEs that can be used to compare ground motion observations between waste water injection (Oklahoma) and hydraulic fracture induced events (Alberta), and further compare induced observations with ground motions resulting from natural sources (California, NGAWest2). The derived GMPEs have applications for the evaluation of hazards from induced seismicity and can be used to track amplitudes across the regions in real time, which is useful for ground-motion-based alerting systems and traffic light protocols.

  10. Seismic Investigations of the Crust and Upper Mantle Structure in Antarctica and Madagascar

    Science.gov (United States)

    Ramirez, Cristo

    In the three studies that form this dissertation, seismic data from Antarctica and Madagascar have been analyzed to obtain new insights into crustal structure and mantle flow. Until recently, there have been little seismic data available from these areas for interrogating Earth structure and processes. In Antarctica, I analyzed datasets from temporary deployments of broadband seismic stations in both East and West Antarctica. In Madagascar, I analyzed data from a temporary network of broadband stations, along with data from three permanent stations. The seismic data have been processed and modeled using a wide range of techniques to characterize crust and mantle structure. Crustal structure in the East Antarctic Craton resembles Precambrian terrains around the world in its thickness and shear wave velocities. The West Antarctic Rift System has thinner crust, consistent with crustal thickness beneath other Cretaceous rifts. The Transantarctic Mountains show thickening of the crust from the costal regions towards the interior of the mountain range, and high velocities in the lower crust at several locations, possibly resulting from the Ferrar magmatic event. Ross Island and Marie Byrd Land Dome have elevated crustal Vp/Vs ratios, suggesting the presence of partial melt and/or volcaniclastic material within the crust. The pattern of seismic anisotropy in Madagascar is complex and cannot arise solely due to mantle flow from the African superplume, as previously proposed. To explain the complex pattern of anisotropy, a combination of mechanisms needs to be invoked, including mantle flow from the African superplume, mantle flow from the Comoros hotspot, small scale upwelling in the mantle induced by lithospheric delamination, and fossil anisotropy in the lithospheric mantle along Precambrian shear zones.

  11. Modeling continuous seismic velocity changes due to ground shaking in Chile

    Science.gov (United States)

    Gassenmeier, Martina; Richter, Tom; Sens-Schönfelder, Christoph; Korn, Michael; Tilmann, Frederik

    2015-04-01

    In order to investigate temporal seismic velocity changes due to earthquake related processes and environmental forcing, we analyze 8 years of ambient seismic noise recorded by the Integrated Plate Boundary Observatory Chile (IPOC) network in northern Chile between 18° and 25° S. The Mw 7.7 Tocopilla earthquake in 2007 and the Mw 8.1 Iquique earthquake in 2014 as well as numerous smaller events occurred in this area. By autocorrelation of the ambient seismic noise field, approximations of the Green's functions are retrieved. The recovered function represents backscattered or multiply scattered energy from the immediate neighborhood of the station. To detect relative changes of the seismic velocities we apply the stretching method, which compares individual autocorrelation functions to stretched or compressed versions of a long term averaged reference autocorrelation function. We use time windows in the coda of the autocorrelations, that contain scattered waves which are highly sensitive to minute changes in the velocity. At station PATCX we observe seasonal changes in seismic velocity as well as temporary velocity reductions in the frequency range of 4-6 Hz. The seasonal changes can be attributed to thermal stress changes in the subsurface related to variations of the atmospheric temperature. This effect can be modeled well by a sine curve and is subtracted for further analysis of short term variations. Temporary velocity reductions occur at the time of ground shaking usually caused by earthquakes and are followed by a recovery. We present an empirical model that describes the seismic velocity variations based on continuous observations of the local ground acceleration. Our hypothesis is that not only the shaking of earthquakes provokes velocity drops, but any small vibrations continuously induce minor velocity variations that are immediately compensated by healing in the steady state. We show that the shaking effect is accumulated over time and best described by

  12. Seismic and thermal structure of the crust and uppermost mantle beneath Antarctica from inversion of multiple seismic datasets

    Science.gov (United States)

    Wiens, D.; Shen, W.; Anandakrishnan, S.; Aster, R. C.; Gerstoft, P.; Bromirski, P. D.; Dalziel, I.; Hansen, S. E.; Heeszel, D.; Huerta, A. D.; Nyblade, A.; Stephen, R. A.; Wilson, T. J.; Winberry, J. P.; Stern, T. A.

    2017-12-01

    Since the last decade of the 20th century, over 200 broadband seismic stations have been deployed across Antarctica (e.g., temporary networks such as TAMSEIS, AGAP/GAMSEIS, POLENET/ANET, TAMNNET and RIS/DRIS by U.S. geoscientists as well as stations deployed by Japan, Britain, China, Norway, and other countries). In this presentation, we discuss our recent efforts to build reference crustal and uppermost mantle shear velocity (Vs) and thermal models for continental Antarctica based on those seismic arrays. By combing the high resolution Rayleigh wave dispersion maps derived from both ambient noise and teleseismic earthquakes, together with P receiver function waveforms, we develop a 3-D Vs model for the crust and uppermost mantle beneath Central and West Antarctica to a depth of 200 km. Additionally, using this 3-D seismic model to constrain the crustal structure, we re-invert for the upper mantle thermal structure using the surface wave data within a thermodynamic framework and construct a 3-D thermal model for the Antarctic lithosphere. The final product, a high resolution thermal model together with associated uncertainty estimates from the Monte Carlo inversion, allows us to derive lithospheric thickness and surface heat flux maps for much of the continent. West Antarctica shows a much thinner lithosphere ( 50-90 km) than East Antarctica ( 130-230 km), with a sharp transition along the Transantarctic Mountains (TAM). A variety of geological features, including a slower/hotter but highly heterogeneous West Antarctica and a much faster/colder East Antarctic craton, are present in the 3-D seismic/thermal models. Notably, slow seismic velocities observed in the uppermost mantle beneath the southern TAM are interpreted as a signature of lithospheric foundering and replacement with hot asthenosphere. The high resolution image of these features from the 3-D models helps further investigation of the dynamic state of Antarctica's lithosphere and underlying asthenosphere

  13. Strong Motion Network of Medellín and Aburrá Valley: technical advances, seismicity records and micro-earthquake monitoring

    Science.gov (United States)

    Posada, G.; Trujillo, J. C., Sr.; Hoyos, C.; Monsalve, G.

    2017-12-01

    The tectonics setting of Colombia is determined by the interaction of Nazca, Caribbean and South American plates, together with the Panama-Choco block collision, which makes a seismically active region. Regional seismic monitoring is carried out by the National Seismological Network of Colombia and the Accelerometer National Network of Colombia. Both networks calculate locations, magnitudes, depths and accelerations, and other seismic parameters. The Medellín - Aburra Valley is located in the Northern segment of the Central Cordillera of Colombia, and according to the Colombian technical seismic norm (NSR-10), is a region of intermediate hazard, because of the proximity to seismic sources of the Valley. Seismic monitoring in the Aburra Valley began in 1996 with an accelerometer network which consisted of 38 instruments. Currently, the network consists of 26 stations and is run by the Early Warning System of Medellin and Aburra Valley (SIATA). The technical advances have allowed the real-time communication since a year ago, currently with 10 stations; post-earthquake data is processed through operationally near-real-time, obtaining quick results in terms of location, acceleration, spectrum response and Fourier analysis; this information is displayed at the SIATA web site. The strong motion database is composed by 280 earthquakes; this information is the basis for the estimation of seismic hazards and risk for the region. A basic statistical analysis of the main information was carried out, including the total recorded events per station, natural frequency, maximum accelerations, depths and magnitudes, which allowed us to identify the main seismic sources, and some seismic site parameters. With the idea of a more complete seismic monitoring and in order to identify seismic sources beneath the Valley, we are in the process of installing 10 low-cost shake seismometers for micro-earthquake monitoring. There is no historical record of earthquakes with a magnitude

  14. Studies of the seismic coda using an earthquake cluster as a deeply buried seismograph array

    Science.gov (United States)

    Spudich, Paul; Bostwick, Todd

    1987-09-01

    Loosely speaking, the principle of Green's function reciprocity means that the source and receiver positions in a seismic experiment can be exchanged without affecting the observed seismograms. Consequently, the seismograms observed at a single observation location o and caused by a cluster of microearthquakes at locations {ei} are identical to the time series that would be measured by an array of stress meters emplaced at positions {ei}, recording waves generated by a source acting at o. By applying array analysis techniques like slant stacking and frequency-wave number analysis to these seismograms, we can determine the directions and velocities of the component waves as they travel in the earthquake focal region rather than at the surface. We have developed a computationally rapid plane-wave decomposition which we have applied to single-station recordings of aftershocks of the 1984 Morgan Hill, California, earthquake. The analysis is applied to data from three seismic stations having considerably different site geologies. One is a relatively hard rock station situated on Franciscan metamorphics, one is within the Calaveras fault zone, and one is on semiconsolidated sand and gravels. We define the early coda to be the part of the coda initiating immediately after the direct S wave and ending at twice the S wave lapse time. The character of the S wave and early coda varies from being impulsive at the first station to highly reverberative at the last. We examine waves in sequential time windows starting at the S wave and continuing through the early part of the coda. At all seismic stations the early coda is dominated by a persistent signal that must be caused by multiple scattering, probably within 2 km of each seismic station. Despite clear station-to-station differences in the character of the early coda, coda Q values measured in the late coda (greater than twice the S lapse time) agree well among stations, implying that the mechanisms causing the varying

  15. Studies Of Infrasonic Propagation Using Dense Seismic Networks

    Science.gov (United States)

    Hedlin, M. A.; deGroot-Hedlin, C. D.; Drob, D. P.

    2011-12-01

    Although there are approximately 100 infrasonic arrays worldwide, more than ever before, the station density is still insufficient to provide validation for detailed propagation modeling. Relatively large infrasonic signals can be observed on seismic channels due to coupling at the Earth's surface. Recent research, using data from the 70-km spaced 400-station USArray and other seismic network deployments, has shown the value of dense seismic network data for filling in the gaps between infrasonic arrays. The dense sampling of the infrasonic wavefield has allowed us to observe complete travel-time branches of infrasound and address important research problems in infrasonic propagation. We present our analysis of infrasound created by a series of rocket motor detonations that occurred at the UTTR facility in Utah in 2007. These data were well recorded by the USArray seismometers. We use the precisely located blasts to assess the utility of G2S mesoscale models and methods to synthesize infrasonic propagation. We model the travel times of the branches using a ray-based approach and the complete wavefield using a FDTD algorithm. Although results from both rays and FDTD approaches predict the travel times to within several seconds, only about 40% of signals are predicted using rays largely due to penetration of sound into shadow zones. FDTD predicts some sound penetration into the shadow zone, but the observed shadow zones, as defined by the seismic data, have considerably narrower spatial extent than either method predicts, perhaps due to un-modeled small-scale structure in the atmosphere.

  16. Local seismic network at the Olkiluoto site. Annual report for 2013

    International Nuclear Information System (INIS)

    Saari, J.; Malm, M.

    2014-06-01

    This report gives the results of microseismic monitoring during 2013. Excavation of the underground rock characterisation facility called ONKALO started in 2004. Before that, in February 2002, Posiva Oy established a local seismic network of six stations on the island of Olkiluoto, where there are currently 17 seismic stations and 21 triaxial sensors. The network has operated continuously in 2013. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas, of which the larger one, the seismic semiregional area, includes the Olkiluoto island and its surroundings. The purpose is to monitor explosions and tectonic earthquakes in regional scale inside that area. All the expected excavation induced events are assumed to occur inside the smaller target area, the seismic ONKALO block, which is a 2 km x 2 km x 2 km cube surrounding the ONKALO and includes 13 seismic stations. An additional task of monitoring is related to safeguarding of the construction of ONKALO. Upgrade and unification of the whole seismic network was done in August 2013. The upgrade included communication, data acquisition, server equipment in Olkiluoto, network configuration and software. The bedrock models and the ONKALO design model applied in the visualisation of the seismicity remained the same in 2013. The number of located events was much smaller than during previous years due to break in the excavation. Altogether 436 events have been located in the Olkiluoto area, in the reported time period. Nearly half of the observed explosions (237) in 2013 occurred inside the seismic semi-regional area and especially inside the seismic ONKALO block (137). The magnitudes of the explosions inside the semi-regional area range from M L = -1.6 to M L = 1.5 (M L = magnitude in local Richter's scale). One small induced earthquake (ML = -1.8) was detected on 9 May 2013

  17. UMTS rapid response real-time seismic networks: implementation and strategies at INGV

    Science.gov (United States)

    Govoni, A.; Margheriti, L.; Moretti, M.; Lauciani, V.; Sensale, G.; Bucci, A.; Criscuoli, F.

    2015-12-01

    Universal Mobile Telecommunications System (UMTS) and its evolutions are nowadays the most affordable and widespread data communication infrastructure available almost world wide. Moreover the always growing cellular phone market is pushing the development of new devices with higher performances and lower power consumption. All these characteristics make UMTS really useful for the implementation of an "easy to deploy" temporary real-time seismic station. Despite these remarkable features, there are many drawbacks that must be properly taken in account to effectively transmit the seismic data: Internet security, signal and service availability, power consumption. - Internet security: exposing seismological data services and seismic stations to the Internet is dangerous, attack prone and can lead to downtimes in the services, so we setup a dedicated Virtual Private Network (VPN) service to protect all the connected devices. - Signal and service availability: while for temporary experiment a carefull planning and an accurate site selection can minimize the problem, this is not always the case with rapid response networks. Moreover, as with any other leased line, the availability of the UMTS service during a seismic crisis is basically unpredictable. Nowadays in Italy during a major national emergency a Committee of the Italian Civil Defense ensures unified management and coordination of emergency activities. Inside it the telecom companies are committed to give support to the crisis management improving the standards in their communication networks. - Power consumption: it is at least of the order of that of the seismic station and, being related to data flow and signal quality is largely unpredictable. While the most secure option consists in adding a second independent solar power supply to the seismic station, this is not always a very convenient solution since it doubles the cost and doubles the equipment on site. We found that an acceptable trade-off is to add an

  18. Quantifying capability of a local seismic network in terms of locations and focal mechanism solutions of weak earthquakes

    Science.gov (United States)

    Fojtíková, Lucia; Kristeková, Miriam; Málek, Jiří; Sokos, Efthimios; Csicsay, Kristián; Zahradník, Jiří

    2016-01-01

    Extension of permanent seismic networks is usually governed by a number of technical, economic, logistic, and other factors. Planned upgrade of the network can be justified by theoretical assessment of the network capability in terms of reliable estimation of the key earthquake parameters (e.g., location and focal mechanisms). It could be useful not only for scientific purposes but also as a concrete proof during the process of acquisition of the funding needed for upgrade and operation of the network. Moreover, the theoretical assessment can also identify the configuration where no improvement can be achieved with additional stations, establishing a tradeoff between the improvement and additional expenses. This paper presents suggestion of a combination of suitable methods and their application to the Little Carpathians local seismic network (Slovakia, Central Europe) monitoring epicentral zone important from the point of seismic hazard. Three configurations of the network are considered: 13 stations existing before 2011, 3 stations already added in 2011, and 7 new planned stations. Theoretical errors of the relative location are estimated by a new method, specifically developed in this paper. The resolvability of focal mechanisms determined by waveform inversion is analyzed by a recent approach based on 6D moment-tensor error ellipsoids. We consider potential seismic events situated anywhere in the studied region, thus enabling "mapping" of the expected errors. Results clearly demonstrate that the network extension remarkably decreases the errors, mainly in the planned 23-station configuration. The already made three-station extension of the network in 2011 allowed for a few real data examples. Free software made available by the authors enables similar application in any other existing or planned networks.

  19. TOMO-ETNA MED-SUV.ISES an active seismic and passive seismic experiment at Mt. Etna volcano. An integrated marine and onland geophysical survey.

    Science.gov (United States)

    Ibáñez, Jesus. M.; Patane, Domenico; Puglisi, Guisseppe; Zuccarello, Lucciano; Bianco, Francesca; Luehr, Birger; Diaz-Moreno, Alejandro; Prudencio, Janire; Koulakov, Ivan; Del Pezzo, Edoardo; Cocina, Ornella; Coltelli, Mauro; Scarfi, Lucciano; De Gori, Pascuale; Carrion, Francisco

    2014-05-01

    An active seismic experiment to study the internal structure of Etna Volcano is going to carried out on Sicily and Aeolian islands. The main objective of the TOMO-ETNA MED-SUV.ISES experiment, beginning in summer 2014, is to perform a high resolution seismic tomography, in velocity and attenuation, in Southern Italy, by using active and passive seismic data, in an area encompassing outstanding volcanoes as Mt. Etna, and Aeolian volcanoes. The achievement of this objective is based on the integration and sharing of the in-situ marine and land experiments and observations and on the implementation of new instruments and monitoring systems. For the purpose, onshore and offshore seismic stations and passive and active seismic data generated both in marine and terrestrial environment will be used. Additionally, other geophysical data, mainly magnetic and gravimetric data will be considered to obtain a joint Upper Mantle-Crust structure that could permit to make progress in the understanding of the dynamic of the region. This multinational experiment which involves institutions from Spain, Italy, Germany, United Kingdom, Ireland, France, Malta, Portugal, Russia, USA and Mexico. During the experiment more than 6.600 air gun shots performed by the Spanish Oceanographic vessel "Sarmiento de Gamboa" will be recorder on a dense local seismic network consisting of 100 on land non-permanent stations, 70 on land permanent stations and 20-25 OBSs. Contemporaneously other marine geophysical measures will be performed using a marine Gravimeter LaCoste&Romberg Air-Sea Gravity System II and a Marine Magnetometer SeaSPY. The experiments will provide a unique data set in terms of data quantity and quality, and it will provide a detailed velocity and attenuation structural image of volcano edifice. The results will be essential in the development and interpretation of future volcanic models. It is noteworthy that this project is fully transversal, multidisciplinary and crosses several

  20. Instrumentation qualification. Seismic qualification of C-E instrumentation equipment. Part One

    International Nuclear Information System (INIS)

    1977-05-01

    A summary of the C-E seismic qualification program utilized to demonstrate the seismic design adequacy of the instrumentation and control equipment used in C-E supplied Nuclear Steam Supply Systems (NSSS) is presented. The report is divided into two parts. Part One includes the equipment seismic requirements and a description of the qualification methods. Part Two lists the specific equipment by nuclear station in which it is used and the equipment test results are summarized in a standard data sheet format to facilitate review. The seismic requirements are based on individual contract commitments with C-E customers and the NRC Standard Review Plan, Section 3.10 ''Seismic Qualification of Category I Instrumentation and Electrical Equipment.'' Equipment is qualified for use in a seismic environment where damage potential to the equipment is less than or equal to that simulated seismic environment to which it has been qualified. The anticipated Safe Shutdown Earthquake (SSE) environment at the inservice location of equipment should be confirmed by each applicant as not exceeding that to which it is qualified

  1. Analysis of Bracket Assembly for Portable Leak Detector Station

    International Nuclear Information System (INIS)

    ZIADA, H.H.

    1999-01-01

    This Supporting Document Presents Structural and Stress Analysis of a Portable Leak Detector Station for Tank Farms. The results show that the bracket assembly meets the requirements for dead load and natural phenomena hazards loads (seismic and wind)

  2. Third Quarter Hanford Seismic Report for Fiscal Year 2008

    Energy Technology Data Exchange (ETDEWEB)

    Rohay, Alan C.; Sweeney, Mark D.; Hartshorn, Donald C.; Clayton, Ray E.; Devary, Joseph L.

    2008-09-01

    . The May 18 event, not reported as being felt on the Hanford site or causing any damage, was communicated to the PNNL Operations Center per HSAP communications procedures. The event is not considered to be significant with regard to site safety and not unprecedented given the site’s seismic history. The Hanford strong motion accelerometer (SMA) stations at the 200 East Area, 300 Area, and the 400 Area were triggered by the May 18 event. The reportable action level of 2% g for Hanford facilities is approximately 12 times larger than the peak acceleration (0.17%) observed at the 300 Area SMA station and no action was required.

  3. A study of local site effects in Benevento(Southern Italy by the analysis of seismic records of explosions

    Directory of Open Access Journals (Sweden)

    L. Mirabile

    1995-06-01

    Full Text Available In this paper we evalllate the seismic amplification effects in the town of Benevento llsing records of an explo- sion of 500 kg fired at abollt 7 km. Seismic records were obtained at 43 selected sites in the city by digital three-component stations. A data selection performed on the signal-to-noise ratio reduced the available data to 26 stations. We used the spectral ratio techniques to evaluate the amplification effects of each recording site compared both to the average spectrum calculated over 26 stations and to a reference seismic station. The shapes of the spectral ratios were classified according to the geological characteristics of the site. A characteristic shape of the spectral ratio was observed to be related to the specific structure of the subsoil. In particular, the sites on basin sediments (Lagonegro Unit and Middle Pleistocene conglomerates failed to show amplification effects; the sites on thick alluvial deposits showed amplification in the 5-9 Hz range; finally, sites on alluvial-lacustrine deposits amplified the seismic signal at frequencies depending on the characteristics and the thickness of the deposit. In addition, damage distribution caused by the 1688 earthquake in Benevento was related to the thickness of the surface layers in the ancient built-up area of the town. The study of the spectral ra- tios showed that these deposits amplify ground motion at frequencies between 9 and 12 Hz, i.e. frequencies close to the natural period of the most widespread buildings at that time in Benevento. Geological and seismic data were jointly used to carry out a zonation of the urban area of Benevento on the basis of homogeneous seismic responses. The validity of this analysis is limited to the main frequency band and amplitude of ground motion produced by the explosions.

  4. Induced Seismicity Monitoring System

    Science.gov (United States)

    Taylor, S. R.; Jarpe, S.; Harben, P.

    2014-12-01

    There are many seismological aspects associated with monitoring of permanent storage of carbon dioxide (CO2) in geologic formations. Many of these include monitoring underground gas migration through detailed tomographic studies of rock properties, integrity of the cap rock and micro seismicity with time. These types of studies require expensive deployments of surface and borehole sensors in the vicinity of the CO2 injection wells. Another problem that may exist in CO2 sequestration fields is the potential for damaging induced seismicity associated with fluid injection into the geologic reservoir. Seismic hazard monitoring in CO2 sequestration fields requires a seismic network over a spatially larger region possibly having stations in remote settings. Expensive observatory-grade seismic systems are not necessary for seismic hazard deployments or small-scale tomographic studies. Hazard monitoring requires accurate location of induced seismicity to magnitude levels only slightly less than that which can be felt at the surface (e.g. magnitude 1), and the frequencies of interest for tomographic analysis are ~1 Hz and greater. We have developed a seismo/acoustic smart sensor system that can achieve the goals necessary for induced seismicity monitoring in CO2 sequestration fields. The unit is inexpensive, lightweight, easy to deploy, can operate remotely under harsh conditions and features 9 channels of recording (currently 3C 4.5 Hz geophone, MEMS accelerometer and microphone). An on-board processor allows for satellite transmission of parameter data to a processing center. Continuous or event-detected data is kept on two removable flash SD cards of up to 64+ Gbytes each. If available, data can be transmitted via cell phone modem or picked up via site visits. Low-power consumption allows for autonomous operation using only a 10 watt solar panel and a gel-cell battery. The system has been successfully tested for long-term (> 6 months) remote operations over a wide range

  5. European database of nuclear-seismic profiles. Final report

    International Nuclear Information System (INIS)

    Wenzel, F.; Fuchs, K.; Tittgemeyer, M.

    1997-01-01

    The project serves the purpose of conserving the nuclear-seismic data collections of the former USSR by suitable processing of data as well as digitization, and incorporation into the databases stored at Potsdam (Germany) and Moscow (Russia). In a joint activity assisted by the Russian State Committee for Geology, a complete set of nuclear-seismic data has been integrated into the data collections of an international computer center which is one of the centers participating in the EUROPROBE project. Furthermore, computer stations are being established across Russia so that Russian geoscientists will have at their disposal the required data processing facilities. (DG) [de

  6. The 2017 Maple Creek Seismic Swarm in Yellowstone National Park

    Science.gov (United States)

    Pang, G.; Hale, J. M.; Farrell, J.; Burlacu, R.; Koper, K. D.; Smith, R. B.

    2017-12-01

    The University of Utah Seismograph Stations (UUSS) performs near-real-time monitoring of seismicity in the region around Yellowstone National Park in partnership with the United States Geological Survey and the National Park Service. UUSS operates and maintains 29 seismic stations with network code WY (short-period, strong-motion, and broadband) and records data from five other seismic networks—IW, MB, PB, TA, and US—to enhance the location capabilities in the Yellowstone region. A seismic catalog is produced using a conventional STA/LTA detector and single-event location techniques (Hypoinverse). On June 12, 2017, a seismic swarm began in Yellowstone National Park about 5 km east of Hebgen Lake. The swarm is adjacent to the source region of the 1959 MW 7.3 Hebgen Lake earthquake, in an area corresponding to positive Coulumb stress change from that event. As of Aug. 1, 2017, the swarm consists of 1481 earthquakes with 1 earthquake above magnitude 4, 8 earthquakes in the magnitude 3 range, 115 earthquakes in the magnitude 2 range, 469 earthquakes in the magnitude 1 range, 856 earthquakes in the magnitude 0 range, 22 earthquakes with negative magnitudes, and 10 earthquakes with no magnitude. Earthquake depths are mostly between 3 and 10 km and earthquake depth increases toward the northwest. Moment tensors for the 2 largest events (3.6 MW and 4.4. MW) show strike-slip faulting with T axes oriented NE-SW, consistent with the regional stress field. We are currently using waveform cross-correlation methods to measure differential travel times that are being used with the GrowClust program to generate high-accuracy relative relocations. Those locations will be used to identify structures in the seismicity and make inferences about the tectonic and magmatic processes causing the swarm.

  7. Towards a Systematic Search for Triggered Seismic Events in the USA

    Science.gov (United States)

    Tang, V.; Chao, K.; Van der Lee, S.

    2017-12-01

    Dynamic triggering of small earthquakes and tectonic tremor by small stress variations associated with passing surface waves from large-magnitude teleseismic earthquakes have been observed in seismically active regions in the western US. Local stress variations as small as 5 10 kPa can suffice to advance slip on local faults. Observations of such triggered events share certain distinct characteristics. With an eye towards an eventual application of machine learning, we began a systematic search for dynamically triggered seismic events in the USA that have these characteristics. Such a systematic survey has the potential to help us to better understand the fundamental process of dynamic triggering and hazards implied by it. Using visual inspection on top of timing and frequency based selection criteria for these seismic phenomena, our search yielded numerous false positives, indicating the challenge posed by moving from ad-hoc observations of dynamic triggering to a systematic search that also includes a catalog of non-triggering, even when sufficient stress variations are supplied. Our search includes a dozen large earthquakes that occurred during the tenure of USArray. One of these earthquakes (11 April 2012 Mw8.6 Sumatra), for example, was observed by USArray-TA stations in the Midwest and other station networks (such as PB and UW), and yielded candidate-triggered events at 413 stations. We kept 79 of these observations after closer visual inspection of the observed events suggested distinct P and S arrivals from a local earthquake, or a tremor modulation with the same period as the surface wave, among other criteria. We confirmed triggered seismic events in 63 stations along the western plate boundary where triggered events have previously been observed. We also newly found triggered tremor sources in eastern Oregon and Yellowstone, and candidate-triggered earthquake sources in New Mexico and Minnesota. Learning whether 14 of remaining candidates are confirmed

  8. Eagle Pass Jr. High Seismology Team: Strategies for Engaging Middle School "At-Risk" Students in Authentic Research

    Science.gov (United States)

    Brunt, M. R.; Ellins, K. K.; Frohlich, C. A.

    2011-12-01

    In 2008, during my participation in the NSF-sponsored Texas Earth & Space Science (TXESS) Revolution professional development program, I was awarded an AS-1 seismograph through IRIS's Seismographs in Schools Program. This program serves to create an international educational seismic network that allows teachers across the country and around the world to share seismic data in real-time using online tools, classroom activities, and technical support documents for seismic instruments. Soon after receiving my AS-1, I founded and began sponsoring the Eagle Pass Jr. High Seismology Team which consists of selected 7th and 8th grade students. Eagle Pass Jr. High is a Title 1 school that serves a predominantly "at-risk" Hispanic population. We meet after school once a week to learn about earthquakes, seismic waves, analyze recorded seismic event data using computer software programming, and correspond with other students from schools around the country. This team approach has been well received by fellow TXESS Revolution teachers with AS-1 seismographs and will be implemented by David Boyd, STEM coordinator for Williams Preparatory Academy in Dallas, Texas this fall 2011. All earthquakes recorded by our seismograph station (EPTX), which has remained online and actively recording seismic data since 2008, are catalogued and then plotted on a large world map displayed on my classroom wall. A real-time seismogram image updates every five minutes and along with all earthquakes recorded since installation can be viewed on our webpage http://www.iris.edu/hq/ssn/schools/view/eptx. During the 2010-2011 school year, my seismology team and I participated in an earthquake research study led by Dr. Cliff Frohlich at the Institute for Geophysics. The study examined seismograms and felt reports for the 25 April 2010 Alice, Texas, earthquake, in order to investigate its possible connection to oil and gas production in the Stratton oil and gas field. A research paper detailing our findings

  9. Georgia-Armenia Transboarder seismicity studies

    Science.gov (United States)

    Godoladze, T.; Tvaradze, N.; Javakishvili, Z.; Elashvili, M.; Durgaryan, R.; Arakelyan, A.; Gevorgyan, M.

    2012-12-01

    In the presented study we performed Comprehensive seismic analyses for the Armenian-Georgian transboarder active seismic fault starting on Armenian territory, cutting the state boarder and having possibly northern termination on Adjara-Triealeti frontal structure in Georgia. In the scope of International projects: ISTC A-1418 "Open network of scientific Centers for mitigation risk of natural hazards in the Southern Caucasus and Central Asia" and NATO SfP- 983284 Project "Caucasus Seismic Emergency Response" in Akhalkalaki (Georgia) seismic center, Regional Summer school trainings and intensive filed investigations were conducted. Main goal was multidisciplinary study of the Javakheti fault structure and better understanding seismicity of the area. Young scientists from Turkey, Armenia, Azerbaijan and Georgia were participated in the deployment of temporal seismic network in order to monitor seisimity on the Javakheti highland and particularly delineate fault scarf and identify active seismic structures. In the scope of international collaboration the common seismic database has been created in the southern Caucasus and collected data from the field works is available now online. Javakheti highland, which is located in the central part of the Caucasus, belongs to the structure of the lesser Caucasus and represents a history of neotectonic volcanism existed in the area. Jasvakheti highland is seismicalu active region devastating from several severe earthquakes(1088, 1283, 1899…). Hypocenters located during analogue network were highly scattered and did not describe real pattern of seismicity of the highland. We relocated hypocenters of the region and improved local velocity model. The hypocenters derived from recently deployed local seismic network in the Javakheti highland, clearly identified seismically active structures. Fault plane solutions of analogue data of the Soviet times have been carefully analyzed and examined. Moment tensor inversion were preformed

  10. Local seismic tomography in Belgium - implications for the geological structure.

    Science.gov (United States)

    Sichien, E.; Camelbeek, T.; Henriet, J.-P.

    2009-04-01

    We present the results of a local seismic tomography in Belgium using well-located local earthquakes registered by 37 stations of the permanent seismic network and by mobile stations installed by the Royal Observatory of Belgium. Previous studies did not offer a lot of information on the middle and lower crust. The seismic profiles shot in the region (Belcorp, Decorp, Ecors, …) all show an unreflective middle and lower crust. The gravimetric and magnetic data show the presence of a sharp transition between the Brabant Massive and the Ardennes allochtone, furthermore, a broad positive gravimetric anomaly, is interpreted as a Moho uplift underneath the Campine region. Our results confirm the sharp transition between the Brabant Massif (higher than expected velocities) and the Ardennes allochtone (lower than expected velocities). At 27 km of depth lower crust - upper mantle velocities (7.50 km/s) are found underneath the Campine region and the Eifelplume region, confirming the Moho uplifts to 28 km underneath these regions. At 13 km similar velocities (7.50 km/s) are seen underneath the Eifelplume, they correspond to a lower crust-upper mantle that trusted in the crust during the Variscan orogeny.

  11. Academia Sinica, TW E-science to Assistant Seismic Observations for Earthquake Research, Monitor and Hazard Reduction Surrounding the South China Sea

    Science.gov (United States)

    Huang, Bor-Shouh; Liu, Chun-Chi; Yen, Eric; Liang, Wen-Tzong; Lin, Simon C.; Huang, Win-Gee; Lee, Shiann-Jong; Chen, Hsin-Yen

    Experience from the 1994 giant Sumatra earthquake, seismic and tsunami hazard have been considered as important issues in the South China Sea and its surrounding region, and attracted many seismologist's interesting. Currently, more than 25 broadband seismic instruments are currently operated by Institute of Earth Sciences, Academia Sinica in northern Vietnam to study the geodynamic evolution of the Red river fracture zone and rearranged to distribute to southern Vietnam recently to study the geodynamic evolution and its deep structures of the South China Sea. Similar stations are planned to deploy in Philippines in near future. In planning, some high quality stations may be as permanent stations and added continuous GPS observations, and instruments to be maintained and operated by several cooperation institutes, for instance, Institute of Geophysics, Vietnamese Acadamy of Sciences and Technology in Vietnam and Philippine Institute of Volcanology and Seismology in Philippines. Finally, those stations will be planed to upgrade as real time transmission stations for earthquake monitoring and tsunami warning. However, high speed data transfer within different agencies is always a critical issue for successful network operation. By taking advantage of both EGEE and EUAsiaGrid e-Infrastructure, Academia Sinica Grid Computing Centre coordinates researchers from various Asian countries to construct a platform to high performance data transfer for huge parallel computation. Efforts from this data service and a newly build earthquake data centre for data management may greatly improve seismic network performance. Implementation of Grid infrastructure and e-science issues in this region may assistant development of earthquake research, monitor and natural hazard reduction. In the near future, we will search for new cooperation continually from the surrounding countries of the South China Sea to install new seismic stations to construct a complete seismic network of the

  12. The Applicability of Incoherent Array Processing to IMS Seismic Array Stations

    Science.gov (United States)

    Gibbons, S. J.

    2012-04-01

    The seismic arrays of the International Monitoring System for the CTBT differ greatly in size and geometry, with apertures ranging from below 1 km to over 60 km. Large and medium aperture arrays with large inter-site spacings complicate the detection and estimation of high frequency phases since signals are often incoherent between sensors. Many such phases, typically from events at regional distances, remain undetected since pipeline algorithms often consider only frequencies low enough to allow coherent array processing. High frequency phases that are detected are frequently attributed qualitatively incorrect backazimuth and slowness estimates and are consequently not associated with the correct event hypotheses. This can lead to missed events both due to a lack of contributing phase detections and by corruption of event hypotheses by spurious detections. Continuous spectral estimation can be used for phase detection and parameter estimation on the largest aperture arrays, with phase arrivals identified as local maxima on beams of transformed spectrograms. The estimation procedure in effect measures group velocity rather than phase velocity and the ability to estimate backazimuth and slowness requires that the spatial extent of the array is large enough to resolve time-delays between envelopes with a period of approximately 4 or 5 seconds. The NOA, AKASG, YKA, WRA, and KURK arrays have apertures in excess of 20 km and spectrogram beamforming on these stations provides high quality slowness estimates for regional phases without additional post-processing. Seven arrays with aperture between 10 and 20 km (MJAR, ESDC, ILAR, KSRS, CMAR, ASAR, and EKA) can provide robust parameter estimates subject to a smoothing of the resulting slowness grids, most effectively achieved by convolving the measured slowness grids with the array response function for a 4 or 5 second period signal. The MJAR array in Japan recorded high SNR Pn signals for both the 2006 and 2009 North Korea

  13. OGS improvements in the year 2011 in running the Northeastern Italy Seismic Network

    Science.gov (United States)

    Bragato, P. L.; Pesaresi, D.; Saraò, A.; Di Bartolomeo, P.; Durı, G.

    2012-04-01

    The Centro di Ricerche Sismologiche (CRS, Seismological Research Center) of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS, Italian National Institute for Oceanography and Experimental Geophysics) in Udine (Italy) after the strong earthquake of magnitude M=6.4 occurred in 1976 in the Italian Friuli-Venezia Giulia region, started to operate the Northeastern Italy Seismic Network: it currently consists of 15 very sensitive broad band and 21 simpler short period seismic stations, all telemetered to and acquired in real time at the OGS-CRS data center in Udine. Real time data exchange agreements in place with other Italian, Slovenian, Austrian and Swiss seismological institutes lead to a total number of about 100 seismic stations acquired in real time, which makes the OGS the reference institute for seismic monitoring of Northeastern Italy. Since 2002 OGS-CRS is using the Antelope software suite on several workstations plus a SUN Cluster as the main tool for collecting, analyzing, archiving and exchanging seismic data, initially in the framework of the EU Interreg IIIA project "Trans-national seismological networks in the South-Eastern Alps". SeisComP is also used as a real time data exchange server tool. In order to improve the seismological monitoring of the Northeastern Italy area, at OGS-CRS we tuned existing programs and created ad hoc ones like: a customized web server named PickServer to manually relocate earthquakes, a script for automatic moment tensor determination, scripts for web publishing of earthquake parametric data, waveforms, state of health parameters and shaking maps, noise characterization by means of automatic spectra analysis, and last but not least scripts for email/SMS/fax alerting. The OGS-CRS Real Time Seismological website (RTS, http://rts.crs.inogs.it/) operative since several years was initially developed in the framework of the Italian DPC-INGV S3 Project: the RTS website shows classic earthquake locations

  14. Local seismic network at the Olkiluoto site. Annual Report for 2007

    International Nuclear Information System (INIS)

    Saari, J.; Lakio, A.

    2008-05-01

    In February 2002, Posiva Oy established a local seismic network of six stations on the island of Olkiluoto. Later, in June 2004, the seismic network was expanded with two new seismic stations. At that time started the excavation of the underground characterisation facility (the ONKALO) and the basic operation procedure was changed more suitable for the demands of the new situation. In the beginning of 2006, the target area of the seismic monitoring expanded to semiregional scale. Four new seismic stations started in the beginning of February 2006 and the focus of interpretation was expanded to an area, called the seismic semi-regional area. At the end of 2006, two new borehole geophones were installed in order to improve the sensitivity and the depth resolution of the measurements inside the ONKALO block. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The studies include both tectonic and excavation-induced microearthquakes. An additional task of monitoring is related to safeguarding of the ONKALO. This report gives the results of microseismic monitoring during the year 2007. Also the changes in the structure and the operation procedure of the network are described. The true orientation of the borehole sensor OL-OS13 was calculated. The correct orientation of triaxial seismometer is essential when the fault plane solution of an earthquake is calculated. The other borehole sensor OL-OS14 was permanently disconnected in October 2007. The network has operated continuously in 2007. Altogether 2207 events have been located in the Olkiluoto area, in reported time period. Altogether 2207 events have been located in 2007. Most of them (1912) are explosions occurred inside the seismic semiregional area and especially inside the ONKALO block (1891 events). The magnitudes of the observed events inside the semi-regional area range from ML = -2.1 to ML = 1.5 (ML

  15. Seismic Performance Assessment and Strengthening of Gazimagusa Namik Kemal Lisesi

    OpenAIRE

    Yardımcı, Temuçin

    2009-01-01

    ABSTRACT: Many destructive earthquakes occurred in Cyprus. However, the potential seismic risk of the buildings in Cyprus is not known well since vulnerability is unknown. Especially in the Northern part of the Island building inventory has variation regarding seismic performance. On the other hand, in Northern Cyprus there are more than 150 school buildings with different ages. Most of these buildings have been constructed before the use of modern seismic codes. In other words, only gravity...

  16. Lunar seismicity, structure, and tectonics

    Science.gov (United States)

    Lammlein, D. R.; Latham, G. V.; Dorman, J.; Nakamura, Y.; Ewing, M.

    1974-01-01

    Natural seismic events have been detected by the long-period seismometers at Apollo stations 16, 14, 15, and 12 at annual rates of 3300, 1700, 800, and 700, respectively, with peak activity at 13- to 14-day intervals. The data are used to describe magnitudes, source characteristics, and periodic features of lunar seismicity. In a present model, the rigid lithosphere overlies an asthenosphere of reduced rigidity in which present-day partial melting is probable. Tidal deformation presumably leads to critical stress concentrations at the base of the lithosphere, where moonquakes are found to occur. The striking tidal periodicities in the pattern of moonquake occurrence and energy release suggest that tidal energy is the dominant source of energy released as moonquakes. Thus, tidal energy is dissipated by moonquakes in the lithosphere and probably by inelastic processes in the asthenosphere.

