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Sample records for events ipeee seismic

  1. Preliminary perspectives gaines from individual plant examination of external events (IPEEE) seismic and fire submittal review

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.T.; Connell, E.; Chokshi, N. [NRC, Washington, DC (United States)] [and others

    1997-02-01

    As a result of the U.S. Nuclear Regulatory Commission (USNRC) initiated Individual plant Examination of External Events (IPEEE) program, every operating nuclear power reactor in the United States has performed an assessment of severe accident due to external events. This paper provides a summary of the preliminary insights gained through the review of 24 IPEEE submittals.

  2. An update of preliminary perspectives gained from Individual Plant Examination of External Events (IPEEE) submittal reviews

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, A.M.; Chen, J.T.; Chokshi, N. [Nuclear Regulatory Commission, Washington, DC (United States); Nowlen, S.P.; Bohn, M.P. [Sandia National Labs., Albuquerque, NM (United States); Sewell, R.; Kazarians, M.; Lambright, J. [Energy Research, Inc., Rockville, MD (United States)

    1998-03-01

    As a result of the US Nuclear Regulatory Commission (USNRC) initiated Individual Plant Examination of External Events (IPEEE) program, virtually every operating commercial nuclear power reactor in the US has performed an assessment of severe accident risk due to external events. To date, the USNRC staff has received 63 IPEEE submittals and will receive an additional 11 by mid 1998. Currently, 49 IPEEE submittals are under various stages ore view. This paper is based on the information available for those 41 plants for which at least preliminary Technical Evaluation Reports have been prepared by the review teams. The goal of the review is to ascertain whether the licensee`s IPEEE process is capable of identifying external events-induced severe accident vulnerabilities and cost-effective safety improvements to either eliminate or reduce the impact of these vulnerabilities. The review does not, however, attempt to validate or verify the results of the licensee`s IPEEE. The primary objective of this paper is to provide an update on the preliminary perspectives and insights gained from the IPEEE process.

  3. Seismic event classification system

    Science.gov (United States)

    Dowla, Farid U.; Jarpe, Stephen P.; Maurer, William

    1994-01-01

    In the computer interpretation of seismic data, the critical first step is to identify the general class of an unknown event. For example, the classification might be: teleseismic, regional, local, vehicular, or noise. Self-organizing neural networks (SONNs) can be used for classifying such events. Both Kohonen and Adaptive Resonance Theory (ART) SONNs are useful for this purpose. Given the detection of a seismic event and the corresponding signal, computation is made of: the time-frequency distribution, its binary representation, and finally a shift-invariant representation, which is the magnitude of the two-dimensional Fourier transform (2-D FFT) of the binary time-frequency distribution. This pre-processed input is fed into the SONNs. These neural networks are able to group events that look similar. The ART SONN has an advantage in classifying the event because the types of cluster groups do not need to be pre-defined. The results from the SONNs together with an expert seismologist's classification are then used to derive event classification probabilities.

  4. The ISC Seismic Event Bibliography

    Science.gov (United States)

    Di Giacomo, Domenico; Storchak, Dmitry

    2015-04-01

    The International Seismological Centre (ISC) is a not-for-profit organization operating in the UK for the last 50 years and producing the ISC Bulletin - the definitive worldwide summary of seismic events, both natural and anthropogenic - starting from the beginning of 20th century. Often researchers need to gather information related to specific seismic events for various reasons. To facilitate such task, in 2012 we set up a new database linking earthquakes and other seismic events in the ISC Bulletin to bibliographic records of scientific articles (mostly peer-reviewed journals) that describe those events. Such association allows users of the ISC Event Bibliography (www.isc.ac.uk/event_bibliography/index.php) to run searches for publications via a map-based web interface and, optionally, selecting scientific publications related to either specific events or events in the area of interest. Some of the greatest earthquakes were described in several hundreds of articles published over a period of few years. The journals included in our database are not limited to seismology but bring together a variety of fields in geosciences (e.g., engineering seismology, geodesy and remote sensing, tectonophysics, monitoring research, tsunami, geology, geochemistry, hydrogeology, atmospheric sciences, etc.) making this service useful in multidisciplinary studies. Usually papers dealing with large data set are not included (e.g., papers describing a seismic catalogue). Currently the ISC Event Bibliography includes over 17,000 individual publications from about 500 titles related to over 14,000 events that occurred in last 100+ years. The bibliographic records in the Event Bibliography start in the 1950s, and it is updated as new publications become available.

  5. Global Seismic Cross-Correlation Results: Characterizing Repeating Seismic Events

    Science.gov (United States)

    Vieceli, R.; Dodge, D. A.; Walter, W. R.

    2016-12-01

    Increases in seismic instrument quality and coverage have led to increased knowledge of earthquakes, but have also revealed the complex and diverse nature of earthquake ruptures. Nonetheless, some earthquakes are sufficiently similar to each other that they produce correlated waveforms. Such repeating events have been used to investigate interplate coupling of subduction zones [e.g. Igarashi, 2010; Yu, 2013], study spatio-temporal changes in slip rate at plate boundaries [e.g. Igarashi et al., 2003], observe variations in seismic wave propagation velocities in the crust [e.g. Schaff and Beroza, 2004; Sawazaki et al., 2015], and assess inner core rotation [e.g. Yu, 2016]. The characterization of repeating events on a global scale remains a very challenging problem. An initial global seismic cross-correlation study used over 310 million waveforms from nearly 3.8 million events recorded between 1970 and 2013 to determine an initial look at global correlated seismicity [Dodge and Walter, 2015]. In this work, we analyze the spatial and temporal distribution of the most highly correlated event clusters or "multiplets" from the Dodge and Walter [2015] study. We examine how the distributions and characteristics of multiplets are effected by tectonic environment, source-station separation, and frequency band. Preliminary results suggest that the distribution of multiplets does not correspond to the tectonic environment in any obvious way, nor do they always coincide with the occurrence of large earthquakes. Future work will focus on clustering correlated pairs and working to reduce the bias introduced by non-uniform seismic station coverage and data availability. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  6. Intelligent post processing of seismic events

    Directory of Open Access Journals (Sweden)

    F. Ringdal

    1994-06-01

    Full Text Available The Intelligent Monitoring Systern (IMS currently provides for joint processing of data from six arrays located in Northern and Central Europe. From experience with analyst review of events automatically defined by the IMS, we bave realized that the quality of the automatic event locations can be significantly improved if the event intervals are reprocessed with signal processing pararneters tuned to phases from events in the given region. The tuned processing parameters are obtained from off line analysis of events located in the region of interest. The primary goal of such intelligent post processing is to provide event definitions of a quality that minimizes the need for subsequent manual analysis. The first step in this post processing is to subdivide the arca to be monitored in order to identify sites of interest. Clearly, calibration will be the easiest and potential savings in manpower are the largest for areas of high, recurring seismicity. We bave identified 8 mining sites in Fennoscandia/NW Russia and noted that 65.6% of the events of ML > 2.0 in this region can be associated with one of these sites. This result is based on 1 year and a half of data. The second step is to refine the phase arrival and azimuth estimates using frequency filters and processing parameters that are tuned to the initial event location provided by the IMS. In this study, we have analyzed a set of 52 mining explosions from the Khibiny Massif mining area in the Kola peninsula of Russia. Very accurate locations of these events bave been provided by the seismologists from the Kola Regional Seismology Centre. Using an autoregressive likelihood technique we have been able to estimate onset times to an accuracy (standard deviation of about 0.05 s for P phases and 0.15 0.20 s for S phases. Using fixed frequency bands, azimuth can be estimated to an accuracy (one standard deviation of 0.9 degrees for the ARCESS array and 3 4 degrees for the small array recently

  7. Automatic seismic event tracking using a dynamic time warping algorithm

    Science.gov (United States)

    Jin, Song; Chen, ShuangQuan; Wei, Jianxin; Li, Xiang-Yang

    2017-10-01

    For seismic data interpretation, horizon picking based on seismic events in stacked or migrated seismic sections is essential for obtaining information on subsurface structures. This conventional work is time-consuming via manual implementation. In this paper, we develop an automatic seismic event tracking method of horizon interpretation using the dynamic time warping (DTW) algorithm. The proposed method consists of two steps: calculating local time shifts between adjacent traces through a pilot trace and then event tracking. In the method, the DTW algorithm is applied to calculate time shifts between two adjacent traces, and an improved multitrace DTW strategy is proposed to improve the robustness. One synthetic seismic trace is used to demonstrate the DTW algorithm, and a synthetic seismic section is used to verify the feasibility of the proposed method handling contaminated seismic data with noise. Finally, we apply the method to a 3D physical model dataset. The result indicates that the proposed method is quantitatively feasible for seismic event automatic tracking and is reasonably stable for noisy seismic section flattening, which also has the potential to extract seismic horizon slices effectively.

  8. Non-stationary background intensity and Caribbean seismic events

    Science.gov (United States)

    Valmy, Larissa; Vaillant, Jean

    2014-05-01

    We consider seismic risk calculation based on models with non-stationary background intensity. The aim is to improve predictive strategies in the framework of seismic risk assessment from models describing at best the seismic activity in the Caribbean arc. Appropriate statistical methods are required for analyzing the volumes of data collected. The focus is on calculating earthquakes occurrences probability and analyzing spatiotemporal evolution of these probabilities. The main modeling tool is the point process theory in order to take into account past history prior to a given date. Thus, the seismic event conditional intensity is expressed by means of the background intensity and the self exciting component. This intensity can be interpreted as the expected event rate per time and / or surface unit. The most popular intensity model in seismology is the ETAS (Epidemic Type Aftershock Sequence) model introduced and then generalized by Ogata [2, 3]. We extended this model and performed a comparison of different probability density functions for the triggered event times [4]. We illustrate our model by considering the CDSA (Centre de Données Sismiques des Antilles) catalog [1] which contains more than 7000 seismic events occurred in the Lesser Antilles arc. Statistical tools for testing the background intensity stationarity and for dynamical segmentation are presented. [1] Bengoubou-Valérius M., Bazin S., Bertil D., Beauducel F. and Bosson A. (2008). CDSA: a new seismological data center for the French Lesser Antilles, Seismol. Res. Lett., 79 (1), 90-102. [2] Ogata Y. (1998). Space-time point-process models for earthquake occurrences, Annals of the Institute of Statistical Mathematics, 50 (2), 379-402. [3] Ogata, Y. (2011). Significant improvements of the space-time ETAS model for forecasting of accurate baseline seismicity, Earth, Planets and Space, 63 (3), 217-229. [4] Valmy L. and Vaillant J. (2013). Statistical models in seismology: Lesser Antilles arc case

  9. Lithospheric structure models applied for locating the Romanian seismic events

    Directory of Open Access Journals (Sweden)

    V. Oancea

    1994-06-01

    Full Text Available The paper presents our attempts made for improving the locations obtained for local seismic events, using refined lithospheric structure models. The location program (based on Geiger method supposes a known model. The program is run for some seismic sequences which occurred in different regions, on the Romanian territory, using for each of the sequences three velocity models: 1 7 layers of constant velocity of seismic waves, as an average structure of the lithosphere for the whole territory; 2 site dependent structure (below each station, based on geophysical and geological information on the crust; 3 curves deseribing the dependence of propagation velocities with depth in the lithosphere, characterizing the 7 structural units delineated on the Romanian territory. The results obtained using the different velocity models are compared. Station corrections are computed for each data set. Finally, the locations determined for some quarry blasts are compared with the real ones.

  10. Seismic Events in Australia and the Aum Shinrikyo

    Science.gov (United States)

    Hennet, C. B.; van der Vink, G. E.; Harvey, D.

    2002-05-01

    On March 20, 1995 the Aum Shinrikyo terrorist group staged a sarin gas attack in the Tokyo Subway system in Japan that killed 12 and injured 5,000 people. Following the subway attack, the U.S. Senate initiated an investigation into the activities of this previously little known yet powerful religious cult. As part of the investigation, the U.S. Senate's Permanent Subcommittee on Investigations requested the IRIS consortium to determine the nature of a seismic event that occurred in 1993 in a remote part of western Australia, where members of the Aum Shinrikyo cult had been trying to mine uranium and had carried out tests with chemical weapons. The time and location of the seismic event coincided with eyewitness accounts of a low flying, bright object and a large explosion. The analysis of seismic data suggests that the magnitude 3.6 event occurred with a force of up to 2,000 tons of high explosive equivalent, but was unlikely to be an explosive detonation. However, the observations and data could be consistent with the impact of an approximately 3 to 4 meter wide iron meteorite, an event that can be expected to occur on land about every 30 years.