  17. Man-caused seismicity of Kuzbass

    Science.gov (United States)

    Emanov, Alexandr; Emanov, Alexey; Leskova, Ekaterina; Fateyev, Alexandr

    2010-05-01

    A natural seismicity of Kuznetsk Basin is confined in the main to mountain frame of Kuznetsk hollow. In this paper materials of experimental work with local station networks within sediment basin are presented. Two types of seismicity display within Kuznetsk hollow have been understood: first, man-caused seismic processes, confined to mine working and concentrated on depths up to one and a half of km; secondly, seismic activations on depths of 2-56 km, not coordinated in plan with coal mines. Every of studied seismic activations consists of large quantity of earthquakes of small powers (Ms=1-3). From one to first tens of earthquakes were recorded in a day. The earthquakes near mine working shift in space along with mine working, and seismic process become stronger at the instant a coal-plough machine is operated, and slacken at the instant the preventive works are executed. The seismic processes near three lavas in Kuznetsk Basin have been studied in detail. Uplift is the most typical focal mechanism. Activated zone near mine working reach in diameter 1-1,5 km. Seismic activations not linked with mine working testify that the subsoil of Kuznetsk hollow remain in stress state in whole. The most probable causes of man-caused action on hollow are processes, coupled with change of physical state of rocks at loss of methane from large volume or change by mine working of rock watering in large volume. In this case condensed rocks, lost gas and water, can press out upwards, realizing the reverse fault mechanism of earthquakes. A combination of stress state of hollow with man-caused action at deep mining may account for incipient activations in Kuznetsk Basin. Today earthquakes happen mainly under mine workings, though damages of workings themselves do not happen, but intensive shaking on surface calls for intent study of so dangerous phenomena. In 2009 replicates of the experiment on research of seismic activations in area of before investigated lavas have been conducted

  18. New insights of seismic disturbances due to wind turbines - long and short term measurements in SW Germany

    Science.gov (United States)

    Zieger, Toni; Ritter, Joachim

    2017-04-01

    Within the scope of the project "TremAc", we present new insights of ground motion disturbances due to wind turbines (WTs) in the vicinity of the town of Landau, SW Germany. The main goal of this project, which is funded by the German Federal Ministry for Economic Affairs and Energy, is the detection of influences from WTs on human health and buildings in an interdisciplinary way. The interaction between WTs, humans, infrastructure (incl.seismic stations) becomes more and more an important role with the increase of installed WTs. We present averaged one hour long PSD-spectra in a frequency range from 0.5 Hz to 7 Hz depending on the wind speed before and after the installation of characteristic WTs, especially for seismic borehole stations, during one month measurements. The results show a clear increase of the ground motion and a related disturbance of the seismic recordings. The station threshold for signal detection below 2 Hz is reduced after the installation of a new wind farm in the area around Landau. This effect occurs even up to distances to the WTs of more than 5 kilometers. The increasing noise level depends also clearly on wind speed, which indicate also the WT origin related with the signals. Using short-term measurements during few hours, we are able to determine the maximum of the PSD values for different discrete frequencies as function of distance to the next WT and to fit a power-law decay curve proportional to 1/rb to the data. In this way we can differentiate between near- and far-field effects of the seismic wave propagation of WTs. A clear frequency dependent decay can be observed, for which high frequencies are more attenuated than lower frequencies, probably due to scattering processes. The new results will help for a better understanding of WTs as a seismic noise source and their interaction with nearby seismic stations and other infrastructure. Seismic data were provided by "Erdbebendienst Südwest", "Federal Institute for Geosciences and

  19. Seismic Safety Margins Research Program: a concluding look

    International Nuclear Information System (INIS)

    Cummings, G.E.

    1984-01-01

    The Seismic Safety Margins Research Program (SSMRP) was started in 1978 with the goal of developing tools and data bases to compute the probability of earthquake - caused radioactive release from commercial nuclear power plants. These tools and data bases were to help NRC to assess seismic safety at nuclear plants. The methodology to be used was finalized in 1982 and applied to the Zion Nuclear Power Station. The SSMRP will be completed this year with the development of a more simplified method of analysis and a demonstration of its use on Zion. This simplified method is also being applied to a boiling-water-reactor, LaSalle

  20. Seismic analysis of mechanical systems at Pickering NGS

    International Nuclear Information System (INIS)

    Ghobarah, A.

    1995-11-01

    The objective of this study is to assess the seismic withstand capacity of selected safety-related mechanical systems associated with the Pressure Relief Duct (PRD) at the Pickering A Nuclear Generating Station. These systems are attached to the PRD and include the Emergency Coolant Injection System piping, the Vacuum Ducts, the Emergency Water Storage System, the PRD expansion joint seals and the PRD to Reactor Building joint seals. The input support motion to the mechanical systems is taken to be the seismic response of the PRD determined in an earlier study using various levels of predetermined ground response spectrum envelope. (author). 12 refs., 13 tabs., 48 figs

  1. Complex Seismic Anisotropy at the Edges of a Very-low Velocity Province in the Lowermost Mantle

    Science.gov (United States)

    Wang, Y.; Wen, L.

    2005-12-01

    A prominent very-low velocity province (VLVP) in the lowermost mantle is revealed, and has been extensively mapped out in recent seismic studies (e.g., Wang and Wen, 2004). Seismic evidence unambiguously indicates that the VLVP is compositionally distinct, and its seismic structure can be best explained by partial melting driven by a compositional change produced in the early Earth's history (Wen, 2001; Wen et. al, 2001; Wang and Wen, 2004). In this presentation, we study the seismic anisotropic behavior inside the VLVP and its surrounding area using SKS and SKKS waveform data. We collect 272 deep earthquakes recorded by more than 80 stations in the Kaapvaal seismic array in southern Africa from 1997 to 1999. Based on the data quality, we choose SKS and SKKS waveform data for 16 earthquakes to measure the anisotropic parameters: the fast polarization direction and the splitting time, using the method of Silver and Chan (1991). A total of 162 high-quality measurements are obtained based on the statistics analysis of shear wave splitting results. The obtained anisotropy exhibits different patterns for the SKS and SKKS phases sampling inside the VLVP and at the edges of the VLVP. When the SKS and SKKS phases sample inside the VLVP, their fast polarization directions exhibit a pattern that strongly correlates with stations, gradually changing from 11°N~to 80°N~across the seismic array from south to north and rotating back to the North direction over short distances for several northernmost stations. The anisotropy pattern obtained from the analysis of the SKKS phases is the same as that from the SKS phases. However, when the SKS and SKKS phases sample at the edges of the VLVP, the measured anisotropy exhibits a very complex pattern. The obtained fast polarization directions change rapidly over a small distance, and they no longer correlate with stations; the measurements obtained from the SKS analysis also differ with those from the SKKS analysis. As the SKS and SKKS

  2. Adaptive neuro-fuzzy inference systems for semi-automatic discrimination between seismic events: a study in Tehran region

    Science.gov (United States)

    Vasheghani Farahani, Jamileh; Zare, Mehdi; Lucas, Caro

    2012-04-01

    Thisarticle presents an adaptive neuro-fuzzy inference system (ANFIS) for classification of low magnitude seismic events reported in Iran by the network of Tehran Disaster Mitigation and Management Organization (TDMMO). ANFIS classifiers were used to detect seismic events using six inputs that defined the seismic events. Neuro-fuzzy coding was applied using the six extracted features as ANFIS inputs. Two types of events were defined: weak earthquakes and mining blasts. The data comprised 748 events (6289 signals) ranging from magnitude 1.1 to 4.6 recorded at 13 seismic stations between 2004 and 2009. We surveyed that there are almost 223 earthquakes with M ≤ 2.2 included in this database. Data sets from the south, east, and southeast of the city of Tehran were used to evaluate the best short period seismic discriminants, and features as inputs such as origin time of event, distance (source to station), latitude of epicenter, longitude of epicenter, magnitude, and spectral analysis (fc of the Pg wave) were used, increasing the rate of correct classification and decreasing the confusion rate between weak earthquakes and quarry blasts. The performance of the ANFIS model was evaluated for training and classification accuracy. The results confirmed that the proposed ANFIS model has good potential for determining seismic events.

  3. Technology of research of hydroturbine unit work using seismic methods

    Science.gov (United States)

    Seleznev, V. S.; Liseikin, A. V.; Gromyko, P. V.; Soloviev, V. M.

    2013-05-01

    On August, 17, 2009 one of the most significant accident in hydropower engineering was happened at Sayano-Shushenskaya Hydroelectric Power Station. Specialists of Geophysical Survey SB RAS took part in the State Committee on investigation of the accident cause at Sayano-Shushenskaya HPS. It was determined, that the cause of the accident was a break of stud-bolts on the turbine cover. Why stud-bolts did not stand a load? There were assumptions that hydraulic shock provoked the accident. But, if it is so, seismic station "Cheremushky", situated in 4 km away from the HPS, should has a record of this event. First of all, investigating the record, got at the seismic station in the moment of the accident, it was determined that strength of seismic waves, recorded at the moment of the accident, did not exceed strength of waves got at trotyl explosion of 500 g at a distance to 4 km. The version of hydraulic shock was not proved. There were distinguished low-frequency oscillations and it was determined that the hydroturbine unit (HU) had been raised up more then 10 m in height for 10 sec. Analyzing the seismic station records during the period of more than a year before the accident and records of operating modes of different HU, there was determined that oscillations radiated by second (damaged) HU were approximately 1.5 times more intense than oscillations from all other HU. After the accident at Sayano-Shushenskaya HPS hydroturbine units were started in turns: at first there were started hydroturbine units of old construction (3, 4, 5, 6), then HP of new construction (1, 7, 8, 9). We installed 10 - 15 three-component seismic stations in different points around a HU and studied field of seismic oscillations from it's work. It was determined, that HU radiates a set of monochromatic oscillations divisible by speed of rotation equal to 2.381 Hz. Change of these signals amplitude is connected with change of HU operation modes. Research of changes in oscillations spectral

  4. Reflection seismic imaging of the upper crystalline crust for characterization of potential repository sites: Fine tuning the seismic source

    Energy Technology Data Exchange (ETDEWEB)

    Juhlin, C.; Palm, H.; Bergman, B. [Uppsala Univ. (Sweden). Dept. of Earth Sciences

    2001-09-01

    SKB is currently carrying out studies to determine which seismic techniques, and how, they will be used for investigations prior to and during the building of a high-level nuclear waste repository. Active seismic methods included in these studies are refraction seismics, reflection seismics, and vertical seismic profiling (VSP). The main goal of the active seismic methods is to locate fracture zones in the crystalline bedrock. Plans are to use longer reflection seismic profiles (3.4 km) in the initial stages of the site investigations. The target depth for these seismic profiles is 100-1500 m. Prior to carrying out the seismic surveys over actual candidate waste repository sites it has been necessary to carry out a number of tests to determine the optimum acquisition parameters. This report constitutes a summary of the tests carried out by Uppsala University. In addition, recommended acquisition and processing parameters are presented at the end of the report. A major goal in the testing has been to develop a methodology for acquiring high-resolution reflection seismic data over crystalline rock in as a cost effective manner as possible. Since the seismic source is generally a major cost in any survey, significant attention has been given to reducing the cost of the source. It was agreed upon early in the study that explosives were the best source from a data quality perspective and, therefore, only explosive source methods have been considered in this study. The charge size and shot hole dimension required to image the upper 1-1.5 km of bedrock is dependent upon the conditions at the surface. In this study two types of shot hole drilling methods have been employed depending upon whether the thickness of the loose sediments at the surface is greater or less than 0.5 m. The charge sizes and shot hole dimensions required are: Loose sediment thickness less than 0.5 m: 15 g in 90 cm deep 12 mm wide uncased shot holes. Loose sediment thickness greater than 0.5 m: 75 g

  5. The source parameters of 2013 Mw6.6 Lushan earthquake constrained with the restored local clipped seismic waveforms

    Science.gov (United States)

    Hao, J.; Zhang, J. H.; Yao, Z. X.

    2017-12-01

    We developed a method to restore the clipped seismic waveforms near epicenter using projection onto convex sets method (Zhang et al, 2016). This method was applied to rescue the local clipped waveforms of 2013 Mw 6.6 Lushan earthquake. We restored 88 out of 93 clipped waveforms of 38 broadband seismic stations of China Earthquake Networks (CEN). The epicenter distance of the nearest station to the epicenter that we can faithfully restore is only about 32 km. In order to investigate if the source parameters of earthquake could be determined exactly with the restored data, restored waveforms are utilized to get the mechanism of Lushan earthquake. We apply the generalized reflection-transmission coefficient matrix method to calculate the synthetic seismic records and simulated annealing method in inversion (Yao and Harkrider, 1983; Hao et al., 2012). We select 5 stations of CEN with the epicenter distance about 200km whose records aren't clipped and three-component velocity records are used. The result shows the strike, dip and rake angles of Lushan earthquake are 200o, 51o and 87o respectively, hereinafter "standard result". Then the clipped and restored seismic waveforms are applied respectively. The strike, dip and rake angles of clipped seismic waveforms are 184o, 53o and 72o respectively. The largest misfit of angle is 16o. In contrast, the strike, dip and rake angles of restored seismic waveforms are 198o, 51o and 87o respectively. It is very close to the "standard result". We also study the rupture history of Lushan earthquake constrained with the restored local broadband and teleseismic waves based on finite fault method (Hao et al., 2013). The result consists with that constrained with the strong motion and teleseismic waves (Hao et al., 2013), especially the location of the patch with larger slip. In real-time seismology, determining the source parameters as soon as possible is important. This method will help us to determine the mechanism of earthquake

  6. Station Set Residual: Event Classification Using Historical Distribution of Observing Stations

    Science.gov (United States)

    Procopio, Mike; Lewis, Jennifer; Young, Chris

    2010-05-01

    Analysts working at the International Data Centre in support of treaty monitoring through the Comprehensive Nuclear-Test-Ban Treaty Organization spend a significant amount of time reviewing hypothesized seismic events produced by an automatic processing system. When reviewing these events to determine their legitimacy, analysts take a variety of approaches that rely heavily on training and past experience. One method used by analysts to gauge the validity of an event involves examining the set of stations involved in the detection of an event. In particular, leveraging past experience, an analyst can say that an event located in a certain part of the world is expected to be detected by Stations A, B, and C. Implicit in this statement is that such an event would usually not be detected by Stations X, Y, or Z. For some well understood parts of the world, the absence of one or more "expected" stations—or the presence of one or more "unexpected" stations—is correlated with a hypothesized event's legitimacy and to its survival to the event bulletin. The primary objective of this research is to formalize and quantify the difference between the observed set of stations detecting some hypothesized event, versus the expected set of stations historically associated with detecting similar nearby events close in magnitude. This Station Set Residual can be quantified in many ways, some of which are correlated with the analysts' determination of whether or not the event is valid. We propose that this Station Set Residual score can be used to screen out certain classes of "false" events produced by automatic processing with a high degree of confidence, reducing the analyst burden. Moreover, we propose that the visualization of the historically expected distribution of detecting stations can be immediately useful as an analyst aid during their review process.

  7. Temporal variations of the fractal properties of seismicity in the western part of the north Anatolian fault zone: possible artifacts due to improvements in station coverage

    Directory of Open Access Journals (Sweden)

    A. O. Öncel

    1995-01-01

    Full Text Available Seismically-active fault zones are complex natural systems exhibiting scale-invariant or fractal correlation between earthquakes in space and time, and a power-law scaling of fault length or earthquake source dimension consistent with the exponent b of the Gutenberg-Richter frequency-magnitude relation. The fractal dimension of seismicity is a measure of the degree of both the heterogeneity of the process (whether fixed or self-generated and the clustering of seismic activity. Temporal variations of the b-value and the two-point fractal (correlation dimension Dc have been related to the preparation process for natural earthquakes and rock fracture in the laboratory These statistical scaling properties of seismicity may therefore have the potential at least to be sensitive short- term predictors of major earthquakes. The North Anatolian Fault Zone (NAFZ is a seismicallyactive dextral strike slip fault zone which forms the northern boundary of the westward moving Anatolian plate. It is splayed into three branches at about 31oE and continues westward toward the northern Aegean sea. In this study, we investigate the temporal variation of Dc and the Gutenberg-Richter b-value for seismicity in the western part of the NAFZ (including the northern Aegean sea for earthquakes of Ms > 4.5 occurring in the period between 1900 and 1992. b ranges from 0.6-1.6 and Dc from 0.6 to 1.4. The b-value is found to be weakly negatively correlated with Dc (r=-0.56. However the (log of event rate N is positively correlated with b, with a similar degree of statistical significance (r=0.42, and negatively correlated with Dc (r=-0.48. Since N increases dramatically with improved station coverage since 1970, the observed negative correlation between b and Dc is therefore more likely to be due to this effect than any underlying physical process in this case. We present this as an example of how man-made artefacts of recording can have similar statistical effects to

  8. Promoting seismology education through collaboration between university research scientists and school teachers

    Science.gov (United States)

    Brunt, M. R.; Ellins, K. K.; Boyd, D.; Mote, A. S.; Pulliam, J.; Frohlich, C. A.

    2012-12-01

    Participation in the NSF-sponsored Texas Earth and Space Science (TXESS) Revolution teacher professional development project paved the way for several teachers to receive educational seismometers and join the IRIS Seismograph in Schools program. This, in turn, has led to secondary school teachers working with university seismologists on research projects. Examples are the NSF-EarthScope SIEDCAR (Seismic Investigation of Edge Driven Convection Associated with the Rio Grande Rift) project; field studies to compile felt-reports for Texas earthquakes, some which may have been induced by human activities; and a seismic study of the Texas Gulf Coast to investigate ocean-continent transition processes along a passive margin. Such collaborations are mutually beneficial in nature. They help scientists to accomplish their research objectives, involve teachers and their students in the authentic, inquiry-based science, promote public awareness of such projects, and open the doors to advancement opportunities for those teachers involved. In some cases, bringing together research scientists and teachers results in collaborations that produce publishable research. In order to effectively integrate seismology research into 7-12 grade education, one of us (Brunt) established the Eagle Pass Junior High Seismology Team in connection with IRIS Seismograph in Schools, station EPTX (AS-1 seismograph), to teach students about earthquakes using authentic real-time data. The concept has sparked interest among other secondary teachers, leading to the creation of two similarly organized seismology teams: WPTX (Boyd, Williams Preparatory School, Dallas) and THTX (Mote, Ann Richards School for Young Women Leaders, Austin). Although the educational seismometers are basic instruments, they are effective educational tools. Seismographs in schools offer students opportunities to learn how earthquakes are recorded and how modern seismometers work, to collect and interpret seismic data, and to

  9. Aseismic foundation system for nuclear power stations

    International Nuclear Information System (INIS)

    Jolivet, F.; Richli, M.

    1977-01-01

    The aseismic foundation system, as described in this paper, is a new development, which makes it possible to build standard nuclear power stations in areas exposed to strong earthquakes. By adopting proven engineering concepts in design and construction of components, great advantages are achieved in the following areas: safety and reliability; efficiency; design schedule; cost. The need for an aseismic foundation system will arise more and more, as a large part of nuclear power station sites are located in highly seismic zones or must meet high intensity earthquake criteria due to the lack of historic data. (Auth.)

  10. Innovations in seismic tomography, their applications and induced seismic events in carbon sequestration

    Science.gov (United States)

    Li, Peng

    algorithm with the inclusion of full topography that is integrated from the Digital Elevation Model data. We present both synthetic and real data tests based on the compressional (P) wave arrival time data for Kilauea volcano in Hawai'i. A total of 33,768 events with 515,711 P-picks recorded by 35 stations at the Hawaiian Volcano Observatory are used in these tests. The comparison between the new and traditional methods based on the synthetic test shows that our new algorithm significantly improves the accuracy of the velocity model, especially at shallow depths. In the real data test, the P-wave velocity model of Kilauea shows some intriguing features. Velocity decrease from the surface to 2 km depth beneath Kilauea caldera indicates a state change of the basalt. Low velocity zones beneath Pu'u'O'o, Heiheiahulu and the Hilina fault system between 5 and 12 km are possible partial melting zones. High velocity anomalies are resolved below 6 km depth beneath the summit caldera, which may suggest the presence of consolidated gabbro-ultramafic cumulates. In the third work, we installed three broadband seismic stations (Test1, Test2 and Test3) in an Enhanced Oil Recovery field to monitor the potential seismic events associated with CO 2 injection. In the two years of continuous seismic data between October 2011 and October 2013, we observed a type of long duration (LD) events instead of typical micro earthquakes, with an average daily rate of 12. The LD events have the following characteristics: (1) their duration varies from ˜30 to ˜300 sec; (2) the amplitude changes smoothly from the beginning to the end of the LD event window; (3) they are local seismic events and were not recorded by regional seismic stations (e.g., ˜200 km away); (4) the waveforms are very different from those of typical earthquakes, but similar to volcanic tremors; (5) the frequency content is mainly concentrated between 0.5 and 6 Hz, which is similar to the frequency band of volcanic tremors; and (6

  11. Next Generation Polar Seismic Instrumentation Challenges

    Science.gov (United States)

    Parker, T.; Beaudoin, B. C.; Gridley, J.; Anderson, K. R.

    2011-12-01

    Polar region logistics are the limiting factor for deploying deep field seismic arrays. The IRIS PASSCAL Instrument Center, in collaboration with UNAVCO, designed and deployed several systems that address some of the logistical constraints of polar deployments. However, continued logistics' pressures coupled with increasingly ambitious science projects require further reducing the logistics required for deploying both summer and over winter stations. Our focus is to reduce station power requirements and bulk, thereby minimizing the time and effort required to deploy these arrays. We will reduce the weight of the battery bank by incorporating the most applicable new high energy-density battery technology. Using these batteries will require a completely new power management system along with an appropriate smart enclosure. The other aspect will be to integrate the digitizing system with the sensor. Both of these technologies should reduce the install time and shipping volume plus weight while reducing some instrument costs. We will also continue work on an effective Iridium telemetry solution for automated data return. The costs and limitations of polar deep-field science easily justifies a specialized development effort but pays off doubly in that we will continue to leverage the advancements in reduced logistics and increased performance for the benefit of low-latitude seismic research.

  12. EMERALD: A Flexible Framework for Managing Seismic Data

    Science.gov (United States)

    West, J. D.; Fouch, M. J.; Arrowsmith, R.

    2010-12-01

    The seismological community is challenged by the vast quantity of new broadband seismic data provided by large-scale seismic arrays such as EarthScope’s USArray. While this bonanza of new data enables transformative scientific studies of the Earth’s interior, it also illuminates limitations in the methods used to prepare and preprocess those data. At a recent seismic data processing focus group workshop, many participants expressed the need for better systems to minimize the time and tedium spent on data preparation in order to increase the efficiency of scientific research. Another challenge related to data from all large-scale transportable seismic experiments is that there currently exists no system for discovering and tracking changes in station metadata. This critical information, such as station location, sensor orientation, instrument response, and clock timing data, may change over the life of an experiment and/or be subject to post-experiment correction. Yet nearly all researchers utilize metadata acquired with the downloaded data, even though subsequent metadata updates might alter or invalidate results produced with older metadata. A third long-standing issue for the seismic community is the lack of easily exchangeable seismic processing codes. This problem stems directly from the storage of seismic data as individual time series files, and the history of each researcher developing his or her preferred data file naming convention and directory organization. Because most processing codes rely on the underlying data organization structure, such codes are not easily exchanged between investigators. To address these issues, we are developing EMERALD (Explore, Manage, Edit, Reduce, & Analyze Large Datasets). The goal of the EMERALD project is to provide seismic researchers with a unified, user-friendly, extensible system for managing seismic event data, thereby increasing the efficiency of scientific enquiry. EMERALD stores seismic data and metadata in a

  13. Crustal deformation and seismic measurements in the region of McDonald Observatory, West Texas. [Texas and Northern Chihuahua, Mexico

    Science.gov (United States)

    Dorman, H. J.

    1981-01-01

    The arrival times of regional and local earthquakes and located earthquakes in the Basin and Range province of Texas and in the adjacent areas of Chihuahua, Mexico from January 1976 to August 1980 at the UT'NASA seismic array are summarized. The August 1931 Texas earthquake is reevaluated and the seismicity and crustal structure of West Texas is examined. A table of seismic stations is included.

  14. Advances in seismic criteria to qualify structures, systems and components in operating reactors

    International Nuclear Information System (INIS)

    Manrique, M.A.; Bak, W.R.

    1989-01-01

    This paper describes improved seismic evaluation criteria and analysis methodologies used as part of the seismic reevaluation of San Onofre Nuclear Generating Station, Unit 1. The plant had originally been designed for 0.25 g ground acceleration and was required to be upgraded to a 0.67 g ground acceleration as part of the plant's Long Term Service Seismic Reevaluation Program. The application of the criteria and methods described in this paper to demonstrate the seismic capability of the plant resulted in efficient plant modifications with considerable cost savings to the plant owner. The NRC accepted these criteria and methods based on favorable results of reviews, audits and independent verification of the theories, bases and implementation procedures of the proposed criteria and analysis methods

  15. Cross-correlation analysis of 2012-2014 seismic events in Central-Northern Italy: insights from the geochemical monitoring network of Tuscany

    Science.gov (United States)

    Pierotti, Lisa; Facca, Gianluca; Gherardi, Fabrizio

    2015-04-01

    Since late 2002, a geochemical monitoring network is operating in Tuscany, Central Italy, to collect data and possibly identify geochemical anomalies that characteristically occur before regionally significant (i.e. with magnitude > 3) seismic events. The network currently consists of 6 stations located in areas already investigated in detail for their geological setting, hydrogeological and geochemical background and boundary conditions. All these stations are equipped for remote, continuous monitoring of selected physicochemical parameters (temperature, pH, redox potential, electrical conductivity), and dissolved concentrations of CO2 and CH4. Additional information are obtained through in situ discrete monitoring. Field surveys are periodically performed to guarantee maintenance and performance control of the sensors of the automatic stations, and to collect water samples for the determination of the chemical and stable isotope composition of all the springs investigated for seismic precursors. Geochemical continuous signals are numerically processed to remove outliers, monitoring errors and aseismic effects from seasonal and climatic fluctuations. The elaboration of smoothed, long-term time series (more than 200000 data available today for each station) allows for a relatively accurate definition of geochemical background values. Geochemical values out of the two-sigma relative standard deviation domain are inspected as possible indicators of physicochemical changes related to regional seismic activity. Starting on November 2011, four stations of the Tuscany network located in two separate mountainous areas of Northern Apennines separating Tuscany from Emilia-Romagna region (Equi Terme and Gallicano), and Tuscany from Emilia-Romagna and Umbria regions (Vicchio and Caprese Michelangelo), started to register anomalous values in pH and CO2 partial pressure (PCO2). Cross-correlation analysis indicates an apparent relationship between the most important seismic

  16. Single-Station Sigma for the Iranian Strong Motion Stations

    Science.gov (United States)

    Zafarani, H.; Soghrat, M. R.

    2017-11-01

    In development of ground motion prediction equations (GMPEs), the residuals are assumed to have a log-normal distribution with a zero mean and a standard deviation, designated as sigma. Sigma has significant effect on evaluation of seismic hazard for designing important infrastructures such as nuclear power plants and dams. Both aleatory and epistemic uncertainties are involved in the sigma parameter. However, ground-motion observations over long time periods are not available at specific sites and the GMPEs have been derived using observed data from multiple sites for a small number of well-recorded earthquakes. Therefore, sigma is dominantly related to the statistics of the spatial variability of ground motion instead of temporal variability at a single point (ergodic assumption). The main purpose of this study is to reduce the variability of the residuals so as to handle it as epistemic uncertainty. In this regard, it is tried to partially apply the non-ergodic assumption by removing repeatable site effects from total variability of six GMPEs driven from the local, Europe-Middle East and worldwide data. For this purpose, we used 1837 acceleration time histories from 374 shallow earthquakes with moment magnitudes ranging from M w 4.0 to 7.3 recorded at 370 stations with at least two recordings per station. According to estimated single-station sigma for the Iranian strong motion stations, the ratio of event-corrected single-station standard deviation ( Φ ss) to within-event standard deviation ( Φ) is about 0.75. In other words, removing the ergodic assumption on site response resulted in 25% reduction of the within-event standard deviation that reduced the total standard deviation by about 15%.

  17. Localization of short-range acoustic and seismic wideband sources: Algorithms and experiments

    Science.gov (United States)

    Stafsudd, J. Z.; Asgari, S.; Hudson, R.; Yao, K.; Taciroglu, E.

    2008-04-01

    We consider the determination of the location (source localization) of a disturbance source which emits acoustic and/or seismic signals. We devise an enhanced approximate maximum-likelihood (AML) algorithm to process data collected at acoustic sensors (microphones) belonging to an array of, non-collocated but otherwise identical, sensors. The approximate maximum-likelihood algorithm exploits the time-delay-of-arrival of acoustic signals at different sensors, and yields the source location. For processing the seismic signals, we investigate two distinct algorithms, both of which process data collected at a single measurement station comprising a triaxial accelerometer, to determine direction-of-arrival. The direction-of-arrivals determined at each sensor station are then combined using a weighted least-squares approach for source localization. The first of the direction-of-arrival estimation algorithms is based on the spectral decomposition of the covariance matrix, while the second is based on surface wave analysis. Both of the seismic source localization algorithms have their roots in seismology; and covariance matrix analysis had been successfully employed in applications where the source and the sensors (array) are typically separated by planetary distances (i.e., hundreds to thousands of kilometers). Here, we focus on very-short distances (e.g., less than one hundred meters) instead, with an outlook to applications in multi-modal surveillance, including target detection, tracking, and zone intrusion. We demonstrate the utility of the aforementioned algorithms through a series of open-field tests wherein we successfully localize wideband acoustic and/or seismic sources. We also investigate a basic strategy for fusion of results yielded by acoustic and seismic arrays.

  18. Southern Appalachian Regional Seismic Network

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, S.C.C.; Johnston, A.C.; Chiu, J.M. [Memphis State Univ., TN (United States). Center for Earthquake Research and Information

    1994-08-01

    The seismic activity in the southern Appalachian area was monitored by the Southern Appalachian Regional Seismic Network (SARSN) since late 1979 by the Center for Earthquake Research and Information (CERI) at Memphis State University. This network provides good spatial coverage for earthquake locations especially in east Tennessee. The level of activity concentrates more heavily in the Valley and Ridge province of eastern Tennessee, as opposed to the Blue Ridge or Inner Piedmont. The large majority of these events lie between New York - Alabama lineament and the Clingman/Ocoee lineament, magnetic anomalies produced by deep-seated basement structures. Therefore SARSN, even with its wide station spacing, has been able to define the essential first-order seismological characteristics of the Southern Appalachian seismic zone. The focal depths of the southeastern U.S. earthquakes concentrate between 8 and 16 km, occurring principally beneath the Appalachian overthrust. In cross-sectional views, the average seismicity is shallower to the east beneath the Blue Ridge and Piedmont provinces and deeper to the west beneath the Valley and Ridge and the North American craton. Results of recent focal mechanism studies by using the CERI digital earthquake catalog between October, 1986 and December, 1991, indicate that the basement of the Valley and Ridge province is under a horizontal, NE-SW compressive stress. Right-lateral strike-slip faulting on nearly north-south fault planes is preferred because it agrees with the trend of the regional magnetic anomaly pattern.

  19. Southern Appalachian Regional Seismic Network

    International Nuclear Information System (INIS)

    Chiu, S.C.C.; Johnston, A.C.; Chiu, J.M.

    1994-08-01

    The seismic activity in the southern Appalachian area was monitored by the Southern Appalachian Regional Seismic Network (SARSN) since late 1979 by the Center for Earthquake Research and Information (CERI) at Memphis State University. This network provides good spatial coverage for earthquake locations especially in east Tennessee. The level of activity concentrates more heavily in the Valley and Ridge province of eastern Tennessee, as opposed to the Blue Ridge or Inner Piedmont. The large majority of these events lie between New York - Alabama lineament and the Clingman/Ocoee lineament, magnetic anomalies produced by deep-seated basement structures. Therefore SARSN, even with its wide station spacing, has been able to define the essential first-order seismological characteristics of the Southern Appalachian seismic zone. The focal depths of the southeastern U.S. earthquakes concentrate between 8 and 16 km, occurring principally beneath the Appalachian overthrust. In cross-sectional views, the average seismicity is shallower to the east beneath the Blue Ridge and Piedmont provinces and deeper to the west beneath the Valley and Ridge and the North American craton. Results of recent focal mechanism studies by using the CERI digital earthquake catalog between October, 1986 and December, 1991, indicate that the basement of the Valley and Ridge province is under a horizontal, NE-SW compressive stress. Right-lateral strike-slip faulting on nearly north-south fault planes is preferred because it agrees with the trend of the regional magnetic anomaly pattern

  20. Borehole P- and S-wave velocity at thirteen stations in Southern California

    Science.gov (United States)

    Gibbs, James F.; Boore, David M.; Tinsley, John C.; Mueller, Charles S.

    2001-01-01

    The U.S. Geological Survey (USGS), as part of a program to acquire seismic velocity data at locations of strong-ground motion in earthquakes (e.g., Gibbs et al., 2000), has investigated thirteen additional sites in the Southern California region. Of the thirteen sites, twelve are in the vicinity of Whittier, California, and one is located in San Bernardino, California. Several deployments of temporary seismographs were made after the Whittier Narrows, California earthquake of 1 October 1987 (Mueller et al., 1988). A deployment, between 2 October and 9 November 1987, was the motivation for selection of six of the drill sites. Temporary portable seismographs at Hoover School (HOO), Lincoln School (LIN), Corps of Engineers Station (NAR), Olive Junior High School (OLV), Santa Anita Golf Course (SAG), and Southwestern Academy (SWA) recorded significant aftershock data. These portable sites, with the exception of Santa Anita Golf Course, were co-sited with strong-motion recorders. Stations at HOO, Lincoln School Whittier (WLB), Saint Paul High School (STP), Alisos Adult School (EXC), Cerritos College Gymnasium (CGM), Cerritos College Physical Science Building (CPS), and Cerritos College Police Building (CPB) were part of an array of digital strong-motion stations deployed from "bedrock" in Whittier to near the deepest part of the Los Angeles basin in Norwalk. Although development and siting of this new array (partially installed at the time of this writing) was generally motivated by the Whittier Narrows earthquake, these new sites (with the exception of HOO) were not part of any Whittier Narrows aftershock deployments. A similar new digital strong-motion site was installed at the San Bernardino Fire Station during the same time frame. Velocity data were obtained to depths of about 90 meters at two sites, 30 meters at seven sites, and 18 to 25 meters at four sites. Lithology data from the analysis of cuttings and samples was obtained from the two 90-meter deep holes and

  1. REGIONAL SEISMIC AMPLITUDE MODELING AND TOMOGRAPHY FOR EARTHQUAKE-EXPLOSION DISCRIMINATION

    Energy Technology Data Exchange (ETDEWEB)

    Walter, W R; Pasyanos, M E; Matzel, E; Gok, R; Sweeney, J; Ford, S R; Rodgers, A J

    2008-07-08

    We continue exploring methodologies to improve earthquake-explosion discrimination using regional amplitude ratios such as P/S in a variety of frequency bands. Empirically we demonstrate that such ratios separate explosions from earthquakes using closely located pairs of earthquakes and explosions recorded on common, publicly available stations at test sites around the world (e.g. Nevada, Novaya Zemlya, Semipalatinsk, Lop Nor, India, Pakistan, and North Korea). We are also examining if there is any relationship between the observed P/S and the point source variability revealed by longer period full waveform modeling (e. g. Ford et al 2008). For example, regional waveform modeling shows strong tectonic release from the May 1998 India test, in contrast with very little tectonic release in the October 2006 North Korea test, but the P/S discrimination behavior appears similar in both events using the limited regional data available. While regional amplitude ratios such as P/S can separate events in close proximity, it is also empirically well known that path effects can greatly distort observed amplitudes and make earthquakes appear very explosion-like. Previously we have shown that the MDAC (Magnitude Distance Amplitude Correction, Walter and Taylor, 2001) technique can account for simple 1-D attenuation and geometrical spreading corrections, as well as magnitude and site effects. However in some regions 1-D path corrections are a poor approximation and we need to develop 2-D path corrections. Here we demonstrate a new 2-D attenuation tomography technique using the MDAC earthquake source model applied to a set of events and stations in both the Middle East and the Yellow Sea Korean Peninsula regions. We believe this new 2-D MDAC tomography has the potential to greatly improve earthquake-explosion discrimination, particularly in tectonically complex regions such as the Middle East. Monitoring the world for potential nuclear explosions requires characterizing seismic

  2. EMERALD: Coping with the Explosion of Seismic Data

    Science.gov (United States)

    West, J. D.; Fouch, M. J.; Arrowsmith, R.

    2009-12-01

    The geosciences are currently generating an unparalleled quantity of new public broadband seismic data with the establishment of large-scale seismic arrays such as the EarthScope USArray, which are enabling new and transformative scientific discoveries of the structure and dynamics of the Earth’s interior. Much of this explosion of data is a direct result of the formation of the IRIS consortium, which has enabled an unparalleled level of open exchange of seismic instrumentation, data, and methods. The production of these massive volumes of data has generated new and serious data management challenges for the seismological community. A significant challenge is the maintenance and updating of seismic metadata, which includes information such as station location, sensor orientation, instrument response, and clock timing data. This key information changes at unknown intervals, and the changes are not generally communicated to data users who have already downloaded and processed data. Another basic challenge is the ability to handle massive seismic datasets when waveform file volumes exceed the fundamental limitations of a computer’s operating system. A third, long-standing challenge is the difficulty of exchanging seismic processing codes between researchers; each scientist typically develops his or her own unique directory structure and file naming convention, requiring that codes developed by another researcher be rewritten before they can be used. To address these challenges, we are developing EMERALD (Explore, Manage, Edit, Reduce, & Analyze Large Datasets). The overarching goal of the EMERALD project is to enable more efficient and effective use of seismic datasets ranging from just a few hundred to millions of waveforms with a complete database-driven system, leading to higher quality seismic datasets for scientific analysis and enabling faster, more efficient scientific research. We will present a preliminary (beta) version of EMERALD, an integrated

  3. Methodology and results of a space station education pilot programme in the primary school

    Science.gov (United States)

    Mirra, G.; Mirra, C.

    Potential users of the Space Station Freedom are now still in the Primary School. Subject studies 1 have shown that a robust familiarization programme has to be developed in order to increase public awareness on the microgravity environment and its capabilities to perform unique science. At the same time, several surveys 2 have demonstrated that elementary school students are showing the greatest interest and enthusiasm in space related activities among all school students. With these boundary conditions, a pilot programme, aimed at verifying the capabilities of young primary school pupils (aged between 10 and 12) in understanding why one performs research in space, has been conceived. In order to overcome the lack of space training of school teachers, an expert in space operations joined a group of elementary teachers to activate this program: merging the necessary didactic and technical capabilities. Consequently, the aim of the program becomes two folded: •generate critical thinking and problem solving capacities as well as inventiveness in children making them aware on the use of space to improve life on Earth. •identify the key issues for the definition of a robust space utilization educational programme. The programme has been managed by MARS Center. the Italian User Support Center for the Space Station utilization, and the institute "Speranzas" in the nearby of Naples, Italy. MARS Center, in particular, is responsible towards the national agency ASI, Agenzia Spaziale Italiana, of the execution of the promotional activity towards all the possible target groups: young students are among these groups. This programme started in late 1992 and is currently ongoing. The objective of this paper is to provide a description of the methodology and the reasons of such a programme with a snapshot on the preliminary results and future trends. Means used as supporting tools, such as films, posters and role plays are herein depicted as well as statistics on the pupils

  4. Central Italy magnetotelluric investigation. Structures and relations to seismic events: analysis of initial data

    Directory of Open Access Journals (Sweden)

    J. Marianiuk

    1996-06-01

    Full Text Available A scientific collaboration between the Warsaw Academy of Science, (Poland and the National Institute of Geophysics (Italy, gave rise to the installation of few stations for the long term measurement of magnetotelluric fields in central Italy. The selection of investigation sites was determined by the individual seismic interest of each location. The project began in the summer of 1991, with the installation of 2 magnetotelluric stations in the province of Isernia, (Collemeluccio and Montedimezzo. In 1992, 2 more stations became operative, one in the province of Rieti, (Fassinoro, the other in the province of L'Aquila, (S. Vittoria. For the purpose of this project, the magnetic observatory in L'Aquila was also equipped with electric lines, for the measurement of the telluric field. The aim of the analysis here presented, is to show that is possible to follow the temporal evolution of magnetotelluric characteristic parameters. At Collemeluccio this evolution was compared with the seismic released energy for events recorded within the study area.