  11. Regional Seismic Event Identification and Improved Locations With Small Arrays

    National Research Council Canada - National Science Library

    Baker, Glenn

    1998-01-01

    We isolated the effect of structure immediately beneath seismic stations on seismic waveforms by determining the inference of velocity discontinuities beneath a single broadband 3-component seismic...

  12. Citizen Science Seismic Stations for Monitoring Regional and Local Events

    Science.gov (United States)

    Zucca, J. J.; Myers, S.; Srikrishna, D.

    2016-12-01

    The earth has tens of thousands of seismometers installed on its surface or in boreholes that are operated by many organizations for many purposes including the study of earthquakes, volcanos, and nuclear explosions. Although global networks such as the Global Seismic Network and the International Monitoring System do an excellent job of monitoring nuclear test explosions and other seismic events, their thresholds could be lowered with the addition of more stations. In recent years there has been interest in citizen-science approaches to augment government-sponsored monitoring networks (see, for example, Stubbs and Drell, 2013). A modestly-priced seismic station that could be purchased by citizen scientists could enhance regional and local coverage of the GSN, IMS, and other networks if those stations are of high enough quality and distributed optimally. In this paper we present a minimum set of hardware and software specifications that a citizen seismograph station would need in order to add value to global networks. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

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

    Science.gov (United States)

    Li, Peng

    This dissertation presents two innovations in seismic tomography and a new discovery of induced seismic events associated with CO2 injection at an Enhanced Oil Recovery (EOR) site. The following are brief introductions of these three works. The first innovated work is adaptive ambient seismic noise tomography (AANT). Traditional ambient noise tomography methods using regular grid nodes are often ill posed because the inversion grids do not always represent the distribution of ray paths. Large grid spacing is usually used to reduce the number of inversion parameters, which may not be able to solve for small-scale velocity structure. We present a new adaptive tomography method with irregular grids that provides a few advantages over the traditional methods. First, irregular grids with different sizes and shapes can fit the ray distribution better and the traditionally ill-posed problem can become more stable owing to the different parameterizations. Second, the data in the area with dense ray sampling will be sufficiently utilized so that the model resolution can be greatly improved. Both synthetic and real data are used to test the newly developed tomography algorithm. In synthetic data tests, we compare the resolution and stability of the traditional and adaptive methods. The results show that adaptive tomography is more stable and performs better in improving the resolution in the area with dense ray sampling. For real data, we extract the ambient noise signals of the seismic data near the Garlock Fault region, obtained from the Southern California Earthquake Data Center. The resulting group velocity of Rayleigh waves is well correlated with the geological structures. High velocity anomalies are shown in the cold southern Sierra Nevada, the Tehachapi Mountains and the Western San Gabriel Mountains. The second innovated work is local earthquake tomography with full topography (LETFT). In this work, we develop a new three-dimensional local earthquake tomography

  14. Focal mechanism of seismic events with a dipolar component

    Directory of Open Access Journals (Sweden)

    R. Console

    1995-06-01

    Full Text Available In this paper we model the geometry of a seismic source as a dislocation occurring on an elemental flat fault in an arbitrary direction with respect to the fault plane. This implies the use of a fourth parameter in addition to the three usual ones describing a simple double couple mechanism. We applied the radiation pattern obtained from the theory to a computer code written for the inversion of the observation data (amplitudes and polarities of the first onsets recorded by a network of stations. It allows the determination of the fault mechanism gener- alized in the above mentioned way. The computer code was verified on synthetic data and then applied to real data recorded by the seismic network operated by the Ente Nazionale per l'Energia Elettrica (ENEL, monitoring the geothermal field of Larderello. The experimental data show that for some events the source mechanism exhibits a significant dipolar component. However, due to the high standard deviation of the amplitude data, F-test applied to the results of the analysis shows that only for two events the confidence level for the general- ized model exceeds 90%.

  15. Influence of Tidal Forces on the Triggering of Seismic Events

    Science.gov (United States)

    Varga, Péter; Grafarend, Erik

    2017-05-01

    Tidal stresses are generated in any three-dimensional body influenced by an external inhomogeneous gravity field of rotating planets or moons. In this paper, as a special case, stresses caused within the solid Earth by the body tides are discussed from viewpoint of their influence on seismic activity. The earthquake triggering effects of the Moon and Sun are usually investigated by statistical comparison of tidal variations and temporal distribution of earthquake activity, or with the use of mathematical or experimental modelling of physical processes in earthquake prone structures. In this study, the magnitude of the lunisolar stress tensor in terms of its components along the latitude of the spherical surface of the Earth as well as inside the Earth (up to the core-mantle boundary) were calculated for the PREM (Dziewonski and Anderson in Phys Earth Planet Inter 25(4):297-356, 1981). Results of calculations prove that stress increases as a function of depth reaching a value around some kPa at the depth of 900-1500 km, well below the zone of deep earthquakes. At the depth of the overwhelming part of seismic energy accumulation (around 50 km) the stresses of lunisolar origin are only (0.0-1.0)·103 Pa. Despite the fact that these values are much smaller than the earthquake stress drops (1-30 MPa) (Kanamori in Annu Rev Earth Planet Sci 22:207-237, 1994) this does not exclude the possibility of an impact of tidal forces on outbreak of seismic events. Since the tidal potential and its derivatives are coordinate dependent and the zonal, tesseral and sectorial tides have different distributions from the surface down to the CMB, the lunisolar stress cannot influence the break-out of every seismological event in the same degree. The influencing lunisolar effect of the solid earth tides on earthquake occurrences is connected first of all with stress components acting parallel to the surface of the Earth. The influence of load tides is limited to the loaded area and its

  16. The seismic signature of rockslides: a review of events in the Central Alps

    Science.gov (United States)

    Dammeier, F.; Moore, J. R.; Haslinger, F.; Loew, S.

    2010-12-01

    Seismic recordings from regional networks may be used to identify and locate rockslide events, and can provide unique information on event characteristics that could otherwise only be established by eye witnesses. Here we analyze the seismic signals from 20 large rockslide events that occurred in the Swiss and French Alps during the last twenty years. Rockslide seismic signals have a typical ‘cigar’ shape characterized by an emergent onset and slowly decaying tail. The majority of seismic energy is contained in frequencies below ~4 Hz, and near the source, the signal generally cannot be separated into different wave types. Five seismic metrics were used to quantify differences between rockslide seismograms: seismic duration, peak amplitude of the seismic velocity envelope (ePGV), average ground velocity (AGV), rise time (RT) from event onset to ePGV, and the area of the seismic velocity envelope (EA). Three seismic metrics (EA, AGV, ePGV) exhibited loglog attenuation behavior, RT exhibited semilog attenuation behavior and duration did not show any clear attenuation with distance. For comparison between events, each seismic metric was extrapolated to a common distance of 30 km; for duration the value at the nearest station was used. Event potential energy correlated well with seismic duration and ePGV, and rock/ice avalanches could be identified by unusually low ePGV. Event volume correlated with seismic duration and EA, and rock collapses could be identified by unusually low EA. Analyzing six events that occurred from the same slope with similar runout, the correlation of ePGV and event volume was better than that for all events, indicating that runout path has an important effect on ePGV. For these six events, a plot of EA versus duration showed that rockslides with more than one sub-event lie far from the fitted curve. We also attempted to match seismic waveform features to event dynamics as observed in video footage. A high amplitude signal on a horizontal

  17. Non-stationarity and internal correlations of the occurrence process of mining-induced seismic events

    Science.gov (United States)

    Olszewska, Dorota; Lasocki, Stanislaw; Leptokaropoulos, Konstantinos

    2017-06-01

    A point process, e.g., the seismic process, is potentially predictable when it is non-stationary, internally correlated or both. In this paper, an analysis of the occurrence process of mining-induced seismic events from Rudna copper mine in Poland is presented. Stationarity and internal correlation are investigated in complete seismic time series and segmentally in subseries demonstrating relatively stable seismicity rates. It is shown that the complete seismic series are non-stationary; however, most of their shorter subseries become stationary. In the stationary subseries, the distribution of interevent time is closer to the exponential distribution, which is characteristic for the Poisson process. However, in most of these subseries, the differences between the interevent time and Poisson distributions are still significant, revealing correlations among seismic events.

  18. Error Analysis in the Joint Event Location/Seismic Calibration Inverse Problem

    National Research Council Canada - National Science Library

    Rodi, William L

    2006-01-01

    This project is developing new mathematical and computational techniques for analyzing the uncertainty in seismic event locations, as induced by observational errors and errors in travel-time models...

  19. Identification of new events in Apollo 16 lunar seismic data by Hidden Markov Model-based event detection and classification

    Science.gov (United States)

    Knapmeyer-Endrun, Brigitte; Hammer, Conny

    2015-10-01

    Detection and identification of interesting events in single-station seismic data with little prior knowledge and under tight time constraints is a typical scenario in planetary seismology. The Apollo lunar seismic data, with the only confirmed events recorded on any extraterrestrial body yet, provide a valuable test case. Here we present the application of a stochastic event detector and classifier to the data of station Apollo 16. Based on a single-waveform example for each event class and some hours of background noise, the system is trained to recognize deep moonquakes, impacts, and shallow moonquakes and performs reliably over 3 years of data. The algorithm's demonstrated ability to detect rare events and flag previously undefined signal classes as new event types is of particular interest in the analysis of the first seismic recordings from a completely new environment. We are able to classify more than 50% of previously unclassified lunar events, and additionally find over 200 new events not listed in the current lunar event catalog. These events include deep moonquakes as well as impacts and could be used to update studies on temporal variations in event rate or deep moonquakes stacks used in phase picking for localization. No unambiguous new shallow moonquake was detected, but application to data of the other Apollo stations has the potential for additional new discoveries 40 years after the data were recorded. Besides, the classification system could be useful for future seismometer missions to other planets, e.g., the InSight mission to Mars.

  20. Peak Ground Velocities for Seismic Events at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    K. Coppersmith; R. Quittmeyer

    2005-02-16

    This report describes a scientific analysis to bound credible horizontal peak ground velocities (PGV) for the repository waste emplacement level at Yucca Mountain. Results are presented as a probability distribution for horizontal PGV to represent uncertainties in the analysis. The analysis also combines the bound to horizontal PGV with results of ground motion site-response modeling (BSC 2004 [DIRS 170027]) to develop a composite hazard curve for horizontal PGV at the waste emplacement level. This result provides input to an abstraction of seismic consequences (BSC 2004 [DIRS 169183]). The seismic consequence abstraction, in turn, defines the input data and computational algorithms for the seismic scenario class of the total system performance assessment (TSPA). Planning for the analysis is documented in Technical Work Plan TWP-MGR-GS-000001 (BSC 2004 [DIRS 171850]). The bound on horizontal PGV at the repository waste emplacement level developed in this analysis complements ground motions developed on the basis of PSHA results. In the PSHA, ground motion experts characterized the epistemic uncertainty and aleatory variability in their ground motion interpretations. To characterize the aleatory variability they used unbounded lognormal distributions. As a consequence of these characterizations, as seismic hazard calculations are extended to lower and lower annual frequencies of being exceeded, the ground motion level increases without bound, eventually reaching levels that are not credible (Corradini 2003 [DIRS 171191]). To provide credible seismic inputs for TSPA, in accordance with 10 Code of Federal Regulations (CFR) 63.102(j) [DIRS 156605], this complementary analysis is carried out to determine reasonable bounding values of horizontal PGV at the waste emplacement level for annual frequencies of exceedance as low as 10{sup -8}. For each realization of the TSPA seismic scenario, the results of this analysis provide a constraint on the values sampled from the

  1. High-resolution seismic event detection using local similarity for Large-N arrays.

    Science.gov (United States)

    Li, Zefeng; Peng, Zhigang; Hollis, Dan; Zhu, Lijun; McClellan, James

    2018-01-26

    We develop a novel method for seismic event detection that can be applied to large-N arrays. The method is based on a new detection function named local similarity, which quantifies the signal consistency between the examined station and its nearest neighbors. Using the 5200-station Long Beach nodal array, we demonstrate that stacked local similarity functions can be used to detect seismic events with amplitudes near or below noise levels. We apply the method to one-week continuous data around the 03/11/2011 Mw 9.1 Tohoku-Oki earthquake, to detect local and distant events. In the 5-10 Hz range, we detect various events of natural and anthropogenic origins, but without a clear increase in local seismicity during and following the surface waves of the Tohoku-Oki mainshock. In the 1-Hz low-pass-filtered range, we detect numerous events, likely representing aftershocks from the Tohoku-Oki mainshock region. This high-resolution detection technique can be applied to both ultra-dense and regular array recordings for monitoring ultra-weak micro-seismicity and detecting unusual seismic events in noisy environments.

  2. Detection of ULF geomagnetic signals associated with seismic events in Central Mexico using Discrete Wavelet Transform

    Directory of Open Access Journals (Sweden)

    O. Chavez

    2010-12-01

    Full Text Available The geomagnetic observatory of Juriquilla Mexico, located at longitude –100.45° and latitude 20.70°, and 1946 m a.s.l., has been operational since June 2004 compiling geomagnetic field measurements with a three component fluxgate magnetometer. In this paper, the results of the analysis of these measurements in relation to important seismic activity in the period of 2007 to 2009 are presented. For this purpose, we used superposed epochs of Discrete Wavelet Transform of filtered signals for the three components of the geomagnetic field during relative seismic calm, and it was compared with seismic events of magnitudes greater than Ms > 5.5, which have occurred in Mexico. The analysed epochs consisted of 18 h of observations for a dataset corresponding to 18 different earthquakes (EQs. The time series were processed for a period of 9 h prior to and 9 h after each seismic event. This data processing was compared with the same number of observations during a seismic calm. The proposed methodology proved to be an efficient tool to detect signals associated with seismic activity, especially when the seismic events occur in a distance (D from the observatory to the EQ, such that the ratio D/ρ < 1.8 where ρ is the earthquake radius preparation zone. The methodology presented herein shows important anomalies in the Ultra Low Frequency Range (ULF; 0.005–1 Hz, primarily for 0.25 to 0.5 Hz. Furthermore, the time variance (σ2 increases prior to, during and after the seismic event in relation to the coefficient D1 obtained, principally in the Bx (N-S and By (E-W geomagnetic components. Therefore, this paper proposes and develops a new methodology to extract the abnormal signals of the geomagnetic anomalies related to different stages of the EQs.

  3. Systematic detection of seismic events at Mount St. Helens with an ultra-dense array

    Science.gov (United States)

    Meng, X.; Hartog, J. R.; Schmandt, B.; Hotovec-Ellis, A. J.; Hansen, S. M.; Vidale, J. E.; Vanderplas, J.

    2016-12-01

    During the summer of 2014, an ultra-dense array of 900 geophones was deployed around the crater of Mount St. Helens and continuously operated for 15 days. This dataset provides us an unprecedented opportunity to systematically detect seismic events around an active volcano and study their underlying mechanisms. We use a waveform-based matched filter technique to detect seismic events from this dataset. Due to the large volume of continuous data ( 1 TB), we performed the detection on the GPU cluster Stampede (https://www.tacc.utexas.edu/systems/stampede). We build a suite of template events from three catalogs: 1) the standard Pacific Northwest Seismic Network (PNSN) catalog (45 events); 2) the catalog from Hansen&Schmandt (2015) obtained with a reverse-time imaging method (212 events); and 3) the catalog identified with a matched filter technique using the PNSN permanent stations (190 events). By searching for template matches in the ultra-dense array, we find 2237 events. We then calibrate precise relative magnitudes for template and detected events, using a principal component fit to measure waveform amplitude ratios. The magnitude of completeness and b-value of the detected catalog is -0.5 and 1.1, respectively. Our detected catalog shows several intensive swarms, which are likely driven by fluid pressure transients in conduits or slip transients on faults underneath the volcano. We are currently relocating the detected catalog with HypoDD and measuring the seismic velocity changes at Mount St. Helens using the coda wave interferometry of detected repeating earthquakes. The accurate temporal-spatial migration pattern of seismicity and seismic property changes should shed light on the physical processes beneath Mount St. Helens.

  4. Sources of Error and the Statistical Formulation of M S: m b Seismic Event Screening Analysis

    Science.gov (United States)

    Anderson, D. N.; Patton, H. J.; Taylor, S. R.; Bonner, J. L.; Selby, N. D.

    2014-03-01

    The Comprehensive Nuclear-Test-Ban Treaty (CTBT), a global ban on nuclear explosions, is currently in a ratification phase. Under the CTBT, an International Monitoring System (IMS) of seismic, hydroacoustic, infrasonic and radionuclide sensors is operational, and the data from the IMS is analysed by the International Data Centre (IDC). The IDC provides CTBT signatories basic seismic event parameters and a screening analysis indicating whether an event exhibits explosion characteristics (for example, shallow depth). An important component of the screening analysis is a statistical test of the null hypothesis H 0: explosion characteristics using empirical measurements of seismic energy (magnitudes). The established magnitude used for event size is the body-wave magnitude (denoted m b) computed from the initial segment of a seismic waveform. IDC screening analysis is applied to events with m b greater than 3.5. The Rayleigh wave magnitude (denoted M S) is a measure of later arriving surface wave energy. Magnitudes are measurements of seismic energy that include adjustments (physical correction model) for path and distance effects between event and station. Relative to m b, earthquakes generally have a larger M S magnitude than explosions. This article proposes a hypothesis test (screening analysis) using M S and m b that expressly accounts for physical correction model inadequacy in the standard error of the test statistic. With this hypothesis test formulation, the 2009 Democratic Peoples Republic of Korea announced nuclear weapon test fails to reject the null hypothesis H 0: explosion characteristics.

  5. Development of Simplified Probabilistic Risk Assessment Model for Seismic Initiating Event

    Energy Technology Data Exchange (ETDEWEB)

    S. Khericha; R. Buell; S. Sancaktar; M. Gonzalez; F. Ferrante

    2012-06-01

    ABSTRACT This paper discusses a simplified method to evaluate seismic risk using a methodology built on dividing the seismic intensity spectrum into multiple discrete bins. The seismic probabilistic risk assessment model uses Nuclear Regulatory Commission’s (NRC’s) full power Standardized Plant Analysis Risk (SPAR) model as the starting point for development. The seismic PRA models are integrated with their respective internal events at-power SPAR model. This is accomplished by combining the modified system fault trees from the full power SPAR model with seismic event tree logic. The peak ground acceleration is divided into five bins. The g-value for each bin is estimated using the geometric mean of lower and upper values of that particular bin and the associated frequency for each bin is estimated by taking the difference between upper and lower values of that bin. The component’s fragilities are calculated for each bin using the plant data, if available, or generic values of median peak ground acceleration and uncertainty values for the components. For human reliability analysis (HRA), the SPAR HRA (SPAR-H) method is used which requires the analysts to complete relatively straight forward worksheets that include the performance shaping factors (PSFs). The results are then used to estimate human error probabilities (HEPs) of interest. This work is expected to improve the NRC’s ability to include seismic hazards in risk assessments for operational events in support of the reactor oversight program (e.g., significance determination process).

  6. Support Vector Machine Model for Automatic Detection and Classification of Seismic Events

    Science.gov (United States)

    Barros, Vesna; Barros, Lucas

    2016-04-01

    The automated processing of multiple seismic signals to detect, localize and classify seismic events is a central tool in both natural hazards monitoring and nuclear treaty verification. However, false detections and missed detections caused by station noise and incorrect classification of arrivals are still an issue and the events are often unclassified or poorly classified. Thus, machine learning techniques can be used in automatic processing for classifying the huge database of seismic recordings and provide more confidence in the final output. Applied in the context of the International Monitoring System (IMS) - a global sensor network developed for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) - we propose a fully automatic method for seismic event detection and classification based on a supervised pattern recognition technique called the Support Vector Machine (SVM). According to Kortström et al., 2015, the advantages of using SVM are handleability of large number of features and effectiveness in high dimensional spaces. Our objective is to detect seismic events from one IMS seismic station located in an area of high seismicity and mining activity and classify them as earthquakes or quarry blasts. It is expected to create a flexible and easily adjustable SVM method that can be applied in different regions and datasets. Taken a step further, accurate results for seismic stations could lead to a modification of the model and its parameters to make it applicable to other waveform technologies used to monitor nuclear explosions such as infrasound and hydroacoustic waveforms. As an authorized user, we have direct access to all IMS data and bulletins through a secure signatory account. A set of significant seismic waveforms containing different types of events (e.g. earthquake, quarry blasts) and noise is being analysed to train the model and learn the typical pattern of the signal from these events. Moreover, comparing the performance of the support

  7. Possibility of the use of data of infrasonic monitoring for identification of the nature of seismic events

    OpenAIRE

    Lyashchuk, A.; Andrushchenko, Yu.; Gordienko, Yu.; Karyagin, E.; Kornienko, I.

    2017-01-01

    The paper considers the possibility of the use of infrasound measurements conducted in Ukraine to verify the recorded seismic events and the use of infrasound data as one of the criteria for their identification. Registration of seismic and infrasonic signals was carried out via a network of geophysical Main center of special monitoring. To register infrasound small-aperture infrasound arrays were used, allowing directional monitoring of events. The data of 909 parameters of seismic events fr...

  8. Long-period seismic events with strikingly regular temporal patterns on Katla volcano's south flank (Iceland)

    CERN Document Server

    Sgattoni, Giulia; Guðmundsson, Ólafur; Einarsson, Páll; Tryggvason, Ari; Lund, Björn; Lucchi, Federico

    2015-01-01

    Katla is a threatening volcano in Iceland, partly covered by the M\\'yrdalsj\\"okull ice cap. The volcano has a large caldera with several active geothermal areas. A peculiar cluster of long-period seismic events started on Katla's south flank in July 2011, during an unrest episode in the caldera that culminated in a glacier outburst. The seismic events were tightly clustered at shallow depth in the Gvendarfell area, 4 km south of the caldera, under a small glacier stream on the southern margin of M\\'yrdalsj\\"okull. No seismic events were known to have occurred in this area before. The most striking feature of this seismic cluster is its temporal pattern, characterized by regular intervals between repeating seismic events, modulated by a seasonal variation. Remarkable is also the stability of both the time and waveform features over a long time period, around 3.5 years. No comparable examples have been found in the literature. Both volcanic and glacial processes can produce similar waveforms and therefore have ...

  9. Long-period seismic events with strikingly regular temporal patterns on Katla volcano's south flank (Iceland)

    OpenAIRE

    Sgattoni, Giulia; Jeddi, Zeinab; Guðmundsson, Ólafur; Einarsson, Páll; Tryggvason, Ari; LUND, Björn; Lucchi, Federico

    2015-01-01

    Katla is a threatening volcano in Iceland, partly covered by the M\\'yrdalsj\\"okull ice cap. The volcano has a large caldera with several active geothermal areas. A peculiar cluster of long-period seismic events started on Katla's south flank in July 2011, during an unrest episode in the caldera that culminated in a glacier outburst. The seismic events were tightly clustered at shallow depth in the Gvendarfell area, 4 km south of the caldera, under a small glacier stream on the southern margin...

  10. Supervised machine learning on a network scale: application to seismic event classification and detection

    Science.gov (United States)

    Reynen, Andrew; Audet, Pascal

    2017-09-01

    A new method using a machine learning technique is applied to event classification and detection at seismic networks. This method is applicable to a variety of network sizes and settings. The algorithm makes use of a small catalogue of known observations across the entire network. Two attributes, the polarization and frequency content, are used as input to regression. These attributes are extracted at predicted arrival times for P and S waves using only an approximate velocity model, as attributes are calculated over large time spans. This method of waveform characterization is shown to be able to distinguish between blasts and earthquakes with 99 per cent accuracy using a network of 13 stations located in Southern California. The combination of machine learning with generalized waveform features is further applied to event detection in Oklahoma, United States. The event detection algorithm makes use of a pair of unique seismic phases to locate events, with a precision directly related to the sampling rate of the generalized waveform features. Over a week of data from 30 stations in Oklahoma, United States are used to automatically detect 25 times more events than the catalogue of the local geological survey, with a false detection rate of less than 2 per cent. This method provides a highly confident way of detecting and locating events. Furthermore, a large number of seismic events can be automatically detected with low false alarm, allowing for a larger automatic event catalogue with a high degree of trust.