  5. First Quarter Hanford Seismic Report for Fiscal Year 2009

    Energy Technology Data Exchange (ETDEWEB)

    Rohay, Alan C.; Sweeney, Mark D.; Hartshorn, Donald C.; Clayton, Ray E.; Devary, Joseph L.

    2009-03-15

    The Hanford Seismic Assessment Program (HSAP) provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network for the U.S. Department of Energy and its contractors. The HSAP is responsible for locating and identifying sources of seismic activity and monitoring changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, natural phenomena hazards assessments, and engineering design and construction. In addition, the HSAP works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The Hanford Seismic Network and the Eastern Washington Regional Network consist of 44 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Assessment Team. This includes three recently acquired Transportable Array stations located at Cold Creek, Didier Farms, and Phinney Hill. For the Hanford Seismic Network, ten local earthquakes were recorded during the first quarter of fiscal year 2009. All earthquakes were considered as “minor” with magnitudes (Mc) less than 1.0. Two earthquakes were located at shallow depths (less than 4 km), most likely in the Columbia River basalts; five earthquakes at intermediate depths (between 4 and 9 km), most likely in the sub-basalt sediments); and three earthquakes were located at depths greater than 9 km, within the basement. Geographically, four earthquakes occurred in known swarm areas and six earthquakes were classified as random events.

  6. First Quarter Hanford Seismic Report for Fiscal Year 1999

    Energy Technology Data Exchange (ETDEWEB)

    DC Hartshorn; SP Reidel; AC Rohay

    1999-05-26

    Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the U.S. Department of Energy and its contractors. They also locate and identify sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (EWRN) consists of 42 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. The operational rate for the first quarter of FY99 for stations in the HSN was 99.8%. There were 121 triggers during the first quarter of fiscal year 1999. Fourteen triggers were local earthquakes; seven (50%) were in the Columbia River Basalt Group, no earthquakes occurred in the pre-basalt sediments, and seven (50%) were in the crystalline basement. One earthquake (7%) occurred near or along the Horn Rapids anticline, seven earthquakes (50%) occurred in a known swarm area, and six earthquakes (43%) were random occurrences. No earthquakes triggered the Hanford Strong Motion Accelerometer during the first quarter of FY99.

  7. Full scale model studies of nuclear power stations for earthquake resistance

    International Nuclear Information System (INIS)

    Kirillov, A.P.; Ambriashvili, Ju. K.; Kozlov, A.V.

    Behaviour of nuclear power plants and its equipments under seismic action is not well understood. In the absence of well established method for aseismic deisgn of nuclear power plants and its equipments, it is necessary to carry out experimental investigations on models, fragments and full scale structures. The present study includes experimental investigations of different scale models and on existing nuclear power stations under impulse and explosion effects simulating seismic loads. The experimental work was aimed to develop on model test procedure for nuclear power station and the evaluation of the possible range of dynamic stresses in structures and pipe lines. The results of full-scale investigations of the nuclear reactor show a good agreement of dynamic characteristics of the model and the prototype. The study confirms the feasibility of simulation of model for nuclear power plants. (auth.)

  8. A Dense Small-Scale Seismic Network in the Ngorongoro Conservation Area (Northern Tanzania)

    Science.gov (United States)

    Parisi, L.; Lombardo, L.; Rodriguez-Mustafa, M.; Mai, P. M.

    2017-12-01

    A temporary deployment consisting of sixteen broadband seismic stations is conducted for the first time in the Ngorongoro Conservation Area (NCA, Northern Tanzania), located at the boundary between the Tanzanian Craton and East African Rift. A deep knowledge of the faulting systems and tectonics of the area is needed to better understand the contribution of the synsedimentary faults to the deposition of the Olduvai and surrounding basins affecting the landscapes of the Homo Habilis first settlements. Complex fault systems have been mapped in the field but their connection, especially at depth, is not well known. A first batch of ten instruments was installed in June 2016. In June 2017 two stations were dismissed and a second batch of six stations was installed in new locations. The current network of fourteen stations will record until May 2018. Stations are equipped with Nanometrics Trillium Compact Posthole 120 s sensor and Centaur digitiser recording continuously at 200 Hz. The whole network covers 1400 km2 and station interspace ranges from 8 to 15 km. We analyse probabilistic power spectra densities of the seismic noise to obtain insights of its origin and test the performances of the stations. Although factories do not exist in the area and most of the stations are far from roads, ambient noise in the range 0.01 - 1 s is relatively high (between -120 dB and -100dB at 0.1 s) probably because of the abundance of livestock living in the NCA. Ambient noise in the period range 1 - 10 s (secondary microseisms) decreases from east to west. Although the main source of the microseisms is located in the Indian Ocean (east of the study area), a contribution from the low period tremors coming from the nearby active volcano Ol Doinyo Lengai (north-east of the study area) is expected. Whereas the longer period noise (10 - 100 s) is very low in the vertical component seismograms, it is higher than the high noise model in the horizontal components for most of the stations

  9. Extreme loads seismic testing of conduit systems

    International Nuclear Information System (INIS)

    Howard, G.E.; Ibanez, P.; Harrison, S.; Shi, Z.T.

    1991-01-01

    Rigid steel conduit (thin-wall tubes with threaded connections) containing electrical cabling are a common feature in nuclear power plants. Conduit systems are in many cases classified in U.S.A. practice as Seismic Category I structures. this paper summarizes results and others aspects of a dynamic test program conducted to investigate conduit systems seismic performance under three-axis excitation for designs representative at a nuclear power plant sited near Ft. Worth, Texas (a moderate seismic zone), with a Safe Shutdown Earthquake (SSE) of 0.12 g. Test specimens where subjected to postulated seismic events, including excitation well in excess of Safe Shutdown Earthquake events typical for U.S.A. nuclear power stations. A total of 18 conduit systems of 9-meter nominal lengths were shake table mounted and subjected to a variety of tests. None of the specimens suffered loss of load capacity when subjected to a site-enveloping Safe Shutdown Earthquake (SSE). Clamp/attachment hardware failures only began to occur when earthquake input motion was scaled upward to minimum values of 2.3-4.6 times site enveloping SSE response spectra. Tensile and/or shear failure of clamp attachment bolts or studs was the failure mode in all case in which failure was induced. (author)

  10. Overview of seismic resistant design of Indian Nuclear Power Plants

    International Nuclear Information System (INIS)

    Sharma, G.K.; Hawaldar, R.V.K.P.; Vinod Kumar

    2007-01-01

    Safe operation of a Nuclear Power Plant (NPP) is of utmost importance. NPPs consist of various Structure, System and Equipment (SS and E) that are designed to resist the forces generated due to a natural phenomenon like earthquake. An earthquake causes severe oscillatory ground motion of short duration. Seismic resistant design of SS and E calls for evaluation of effect of severe ground shaking for assuring the structural integrity and operability during and after the occurrence of earthquake event. Overall exercise is a multi-disciplinary approach. First of standardized 220 MWe design reactor is Narora Atomic Power Station. Seismic design was carried out as per state of art then, for the first time. The twelve 220 MWe reactors and two 540 MWe reactors designed since 1975 have been seismically qualified for the earthquake loads expected in the region. Seismic design of 700 MWe reactor is under advanced stage of finalization. Seismic re-evaluation of six numbers of old plants has been completed as per latest state of art. Over the years, expertise have been developed at Nuclear Power Corporation of India Limited, Bhabha Atomic Research Centre, prominent educational institutes, research laboratories and engineering consultants in the country in the area of seismic design, analysis and shake table testing. (author)

  11. High Resolution Vertical Seismic Profile from the Chicxulub IODP/ICDP Expedition 364 Borehole: Wave Speeds and Seismic Reflectivity.

    Science.gov (United States)

    Nixon, C.; Kofman, R.; Schmitt, D. R.; Lofi, J.; Gulick, S. P. S.; Christeson, G. L.; Saustrup, S., Sr.; Morgan, J. V.

    2017-12-01

    We acquired a closely-spaced vertical seismic profile (VSP) in the Chicxulub K-Pg Impact Crater drilling program borehole to calibrate the existing surface seismic profiles and provide complementary measurements of in situ seismic wave speeds. Downhole seismic records were obtained at spacings ranging from 1.25 m to 5 m along the borehole from 47.5 m to 1325 mwsf (meters wireline below sea floor) (Fig 1a) using a Sercel SlimwaveTM geophone chain (University of Alberta). The seismic source was a 30/30ci Sercel Mini GI airgun (University of Texas), fired a minimum of 5 times per station. Seismic data processing used a combination of a commercial processing package (Schlumberger's VISTA) and MatlabTM codes. The VSP displays detailed reflectivity (Fig. 1a) with the strongest reflection seen at 600 mwsf (280 ms one-way time), geologically corresponding to the sharp contact between the post-impact sediments and the target peak ring rock, thus confirming the pre-drilling interpretations of the seismic profiles. A two-way time trace extracted from the separated up-going wavefield matches the major reflection both in travel time and character. In the granitic rocks that form the peak ring of the Chicxulub impact crater, we observe P-wave velocities of 4000-4500 m/s which are significantly less than the expected values of granitoids ( 6000 m/s) (Fig. 1b). The VSP measured wave speeds are confirmed against downhole sonic logging and in laboratory velocimetry measurements; these data provide additional evidence that the crustal material displaced by the impact experienced a significant amount of damage. Samples and data provided by IODP. Samples can be requested at http://web.iodp.tamu.edu/sdrm after 19 October 2017. Expedition 364 was jointly funded by ECORD, ICDP, and IODP with contributions and logistical support from the Yucatan State Government and UNAM. The downhole seismic chain and wireline system is funded by grants to DRS from the Canada Foundation for Innovation and

  12. Data transmission from seismic stations via network AGNES using GSM-GPRS technology

    Czech Academy of Sciences Publication Activity Database

    Knejzlík, Jaromír

    2004-01-01

    Roč. 1, č. 1 (2004), s. 73-76 ISSN 1211-1910. [Mining and Environmental geophysics/29./. Sedmihorky, 00.06.2003] R&D Projects: GA ČR GA205/01/0480 Institutional research plan: CEZ:AV0Z3086906 Keywords : seismic data transmission * GMS * GPRS Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  13. Seismic tomography of Basse-Terre volcanic island, Guadeloupe, Lesser Antilles, using earthquake travel times and noise correlations

    Science.gov (United States)

    Barnoud, Anne; Coutant, Olivier; Bouligand, Claire; Massin, Frédérick; Stehly, Laurent

    2015-04-01

    We image the volcanic island of Basse-Terre, Guadeloupe, Lesser Antilles, using both earthquake travel times and noise correlations. (1) A new earthquake catalog was recently compiled for the Lesser Antilles by the CDSA/OVSG/IPGP (Massin et al., EGU General Assembly 2014) and allows us to perform classical travel time tomography to obtain smooth 3D body wave velocity models. The geometrical configuration of the volcanic arc controls the resolution of the model in our zone of interest. (2) Surface wave tomography using noise correlations was successfully applied to volcanoes (Brenguier et al., Geophys. Res. Lett. 2007). We use seismic noise recorded at 16 broad-band stations and 9 short-period stations from Basse-Terre over a period of six years (2007-2012). For each station pair, we extract a dispersion curve from the noise correlation to get surface wave velocity models. The inversion of the dispersion curves produces a 3D S-wave velocity model of the island. The spatial distribution of seismic stations accross the island is highly heterogeneous, leading to higher resolution near the dome of the Soufrière of Guadeloupe volcano. Resulting velocity models are compared with densities obtained by 3D inversion of gravimetric data (Barnoud et al., AGU Fall Meeting 2013). Further work should include simultaneous inversion of seismic and gravimetric datasets to overcome resolution limitations.

  14. A joint program for seismographic station operations in the Republic of Kazakstan

    International Nuclear Information System (INIS)

    Kim, W.Y.; Belyashova, N.N.; Richards, P.G.

    1998-01-01

    In this paper there are examples of seismic signals recorded at the stations operated jointly by the Kazakhstan National Nuclear Centre and Lamont-Doherty Earth Observatory of Columbia University. Also the way the stations can be used to interpret the natural (earthquake) and and anthropogenic (explosion) sources from which the signals originated is shown. Examples include nuclear explosions carried out by China, India and Pakistan in recent years and months

  15. Seismic simulation and functional performance evaluation of a safety related, seismic category I control room emergency air cleaning system

    International Nuclear Information System (INIS)

    Manley, D.K.; Porco, R.D.; Choi, S.H.

    1985-01-01

    Under a nuclear contract MSA was required to design, manufacture, seismically test and functionally test a complete Safety Related, Seismic Category I, Control Room Emergency Air Cleaning System before shipment to the Yankee Atomic Electric Company, Yankee Nuclear Station in Rowe, Massachusetts. The installation of this system was required to satisfy the NRC requirements of NUREG-0737, Section III, D.3.4, ''Control Room Habitability''. The filter system tested was approximately 3 ft. wide by 8 ft. high by 18 ft. long and weighed an estimated 8300 pounds. It had a design flow rate of 3000 SCFM and contained four stages of filtration - prefilters, upstream and downstream HEPA filters and Type II sideload charcoal adsorber cells. The filter train design followed the guidelines set forth by ANSI/ASME N509-1980. Seismic Category I Qualification Testing consisted of resonance search testing and triaxial random multifrequency testing. In addition to ANSI/ASME N510-1980 testing, triaxial response accelerometers were placed at specific locations on designated prefilters, HEPA filters, charcoal adsorbers and test canisters along with accelerometers at the corresponding filter seal face locations. The purpose of this test was to demonstrate the integrity of the filters, filter seals, and monitor seismic response levels which is directly related to the system's ability to function during a seismic occurrence. The Control Room Emergency Air Cleaning System demonstrated the ability to withstand the maximum postulated earthquake for the plant site by remaining structurally sound and functional

  16. Earthquake Monitoring: SeisComp3 at the Swiss National Seismic Network

    Science.gov (United States)

    Clinton, J. F.; Diehl, T.; Cauzzi, C.; Kaestli, P.

    2011-12-01

    The Swiss Seismological Service (SED) has an ongoing responsibility to improve the seismicity monitoring capability for Switzerland. This is a crucial issue for a country with low background seismicity but where a large M6+ earthquake is expected in the next decades. With over 30 stations with spacing of ~25km, the SED operates one of the densest broadband networks in the world, which is complimented by ~ 50 realtime strong motion stations. The strong motion network is expected to grow with an additional ~80 stations over the next few years. Furthermore, the backbone of the network is complemented by broadband data from surrounding countries and temporary sub-networks for local monitoring of microseismicity (e.g. at geothermal sites). The variety of seismic monitoring responsibilities as well as the anticipated densifications of our network demands highly flexible processing software. We are transitioning all software to the SeisComP3 (SC3) framework. SC3 is a fully featured automated real-time earthquake monitoring software developed by GeoForschungZentrum Potsdam in collaboration with commercial partner, gempa GmbH. It is in its core open source, and becoming a community standard software for earthquake detection and waveform processing for regional and global networks across the globe. SC3 was originally developed for regional and global rapid monitoring of potentially tsunamagenic earthquakes. In order to fulfill the requirements of a local network recording moderate seismicity, SED has tuned configurations and added several modules. In this contribution, we present our SC3 implementation strategy, focusing on the detection and identification of seismicity on different scales. We operate several parallel processing "pipelines" to detect and locate local, regional and global seismicity. Additional pipelines with lower detection thresholds can be defined to monitor seismicity within dense subnets of the network. To be consistent with existing processing

  17. The Iquique 2014 sequence: understanding its nucleation and propagation from the seismicity evolution

    Science.gov (United States)

    Fuenzalida, A.; Rietbrock, A.; Woollam, J.; Tavera, H.; Ruiz, S.

    2017-12-01

    The Northern Chile and Southern Peru region is well known for its high seismic hazard due to the lack of recent major ruptures along long segments of the subduction interface. For this reason the 2014 Iquique Mw 8.1 earthquake that occurred in the Northern Chile seismic gap was expected and high quality seismic and geodetic networks were operating at the time of the event recording the precursory phase of a mega-thrust event with unprecedented detail. In this study we used seismic data collected during the 2014 Iquique sequence to generate a detailed earthquake catalogue. This catalogue consists of more than 15,000 events identified in Northern Chile during the period between 1/3/14 and 31/5/14 and provides full coverage of the immediate foreshock sequence, the main-shock and early after-shock series. The initial catalogue was obtained by automatic data processing and only selecting events with at least two associate S phases to improve the reliability of initial locations. Subsequently, this subset of events was automatically processed again using an optimized STA/LTA triggering algorithm for both P and S-waves and constraining the detection times by estimated arrival times at each station calculated for the preliminary locations. Finally, all events were relocated using a recently developed 1D velocity model and associated station corrections. For events Mw 4 or larger that occurred between the 15/3/14 and 10/04/14, we estimated it regional moment tensor by full-waveform inversion. Our results confirm the seismic activation of the upper plate during the foreshock sequence, as well highlight a crustal activity on the fore-arc during the aftershock series. The seismicity distribution was compared to the previous inter-seismic coupling studies obtained in the region, in which we observe interplay between high and low coupling areas, which are correlated to the seismicity rate. The spatial distribution of the seismicity and the complexities on the mechanisms observed

  18. DEPENDENCE OF DISTRIBUTION FUNCTION OF COMMERCIAL DAMAGES DUE TO POSSIBLE EARTHQUAKES ON THE CLASS OF SEISMIC RESISTANCE OF A BUILDING

    OpenAIRE

    Hanzada R. Zajnulabidova; Alexander M. Uzdin; Tatiana M. Chirkst

    2017-01-01

    Abstract. Objectives To determine the damage probability of earthquakes of different intensities on the example of a real projected railway station building having a framework design scheme based on the density function of damage distribution. Methods Uncertainty, always existing in nature, invalidates a deterministic approach to the assessment of territorial seismic hazards and, consequently, seismic risk. In this case, seismic risk assessment can be carried out on a probabilistic basis. Thu...

  19. Swedish National Seismic Network (SNSN). A short report on recorded earthquakes during the fourth quarter of the year 2010

    Energy Technology Data Exchange (ETDEWEB)

    Boedvarsson, Reynir (Uppsala Univ. (Sweden), Dept. of Earth Sciences)

    2011-01-15

    According to an agreement with Swedish Nuclear Fuel and Waste Management Company (SKB) and Uppsala Univ., the Dept. of Earth Sciences has continued to carry out observations of seismic events at seismic stations within the Swedish National Seismic Network (SNSN). This short report gives brief information about the recorded seismicity during October through December 2010. The Swedish National Seismic Network consists of 62 stations. During October through December, 2,241 events were located whereof 158 are estimated as real earthquakes, 1,457 are estimated as explosions, 444 are induced earthquakes in the vicinity of the mines in Kiruna and Malmberget and 182 events are still considered as uncertain but these are most likely explosions and are mainly located outside the network. One earthquake had a magnitude above M{sub L} = 2.0 during the period. In November one earthquake was located 13 km SW of Haernoesand with a magnitude of M{sub L} = 2.1. The largest earthquake in October had a magnitude of M{sub L} = 1.7 and was located 12 km NE of Eksjoe and in December an earthquake with a magnitude of M{sub L} = 1.8 was located 19 km north of Motala

  20. Statistical Seismology and Induced Seismicity

    Science.gov (United States)

    Tiampo, K. F.; González, P. J.; Kazemian, J.

    2014-12-01

    While seismicity triggered or induced by natural resources production such as mining or water impoundment in large dams has long been recognized, the recent increase in the unconventional production of oil and gas has been linked to rapid rise in seismicity in many places, including central North America (Ellsworth et al., 2012; Ellsworth, 2013). Worldwide, induced events of M~5 have occurred and, although rare, have resulted in both damage and public concern (Horton, 2012; Keranen et al., 2013). In addition, over the past twenty years, the increase in both number and coverage of seismic stations has resulted in an unprecedented ability to precisely record the magnitude and location of large numbers of small magnitude events. The increase in the number and type of seismic sequences available for detailed study has revealed differences in their statistics that previously difficult to quantify. For example, seismic swarms that produce significant numbers of foreshocks as well as aftershocks have been observed in different tectonic settings, including California, Iceland, and the East Pacific Rise (McGuire et al., 2005; Shearer, 2012; Kazemian et al., 2014). Similarly, smaller events have been observed prior to larger induced events in several occurrences from energy production. The field of statistical seismology has long focused on the question of triggering and the mechanisms responsible (Stein et al., 1992; Hill et al., 1993; Steacy et al., 2005; Parsons, 2005; Main et al., 2006). For example, in most cases the associated stress perturbations are much smaller than the earthquake stress drop, suggesting an inherent sensitivity to relatively small stress changes (Nalbant et al., 2005). Induced seismicity provides the opportunity to investigate triggering and, in particular, the differences between long- and short-range triggering. Here we investigate the statistics of induced seismicity sequences from around the world, including central North America and Spain, and

  1. Multi-parameter observations in the Ibero-Moghrebian region: the Western Mediterranean seismic network (WM) and ROA GPS geodynamic network

    Science.gov (United States)

    Pazos, Antonio; Martín Davila, José; Buforn, Elisa; Gárate Pasquín, Jorge; Catalán Morollón, Manuel; Hanka, Winfried; Udías, Agustín.; Benzzeghoud, Mourad; Harnafi, Mimoun

    2010-05-01

    The plate boundary between Eurasia and Africa plates crosses the called "Ibero-Maghrebian" region from the San Vicente Cape (SW Portugal) to Tunisia including the South of Iberia, Alboran Sea, and northern Morocco and Algeria. In this area, the convergence, with a low rate, is accommodated over a wide and diffuse deformation zone, characterized by a significant and widespread moderate seismic activity [Buforn et al., 1995], and the occurrence of large earthquakes is separated by long time intervals. Since more than hundred years ago San Fernando Naval Observatory (ROA), in collaboration with other Institutes, has deployed different geophysical and geodetic equipment in the Southern Spain - North-western Africa area in order to study this broad deformation zone. Currently a Broad Band seismic net (Western Mediterranean, WM net) is deployed, in collaboration with other institutions, around the Gulf of Cádiz and the Alboran sea, with stations in the South of Iberia and in North Africa (at Spanish places and Morocco), together with the seismic stations a permanent geodetic GPS net is co-installed at the same sites. Also, other geophysical instruments have been installed: a Satellite Laser Ranging (SLR) station at San Fernando Observatory Headquarter, a Geomagnetic Observatory in Cádiz bay area and some meteorological stations. These networks have been recently improved with the deployment of a new submarine and on-land geophysical observatory in the Alboran island (ALBO Observatory), where a permanent GPS, a meteorological station were installed on land and a permanent submarine observatory in 50 meters depth was also deploy in last October (with a broad band seismic sensor, a 3 C accelerometer and a DPG). This work shows the present status and the future plans of these networks and some results.

  2. Seismic safety margins research program. Project I SONGS 1 AFWS Project

    International Nuclear Information System (INIS)

    Chuang, T.Y.; Smith, P.D.; Dong, R.G.; Bernreuter, D.L.; Bohn, M.P.; Cummings, G.E.; Wells, J.E.

    1981-01-01

    The seismic qualification requirements of auxiliary feedwater systems (AFWS) of Pressurized Water Reactors (PWR) were developed over a number of years. These are formalized in the publication General Design Criteria (Appendix A to 10CFR50). The full recognition of the system as an engineered safety feature did not occur until publication of the Standard Review Plan (1975). Efforts to determine how to backfit seismic requirements to earlier plants has been undertaken primarily in the Systematic Evaluation Program (SEP) for a limited number of operating reactors. Nuclear Reactor Research (RES) and NRR have requested LLNL to perform a probabilistic study on the AFWS of San Onofre Nuclear Generating Station (SONGS) Unit 1 utilizing the tools developed by the Seismic Safety Margins Research Program (SSMRP). The main objectives of this project are to: identify the weak links of AFWS; compare the failure probabilities of SONGS 1 and Zion 1 AFWS: and compare the seismic responses due to different input spectra and design values

  3. Structure of Suasselkä Postglacial Fault in northern Finland obtained by analysis of ambient seismic noise

    Science.gov (United States)

    Afonin, Nikita; Kozlovskaya, Elena

    2016-04-01

    Understanding inner structure of seismogenic faults and their ability to reactivate is particularly important in investigating the continental intraplate seismicity regime. In our study we address this problem using analysis of ambient seismic noise recorded by the temporary DAFNE array in northern Fennoscandian Shield. The main purpose of the DAFNE/FINLAND passive seismic array experiment was to characterize the present-day seismicity of the Suasselkä post-glacial fault (SPGF) that was proposed as one potential target for the DAFNE (Drilling Active Faults in Northern Europe) project. The DAFNE/FINLAND array comprised the area of about 20 to 100 km and consisted of 8 short-period and 4 broad-band 3-component autonomous seismic stations installed in the close vicinity of the fault area. The array recorded continuous seismic data during September, 2011-May, 2013. Recordings of the array have being analyzed in order to identify and locate natural earthquakes from the fault area and to discriminate them from the blasts in the Kittilä Gold Mine. As a result, we found several dozens of natural seismic events originating from the fault area, which proves that the fault is still seismically active. In order to study the inner structure of the SPGF we use cross-correlation of ambient seismic noise recorded by the array. Analysis of azimuthal distribution of noise sources demonstrated that that during the time interval under consideration the distribution of noise sources is close to the uniform one. The continuous data were processed in several steps including single station data analysis, instrument response removal and time-domain stacking. The data were used to estimate empirical Green's functions between pairs of stations in the frequency band of 0.1-1 Hz and to calculate correspondent surface wave dispersion curves. After that S-wave velocity models were obtained as a result of dispersion curves inversion using Geopsy software. The results suggest that the area of

  4. Local magnitude, duration magnitude and seismic moment of Dahshour 1992 earthquakes

    Directory of Open Access Journals (Sweden)

    M. F. Abdelwahed

    2000-06-01

    Full Text Available Local magnitudes ML have been calculated for 56 earthquakes of the Dahshour 1992 sequence using simulated records of the KEG broadband station and the estimated calibration function of the Dahshour area. These were compared with their corresponding values of duration magnitudes obtained from the analog short period seismograms of the HLW station. The local magnitudes M L and the duration magnitudes M D for this region imply a linear relation as follows: M L = 1.2988 (± 0.04 M D – 0.9032 (± 0.14. Seismic moment has also been estimated for these events using simple measurements from the time domain records. These measurements based on the simulated Wood Anderson seismograms are used for the local magnitude (ML estimation. The derived relationship between seismic moment (M 0 and magnitude (M L is: log (M 0 = 0.954 (± 0.019 M L + 17.258 (± 0.075.

  5. Structure of the Suasselkä postglacial fault in northern Finland obtained by analysis of local events and ambient seismic noise

    Science.gov (United States)

    Afonin, Nikita; Kozlovskaya, Elena; Kukkonen, Ilmo; Dafne/Finland Working Group

    2017-04-01

    Understanding the inner structure of seismogenic faults and their ability to reactivate is particularly important in investigating the continental intraplate seismicity regime. In our study we address this problem using analysis of local seismic events and ambient seismic noise recorded by the temporary DAFNE array in the northern Fennoscandian Shield. The main purpose of the DAFNE/FINLAND passive seismic array experiment was to characterize the present-day seismicity of the Suasselkä postglacial fault (SPGF), which was proposed as one potential target for the DAFNE (Drilling Active Faults in Northern Europe) project. The DAFNE/FINLAND array comprised an area of about 20 to 100 km and consisted of eight short-period and four broadband three-component autonomous seismic stations installed in the close vicinity of the fault area. The array recorded continuous seismic data during September 2011-May 2013. Recordings of the array have being analysed in order to identify and locate natural earthquakes from the fault area and to discriminate them from the blasts in the Kittilä gold mine. As a result, we found a number of natural seismic events originating from the fault area, which proves that the fault is still seismically active. In order to study the inner structure of the SPGF we use cross-correlation of ambient seismic noise recorded by the array. Analysis of azimuthal distribution of noise sources demonstrated that during the time interval under consideration the distribution of noise sources is close to the uniform one. The continuous data were processed in several steps including single-station data analysis, instrument response removal and time-domain stacking. The data were used to estimate empirical Green's functions between pairs of stations in the frequency band of 0.1-1 Hz and to calculate corresponding surface wave dispersion curves. The S-wave velocity models were obtained as a result of dispersion curve inversion. The results suggest that the area of

  6. Ambient seismic noise interferometry in Hawai'i reveals long-range observability of volcanic tremor

    Science.gov (United States)

    Ballmer, Silke; Wolfe, Cecily; Okubo, Paul G.; Haney, Matt; Thurber, Clifford H.

    2013-01-01

    The use of seismic noise interferometry to retrieve Green's functions and the analysis of volcanic tremor are both useful in studying volcano dynamics. Whereas seismic noise interferometry allows long-range extraction of interpretable signals from a relatively weak noise wavefield, the characterization of volcanic tremor often requires a dense seismic array close to the source. We here show that standard processing of seismic noise interferometry yields volcanic tremor signals observable over large distances exceeding 50 km. Our study comprises 2.5 yr of data from the U.S. Geological Survey Hawaiian Volcano Observatory short period seismic network. Examining more than 700 station pairs, we find anomalous and temporally coherent signals that obscure the Green's functions. The time windows and frequency bands of these anomalous signals correspond well with the characteristics of previously studied volcanic tremor sources at Pu'u 'Ō'ō and Halema'uma'u craters. We use the derived noise cross-correlation functions to perform a grid-search for source location, confirming that these signals are surface waves originating from the known tremor sources. A grid-search with only distant stations verifies that useful tremor signals can indeed be recovered far from the source. Our results suggest that the specific data processing in seismic noise interferometry—typically used for Green's function retrieval—can aid in the study of both the wavefield and source location of volcanic tremor over large distances. In view of using the derived Green's functions to image heterogeneity and study temporal velocity changes at volcanic regions, however, our results illustrate how care should be taken when contamination by tremor may be present.

  7. Engineering of electrical systems of nuclear power stations for improved reliability

    International Nuclear Information System (INIS)

    Narasinga Rao, S.N.; Ramanathan, K.; Choudhary, N.N.

    1977-01-01

    Operational problems experienced in electrical systems/equipment of the Tarapur Atomic Power Station (TAPS) and the Rajasthan Atomic Power Station (RAPS) and their solutions are dealt in detail. This experience has led to new design concepts which are being introduced for improved reliability in design of the Madras Atomic Power Project (MAPP) and the Narora Atomic Power Project (NAPP). Saline pollution on switchyard equipments was the major problem of the TAPS due to its coastal location. Saline pollution resulted in flash over of insulators and failure of clamps. The problem was solved by suitable changes in insulators, conductors, transformers, switches and arranging portable live line washing of the switchyard equipment. In MAPP which is also located on coast, an indoor switchyard is built. NAPP is located in a seismic zone, therefore, all equipment is specified for appropriate seismic duty. Various other improvements are described. (M.G.B.)

  8. Monitoring the Dead Sea Region by Multi-Parameter Stations

    Science.gov (United States)

    Mohsen, A.; Weber, M. H.; Kottmeier, C.; Asch, G.

    2015-12-01

    The Dead Sea Region is an exceptional ecosystem whose seismic activity has influenced all facets of the development, from ground water availability to human evolution. Israelis, Palestinians and Jordanians living in the Dead Sea region are exposed to severe earthquake hazard. Repeatedly large earthquakes (e.g. 1927, magnitude 6.0; (Ambraseys, 2009)) shook the whole Dead Sea region proving that earthquake hazard knows no borders and damaging seismic events can strike anytime. Combined with the high vulnerability of cities in the region and with the enormous concentration of historical values this natural hazard results in an extreme earthquake risk. Thus, an integration of earthquake parameters at all scales (size and time) and their combination with data of infrastructure are needed with the specific aim of providing a state-of-the-art seismic hazard assessment for the Dead Sea region as well as a first quantitative estimate of vulnerability and risk. A strong motivation for our research is the lack of reliable multi-parameter ground-based geophysical information on earthquakes in the Dead Sea region. The proposed set up of a number of observatories with on-line data access will enable to derive the present-day seismicity and deformation pattern in the Dead Sea region. The first multi-parameter stations were installed in Jordan, Israel and Palestine for long-time monitoring. All partners will jointly use these locations. All stations will have an open data policy, with the Deutsches GeoForschungsZentrum (GFZ, Potsdam, Germany) providing the hard and software for real-time data transmission via satellite to Germany, where all partners can access the data via standard data protocols.

  9. SKS splitting observed at Romanian broad-band seismic network

    Science.gov (United States)

    Ivan, Marian; Popa, Mihaela; Ghica, Daniela

    2008-12-01

    Shear-wave splitting results are presented for the broad-band stations of the Romanian seismic network. For stations BUC1 and CRAR (located in Moesian Platform), IAS (in East-European Platform), TIRR and CVD (in Central Dobrudja-Black Sea microplate), TIM and DRGR (in Dacia-Tisza plate, including Apuseni Mts.), BURAR, BZS and GZR (in, or very close to the Carpathian Arc), the fast directions ( φ) are around 135°. The mean delay values ( δt) of the slow wave are slightly greater for the stations placed in platform areas ( δt ~ 1.5 s) than for the stations situated in the (proximity) of Carpathians ( δt ~ 1.2 s). For the MLR station located in the South-Western part of Vrancea area, at the Carpathian Bend, the fast direction is 48°, similar to VOIR station (located in Southern Carpathians, 70 km West of MLR). At VRI and PLOR, located in the North-Eastern part of Vrancea, the fast axis is oriented approximately on North-South direction, with a possible dependence of the splitting parameters with back azimuth. At least for some stations, the splitting results are not consistent with vertical coherent lithospheric anisotropy.

  10. Statistical characterization of Earth’s heterogeneities from seismic scattering

    Science.gov (United States)

    Zheng, Y.; Wu, R.

    2009-12-01

    The distortion of a teleseismic wavefront carries information about the heterogeneities through which the wave propagates and it is manifestited as logarithmic amplitude (logA) and phase fluctuations of the direct P wave recorded by a seismic network. By cross correlating the fluctuations (e.g., logA-logA or phase-phase), we obtain coherence functions, which depend on spatial lags between stations and incident angles between the incident waves. We have mathematically related the depth-dependent heterogeneity spectrum to the observable coherence functions using seismic scattering theory. We will show that our method has sharp depth resolution. Using the HiNet seismic network data in Japan, we have inverted power spectra for two depth ranges, ~0-120km and below ~120km depth. The coherence functions formed by different groups of stations or by different groups of earthquakes at different back azimuths are similar. This demonstrates that the method is statistically stable and the inhomogeneities are statistically stationary. In both depth intervals, the trend of the spectral amplitude decays from large scale to small scale in a power-law fashion with exceptions at ~50km for the logA data. Due to the spatial spacing of the seismometers, only information from length scale 15km to 200km is inverted. However our scattering method provides new information on small to intermediate scales that are comparable to scales of the recycled materials and thus is complimentary to the global seismic tomography which reveals mainly large-scale heterogeneities on the order of ~1000km. The small-scale heterogeneities revealed here are not likely of pure thermal origin. Therefore, the length scale and strength of heterogeneities as a function of depth may provide important constraints in mechanical mixing of various components in the mantle convection.

  11. The Future of Seismic Data Quality Assurance at the IRIS DMC

    Science.gov (United States)

    Templeton, M. E.; Sharer, G.; Ashmore, S.; Casey, R. E.; Ahern, T. K.

    2014-12-01

    The IRIS Data Management Center (DMC) hosts a large and ever-growing archive of data from seismic stations around the world. One of the challenges in maintaining this archive is the need for providing Quality Assurance (QA) on its contents so that the data can be most effectively used by the scientific community. In the past, IRIS has focussed its QA efforts on improving data quality for a targeted subset of seismic networks, most notably the Earthscope USArray Transportable Array and the Global Seismic Network (GSN). Now with the rollout of MUSTANG, the DMC's new automated data quality metrics system, we are embarking on an ambitious effort to bring QA to the entirety of the DMC seismic data archive. Analysts at the DMC are in the process of developing improved techniques to find data problems, document significant issues, and communicate our results. Our initial efforts are directed at creating a prototype of a scalable QA process using GSN data and MUSTANG metrics. We will show how MUSTANG metrics, both as single measurements and aggregates of multiple measurements, can be used to quickly flag potential problems and demonstrate how analysts can use visualization tools to track changes in data quality at stations and across networks. Communication between IRIS, network operators, and data users will be crucial to the success of any QA effort. To that end, we are also improving our web presence with the aim of increasing data quality awareness within the seismological community and providing a place where people can report issues they encounter with either data or metrics measurements.

  12. Three-dimensional seismic velocity structure and earthquake relocations at Katmai, Alaska

    Science.gov (United States)

    Murphy, Rachel; Thurber, Clifford; Prejean, Stephanie G.; Bennington, Ninfa

    2014-01-01

    We invert arrival time data from local earthquakes occurring between September 2004 and May 2009 to determine the three-dimensional (3D) upper crustal seismic structure in the Katmai volcanic region. Waveforms for the study come from the Alaska Volcano Observatory's permanent network of 20 seismic stations in the area (predominantly single-component, short period instruments) plus a densely spaced temporary array of 11 broadband, 3-component stations. The absolute and relative arrival times are used in a double-difference seismic tomography inversion to solve for 3D P- and S-wave velocity models for an area encompassing the main volcanic centers. The relocated hypocenters provide insight into the geometry of seismogenic structures in the area, revealing clustering of events into four distinct zones associated with Martin, Mageik, Trident-Novarupta, and Mount Katmai. The seismic activity extends from about sea level to 2 km depth (all depths referenced to mean sea level) beneath Martin, is concentrated near 2 km depth beneath Mageik, and lies mainly between 2 and 4 km depth below Katmai and Trident-Novarupta. Many new features are apparent within these earthquake clusters. In particular, linear features are visible within all clusters, some associated with swarm activity, including an observation of earthquake migration near Trident in 2008. The final velocity model reveals a possible zone of magma storage beneath Mageik, but there is no clear evidence for magma beneath the Katmai-Novarupta area where the 1912 eruptive activity occurred, suggesting that the storage zone for that eruption may have largely been evacuated, or remnant magma has solidified.

  13. Seismic qualification using digital signal processing/modal testing and finite element techniques

    International Nuclear Information System (INIS)

    Steedman, J.B.; Edelstein, A.

    1983-01-01

    A systematic procedure in which digital signal processing, modal testing and finite element techniques can be used to seismically qualify Class IE equipment for use in nuclear generating stations is presented. A new method was also developed in which measured transmissibility functions and Fourier transformation techniques were combined to compute instrument response spectra. As an illustrative example of the qualification method, the paper follows the qualification of a safety related Class IE Heating, Ventilating, and Air Conditioning (HVAC) Control Panel subjected to both seismic and hydrodynamic loading conditions

  14. Investigation on the real-time prediction of ground motions using seismic records observed in deep boreholes

    Science.gov (United States)

    Miyakoshi, H.; Tsuno, S.