  11. Monitoring changes in seismic velocity related to an ongoing rapid inflation event at Okmok volcano, Alaska

    Science.gov (United States)

    Bennington, Ninfa; Haney, Matt; De Angelis, Silvio; Thurber, Clifford; Freymueller, Jeff

    2015-01-01

    Okmok is one of the most active volcanoes in the Aleutian Arc. In an effort to improve our ability to detect precursory activity leading to eruption at Okmok, we monitor a recent, and possibly ongoing, GPS-inferred rapid inflation event at the volcano using ambient noise interferometry (ANI). Applying this method, we identify changes in seismic velocity outside of Okmok’s caldera, which are related to the hydrologic cycle. Within the caldera, we observe decreases in seismic velocity that are associated with the GPS-inferred rapid inflation event. We also determine temporal changes in waveform decorrelation and show a continual increase in decorrelation rate over the time associated with the rapid inflation event. Themagnitude of relative velocity decreases and decorrelation rate increases are comparable to previous studies at Piton de la Fournaise that associate such changes with increased production of volatiles and/ormagmatic intrusion within the magma reservoir and associated opening of fractures and/or fissures. Notably, the largest decrease in relative velocity occurs along the intrastation path passing nearest to the center of the caldera. This observation, along with equal amplitude relative velocity decreases revealed via analysis of intracaldera autocorrelations, suggests that the inflation sourcemay be located approximately within the center of the caldera and represent recharge of shallow magma storage in this location. Importantly, there is a relative absence of seismicity associated with this and previous rapid inflation events at Okmok. Thus, these ANI results are the first seismic evidence of such rapid inflation at the volcano.

  12. Hydrogeological response to tele-seismic events with underground water level precision monitoring data

    Science.gov (United States)

    Gorbunova, Ella; Vinogradov, Evgeny; Besedina, Alina; Kabychenko, Nikolay; Svintsov, Igor

    2015-04-01

    Underground water level precision monitoring has been being carried out in the IDG RAS experimental area "Mikhnevo" in step with barometric pressure measuring since February of 2008. Seismic events registration is being realized with small aperture seismic array "Mikhnevo" and STS-2 seismometer. Complex processing of original hydrological and seismic data allows to mark out hydrological responses to large earthquakes (Mw>7.5) seismic waves propagation throw aseismic region - central area of Russian Plate. GPO "Mikhnevo" is located within South part of Moscow artesian basin in the North-East part of Prioksko-Terrasny biosphere reserve out of intensive anthropogenic impact zone. Wellbore unseals index aquifer in the interval of 91-115 m. An aquifer is characterized with season level variations. Water containing rocks are presented with nonuniform fractured limestones. In IDG RAS step-by-step methodic of experimental data handling was devised. First preliminary comparison of 1 Hz frequency seismic and hydrological data is being carried out for hydrogeological response to large earthquakes (Mw>7.5) seismic waves propagation marking out. On basis of these data main types and parameters of waves registered in seismic and hydrological data are being identified and representative periods for geological medium response to tele-seismic events analysis are being selected. In the area of GPO "Mikhnevo" we traced geological response to disastrous earthquakes that took place 02/27/2011 near Central Chile Coast and 03/11/11 near Honshu Island east coast that is presented being smoothed in underground water level. Tele-seismic events differs in intensity, signal duration and post-seismic effect. Significant water level harmonic oscillations are coupled with surface and S-waves arrival, where vertical component prevails First hydrological responses were registered in the time of S-wave propagation 28 minutes after Honshu earthquake beginning and 39 minutes after Chile earthquake

  13. Shallow repeating seismic events under an alpine glacier at Mount Rainier, Washington, USA

    Science.gov (United States)

    Thelen, Weston A.; Allstadt, Kate E.; De Angelis, Silvio; Malone, Stephen D.; Moran, Seth C.; Vidale, John

    2013-01-01

    We observed several swarms of repeating low-frequency (1–5 Hz) seismic events during a 3 week period in May–June 2010, near the summit of Mount Rainier, Washington, USA, that likely were a result of stick–slip motion at the base of alpine glaciers. The dominant set of repeating events ('multiplets') featured >4000 individual events and did not exhibit daytime variations in recurrence interval or amplitude. Volcanoes and glaciers around the world are known to produce seismic signals with great variability in both frequency content and size. The low-frequency character and periodic recurrence of the Mount Rainier multiplets mimic long-period seismicity often seen at volcanoes, particularly during periods of unrest. However, their near-surface location, lack of common spectral peaks across the recording network, rapid attenuation of amplitudes with distance, and temporal correlation with weather systems all indicate that ice-related source mechanisms are the most likely explanation. We interpret the low-frequency character of these multiplets to be the result of trapping of seismic energy under glacial ice as it propagates through the highly heterogeneous and attenuating volcanic material. The Mount Rainier multiplet sequences underscore the difficulties in differentiating low-frequency signals due to glacial processes from those caused by volcanic processes on glacier-clad volcanoes.

  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. Geothermal induced seismicity: What links source mechanics and event magnitudes to faulting regime and injection rates?

    Science.gov (United States)

    Martinez-Garzon, Patricia; Kwiatek, Grzegorz; Bohnhoff, Marco; Dresen, Georg

    2017-04-01

    Improving estimates of seismic hazard associated to reservoir stimulation requires advanced understanding of the physical processes governing induced seismicity, which can be better achieved by carefully processing large datasets. To this end, we investigate source-type processes (shear/tensile/compaction) and rupture geometries with respect to the local stress field using seismicity from The Geysers (TG) and Salton Sea geothermal reservoirs, California. Analysis of 869 well-constrained full moment tensors (MW 0.8-3.5) at TG reveals significant non-double-couple (NDC) components (>25%) for 65% of the events and remarkably diversity in the faulting mechanisms. Volumetric deformation is clearly governed by injection rates with larger NDC components observed near injection wells and during high injection periods. The overall volumetric deformation from the moment tensors increases with time, possibly reflecting a reservoir pore pressure increase after several years of fluid injection with no significant production nearby. The obtained source mechanisms and fault orientations are magnitude-dependent and vary significantly between faulting regimes. Normal faulting events (MW dilatancy, and they occur on varying fault orientations. In contrast, strike-slip events dominantly reveal a double-couple source, larger magnitudes (MW > 2) and mostly occur on optimally oriented faults with respect to the local stress field. NDC components indicating closure of cracks and pore spaces in the source region are found for reverse faulting events with MW > 2.5. Our findings from TG are generally consistent with preliminary source-type results from a reduced subset of well-recorded seismicity at the Salton Sea geothermal reservoir. Combined results imply that source processes and magnitudes of geothermal-induced seismicity are strongly affected by and systematically related to the hydraulic operations and the local stress state.

  16. 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

  17. Seismic survey in southeastern Socorro Island: Background noise measurements, seismic events, and T phases

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, Raul W [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, D.F. (Mexico); Galindo, Marta [Comprehensive Nuclear-Test-Ban Treaty Organization, IMS, Vienna (Austria); Pacheco, Javier F; Iglesias, Arturo; Teran, Luis F [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, D.F. (Mexico); Barreda, Jose L; Coba, Carlos [Facultad de Ingenieria, Benemerita Universidad Autonoma de Puebla, Puebla (Mexico)

    2005-01-15

    We carried out a seismic survey and installed five portable, broadband seismometers in the southeastern corner of Socorro Island during June 1999. Power spectral densities for all five sites were relatively noisy when compared to reference curves around the world. Power spectral densities remain constant regardless of the time of day, or the day of the week. Cultural noise at the island is very small. Quiet and noisy sites were identified to determine the best location of the T phase station to be installed jointly by the Universidad Nacional Autonoma de Mexico and the Comprehensive Nuclear-Test-Ban Treaty Organization. During the survey six earthquakes were recorded at epicentral distances between 42 km and 2202 km, with magnitudes between 2.8 and 7.0. Two small earthquakes (M{sub c} = 2.8 and 3.3) occurred on the Clarion Fracture Zone. The four largest and more distant earthquakes produced T waves. One T wave from an epicenter near the coast of Guatemala had a duration of about 100 s and a frequency content between 2 and 8 Hz, with maximum amplitude at about 4.75 Hz. The Tehuacan earthquake of June 15, 1999 (M{sub w} = 7.0) produced arrivals of P {yields} T and S {yields} T waves, with energy between 2 Hz and 3.75 Hz. The earthquake occurred inland within the subducted Cocos plate at a depth of 60 km; a significant portion of the path was continental. Seismic P and S waves probably propagated upward in the subducted slab, and were converted to acoustic energy at the continental slope. Total duration of the T phase is close to 500 s and reaches its maximum amplitude about 200 s after the P {yields} T arrival. The T wave contains energy at frequencies between 2 and 10 Hz and reaches its maximum amplitude at about 2.5 Hz. T phases were also recorded from two earthquakes in Guerrero, Mexico and in the Rivera Fracture Zone. [Spanish] En junio de 1999 instalamos cinco sismometros portatiles de banda ancha en el sureste de la Isla Socorro. Se encontro que las densidades

  18. Full-waveform detection of non-impulsive seismic events based on time-reversal methods

    Science.gov (United States)

    Solano, Ericka Alinne; Hjörleifsdóttir, Vala; Liu, Qinya

    2017-12-01

    We present a full-waveform detection method for non-impulsive seismic events, based on time-reversal principles. We use the strain Green's tensor as a matched filter, correlating it with continuous observed seismograms, to detect non-impulsive seismic events. We show that this is mathematically equivalent to an adjoint method for detecting earthquakes. We define the detection function, a scalar valued function, which depends on the stacked correlations for a group of stations. Event detections are given by the times at which the amplitude of the detection function exceeds a given value relative to the noise level. The method can make use of the whole seismic waveform or any combination of time-windows with different filters. It is expected to have an advantage compared to traditional detection methods for events that do not produce energetic and impulsive P waves, for example glacial events, landslides, volcanic events and transform-fault earthquakes for events which velocity structure along the path is relatively well known. Furthermore, the method has advantages over empirical Greens functions template matching methods, as it does not depend on records from previously detected events, and therefore is not limited to events occurring in similar regions and with similar focal mechanisms as these events. The method is not specific to any particular way of calculating the synthetic seismograms, and therefore complicated structural models can be used. This is particularly beneficial for intermediate size events that are registered on regional networks, for which the effect of lateral structure on the waveforms can be significant. To demonstrate the feasibility of the method, we apply it to two different areas located along the mid-oceanic ridge system west of Mexico where non-impulsive events have been reported. The first study area is between Clipperton and Siqueiros transform faults (9°N), during the time of two earthquake swarms, occurring in March 2012 and May

  19. A volcano-seismic event spotting system for the use in rapid response systems

    Science.gov (United States)

    Hammer, Conny; Ohrnberger, Matthias

    2010-05-01

    The classification of seismic signals of volcanic origin is an important task in monitoring active volcanoes. The number and size of certain types of seismic events usually increase before periods of volcanic crisis and can be used to quantify the volcanic activity. Due to the advantage of providing consistent, objective and time-invariant results automatic classification systems are preferred. Most automatic classification systems are trained in a supervised fashion from a sufficiently large pre-classified data set. The setup of an automatic classification system thus requires the pre-existence of these training data. For a rapid volcano-response team, however, the situation is often different. In the worst case, no prior observations exist (e.g. re-awakening of a dormant volcano). More frequently, archive data exist for a particular observatory network, but no record of seismicity for a high volcanic activity level exists and new seismicity patterns occur. Usually, the networks are additionally sparse and new equipment will be installed for better surveillance during the actual crisis. For the new recording sites again no prior example data is available. Finally, due to the imminent crisis there might be no time for the time-consuming and tedious process of preparing a training data set. For all these reasons a classification system which allows a "learning-while-recording" approach would be very advantageous for use in rapid response systems. Within this study, we show a novel seismic event spotting approach in order to reduce the dependency on the existence of previously acquired data bases and classification schemes. One main goal is therefore to provide the observatory staff with a robust event classification system based on a minimum number of reference waveforms and thus allowing for a fast build-up of a volcanic signal classification scheme as early as interesting events have been identified. For implementation issues we make use of the Hidden Markov

  20. Correlation between night time VLF amplitude fluctuations and seismic events in Indian sub-continent

    Science.gov (United States)

    Ray, Suman; Chakrabarti, Sandip Kumar; Sasmal, Sudipta

    We present the results of an analysis of yearlong (2007) monitoring of night time data of the VLF signal amplitude. We use the VLF signals, transmitted from the Indian Navy station VTX (latitude 8.43(°) N, longitude 77.73(°) E) at 18.2 kHz and received at the Indian Centre for Space Physics, Kolkata (latitude 22.5(°) N, 87.5(°) E). We analyzed this data to find out the correlation between night time amplitude fluctuation and seismic events. We found, analyzing individual earthquakes (with magnitudes >5) as well as from statistical analysis (of all the events with effective magnitudes greater than 3.5), that night time fluctuation of the signal amplitude has the highest probability to be beyond the 2σ levels about three days prior to the seismic events. Recently an earthquake of magnitude 7.4 occurred at South-western Pakistan (latitude 28.9(°) N, 64(°) E). We analyze the night time VLF signals for two weeks around this earthquake day to see if there were any precursory effects of this earthquake. We find that the amplitude of the night time VLF signals anomalously fluctuated four days before this earthquake. Thus, the night time fluctuation could be considered as a precursor to enhanced seismic activities.

  1. Unusual Fluctuations of the Nighttime VLF Signal Amplitude before Seismic Events

    Science.gov (United States)

    Ray, Suman; Chakrabarti, Sandip Kumar; Sasmal, Sudipta; Mondal, Sushanta Kumar

    2012-07-01

    We present the results of an analysis of yearlong (2007) monitoring of nighttime data of the VLF signal amplitude. We use the VLF signals, transmitted from the Indian Navy station VTX (latitude 8.43° N, longitude 77.73° E) at 18.2 kHz and received at the Indian Centre for Space Physics, Kolkata (latitude 22.5° N, 87.5° E). We analyzed this data to find out the correlation between night time amplitude fluctuation and seismic events. We found, analyzing individual earthquakes (with magnitudes greater than 5) as well as from statistical analysis (of all the events with effective magnitudes greater than 3.5), that nighttime fluctuation of the signal amplitude has the highest probability to be beyond the 2σ levels about three days prior to the seismic events. Recently an earthquake of magnitude 7.4 occurred at Southwestern Pakistan (latitude 28.9° N, longitude 64° E). We analyze the nighttime VLF signals for two weeks around this earthquake day to see if there were any precursory effects of this earthquake. We find that the amplitude of the nighttime VLF signals anomalously fluctuated four days before this earthquake. Thus, the nighttime fluctuation could be considered as a precursor to enhanced seismic activities.

  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. 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

  4. Analysis of post-blasting source mechanisms of mining-induced seismic events in Rudna copper mine, Poland

    Directory of Open Access Journals (Sweden)

    Caputa Alicja

    2015-10-01

    Full Text Available The exploitation of georesources by underground mining can be responsible for seismic activity in areas considered aseismic. Since strong seismic events are connected with rockburst hazard, it is a continuous requirement to reduce seismic risk. One of the most effective methods to do so is blasting in potentially hazardous mining panels. In this way, small to moderate tremors are provoked and stress accumulation is substantially reduced. In this paper we present an analysis of post-blasting events using Full Moment Tensor (MT inversion at the Rudna mine, Poland, underground seismic network. In addition, we describe the problems we faced when analyzing seismic signals. Our studies show that focal mechanisms for events that occurred after blasts exhibit common features in the MT solution. The strong isotropic and small Double Couple (DC component of the MT, indicate that these events were provoked by detonations. On the other hand, post-blasting MT is considerably different than the MT obtained for strong mining events. We believe that seismological analysis of provoked and unprovoked events can be a very useful tool in confirming the effectiveness of blasting in seismic hazard reduction in mining areas.

  5. Characteristics of regional seismic waves from large explosive events including Korean nuclear explosions

    Science.gov (United States)

    Jo, Eunyoung; Lee, Ha-sung

    2015-04-01

    Three North Korean underground nuclear explosion (UNE) tests were conducted in 2006, 2009 and 2013. Discrimination of explosions from natural earthquakes is important in monitoring the seismic activity in the Korean Peninsula. The UNEs were well recorded by dense regional seismic networks in South Korea. The UNEs provide unique regional seismic waveforms with high signal-to-noise ratios. However, the continental crust in the Korean Peninsula changes abruptly into a transitional structure between continental and oceanic crusts across the eastern coast. The complex geological and tectonic structures around the Korean Peninsula cause significant variations in regional waveforms. Outstanding question is whether conventional discrimination techniques can be applicable for explosions including the North Korean UNEs. P/S amplitude ratios are widely used for seismic discrimination. To understand the regional shear-energy composition, we analyze the frequency contents of waveforms. The shear-energy contents for the UNEs are compared with those for natural earthquakes with comparable magnitudes. The result shows that the UNEs are successfully discriminated from earthquakes in the Korean Peninsula. We also analyze the explosive events from North Korean not UNEs to test the applicability of the discrimination technique. The result of high frequency Pn/Sn regional discrimination in the explosions show that as magnitude of event is smaller, available distance of discrimination is decreased particularly in high frequency range. The poor signal to noise ratio of Pn phase in the explosions, and inefficient propagation of Sn phase in the Western part of the peninsula frustrate Pn/Sn discriminant, while the UNEs show good performance using both discriminants because of propagation path effects in the eastern part of the peninsula.

  6. Discovering new events beyond the catalogue—application of empirical matched field processing to Salton Sea geothermal field seismicity

    Science.gov (United States)

    Wang, Jingbo; Templeton, Dennise C.; Harris, David B.

    2015-10-01

    Using empirical matched field processing (MFP), we compare 4 yr of continuous seismic data to a set of 195 master templates from within an active geothermal field and identify over 140 per cent more events than were identified using traditional detection and location techniques alone. In managed underground reservoirs, a substantial fraction of seismic events can be excluded from the official catalogue due to an inability to clearly identify seismic-phase onsets. Empirical MFP can improve the effectiveness of current seismic detection and location methodologies by using conventionally located events with higher signal-to-noise ratios as master events to define wavefield templates that could then be used to map normally discarded indistinct seismicity. Since MFP does not require picking, it can be carried out automatically and rapidly once suitable templates are defined. In this application, we extend MFP by constructing local-distance empirical master templates using Southern California Earthquake Data Center archived waveform data of events originating within the Salton Sea Geothermal Field. We compare the empirical templates to continuous seismic data collected between 1 January 2008 and 31 December 2011. The empirical MFP method successfully identifies 6249 additional events, while the original catalogue reported 4352 events. The majority of these new events are lower-magnitude events with magnitudes between M0.2-M0.8. The increased spatial-temporal resolution of the microseismicity map within the geothermal field illustrates how empirical MFP, when combined with conventional methods, can significantly improve seismic network detection capabilities, which can aid in long-term sustainability and monitoring of managed underground reservoirs.

  7. Experimental Seismic Event-screening Criteria at the Prototype International Data Center

    Science.gov (United States)

    Fisk, M. D.; Jepsen, D.; Murphy, J. R.

    - Experimental seismic event-screening capabilities are described, based on the difference of body-and surface-wave magnitudes (denoted as Ms:mb) and event depth. These capabilities have been implemented and tested at the prototype International Data Center (PIDC), based on recommendations by the IDC Technical Experts on Event Screening in June 1998. Screening scores are presented that indicate numerically the degree to which an event meets, or does not meet, the Ms:mb and depth screening criteria. Seismic events are also categorized as onshore, offshore, or mixed, based on their 90% location error ellipses and an onshore/offshore grid with five-minute resolution, although this analysis is not used at this time to screen out events.Results are presented of applications to almost 42,000 events with mb>=3.5 in the PIDC Standard Event Bulletin (SEB) and to 121 underground nuclear explosions (UNE's) at the U.S. Nevada Test Site (NTS), the Semipalatinsk and Novaya Zemlya test sites in the Former Soviet Union, the Lop Nor test site in China, and the Indian, Pakistan, and French Polynesian test sites. The screening criteria appear to be quite conservative. None of the known UNE's are screened out, while about 41 percent of the presumed earthquakes in the SEB with mb>=3.5 are screened out. UNE's at the Lop Nor, Indian, and Pakistan test sites on 8 June 1996, 11 May 1998, and 28 May 1998, respectively, have among the lowest Ms:mb scores of all events in the SEB.To assess the validity of the depth screening results, comparisons are presented of SEB depth solutions to those in other bulletins that are presumed to be reliable and independent. Using over 1600 events, the comparisons indicate that the SEB depth confidence intervals are consistent with or shallower than over 99.8 percent of the corresponding depth estimates in the other bulletins. Concluding remarks are provided regarding the performance of the experimental event-screening criteria, and plans for future

  8. Evaluation of Multi Canister Overpack (MCO) Handling Machine Uplift Restraint for a Seismic Event During Repositioning Operations

    Energy Technology Data Exchange (ETDEWEB)

    SWENSON, C.E.

    2000-05-15

    Insertion of the Multi-Canister Overpack (MCO) assemblies into the Canister Storage Building (CSB) storage tubes involves the use of the MCO Handling Machine (MHM). During MCO storage tube insertion operations, inadvertent movement of the MHM is prevented by engaging seismic restraints (''active restraints'') located adjacent to both the bridge and trolley wheels. During MHM repositioning operations, the active restraints are not engaged. When the active seismic restraints are not engaged, the only functioning seismic restraints are non-engageable (''passive'') wheel uplift restraints which function only if the wheel uplift is sufficient to close the nominal 0.5-inch gap at the uplift restraint interface. The MHM was designed and analyzed in accordance with ASME NOG-1-1995. The ALSTHOM seismic analysis reported seismic loads on the MHM uplift restraints and EDERER performed corresponding structural calculations to demonstrate structural adequacy of the seismic uplift restraint hardware. The ALSTHOM and EDERER calculations were performed for a parked MHM with the active seismic restraints engaged, resulting in uplift restraint loading only in the vertical direction. In support of development of the CSB Safety Analysis Report (SAR), an evaluation of the MHM seismic response was requested for the case where the active seismic restraints are not engaged. If a seismic event occurs during MHM repositioning operations, a moving contact at a seismic uplift restraint would introduce a friction load on the restraint in the direction of the movement. These potential horizontal friction loads on the uplift restraints were not included in the existing restraint hardware design calculations. One of the purposes of the current evaluation is to address the structural adequacy of the MHM seismic uplift restraints with the addition of the horizontal friction associated with MHM repositioning movements.

  9. Source mechanisms of mining-related seismic events in the Far West Rand, South Africa

    CSIR Research Space (South Africa)

    Kassa, BB

    2009-09-01

    Full Text Available Meeting and Exhibition Swaziland, 16 - 18 September 2009, pages 69 - 72 Source mechanisms of mining-related seismic events in the Far West Rand, South Africa BB Kassa1, J Julià2, AA Nyblade2 and RJ Durrheim1,3 1University of the Witwatersrand... layer between the gold- bearing reefs, the forward problem can be formulated as [Trifu et al., 2000; Julia et al., 2009] u=cF:M where u = vector of spectral displacements, c = 1/(4pV3R), ρ = density, V = P- or S-wave velocity, R = hypocentral...

  10. Investigating the Capability to Extract Impulse Response Functions From Ambient Seismic Noise Using a Mine Collapse Event

    Science.gov (United States)

    Kwak, Sangmin; Song, Seok Goo; Kim, Geunyoung; Cho, Chang Soo; Shin, Jin Soo

    2017-10-01

    Using recordings of a mine collapse event (Mw 4.2) in South Korea in January 2015, we demonstrated that the phase and amplitude information of impulse response functions (IRFs) can be effectively retrieved using seismic interferometry. This event is equivalent to a single downward force at shallow depth. Using quantitative metrics, we compared three different seismic interferometry techniques—deconvolution, coherency, and cross correlation—to extract the IRFs between two distant stations with ambient seismic noise data. The azimuthal dependency of the source distribution of the ambient noise was also evaluated. We found that deconvolution is the best method for extracting IRFs from ambient seismic noise within the period band of 2-10 s. The coherency method is also effective if appropriate spectral normalization or whitening schemes are applied during the data processing.