    2013-12-01

    The present method of the EEW system installed in the railway field of Japan predicts seismic ground motions based on the estimated earthquake information about epicentral distances and magnitudes using initial P-waves observed on the surface. In the case of local earthquakes beneath the Tokyo Metropolitan Area, however, a method to directly predict seismic ground motions using P-waves observed in deep boreholes could issue EEWs more simply and surely. Besides, a method to predict seismic ground motions, using S-waves observed in deep boreholes and S-wave velocity structures beneath seismic stations, could show planar distributions of ground motions for train operation control areas in the aftermath of earthquakes. This information is available to decide areas in which the emergency inspection of railway structures should be performed. To develop those two methods, we investigated relationships between peak amplitudes on the surface and those in deep boreholes, using seismic records of KiK-net stations in the Kanto Basin. In this study, we used earthquake accelerograms observed in boreholes whose depths are deeper than the top face of Pre-Neogene basement and those on the surface at 12 seismic stations of KiK-net. We selected 243 local earthquakes whose epicenters are located around the Kanto Region. Those JMA magnitudes are in the range from 4.5 to 7.0. We picked the on-set of P-waves and S-waves using a vertical component and two horizontal components, respectively. Peak amplitudes of P-waves and S-waves were obtained using vertical components and vector sums of two horizontal components, respectively. We estimated parameters which represent site amplification factors beneath seismic stations, using peak amplitudes of S-waves observed in the deep borehole and those on the surface, to minimize the residuals between calculations by the theoretical equation and observations. Correlation coefficients between calculations and observations are high values in the range

  15. MOBB: a permanent ocean floor broadband seismic observatory in Monterey Bay, California

    Science.gov (United States)

    Uhrhammer, R.; Romanowicz, B.; Stakes, D.; Neuhauser, D.; McGill, P.; Ramirez, T.

    2003-04-01

    The Monterey ocean bottom broadband station (MOBB) was installed on the seafloor in Monterey Bay, 40 km offshore, and at a depth of 1000m from the sea surface, on April 9-11, 2002. Its success capitalizes on the experience gained in the 1997 International MOISE experiment, conducted under similar conditions. The deployment took place during 3 dives on consecutive days and made use of MBARI's Point Lobos ship and ROV Ventana. The station is currently recording data autonomously. Eventually, it will be linked to the planned (and recently funded) MARS (Monterey Accelerated Research System; \\url {http://www.mbari.org/mars/}) cable and provide real-time, continuous seismic data to be merged with the rest of the northern California real-time seismic system. The data are archived at the NCEDC for on-line availability, as part of the Berkeley Digital Seismic Network (BDSN). The ocean-bottom MOBB station currently comprises a three-component seismometer package, a current-meter, a DPG, and recording and battery packages. The seismic package contains a low-power (2.2W), three-component CMG-1T broadband seismometer system, built by Guralp, Inc., with a three-component 24-bit digitizer, a leveling system, and a precision clock. The seismometer package is mounted on a cylindrical titanium pressure vessel 54cm in height and 41 cm in diameter, custom built by the MBARI team and outfitted for underwater connection. Data recovery dives, during which the recording and battery package will be exchanged are planned every three months for the next 3 years. Three such dives have already taken place, on 06/27/02, 09/20/02 and on 01/07/03. Due to a software problem, data were lost during the time period 07/01/02 and 09/20/02. Many regional and teleseismic earthquakes have been well recorded and the mass position signals indicate that the instruments have progressively settled. Preliminary analysis of data retrieved during the 2002 summer and winter dives will be presented. In particular

  16. The seismic signatures of the 2009 Shiaolin landslide in Taiwan

    Directory of Open Access Journals (Sweden)

    Z. Feng

    2011-05-01

    Full Text Available The Shiaolin landslide occurred on 9 August 2009 after Typhoon Morakot struck Taiwan, claiming over 400 lives. The seismic signals produced by the landslide were recorded by broadband seismic stations in Taiwan. The time-frequency spectra for these signals were obtained by the Hilbert-Huang transform (HHT and were analyzed to obtain the seismic characteristics of the landslide. Empirical mode decomposition (EMD was applied to differentiate weak surface-wave signals from noise and to estimate the surface-wave velocities in the region. The surface-wave velocities were estimated using the fifth intrinsic mode function (IMF 5 obtained from the EMD. The spectra of the earthquake data were compared. The main frequency content of the seismic waves caused by the Shiaolin landslide were in the range of 0.5 to 1.5 Hz. This frequency range is smaller than the frequency ranges of other earthquakes. The spectral analysis of surface waves (SASW method is suggested for characterizing the shear-wave velocities of the strata in the region.

  17. Shallow velocity model in the area of Pozzo Pitarrone, Mt. Etna, from single station, array methods and borehole data

    Directory of Open Access Journals (Sweden)

    Luciano Zuccarello

    2016-09-01

    Full Text Available Seismic noise recorded by a temporary array installed around Pozzo Pitarrone, NE flank of Mt. Etna, have been analysed with several techniques. Single station HVSR method and SPAC array method have been applied to stationary seismic noise to investigate the local shallow structure. The inversion of dispersion curves produced a shear wave velocity model of the area reliable down to depth of about 130 m. A comparison of such model with the stratigraphic information available for the investigated area shows a good qualitative agreement. Taking advantage of a borehole station installed at 130 m depth, we could estimate also the P-wave velocity by comparing the borehole recordings of local earthquakes with the same event recorded at surface. Further insight on the P-wave velocity in the upper 130 m layer comes from the surface reflected wave observable in some cases at the borehole station. From this analysis we obtained an average P-wave velocity of about 1.2 km/s, compatible with the shear wave velocity found from the analysis of seismic noise.

  18. Anisotropic analysis for seismic sensitivity of groundwater monitoring wells

    Science.gov (United States)

    Pan, Y.; Hsu, K.

    2011-12-01

    Taiwan is located at the boundaries of Eurasian Plate and the Philippine Sea Plate. The movement of plate causes crustal uplift and lateral deformation to lead frequent earthquakes in the vicinity of Taiwan. The change of groundwater level trigged by earthquake has been observed and studied in Taiwan for many years. The change of groundwater may appear in oscillation and step changes. The former is caused by seismic waves. The latter is caused by the volumetric strain and reflects the strain status. Since the setting of groundwater monitoring well is easier and cheaper than the setting of strain gauge, the groundwater measurement may be used as a indication of stress. This research proposes the concept of seismic sensitivity of groundwater monitoring well and apply to DonHer station in Taiwan. Geostatistical method is used to analysis the anisotropy of seismic sensitivity. GIS is used to map the sensitive area of the existing groundwater monitoring well.

  19. High-resolution probing of inner core structure with seismic interferometry

    KAUST Repository

    Huang, Hsin-Hua

    2015-12-23

    © 2015. American Geophysical Union. All Rights Reserved. Increasing complexity of Earth\\'s inner core has been revealed in recent decades as the global distribution of seismic stations has improved. The uneven distribution of earthquakes, however, still causes a biased geographical sampling of the inner core. Recent developments in seismic interferometry, which allow for the retrieval of core-sensitive body waves propagating between two receivers, can significantly improve ray path coverage of the inner core. In this study, we apply such earthquake coda interferometry to 1846 USArray stations deployed across the U.S. from 2004 through 2013. Clear inner core phases PKIKP2 and PKIIKP2 are observed across the entire array. Spatial analysis of the differential travel time residuals between the two phases reveals significant short-wavelength variation and implies the existence of strong structural variability in the deep Earth. A linear N-S trending anomaly across the middle of the U.S. may reflect an asymmetric quasi-hemispherical structure deep within the inner core with boundaries of 99°W and 88°E.

  20. The 2012 Emilia seismic sequence (Northern Italy): Imaging the thrust fault system by accurate aftershock location

    Science.gov (United States)

    Govoni, Aladino; Marchetti, Alessandro; De Gori, Pasquale; Di Bona, Massimo; Lucente, Francesco Pio; Improta, Luigi; Chiarabba, Claudio; Nardi, Anna; Margheriti, Lucia; Agostinetti, Nicola Piana; Di Giovambattista, Rita; Latorre, Diana; Anselmi, Mario; Ciaccio, Maria Grazia; Moretti, Milena; Castellano, Corrado; Piccinini, Davide

    2014-05-01

    Starting from late May 2012, the Emilia region (Northern Italy) was severely shaken by an intense seismic sequence, originated from a ML 5.9 earthquake on May 20th, at a hypocentral depth of 6.3 km, with thrust-type focal mechanism. In the following days, the seismic rate remained high, counting 50 ML ≥ 2.0 earthquakes a day, on average. Seismicity spreads along a 30 km east-west elongated area, in the Po river alluvial plain, in the nearby of the cities Ferrara and Modena. Nine days after the first shock, another destructive thrust-type earthquake (ML 5.8) hit the area to the west, causing further damage and fatalities. Aftershocks following this second destructive event extended along the same east-westerly trend for further 20 km to the west, thus illuminating an area of about 50 km in length, on the whole. After the first shock struck, on May 20th, a dense network of temporary seismic stations, in addition to the permanent ones, was deployed in the meizoseismal area, leading to a sensible improvement of the earthquake monitoring capability there. A combined dataset, including three-component seismic waveforms recorded by both permanent and temporary stations, has been analyzed in order to obtain an appropriate 1-D velocity model for earthquake location in the study area. Here we describe the main seismological characteristics of this seismic sequence and, relying on refined earthquakes location, we make inferences on the geometry of the thrust system responsible for the two strongest shocks.

  1. Detecting Micro-seismicity and Long-duration Tremor-like Events from the Oklahoma Wavefield Experiment

    Science.gov (United States)

    Li, C.; Li, Z.; Peng, Z.; Zhang, C.; Nakata, N.

    2017-12-01

    Oklahoma has experienced abrupt increase of induced seismicity in the last decade. An important way to fully understand seismic activities in Oklahoma is to obtain more complete earthquake catalogs and detect different types of seismic events. The IRIS Community Wavefield Demonstration Experiment was deployed near Enid, Oklahoma in Summer of 2016. The dataset from this ultra-dense array provides an excellent opportunity for detecting microseismicity in that region with wavefield approaches. Here we examine continuous waveforms recorded by 3 seismic lines using local coherence for ultra-dense arrays (Li et al., 2017), which is a measure of cross-correlation of waveform at each station with its nearby stations. So far we have detected more than 5,000 events from 06/22/2016 to 07/20/2016, and majority of them are not listed on the regional catalog of Oklahoma or global catalogs, indicating that they are local events. We also identify 15-20 long-period long-duration events, some of them lasting for more than 500 s. Such events have been found at major plate-boundary faults (also known as deep tectonic tremor), as well as during hydraulic fracturing, slow-moving landslides and glaciers. Our next step is to locate these possible tremor-like events with their relative arrival times across the array and compare their occurrence times with solid-earth tides and injection histories to better understand their driving mechanisms.

  2. The Great Maule earthquake: seismicity prior to and after the main shock from amphibious seismic networks

    Science.gov (United States)

    Lieser, K.; Arroyo, I. G.; Grevemeyer, I.; Flueh, E. R.; Lange, D.; Tilmann, F. J.

    2013-12-01

    the Great Maule earthquake the Collaborative Research Center SFB 574 'Volatiles and Fluids in Subduction Zones' shot several wide-angle profiles and operated a network, also consisting of OBS and land stations for six months in 2008. Both projects provide a great opportunity to study the evolution of a subduction zone within the seismic cycle of a great earthquake. The most profound features are (i) a sharp reduction in intraslab seismic activity after the Maule earthquake and (ii) a sharp increase in seismic activity at the slab interface above 50 km depth, where large parts of the rupture zone were largely aseismic prior to the Maule earthquake. Further, the aftershock seismicity shows a broader depth distribution above 50 km depth.

  3. Broadband seismic deployments in East Antarctica: IPY contribution to monitoring the Earth’s interiors

    Directory of Open Access Journals (Sweden)

    Masaki Kanao

    2014-06-01

    Full Text Available “Deployment of broadband seismic stations on the Antarctica continent” is an ambitious project to improve the spatial resolution of seismic data across the Antarctic Plate and surrounding regions. Several international collaborative programs for the purpose of geomonitoring were conducted in Antarctica during the International Polar Year (IPY 2007-2008. The Antarctica’s GAmburtsev Province (AGAP; IPY #147, the GAmburtsev Mountain SEISmic experiment (GAMSEIS, a part of AGAP, and the Polar Earth Observing Network (POLENET; IPY #185 were major contributions in establishing a geophysical network in Antarctica. The AGAP/GAMSEIS project was an internationally coordinated deployment of more than 30 broadband seismographs over the crest of the Gambursev Mountains (Dome-A, Dome-C and Dome-F area. The investigations provide detailed information on crustal thickness and mantle structure; provide key constraints on the origin of the Gamburtsev Mountains; and more broadly on the structure and evolution of the East Antarctic craton and subglacial environment. From GAMSEIS and POLENET data obtained, local and regional seismic signals associated with ice movements, oceanic loading, and local meteorological variations were recorded together with a significant number of teleseismic events. In this chapter, in addition to the Earth’s interiors, we will demonstrate some of the remarkable seismic signals detected during IPY that illustrate the capabilities of broadband seismometers to study the sub-glacial environment, particularly at the margins of Antarctica. Additionally, the AGAP and POLENET stations have an important role in the Federation of Digital Seismographic Network (FDSN in southern high latitude.

  4. Quantifying the Benefits of Shallow Posthole Installation for the Future French Permanent Broadband Stations

    Science.gov (United States)

    Vergne, J.; Charade, O.; Bonaime, S.; Louis-Xavier, T.; Arnold, B.

    2015-12-01

    In the framework of the RESIF (réseau sismologique et géodésique français) infrastructure, more than one hundred new permanent broadband stations have to be deployed in metropolitan France within the forthcoming years. This requires a standardized installation method able to provide good noise level performance at a reasonable cost, especially for the 60 percent of stations that we expect to be settled in open environments. During the last two years we tested various types of sensor's hosting infrastructures with a strong focus on recently released posthole sensors that can be deployed at the bottom of shallow boreholes. Tests were performed at 3 different sites (two GEOSCOPE stations and a dedicated open-field prototype site) with geological conditions spanning from hard rocks to very soft soils. On each site, posthole sensors were deployed at different depths, from the surface to a maximum of 20m deep, and in different types of casing. Moreover, a reference sensor, either installed in a tunnel, a cellar or a seismic vault, has been operated continuously. We present a comprehensive comparison of the seismic noise level measured in the different hosting infrastructures and for several frequency bands corresponding to various sources of noise. At high and low frequencies, seismic noise level in some boreholes equals or outperforms the one obtained for the reference sensors. Between 0.005 and 0.05Hz, we observe a strong decrease of seismic noise level on the horizontal components in the deepest boreholes compared to near surface installations. This improvement can reach up to 30dB and is mostly due to a reduction in tilt noise induced by wind or local pressure variations. However, the absolute noise level that can be achieved clearly depends on the local geology. All these tests, together with estimated installation costs, point toward the deployment of sensors in shallow boreholes at the future French broadband stations located in open environments.

  5. Evaluation of Seismic Risk of Siberia Territory

    Science.gov (United States)

    Seleznev, V. S.; Soloviev, V. M.; Emanov, A. F.

    The outcomes of modern geophysical researches of the Geophysical Survey SB RAS, directed on study of geodynamic situation in large industrial and civil centers on the territory of Siberia with the purpose of an evaluation of seismic risk of territories and prediction of origin of extreme situations of natural and man-caused character, are pre- sented in the paper. First of all it concerns the testing and updating of a geoinformation system developed by Russian Emergency Ministry designed for calculations regarding the seismic hazard and response to distructive earthquakes. The GIS database contains the catalogues of earthquakes and faults, seismic zonation maps, vectorized city maps, information on industrial and housing fund, data on character of building and popula- tion in inhabited places etc. The geoinformation system allows to solve on a basis of probabilistic approaches the following problems: - estimating the earthquake impact, required forces, facilities and supplies for life-support of injured population; - deter- mining the consequences of failures on chemical and explosion-dangerous objects; - optimization problems on assurance technology of conduct of salvage operations. Using this computer program, the maps of earthquake risk have been constructed for several seismically dangerous regions of Siberia. These maps display the data on the probable amount of injured people and relative economic damage from an earthquake, which can occur in various sites of the territory according to the map of seismic zona- tion. The obtained maps have allowed determining places where the detailed seismo- logical observations should be arranged. Along with it on the territory of Siberia the wide-ranging investigations with use of new methods of evaluation of physical state of industrial and civil establishments (buildings and structures, hydroelectric power stations, bridges, dams, etc.), high-performance detailed electromagnetic researches of ground conditions of city

  6. Observations of Near-Field Rotational Motions from Oklahoma Seismicity using Applied Technology Associate Sensors

    Science.gov (United States)

    Ringler, A. T.; Anthony, R. E.; Holland, A. A.; Wilson, D. C.

    2017-12-01

    Characterizing rotational motions from moderate-sized earthquakes in the near-field has the potential to improve earthquake engineering and seismic gradiometry by better characterizing the rotational component of the seismic wavefield, but has remained challenging due to the limited development of portable, low-noise rotational sensors. Here, we test Applied Technology Associate (ATA) Proto-Seismic Magnetohydrodynamic (SMHD) three-component rotational rate sensors at Albuquerque Seismological Laboratory (ASL) for self-noise and sensitivity before deploying them at U.S. Geological Survey (USGS) temporary aftershock station OK38 in Waynoka, Oklahoma. The sensors have low self-noise levels below 2 Hz, making them ideal to record local rotations. From April 11, 2017 to June 6, 2017 we recorded the translational and rotational motions of over 155 earthquakes of ML≥2.0 within 2 degrees of the station. Using the recorded events we compare Peak Ground Velocity (PGV) with Peak Ground Rotation Rate (PG). For example, we measured a maximal PG of 0.00211 radians/s and 0.00186 radians/s for the horizontal components of the two rotational sensors during the Mwr=4.2 event on May 13, 2017 which was 0.5 km from that station. Similarly, our PG for the vertical rotational components were 0.00112 radians/s and 0.00085 radians/s. We also measured Peak Ground Rotations (PGω) as a function of seismic moment, as well as mean vertical Power Spectral Density (PSD) with mean horizontal PSD power levels. We compute apparent phase velocity directly from the rotational data, which may have may improve estimates of local site effects. Finally, by comparing various rotational and translational components we look at potential implications for estimating local event source parameters, which may help in identifying phenomena such as repeating earthquakes by using differences in the rotational components correlation.

  7. Real Time Seismic Loss Estimation in Italy

    Science.gov (United States)

    Goretti, A.; Sabetta, F.

    2009-04-01

    By more than 15 years the Seismic Risk Office is able to perform a real-time evaluation of the earthquake potential loss in any part of Italy. Once the epicentre and the magnitude of the earthquake are made available by the National Institute for Geophysiscs and Volca-nology, the model, based on the Italian Geographic Information Sys-tems, is able to evaluate the extent of the damaged area and the consequences on the built environment. In recent years the model has been significantly improved with new methodologies able to conditioning the uncertainties using observa-tions coming from the fields during the first days after the event. However it is reputed that the main challenges in loss analysis are related to the input data, more than to methodologies. Unlike the ur-ban scenario, where the missing data can be collected with enough accuracy, the country-wise analysis requires the use of existing data bases, often collected for other purposed than seismic scenario evaluation, and hence in some way lacking of completeness and homogeneity. Soil properties, building inventory and population dis-tribution are the main input data that are to be known in any site of the whole Italian territory. To this end the National Census on Popu-lation and Dwellings has provided information on the residential building types and the population that lives in that building types. The critical buildings, such as Hospital, Fire Brigade Stations, Schools, are not included in the inventory, since the national plan for seismic risk assessment of critical buildings is still under way. The choice of a proper soil motion parameter, its attenuation with distance and the building type fragility are important ingredients of the model as well. The presentation will focus on the above mentioned issues, highlight-ing the different data sets used and their accuracy, and comparing the model, input data and results when geographical areas with dif-ferent extent are considered: from the urban scenarios

  8. Constraining the dynamics of 2014-15 Bardarbunga-Holuhraun intrusion and eruption using seismic noise

    Science.gov (United States)

    Caudron, Corentin; Donaldson, Clare; White, Robert

    2016-04-01

    The 2010 Eyjafjallajokull volcanic eruption explosively emitted a large quantity of ash in the atmosphere and paralysed the European airspace for weeks. Several seismic scientific studies already contributed to the understanding of this complex eruption (e.g., Tarasewicz et al., 2012). Although an excellent network of seismometers recorded this eruption, some volcanological and seismological aspects are still poorly understood. In order to gain further constraints on the dynamics of this ground-breaking eruptions, we mine the seismic dataset using the seismic ambient noise technique between pairs of stations and the Seismic Amplitude Ratio Analysis (SARA). Our preliminary results reveal a strong contamination of the Cross Correlation Functions (CCF) by the volcanic tremor, particularly above 0.5 Hz even for station pairs located >50 km from the volcano. Although this volcanic tremor precludes the monitoring of the seismic velocities, it literally illuminated the medium. The two phases of the eruptions (i.e., effusive and explosive) are clearly distinguished in these functions due to their different locations. During the explosive phase, an intriguing shift of the main peaks of the cross correlation functions is evidenced (early May 2010). It is remarkably consistent with the downward migration proposed by Tarasewicz et al. (2012) and is interpreted as a migration of the volcanic tremor. SARA methodology, which is continuously imaging and tracking any significant seismicity at a 10-min time scale (Taisne et al., 2010), is applied in the 5-15 Hz frequency band in order to image to continuously migrating microseismicity. The analysis displays several shallow migrations (above 5 km of depth, in March 2010) preceding the effusive phase of the eruption. Interestingly, the results also evidence a fast and deep migration (> 5 km) starting a few hours before the beginning of the explosive phase (13 April 2010). These preliminary results may shed light on the triggering of

  9. Recent Seismicity in Texas and Research Design and Progress of the TexNet-CISR Collaboration

    Science.gov (United States)

    Hennings, P.; Savvaidis, A.; Rathje, E.; Olson, J. E.; DeShon, H. R.; Datta-Gupta, A.; Eichhubl, P.; Nicot, J. P.; Kahlor, L. A.

    2017-12-01

    The recent increase in the rate of seismicity in Texas has prompted the establishment of an interdisciplinary, interinstitutional collaboration led by the Texas Bureau of Economic Geology which includes the TexNet Seismic Monitoring and Research project as funded by The State of Texas (roughly 2/3rds of our funding) and the industry-funded Center for Integrated Seismicity Research (CISR) (1/3 of funding). TexNet is monitoring and cataloging seismicity across Texas using a new backbone seismic network, investigating site-specific earthquake sequences by deploying temporary seismic monitoring stations, and conducting reservoir modeling studies. CISR expands TexNet research into the interdisciplinary realm to more thoroughly study the factors that contribute to seismicity, characterize the associated hazard and risk, develop strategies for mitigation and management, and develop methods of effective communication for all stakeholders. The TexNet-CISR research portfolio has 6 themes: seismicity monitoring, seismology, geologic and hydrologic description, geomechanics and reservoir modeling, seismic hazard and risk assessment, and seismic risk social science. Twenty+ specific research projects span and connect these themes. We will provide a synopsis of research progress including recent seismicity trends in Texas; Fort Worth Basin integrated studies including geological modeling and fault characterization, fluid injection data syntheses, and reservoir and geomechanical modeling; regional ground shaking characterization and mapping, infrastructure vulnerability assessment; and social science topics of public perception and information seeking behavior.

  10. Patterns in Seismicity at Mt St Helens and Mt Unzen

    Science.gov (United States)

    Lamb, Oliver; De Angelis, Silvio; Lavallee, Yan

    2014-05-01

    Cyclic behaviour on a range of timescales is a well-documented feature of many dome-forming volcanoes. Previous work on Soufrière Hills volcano (Montserrat) and Volcán de Colima (Mexico) revealed broad-scale similarities in behaviour implying the potential to develop general physical models of sub-surface processes [1]. Using volcano-seismic data from Mt St Helens (USA) and Mt Unzen (Japan) this study explores parallels in long-term behaviour of seismicity at two dome-forming systems. Within the last twenty years both systems underwent extended dome-forming episodes accompanied by large Vulcanian explosions or dome collapses. This study uses a suite of quantitative and analytical techniques which can highlight differences or similarities in volcano seismic behaviour, and compare the behaviour to changes in activity during the eruptive episodes. Seismic events were automatically detected and characterized on a single short-period seismometer station located 1.5km from the 2004-2008 vent at Mt St Helens. A total of 714 826 individual events were identified from continuous recording of seismic data from 22 October 2004 to 28 February 2006 (average 60.2 events per hour) using a short-term/long-term average algorithm. An equivalent count will be produced from seismometer recordings over the later stages of the 1991-1995 eruption at MT Unzen. The event count time-series from Mt St Helens is then analysed using Multi-taper Method and the Short-Term Fourier Transform to explore temporal variations in activity. Preliminary analysis of seismicity from Mt St Helens suggests cyclic behaviour of subannual timescale, similar to that described at Volcán de Colima and Soufrière Hills volcano [1]. Frequency Index and waveform correlation tools will be implemented to analyse changes in the frequency content of the seismicity and to explore their relations to different phases of activity at the volcano. A single station approach is used to gain a fine-scale view of variations in

  11. Self-potential time series analysis in a seismic area of the Southern Apennines: preliminary results

    OpenAIRE

    Di Bello, G.; Lapenna, V.; Satriano, C.; Tramutoli, V.

    1994-01-01

    The self-potential time series recorded during the period May 1991 - August 1992 by an automatic station, located in a seismic area of Southern Apennines, is analyzed. We deal with the spectral and the statistical features of the electrotellurie precursors: they can play a major role in the approach to seismic prediction. The time-dynamics of the experimental time series is investigated, the cyclic components and the time trends are removed. In particular we consider the influence of external...

  12. Travel-time source-specific station correction improves location accuracy

    Science.gov (United States)

    Giuntini, Alessandra; Materni, Valerio; Chiappini, Stefano; Carluccio, Roberto; Console, Rodolfo; Chiappini, Massimo

    2013-04-01

    Accurate earthquake locations are crucial for investigating seismogenic processes, as well as for applications like verifying compliance to the Comprehensive Test Ban Treaty (CTBT). Earthquake location accuracy is related to the degree of knowledge about the 3-D structure of seismic wave velocity in the Earth. It is well known that modeling errors of calculated travel times may have the effect of shifting the computed epicenters far from the real locations by a distance even larger than the size of the statistical error ellipses, regardless of the accuracy in picking seismic phase arrivals. The consequences of large mislocations of seismic events in the context of the CTBT verification is particularly critical in order to trigger a possible On Site Inspection (OSI). In fact, the Treaty establishes that an OSI area cannot be larger than 1000 km2, and its larger linear dimension cannot be larger than 50 km. Moreover, depth accuracy is crucial for the application of the depth event screening criterion. In the present study, we develop a method of source-specific travel times corrections based on a set of well located events recorded by dense national seismic networks in seismically active regions. The applications concern seismic sequences recorded in Japan, Iran and Italy. We show that mislocations of the order of 10-20 km affecting the epicenters, as well as larger mislocations in hypocentral depths, calculated from a global seismic network and using the standard IASPEI91 travel times can be effectively removed by applying source-specific station corrections.

  13. Detecting Seismic Infrasound Signals on Balloon Platforms

    Science.gov (United States)

    Krishnamoorthy, S.; Komjathy, A.; Cutts, J. A.; Pauken, M.; Garcia, R.; Mimoun, D.; Jackson, J. M.; Kedar, S.; Smrekar, S. E.; Hall, J. L.

    2017-12-01

    The determination of the interior structure of a planet requires detailed seismic investigations - a process that entails the detection and characterization of seismic waves due to geological activities (e.g., earthquakes, volcanoes, etc.). For decades, this task has primarily been performed on Earth by an ever-expanding network of terrestrial seismic stations. However, on planets such as Venus, where the surface pressure and temperature can reach as high as 90 atmospheres and 450 degrees Celsius respectively, placing seismometers on the planet's surface poses a vexing technological challenge. However, the upper layers of the Venusian atmosphere are more benign and capable of hosting geophysical payloads for longer mission lifetimes. In order to achieve the aim of performing geophysical experiments from an atmospheric platform, JPL and its partners (ISAE-SUPAERO and California Institute of Technology) are in the process of developing technologies for detection of infrasonic waves generated by earthquakes from a balloon. The coupling of seismic energy into the atmosphere critically depends on the density differential between the surface of the planet and the atmosphere. Therefore, the successful demonstration of this technique on Earth would provide ample reason to expect success on Venus, where the atmospheric impedance is approximately 60 times that of Earth. In this presentation, we will share results from the first set of Earth-based balloon experiments performed in Pahrump, Nevada in June 2017. These tests involved the generation of artificial sources of known intensity using a seismic hammer and their detection using a complex network of sensors, including highly sensitive micro-barometers suspended from balloons, GPS receivers, geophones, microphones, and seismometers. This experiment was the first of its kind and was successful in detecting infrasonic waves from the earthquakes generated by the seismic hammer. We will present the first comprehensive analysis

  14. Seismic-fragility tests of new and accelerated-aged Class 1E battery cells

    International Nuclear Information System (INIS)

    Bonzon, L.L.; Janis, W.J.; Black, D.A.; Paulsen, G.A.

    1987-01-01

    The seismic-fragility response of naturally-aged nuclear station safety-related batteries is of interest for two reasons: (1) to determine actual failure modes and thresholds and (2) to determine the validity of using the electrical capacity of individual cells as an indicator of the potential survivability of a battery given a seismic event. Prior reports in this series discussed the seismic-fragility tests and results for three specific naturally-aged cell types: 12-year old NCX-2250, 10-year old LCU-13, and 10-year old FHC-19. This report focuses on the complementary approach, namely, the seismic-fragility response of accelerated-aged batteries. Of particular interest is the degree to which such approaches accurately reproduce the actual failure modes and thresholds. In these tests the significant aging effects observed, in terms of seismic survivability, were: embrittlement of cell cases, positive bus material and positive plate grids; and excessive sulphation of positive plate active material causing hardening and expansion of positive plates. The IEEE Standard 535 accelerated aging method successfully reproduced seismically significant aging effects in new cells but accelerated grid embrittlement an estimated five years beyond the conditional age of other components

  15. Efforts toward enhancing seismic safety at Kashiwazaki Kariwa nuclear power station

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, Kazuhiko

    2010-09-15

    Kashiwazaki-Kariwa Nuclear Power Station, 8212MW, was struck by M6.8 quakes in July 2007. TEPCO has steadily been conducting restoration and post-earthquake equipment integrity assessment, aiming to make it a disaster-resistant power station. 2 units among 7 resumed commercial operation by June 2010. This earthquake has provided a great deal of knowledge and information useful for nuclear safety improvement. It has also served as a valuable reference for the IAEA in developing earthquake-related guidelines. TEPCO would like to share the knowledge and information thereby contributing to improving the safety of nuclear power generation. We will introduce some of our activities.

  16. Seismic wave interaction with underground cavities

    Science.gov (United States)

    Schneider, Felix M.; Esterhazy, Sofi; Perugia, Ilaria; Bokelmann, Götz

    2016-04-01

    Realization of the future Comprehensive Nuclear Test Ban Treaty (CTBT) will require ensuring its compliance, making the CTBT a prime example of forensic seismology. Following indications of a nuclear explosion obtained on the basis of the (IMS) monitoring network further evidence needs to be sought at the location of the suspicious event. For such an On-Site Inspection (OSI) at a possible nuclear test site the treaty lists several techniques that can be carried out by the inspection team, including aftershock monitoring and the conduction of active seismic surveys. While those techniques are already well established, a third group of methods labeled as "resonance seismometry" is less well defined and needs further elaboration. A prime structural target that is expected to be present as a remnant of an underground nuclear explosion is a cavity at the location and depth the bomb was fired. Originally "resonance seismometry" referred to resonant seismic emission of the cavity within the medium that could be stimulated by an incident seismic wave of the right frequency and observed as peaks in the spectrum of seismic stations in the vicinity of the cavity. However, it is not yet clear which are the conditions for which resonant emissions of the cavity could be observed. In order to define distance-, frequency- and amplitude ranges at which resonant emissions could be observed we study the interaction of seismic waves with underground cavities. As a generic model for possible resonances we use a spherical acoustic cavity in an elastic full-space. To solve the forward problem for the full elastic wave field around acoustic spherical inclusions, we implemented an analytical solution (Korneev, 1993). This yields the possibility of generating scattering cross-sections, amplitude spectrums and synthetic seismograms for plane incident waves. Here, we focus on the questions whether or not we can expect resonant responses in the wave field scattered from the cavity. We show

  17. Study of seismic events in the Central Part of East European Platform

    Science.gov (United States)

    Gorbunova, Ella; Sanina, Irina; Ivanchenko, Galina; Nesterkina, Margarita; Konstantinovskaya, Natalya

    2015-04-01

    A measurement system for location seismic events in the Central Part of East European Platform is situated within the Mikhnevo Geophysical Observatory of the RAS Institute of Geospheres Dynamics and consists of 12 seismic stations. One vertical station is located in the center of the group in a shaft tunnel. The other stations are located on the periphery in three concentric circles and are almost equally spaced with regard to the terrain to ensure full azimuth coverage to the maximum extent possible. The unique array identifies events with a magnitude up to 3 at the distances until 1000 km within the Central Part of East European platform. Most of the events recorded by the Mikhnevo array at a distance of 60-500 km are man-made events represented by explosions in quarries during the development of mineral deposits. Long-term seismic records of explosions in quarries have been processed for the period from 2004 to 2014 to generate a database containing standard waveforms for each quarry. Some events of unknown origin appear in the records for this period; these do not correspond to the identified seismic forms for explosions in known quarries. Epicenter coordinates for these events do not match the coordinates of the known quarries. A cosmotectonic map of the Central Part of East European Platform was compiled during the studies using the LESSA software package (Lineament Extraction and Stripe Statistical Analysis) and data on the deep crustal structure, which made it possible to define the morphostructural plan and evaluate the geodynamic conditions in the area. The deep basement structure through the sedimentary cover is expressed in the surface texture of the area under study. The region's neotectonics is closely related to the history of deep structures, in particular, aulacogens extending in different directions, which may show in the contemporary morphostructural plan, mainly as inversion and partially inherited forms. Out of events of unknown nature

  18. Seismic evidence for multiple-stage exhumation of high/ultrahigh pressure metamorphic rocks in the eastern Dabie orogenic belt

    Science.gov (United States)

    Luo, Yinhe; Zhao, Kaifeng; Tang, Chi-Chia; Xu, Yixian

    2018-05-01

    The Dabie-Sulu orogenic belt in China contains one of the largest exposures of high and ultrahigh pressure (HP and UHP) metamorphic rocks in the world. The origin of HP/UHP metamorphic rocks and their exhumation to the surface in this belt have attracted great interest in the geologic community because the study of exhumation history of HP/UHP rocks helps to understand the process of continental-continental collision and the tectonic evolution of post-collision. However, the exhumation mechanism of the HP-UHP rocks to the surface is still contentious. In this study, by deploying 28 broadband seismic stations in the eastern Dabie orogenic belt and combining seismic data from 40 stations of the China National Seismic Network (CNSN), we image the high-resolution crustal isotropic shear velocity and radial anisotropy structure using ambient noise tomography. Our high-resolution 3D models provide new information about the exhumation mechanism of HP/UHP rocks and the origin of two dome structures.

  19. Regional passive seismic monitoring reveals dynamic glacier activity on Spitsbergen, Svalbard

    Directory of Open Access Journals (Sweden)

    Andreas Köhler

    2015-12-01

    Full Text Available Dynamic glacier activity is increasingly observed through passive seismic monitoring. We analysed near-regional-scale seismicity on the Arctic archipelago of Svalbard to identify seismic icequake signals and to study their spatial–temporal distribution within the 14-year period from 2000 until 2013. This is the first study that uses seismic data recorded on permanent broadband stations to detect and locate icequakes in different regions of Spitsbergen, the main island of the archipelago. A temporary local seismic network and direct observations of glacier calving and surging were used to identify icequake sources. We observed a high number of icequakes with clear spectral peaks between 1 and 8 Hz in different parts of Spitsbergen. Spatial clusters of icequakes could be associated with individual grounded tidewater glaciers and exhibited clear seasonal variability each year with more signals observed during the melt season. Locations at the termini of glaciers, and correlation with visual calving observations in situ at Kronebreen, a glacier in the Kongsfjorden region, show that these icequakes were caused dominantly by calving. Indirect evidence for glacier surging through increased calving seismicity was found in 2003 at Tunabreen, a glacier in central Spitsbergen. Another type of icequake was observed in the area of the Nathorstbreen glacier system. Seismic events occurred upstream of the glacier within a short time period between January and May 2009 during the initial phase of a major glacier surge. This study is the first step towards the generation and implementation of an operational seismic monitoring strategy for glacier dynamics in Svalbard.

  20. Seismicity Pattern and Fault Structure in the Central Himalaya Seismic Gap Using Precise Earthquake Hypocenters and their Source Parameters

    Science.gov (United States)

    Mendoza, M.; Ghosh, A.; Rai, S. S.

    2017-12-01

    The devastation brought on by the Mw 7.8 Gorkha earthquake in Nepal on 25 April 2015, reconditioned people to the high earthquake risk along the Himalayan arc. It is therefore imperative to learn from the Gorkha earthquake, and gain a better understanding of the state of stress in this fault regime, in order to identify areas that could produce the next devastating earthquake. Here, we focus on what is known as the "central Himalaya seismic gap". It is located in Uttarakhand, India, west of Nepal, where a large (> Mw 7.0) earthquake has not occurred for over the past 200 years [Rajendran, C.P., & Rajendran, K., 2005]. This 500 - 800 km long along-strike seismic gap has been poorly studied, mainly due to the lack of modern and dense instrumentation. It is especially concerning since it surrounds densely populated cities, such as New Delhi. In this study, we analyze a rich seismic dataset from a dense network consisting of 50 broadband stations, that operated between 2005 and 2012. We use the STA/LTA filter technique to detect earthquake phases, and the latest tools contributed to the Antelope software environment, to develop a large and robust earthquake catalog containing thousands of precise hypocentral locations, magnitudes, and focal mechanisms. By refining those locations in HypoDD [Waldhauser & Ellsworth, 2000] to form a tighter cluster of events using relative relocation, we can potentially illustrate fault structures in this region with high resolution. Additionally, using ZMAP [Weimer, S., 2001], we perform a variety of statistical analyses to understand the variability and nature of seismicity occurring in the region. Generating a large and consistent earthquake catalog not only brings to light the physical processes controlling the earthquake cycle in an Himalayan seismogenic zone, it also illustrates how stresses are building up along the décollment and the faults that stem from it. With this new catalog, we aim to reveal fault structure, study

  1. Towards Quantification of Glacier Dynamic Ice Loss through Passive Seismic Monitoring

    Science.gov (United States)

    Köhler, A.; Nuth, C.; Weidle, C.; Schweitzer, J.; Kohler, J.; Buscaino, G.

    2015-12-01

    Global glaciers and ice caps loose mass through calving, while existing models are currently not equipped to realistically predict dynamic ice loss. This is mainly because long-term continuous calving records, that would help to better understand fine scale processes and key climatic-dynamic feedbacks between calving, climate, terminus evolution and marine conditions, do not exist. Combined passive seismic/acoustic strategies are the only technique able to capture rapid calving events continuously, independent of daylight or meteorological conditions. We have produced such a continuous calving record for Kronebreen, a tidewater glacier in Svalbard, using data from permanent seismic stations between 2001 and 2014. However, currently no method has been established in cryo-seismology to quantify the calving ice loss directly from seismic data. Independent calibration data is required to derive 1) a realistic estimation of the dynamic ice loss unobserved due to seismic noise and 2) a robust scaling of seismic calving signals to ice volumes. Here, we analyze the seismic calving record at Kronebreen and independent calving data in a first attempt to quantify ice loss directly from seismic records. We make use of a) calving flux data with weekly to monthly resolution obtained from satellite remote sensing and GPS data between 2007 and 2013, and b) direct, visual calving observations in two weeks in 2009 and 2010. Furthermore, the magnitude-scaling property of seismic calving events is analyzed. We derive and discuss an empirical relation between seismic calving events and calving flux which for the first time allows to estimate a time series of calving volumes more than one decade back in time. Improving our model requires to incorporate more precise, high-resolution calibration data. A new field campaign will combine innovative, multi-disciplinary monitoring techniques to measure calving ice volumes and dynamic ice-ocean interactions simultaneously with terrestrial laser

  2. PG&E's Seismic Network Goes Digital With Strong Motion: Successes and Challenges

    Science.gov (United States)

    Stanton, M. A.; Cullen, J.; McLaren, M. K.