  11. Relocating Seismicity on the Arctic Plate Boundary Using Teleseismic and Regional Phases and a Bayesian Multiple Event Locator

    Science.gov (United States)

    Gibbons, Steven J.; Dahl-Jensen, Trine; Kværna, Tormod; Larsen, Tine B.; Paulsen, Berit; Voss, Peter

    2016-04-01

    The tectonophysics of plate boundaries are illuminated by the pattern of seismicity - and the ability to locate seismic events accurately depends upon the number and quality of observations, the distribution of recording stations, and how well the traveltimes of seismic phases are modelled. The boundary between the Eurasian and North American plates between 70 and 84 degrees North hosts large seismic events which are well recorded teleseismically and many more 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 15 years, 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 quiet and accessible sites, and the expense and difficult logistics of deploying and maintaining stations. New deployments and upgrades to stations on Greenland, Svalbard, and the islands 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 catalog of over 1000 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. The Bayesloc program, a Bayesian hierarchical multiple event location algorithm, has been used to relocate the full set of events iteratively and this has resulted in a significant reduction in the spread in hypocenter estimates for both large and small events. Whereas single event location algorithms minimize the vector of time residuals on an event-by-event basis, Bayesloc favours the hypocenters which

  12. Seismic moment tensor resolution on a local scale: Simulated rockburst and mine-induced seismic events in the Kopanang gold mine, South Africa

    CSIR Research Space (South Africa)

    Sileny, J

    2006-08-01

    Full Text Available Resolution on a Local Scale: Simulated Rockburst and Mine-induced Seismic Events in the Kopanang Gold Mine, South Africa JAN S? I? LENY? 1 and ALEXANDER MILEV2 Abstract?Seismic records contain information about the effect of the source as well as the effect... is expected compared to the simple shear slip along a pre-existing fault plane (HASEGAWA et al., 1989). To test the resolution, it is useful to invert seismograms generated by a controlled source, with a known mechanism. This can be achieved by a blast...

  13. ANALYSIS OF SEISMIC ACTIVITY IN COSTA RICA DURING 2010 AND SUMMARY OF MAJOR SEISMIC EVENTS IN COSTA RICA FROM 1983 TO 2012

    OpenAIRE

    Segura-Torres, Juan; Quintero-Quintero, Ronnie; Burgoa-Rosso, Billy; Jiménez-Urrutia, Walter

    2014-01-01

    The goal of this work is to analyze the seismic activity recorded by the OVSICORI-UNA seismic network in 2010; we also gathered information of the main events felt since 1984. The earthquake location is made using P- and S- arrivals, and source parameters are characterized using polarities and waveforms. The subduction process of the Cocos tectonic plate beneath the Caribbean one caused two important earthquakes of magnitudes 6.2 and 6.1 Ml in the southwest of Puerto Quepos, and another one o...

  14. Ground truth seismic events and location capability at Degelen mountain, Kazakhstan

    Science.gov (United States)

    Trabant, C.; Thurber, C.; Leith, W.

    2002-01-01

    We utilized nuclear explosions from the Degelen Mountain sub-region of the Semipalatinsk Test Site (STS), Kazakhstan, to assess seismic location capability directly. Excellent ground truth information for these events was either known or was estimated from maps of the Degelen Mountain adit complex. Origin times were refined for events for which absolute origin time information was unknown using catalog arrival times, our ground truth location estimates, and a time baseline provided by fixing known origin times during a joint hypocenter determination (JHD). Precise arrival time picks were determined using a waveform cross-correlation process applied to the available digital data. These data were used in a JHD analysis. We found that very accurate locations were possible when high precision, waveform cross-correlation arrival times were combined with JHD. Relocation with our full digital data set resulted in a mean mislocation of 2 km and a mean 95% confidence ellipse (CE) area of 6.6 km2 (90% CE: 5.1 km2), however, only 5 of the 18 computed error ellipses actually covered the associated ground truth location estimate. To test a more realistic nuclear test monitoring scenario, we applied our JHD analysis to a set of seven events (one fixed) using data only from seismic stations within 40?? epicentral distance. Relocation with these data resulted in a mean mislocation of 7.4 km, with four of the 95% error ellipses covering less than 570 km2 (90% CE: 438 km2), and the other two covering 1730 and 8869 km2 (90% CE: 1331 and 6822 km2). Location uncertainties calculated using JHD often underestimated the true error, but a circular region with a radius equal to the mislocation covered less than 1000 km2 for all events having more than three observations. ?? 2002 Elsevier Science B.V. All rights reserved.

  15. Seismic source associated with the repetitive events recorded at the Nevado del Huila volcano - Colombia in November 2008

    Science.gov (United States)

    Trujillo, N.; Valdes-González, C. M.; White, R.; Dawson, P. B.; McCausland, W. A.; Santacoloma, C.

    2016-12-01

    The Nevado del Huila Volcano recorded an eruption on November 21st, 2008. This eruptive event was preceded by approximately 11,200 seismic events associated to fluids dynamic inside volcanic conduits. These seismic signals were classified as Hybrid events (HB), Long Period events (LP) and Drumbeat events, and they presented as fundamental characteristic, great regularity in the time, i. e. their waveforms and their bandwidths were very similar to each other. Cardona et al. (2009) made a first analysis of these signals and proposed the existence of two seismic families: the first integrated by LP events and HB events registered in the period, November 9th to November 21st; and second family composed by the Drumbeats events registered between November 20th and 21st. Our project took as starting point the work of Cardona et al. (2009); we establish the degree of similarity between events of each of the two families proposed by Cardona et al. (2009). First, we made a temporal analysis by using the Hilbert Transform, and then applied the cross-correlation technique. Finally a stacking of the signals with correlation coefficients > 0.9, was obtained. The results were: 8000 events with correlation coefficients > 0.9 and the existence of six possible seismic families. A detailed analysis of the seismic signals obtained through the stacking allowed us to conclude the existence of four families, the first one recorded between the 4th to 18th of November, the second one for the drumbeat events recorded on November 11th, the third one for the seismicity recorded between the 14th and 21st of November, and the four one for the drumbeat events registered on November 20th and 21st. We suggest that each of these families was associated with a different seismic source; so, the first and third families were possibly associated to mechanisms like brittle fracturing that can occur in weak areas where cracks or conduits intersect, and where acoustic resonance can occur, and the second

  16. Blind Source Separation of Seismic Events with Independent Component Analysis: CTBT related exercise

    Science.gov (United States)

    Rozhkov, Mikhail; Kitov, Ivan

    2015-04-01

    Blind Source Separation (BSS) methods used in signal recovery applications are attractive for they use minimal a priori information about the signals they are dealing with. Homomorphic deconvolution and cepstrum estimation are probably the only methods used in certain extent in CTBT applications that can be attributed to the given branch of technology. However Expert Technical Analysis (ETA) conducted in CTBTO to improve the estimated values for the standard signal and event parameters according to the Protocol to the CTBT may face problems which cannot be resolved with certified CTBTO applications and may demand specific techniques not presently used. The problem to be considered within the ETA framework is the unambiguous separation of signals with close arrival times. Here, we examine two scenarios of interest: (1) separation of two almost co-located explosions conducted within fractions of seconds, and (2) extraction of explosion signals merged with wavetrains from strong earthquake. The importance of resolving the problem related to case 1 is connected with the correct explosion yield estimation. Case 2 is a well-known scenario of conducting clandestine nuclear tests. While the first case can be approached somehow with the means of cepstral methods, the second case can hardly be resolved with the conventional methods implemented at the International Data Centre, especially if the signals have close slowness and azimuth. Independent Component Analysis (in its FastICA implementation) implying non-Gaussianity of the underlying processes signal's mixture is a blind source separation method that we apply to resolve the mentioned above problems. We have tested this technique with synthetic waveforms, seismic data from DPRK explosions and mining blasts conducted within East-European platform as well as with signals from strong teleseismic events (Sumatra, April 2012 Mw=8.6, and Tohoku, March 2011 Mw=9.0 earthquakes). The data was recorded by seismic arrays of the

  17. Analysis of low-frequency seismic signals generated during a multiple-iceberg calving event at Jakobshavn Isbræ, Greenland

    Science.gov (United States)

    Walter, Fabian; Amundson, Jason M.; O'Neel, Shad; Truffer, Martin; Fahnestock, Mark; Fricker, Helen A.

    2012-01-01

    We investigated seismic signals generated during a large-scale, multiple iceberg calving event that occurred at Jakobshavn Isbræ, Greenland, on 21 August 2009. The event was recorded by a high-rate time-lapse camera and five broadband seismic stations located within a few hundred kilometers of the terminus. During the event two full-glacier-thickness icebergs calved from the grounded (or nearly grounded) terminus and immediately capsized; the second iceberg to calve was two to three times smaller than the first. The individual calving and capsize events were well-correlated with the radiation of low-frequency seismic signals (icebergs generated a larger seismic signal.

  18. Regularized Deterministic Annealing Hidden Markov Models for Identificationand Analysis of Seismic and Aseismic events.

    Science.gov (United States)

    Granat, R. A.; Clayton, R.; Kedar, S.; Kaneko, Y.

    2003-12-01

    We employ a robust hidden Markov model (HMM) based technique to perform statistical pattern analysis of suspected seismic and aseismic events in the poorly explored period band of minutes to hours. The technique allows us to classify known events and provides a statistical basis for finding and cataloging similar events represented elsewhere in the observations. In this work, we focus on data collected by the Southern California TriNet system. The hidden Markov model (HMM) approach assumes that the observed data has been generated by an unobservable dynamical statistical process. The process is of a particular form such that each observation is coincident with the system being in a particular discrete state. The dynamics are the model are constructed so that the next state is directly dependent only on the current state -- it is a first order Markov process. The model is completely described by a set of parameters: the initial state probabilities, the first order Markov chain state-to-state transition probabilities, and the probability distribution of observable outputs associated with each state. Application of the model to data involves optimizing these model parameters with respect to some function of the observations, typically the likelihood of the observations given the model. Our work focused on the fact that this objective function has a number of local maxima that is exponential in the model size (the number of states). This means that not only is it very difficult to discover the global maximum, but also that results can vary widely between applications of the model. For some domains which employ HMMs for such purposes, such as speech processing, sufficient a priori information about the system is available to avoid this problem. However, for seismic data in general such a priori information is not available. Our approach involves analytical location of sub-optimal local maxima; once the locations of these maxima have been found, then we can employ a

  19. Analysis of the behaviour of the CLIC_SiD iron return yoke during a seismic event

    CERN Document Server

    Duarte Ramos, F.

    2012-01-01

    The iron return yoke of the CLIC SiD detector concept is composed of three barrel rings and two endcap discs which, during a seismic event, are subjected to horizontal and vertical accelerations that can result in both a mechanical failure of internal structural elements and high deformations which can lead to unwanted collisions with other internal or external detector elements, as well as the walls of the experimental cavern. This report presents the results from the analysis of the return yoke barrel rings and endcaps under a seismic event load case.

  20. Fully Autonomous Multiplet Event Detection: Application to Local-Distance Monitoring of Blood Falls Seismicity

    Energy Technology Data Exchange (ETDEWEB)

    Carmichael, Joshua Daniel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carr, Christina [Univ. of Alaska, Fairbanks, AK (United States); Pettit, Erin C. [Univ. of Alaska, Fairbanks, AK (United States)

    2015-06-18

    We apply a fully autonomous icequake detection methodology to a single day of high-sample rate (200 Hz) seismic network data recorded from the terminus of Taylor Glacier, ANT that temporally coincided with a brine release episode near Blood Falls (May 13, 2014). We demonstrate a statistically validated procedure to assemble waveforms triggered by icequakes into populations of clusters linked by intra-event waveform similarity. Our processing methodology implements a noise-adaptive power detector coupled with a complete-linkage clustering algorithm and noise-adaptive correlation detector. This detector-chain reveals a population of 20 multiplet sequences that includes ~150 icequakes and produces zero false alarms on the concurrent, diurnally variable noise. Our results are very promising for identifying changes in background seismicity associated with the presence or absence of brine release episodes. We thereby suggest that our methodology could be applied to longer time periods to establish a brine-release monitoring program for Blood Falls that is based on icequake detections.

  1. Spatial correlation for horizontal and vertical components of acceleration from northern Iran seismic events

    Science.gov (United States)

    Garakaninezhad, Alireza; Bastami, Morteza; Soghrat, Mohammad Reza

    2017-11-01

    The evaluation of seismic risk of spatially distributed systems requires the spatial correlation model for ground motion intensity measures. This study investigates the spatial correlation of four earthquakes recorded in northern Iran. The intra-event spatial correlation for both horizontal and vertical components of spectral acceleration at eight periods in the range of 0.0-3.0 s is estimated using geostatistical tools. An exponential form is chosen to fit experimental semivariograms, and the correlation ranges of spectral accelerations as a function of period are derived. The results show similar trend of correlation ranges for both components. It should be mentioned that the ranges for the vertical component, in general, are higher than those observed for the horizontal one. For both components, the correlation ranges as a function of period are divided into three segments. The first and the third one are increasing while the second one is decreasing with increasing period.

  2. Automatic seismic event detection using migration and stacking: a performance and parameter study in Hengill, southwest Iceland

    Science.gov (United States)

    Wagner, F.; Tryggvason, A.; Roberts, R.; Lund, B.; Gudmundsson, Ó.

    2017-06-01

    We investigate the performance of a seismic event detection algorithm using migration and stacking of seismic traces. The focus lies on determining optimal data dependent detection parameters for a data set from a temporary network in the volcanically active Hengill area, southwest Iceland. We test variations of the short-term average to long-term average and Kurtosis functions, calculated from filtered seismic traces, as input data. With optimal detection parameters, our algorithm identified 94 per cent (219 events) of the events detected by the South Iceland Lowlands (SIL) system, that is, the automatic system routinely used on Iceland, as well as a further 209 events, previously missed. The assessed number of incorrect (false) detections was 25 per cent for our algorithm, which was considerably better than that from SIL (40 per cent). Empirical tests show that well-functioning processing parameters can be effectively selected based on analysis of small, representative subsections of data. Our migration approach is more computationally expensive than some alternatives, but not prohibitively so, and it appears well suited to analysis of large swarms of low magnitude events with interevent times on the order of seconds. It is, therefore, an attractive, practical tool for monitoring of natural or anthropogenic seismicity related to, for example, volcanoes, drilling or fluid injection.

  3. The DOE Model for Improving Seismic Event Locations Using Travel Time Corrections: Description and Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Hipp, J.R.; Moore, S.G.; Shepherd, E.; Young, C.J.

    1998-10-20

    The U.S. National Laboratories, under the auspices of the Department of Energy, have been tasked with improv- ing the capability of the United States National Data Center (USNDC) to monitor compliance with the Comprehen- sive Test Ban Trea~ (CTBT). One of the most important services which the USNDC must provide is to locate suspicious events, preferably as accurately as possible to help identify their origin and to insure the success of on-site inspections if they are deemed necessary. The seismic location algorithm used by the USNDC has the capability to generate accurate locations by applying geographically dependent travel time corrections, but to date, none of the means, proposed for generating and representing these corrections has proven to be entirely satisfactory. In this presentation, we detail the complete DOE model for how regional calibration travel time information gathered by the National Labs will be used to improve event locations and provide more realistic location error esti- mates. We begin with residual data and error estimates from ground truth events. Our model consists of three parts: data processing, data storage, and data retrieval. The former two are effectively one-time processes, executed in advance before the system is made operational. The last step is required every time an accurate event location is needed. Data processing involves applying non-stationary Bayesian kriging to the residwd data to densifi them, and iterating to find the optimal tessellation representation for the fast interpolation in the data retrieval task. Both the kriging and the iterative re-tessellation are slow, computationally-expensive processes but this is acceptable because they are performed off-line, before any events are to be located. In the data storage task, the densified data set is stored in a database and spatially indexed. Spatial indexing improves the access efficiency of the geographically-ori- ented data requests associated with event location

  4. Response of the ionospheric electron density to different types of seismic events

    Directory of Open Access Journals (Sweden)

    Y. He

    2011-08-01

    Full Text Available The electron density data recorded by the Langmuir Probe Instrument (ISL, Instrument Sonde de Langmuir onboard the DEMETER satellite have been collected for nearly 4 yr (during 2006–2009 to perform a statistical analysis. During this time, more than 7000 earthquakes with a magnitude larger than or equal to 5.0 occurred all over the world. For the statistical studies, all these events have been divided into various categories on the basis of the seismic information, including Southern or Northern Hemisphere earthquakes, inland or sea earthquakes, earthquakes at different magnitude levels, earthquakes at different depth levels, isolated events and all events. To distinguish the pre-earthquake anomalies from the possible ionospheric anomalies related to the geomagnetic activity, the data were filtered with the Kp index. The statistical results obviously show that the electron density increases close to the epicentres both in the Northern and the Southern Hemisphere, but the position of the anomaly is slightly shifted to the north in the Northern Hemisphere and to the south in the Southern Hemisphere. The electron density related to both inland and sea earthquakes presents an anomaly approximately close to the epicentres, but the anomaly for sea earthquakes is more significant than for inland earthquakes. The intensity of the anomalies is enhanced when the magnitude increases and is reduced when the depth increases. A similar anomaly can also be seen in the statistical results concerning the isolated earthquakes. All these statistical results can help to better understand the preparation process of the earthquakes and their influence up to the ionospheric levels.

  5. Role of the masonry in paintings during a seismic event analyzed by infrared vision

    Science.gov (United States)

    López, F.; Sfarra, S.; Ibarra-Castanedo, C.; Ambrosini, D.; Maldague, X. P. V.

    2015-06-01

    In this work, pulsed phase thermography (PPT), principal component thermography (PCT), and partial least squares thermography (PLST) techniques were applied in order to detect the masonry texture, as well as to map the subsurface damages formed beneath three different mural paintings. The latter were inspected after the 2009 earthquake, i.e., the seismic event that devastated L'Aquila City (Italy) and its surroundings. The mural supports explored by infrared thermography (IRT) are constituted by a single leaf, and the sides of the inspected paintings are confined by marble frames or by buried horizontal and vertical structures. Hence, the analyzed objects can be considered as monolithic structures. IRT can help to understand the masonry morphology, e.g. if there exist structural continuity between the arriccio layer (the first coat of plaster) and the support. In the present case, the heating phase was provided by lamps or propane gas and feature detection was enhanced by advanced signal processing. A comparison among the results is presented. Two of the three objects analyzed, painted by the art masters Serbucci and Avicola, are preserved inside Santa Maria della Croce di Roio Church in Roio Poggio (L'Aquila, Italy); they were executed on two masonries built in different periods. The last one was realized in Montorio al Vomano (Teramo, Italy) on the internal cloister of the Zoccolanti's Church (undated). The villages are separated by 50 km as the crow flies. Finally, near-infrared reflectography (NIRR) technique was also used to investigate the condition of the painting layer.

  6. Fractal analysis of GPS time series for early detection of disastrous seismic events

    Science.gov (United States)

    Filatov, Denis M.; Lyubushin, Alexey A.

    2017-03-01

    A new method of fractal analysis of time series for estimating the chaoticity of behaviour of open stochastic dynamical systems is developed. The method is a modification of the conventional detrended fluctuation analysis (DFA) technique. We start from analysing both methods from the physical point of view and demonstrate the difference between them which results in a higher accuracy of the new method compared to the conventional DFA. Then, applying the developed method to estimate the measure of chaoticity of a real dynamical system - the Earth's crust, we reveal that the latter exhibits two distinct mechanisms of transition to a critical state: while the first mechanism has already been known due to numerous studies of other dynamical systems, the second one is new and has not previously been described. Using GPS time series, we demonstrate efficiency of the developed method in identification of critical states of the Earth's crust. Finally we employ the method to solve a practically important task: we show how the developed measure of chaoticity can be used for early detection of disastrous seismic events and provide a detailed discussion of the numerical results, which are shown to be consistent with outcomes of other researches on the topic.

  7. Risks posed by large seismic events in the gold mining districts of South Africa

    CSIR Research Space (South Africa)

    Durrheim, RJ

    2011-01-01

    Full Text Available of seismic monitoring and to ensure continuity, especially as mines change hands. The Klerksdorp and Free State gold mining districts are incorporating the risks of seismicity in their disaster management plans, and Johannesburg is urged to do likewise. Some...

  8. Source parameters of seismic events potentially associated with damage in block 33/34 of the Kiirunavaara mine (Sweden)

    Science.gov (United States)

    Nordström, Emilia; Dineva, Savka; Nordlund, Erling

    2017-12-01

    Forty-six mining-induced seismic events with moment magnitude between -1.2 and 2.1 that possibly caused damage were studied. The events occurred between 2008 and 2013 at mining level 850-1350 m in the Kiirunavaara Mine (Sweden). Hypocenter locations were refined using from 6 to 130 sensors at distances of up to 1400 m. The source parameters of the events were re-estimated using spectral analysis with a standard Brune model (slope -2). The radiated energy for the studied events varied from 4.7 × 10-1 to 3.8 × 107 J, the source radii from 4 to 110 m, the apparent stress from 6.2 × 102 to 1.1 × 106 Pa, energy ratio ( E s/ E p) from 1.2 to 126, and apparent volume from 1.8 × 103 to 1.1 × 107 m3. 90% of the events were located in the footwall, close to the ore contact. The events were classified as shear/fault slip (FS) or non-shear (NS) based on the E s/ E p ratio (>10 or <10). Out of 46 events 15 events were classified as NS located almost in the whole range between 840 and 1360 m, including many events below the production. The rest 31 FS events were concentrated mostly around the production levels and slightly below them. The relationships between some source parameters and seismic moment/moment magnitude showed dependence on the type of the source mechanism. The energy and the apparent stress were found to be three times larger for FS events than for NS events.

  9. Historical and Paleo Events as an input for Seismic And Associated Natural Hazard Assessment of Javakheti highland (South Georgia)

    Science.gov (United States)

    Elashvili, M.; Javakhishvili, Z.; Godoladze, T.; Karakhanyan, A.; Sukhishvili, L.; Nikolaeva, E.; Sokhadze, G.; Avanesyan, M.

    2012-12-01

    of historical earthquakes of 1899 and 1089, as well as Archaeo-Seismological site along the Javakheti seismic fault will be presented. History on Natural Disasters in the region can be complemented by Bertakana Paleo-Landslide, to be discussed separately as one of the mega events in the Area. The mentioned events are considered as an important input for Seismic Hazard Assessment of Javakheti Region.

  10. Map Showing Seacliff Response to Climatic and Seismic Events, Seabright Beach, Santa Cruz County, California

    Science.gov (United States)

    Hapke, Cheryl J.; Richmond, Bruce M.; D'Iorio, Mimi M.

    2002-01-01

    Introduction The coastal cliffs along much of the central California coast are actively retreating. Large storms and periodic earthquakes are responsible for most of the documented sea cliff slope failures. Long-term average erosion rates calculated for this section of coast do not provide the spatial or temporal data resolution necessary to identify the processes responsible for retreat of the sea cliffs where episodic retreat threatens homes and community infrastructure. Research suggests that more erosion occurs along the California coast over a short time scale, during periods of severe storms or seismic activity, than occurs during decades of normal weather or seismic quiescence. This is the third map in a series of maps prepared to document the processes of short-term sea cliff retreat through the identification of slope failure styles, spatial variability of failures, and temporal variation in retreat amounts in an area that has been identified as an erosion hotspot. This map presents sea cliff failure and retreat data from the Seabright Beach section, California, which is located on the east side of Santa Cruz along the northern Monterey Bay coast. The data presented in this map series provide high-resolution spatial and temporal information on the location, amount, and processes of sea cliff retreat in Santa Cruz, California. These data show the response of the sea cliffs to both large magnitude earthquakes and severe climatic events such as El Ni?os; this information may prove useful in predicting the future response of the cliffs to events of similar magnitude. The map data can also be incorporated into Global Information System (GIS) for use by researchers and community planners. During this study we developed a method for investigating short-term processes of sea cliff evolution using rectified photographic stereo models. This method allows us to document the linear extent of cliff failures, the spatial and temporal relationship between failures, and

  11. Discrimination of Mine Seismic Events and Blasts Using the Fisher Classifier, Naive Bayesian Classifier and Logistic Regression

    Science.gov (United States)

    Dong, Longjun; Wesseloo, Johan; Potvin, Yves; Li, Xibing

    2016-01-01

    Seismic events and blasts generate seismic waveforms that have different characteristics. The challenge to confidently differentiate these two signatures is complex and requires the integration of physical and statistical techniques. In this paper, the different characteristics of blasts and seismic events were investigated by comparing probability density distributions of different parameters. Five typical parameters of blasts and events and the probability density functions of blast time, as well as probability density functions of origin time difference for neighbouring blasts were extracted as discriminant indicators. The Fisher classifier, naive Bayesian classifier and logistic regression were used to establish discriminators. Databases from three Australian and Canadian mines were established for training, calibrating and testing the discriminant models. The classification performances and discriminant precision of the three statistical techniques were discussed and compared. The proposed discriminators have explicit and simple functions which can be easily used by workers in mines or researchers. Back-test, applied results, cross-validated results and analysis of receiver operating characteristic curves in different mines have shown that the discriminator for one of the mines has a reasonably good discriminating performance.