    2008-12-01

    Pacific Gas and Electric Company (PG&E) is in year 3 of a 5-year project to upgrade the Central Coast Seismic Network (CCSN) from analog to digital. Located along the south-central California coast, the CCSN began operation in 1987, with 20 analog stations; 15 vertical component and 5 dual gain 3-component S-13 sensors. The analog signals travel over FM radio telemetry links and voice channels via PG&E's microwave network to our facility in San Francisco (SF), where the A/D conversion is performed on a computer running Earthworm v7.1, which also transmits the data to the USGS in Menlo Park. At the conversion point the dynamic ranges of the vertical and dual-gain sensors are 40-50dB and 60-70dB, respectively. Dynamic range exceedance (data clipping) generally occurs for a M2.5 or greater event within about 40 km of a station. The motivations to upgrade the seismic network were the need for higher dynamic range and to retire obsolete analog transmission equipment. The upgraded digital stations consist of the existing velocity sensors, a 131A-02/3 accelerometer and a Reftek 130-01 Broadband Seismic Recorder for digital data recording and transmission to SF. Vertical only stations have one component of velocity and 3 components of acceleration. Dual gain sites have 3 components of velocity and 3 of acceleration. To date we have successfully upgraded 6 sites; 3 more will be installed by the end of 2008. Some of the advantages of going digital are 1) data is recorded at each site and in SF, 2) substantially increased dynamic range of the velocity sensors to 120dB, as observed by on scale, close-by recordings from a M3.9 San Simeon aftershock on 04/29/2008, 3) accelerometers for on scale recording of large earthquakes, and 4) ability to contribute our strong motion data to USGS ShakeMaps. A significant challenge has been consistent radio communications. To resolve this issue we are installing point-to-multipoint Motorola Canopy spread spectrum radios at the stations and

  3. High-resolution seismic reflection study, Vacherie Dome

    International Nuclear Information System (INIS)

    1984-06-01

    A high-resolution seismic reflection study, consisting of recording, processing, and interpreting four seismic reflection lines, was made at Vacherie Dome, Louisiana. The presumed shape of the dome, as pictured in the geologic area characterization report by Law Engineering Testing Company in 1982, was based largely on interpretation of gravity data, constrained by a few wells and exploration-type seismic profiles. The purpose of the study was to obtain refined profiles of the dome above -914 m (-3000 ft) elevation. Additional study had been recommended by Louisiana State University in 1967 and the Office of Nuclear Waste Isolation in 1981 because the interpreted size of Vacherie Dome was based on limited seismic and gravity data. Forty-eight traces of seismic data were recorded each time shots were made to generate energy. Twelve-fold, common-depth-point data were obtained using geophone stations spaced at 15-m (50-ft) intervals with shots at 30-m (100-ft) intervals. The time-sampling interval used was 1 ms. Processing intended to enhance resolution included iterative static corrections, deconvolution before stacking, and both time- and depth-migration. The locations of the steep dome sides were inferred primarily from terminations of strong reflections (migrated) from strata near the top of the upper and lower Cretaceous sections. This interpretation agrees closely with the presumed shape from the top of the dome to about -610 m (-2000 ft) elevation, but below this on three of the profiles, this interpretation indicates a steeper salt face than the presumed shape. The area reduction at -914 m (-3000 ft) elevation is estimated to be on the order of 20 percent. 10 references, 11 figures, 4 tables

  4. A new system for seismic yield estimation of underground explosions

    International Nuclear Information System (INIS)

    Murphy, J.R.

    1991-01-01

    Research conducted over the past decade has led to the development of a number of innovative procedures for estimating the yields of underground nuclear explosions based on systematic analyses of digital seismic data recorded from these tests. In addition, a wide variety of new data regarding the geophysical environments at Soviet test locations have now become available as a result of the Joint Verification Experiment (JVE) and associated data exchanges. The system described in this paper represents an attempt to integrate all these new capabilities and data into a comprehensive operational prototype which can be used to obtain optimum seismic estimates of explosion yield together with quantitative measures of the uncertainty in those estimates. The implementation of this system has involved a wide variety of technical tasks, including the development of a comprehensive seismic database and related database access software, formulation of a graphical test site information interface for accessing available information on explosion source conditions, design of an interactive seismic analyst station for use in processing the observed data to extract the required magnitude measures and the incorporation of formal statistical analysis modules for use in yield estimation and assessment

  5. A new multiparametric geophysical station to detect self-potential and seismometric signals at Tito site (Southern Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Balasco, M.; Lapenna, V.; Chianese, D.; Gallipoli, M. R. [Consiglio Nazionale delle Ricerche, Ist. di Metodologie Avanzate di Analisi Ambientale, Tito Scalo, PZ (Italy); Di Bello, G. [Potenza Universita' della Basilicata, Potenza (Italy). Dipt. di Ingegneria e Fisica dell' Ambiente

    2001-04-01

    In this work are presented the main features of a new multiparametric station able to jointly detect self-potential and seismometric signals in a seismic active area of Southern Italy. The new station has been designed and installed at the Tito Laboratories of National Research Council (Italy) that are located in the Southern Apennines, one of the most tectonically active areas of the whole Mediterranean. It combines advanced technologies for data acquisition with robust statistical techniques to pick out extreme events from self-potential recordings. The completely automatic station is equipped with electrical and seismometric sensors (16 channels, A/D 24 bit, sampling rate of 0.25 Hz, range dynamics of 133 dB). After a preliminary filtering procedure, mainly devoted to removing any influence of meteo-climatic conditions and/or cultural electrical noise, it was evaluated the performance of the new monitoring station investigating the possible correlation between anomalous patterns of the self-potential signals and local seismic activity. Objective criteria and robust statistical tools have been applied to identify extreme events in electrical measurements and to select the earthquakes that may be responsible for strain effects at the measuring point. The short period of the measuring activity does not allow anybody to give firm conclusions, however the first results encourage everybody to continue the monitoring activity by increasing the number of remote stations and improving the use of statistical packages for data processing. It was identified a well based monitoring strategy that in the near future could be useful to better understand the possible correlation between anomalous self-potential signals and local seismic activity.

  6. Feasibility study on earthquake early warning application to schools: the example of the ITIS 'E. Majorana', Somma Vesuviana, Naples (Italy)

    Science.gov (United States)

    Emolo, Antonio; Zollo, Aldo; Picozzi, Matteo; Martino, Claudio; Elia, Luca; Verderame, Gerardo; De Risi, Maria Teresa; Ricci, Paolo; Lombardi, Anna; Bindi, Dino; Parolai, Stefano; Boxberger, Tobias; Miranda, Nicola

    2014-05-01

    One of the main objective of the WP7 (Strategic Applications and Capacity Building) in the framework of the REAKT-Strategies and tools for Real Time Earthquake RisK ReducTion FP7 European project, is to evaluate the effectiveness of EEW and real-time risk assessment procedures in reducing seismic risk to various industrial partners and end-users. In the context of the REAKT project, the AMRA-RISSCLab group is engaged in a feasibility study on the application of earthquake early-warning procedures in two high schools located in the Irpinia region (South Italy), an area that in the 1980 was struck by a magnitude 6.9 earthquake. In this work we report on the activities carried out during the last 24 Months at the school ITIS 'E. Majorana', located in Somma Vesuviana, a village in the neighbourhood of Naples. In order to perform a continuous seismic monitoring of the site, which includes a rather complex structure building, 5 accelerometric stations have been installed in different part of the school. In particular, a 24-bit ADC (Sigma/Delta) Agecodagis-Kefren data-logger has been installed with a Guralp CMG-5TC accelerometer with a 0.25g full-scale in the school courtyard, while 4 SOSEWIN sensors have been also installed at different locations within the building. Commercial ADSL lines provide transmission of real-time data to the EEW centre. Data streams are now acquired in real-time in the PRESToPlus (regional and on-site, threshold-based early-warning) software platform [1]. The recent December 29, 2013 M 5.1 Monti del Matese Earthquake, gave us the unique opportunity to use real strong motion data to test the performance of threshold-based early warning method at the school. The on-site method [2] aims to define alert levels at the monitored site. In particular, at each station the characteristic P-waves period (τc) and the peak displacement (Pd) are measured on the initial P-wave signal. They are compared with threshold values, previously established through an

  7. Seismic-Proof Buildings in Developing Countries

    Directory of Open Access Journals (Sweden)

    Vittoria Laghi

    2017-08-01

    Full Text Available The use of “ductile seismic frames,” whose proper seismic behavior largely depends upon construction details and specific design rules, may do not always lead to effective seismic resistant structures, as dramatically denounced by the famous Chinese artist Ai Weiwei in his artwork Straight. The artwork (96 t of undulating metal bars that were salvaged from schools destroyed by the 2008 Sichuan, China earthquake, where over 5,000 students were killed is a clear denounce against the corruption yielding to shoddy construction methods. The issue of safe constructions against natural hazards appears even more important in developing countries where, in most cases, building structures are realized by non-expert workers, or even by simple “people from the street,” who does not have any technical knowledge on construction techniques and seismic engineering. In this paper, a brief history from the first frame structures to the more efficient wall-based structures is provided within Earthquake Engineering perspectives. The superior structural properties of box-type wall structures with respect to conventional frame structures envisage a change of paradigm from actual “ductility-based” Earthquake Engineering (centered on frame structures toward 100% safe buildings through a “strength-based” design exploiting the use of box-type wall-based structures.

  8. Earthquake source parameter and focal mechanism estimates for the Western Quebec Seismic Zone in eastern Canada

    Science.gov (United States)

    Rodriguez Padilla, A. M.; Onwuemeka, J.; Liu, Y.; Harrington, R. M.

    2017-12-01

    The Western Quebec Seismic Zone (WQSZ) is a 160-km-wide band of intraplate seismicity extending 500 km from the Adirondack Highlands (United States) to the Laurentian uplands (Canada). Historically, the WQSZ has experienced over fifteen earthquakes above magnitude 5, with the noteworthy MN5.2 Ladysmith event on May 17, 2013. Previous studies have associated seismicity in the area to the reactivation of Early Paleozoic normal faults within a failed Iapetan rift arm, or strength contrasts between mafic intrusions and felsic rocks due to the Mesozoic track of the Great Meteor hotspot. A good understanding of seismicity and its relation to pre-existing structures requires information about event source properties, such as static stress drop and fault plane orientation, which can be constrained via spectral analysis and focal mechanism solutions. Using data recorded by the CNSN and USArray Transportable Array, we first characterize b-value for 709 events between 2012 and 2016 in WQSZ, obtaining a value of 0.75. We then determine corner frequency and seismic moment values by fitting S-wave spectra on transverse components at all stations for 35 events MN 2.7+. We select event pairs with highly similar waveforms, proximal hypocenters, and magnitudes differing by 1-2 units. Our preliminary results using single-station spectra show corner frequencies of 15 to 40 Hz and stress drop values between 7 and 130 MPa, typical of intraplate seismicity. Last, we solve focal mechanism solutions of 35 events with impulsive P-wave arrivals at a minimum of 8 stations using the hybridMT moment tensor inversion algorithm. Our preliminary results suggest predominantly thrust faulting mechanisms, and at times oblique thrust faulting. The P-axis trend of the focal mechanism solutions suggests a principal stress orientation of NE-SW, which is consistent with that derived from focal mechanisms of earthquakes prior to 2013. We plan to fit the event pair spectral ratios to correct for attenuation

  9. Passive seismic experiment in the Olduvai Gorge and Laetoli region (Ngorongoro Conservation Area), Northern Tanzania.

    Science.gov (United States)

    Parisi, Laura; Lombardo, Luigi; Tang, Zheng; Mai, P. Martin

    2017-04-01

    The Olduvai Gorge and Laetoli basins, located within the Ngorogoro Conservation Area (NCA), are a cornerstone for understanding the evolution of early humans and are two paleo-antropological excavation sites of global importance. NCA is located at the boundary between the Tanzanian Craton and East African Rift (EAR), in the vicinity of Ngorongoro Crater and other major volcanic edifices. Thus, understanding the geology and tectonics of the NCA may shed light onto the question why early Hominins settled in this region. Environmental and geological conditions in the Olduvai and Laetoli region that promoted human settlement and development are still debated by geologists and paleo-anthropologists. Paleo-geographical reconstructions of the study area of the last 2 million years may take advantage of modern passive seismology. Therefore, we installed a dense seismic network covering a surface of approximately 30 x 40 km within the NCA to map the depth extent of known faults, and to identify seismically active faults that have no surface expression. Our ten seismic stations, equipped with Trillium Compact 120 s sensors, started to operate in June 2016 and will continue for a total of 2 years. At the end of the first year, other 5 stations will densify our network. Here we analyse data quality of the first four months of continuous recordings. Our network provides good quality 3-C waveforms in the frequency range of 0.7-50 Hz. Vertical component seismograms record frequencies reliably down to 8 mHz. Preliminary results of the seismicity obtained with standard location procedures show that NCA is characterised by frequent tectonic seismicity (not volcano-related) with Ml between 0.5 and 2.0. Seismic activity is more frequent in the South (Laetoli region) where major fault systems have not been recognised at the surface yet.

  10. Seismic isolation - efficient procedure for seismic response assessement

    International Nuclear Information System (INIS)

    Zamfir, M. A.; Androne, M.

    2016-01-01

    The aim of this analysis is to reduce the dynamic response of a structure. The seismic isolation solution must take into consideration the specific site ground motion. In this paper will be presented results obtained by applying the seismic isolation method. Based on the obtained results, important conclusions can be outlined: the seismic isolation device has the ability to reduce seismic acceleration of the seismic isolated structure to values that no longer present a danger to people and environment; the seismic isolation solution is limiting devices deformations to safety values for ensuring structural integrity and stability of the entire system; the effective seismic energy dissipation and with no side effects both for the seismic isolated building and for the devices used, and the return to the initial position before earthquake occurence are obtained with acceptable permanent displacement. (authors)

  11. Earth Observation from the International Space Station -Remote Sensing in Schools-

    Science.gov (United States)

    Schultz, Johannes; Rienow, Andreas; Graw, Valerie; Heinemann, Sascha; Selg, Fabian; Menz, Gunter

    2016-04-01

    Since spring 2014, the NASA High Definition Earth Viewing (HDEV) mission at the International Space Station (ISS) is online. HDEV consists of four cameras mounted at ESA's Columbus laboratory and is recording the earth 24/7. The educational project 'Columbus Eye - Live-Imagery from the ISS in Schools' has published a learning portal for earth observation from the ISS (www.columbuseye.uni-bonn.de). Besides a video live stream, the portal contains an archive providing spectacular footage, web-GIS and an observatory with interactive materials for school lessons. Columbus Eye is carried out by the University of Bonn and funded by the German Aerospace Center (DLR) Space Administration. Pupils should be motivated to work with the footage in order to learn about patterns and processes of the coupled human-environment system like volcano eruptions or deforestation. The material is developed on the experiences of the FIS (German abbreviation for "Remote Sensing in Schools") project and its learning portal (http://www.fis.uni-bonn.de). Based on the ISS videos three different teaching material types are developed. The simplest teaching type are provided by worksheets, which have a low degree of interactivity. Alongside a short didactical commentary for teachers is included. Additionally, videos, ancillary information, maps, and instructions for interactive school experiments are provided. The observatory contains the second type of the Columbus Eye teaching materials. It requires a high degree of self-organisation and responsibility of the pupils. Thus, the observatory provides the opportunity for pupils to freely construct their own hypotheses based on a spatial analysis tool similar to those provided by commercial software. The third type are comprehensive learning and teaching modules with a high degree of interactivity, including background information, interactive animations, quizzes and different analysis tools (e.g. change detection, classification, polygon or NDVI

  12. Pn-waves Travel-time Anomaly beneath Taiwan from Dense Seismic Array Observations and its Possible Tectonic Implications

    Science.gov (United States)

    Lin, Y. Y.; Huang, B. S.; Ma, K. F.; Hsieh, M. C.

    2015-12-01

    We investigated travel times of Pn waves, which are of great important for understanding the Moho structure in Taiwan region. Although several high quality tomographic studies had been carried out, observations of Pn waves are still the most comprehensive way to elucidate the Moho structure. Mapping the Moho structure of Taiwan had been a challenging due to the small spatial dimension of Taiwan island with two subduction systems. To decipher the tectonic structure and understanding of earthquake hazard, the island of Taiwan have been implemented by several high density seismic stations, including 71 short-period stations of Central Weather Bureau Seismic Network (CWBSN) and 42 broardband stations of Broadband Array in Taiwan for Seismology (BATS). High quality seismic records of these stations would be used to identify precise Pn-wave arrival times. After station-elevation correction, we measure the difference between the observed and theoretical Pn arrivals from the IASPI 91 model for each station. For correcting uncertainties of earthquake location and origin time, we estimate relative Pn anomaly, ΔtPn , between each station and a reference station. The pattern of ΔtPn reflects the depth anomaly of Moho beneath Taiwan. In general, Pn waves are commonly observed from shallow earthquake at epicentral distance larger than 120 km. We search the global catalog since 2005 and the criteria are M > 5.5, focal depth 150 km. The 12 medium earthquakes from north Luzon are considered for analysis. We choose a station, TWKB, in the most southern point of Taiwan as the reference station due to that all events are from the south. The results indicate obvious different patterns of ΔtPn from different back-azimuths. The ΔtPn pattern of the events in the first group from the south south-east indicates that the Pn arrivals delay suddenly when the Pn waves pass through the Central Range, suggesting the Moho becomes deep rapidly. However, we cannot recognize the same pattern when

  13. Seismic fragility testing of naturally-aged, safety-related, class 1E battery cells

    International Nuclear Information System (INIS)

    Bonzon, L.L.; Hente, D.B.; Kukreti, B.M.; Schendel, J.S.; Black, D.A.; Paulsen, G.D.; Tulk, J.D.; Janis, W.J.; Aucoin, B.D.

    1984-01-01

    The concern over seismic susceptibility of naturally-aged lead-acid batteries used for safety-related emergency power in nuclear power stations was brought about by battery problems that periodically had been reported in Licensee Event Reports (LERs). The Turkey Point Station had reported cracked and buckled plates in several cells in October 1974 (LER 75-5). The Fitzpatrick Station had reported cracked battery cell cases in October 1977 (LER 77-55) and again in September 1979 (LER 79-59). The Browns Ferry Station had reported a cracked cell leaking a small quantity of electrolyte in July 1981 (LER 81-42). The Indian Point Station had reported cracked and leaking cells in both February (LER 82-7) and April 1982 (LER 82-16); both of these LERs indicated the cracked cells were due to expansion (i.e., growth) of the positive plates

  14. Shear wave velocity versus quality factor: results from seismic noise recordings

    Science.gov (United States)

    Boxberger, Tobias; Pilz, Marco; Parolai, Stefano

    2017-08-01

    The assessment of the shear wave velocity (vs) and shear wave quality factor (Qs) for the shallow structure below a site is necessary to characterize its site response. In the past, methods based on the analysis of seismic noise have been shown to be very efficient for providing a sufficiently accurate estimation of the vs versus depth at reasonable costs for engineering seismology purposes. In addition, a slight modification of the same method has proved to be able to provide realistic Qs versus depth estimates. In this study, data sets of seismic noise recorded by microarrays of seismic stations in different geological environments of Europe and Central Asia are used to calculate both vs and Qs versus depth profiles. Analogous to the generally adopted approach in seismic hazard assessment for mapping the average shear wave velocity in the uppermost 30 m (vs30) as a proxy of the site response, this approach was also applied to the quality factor within the uppermost 30 m (Qs30). A slightly inverse correlation between both parameters is found based on a methodological consistent determination for different sites. Consequently, a combined assessment of vs and Qs by seismic noise analysis has the potential to provide a more comprehensive description of the geological structure below a site.

  15. Basin amplification of seismic waves in the city of Pahrump, Nevada.

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, Robert E.

    2005-07-01

    Sedimentary basins can increase the magnitude and extend the duration of seismic shaking. This potential for seismic amplification is investigated for Pahrump Valley, Nevada-California. The Pahrump Valley is located approximately 50 km northwest of Las Vegas and 75 km south of the Nevada Test Site. Gravity data suggest that the city of Pahrump sits atop a narrow, approximately 5 km deep sub-basin within the valley. The seismic amplification, or ''site effect'', was investigated using a combination of in situ velocity modeling and comparison of the waveforms and spectra of weak ground motion recorded in the city of Pahrump, Nevada, and those recorded in the nearby mountains. Resulting spectral ratios indicate seismic amplification factors of 3-6 over the deepest portion of Pahrump Valley. This amplification predominantly occurs at 2-2.5 Hz. Amplification over the deep sub-basin is lower than amplification at the sub-basin edge, location of the John Blume and Associates PAHA seismic station, which recorded many underground nuclear tests at the Nevada Test Site. A comprehensive analysis of basin amplification for the city of Pahrump should include 3-D basin modeling, due to the extreme basement topography of the Pahrump Valley.

  16. ASDF: An Adaptable Seismic Data Format with Full Provenance

    Science.gov (United States)

    Smith, J. A.; Krischer, L.; Tromp, J.; Lefebvre, M. P.

    2015-12-01

    In order for seismologists to maximize their knowledge of how the Earth works, they must extract the maximum amount of useful information from all recorded seismic data available for their research. This requires assimilating large sets of waveform data, keeping track of vast amounts of metadata, using validated standards for quality control, and automating the workflow in a careful and efficient manner. In addition, there is a growing gap between CPU/GPU speeds and disk access speeds that leads to an I/O bottleneck in seismic workflows. This is made even worse by existing seismic data formats that were not designed for performance and are limited to a few fixed headers for storing metadata.The Adaptable Seismic Data Format (ASDF) is a new data format for seismology that solves the problems with existing seismic data formats and integrates full provenance into the definition. ASDF is a self-describing format that features parallel I/O using the parallel HDF5 library. This makes it a great choice for use on HPC clusters. The format integrates the standards QuakeML for seismic sources and StationXML for receivers. ASDF is suitable for storing earthquake data sets, where all waveforms for a single earthquake are stored in a one file, ambient noise cross-correlations, and adjoint sources. The format comes with a user-friendly Python reader and writer that gives seismologists access to a full set of Python tools for seismology. There is also a faster C/Fortran library for integrating ASDF into performance-focused numerical wave solvers, such as SPECFEM3D_GLOBE. Finally, a GUI tool designed for visually exploring the format exists that provides a flexible interface for both research and educational applications. ASDF is a new seismic data format that offers seismologists high-performance parallel processing, organized and validated contents, and full provenance tracking for automated seismological workflows.

  17. Seismicity within the Irpinia Fault System As Monitored By Isnet (Irpinia Seismic Network) and Its Possible Relation with Fluid Storage

    Science.gov (United States)

    Festa, G.; Zollo, A.; Amoroso, O.; Ascione, A.; Colombelli, S.; Elia, L.; Emolo, A.; Martino, C.; Mazzoli, S.; Orefice, A.; Russo, G.

    2014-12-01

    ISNet (http://isnet.fisica.unina.it) is deployed in Southern Apennines along the active fault system responsible for the 1980, M 6.9 Irpinia earthquake. ISNet consists of 32 seismic stations equipped with both strong motion and velocimetric instruments (either broadband or short-period), with the aim of capture a broad set of seismic signals, from ambient noise to strong motion. Real time and near real time procedures run at ISNet with the goal of monitoring the seismicity, check possible space-time anomalies, detect seismic sequences and launch an earthquake early warning in the case of potential significant ground shaking in the area. To understand the role of fluids on the seismicity of the area, we investigated velocity and attenuation models. The former is built from accurate cross-correlation picking and S wave detection based onto polarization analysis. Joint inversion of both P and S arrival times is then based on a linearized multi-scale tomographic approach. Attenuation is instead obtained from inversion of displacement spectra, deconvolving for the source effect. High VP/VS and QS/QP >1 were found within a ~15 km wide rock volume where intense microseismicity is located. This indicates that concentration of seismicity is possibly controlled by high pore fluid pressure. This earthquake reservoir may come from a positive feedback between the seismic pumping that controls the fluid transmission through the fractured damage zone and the low permeability of cross fault barrier, increasing the fluid pore pressure within the fault bounded block. In this picture, sequences mostly occur at the base of this fluid rich layer. They show an anomalous pattern in the earthquake occurrence per magnitude classes; main events evolve with a complex source kinematics, as obtained from backprojection of apparent source time functions, indicating possible directivity effects. In this area sequences might be the key for understanding the transition between the deep

  18. The use of multiwavelets for uncertainty estimation in seismic surface wave dispersion.

    Energy Technology Data Exchange (ETDEWEB)

    Poppeliers, Christian [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-12-01

    This report describes a new single-station analysis method to estimate the dispersion and uncer- tainty of seismic surface waves using the multiwavelet transform. Typically, when estimating the dispersion of a surface wave using only a single seismic station, the seismogram is decomposed into a series of narrow-band realizations using a bank of narrow-band filters. By then enveloping and normalizing the filtered seismograms and identifying the maximum power as a function of frequency, the group velocity can be estimated if the source-receiver distance is known. However, using the filter bank method, there is no robust way to estimate uncertainty. In this report, I in- troduce a new method of estimating the group velocity that includes an estimate of uncertainty. The method is similar to the conventional filter bank method, but uses a class of functions, called Slepian wavelets, to compute a series of wavelet transforms of the data. Each wavelet transform is mathematically similar to a filter bank, however, the time-frequency tradeoff is optimized. By taking multiple wavelet transforms, I form a population of dispersion estimates from which stan- dard statistical methods can be used to estimate uncertainty. I demonstrate the utility of this new method by applying it to synthetic data as well as ambient-noise surface-wave cross-correlelograms recorded by the University of Nevada Seismic Network.

  19. Seismic snubber reduction on advanced gas-cooled reactor pipework

    International Nuclear Information System (INIS)

    Kennedy, P.A.; Harkin, N.J.

    1989-01-01

    Recent advances in pipework dynamic analysis procedures have enabled a more realistic approach to be taken to the design of pipework under earthquake loadings. In particular, it is proving possible to reduce the number of seismic snubbers employed to limit pipework displacements. This paper presents the background to, and outcome of, a snubber optimisation study performed for the main steam pipework system at Torness Nuclear Power Station. (author)

  20. Seismic and Infrasound Location

    Energy Technology Data Exchange (ETDEWEB)

    Arrowsmith, Stephen J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Begnaud, Michael L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-03-19

    This presentation includes slides on Signal Propagation Through the Earth/Atmosphere Varies at Different Scales; 3D Seismic Models: RSTT; Ray Coverage (Pn); Source-Specific Station Corrections (SSSCs); RSTT Conclusions; SALSA3D (SAndia LoS Alamos) Global 3D Earth Model for Travel Time; Comparison of IDC SSSCs to RSTT Predictions; SALSA3D; Validation and Model Comparison; DSS Lines in the Siberian Platform; DSS Line CRA-4 Comparison; Travel Time Δak135; Travel Time Prediction Uncertainty; SALSA3D Conclusions; Infrasound Data Processing: An example event; Infrasound Data Processing: An example event; Infrasound Location; How does BISL work?; BISL: Application to the 2013 DPRK Test; and BISL: Ongoing Research.

  1. Study on the application of ambient vibration tests to evaluate the effectiveness of seismic retrofitting

    Science.gov (United States)

    Liang, Li; Takaaki, Ohkubo; Guang-hui, Li

    2018-03-01

    In recent years, earthquakes have occurred frequently, and the seismic performance of existing school buildings has become particularly important. The main method for improving the seismic resistance of existing buildings is reinforcement. However, there are few effective methods to evaluate the effect of reinforcement. Ambient vibration measurement experiments were conducted before and after seismic retrofitting using wireless measurement system and the changes of vibration characteristics were compared. The changes of acceleration response spectrum, natural periods and vibration modes indicate that the wireless vibration measurement system can be effectively applied to evaluate the effect of seismic retrofitting. The method can evaluate the effect of seismic retrofitting qualitatively, it is difficult to evaluate the effect of seismic retrofitting quantitatively at this stage.

  2. Full Waveform Adjoint Seismic Tomography of the Antarctic Plate

    Science.gov (United States)

    Lloyd, A. J.; Wiens, D.; Zhu, H.; Tromp, J.; Nyblade, A.; Anandakrishnan, S.; Aster, R. C.; Huerta, A. D.; Winberry, J. P.; Wilson, T. J.; Dalziel, I. W. D.; Hansen, S. E.; Shore, P.

    2017-12-01

    Recent studies investigating the response and influence of the solid Earth on the evolution of the cryosphere demonstrate the need to account for 3D rheological structure to better predict ice sheet dynamics, stability, and future sea level impact, as well as to improve glacial isostatic adjustment models and more accurately measure ice mass loss. Critical rheological properties like mantle viscosity and lithospheric thickness may be estimated from shear wave velocity models that, for Antarctica, would ideally possess regional-scale resolution extending down to at least the base of the transition zone (i.e. 670 km depth). However, current global- and continental-scale seismic velocity models are unable to obtain both the resolution and spatial coverage necessary, do not take advantage of the full set of available Antarctic data, and, in most instance, employ traditional seismic imaging techniques that utilize limited seismogram information. We utilize 3-component earthquake waveforms from almost 300 Antarctic broadband seismic stations and 26 southern mid-latitude stations from 270 earthquakes (5.5 ≤ Mw ≤ 7.0) between 2001-2003 and 2007-2016 to conduct a full-waveform adjoint inversion for Antarctica and surrounding regions of the Antarctic plate. Necessary forward and adjoint wavefield simulations are performed utilizing SPECFEM3D_GLOBE with the aid of the Texas Advanced Computing Center. We utilize phase observations from seismogram segments containing P, S, Rayleigh, and Love waves, including reflections and overtones, which are autonomously identified using FLEXWIN. The FLEXWIN analysis is carried out over a short (15-50 s) and long (initially 50-150 s) period band that target body waves, or body and surface waves, respectively. As our model is iteratively refined, the short-period corner of the long period band is gradually reduced to 25 s as the model converges over 20 linearized inversion iterations. We will briefly present this new high

  3. Seismic testing

    International Nuclear Information System (INIS)

    Sollogoub, Pierre

    2001-01-01

    This lecture deals with: qualification methods for seismic testing; objectives of seismic testing; seismic testing standards including examples; main content of standard; testing means; and some important elements of seismic testing

  4. Quantifying uncertainties of seismic Bayesian inversion of Northern Great Plains

    Science.gov (United States)

    Gao, C.; Lekic, V.

    2017-12-01

    Elastic waves excited by earthquakes are the fundamental observations of the seismological studies. Seismologists measure information such as travel time, amplitude, and polarization to infer the properties of earthquake source, seismic wave propagation, and subsurface structure. Across numerous applications, seismic imaging has been able to take advantage of complimentary seismic observables to constrain profiles and lateral variations of Earth's elastic properties. Moreover, seismic imaging plays a unique role in multidisciplinary studies of geoscience by providing direct constraints on the unreachable interior of the Earth. Accurate quantification of uncertainties of inferences made from seismic observations is of paramount importance for interpreting seismic images and testing geological hypotheses. However, such quantification remains challenging and subjective due to the non-linearity and non-uniqueness of geophysical inverse problem. In this project, we apply a reverse jump Markov chain Monte Carlo (rjMcMC) algorithm for a transdimensional Bayesian inversion of continental lithosphere structure. Such inversion allows us to quantify the uncertainties of inversion results by inverting for an ensemble solution. It also yields an adaptive parameterization that enables simultaneous inversion of different elastic properties without imposing strong prior information on the relationship between them. We present retrieved profiles of shear velocity (Vs) and radial anisotropy in Northern Great Plains using measurements from USArray stations. We use both seismic surface wave dispersion and receiver function data due to their complementary constraints of lithosphere structure. Furthermore, we analyze the uncertainties of both individual and joint inversion of those two data types to quantify the benefit of doing joint inversion. As an application, we infer the variation of Moho depths and crustal layering across the northern Great Plains.

  5. The ANSS response to the Mw 5.8 Central Virginia Seismic Zone earthquake of August 23, 2011

    Science.gov (United States)

    McNamara, D. E.; Horton, S.; Benz, H.; Earle, P. S.; Withers, M. M.; Hayes, G. P.; Kim, W. Y.; Chapman, M. C.; Herrmann, R. B.; Petersen, M. D.; Williams, R. A.

    2011-12-01

    An Mw 5.8 earthquake (depth=6km) occurred on August 23, 2011 (17:51:04 UTC) near Mineral, Virginia, which was widely felt from Maine to Georgia along the eastern seaboard and west to Chicago and western Tennessee. The USGS tallied nearly 142,000 felt reports submitted to the Did You Feel It (DYFI) internet community intensity system, making it the most widely felt earthquake since the web-site began, and demonstrating that more people felt this earthquake than any other in U.S. history. Significant damage was reported in the epicentral area and as far away as Washington D.C. (135 km away); minor damage was reported in Baltimore (200 km). The reverse faulting earthquake occurred on a northeast-striking plane within a region of diffuse seismicity known as the Central Virginia Seismic Zone. Within the first week, the mainshock was followed by 17 aftershocks with magnitude greater than 2, including Mw 4.5, 4.2, and 3.8 events. In the days following the mainshock, 46 portable seismic stations were deployed by several organizations, making this among the best-recorded aftershock sequence in the eastern U.S. Within 24 hours of the mainshock, 8 portable stations were deployed in time to record the largest aftershock to date (M4.5). We will present the results of our post-earthquake response, including attenuation and site amplification observations using portable aftershock station data, details on the initial USGS NEIC post earthquake response products and an assessment of the seismotectonics of the Central Virginia Seismic Zone based on aftershock locations and source parameter modeling of the larger earthquakes.

  6. Infrasound and Seismic Recordings of Rocket Launches from Kennedy Space Center, 2016-2017

    Science.gov (United States)

    McNutt, S. R.; Thompson, G.; Brown, R. G.; Braunmiller, J.; Farrell, A. K.; Mehta, C.

    2017-12-01

    We installed a temporary 3-station seismic-infrasound network at Kennedy Space Center (KSC) in February 2016 to test sensor calibrations and train students in field deployment and data acquisitions techniques. Each station featured a single broadband 3-component seismometer and a 3-element infrasound array. In May 2016 the network was scaled back to a single station due to other projects competing for equipment. To date 8 rocket launches have been recorded by the infrasound array, as well as 2 static tests, 1 aborted launch and 1 rocket explosion (see next abstract). Of the rocket launches recorded 4 were SpaceX Falcon-9, 2 were ULA Atlas-5 and 2 were ULA Delta-IV. A question we attempt to answer is whether the rocket engine type and launch trajectory can be estimated with appropriate travel-time, amplitude-ratio and spectral techniques. For example, there is a clear Doppler shift in seismic and infrasound spectrograms from all launches, with lower frequencies occurring later in the recorded signal as the rocket accelerates away from the array. Another question of interest is whether there are relationships between jet noise frequency, thrust and/or nozzle velocity. Infrasound data may help answer these questions. We are now in the process of deploying a permanent seismic and infrasound array at the Astronaut Beach House. 10 more rocket launches are schedule before AGU. NASA is also conducting a series of 33 sonic booms over KSC beginning on Aug 21st. Launches and other events at KSC have provided rich sources of signals that are useful to characterize and gain insight into physical processes and wave generation from man-made sources.

  7. A study of the feasibility of monitoring sealed geological repositories using seismic sensors

    International Nuclear Information System (INIS)

    Garbin, H.D.; Herrington, P.B.; Kromer, R.P.

    1999-01-01

    Questions have arisen regarding the applicability of seismic sensors to detect mining (re-entry) with a tunnel boring machine (TBM). Unlike cut and blast techniques of mining which produce impulsive seismic signals, the TBM produces seismic signals which are of long duration. (There are well established techniques available for detecting and locating the sources of the impulsive signals). The Yucca Mountain repository offered an opportunity to perform field evaluations of the capabilities of seismic sensors because during much of 1996, mining there was progressing with the use of a TBM. During the mining of the repository's southern branch, an effort was designed to evaluate whether the TBM could be detected, identified and located using seismic sensors. Three data acquisition stations were established in the Yucca Mountain area to monitor the TBM activity. A ratio of short term average to long term average algorithm was developed for use in detection based on the characteristics shown in the time series. For location of the source of detected signals, FK analysis was used on the array data to estimate back azimuths. The back azimuth from the 3 component system was estimated from the horizontal components. Unique features in the timing of the seismic signal were used to identify the source as the TBM. (author)

  8. A study of the feasibility of monitoring sealed geological repositories using seismic sensors

    International Nuclear Information System (INIS)

    Garbin, H.D.; Herrington, P.B.; Kromer, R.P.

    1997-10-01

    Questions have arisen regarding the applicability of seismic sensors to detect mining (re-entry) with a tunnel boring machine (TBM). Unlike cut and blast techniques of mining which produce impulsive seismic signals, the TBM produces seismic signals which are of long duration. (There are well established techniques available for detecting and locating the sources of the impulsive signals.) The Yucca Mountain repository offered an opportunity to perform field evaluations of the capabilities of seismic sensors because during much of 1996, mining there was progressing with the use of a TBM. During the mining of the repository's southern branch, an effort was designed to evaluate whether the TBM could be detected, identified and located using seismic sensors. Three data acquisition stations were established in the Yucca Mountain area to monitor the TBM activity. A ratio of short term average to long term average algorithm was developed for use in detection based on the characteristics shown in the time series. For location of the source of detected signals, FK analysis was used on the array data to estimate back azimuths. The back azimuth from the 3 component system was estimated from the horizontal components. Unique features in the timing of the seismic signal were used to identify the source as the TBM

  9. seismic-py: Reading seismic data with Python

    Directory of Open Access Journals (Sweden)

    2008-08-01

    Full Text Available The field of seismic exploration of the Earth has changed
    dramatically over the last half a century. The Society of Exploration
    Geophysicists (SEG has worked to create standards to store the vast
    amounts of seismic data in a way that will be portable across computer
    architectures. However, it has been impossible to predict the needs of the
    immense range of seismic data acquisition systems. As a result, vendors have
    had to bend the rules to accommodate the needs of new instruments and
    experiment types. For low level access to seismic data, there is need for a
    standard open source library to allow access to a wide range of vendor data
    files that can handle all of the variations. A new seismic software package,
    seismic-py, provides an infrastructure for creating and managing drivers for
    each particular format. Drivers can be derived from one of the known formats
    and altered to handle any slight variations. Alternatively drivers can be
    developed from scratch for formats that are very different from any previously
    defined format. Python has been the key to making driver development easy
    and efficient to implement. The goal of seismic-py is to be the base system
    that will power a wide range of experimentation with seismic data and at the
    same time provide clear documentation for the historical record of seismic
    data formats.

  10. Earthquake Early Warning: New Strategies for Seismic Hardware

    Science.gov (United States)

    Allardice, S.; Hill, P.

    2017-12-01

    Implementing Earthquake Early Warning System (EEWS) triggering algorithms into seismic networks has been a hot topic of discussion for some years now. With digitizer technology now available, such as the Güralp Minimus, with on average 40-60ms delay time (latency) from earthquake origin to issuing an alert the next step is to provide network operators with a simple interface for on board parameter calculations from a seismic station. A voting mechanism is implemented on board which mitigates the risk of false positives being communicated. Each Minimus can be configured to with a `score' from various sources i.e. Z channel on seismometer, N/S E/W channels on accelerometer and MEMS inside Minimus. If the score exceeds the set threshold then an alert is sent to the `Master Minimus'. The Master Minimus within the network will also be configured as to when the alert should be issued i.e. at least 3 stations must have triggered. Industry standard algorithms focus around the calculation of Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), Peak Ground Displacement (PGD) and C. Calculating these single station parameters on-board in order to stream only the results could help network operators with possible issues, such as restricted bandwidth. Developments on the Minimus allow these parameters to be calculated and distributed through Common Alert Protocol (CAP). CAP is the XML based data format used for exchanging and describing public warnings and emergencies. Whenever the trigger conditions are met the Minimus can send a signed UDP packet to the configured CAP receiver which can then send the alert via SMS, e-mail or CAP forwarding. Increasing network redundancy is also a consideration when developing these features, therefore the forwarding CAP message can be sent to multiple destinations. This allows for a hierarchical approach by which the single station (or network) parameters can be streamed to another Minimus, or data centre, or both, so that there is no

  11. Unified Geophysical Cloud Platform (UGCP) for Seismic Monitoring and other Geophysical Applications.

    Science.gov (United States)

    Synytsky, R.; Starovoit, Y. O.; Henadiy, S.; Lobzakov, V.; Kolesnikov, L.

    2016-12-01

    We present Unified Geophysical Cloud Platform (UGCP) or UniGeoCloud as an innovative approach for geophysical data processing in the Cloud environment with the ability to run any type of data processing software in isolated environment within the single Cloud platform. We've developed a simple and quick method of several open-source widely known software seismic packages (SeisComp3, Earthworm, Geotool, MSNoise) installation which does not require knowledge of system administration, configuration, OS compatibility issues etc. and other often annoying details preventing time wasting for system configuration work. Installation process is simplified as "mouse click" on selected software package from the Cloud market place. The main objective of the developed capability was the software tools conception with which users are able to design and install quickly their own highly reliable and highly available virtual IT-infrastructure for the organization of seismic (and in future other geophysical) data processing for either research or monitoring purposes. These tools provide access to any seismic station data available in open IP configuration from the different networks affiliated with different Institutions and Organizations. It allows also setting up your own network as you desire by selecting either regionally deployed stations or the worldwide global network based on stations selection form the global map. The processing software and products and research results could be easily monitored from everywhere using variety of user's devices form desk top computers to IT gadgets. Currents efforts of the development team are directed to achieve Scalability, Reliability and Sustainability (SRS) of proposed solutions allowing any user to run their applications with the confidence of no data loss and no failure of the monitoring or research software components. The system is suitable for quick rollout of NDC-in-Box software package developed for State Signatories and aimed for

  12. Definition of Exclusion Zones Using Seismic Data

    Science.gov (United States)

    Bartal, Y.; Villagran, M.; Ben Horin, Y.; Leonard, G.; Joswig, M.

    - In verifying compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), there is a motivation to be effective, efficient and economical and to prevent abuse of the right to conduct an On-site Inspection (OSI) in the territory of a challenged State Party. In particular, it is in the interest of a State Party to avoid irrelevant search in specific areas. In this study we propose several techniques to determine `exclusion zones', which are defined as areas where an event could not have possibly occurred. All techniques are based on simple ideas of arrival time differences between seismic stations and thus are less prone to modeling errors compared to standard event location methods. The techniques proposed are: angular sector exclusion based on a tripartite micro array, half-space exclusion based on a station pair, and closed area exclusion based on circumferential networks.

  13. Qualifying commercial grade instruments for use in nuclear power generating stations

    International Nuclear Information System (INIS)

    Lamothe, R.J.; Scally, C.R.

    1983-01-01

    Nuclear environmental qualification of instrumentation has been successfully accomplished by many commercial grade equipment manufacturers. This paper was prepared as a guide to those manufacturers who want some insight into a qualification program. The areas addressed are the regulations and documents, the qualification program, and a case history of a chart recorder qualifications. The principal standards relating to a nuclear qualification program are IEEE Std. 323-1974 IEEE Standard for Qualifying Class 1E Equipment for Nuclear Power Generating Stations, IEEE Std. 344-1975 IEEE Recommended Practices for Seismic Qualification of Class 1E Equipment for Nuclear Power Generating Stations and 10CFR50.49. Previously NUREG 0588 Interim Staff Position on Environmental Qualification of Safety-Related Equipment. These define the intent and purpose of the qualification. The qualification program itself consists of several distinct parts which require explanation, including the determination of qualified life, choice of test samples, selection of appropriate acceptance criteria, aging program, radiation testing, seismic testing, abnormal environment tests and others. The case history illustrates the qualification program and the thought processes involved

  14. Characteristics of seismic waves from Soviet peaceful nuclear explosions in salt

    Energy Technology Data Exchange (ETDEWEB)

    Adushkin, V.V.; Kaazik, P.B.; Kostyuchenko, V.N.; Kuznetsov, O.P.; Nedoshivin, N.I.; Rubinshtein, K.D.; Sultanov, D.D. [Academy of Sciences, Moscow (Russian Federation). Inst. for Dynamics of the Geospheres

    1995-04-01

    The report is carried out by the Institute for Dynamics of the Geospheres, Russian Academy of Sciences under contract NB280344 with Lawrence Livermore National Laboratory, University of California. The work includes investigation of seismic waves generation and propagation from Soviet peaceful underground nuclear explosions in salt based on the data from temporary and permanent seismic stations. The explosions were conducted at the sites Azgir and Vega within the territory of the Caspian depression of the Russian platform. The data used were obtained in the following conditions of conduction: epicentral distance range from 0 to 60 degrees, yields from 1 to 65 kt and depths of burial from 160 to 1500 m.

  15. Full Seismic Waveform Tomography of the Japan region using Adjoint Methods

    Science.gov (United States)

    Steptoe, Hamish; Fichtner, Andreas; Rickers, Florian; Trampert, Jeannot

    2013-04-01

    We present a full-waveform tomographic model of the Japan region based on spectral-element wave propagation, adjoint techniques and seismic data from dense station networks. This model is intended to further our understanding of both the complex regional tectonics and the finite rupture processes of large earthquakes. The shallow Earth structure of the Japan region has been the subject of considerable tomographic investigation. The islands of Japan exist in an area of significant plate complexity: subduction related to the Pacific and Philippine Sea plates is responsible for the majority of seismicity and volcanism of Japan, whilst smaller micro-plates in the region, including the Okhotsk, and Okinawa and Amur, part of the larger North America and Eurasia plates respectively, contribute significant local intricacy. In response to the need to monitor and understand the motion of these plates and their associated faults, numerous seismograph networks have been established, including the 768 station high-sensitivity Hi-net network, 84 station broadband F-net and the strong-motion seismograph networks K-net and KiK-net in Japan. We also include the 55 station BATS network of Taiwan. We use this exceptional coverage to construct a high-resolution model of the Japan region from the full-waveform inversion of over 15,000 individual component seismograms from 53 events that occurred between 1997 and 2012. We model these data using spectral-element simulations of seismic wave propagation at a regional scale over an area from 120°-150°E and 20°-50°N to a depth of around 500 km. We quantify differences between observed and synthetic waveforms using time-frequency misfits allowing us to separate both phase and amplitude measurements whilst exploiting the complete waveform at periods of 15-60 seconds. Fréchet kernels for these misfits are calculated via the adjoint method and subsequently used in an iterative non-linear conjugate-gradient optimization. Finally, we employ

  16. A dense microseismic monitoring network in Korea for uncovering relationship between seismic activity and neotectonic features

    Science.gov (United States)

    Kang, T.; Lee, J. M.; Kim, W.; Jo, B. G.; Chung, T.; Choi, S.

    2012-12-01

    A few tens of surface traces indicating movements in Quaternary were found in the southeastern part of the Korean Peninsula. Following both the geological and engineering definitions, those features are classified into "active", in geology, or "capable", in engineering, faults. On the other hand, the present-day seismicity of the region over a couple of thousand years is indistinguishable on the whole with the rest of the Korean Peninsula. It is therefore of great interest whether the present seismic activity is related to the neotectonic features or not. Either of conclusions is not intuitive in terms of the present state of seismic monitoring network in the region. Thus much interest in monitoring seismicity to provide an improved observation resolution and to lower the event-detection threshold has increased with many observations of the Quaternary faults. We installed a remote, wireless seismograph network which is composed of 20 stations with an average spacing of 10 km. Each station is equipped with a three-component Trillium Compact seismometer and Taurus digitizer. Instrumentation and analysis advancements are now offering better tools for this monitoring. This network is scheduled to be in operation over about one and a half year. In spite of the relatively short observation period, we expect that the high density of the network enables us to monitor seismic events with much lower magnitude threshold compared to the preexisting seismic network in the region. Following the Gutenberg-Richter relationship, the number of events with low magnitude is logarithmically larger than that with high magnitude. Following this rule, we can expect that many of microseismic events may reveal behavior of their causative faults, if any. We report the results of observation which has been performed over a year up to now.

  17. The Seismic Broad Band Western Mediterranean (wm) Network and the Obs Fomar Pool: Current state and Obs activities.

    Science.gov (United States)

    Pazos, Antonio; Davila, Jose Martin; Buforn, Elisa; Bezzeghoud, Mourad; Harnafi, Mimoun; Mattesini, Mauricio; Caldeira, Bento; Hanka, Winfried; El Moudnib, Lahcen; Strollo, Angelo; Roca, Antoni; Lopez de Mesa, Mireya; Dahm, Torsten; Cabieces, Roberto

    2016-04-01

    The Western Mediterranean (WM) seismic network started in 1996 as an initiative of the Royal Spanish Navy Observatory (ROA) and the Universidad Complutense de Madrid (UCM), with the collaboration of the GeoForschungsZentrum (GFZ) of Potsdam. A first broad band seismic station (SFUC) was installed close to Cádiz (South Spain). Since then, additional stations have been installed in the Ibero-Moghrebian region. In 2005, the "WM" code was assigned by the FDSN and new partners were jointed: Evora University (UEVO, Portugal), the Scientifique Institute of Rabat (ISRABAT, Morocco), and GFZ. Now days, the WM network is composed by 15 BB stations, all of them with Streckaisen STS-2 or STS-2.5 sensors, Quanterra or Earthdata digitizers and SeiscomP. Most them have co-installed a permanent geodetic GPS stations, and some them also have an accelerometer. There are 10 stations deployed in Spanish territory (5 in the Iberian peninsula, 1 in Balearic islands and 4 in North Africa Spanish places) with VSAT or Internet communications, 2 in Portugal (one of them without real time), and 3 in Morocco (2 VSAT and 1 ADSL). Additionally, 2 more stations (one in South Spain and one in Morocco) will be installed along this year. Additionally ROA has deployed a permanent real time VBB (CMG-3T: 360s) station at the Alboran Island. Due to the fact that part of the seismic activity is located at marine areas, and also because of the poor geographic azimuthal coverage at some zones provided by the land stations (specially in the SW of the San Vicente Cape area), ROA and UCM have acquired six broad band "LOBSTERN" OBS, manufactured by KUM (Kiel, Germany), conforming the OBS FOMAR pool. Three of them with CMG-40T sensor and the other with Trillium 120. These OBS were deployed along the Gibraltar strait since January to November 2014 to study the microseismicity in the Gibraltar strait area. In September 2015 FOMAR network has been deployed in SW of the San Vicente Cape for 8 months as a part of

  18. Application of Rudoe’s Formula in Long Seismic Surface Wave Paths Determination

    Directory of Open Access Journals (Sweden)

    Jorge L. de Souza

    2005-12-01

    Full Text Available An algorithm to compute accurate distances over grid cells crossed by seismic surface wave paths by Rudoe’s formula is proposed. The intersection coordinates between paths and the geodetic grid are also computed, which data are exhibited in an azimuthal equidistant projection to check the results. GRS-80 is the adopted ellipsoidal Earth model. The algorithm computes the intermediate intersections, from both forward and reciprocal normal sections given by Rudoe’s method, which separation may be greater than the cell size. It was tested on a data set including 3,269 source-station paths, which seismic events were recorded at 23 IRIS stations. The epicentral distances range from 1,634 km to 16,400 km, which the grid spreads over 149°E x 21°W, and 50°N x 90°S. The results show that the estimated intersections accuracy depends on the path azimuth and latitude, which influence may be significative for very long distances as in teleseismic applications, which argues for the algorithm application.

  19. Linearized inversion frameworks toward high-resolution seismic imaging

    KAUST Repository

    Aldawood, Ali

    2016-09-01

    Seismic exploration utilizes controlled sources, which emit seismic waves that propagate through the earth subsurface and get reflected off subsurface interfaces and scatterers. The reflected and scattered waves are recorded by recording stations installed along the earth surface or down boreholes. Seismic imaging is a powerful tool to map these reflected and scattered energy back to their subsurface scattering or reflection points. Seismic imaging is conventionally based on the single-scattering assumption, where only energy that bounces once off a subsurface scatterer and recorded by a receiver is projected back to its subsurface position. The internally multiply scattered seismic energy is considered as unwanted noise and is usually suppressed or removed from the recorded data. Conventional seismic imaging techniques yield subsurface images that suffer from low spatial resolution, migration artifacts, and acquisition fingerprint due to the limited acquisition aperture, number of sources and receivers, and bandwidth of the source wavelet. Hydrocarbon traps are becoming more challenging and considerable reserves are trapped in stratigraphic and pinch-out traps, which require highly resolved seismic images to delineate them. This thesis focuses on developing and implementing new advanced cost-effective seismic imaging techniques aiming at enhancing the resolution of the migrated images by exploiting the sparseness of the subsurface reflectivity distribution and utilizing the multiples that are usually neglected when imaging seismic data. I first formulate the seismic imaging problem as a Basis pursuit denoise problem, which I solve using an L1-minimization algorithm to obtain the sparsest migrated image corresponding to the recorded data. Imaging multiples may illuminate subsurface zones, which are not easily illuminated by conventional seismic imaging using primary reflections only. I then develop an L2-norm (i.e. least-squares) inversion technique to image

  20. The influence of construction measurement and structure storey on seismic performance of masonry structure

    Science.gov (United States)

    Sun, Baitao; Zhao, Hexian; Yan, Peilei

    2017-08-01

    The damage of masonry structures in earthquakes is generally more severe than other structures. Through the analysis of two typical earthquake damage buildings in the Wenchuan earthquake in Xuankou middle school, we found that the number of storeys and the construction measures had great influence on the seismic performance of masonry structures. This paper takes a teachers’ dormitory in Xuankou middle school as an example, selected the structure arrangement and storey number as two independent variables to design working conditions. Finally we researched on the seismic performance difference of masonry structure under two variables by finite element analysis method.

  1. Automatic Classification of Station Quality by Image Based Pattern Recognition of Ppsd Plots

    Science.gov (United States)

    Weber, B.; Herrnkind, S.

    2017-12-01

    The number of seismic stations is growing and it became common practice to share station waveform data in real-time with the main data centers as IRIS, GEOFON, ORFEUS and RESIF. This made analyzing station performance of increasing importance for automatic real-time processing and station selection. The value of a station depends on different factors as quality and quantity of the data, location of the site and general station density in the surrounding area and finally the type of application it can be used for. The approach described by McNamara and Boaz (2006) became standard in the last decade. It incorporates a probability density function (PDF) to display the distribution of seismic power spectral density (PSD). The low noise model (LNM) and high noise model (HNM) introduced by Peterson (1993) are also displayed in the PPSD plots introduced by McNamara and Boaz allowing an estimation of the station quality. Here we describe how we established an automatic station quality classification module using image based pattern recognition on PPSD plots. The plots were split into 4 bands: short-period characteristics (0.1-0.8 s), body wave characteristics (0.8-5 s), microseismic characteristics (5-12 s) and long-period characteristics (12-100 s). The module sqeval connects to a SeedLink server, checks available stations, requests PPSD plots through the Mustang service from IRIS or PQLX/SQLX or from GIS (gempa Image Server), a module to generate different kind of images as trace plots, map plots, helicorder plots or PPSD plots. It compares the image based quality patterns for the different period bands with the retrieved PPSD plot. The quality of a station is divided into 5 classes for each of the 4 bands. Classes A, B, C, D define regular quality between LNM and HNM while the fifth class represents out of order stations with gain problems, missing data etc. Over all period bands about 100 different patterns are required to classify most of the stations available on the

  2. Allowing for the effect of external forces in the protection of nuclear power stations. Protecting EDF's nuclear power stations from earthquakes

    International Nuclear Information System (INIS)

    Betbeder-Matibet, J.

    1985-01-01

    This paper describes the method adopted to determine the seismic level to be allowed for on a given site. One goes on to summarise the general rules applied to protect nuclear power stations against earthquakes and traces the pattern of studies carried out to determine the stresses to which plants can be subjected. Finally, one examines the consequences which allowing for earthquakes have on the design of engineering work and equipment [fr

  3. Micro-seismic earthquakes characteristics at natural and exploited hydrothermal systems in West Java, Indonesia

    Science.gov (United States)

    Jousset, P. G.; Jaya, M. S.; Sule, R.; Diningrat, W.; Gassner, A.; Akbar, F.; Ryannugroho, R.; Hendryana, A.; Kusnadi, Y.; Syahbana, D.; Nugraha, A. D.; Umar, M.; Indrinanto, Y.; Erbas, K.

    2013-12-01

    The assessment of geothermal resources requires the understanding of the structure and the dynamics of geothermal reservoirs. We deployed a multidisciplinary geophysical network around geothermal areas in the south of Bandung, West Java, Indonesia. The first deployment included a network of 30 broadband and 4 short-period seismic stations with Güralp and Trillium sensors (0.008 - 100 Hz) since October 2012. In a second step, we extended the network in June 2013 with 16 short-period (1 Hz) seismometers. We describe the set-up of the seismic networks and discuss first observations and results. The co-existence of a large variety of intense surface manifestations like geysers, hot-steaming grounds, hot water pools, and active volcanoes suggest an intimate coupling between volcanic, tectonic and hydrothermal processes in this area. Preliminary location of earthquakes is performed using a non-linear algorithm, which allows us to define at least 3 seismic clusters. We discuss this seismic pattern within the geothermal fields.

  4. Concordia, Antarctica, seismic experiment for the International Polar Year (CASE-IPY

    Directory of Open Access Journals (Sweden)

    Alessia Maggi

    2014-06-01

    Full Text Available The CASE-IPY project, part of the larger POLENET initiative of geophysical observations for the International Polar Year, was built on our extensive experience of running seismological stations in Antarctica, both on rock sites (Dumont d’Urville station, and directly on the ice plateau (Concordia station. For CASE-IPY, we deployed 8 temporary seismic stations on the Antarctic plateau: 3 situated near Concordia itself (starting 2008, and the other 5 regularly spaced between Concordia and Vostok (2010-2012, following the maximum in ice topography. The technical problems we have encountered in our field deployments were essentially due to a combination of extreme environmental conditions and isolation of deployment sites. The 3 stations near Concordia were used as test sites to experiment different solutions, and to converge on a design for the 5 main stations. Results from the nearest stations, which transmit data regularly to Concordia, are very promising. The data recorded by our stations will be distributed widely in the scientific community. We expect them to be exploited essentially for structural studies involving Antarctica itself (its ice-cap, crust and lithosphere via receiver functions, noise correlation, and surface-wave tomography, but also for studies of the Earth’s core.

  5. Dark Fiber and Distributed Acoustic Sensing: Applications to Monitoring Seismicity and Near-Surface Properties

    Science.gov (United States)

    Ajo Franklin, J. B.; Lindsey, N.; Dou, S.; Freifeld, B. M.; Daley, T. M.; Tracy, C.; Monga, I.

    2017-12-01

    "Dark Fiber" refers to the large number of fiber-optic lines installed for telecommunication purposes but not currently utilized. With the advent of distributed acoustic sensing (DAS), these unused fibers have the potential to become a seismic sensing network with unparalleled spatial extent and density with applications to monitoring both natural seismicity as well as near-surface soil properties. While the utility of DAS for seismic monitoring has now been conclusively shown on built-for-purpose networks, dark fiber deployments have been challenged by the heterogeneity of fiber installation procedures in telecommunication as well as access limitations. However, the potential of telecom networks to augment existing broadband monitoring stations provides a strong incentive to explore their utilization. We present preliminary results demonstrating the application of DAS to seismic monitoring on a 20 km run of "dark" telecommunications fiber between West Sacramento, CA and Woodland CA, part of the Dark Fiber Testbed maintained by the DOE's ESnet user facility. We show a small catalog of local and regional earthquakes detected by the array and evaluate fiber coupling by using variations in recorded frequency content. Considering the low density of broadband stations across much of the Sacramento Basin, such DAS recordings could provide a crucial data source to constrain small-magnitude local events. We also demonstrate the application of ambient noise interferometry using DAS-recorded waveforms to estimate soil properties under selected sections of the dark fiber transect; the success of this test suggests that the network could be utilized for environmental monitoring at the basin scale. The combination of these two examples demonstrates the exciting potential for combining DAS with ubiquitous dark fiber to greatly extend the reach of existing seismic monitoring networks.

  6. A combined method to calculate co-seismic displacements through strong motion acceleration baseline correction

    Science.gov (United States)

    Zhan, W.; Sun, Y.

    2015-12-01

    High frequency strong motion data, especially near field acceleration data, have been recorded widely through different observation station systems among the world. Due to tilting and a lot other reasons, recordings from these seismometers usually have baseline drift problems when big earthquake happens. It is hard to obtain a reasonable and precision co-seismic displacement through simply double integration. Here presents a combined method using wavelet transform and several simple liner procedures. Owning to the lack of dense high rate GNSS data in most of region of the world, we did not contain GNSS data in this method first but consider it as an evaluating mark of our results. This semi-automatic method unpacks a raw signal into two portions, a summation of high ranks and a low ranks summation using a cubic B-spline wavelet decomposition procedure. Independent liner treatments are processed against these two summations, which are then composed together to recover useable and reasonable result. We use data of 2008 Wenchuan earthquake and choose stations with a near GPS recording to validate this method. Nearly all of them have compatible co-seismic displacements when compared with GPS stations or field survey. Since seismometer stations and GNSS stations from observation systems in China are sometimes quite far from each other, we also test this method with some other earthquakes (1999 Chi-Chi earthquake and 2011 Tohoku earthquake). And for 2011 Tohoku earthquake, we will introduce GPS recordings to this combined method since the existence of a dense GNSS systems in Japan.

  7. An automated multi-scale network-based scheme for detection and location of seismic sources

    Science.gov (United States)

    Poiata, N.; Aden-Antoniow, F.; Satriano, C.; Bernard, P.; Vilotte, J. P.; Obara, K.

    2017-12-01

    We present a recently developed method - BackTrackBB (Poiata et al. 2016) - allowing to image energy radiation from different seismic sources (e.g., earthquakes, LFEs, tremors) in different tectonic environments using continuous seismic records. The method exploits multi-scale frequency-selective coherence in the wave field, recorded by regional seismic networks or local arrays. The detection and location scheme is based on space-time reconstruction of the seismic sources through an imaging function built from the sum of station-pair time-delay likelihood functions, projected onto theoretical 3D time-delay grids. This imaging function is interpreted as the location likelihood of the seismic source. A signal pre-processing step constructs a multi-band statistical representation of the non stationary signal, i.e. time series, by means of higher-order statistics or energy envelope characteristic functions. Such signal-processing is designed to detect in time signal transients - of different scales and a priori unknown predominant frequency - potentially associated with a variety of sources (e.g., earthquakes, LFE, tremors), and to improve the performance and the robustness of the detection-and-location location step. The initial detection-location, based on a single phase analysis with the P- or S-phase only, can then be improved recursively in a station selection scheme. This scheme - exploiting the 3-component records - makes use of P- and S-phase characteristic functions, extracted after a polarization analysis of the event waveforms, and combines the single phase imaging functions with the S-P differential imaging functions. The performance of the method is demonstrated here in different tectonic environments: (1) analysis of the one year long precursory phase of 2014 Iquique earthquake in Chile; (2) detection and location of tectonic tremor sources and low-frequency earthquakes during the multiple episodes of tectonic tremor activity in southwestern Japan.

  8. Seismic waves travel-time curve, basing on the results of signal detection from chemical explosions detonated at Semipalatinsk Test Site

    International Nuclear Information System (INIS)

    Mikhajlova, N.N.; Aristova, I.L.; Germanova, T.I.

    2001-01-01

    A large amount of digital seismic data from the permanent and temporary seismic stations was acquired in the result of detonation of large chemical explosions at Semipalatinsk Test Site. All the records were collected, systematized and processed, and databases were created. Travel-time curves for regional Pn, Pg, Sn and Lg waves were created and compared with the ones used in routine earthquake processing practice. (author)

  9. 3D absolute hypocentral determination - 13 years of seismicity in Ecuadorian subduction zone

    Science.gov (United States)

    Font, Yvonne; Segovia, Monica; Theunissen, Thomas

    2010-05-01

    In Ecuador, the Nazca plate is subducting beneath the North Andean Block. This subduction triggered, during the last century, 4 major earthquakes of magnitude greater than 7.7. Between 1994 and 2007, the Geophysical Institute (Escuela National Politecnica, Quito) recorded about 40 000 events in whole Ecuador ranging from Mb 1.5 to 6.9. Unfortunately, the local network shows great density discrepancy between the Coastal and Andean regions where numerous stations were installed to survey volcanic activity. Consequently, seismicity in and around the interplate seismogenic zone - producer of the most destructive earthquakes and tsunamis - is not well constrained. This study aims to improve the location of 13 years seismicity occurred during an interseismic period in order to better localize the seismic deformation and gaps. The first step consists in the construction of a 3D "georealistic" velocity model. Because local tomography cannot provide satisfactory model, we combined all local crustal/lithospheric information on the geometry and velocity properties of different geological units. Those information cover the oceanic Nazca plate and sedimentary coverture the subducting plate dip angle; the North Andean Block margin composed of accreted oceanic plateaus (the Moho depth is approximated using gravity modeling); the metamorphic volcanic chain (oceanic nature for the occidental cordillera and inter-andean valley, continental one for the oriental cordillera); The continental Guyana shield and sedimentary basins. The resulting 3D velocity model extends from 2°N to 6.5°S and 277°E to 283°E and reaches a depth of 300 km. It is discretized in constant velocity blocks of 12 x 12 x 3 km in x, y and z, respectively. The second step consists in selecting an adequate sub-set of seismic stations in order to correct the effect of station density disequilibrium between coastal and volcanic regions. Consequently, we only keep the most representative volcanic stations in terms

  10. PH5: HDF5 Based Format for Integrating and Archiving Seismic Data

    Science.gov (United States)

    Hess, D.; Azevedo, S.; Falco, N.; Beaudoin, B. C.

    2017-12-01

    PH5 is a seismic data format created by IRIS PASSCAL using HDF5. Building PH5 on HDF5 allows for portability and extensibility on a scale that is unavailable in older seismic data formats. PH5 is designed to evolve to accept new data types as they become available in the future and to operate on a variety of platforms (i.e. Mac, Linux, Windows). Exemplifying PH5's flexibility is the evolution from just handling active source seismic data to now including passive source, onshore-offshore, OBS and mixed source seismic data sets. In PH5, metadata is separated from the time series data and stored in a size and performance efficient manner that also allows for easy user interaction and output of the metadata in a format appropriate for the data set. PH5's full-fledged "Kitchen Software Suite" comprises tools for data ingestion (e.g. RefTek, SEG-Y, SEG-D, SEG-2, MSEED), meta-data management, QC, waveform viewing, and data output. This software suite not only includes command line and GUI tools for interacting with PH5, it is also a comprehensive Python package to support the creation of software tools by the community to further enhance PH5. The PH5 software suite is currently being used in multiple capacities, including in-field for creating archive ready data sets as well as by the IRIS Data Management Center (DMC) to offer an FDSN compliant set of web services for serving PH5 data to the community in a variety of standard data and meta-data formats (i.e. StationXML, QuakeML, EventXML, SAC + Poles and Zeroes, MiniSEED, and SEG-Y) as well as StationTXT and ShotText formats. These web services can be accessed via standard FDSN clients such as ObsPy, irisFetch.m, FetchData, and FetchMetadata. This presentation will highlight and demonstrate the benefits of PH5 as a next generation adaptable and extensible data format for use in both archiving and working with seismic data.

  11. Applications of seismic spatial wavefield gradient and rotation data in exploration seismology

    Science.gov (United States)

    Schmelzbach, C.; Van Renterghem, C.; Sollberger, D.; Häusler, M.; Robertsson, J. O. A.

    2017-12-01

    Seismic spatial wavefield gradient and rotation data have the potential to open up new ways to address long-standing problems in land-seismic exploration such as identifying and separating P-, S-, and surface waves. Gradient-based acquisition and processing techniques could enable replacing large arrays of densely spaced receivers by sparse spatially-compact receiver layouts or even one single multicomponent station with dedicated instruments (e.g., rotational seismometers). Such approaches to maximize the information content of single-station recordings are also of significant interest for seismic measurements at sites with limited access such as boreholes, the sea bottom, and extraterrestrial seismology. Arrays of conventional three-component (3C) geophones enable measuring not only the particle velocity in three dimensions but also estimating their spatial gradients. Because the free-surface condition allows to express vertical derivatives in terms of horizontal derivatives, the full gradient tensor and, hence, curl and divergence of the wavefield can be computed. In total, three particle velocity components, three rotational components, and divergence, result seven-component (7C) seismic data. Combined particle velocity and gradient data can be used to isolate the incident P- or S-waves at the land surface or the sea bottom using filtering techniques based on the elastodynamic representation theorem. Alternatively, as only S-waves exhibit rotational motion, rotational measurements can directly be used to identify S-waves. We discuss the derivations of the gradient-based filters as well as their application to synthetic and field data, demonstrating that rotational data can be of particular interest to S-wave reflection and P-to-S-wave conversion imaging. The concept of array-derived gradient estimation can be extended to source arrays as well. Therefore, source arrays allow us to emulate rotational (curl) and dilatational (divergence) sources. Combined with 7C

  12. RTX Correction Accuracy and Real-Time Data Processing of the New Integrated SeismoGeodetic System with Real-Time Acceleration and Displacement Measurements for Earthquake Characterization Based on High-Rate Seismic and GPS Data

    Science.gov (United States)

    Zimakov, L. G.; Raczka, J.; Barrientos, S. E.

    2016-12-01

    We will discuss and show the results obtained from an integrated SeismoGeodetic System, model SG160-09, installed in the Chile (Chilean National Network), Italy (University of Naples Network), and California. The SG160-09 provides the user high rate GNSS and accelerometer data, full epoch-by-epoch measurement integrity and the ability to create combined GNSS and accelerometer high-rate (200Hz) displacement time series in real-time. The SG160-09 combines seismic recording with GNSS geodetic measurement in a single compact, ruggedized case. The system includes a low-power, 220-channel GNSS receiver powered by the latest Trimble-precise Maxwell™6 technology and supports tracking GPS, GLONASS and Galileo signals. The receiver incorporates on-board GNSS point positioning using Real-Time Precise Point Positioning (PPP) technology with satellite clock and orbit corrections delivered over IP networks. The seismic recording includes an ANSS Class A, force balance accelerometer with the latest, low power, 24-bit A/D converter, producing high-resolution seismic data. The SG160-09 processor acquires and packetizes both seismic and geodetic data and transmits it to the central station using an advanced, error-correction protocol providing data integrity between the field and the processing center. The SG160-09 has been installed in three seismic stations in different geographic locations with different Trimble global reference stations coverage The hardware includes the SG160-09 system, external Zephyr Geodetic-2 GNSS antenna, both radio and high-speed Internet communication media. Both acceleration and displacement data was transmitted in real-time to the centralized Data Acquisition Centers for real-time data processing. Command/Control of the field station and real-time GNSS position correction are provided via the Pivot platform. Data from the SG160-09 system was used for seismic event characterization along with data from traditional seismic and geodetic stations

  13. Caltech/USGS Southern California Seismic Network: Recent Developments

    Science.gov (United States)

    Bhadha, R.; Chen, S.; Crummey, J.; Hauksson, E.; Solanki, K.; Thomas, V. I.; Watkins, M.; Yip, R.; Yu, E.; Given, D.; Peats, R.; Schwarz, S.

    2010-12-01

    The SCSN is the modern digital ground motion seismic network in Southern California and performs the following tasks: 1) Operates remote seismic stations and the central data processing systems in Pasadena; 2) Generates and reports real-time products including location, magnitude, ShakeMap, and others; 3) Responds to FEMA, CalEMA, media, and public inquiries about earthquakes; 4) Manages the production, archival, and distribution of waveforms, phase picks, and other data at the SCEDC; 5) Contributes to development and maintenance of the ANSS Quake Monitoring System (AQMS) software to add new features and improve robustness; 6) Supports the deployment of AQMS to other ANSS member regional seismic networks. The public regularly accesses the CISN, SCSN, and SCEDC web pages for up-to-date quake info and more than 230,000 users subscribe to the Electronic Notification System (ENS) which sends rapid notifications via email and cell phones. We distribute our products via Internet (EIDS), email, and paging, to USGS in Reston and Golden, FEMA, CalEMA, local governments, partner members, and other subscribers. We have developed CISN Display and provide ShakeCast for customers who require real-time earthquake information. The SCSN also exchanges waveform, phase pick, and amplitude data in real-time with several other partner networks, including Menlo Park, UCB, UNR, Anza network, the Tsunami Warning Centers, IRIS, and the NEIC. We operate a number of 24/7 on-call rotations to provide quick response to verify seismic events as well as addressing systems and telemetry issues. As part of our goals to improve quality, robustness, and coverage, some of our recent efforts include: 1) Converting the digital stations in the network to Q330 dataloggers; 2) Developing command and control capabilities such as automated mass re-centering; 3) Migration from serial to Ethernet communications; 4) Clustering of data acquisition servers for fail-over to improve data availability; 5) Use of

  14. Observed seismic and infrasonic signals around the Hakone volcano -Discussion based on a finite-difference calculation-

    Science.gov (United States)

    Wakamatu, S.; Kawakata, H.; Hirano, S.

    2017-12-01

    Observation and analysis of infrasonic waves are important for volcanology because they could be associated with mechanisms of volcanic tremors and earthquakes (Sakai et al., 2000). Around the Hakone volcano area, Japan, infrasonic waves had been observed many times in 2015 (Yukutake et al., 2016, JpGU). In the area, seismometers have been installed more than microphones, so that analysis of seismograms may also contribute to understanding some characteristics of the infrasonic waves. In this study, we focused on the infrasonic waves on July 1, 2015, at the area and discussed their propagation. We analyzed the vertical component of seven seismograms and two infrasound records; instruments for these data have been installed within 5 km from the vent emerged in the June 2015 eruption(HSRI, 2015). We summarized distances of the observation points from the vent and appearance of the signals in the seismograms and the microphone records in Table 1. We confirmed that, when the OWD microphone(Fig1) observed the infrasonic waves, seismometers of the OWD and the KIN surface seismic stations(Fig1) recorded pulse-like signals repeatedly while the other five buried seismometers did not. At the same time, the NNT microphone(Fig1) recorded no more than unclear signals despite the shorter distance to the vent than that of the KIN station. We found that the appearance of pulse-like signals at the KIN seismic station usually 10-11 seconds delay after the appearance at the OWD seismic station. The distance between these two stations is 3.5km, so that the signals in seismograms could represent propagation of the infrasonic waves rather than the seismic waves. If so, however, the infrasound propagation could be influenced by the topography of the area because the signals are unclear in the NNT microphone record.To validate the above interpretation, we simulated the diffraction of the infrasonic waves due to the topography. We executed a 3-D finite-difference calculation by

  15. Virtual Seismic Observation (VSO) with Sparsity-Promotion Inversion

    Science.gov (United States)

    Tiezhao, B.; Ning, J.; Jianwei, M.

    2017-12-01

    Large station interval leads to low resolution images, sometimes prevents people from obtaining images in concerned regions. Sparsity-promotion inversion, a useful method to recover missing data in industrial field acquisition, can be lent to interpolate seismic data on none-sampled sites, forming Virtual Seismic Observation (VSO). Traditional sparsity-promotion inversion suffers when coming up with large time difference in adjacent sites, which we concern most and use shift method to improve it. The procedure of the interpolation is that we first employ low-pass filter to get long wavelength waveform data and shift the waveforms of the same wave in different seismograms to nearly same arrival time. Then we use wavelet-transform-based sparsity-promotion inversion to interpolate waveform data on none-sampled sites and filling a phase in each missing trace. Finally, we shift back the waveforms to their original arrival times. We call our method FSIS (Filtering, Shift, Interpolation, Shift) interpolation. By this way, we can insert different virtually observed seismic phases into none-sampled sites and get dense seismic observation data. For testing our method, we randomly hide the real data in a site and use the rest to interpolate the observation on that site, using direct interpolation or FSIS method. Compared with directly interpolated data, interpolated data with FSIS can keep amplitude better. Results also show that the arrival times and waveforms of those VSOs well express the real data, which convince us that our method to form VSOs are applicable. In this way, we can provide needed data for some advanced seismic technique like RTM to illuminate shallow structures.

  16. Statistical analysis of laser-interferometric detector Dylkin-1 data and data on seismic activity

    International Nuclear Information System (INIS)

    Kirillov, R S; Bochkarev, V V; Dulkyn, Academy of Sciences of the Republic of Tatarstan (Russian Federation))" data-affiliation=" (Scientific Center of Gravitational-Wave Research Dulkyn, Academy of Sciences of the Republic of Tatarstan (Russian Federation))" >Skochilov, A F

    2014-01-01

    This work presents statistical analysis of data collected from laser interferometric detector ''Dylkin-1'' and nearby seismic stations. The final goal of Dylkin project consists in creating detector of theoretically predicted gravitational waves produced by binary relativistic astrophysical objects. Currently, works are underway to improve sensitivity of detector by 2-3 orders. The goals of this research were to test isolation of detector from noise caused by seismic waves and to find out whether it is sensitive to variations in the gradient of gravitational potential (acceleration of free fall) caused by free Earth oscillations. Noise isolation has been tested by comparing energy of signals during significant seismic events. Sensitivity to variations in acceleration of free fall has been tested by means of cross-spectral analysis

  17. Technique and the scheme of engineering-seismometric supervision over seismic events on large dams

    Energy Technology Data Exchange (ETDEWEB)

    Karapetyan, S.; Babayan, T.; Mkrtchyan, G. [National Academy of Sciences of the Republic of Armenia (Armenia). Inst. of Geophysics and Engineering Seismology

    2004-07-01

    A network of engineering-seismometric monitoring stations have been installed at the Tavshout dam in a seismically active region of Armenia. The 37 meter high embankment dam consists of gravel-pebbles with a core of sandy clay. Recent earthquakes have presented a direct hazard for the dam and its water reservoir. In order to determine the degree of seismic hazard and prevention, it is necessary to study the interaction between the ground and the foundation of the dam. The seismometers were fixed at three points both on the foundation and the ground to obtain information on the whole route of seismic waves and to define the geology based amplification factors using empirical equations. The system of engineering-seismometric observations included a network of seismometric instruments, communications and a recording complex. 4 refs., 14 figs.

  18. Hazard Monitoring of Growing Lava Flow Fields Using Seismic Tremor

    Science.gov (United States)

    Eibl, E. P. S.; Bean, C. J.; Jónsdottir, I.; Hoskuldsson, A.; Thordarson, T.; Coppola, D.; Witt, T.; Walter, T. R.

    2017-12-01

    An effusive eruption in 2014/15 created a 85 km2 large lava flow field in a remote location in the Icelandic highlands. The lava flows did not threaten any settlements or paved roads but they were nevertheless interdisciplinarily monitored in detail. Images from satellites and aircraft, ground based video monitoring, GPS and seismic recordings allowed the monitoring and reconstruction of a detailed time series of the growing lava flow field. While the use of satellite images and probabilistic modelling of lava flows are quite common tools to monitor the current and forecast the future growth direction, here we show that seismic recordings can be of use too. We installed a cluster of seismometers at 15 km from the vents and recorded the ground vibrations associated with the eruption. This seismic tremor was not only generated below the vents, but also at the edges of the growing lava flow field and indicated the parts of the lava flow field that were most actively growing. Whilst the time resolution is in the range of days for satellites, seismic stations easily sample continuously at 100 Hz and could therefore provide a much better resolution and estimate of the lava flow hazard in real-time.

  19. IAEA specialists' meeting on seismic isolation technology. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1992-07-01

    design, fabrication, testing of seismic isolation elements and systems, the capabilities of analytical codes and models and status of validation. The presentations provided by the participating countries indicated that seismic isolation technology has sufficiently advanced to make it an attractive feature in advanced nuclear power stations for mitigation of severe earthquakes. Indeed, advanced reactor concept evaluation and studies in Canada, Europe, Japan and the USA include horizontal seismic isolation and in some cases a combination of horizontal and vertical seismic isolation. The development of seismic isolation elements/bearings seems to be progressing towards standardized designs. The testing programs indicate high quality and consistency in the bearing manufacturing process. Significant progress has been achieved in providing reliable bonding of elastomer layers and steel laminations that is stronger than the rubber itself. Another important aspect is the demonstrated long term durability of steel-laminated elastomer bearings under sustained loading conditions. The development of design codes and standards for seismic isolation is proceeding independently in the countries applying this technology consistent with the individual frameworks of regulations. In a future meeting it would be of interest to compare key elements of the design codes and standards in particular as they relate to safety aspects.

  20. IAEA specialists' meeting on seismic isolation technology. Proceedings

    International Nuclear Information System (INIS)

    1992-01-01

    design, fabrication, testing of seismic isolation elements and systems, the capabilities of analytical codes and models and status of validation. The presentations provided by the participating countries indicated that seismic isolation technology has sufficiently advanced to make it an attractive feature in advanced nuclear power stations for mitigation of severe earthquakes. Indeed, advanced reactor concept evaluation and studies in Canada, Europe, Japan and the USA include horizontal seismic isolation and in some cases a combination of horizontal and vertical seismic isolation. The development of seismic isolation elements/bearings seems to be progressing towards standardized designs. The testing programs indicate high quality and consistency in the bearing manufacturing process. Significant progress has been achieved in providing reliable bonding of elastomer layers and steel laminations that is stronger than the rubber itself. Another important aspect is the demonstrated long term durability of steel-laminated elastomer bearings under sustained loading conditions. The development of design codes and standards for seismic isolation is proceeding independently in the countries applying this technology consistent with the individual frameworks of regulations. In a future meeting it would be of interest to compare key elements of the design codes and standards in particular as they relate to safety aspects

  1. National Earthquake Information Center Seismic Event Detections on Multiple Scales

    Science.gov (United States)

    Patton, J.; Yeck, W. L.; Benz, H.; Earle, P. S.; Soto-Cordero, L.; Johnson, C. E.

    2017-12-01

    The U.S. Geological Survey National Earthquake Information Center (NEIC) monitors seismicity on local, regional, and global scales using automatic picks from more than 2,000 near-real time seismic stations. This presents unique challenges in automated event detection due to the high variability in data quality, network geometries and density, and distance-dependent variability in observed seismic signals. To lower the overall detection threshold while minimizing false detection rates, NEIC has begun to test the incorporation of new detection and picking algorithms, including multiband (Lomax et al., 2012) and kurtosis (Baillard et al., 2014) pickers, and a new bayesian associator (Glass 3.0). The Glass 3.0 associator allows for simultaneous processing of variably scaled detection grids, each with a unique set of nucleation criteria (e.g., nucleation threshold, minimum associated picks, nucleation phases) to meet specific monitoring goals. We test the efficacy of these new tools on event detection in networks of various scales and geometries, compare our results with previous catalogs, and discuss lessons learned. For example, we find that on local and regional scales, rapid nucleation of small events may require event nucleation with both P and higher-amplitude secondary phases (e.g., S or Lg). We provide examples of the implementation of a scale-independent associator for an induced seismicity sequence (local-scale), a large aftershock sequence (regional-scale), and for monitoring global seismicity. Baillard, C., Crawford, W. C., Ballu, V., Hibert, C., & Mangeney, A. (2014). An automatic kurtosis-based P-and S-phase picker designed for local seismic networks. Bulletin of the Seismological Society of America, 104(1), 394-409. Lomax, A., Satriano, C., & Vassallo, M. (2012). Automatic picker developments and optimization: FilterPicker - a robust, broadband picker for real-time seismic monitoring and earthquake early-warning, Seism. Res. Lett. , 83, 531-540, doi: 10

  2. IEEE C37.98-1978: IEEE standard seismic testing of relays

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This standard specifies the procedures to be used in the seismic testing of relays used in power system facilities. The standard is concerned with the determination of the seismic fragility level of relays and also gives recommendations for proof testing. The purpose of this standard is to establish procedures for determining the seismic capabilities of protective and auxiliary relays. These procedures employ what has been called fragility testing in ANSI/IEEE Std 344-1975, Recommended Practices for Seismic Qualification of Class 1E Equipment for Nuclear Power Generating Stations. In order to define the conditions for fragility testing of relays, parameters in three separate areas must be specified. In general they are: (1) the electrical settings and inputs to the relay, and other information to define its conditions during the test; (2) the change in state, deviation in operating characteristics or tolerances, or other change of performance of the relay which constitutes failure; (3) the seismic vibration environment to be imposed during the test. Since it is not possible to define the conditions for every conceivable application for all relays, those parameters, which in practice encompass the majority of applications, have been specified in this standard. When the application of the relay is other than as specified under any of (1), (2), and (3), or if it is not practical to apply existing results of fragility tests to that new case

  3. Seismic qualification of safety-related instrumentation cabinets for nuclear generating stations

    International Nuclear Information System (INIS)

    Sauve, R.G.; Bell, R.P.; Cuttler, J.M.

    1979-06-01

    The problem of seismically qualifying different electrical instruments mounted in cabinets of a standard design is discussed and the following economical approach is described in detail. An analytical model of the cabinet structure is developed and validated by comparison with the results of shake table tests on a prototype cabinet. Modal analysis is then used to calculate the input spectra for shake table tests to qualify the individual instruments that are mounted at the required elevations in the cabinet. The worst input spectrum, appropriate to qualify each instrument, is then specified to the suppliers. This approach avoids the need to test each cabinet configuration in an assembled state in order to qualify it. (auth)

  4. A procedure for seismic risk reduction in Campania Region

    International Nuclear Information System (INIS)

    Zuccaro, G.; Palmieri, M.; Cicalese, S.; Grassi, V.; Rauci, M.; Maggio, F.

    2008-01-01

    The Campania Region has set and performed a peculiar procedure in the field of seismic risk reduction. Great attention has been paid to public strategic buildings such as town halls, civil protection buildings and schools. The Ordinance 3274 promulgate in the 2004 by the Italian central authority obliged the owners of strategic buildings to perform seismic analyses within 2008 in order to check the safety of the structures and the adequacy to the use. In the procedure the Campania region, instead of the local authorities, ensure the complete drafting of seismic checks through financial resources of the Italian Government. A regional scientific technical committee has been constituted, composed of scientific experts, academics in seismic engineering. The committee has drawn up guidelines for the processing of seismic analyses. At the same time, the Region has issued a public competition to select technical seismic engineering experts to appoint seismic analysis in accordance with guidelines. The scientific committee has the option of requiring additional documents and studies in order to approve the safety checks elaborated. The Committee is supported by a technical and administrative secretariat composed of a group of expert in seismic engineering. At the moment several seismic safety checks have been completed. The results will be presented in this paper. Moreover, the policy to mitigate the seismic risk, set by Campania region, was to spend the most of the financial resources available on structural strengthening of public strategic buildings rather than in safety checks. A first set of buildings of which the response under seismic action was already known by data and studies of vulnerability previously realised, were selected for immediate retrofitting designs. Secondly, an other set of buildings were identified for structural strengthening. These were selected by using the criteria specified in the Guide Line prepared by the Scientific Committee and based on

  5. A procedure for seismic risk reduction in Campania Region

    Science.gov (United States)

    Zuccaro, G.; Palmieri, M.; Maggiò, F.; Cicalese, S.; Grassi, V.; Rauci, M.

    2008-07-01

    The Campania Region has set and performed a peculiar procedure in the field of seismic risk reduction. Great attention has been paid to public strategic buildings such as town halls, civil protection buildings and schools. The Ordinance 3274 promulgate in the 2004 by the Italian central authority obliged the owners of strategic buildings to perform seismic analyses within 2008 in order to check the safety of the structures and the adequacy to the use. In the procedure the Campania region, instead of the local authorities, ensure the complete drafting of seismic checks through financial resources of the Italian Government. A regional scientific technical committee has been constituted, composed of scientific experts, academics in seismic engineering. The committee has drawn up guidelines for the processing of seismic analyses. At the same time, the Region has issued a public competition to select technical seismic engineering experts to appoint seismic analysis in accordance with guidelines. The scientific committee has the option of requiring additional documents and studies in order to approve the safety checks elaborated. The Committee is supported by a technical and administrative secretariat composed of a group of expert in seismic engineering. At the moment several seismic safety checks have been completed. The results will be presented in this paper. Moreover, the policy to mitigate the seismic risk, set by Campania region, was to spend the most of the financial resources available on structural strengthening of public strategic buildings rather than in safety checks. A first set of buildings of which the response under seismic action was already known by data and studies of vulnerability previously realised, were selected for immediate retrofitting designs. Secondly, an other set of buildings were identified for structural strengthening. These were selected by using the criteria specified in the Guide Line prepared by the Scientific Committee and based on

  6. Recent seismicity of the «Acque Albule» travertine basin

    Directory of Open Access Journals (Sweden)

    A. Marchetti

    2002-06-01

    Full Text Available The seismic period which occurred in a portion of Guidonia Montecelio and Tivoli territory, two towns situated about twenty kilometres NE of Rome, affected four areas with a high density of population: Guidonia, Collefiorito, Villalba and Bagni di Tivoli. Even though the events had a very low magnitude (less than 3.0, local phenomena, like rumbles and strong vibrations of the ground, frightened inhabitants also because some months before (January 26, 2001 in a village named Marcellina situated a few kilometres away from Guidonia, a large sinkhole (600 m had appeared without fore signals. The «Istituto Nazionale di Geofisica e Vulcanologia» (INGV installed some digital stations that monitored the seismic phenomena. This paper has the aim to process all the information acquired during the period, both from the micro and macro seismic point of view, in order to explain the phenomenology that involved the area. The synergy of the two methodologies lead us to the conclusion that two different seismotectonic structures originated the events, one in an anti-apenninic direction, the other in a N-S direction.

  7. PQLX: A seismic data quality control system description, applications, and users manual

    Science.gov (United States)

    McNamara, Daniel E.; Boaz, Richard I.

    2011-01-01

    We present a detailed description and users manual for a new tool to evaluate seismic station performance and characteristics by providing quick and easy transitions between visualizations of the frequency and time domains. The software is based on the probability density functions (PDF) of power spectral densities (PSD) (McNamara and Buland, 2004) and builds on the original development of the PDF stand-alone software system (McNamara and Boaz, 2005) and the seismological data viewer application PQL (IRIS-PASSCAL Quick Look) and PQLII (available through the IRIS PASSCAL program: http://www.passcal.nmt.edu/content/pql-ii-program-viewing-data). With PQLX (PQL eXtended), computed PSDs are stored in a MySQL database, allowing a user to access specific time periods of PSDs (PDF subsets) and time series segments through a GUI-driven interface. The power of the method and software lies in the fact that there is no need to screen the data for system transients, earthquakes, or general data artifacts, because they map into a background probability level. In fact, examination of artifacts related to station operation and episodic cultural noise allow us to estimate both the overall station quality and a baseline level of Earth noise at each site. The output of this analysis tool is useful for both operational and scientific applications. Operationally, it is useful for characterizing the current and past performance of existing broadband stations, for conducting tests on potential new seismic station locations, for evaluating station baseline noise levels (McNamara and others, 2009), for detecting problems with the recording system or sensors, and for evaluating the overall quality of data and metadata. Scientifically, the tool allows for mining of PSDs for investigations on the evolution of seismic noise (for example, Aster and others, 2008; and Aster and others, 2010) and other phenomena. Currently, PQLX is operational at several organizations including the USGS National

  8. Seismicity and seismogenic structures of Central Apennines (Italy): constraints on the present-day stress field from focal mechanisms - The SLAM (Seismicity of Lazio-Abruzzo and Molise) project

    Science.gov (United States)

    Frepoli, Alberto; Battista Cimini, Giovanni; De Gori, Pasquale; De Luca, Gaetano; Marchetti, Alessandro; Montuori, Caterina; Pagliuca, Nicola

    2016-04-01

    We present new results for the microseismic activity in the Central Apennines recorded from a total of 81seismic stations. The large number of recording sites derives from the combination of temporary and permanent seismic networks operating in the study region. Between January 2009 and October 2013 we recorded 6923 earthquakes with local magnitudes ML ranging from 0.1 to 4.8. We located hypocentres by using a refined 1D crustal velocity model. The majority of the hypocenters are located beneath the axes of the Apenninic chain, while the seismic activity observed along the peri-Tyrrhenian margin is lower. The seismicity extends to a depth of 32 km; the hypocentral depth distribution exhibits a pronounced peak of seismic energy release in the depth range between 8 and 20 km. During the observation period we recorded two major seismic swarms and one seismic sequence in the Marsica-Sorano area in which we have had the largest detected magnitude (ML = 4.8). Fault plane solutions for a total of 600 earthquakes were derived from P-polarities. This new data set consists of a number of focal plane solutions that is about four times the data so far available for regional stress field study. The majority of the focal mechanisms show predominantly normal fault solutions. T-axis trends are oriented NE-SW confirming that the area is in extension. We also derived the azimuths of the principal stress axes by inverting the fault plane solutions and calculated the direction of the maximum horizontal stress, which is mainly sub-vertical oriented. The study region has been historically affected by many strong earthquakes, some of them very destructive. This work can give an important contribution to the seismic hazard assessment in an area densely populated as the city of Rome which is distant around 60 km from the main seismogenic structures of Central Apennine.

  9. An Experimental Seismic Data and Parameter Exchange System for Tsunami Warning Systems

    Science.gov (United States)

    Hoffmann, T. L.; Hanka, W.; Saul, J.; Weber, B.; Becker, J.; Heinloo, A.; Hoffmann, M.

    2009-12-01

    For several years GFZ Potsdam is operating a global earthquake monitoring system. Since the beginning of 2008, this system is also used as an experimental seismic background data center for two different regional Tsunami Warning Systems (TWS), the IOTWS (Indian Ocean) and the interim NEAMTWS (NE Atlantic and Mediterranean). The SeisComP3 (SC3) software, developed within the GITEWS (German Indian Ocean Tsunami Early Warning System) project, capable to acquire, archive and process real-time data feeds, was extended for export and import of individual processing results within the two clusters of connected SC3 systems. Therefore not only real-time waveform data are routed to the attached warning centers through GFZ but also processing results. While the current experimental NEAMTWS cluster consists of SC3 systems in six designated national warning centers in Europe, the IOTWS cluster presently includes seven centers, with another three likely to join in 2009/10. For NEAMTWS purposes, the GFZ virtual real-time seismic network (GEOFON Extended Virtual Network -GEVN) in Europe was substantially extended by adding many stations from Western European countries optimizing the station distribution. In parallel to the data collection over the Internet, a GFZ VSAT hub for secured data collection of the EuroMED GEOFON and NEAMTWS backbone network stations became operational and first data links were established through this backbone. For the Southeast Asia region, a VSAT hub has been established in Jakarta already in 2006, with some other partner networks connecting to this backbone via the Internet. Since its establishment, the experimental system has had the opportunity to prove its performance in a number of relevant earthquakes. Reliable solutions derived from a minimum of 25 stations were very promising in terms of speed. For important events, automatic alerts were released and disseminated by emails and SMS. Manually verified solutions are added as soon as they become

  10. Avoiding Service Station Fraud.

    Science.gov (United States)

    Burton, Grace M.; Burton, John R.

    1982-01-01

    High school students are warned against service station fraud. A problem-solving section is designed to help students calculate consumer costs for various fraudulent transactions. Several ways of reducing fraud or of lessening the chances of problems are noted. (MP)

  11. A Study of Small Magnitude Seismic Events During 1961-1989 on and near the Semipalatinsk Test Site, Kazakhstan

    Science.gov (United States)

    Khalturin, V. I.; Rautian, T. G.; Richards, P. G.

    - Official Russian sources in 1996 and 1997 have stated that 340 underground nuclear tests (UNTs) were conducted during 1961-1989 at the Semipalatinsk Test Site (STS) in Eastern Kazakhstan. Only 271 of these nuclear tests appear to have been described with well-determined origin time, coordinates and magnitudes in the openly available technical literature. Thus, good open documentation has been lacking for 69 UNTs at STS.The main goal of our study was to provide detections, estimates of origin time and location, and magnitudes, for as many of these previously undocumented events as possible. We used data from temporary and permanent seismographic stations in the former USSR at distances from 500km to about 1500km from STS. As a result, we have been able to assign magnitude for eight previously located UNTs whose magnitude was not previously known. For 31 UNTs, we have estimated origin time an d assigned magnitude - and for 19 of these 31 we have obtained locations based on seismic signals. Of the remaining 30 poorly documented UNTs, 15 had announced yields that were less than one ton, and 13 occurred simultaneously with another test which was detected. There are only two UNTs, for which the announced yield exceeds one ton and we have been unable to find seismic signals.Most of the newly detected and located events were sub-kiloton. Their magnitudes range from 2.7 up to 5.1 (a multi-kiloton event on 1965 Feb. 4 that was often obscured at teleseismic stations by signals from an earthquake swarm in the Aleutians).For 17 small UNTs at STS, we compare the locations (with their uncertainties) that we had earlier determined in 1994 from analysis of regional seismic waves, with ground-truth information obtained in 1998. The average error of the seismically-determined locations is only about 5km. The ground-truth location is almost alw ays within the predicted small uncertainty of the seismically-determined location.Seismically-determined yield estimates are in good

  12. Investigating subduction reversal in Papua New Guinea from automatic analysis of seismicity recorded on a temporary local network

    Science.gov (United States)

    Hicks, S. P.; Harmon, N.; Rychert, C.; Tharimena, S.; Bogiatzis, P.; Savage, B.; Shen, Y.; Baillard, C.

    2017-12-01

    The area of Papua New Guinea is one of the most seismically active regions on the planet. Seismicity in the region results from oblique convergence between the Pacific and India-Australia plates, with deformation occurring across a broad region involving several microplates. The region gives an excellent natural laboratory to test geodynamic models of subduction polarity reversal, microplate interaction, and to delineate the structure of subducting plates and relic structures at depth. However, a lack of permanent seismic stations means that routine earthquake locations for small to intermediate sized earthquakes have significant location errors. In 2014, we deployed a temporary network of eight broadband stations on islands in eastern Papua New Guinea to record ongoing seismic deformation. The network straddles a complex region where subduction of the Solomon plate occurs to the south and possible subduction of the Ontong-Java plateau occurs to the north. The stations were installed for 27 months. During the deployment period, there were 13 M>6.5 earthquakes in the area, including M7.5 doublet events in 2015, giving a rich seismic dataset. A high-quality catalogue of local events was formed by a multi-step process. Using the scanloc module of SeisComp3, we first detect P-onsets using a STA/LTA detection. Once clusters of P onsets are found, S-wave picks are incorporated based on a pre-defined window length of maximum S-P time. Groups of onsets are then associated to events, giving us a starting catalogue of 269 events (1765 P-onsets) with minimum magnitude of M 3.5. In a second step, we refine onset times using a Kurtosis picker to improve location accuracy. To form robust hypocentral locations using an appropriate structural model for the area and to constrain crust and mantle structure in the region, we derive a minimum 1-D velocity model using the VELEST program. We use a starting model from Abers et al. (1991) and we restrict our catalogue to events with an

  13. Gaps, tears and seismic anisotropy around the subducting slabs of the Antilles

    Science.gov (United States)

    Schlaphorst, David; Kendall, J.-Michael; Baptie, Brian; Latchman, Joan L.; Tait, Steve

    2017-02-01

    Seismic anisotropy in and beneath the subducting slabs of the Antilles is investigated using observations of shear-wave splitting. We use a combination of teleseismic and local events recorded at three-component broadband seismic stations on every major island in the area to map anisotropy in the crust, the mantle wedge and the slab/sub-slab mantle. To date this is the most comprehensive study of anisotropy in this region, involving 52 stations from 8 seismic networks. Local event delay times (0.21 ± 0.12 s) do not increase with depth, indicating a crustal origin in anisotropy and an isotropic mantle wedge. Teleseismic delay times are much larger (1.34 ± 0.47 s), with fast shear-wave polarisations that are predominantly parallel to trend of the arc. These observations can be interpreted three ways: (1) the presence of pre-existing anisotropy in the subducting slab; (2) anisotropy due to sub-slab mantle flow around the eastern margin of the nearly stationary Caribbean plate; (3) some combination of both mechanisms. However, there are two notable variations in the trench-parallel pattern of anisotropy - trench-perpendicular alignment is observed in narrow regions east of Puerto Rico and south of Martinique. These observations support previously proposed ideas of eastward sublithospheric mantle flow through gaps in the slab. Furthermore, the pattern of anisotropy south of Martinique, near Saint Lucia is consistent with a previously proposed location for the boundary between the North and South American plates.

  14. Automated seismic detection of landslides at regional scales: a Random Forest based detection algorithm

    Science.gov (United States)

    Hibert, C.; Michéa, D.; Provost, F.; Malet, J. P.; Geertsema, M.

    2017-12-01

    Detection of landslide occurrences and measurement of their dynamics properties during run-out is a high research priority but a logistical and technical challenge. Seismology has started to help in several important ways. Taking advantage of the densification of global, regional and local networks of broadband seismic stations, recent advances now permit the seismic detection and location of landslides in near-real-time. This seismic detection could potentially greatly increase the spatio-temporal resolution at which we study landslides triggering, which is critical to better understand the influence of external forcings such as rainfalls and earthquakes. However, detecting automatically seismic signals generated by landslides still represents a challenge, especially for events with small mass. The low signal-to-noise ratio classically observed for landslide-generated seismic signals and the difficulty to discriminate these signals from those generated by regional earthquakes or anthropogenic and natural noises are some of the obstacles that have to be circumvented. We present a new method for automatically constructing instrumental landslide catalogues from continuous seismic data. We developed a robust and versatile solution, which can be implemented in any context where a seismic detection of landslides or other mass movements is relevant. The method is based on a spectral detection of the seismic signals and the identification of the sources with a Random Forest machine learning algorithm. The spectral detection allows detecting signals with low signal-to-noise ratio, while the Random Forest algorithm achieve a high rate of positive identification of the seismic signals generated by landslides and other seismic sources. The processing chain is implemented to work in a High Performance Computers centre which permits to explore years of continuous seismic data rapidly. We present here the preliminary results of the application of this processing chain for years

  15. Heterogeneous Structure and Seismicity beneath the Tokyo Metropolitan Area

    Science.gov (United States)

    Nakagawa, S.; Kato, A.; Sakai, S.; Nanjo, K.; Panayotopoulos, Y.; Kurashimo, E.; Obara, K.; Kasahara, K.; Aketagawa, T.; Kimura, H.; Hirata, N.

    2010-12-01

    Beneath the Tokyo metropolitan area, the Philippine Sea Plate (PSP) subducts and causes damaged mega-thrust earthquakes. Sato et al. (2005) revealed the geometry of upper surface of PSP, and Hagiwara et al. (2006) estimated the velocity structure beneath Boso peninsula. However, these results are not sufficient for the assessment of the entire picture of the seismic hazards beneath the Tokyo metropolitan area including those due to an intra-slab M7+ earthquake. So, we launched the Special Project for Earthquake Disaster Mitigation in the Tokyo Metropolitan area (Hirata et al., 2009). Proving the more detailed geometry and physical properties (e.g. velocities, densities, attenuation) and stress field within PSP is very important to attain this issue. The core item of this project is a dense seismic array called Metropolitan Seismic Observation network (MeSO-net) for making observations in the metropolitan area (Sakai and Hirata, 2009; Kasahara et al., 2009). We deployed the 249 seismic stations with a spacing of 5 km. Some parts of stations construct 5 linear arrays at interval of 2 km such as Tsukuba-Fujisawa (TF) array, etc. The TF array runs from northeast to southwest through the center of Tokyo. In this study, we applied the tomography method to image the heterogeneous structure under the Tokyo metropolitan area. We selected events from the Japan Meteorological Agency (JMA) unified earthquake list. All data of MeSO-net were edited into event data by the selected JMA unified earthquake list. We picked the P and S wave arrival times. The total number of stations and events are 421 and 1,256, respectively. Then, we applied the double-difference tomography method (Zhang and Thurber, 2003) to this dataset and estimated the fine-scale velocity structure. The grid nodes locate 10 km interval in parallel with the array, 20 km interval in perpendicular to the array; and on depth direction, 5 km interval to a depth of less than 50 km and 10 km interval at a depth of more

  16. Seismic-resistant design of nuclear power stations in Japan, earthquake country. Lessons learned from Chuetsu-oki earthquake

    International Nuclear Information System (INIS)

    Irikura, Kojiro

    2008-01-01

    The new assessment (back-check) of earthquake-proof safety was being conducted at Kashiwazaki-Kariwa Nuclear Power Plants, Tokyo Electric Co. in response to a request based on the guideline for reactor evaluation for seismic-resistant design code, revised in 2006, when the 2007 Chuetsu-oki Earthquake occurred and brought about an unexpectedly huge tremor in this area, although the magnitude of the earthquake was only 6.8 but the intensity of earthquake motion exceeded 2.5-fold more than supposed. This paper introduces how and why the guideline for seismic-resistant design of nuclear facilities was revised in 2006, the outline of the Chuetsu-oki Earthquake, and preliminary findings and lessons learned from the Earthquake. The paper specifically discusses on (1) how we may specify in advance geologic active faults as has been overlooked this time, (2) how we can make adequate models for seismic origin from which we can extract its characteristics, and (3) how the estimation of strong ground motion simulation may be possible for ground vibration level of a possibly overlooked fault. (S. Ohno)

  17. LLNL's Regional Seismic Discrimination Research

    International Nuclear Information System (INIS)

    Hanley, W; Mayeda, K; Myers, S; Pasyanos, M; Rodgers, A; Sicherman, A; Walter, W

    1999-01-01

    As part of the Department of Energy's research and development effort to improve the monitoring capability of the planned Comprehensive Nuclear-Test-Ban Treaty international monitoring system, Lawrence Livermore Laboratory (LLNL) is testing and calibrating regional seismic discrimination algorithms in the Middle East, North Africa and Western Former Soviet Union. The calibration process consists of a number of steps: (1) populating the database with independently identified regional events; (2) developing regional boundaries and pre-identifying severe regional phase blockage zones; (3) measuring and calibrating coda based magnitude scales; (4a) measuring regional amplitudes and making magnitude and distance amplitude corrections (MDAC); (4b) applying the DOE modified kriging methodology to MDAC results using the regionalized background model; (5) determining the thresholds of detectability of regional phases as a function of phase type and frequency; (6) evaluating regional phase discriminant performance both singly and in combination; (7) combining steps 1-6 to create a calibrated discrimination surface for each stations; (8) assessing progress and iterating. We have now developed this calibration procedure to the point where it is fairly straightforward to apply earthquake-explosion discrimination in regions with ample empirical data. Several of the steps outlined above are discussed in greater detail in other DOE papers in this volume or in recent publications. Here we emphasize the results of the above process: station correction surfaces and their improvement to discrimination results compared with simpler calibration methods. Some of the outstanding discrimination research issues involve cases in which there is little or no empirical data. For example in many cases there is no regional nuclear explosion data at IMS stations or nearby surrogates. We have taken two approaches to this problem, first finding and using mining explosion data when available, and

  18. Study on structural seismic margin and probabilistic seismic risk. Development of a structural capacity-seismic risk diagram

    International Nuclear Information System (INIS)

    Nakajima, Masato; Ohtori, Yasuki; Hirata, Kazuta

    2010-01-01

    Seismic margin is extremely important index and information when we evaluate and account seismic safety of critical structures, systems and components quantitatively. Therefore, it is required that electric power companies evaluate the seismic margin of each plant in back-check of nuclear power plants in Japan. The seismic margin of structures is usually defined as a structural capacity margin corresponding to design earthquake ground motion. However, there is little agreement as to the definition of the seismic margin and we have no knowledge about a relationship between the seismic margin and seismic risk (annual failure probability) which is obtained in PSA (Probabilistic Safety Assessment). The purpose of this report is to discuss a definition of structural seismic margin and to develop a diagram which can identify a relation between seismic margin and seismic risk. The main results of this paper are described as follows: (1) We develop seismic margin which is defined based on the fact that intensity of earthquake ground motion is more appropriate than the conventional definition (i.e., the response-based seismic margin) for the following reasons: -seismic margin based on earthquake ground motion is invariant where different typed structures are considered, -stakeholders can understand the seismic margin based on the earthquake ground motion better than the response-based one. (2) The developed seismic margin-risk diagram facilitates us to judge easily whether we need to perform detailed probabilistic risk analysis or only deterministic analysis, given that the reference risk level although information on the uncertainty parameter beta is not obtained. (3) We have performed numerical simulations based on the developed method for four sites in Japan. The structural capacity-risk diagram differs depending on each location because the diagram is greatly influenced by seismic hazard information for a target site. Furthermore, the required structural capacity

  19. Seismic monitoring at the Decatur, Ill., CO2 sequestration demonstration site

    Science.gov (United States)

    Kaven, Joern; Hickman, Stephen H.; McGarr, Arthur F.; Walter, Steve R.; Ellsworth, William L.

    2014-01-01

    The viability of carbon capture and storage (CCS) to reduce emissions of greenhouse gases depends on the ability to safely sequester large quantities of CO2 over geologic time scales. One concern with CCS is the potential of induced seismicity. We report on ongoing seismic monitoring by the U.S. Geological Survey (USGS) at a CCS demonstration site in Decatur, IL, in an effort to understand the potential hazards posed by injection-induced seismicity associated with geologic CO2 sequestration. At Decatur, super-critical CO2 is injected at 2.1 km depth into the 550-m-thick Mt. Simon Sandstone, which directly overlies granitic basement. The primary sealing cap rock is the Eau Claire Shale, a 100- to 150-m-thick unit at a depth of roughly 1.5 km. The USGS seismic network consists of 12 stations, three of which have surface accelerometers and three-component borehole geophones. We derived a one-dimensional velocity models from a vertical seismic profile acquired by Archer-Daniels-Midland (ADM) and the Illinois State Geological Survey (ISGS) to a depth of 2.2 km, tied into shallow acoustic logs from our borehole stations and assuming a 6 km/sec P-wave velocity for granite below 2.2 km. We further assume a constant ratio of P- to S-wave velocities of 1.83, as derived from velocity model inversions. We use this velocity model to locate seismic events, all of which are within the footprint of our network. So far magnitudes of locatable events range from Mw = -1.52 to 1.07. We further improved the hypocentral precision of microseismic events when travel times and waveforms are sufficiently similar by employing double-difference relocation techniques, with relative location errors less than 80 m horizontally and 100 m vertically. We observe tend to group in three distinct clusters: ∼0.4 to 1.0 km NE, 1.6 to 2.4 km N, and ∼1.8 to 2.6 km WNW from the injection well. The first cluster of microseismicity forms a roughly linear trend, which may represent a pre-existing geologic

  20. A Study on distinguishing seismic waves caused by natural earthquakes and underground nuclear explosion within North Korean Context

    Science.gov (United States)

    Premlet, B.; Sabu, S.; Kamarudheen, R.; Subair, S.

    2017-12-01

    Since the first nuclear test on 15 July 1945 , there have been over 2,051 other weapon tests around the world . The waveforms of a natural earthquake which generates strong S waves and an underground explosion which is dominated by P waves were distinguished from the analysis of data corresponding to a 2005 M5.0 Earthquake and a 2016 North Korean nuclear test , both at similar distances from seismometer . Further differences between the seismograms were evaluated and successfully distinguished between the origins of the elastic waves through the data using Moment Tensor Solution using stations BJT , HIA and INCN . North Korea has developed a nuclear fuel cycle capability and has both plutonium and enriched uranium programs at Pyongyang . Seismic recordings of vertical ground motion at Global Seismographic Network station IC.MDJ of the 4 seismic events at Punggye-ri , North Korea , which occurred on the 9th of October 2006 , 25th of May 2009, 12th of February 2013 and on the 6th of January and 9th of September , 2016 were examined and the P waves of these seismic waves , which show very similar wave form , were inspected and compared to the seismic data of the latest underground nuclear test on the 3rd of September 2017 at 03:30 UTC at the same site which is many times more powerful than the previous tests . The country , which is the only nation to have tested nuclear weapons in this millennium , has successfully prevented the release of radioactive isotopes and hampered data collection but further studies were done using acoustic data which was analysed from sonograms of the 4 North Korean tests at station MDJ. The latest explosion data from 3rd September was also compared to 42 presumed underground explosions which occurred in China , India , the U.S.S.R , Iran , Turkey and recorded at Arkansas Seismic Network.

  1. Directivity of seismic radiation from a series of line charges

    Energy Technology Data Exchange (ETDEWEB)

    Ahrens, Thomas J [Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)

    1970-05-15

    A series of two-dimensional calculations describing the stress wave propagation from a row of line explosive sources, detonated sequentially at a supersonic phase velocity on the surface of various layered (half-space) crustal models, was carried out. Spectral ratios of the resulting free-surface velocities at a series of hypothetical seismic stations were used to calculate directivity functions. As in the case considered earlier by Ben-Menahem (where the source moved subsonically), strong enhancement of certain frequencies in the spectrum of the horizontal component of velocity was obtained. Directivity is especially prominent when the explosion-induced signals are generated in a medium in which the longitudinal elastic wave velocity is comparable to the detonation phase velocity and when the seismic signal being analyzed has been refracted from a higher-velocity, underlying layer. (author)

  2. On measuring surface wave phase velocity from station–station cross-correlation of ambient signal

    DEFF Research Database (Denmark)

    Boschi, Lapo; Weemstra, Cornelis; Verbeke, Julie

    2012-01-01

    We apply two different algorithms to measure surface wave phase velocity, as a function of frequency, from seismic ambient noise recorded at pairs of stations from a large European network. The two methods are based on consistent theoretical formulations, but differ in the implementation: one met...

  3. Signal Processing for Indian and Pakistan Nuclear Tests Recorded at IMS Stations Located in Israel

    Science.gov (United States)

    Gitterman, Y.; Pinsky, V.; Hofstetter, R.

    - In compliance with the Comprehensive Nuclear-Test-Ban-Treaty (CTBT) the International Monitoring System (IMS) was designed for detection and location of the clandestine Nuclear Tests (NT). Two auxiliary IMS seismic stations MRNI and EIL, deployed recently, were subjected to detectability, travel-time calibration and discrimination analysis. The study is based on the three recent 1998 underground nuclear explosions: one of India and two of Pakistan, which provided a ground-truth test of the existing IMS. These events, attaining magnitudes of 5.2, 4.8 and 4.6 correspondingly, were registered by many IMS and other seismic stations.The MRNI and EIL broadband (BB) stations are located in Israel at teleseismic distances (from the explosions) of 3600, 2800 and 2700km, respectively, where the signals from the tests are already weak. The Indian and the second Pakistan NT were not detected by the short-period Israel Seismic Network (ISN), using standard STA/LTA triggering. Therefore, for the chosen IMS stations we compare the STA/LTA response to the results of the more sensitive Murdock-Hutt (MH) and the Adaptive Statistically Optimal Detector (OD) that showed triggering for these three events. The second Pakistan NT signal arrived at the ISN and the IMS stations in the coda of a strong Afghanistan earthquake and was further disturbed by a preceding signal from a local earthquake. However, the NT signal was successfully extracted at EIL and MRNI stations using MH and OD procedures. For comparison we provide the signal analysis of the cooperating BB station JER, with considerably worse noise conditions than EIL and MRNI, and show that OD can detect events when the other algorithms fail. Using the most quiet EIL station, the most sensitive OD and different bandpass filters we tried in addition to detect the small Kazakh chemical 100-ton calibration explosion of 1998, with magnitude 3.7 at a distance approaching 4000km. The detector response curve showed uprising in the

  4. The LVD signals during the early-mid stages of the L'Aquila seismic sequence and the radon signature of some aftershocks of moderate magnitude

    International Nuclear Information System (INIS)

    Cigolini, C.; Laiolo, M.; Coppola, D.

    2015-01-01

    The L'Aquila seismic swarm culminated with the mainshock of April 6, 2009 (M L = 5.9). Here, we report and analyze the Large Volume Detector (LVD, used in neutrinos research) low energy traces (∼0.8 MeV), collected during the early-mid stages of the seismic sequence, together with the data of a radon monitoring experiment. The peaks of LVD traces do not correlate with the evolution and magnitude of earthquakes, including major aftershocks. Conversely, our radon measurements obtained by utilizing three automatic stations deployed along the regional NW–SE faulting system, seem to be, in one case, more efficient. In fact, the timeseries collected on the NW–SE Paganica fracture recorded marked variations and peaks that occurred during and prior moderate aftershocks (with M L > 3). The Paganica monitoring station (PGN) seems to better responds to active seismicity due to the fact that the radon detector was placed directly within the bedrock of an active fault. It is suggested that future networks for radon monitoring of active seismicity should preferentially implement this setting. - Highlights: • The April 9, 2009 Aquila earthquake (ML 5.9) had a remarkable echo in the media. • We report LVD traces together with the data of a radon monitoring experiment. • Radon emissions were measured by 3 automatic stations along the main NW–SE fault. • The one that better responds to seismicity was placed in the fault's bedrock. • Future networks for earthquake radon monitoring should implement this setting

  5. Seismic Structure of Mantle Transition Zone beneath Northwest Pacific Subduction Zone and its Dynamic Implication

    Science.gov (United States)

    Li, J.; Guo, G.; WANG, X.; Chen, Q.

    2017-12-01

    The northwest Pacific subduction region is an ideal location to study the interaction between the subducting slab and upper mantle discontinuities. Various and complex geometry of the Pacific subducting slab can be well traced downward from the Kuril, Japan and Izu-Bonin trench using seismicity and tomography images (Fukao and Obayashi, 2013). Due to the sparse distribution of seismic stations in the sea, investigation of the deep mantle structure beneath the broad sea regions is very limited. In this study, we applied the well- developed multiple-ScS reverberations method (Wang et al., 2017) to analyze waveforms recorded by the Chinese Regional Seismic Network, the densely distributed temporary seismic array stations installed in east Asia. A map of the topography of the upper mantle discontinuities beneath the broad oceanic regions in northwest Pacific subduction zone is imaged. We also applied the receiver function analysis to waveforms recorded by stations in northeast China and obtain the detailed topography map beneath east Asia continental regions. We then combine the two kinds of topography of upper mantle discontinuities beneath oceanic and continental regions respectively, which are obtained from totally different methods. A careful image matching and spatial correlation is made in the overlapping study regions to calibrate results with different resolution. This is the first time to show systematically a complete view of the topography of the 410-km and 660-km discontinuities beneath the east Asia "Big mantle wedge" (Zhao and Ohtani, 2009) covering the broad oceanic and continental regions in the Northwestern Pacific Subduction zone. Topography pattern of the 660 and 410 is obtained and discussed. Especially we discovered a broad depression of the 410-km discontinuity covering more than 1000 km in lateral, which seems abnormal in the cold subducting tectonic environment. Based on plate tectonic reconstruction studies and HTHP mineral experiments, we

  6. Pn seismic wave travel time at the Semipalatinsk Test Site - Borovoe seismic station trace

    International Nuclear Information System (INIS)

    An, V.A.; Kaazik, P.B.; Ovchinnikov, V.M.

    2001-01-01

    This paper preparation involved 160 explosions at the Degelen Site conducted in 1961-1989 and 89 explosions at the Balapan Site conducted in 1968-1989. Pn wave travel time was tied to the sea level in accordance with velocity characteristics of the explosion hypocenter medium; and to average epicentral distance for every site basing on their local travel time curves of Pn wave relative to Borovoe station. Maximum amplitude of mean-year travel times variations is 0.3-0.5 s as at the Nevada Test Site - Borovoe trace and Mirniy (Antarctica). However, the linear trend in contrast to previous traces has negative sign (0.08 s for Degelen and 0.1 s for Balapan). Thus, Pn wave velocity increases with calendar time. (author)

  7. Determination of stability of saturated sands of Bredasdorp and Varswater Formations: Koeberg nuclear power station

    International Nuclear Information System (INIS)

    De Witt, M.J.; Barker, O.B.

    1985-01-01

    The planning of the Koeberg nuclear power station was postulated on the basis of possible seismic ground movements of sufficient intensity to cause liquefaction of the sand overlying the bedrock. Where seismic instability may occur, it is normally necessary for the potentially liquefiable soils to be removed and replaced with a stable material. The site investigations were therefore designed to evaluate the soils parameters necessary for the safe excavation of sand. The properties of potential backfill materials were studied and requirements for selective stockpiling of material from the excavation defined

  8. Seismic Interferometry of Gulf of Mexico Basin Opening (GUMBO) Data: Extraction of Body and Surface Waves with a Mixed-Mode Array

    Science.gov (United States)

    Thangraj, J. S.; Quiros, D.; Pulliam, J.

    2017-12-01

    The Gulf of Mexico (GoM) is a relative small oceanic basin that formed by rifting between the continental blocks of North America and Yucatan in the Middle to Late Jurassic. Following the breakup, seafloor spreading continued until the Early Cretaceous. Since then, subsidence and sedimentation have shaped the GoM margin that we see today. To better understand the opening of the GoM, a long-offset (307 km) seismic refraction line was acquired in 2010. The transect was located on the northwest GoM margin, and consisted of several types of instruments. This mixed-mode array combined 31 ocean bottom seismographs (OBS), 412 high-frequency instruments (4.5 Hz geophones with RefTek 125A "Texan" digitizers) and 12 broadband stations. The R/V Iron Cat provided the airgun source used in the refraction experiment. The airgun generated 2028 shots in a period of 2.5 days which were recorded by the entire array. The airgun-generated seismic energy was clearly visible on the OBS recordings, however its amplitude was too low to be discerned on most of the onshore stations. In fact, this energy was only visible on Texan stations 1-50 (station 1 is located at the coast), extending 18 km inland, limiting the extend of the velocity model that can be obtained. Here, we apply seismic interferometry techniques to the 2.5 days of continuous data recorded by the Texan array with the goal of extending the spatial range for which the airgun-generated seismic energy can be observed. Preliminary results show that by treating the 2.5 days of continuously recorded airgun data as ambient noise, and applying time-domain cross-correlation, we can observe energy propagating 50 to 70 km inland with apparent velocities of 1800 - 2200 ms-1. These velocities agree with the compressional seismic velocity for the top 5 km of sediments under the GoM obtained from the OBS records, suggesting that we are observing compressional energy in the virtual source gathers (VSG). We also observe arrivals in the VSG

  9. Earthquakes in Action: Incorporating Multimedia, Internet Resources, Large-scale Seismic Data, and 3-D Visualizations into Innovative Activities and Research Projects for Today's High School Students

    Science.gov (United States)

    Smith-Konter, B.; Jacobs, A.; Lawrence, K.; Kilb, D.

    2006-12-01

    The most effective means of communicating science to today's "high-tech" students is through the use of visually attractive and animated lessons, hands-on activities, and interactive Internet-based exercises. To address these needs, we have developed Earthquakes in Action, a summer high school enrichment course offered through the California State Summer School for Mathematics and Science (COSMOS) Program at the University of California, San Diego. The summer course consists of classroom lectures, lab experiments, and a final research project designed to foster geophysical innovations, technological inquiries, and effective scientific communication (http://topex.ucsd.edu/cosmos/earthquakes). Course content includes lessons on plate tectonics, seismic wave behavior, seismometer construction, fault characteristics, California seismicity, global seismic hazards, earthquake stress triggering, tsunami generation, and geodetic measurements of the Earth's crust. Students are introduced to these topics through lectures-made-fun using a range of multimedia, including computer animations, videos, and interactive 3-D visualizations. These lessons are further enforced through both hands-on lab experiments and computer-based exercises. Lab experiments included building hand-held seismometers, simulating the frictional behavior of faults using bricks and sandpaper, simulating tsunami generation in a mini-wave pool, and using the Internet to collect global earthquake data on a daily basis and map earthquake locations using a large classroom map. Students also use Internet resources like Google Earth and UNAVCO/EarthScope's Jules Verne Voyager Jr. interactive mapping tool to study Earth Science on a global scale. All computer-based exercises and experiments developed for Earthquakes in Action have been distributed to teachers participating in the 2006 Earthquake Education Workshop, hosted by the Visualization Center at Scripps Institution of Oceanography (http

  10. Investigation of Seismic Waves from Non-Natural Sources: A Case Study for Building Collapse and Surface Explosion

    Science.gov (United States)

    Houng, S.; Hong, T.

    2013-12-01

    The nature and excitation mechanism of incidents or non-natural events have been widely investigated using seismological techniques. With introduction of dense seismic networks, small-sized non-natural events such as building collapse and chemical explosions are well recorded. Two representative non-natural seismic sources are investigated. A 5-story building in South Korea, Sampoong department store, was collapsed in June 25, 1995, causing casualty of 1445. This accident is known to be the second deadliest non-terror-related building collapse in the world. The event was well recorded by a local station in ~ 9 km away. P and S waves were recorded weak, while monotonic Rayleigh waves were observed well. The origin time is determined using surface-wave arrival time. The magnitude of event is determined to be 1.2, which coincides with a theoretical estimate based on the mass and volume of building. Synthetic waveforms are modeled for various combinations of velocity structures and source time functions, which allow us to constrain the process of building collapse. It appears that the building was collapsed once within a couple of seconds. We also investigate a M2.1 chemical explosion at a fertilizer plant in Texas on April 18, 2013. It was reported that more than one hundred people were dead or injured by the explosion. Seismic waveforms for nearby stations are collected from Incorporated Research Institution of Seismology (IRIS). The event was well recorded at stations in ~500 km away from the source. Strong acoustic signals were observed at stations in a certain great-circle direction. This observation suggests preferential propagation of acoustic waves depending on atmospheric environment. Waveform cross-correlation, spectral analysis and waveform modeling are applied to understand the source physics. We discuss the nature of source and source excitation mechanism.

  11. Fifteen years of seismic monitoring at the Las Tres Virgenes, BCS, geothermal field; Quince anos de monitoreo sismico en el campo geotermico de Las Tres Virgenes, BCS

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz Prieto, Irais; Lorenzo Pulido, Cecilia [Comision Federal de Electricidad, Gerencia de Proyectos Geotermoelectricos, Morelia, Michoacan (Mexico)]. E-mail: cecilia.lorenzo@cfe.gob.mx

    2009-07-15

    Seismic monitoring at the Las Tres Virgenes, BCS, geothermal field started in 1992 with an analog station of vertical components detecting a large number of earthquakes of varying magnitudes. In February 1993, a seismic network was installed, composed of six digital stations DR-2000-with S-6000 and S-5000 sensors and three registration channels (N-S, E-W and vertical). This was the basis for the development of a program to correct arrival-time data for P and S waves due to instrument drift. From January to April 1994 and May to August 1995, based on the 170 seismic events recorded, a velocity model was proposed. From December 1995 to July 1996, seismic data were processed and interpreted, and zones of occurrence were determined for events according to magnitude and the predominant noise in the field. From September 2003 to December 2004, 10 seismic stations (permanent and temporary) were installed and monitored and it was concluded the most active fault system was El Volcan. From September to December 2004, production wells LV-4 and LV-13 were acid-stimulated and seismic monitoring during this period allowed for the definition of two important seismic zones, both related to the El Volcan fault system and to injection well LV-8. After reopening these production wells, it was concluded an increase in seismic activity had occurred. From May to August 2006, information was compiled from the seismic network and it was concluded El Partido had became the most active fault system. Presently the seismic network in this field is composed of one SARA station and four K2 units. The SARA station is telemetrically connected to the base station. [Spanish] En el campo geotermico de Las Tres Virgenes, BCS, el monitoreo sismico empezo a partir de 1992 con una sola estacion analogica de registro vertical, la cual detecto una gran cantidad de temblores de distintas magnitudes. En febrero de 1993 se instalo una red sismica con seis estaciones digitales DR-2000 con sensores S-6000 y S

  12. The Seismic Analyzer: Interpreting and Illustrating 2D Seismic Data

    OpenAIRE

    Patel, Daniel; Giertsen, Christopher; Thurmond, John; Gjelberg, John; Gröller, Eduard

    2008-01-01

    We present a toolbox for quickly interpreting and illustrating 2D slices of seismic volumetric reflection data. Searching for oil and gas involves creating a structural overview of seismic reflection data to identify hydrocarbon reservoirs. We improve the search of seismic structures by precalculating the horizon structures of the seismic data prior to interpretation. We improve the annotation of seismic structures by applying novel illustrative rendering algorithms tailored to seism...

  13. New Technology Changing The Face of Mobile Seismic Networks

    Science.gov (United States)

    Brisbourne, A.; Denton, P.; Seis-Uk

    SEIS-UK, a seismic equipment pool and data management facility run by a consortium of four UK universities (Leicester, Leeds, Cambridge and Royal Holloway, London) completed its second phase in 2001. To compliment the existing broadband equipment pool, which has been deployed to full capacity to date, the consortium undertook a tender evaluation process for low-power, lightweight sensors and recorders, for use on both controlled source and passive seismic experiments. The preferred option, selected by the consortium, was the Guralp CMG-6TD system, with 150 systems ordered. The CMG-6TD system is a new concept in temporary seismic equipment. A 30s- 100Hz force-feedback sensor, integral 24bit digitiser and 3-4Gbyte of solid-state memory are all housed in a single unit. Use of the most recent technologies has kept the power consumption to below 1W and the weight to 3.5Kg per unit. The concept of the disk-swap procedure for obtaining data from the field has been usurped by a fast data download technique using firewire technology. This allows for rapid station servicing, essential when 150 stations are in use, and also ensures the environmental integrity of the system by removing the requirement for a disk access port and envi- ronmentally exposed data disk. The system therefore meets the criteria for controlled source and passive seismic experiments: (1) the single unit concept and low-weight is designed for rapid deployment on short-term projects; (2) the low power consumption reduces the power-supply requirements facilitating deployment; (3) the low self-noise and bandwidth of the sensor make it applicable to passive experiments involving nat- ural sources. Further to this acquisition process, in collaboration with external groups, the SEIS- UK data management procedures have been streamlined with the integration of the Guralp GCF format data into the PASSCAL PDB software. This allows for rapid dissemination of field data and the production of archive-ready datasets

  14. Physical properties of the crust along the seismic refraction profile Vrancea'99

    International Nuclear Information System (INIS)

    Bala, A.; Raileanu, V.; Popa, M.

    2002-01-01

    The seismic refraction project VRANCEA'99 is a contribution to the German-Romanian Collaborative Research Center (CRC) 461: 'Strong Earthquakes - a Challenge for Geosciences and Civil Engineering' which was launched by the University of Karlsruhe, Germany in collaboration with various research institutes in Romania. Preparations started already in 1998, but the actual field work was carried out in May 1999. The seismic project VRANCEA'99, was jointly organized by Geophysical Institute of Karlsruhe University, GeoForschungsZentrum (GFZ) Potsdam, Germany and National Institute for Earth Physics from Bucharest, Romania. Seismic and seismological data recorded on this profile are used to compute a reliable continuous distribution of seismic velocity ( P wave ) with depth. Nine of the explosions from seismic profile Vrancea'99 were also recorded at the seismological telemetered stations from the national seismic network. These explosions were localized as seismic events using seismologic data and also some data from recording sites with 3D sensors deployed along the profile. Time - distance graphs are used to derive the continuous distribution of velocity with depth between 5 km - 45 km depth by Wiechert - Herglotz method. The crustal 2D model from obtained on the profile VRANCEA'99 was introduced as starting model in a density modeling along the refraction profile. The measured values of Bouguer anomaly along the profile were introduced in the model in order to be compared with the computed Bouguer anomaly. After several iterations, the computed Bouguer anomaly is overlapping well enough the observed Bouguer anomaly along the profile. This certify the chosen model (obtained from seismic forward and inverse modeling) using another method of geophysical modeling. Geologic and tectonic implications of the obtained density model are discussed. (authors)

  15. Nuclear power station achievement 1968-1980

    International Nuclear Information System (INIS)

    Howles, L.R.

    This report reviews and gives an analysis of the achievement of operating nuclear power stations in the Western world on three relevant bases: (1) both annual and cumulative achievement of all nuclear power stations at a particular time; (2) cumulative achievement of all nuclear power stations at the end of the first and subsequent years of their lives to show trends with age; (3) achievement based on refuelling period considerations. Nowhere in the report are any operating details ignored, omitted or eliminated in the method of analysis. Summarising the results of the reviews shows: an improvement with time from initial electricity generation on all bases; that initially, larger sizes of reactor/turbine operate less well than smaller sizes (except for PHWR's); that after an initial number of years, the largest size units operate as well as the intermediate and smaller sizes, or better in the PHWR case; that a 75 per cent cumulative load factor achievement in the middle years of a reactor/turbines life can be expected on the refuelling period considerations base; that at June 1980, 35 nuclear power stations achieved an annual load factor over 75 per cent; that the above achievement was possible despite the repercussions following the Three Mile Island 'accident' and the shutdowns in the USA for piping system seismic adequacy checks required by the Nuclear Regulatory Commission for five nuclear power stations; and that even when reactors/turbines are reaching towards the end of their design life, there is no rapid deterioration in their achievements. (author)

  16. Shear-wave polarization analysis of the seismic swarm following the July 9th 1998 Faial (Azores) earthquake

    Science.gov (United States)

    Dias, N. A.; Matias, L.; Tellez, J.; Senos, L.; Gaspar, J. L.

    2003-04-01

    The Azores Islands, located at a tectonic triple Junction, geodynamically are a highly active place. The seismicity in this region occurs mainly in the form of two types of seismic swarms with tectonic and/or volcanic origins, lasting from hours to years. In some cases the swarm follows a main stronger shock, while in others the more energetic event occurs sometime after the beginning of the swarm. In order to understand the complex phenomena of this region, a multidisciplinary approach is needed, involving geophysical, geological and geochemical studies such as the one being carried under the MASHA project (POCTI/CTA/39158/2001), On July 9th 1998 an Mw=6.2 earthquake stroked the island of Faial, in the central group of the Azores archipelago, followed by a seismic swarm still active today. We will present some preliminary results of the shear-wave polarization analysis of a selected dataset of events of this swarm. These correspond to the 112 best- constrained events, record during the first 2 weeks by the seismic network deployed on the 3 islands surrounding the area of the main shock. The objective was to analyse the behaviour of the S wave polarization and the eventual relationship with the presence of seismic anisotropy under the seismic stations, and to correlate this with the regional structure and origin of the Azores plateau. Two main tectonic features are observable on the islands, one primarily orientated SE-NW and the other crossing it roughly with the WNW-ESE direction. The polarization direction observed in the majority of the seismic stations is not stable, varying from SE-NW to WSW-ENE, and showing also the presence in same cases of shear-wave splitting, indicating the presence of anisotropy. Part of the polarization seems to be coherent with the direction of the local tectonic features, but its instability suggest a more complex seismic anisotropy than that proposed by the model EDA of Crampin. Furthermore, the dataset revealed some limitations to

  17. Improvements in seismic event locations in a deep western U.S. coal mine using tomographic velocity models and an evolutionary search algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Adam Lurka; Peter Swanson [Central Mining Institute, Katowice (Poland)

    2009-09-15

    Methods of improving seismic event locations were investigated as part of a research study aimed at reducing ground control safety hazards. Seismic event waveforms collected with a 23-station three-dimensional sensor array during longwall coal mining provide the data set used in the analyses. A spatially variable seismic velocity model is constructed using seismic event sources in a passive tomographic method. The resulting three-dimensional velocity model is used to relocate seismic event positions. An evolutionary optimization algorithm is implemented and used in both the velocity model development and in seeking improved event location solutions. Results obtained using the different velocity models are compared. The combination of the tomographic velocity model development and evolutionary search algorithm provides improvement to the event locations. 13 refs., 5 figs., 4 tabs.

  18. Seismicity and seismotectonics of the Western Lake Ontario Region -relocation of the seismic events phase III

    International Nuclear Information System (INIS)

    Mohajer, A.A.

    1995-12-01

    Earthquake hazard analysis in Canada relies mainly on recorded earthquake data. The ability to record earthquakes of a given magnitude has varied considerably over time as has the accuracy of location determinations. Recomputation of earthquake locations has been suggested as a possible means of improving the existing data base for better definition of seismic sources. In this study, the locations of more than 50 small to moderate magnitude earthquakes (M≤5), in the western Lake Ontario region, were examined. Available seismograph records in the Record Centre of the National Archives of Canada were examined for events that occurred prior to 1978. The events recorded after this date showed increasing accuracy in their location determinations due to initiation and improvements of the Eastern Canada Telemetry Network (ECTN). Data compiled from the study are based on the relocated and/or selected events with the minimum travel time residuals at the Canadian and American stations. Except for a few scattered events in the south-central part of the Lake Ontario region, microearthquakes (M<3.5) cluster along or at the intersection of prominent aeromagnetic and gravity anomalies, within the Toronto-Hamilton Seismic Zone. This is indicative of certain seismotectonic relationships in this region. The depth distribution or the better located events show that a range of 5 to 20 km is dominant and, therefore, they are not near-surface stress relief phenomena. However, details of the structural manifestation of inferred seismogenic features need further ground truthing, backed by long term seismic monitoring. (author) 66 refs., 3 tabs., 6 figs

  19. Seismic signals hard clipping overcoming

    Science.gov (United States)

    Olszowa, Paula; Sokolowski, Jakub

    2018-01-01

    In signal processing the clipping is understand as the phenomenon of limiting the signal beyond certain threshold. It is often related to overloading of a sensor. Two particular types of clipping are being recognized: soft and hard. Beyond the limiting value soft clipping reduces the signal real gain while the hard clipping stiffly sets the signal values at the limit. In both cases certain amount of signal information is lost. Obviously if one possess the model which describes the considered signal and the threshold value (which might be slightly more difficult to obtain in the soft clipping case), the attempt of restoring the signal can be made. Commonly it is assumed that the seismic signals take form of an impulse response of some specific system. This may lead to belief that the sine wave may be the most appropriate to fit in the clipping period. However, this should be tested. In this paper the possibility of overcoming the hard clipping in seismic signals originating from a geoseismic station belonging to an underground mine is considered. A set of raw signals will be hard-clipped manually and then couple different functions will be fitted and compared in terms of least squares. The results will be then analysed.

  20. Seismic Microzonation for Refinement of Seismic Load Parameters

    Energy Technology Data Exchange (ETDEWEB)

    Savich, A. I.; Bugaevskii, A. G., E-mail: office@geodyn.ru, E-mail: bugaevskiy@geodyn.ru [Center of the Office of Geodynamic Observations in the Power Sector, an affiliate of JSC “Institut Gidroproekt” (Russian Federation)

    2016-05-15

    Functional dependencies are established for the characteristics of seismic transients recorded at various points of a studied site, which are used to propose a new approach to seismic microzonation (SMZ) that enables the creation of new SMZ maps of strong seismic motion, with due regard for dynamic parameters of recorded transients during weak earthquakes.

  1. The seismic analyzer: interpreting and illustrating 2D seismic data.

    Science.gov (United States)

    Patel, Daniel; Giertsen, Christopher; Thurmond, John; Gjelberg, John; Gröller, M Eduard

    2008-01-01

    We present a toolbox for quickly interpreting and illustrating 2D slices of seismic volumetric reflection data. Searching for oil and gas involves creating a structural overview of seismic reflection data to identify hydrocarbon reservoirs. We improve the search of seismic structures by precalculating the horizon structures of the seismic data prior to interpretation. We improve the annotation of seismic structures by applying novel illustrative rendering algorithms tailored to seismic data, such as deformed texturing and line and texture transfer functions. The illustrative rendering results in multi-attribute and scale invariant visualizations where features are represented clearly in both highly zoomed in and zoomed out views. Thumbnail views in combination with interactive appearance control allows for a quick overview of the data before detailed interpretation takes place. These techniques help reduce the work of seismic illustrators and interpreters.

  2. Seismicity of the North of the Russian Plate: Relocation of Recent Earthquakese

    Science.gov (United States)

    Morozov, A. N.; Vaganova, N. V.; Asming, V. E.; Mikhailova, Ya. A.

    2018-03-01

    The hypocenters of the earthquakes recorded in the north of the Russian Plate from 1982 to 2013 are relocated. The relocation of the hypocenters is based on the common velocity section, common methodology, and the entire set of the initial data and bulletins available from the Russian and foreign seismic stations. The efficiency of the algorithm for calculating the hypocentral parameters and the velocity section is demonstrated by the example of two nonmilitary nuclear explosions in July 18, 1985 and September 6, 1988 in the northern part of the European Russia. For the first time, two earthquakes of July 19, 1982 and October 7, 2012, which have not been previously reported in the catalogs for the north of the Russian plate, are included in the seismic catalog.

  3. A seismic refraction experiment in 2000 on the Mizuho Plateau, East Antarctica (JARE-41 -Outline of observations-

    Directory of Open Access Journals (Sweden)

    Hiroki Miyamachi

    2001-03-01

    Full Text Available A seismic refraction experiment was successfully conducted along the S17-Z20 profile on the Mizuho route, in East Antarctica, in the austral summer season of 1999-2000 (JARE-41. One hundred sixty seismic stations were temporarily installed along the profile about 180km long and five large shots with dynamite of about 600kg were fired. In addition, two shots with charge sizes of 250kg and 25kg were arranged along the profile. The obtained seismic records show the clear onsets of the first arrivals in a distance range of less than 100km from each large shot. In particular, seismic waves traveling through the ice sheet and the dispersed surface waves are distinctly observed. Some later phases are also detected. The first travel time data obtained show that a P-wave velocity in the ice sheet is 3.6-3.8km/s and an apparent velocity in the rock basement just beneath the ice sheet is almost 6.2km/s. This report describes the basic outline of the experiment and the seismic data obtained.

  4. Seismicity and seismic monitoring in the Asse salt mine

    International Nuclear Information System (INIS)

    Flach, D.; Gommlich, G.; Hente, B.

    1987-01-01

    Seismicity analyses are made in order to assess the safety of candidate sites for ultimate disposal of hazardous wastes. The report in hand reviews the seismicity history of the Asse salt mine and presents recent results of a measuring campaign made in the area. The monitoring network installed at the site supplies data and information on the regional seismicity, on seismic amplitudes under ground and above ground, and on microseismic activities. (DG) [de

  5. Hydraulic fracturing and the Crooked Lake Sequences: Insights gleaned from regional seismic networks

    Science.gov (United States)

    Schultz, Ryan; Stern, Virginia; Novakovic, Mark; Atkinson, Gail; Gu, Yu Jeffrey

    2015-04-01

    Within central Alberta, Canada, a new sequence of earthquakes has been recognized as of 1 December 2013 in a region of previous seismic quiescence near Crooked Lake, ~30 km west of the town of Fox Creek. We utilize a cross-correlation detection algorithm to detect more than 160 events to the end of 2014, which is temporally distinguished into five subsequences. This observation is corroborated by the uniqueness of waveforms clustered by subsequence. The Crooked Lake Sequences have come under scrutiny due to its strong temporal correlation (>99.99%) to the timing of hydraulic fracturing operations in the Duvernay Formation. We assert that individual subsequences are related to fracturing stimulation and, despite adverse initial station geometry, double-difference techniques allow us to spatially relate each cluster back to a unique horizontal well. Overall, we find that seismicity in the Crooked Lake Sequences is consistent with first-order observations of hydraulic fracturing induced seismicity.

  6. Bedload transport from spectral analysis of seismic noise near rivers

    Science.gov (United States)

    Hsu, L.; Finnegan, N. J.; Brodsky, E. E.

    2010-12-01

    Channel change in rivers is driven by bedload sediment transport. However, the nonlinear nature of sediment transport combined with the difficulty of making direct observations in rivers at flood hinder prediction of the timing and magnitude of bedload movement. Recent studies have shown that spectral analysis of seismic noise from seismometers near rivers illustrate a correlation between the relative amplitude of high frequency (>1 Hz) seismic noise and conditions for bedload transport, presumably from the energy transferred from clast collisions with the channel. However, a previous study in the Himalayas did not contain extensive bedload transport or discharge measurements, and the correspondence of seismic noise with proxy variables such as regional hydrologic and meteorologic data was not exact. A more complete understanding of the relationship between bedload transport and seismic noise would be valuable for extending the spatial and temporal extent of bedload data. To explore the direct relationship between bedload transport and seismic noise, we examine data from several seismic stations near the Trinity River in California, where the fluvial morphodynamics and bedload rating curves have been studied extensively. We compare the relative amplitude of the ambient seismic noise with records of water discharge and sediment transport. We also examine the noise at hourly, daily, and seasonal timescales to determine other possible sources of noise. We report the influence of variables such as local river slope, adjacent geology, anthropogenic noise, and distance from the river. The results illustrate the feasibility of using existing seismic arrays to sense radiated energy from processes of bedload transport. In addition, the results can be used to design future seismic array campaigns to optimize information about bedload transport. This technique provides great spatial and temporal coverage, and can be performed where direct bedload measurements are difficult or

  7. Alcohol advertising at Boston subway stations: an assessment of exposure by race and socioeconomic status.

    Science.gov (United States)

    Gentry, Elisabeth; Poirier, Katie; Wilkinson, Tiana; Nhean, Siphannay; Nyborn, Justin; Siegel, Michael

    2011-10-01

    We investigated the frequency of alcohol ads at all 113 subway and streetcar stations in Boston and the patterns of community exposure stratified by race, socioeconomic status, and age. We assessed the extent of alcohol advertising at each station in May 2009. We measured gross impressions and gross rating points (GRPs) for the entire Greater Boston population and for Boston public school student commuters. We compared the frequency of alcohol advertising between neighborhoods with differing demographics. For the Greater Boston population, alcohol advertising at subway stations generated 109 GRPs on a typical day. For Boston public school students in grades 5 to 12, alcohol advertising at stations generated 134 GRPs. Advertising at stations in low-poverty neighborhoods generated 14.1 GRPs and at stations in high-poverty areas, 63.6 GRPs. Alcohol ads reach the equivalent of every adult in the Greater Boston region and the equivalent of every 5th- to 12th-grade public school student each day. More alcohol ads were displayed in stations in neighborhoods with high poverty rates than in stations in neighborhoods with low poverty rates.

  8. Estimating seismic moment magnitude (Mw) of tremor bursts in northern Cascadia: Implications for the “seismic efficiency” of episodic tremor and slip

    Science.gov (United States)

    Kao, Honn; Wang, Kelin; Dragert, Herb; Kao, Jason Y.; Rogers, Garry

    2010-10-01

    We develop a method to estimate the seismic moments of deep non-volcanic tremor bursts observed in northern Cascadia. For each tremor burst, the maximum amplitudes at individual stations within a time window ±5 s around the predicted arrivals of the S phase are measured and compared to the maximum S amplitudes measured from synthetic seismograms. The proposed method is thoroughly calibrated using 464 local earthquakes and the results show excellent consistency between the reported ML and the estimated Mw. We apply the method to northern Cascadia tremors and infer that most bursts have Mw˜1.0-1.7. The corresponding b value appears to be 1, consistent with that of ordinary earthquakes but over a narrower Mw range. Comparison of cumulative tremor Mw and the Mw estimated from the accompanying slow slip suggests that the “seismic efficiency” of the Episodic Tremor and Slip (ETS) is of the order of 0.1% or less.

  9. Is the Local Seismicity in Haiti Capable of Imaging the Northern Caribbean Subduction?

    Science.gov (United States)

    Corbeau, J.; Clouard, V.; Rolandone, F.; Leroy, S. D.; de Lepinay, B. M.

    2017-12-01

    The boundary between the Caribbean (CA) and North American (NAM) plates in the Hispaniola region is the western prolongation of the NAM plate subduction evolving from a frontal subduction in the Lesser Antilles to an oblique collision against the Bahamas platform in Cuba. We analyze P-waveforms arriving at 27 broadband seismic temporary stations deployed along a 200 km-long N-S transect across Haiti, during the Trans-Haiti project. We compute teleseismic receiver functions using the ETMTRF method, and determine crustal thickness and bulk composition (Vp/Vs) using the H-k stacking method. Three distinctive crustal domains are imaged. We relate these domains to crustal terranes that have been accreted along the plate boundary during the northeastwards displacement of the CA plate. We propose a N-S crustal profile across Haiti accounting for the surface geology, shallow structural history and these new seismological constraints. Local seismicity recorded by the temporary network from April 2013 to June 2014 is used to relocate the seismicity. A total of 593 events were identified with magnitudes ranging from 1.6 to 4.5. This local seismicity, predominantly shallow (accommodation of an important part of convergence in this area.

  10. New Version of SeismicHandler (SHX) based on ObsPy

    Science.gov (United States)

    Stammler, Klaus; Walther, Marcus

    2016-04-01

    The command line version of SeismicHandler (SH), a scientific analysis tool for seismic waveform data developed around 1990, has been redesigned in the recent years, based on a project funded by the Deutsche Forschungsgemeinschaft (DFG). The aim was to address new data access techniques, simplified metadata handling and a modularized software design. As a result the program was rewritten in Python in its main parts, taking advantage of simplicity of this script language and its variety of well developed software libraries, including ObsPy. SHX provides an easy access to waveforms and metadata via arclink and FDSN webservice protocols, also access to event catalogs is implemented. With single commands whole networks or stations within a certain area may be read in, the metadata are retrieved from the servers and stored in a local database. For data processing the large set of SH commands is available, as well as the SH scripting language. Via this SH language scripts or additional Python modules the command set of SHX is easily extendable. The program is open source, tested on Linux operating systems, documentation and download is found at URL "https://www.seismic-handler.org/".

  11. German seismic regulations

    International Nuclear Information System (INIS)

    Danisch, Ruediger

    2002-01-01

    Rules and regulations for seismic design in Germany cover the following: seismic design of conventional buildings; and seismic design of nuclear facilities. Safety criteria for NPPs, accident guidelines, and guidelines for PWRs as well as safety standards are cited. Safety standards concerned with NPPs seismic design include basic principles, soil analysis, design of building structures, design of mechanical and electrical components, seismic instrumentation, and measures to be undertaken after the earthquake

  12. Establishing seismic design criteria to achieve an acceptable seismic margin

    International Nuclear Information System (INIS)

    Kennedy, R.P.

    1997-01-01

    In order to develop a risk based seismic design criteria the following four issues must be addressed: (1) What target annual probability of seismic induced unacceptable performance is acceptable? (2). What minimum seismic margin is acceptable? (3) Given the decisions made under Issues 1 and 2, at what annual frequency of exceedance should the Safe Shutdown Earthquake ground motion be defined? (4) What seismic design criteria should be established to reasonably achieve the seismic margin defined under Issue 2? The first issue is purely a policy decision and is not addressed in this paper. Each of the other three issues are addressed. Issues 2 and 3 are integrally tied together so that a very large number of possible combinations of responses to these two issues can be used to achieve the target goal defined under Issue 1. Section 2 lays out a combined approach to these two issues and presents three potentially attractive combined resolutions of these two issues which reasonably achieves the target goal. The remainder of the paper discusses an approach which can be used to develop seismic design criteria aimed at achieving the desired seismic margin defined in resolution of Issue 2. Suggestions for revising existing seismic design criteria to more consistently achieve the desired seismic margin are presented

  13. Seismic capacity of a reinforced concrete frame structure without seismic detailing and limited ductility seismic design in moderate seismicity

    International Nuclear Information System (INIS)

    Kim, J. K.; Kim, I. H.

    1999-01-01

    A four-story reinforced concrete frame building model is designed for the gravity loads only. Static nonlinear pushover analyses are performed in two orthogonal horizontal directions. The overall capacity curves are converted into ADRS spectra and compared with demand spectra. At several points the deformed shape, moment and shear distribution are calculated. Based on these results limited ductility seismic design concept is proposed as an alternative seismic design approach in moderate seismicity resign

  14. Final Scientific Report, Integrated Seismic Event Detection and Location by Advanced Array Processing

    Energy Technology Data Exchange (ETDEWEB)

    Kvaerna, T.; Gibbons. S.J.; Ringdal, F; Harris, D.B.

    2007-01-30

    In the field of nuclear explosion monitoring, it has become a priority to detect, locate, and identify seismic events down to increasingly small magnitudes. The consideration of smaller seismic events has implications for a reliable monitoring regime. Firstly, the number of events to be considered increases greatly; an exponential increase in naturally occurring seismicity is compounded by large numbers of seismic signals generated by human activity. Secondly, the signals from smaller events become more difficult to detect above the background noise and estimates of parameters required for locating the events may be subject to greater errors. Thirdly, events are likely to be observed by a far smaller number of seismic stations, and the reliability of event detection and location using a very limited set of observations needs to be quantified. For many key seismic stations, detection lists may be dominated by signals from routine industrial explosions which should be ascribed, automatically and with a high level of confidence, to known sources. This means that expensive analyst time is not spent locating routine events from repeating seismic sources and that events from unknown sources, which could be of concern in an explosion monitoring context, are more easily identified and can be examined with due care. We have obtained extensive lists of confirmed seismic events from mining and other artificial sources which have provided an excellent opportunity to assess the quality of existing fully-automatic event bulletins and to guide the development of new techniques for online seismic processing. Comparing the times and locations of confirmed events from sources in Fennoscandia and NW Russia with the corresponding time and location estimates reported in existing automatic bulletins has revealed substantial mislocation errors which preclude a confident association of detected signals with known industrial sources. The causes of the errors are well understood and are

  15. Final Scientific Report, Integrated Seismic Event Detection and Location by Advanced Array Processing

    International Nuclear Information System (INIS)

    Kvaerna, T.; Gibbons. S.J.; Ringdal, F; Harris, D.B.

    2007-01-01

    In the field of nuclear explosion monitoring, it has become a priority to detect, locate, and identify seismic events down to increasingly small magnitudes. The consideration of smaller seismic events has implications for a reliable monitoring regime. Firstly, the number of events to be considered increases greatly; an exponential increase in naturally occurring seismicity is compounded by large numbers of seismic signals generated by human activity. Secondly, the signals from smaller events become more difficult to detect above the background noise and estimates of parameters required for locating the events may be subject to greater errors. Thirdly, events are likely to be observed by a far smaller number of seismic stations, and the reliability of event detection and location using a very limited set of observations needs to be quantified. For many key seismic stations, detection lists may be dominated by signals from routine industrial explosions which should be ascribed, automatically and with a high level of confidence, to known sources. This means that expensive analyst time is not spent locating routine events from repeating seismic sources and that events from unknown sources, which could be of concern in an explosion monitoring context, are more easily identified and can be examined with due care. We have obtained extensive lists of confirmed seismic events from mining and other artificial sources which have provided an excellent opportunity to assess the quality of existing fully-automatic event bulletins and to guide the development of new techniques for online seismic processing. Comparing the times and locations of confirmed events from sources in Fennoscandia and NW Russia with the corresponding time and location estimates reported in existing automatic bulletins has revealed substantial mislocation errors which preclude a confident association of detected signals with known industrial sources. The causes of the errors are well understood and are

  16. Shallow velocity model in the area of Pozzo Pitarrone, Mt. Etna, from single station, array methods and borehole data.

    OpenAIRE

    Zuccarello, L.; Paratore, M.; Ferrari, F.; Messina, A.; Branca, S.; Contrafatto, D.; Galluzzo, D.; Rapisarda, S.; La Rocca, M.

    2016-01-01

    Seismic noise recorded by a temporary array installed around Pozzo Pitarrone, NE flank of Mt. Etna, have been analysed with several techniques. Single station HVSR method and SPAC array method have been applied to stationary seismic noise to investigate the local shallow structure. The inversion of dispersion curves produced a shear wave velocity model of the area reliable down to depth of about 130 m. A comparison of such model with the stratigraphic information available for the investigate...

  17. Locating seismicity on the Arctic plate boundary using multiple-event techniques and empirical signal processing

    Science.gov (United States)

    Gibbons, S. J.; Harris, D. B.; Dahl-Jensen, T.; Kværna, T.; Larsen, T. B.; Paulsen, B.; Voss, P. H.

    2017-12-01

    The oceanic boundary separating the Eurasian and North American plates between 70° and 84° north hosts large earthquakes which are well recorded teleseismically, and many more seismic events at far lower magnitudes that are well recorded only at regional distances. Existing seismic bulletins have considerable spread and bias resulting from limited station coverage and deficiencies in the velocity models applied. This is particularly acute for the lower magnitude events which may only be constrained by a small number of Pn and Sn arrivals. Over the past two decades there has been a significant improvement in the seismic network in the Arctic: a difficult region to instrument due to the harsh climate, a sparsity of accessible sites (particularly at significant distances from the sea), and the expense and difficult logistics of deploying and maintaining stations. New deployments and upgrades to stations on Greenland, Svalbard, Jan Mayen, Hopen, and Bjørnøya have resulted in a sparse but stable regional seismic network which results in events down to magnitudes below 3 generating high-quality Pn and Sn signals on multiple stations. A catalogue of several hundred events in the region since 1998 has been generated using many new phase readings on stations on both sides of the spreading ridge in addition to teleseismic P phases. A Bayesian multiple event relocation has resulted in a significant reduction in the spread of hypocentre estimates for both large and small events. Whereas single event location algorithms minimize vectors of time residuals on an event-by-event basis, the Bayesloc program finds a joint probability distribution of origins, hypocentres, and corrections to traveltime predictions for large numbers of events. The solutions obtained favour those event hypotheses resulting in time residuals which are most consistent over a given source region. The relocations have been performed with different 1-D velocity models applicable to the Arctic region and

  18. Awareness and understanding of earthquake hazards at school

    Science.gov (United States)

    Saraò, Angela; Peruzza, Laura; Barnaba, Carla; Bragato, Pier Luigi

    2014-05-01

    Schools have a fundamental role in broadening the understanding of natural hazard and risks and in building the awareness in the community. Recent earthquakes in Italy and worldwide, have clearly demonstrated that the poor perception of seismic hazards diminishes the effectiveness of mitigation countermeasures. Since years the Seismology's department of OGS is involved in education projects and public activities to raise awareness about earthquakes. Working together with teachers we aim at developing age-appropriate curricula to improve the student's knowledge about earthquakes, seismic safety, and seismic risk reduction. Some examples of education activities we performed during the last years are here presented. We show our experience with the primary and intermediate schools where, through hands-on activities, we explain the earthquake phenomenon and its effects to kids, but we illustrate also some teaching interventions for high school students. During the past years we lectured classes, we led laboratory and field activities, and we organized summer stages for selected students. In the current year we are leading a project aimed at training high school students on seismic safety through a multidisciplinary approach that involves seismologists, engineers and experts of safety procedures. To combine the objective of dissemination of earthquake culture, also through the knowledge of the past seismicity, with that of a safety culture, we use innovative educational techniques and multimedia resources. Students and teachers, under the guidance of an expert seismologist, organize a combination of hands-on activities for understanding earthquakes in the lab through cheap tools and instrumentations At selected schools we provided the low cost seismometers of the QuakeCatcher network (http://qcn.stanford.edu) for recording earthquakes, and we trained teachers to use such instruments in the lab and to analyze recorded data. Within the same project we are going to train

  19. Refinements to the method of epicentral location based on surface waves from ambient seismic noise: introducing Love waves

    Science.gov (United States)

    Levshin, Anatoli L.; Barmin, Mikhail P.; Moschetti, Morgan P.; Mendoza, Carlos; Ritzwoller, Michael H.

    2012-01-01

    The purpose of this study is to develop and test a modification to a previous method of regional seismic event location based on Empirical Green’s Functions (EGFs) produced from ambient seismic noise. Elastic EGFs between pairs of seismic stations are determined by cross-correlating long ambient noise time-series recorded at the two stations. The EGFs principally contain Rayleigh- and Love-wave energy on the vertical and transverse components, respectively, and we utilize these signals between about 5 and 12 s period. The previous method, based exclusively on Rayleigh waves, may yield biased epicentral locations for certain event types with hypocentral depths between 2 and 5 km. Here we present theoretical arguments that show how Love waves can be introduced to reduce or potentially eliminate the bias. We also present applications of Rayleigh- and Love-wave EGFs to locate 10 reference events in the western United States. The separate Rayleigh and Love epicentral locations and the joint locations using a combination of the two waves agree to within 1 km distance, on average, but confidence ellipses are smallest when both types of waves are used.

  20. Comprehensive seismic monitoring of the Cascadia megathrust with real-time GPS

    Science.gov (United States)

    Melbourne, T. I.; Szeliga, W. M.; Santillan, V. M.; Scrivner, C. W.; Webb, F.

    2013-12-01

    We have developed a comprehensive real-time GPS-based seismic monitoring system for the Cascadia subduction zone based on 1- and 5-second point position estimates computed within the ITRF08 reference frame. A Kalman filter stream editor that uses a geometry-free combination of phase and range observables to speed convergence while also producing independent estimation of carrier phase biases and ionosphere delay pre-cleans raw satellite measurements. These are then analyzed with GIPSY-OASIS using satellite clock and orbit corrections streamed continuously from the International GNSS Service (IGS) and the German Aerospace Center (DLR). The resulting RMS position scatter is less than 3 cm, and typical latencies are under 2 seconds. Currently 31 coastal Washington, Oregon, and northern California stations from the combined PANGA and PBO networks are analyzed. We are now ramping up to include all of the remaining 400+ stations currently operating throughout the Cascadia subduction zone, all of which are high-rate and telemetered in real-time to CWU. These receivers span the M9 megathrust, M7 crustal faults beneath population centers, several active Cascades volcanoes, and a host of other hazard sources. To use the point position streams for seismic monitoring, we have developed an inter-process client communication package that captures, buffers and re-broadcasts real-time positions and covariances to a variety of seismic estimation routines running on distributed hardware. An aggregator ingests, re-streams and can rebroadcast up to 24 hours of point-positions and resultant seismic estimates derived from the point positions to application clients distributed across web. A suite of seismic monitoring applications has also been written, which includes position time series analysis, instantaneous displacement vectors, and peak ground displacement contouring and mapping. We have also implemented a continuous estimation of finite-fault slip along the Cascadia megathrust