  12. Space-time clustering of seismic events and hazard assessment in the Zabrze-Bielszowice coal mine, Poland

    Energy Technology Data Exchange (ETDEWEB)

    Lesniak, A.; Isakow, Z. [AGH University of Science & Technology, Krakow (Poland)

    2009-07-15

    The results of the statistical analysis of seismic activity recorded in the 'Zabrze-Bielszowice' coal mine in Poland are presented in this article. The monitoring was conducted by a small network consisting of four triaxial geophones deployed in vertical holes in the roof. For over 1000 seismic events recorded during the two month's experiment, the location of sources was realized. The seismic sources were mostly located ahead of the active face of the long wall. Since the first day of the monitoring, cluster analysis was sequentially performed for increasing number of sources. At the end of the experiment, 31 clusters were identified. They consisted of different numbers of events and were separated in space. About 40% of the events were not included in the clusters. For each large cluster, hazard analysis was separately performed. The hazard function evaluated for the largest cluster was compared with hypocenters of high energy tremors (E > 1000 J) recorded by the geophones in that area. For some cases, recorded tremors occurred after an abrupt decrease of hazard function, but only one of them was located in the vicinity of the appropriate cluster. We concluded that for the analyzed cluster, a correlation between evaluated hazard function and time occurrences of the high energy tremors existed. Except for one case, there is no space correlation between analyzed clusters and high energy tremors.

  13. Nonlinear Methodologies for Identifying Seismic Event and Nuclear Explosion Using Random Forest, Support Vector Machine, and Naive Bayes Classification

    Directory of Open Access Journals (Sweden)

    Longjun Dong

    2014-01-01

    Full Text Available The discrimination of seismic event and nuclear explosion is a complex and nonlinear system. The nonlinear methodologies including Random Forests (RF, Support Vector Machines (SVM, and Naïve Bayes Classifier (NBC were applied to discriminant seismic events. Twenty earthquakes and twenty-seven explosions with nine ratios of the energies contained within predetermined “velocity windows” and calculated distance are used in discriminators. Based on the one out cross-validation, ROC curve, calculated accuracy of training and test samples, and discriminating performances of RF, SVM, and NBC were discussed and compared. The result of RF method clearly shows the best predictive power with a maximum area of 0.975 under the ROC among RF, SVM, and NBC. The discriminant accuracies of RF, SVM, and NBC for test samples are 92.86%, 85.71%, and 92.86%, respectively. It has been demonstrated that the presented RF model can not only identify seismic event automatically with high accuracy, but also can sort the discriminant indicators according to calculated values of weights.

  14. Automated Sensor Tuning for Seismic Event Detection at a Carbon Capture, Utilization, and Storage Site, Farnsworth Unit, Ochiltree County, Texas

    Science.gov (United States)

    Ziegler, A.; Balch, R. S.; Knox, H. A.; Van Wijk, J. W.; Draelos, T.; Peterson, M. G.

    2016-12-01

    We present results (e.g. seismic detections and STA/LTA detection parameters) from a continuous downhole seismic array in the Farnsworth Field, an oil field in Northern Texas that hosts an ongoing carbon capture, utilization, and storage project. Specifically, we evaluate data from a passive vertical monitoring array consisting of 16 levels of 3-component 15Hz geophones installed in the field and continuously recording since January 2014. This detection database is directly compared to ancillary data (i.e. wellbore pressure) to determine if there is any relationship between seismic observables and CO2 injection and pressure maintenance in the field. Of particular interest is detection of relatively low-amplitude signals constituting long-period long-duration (LPLD) events that may be associated with slow shear-slip analogous to low frequency tectonic tremor. While this category of seismic event provides great insight into dynamic behavior of the pressurized subsurface, it is inherently difficult to detect. To automatically detect seismic events using effective data processing parameters, an automated sensor tuning (AST) algorithm developed by Sandia National Laboratories is being utilized. AST exploits ideas from neuro-dynamic programming (reinforcement learning) to automatically self-tune and determine optimal detection parameter settings. AST adapts in near real-time to changing conditions and automatically self-tune a signal detector to identify (detect) only signals from events of interest, leading to a reduction in the number of missed legitimate event detections and the number of false event detections. Funding for this project is provided by the U.S. Department of Energy's (DOE) National Energy Technology Laboratory (NETL) through the Southwest Regional Partnership on Carbon Sequestration (SWP) under Award No. DE-FC26-05NT42591. Additional support has been provided by site operator Chaparral Energy, L.L.C. and Schlumberger Carbon Services. Sandia National

  15. Optically-based Sensor System for Critical Nuclear Facilities Post-Event Seismic Structural Assessment

    Energy Technology Data Exchange (ETDEWEB)

    McCallen, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Petrone, Floriana [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Buckle, Ian [Univ. of Nevada, Reno, NV (United States); Wu, Suiwen [Univ. of Nevada, Reno, NV (United States); Coates, Jason [California State Univ., Chico, CA (United States)

    2017-09-30

    The U.S. Department of Energy (DOE) has ownership and operational responsibility for a large enterprise of nuclear facilities that provide essential functions to DOE missions ranging from national security to discovery science and energy research. These facilities support a number of DOE programs and offices including the National Nuclear Security Administration, Office of Science, and Office of Environmental Management. With many unique and “one of a kind” functions, these facilities represent a tremendous national investment, and assuring their safety and integrity is fundamental to the success of a breadth of DOE programs. Many DOE critical facilities are located in regions with significant natural phenomenon hazards including major earthquakes and DOE has been a leader in developing standards for the seismic analysis of nuclear facilities. Attaining and sustaining excellence in nuclear facility design and management must be a core competency of the DOE. An important part of nuclear facility management is the ability to monitor facilities and rapidly assess the response and integrity of the facilities after any major upset event. Experience in the western U.S. has shown that understanding facility integrity after a major earthquake is a significant challenge which, lacking key data, can require extensive effort and significant time. In the work described in the attached report, a transformational approach to earthquake monitoring of facilities is described and demonstrated. An entirely new type of optically-based sensor that can directly and accurately measure the earthquake-induced deformations of a critical facility has been developed and tested. This report summarizes large-scale shake table testing of the sensor concept on a representative steel frame building structure, and provides quantitative data on the accuracy of the sensor measurements.

  16. Reducing Systematic Errors for Seismic Event Locations Using a Model Incorporating Anisotropic Regional Structures

    National Research Council Canada - National Science Library

    Smith, Gideon P; Wiens, Douglas A

    2006-01-01

    ...) to predict travel times of P-wave propagation at distances of 2 - 14 degrees. At such distances, the phase Pn is in the seismic phase that is most frequently reported and that thus controls the location accuracy...

  17. Extended sources of the main events of the Umbria-Marche (1997 seismic sequence inverted from geophysical data

    Directory of Open Access Journals (Sweden)

    M. E. Belardinelli

    2008-06-01

    Full Text Available The three largest events of the 1997 Umbria-Marche (Italy sequence occurred on September 26, 1997 at 00:33 GMT (Event 1, MW=5.7 and 09:40 GMT (Event 2, MW=6.0 in the Colfiorito area and on the October 14, 1997 at 15:23 (Event 3, MW=5.6 in the Sellano area. The availability of different sets of geodetic and seismological data allowed several studies to characterize the extended sources of events 1-3. In this work, I review some of the studies that obtain the properties of the seismic sources by inversion of available data. Generally these studies assume the seismic sources as dislocations or distributions of equivalent point sources in elastic half-spaces. Following their chronological order, they model increasing complexities of the sources by using an increasing number of data. Some of the differences between results obtained, such as the top edge depth estimates, are shown to be due to the different approaches used. Commonly a 1-D crustal model is used in inverting strongmotion data. Instead homogeneous elastic half-spaces are mainly assumed in inverting geodetic data to obtain the three main sources of the 1997 Umbria-Marche sequence. Assuming the same crustal structure is important to make comparable results obtained analyzing seismological data or geodetic data separately, as it has been done till now for this sequence.

  18. Relationship between the focal mechanism of magnitude ML 3.3 seismic event induced by mining and distribution of peak ground velocity

    Directory of Open Access Journals (Sweden)

    Dubiński Józef

    2017-01-01

    Full Text Available The relationship between seismic radiation pattern generated by a strong mining induced seismic event and the distribution of peak ground velocity in the epicenter area has been presented. It was a seismic event with the local magnitude ML = 3.3 occurred on June 21, 2016 in the Upper Silesian Coal Basin (USCB in Marcel Mine. Calculated values of the peak ground velocity, taking into account the amplification coefficient, were the basis for the development of the PGVHamp map. The resulting distribution of PGVHamp isolines and the measured velocity amplitudes point to significant differences. That fact indicates that some additional factors can impact on the seismic effect observed on the surface. One of them could be a focal mechanism of seismic event. Focal mechanism of the M=3.3 induced seismic tremor, were calculated by the moment tensor inversion method. The tremor was characterized by a normal slip mechanism with 87% shear component. Comparison of seismic pattern for S-wave at individual stations allowed confirms a relation between directionality of the seismic radiation pattern for S-wave and the recorded peak ground velocities and explain the observed anomaly.

  19. Relationship between the focal mechanism of magnitude ML 3.3 seismic event induced by mining and distribution of peak ground velocity

    Science.gov (United States)

    Dubiński, Józef; Stec, Krystyna; Mutke, Grzegorz

    2017-11-01

    The relationship between seismic radiation pattern generated by a strong mining induced seismic event and the distribution of peak ground velocity in the epicenter area has been presented. It was a seismic event with the local magnitude ML = 3.3 occurred on June 21, 2016 in the Upper Silesian Coal Basin (USCB) in Marcel Mine. Calculated values of the peak ground velocity, taking into account the amplification coefficient, were the basis for the development of the PGVHamp map. The resulting distribution of PGVHamp isolines and the measured velocity amplitudes point to significant differences. That fact indicates that some additional factors can impact on the seismic effect observed on the surface. One of them could be a focal mechanism of seismic event. Focal mechanism of the M=3.3 induced seismic tremor, were calculated by the moment tensor inversion method. The tremor was characterized by a normal slip mechanism with 87% shear component. Comparison of seismic pattern for S-wave at individual stations allowed confirms a relation between directionality of the seismic radiation pattern for S-wave and the recorded peak ground velocities and explain the observed anomaly.

  20. Estimation of Seismic Loss for a Portfolio of Buildings under Bidirectional Horizontal Ground Motions due to a Scenario Cascadia Event

    Directory of Open Access Journals (Sweden)

    Taojun Liu

    2017-10-01

    Full Text Available Earthquake ground motions induced by a scenario event are spatially (partially correlated and (partially coherent. Simulated ground motion records can be used to carry out nonlinear inelastic time history analysis for a portfolio of buildings to estimate the seismic loss, which is advantageous as there is no need to develop and apply empirical ground motion prediction equations and the ductility demand rules, or to search the scenario-compatible recorded records at selected sites that may not exist. Further, if the structures being considered are sensitive to the orientation of the excitation, multiple-component ground motion records are needed. For the simulation of such ground motion records, previous studies have shown that correlation and coherency between any pair of ground motion components need to be incorporated. In this study, the seismic loss of a portfolio of hypothetical buildings in downtown Vancouver under bidirectional horizontal ground motions due to a scenario Cascadia event is estimated by using simulated bidirectional ground motion records that include realistic correlation and coherency characteristics. The hysteretic behaviors of the buildings are described by bidirectional Bouc–Wen model. The results show that the use of unidirectional ground motions and single-degree-of-freedom system structural model may underestimate the aggregated seismic loss.

  1. ShakeMap earthquake scenario: Building Seismic Safety Council 2014 Event Set (BSSC2014)

    Science.gov (United States)

    ,

    2016-01-01

    Seismic design codes often are based on a probabilistic seismic hazard analysis and also a deterministic seismic hazard analysis. While a probabilistic analysis accounts for all possible ruptures, a deterministic analysis only considers a representative subset of ruptures that are based on the same models of earthquake sources as the probabilistic analysis. The deterministic subset of ruptures are characteristic earthquakes on all known active faults. This catalog includes the deterministic ruptures from the 2014 version of the USGS national seismic hazard maps.Ground Motion ModelsFor a given rupture, the ground motion shaking intensity parameters are computed using a weighted combination of ground motion models for reference rock conditions that is consistent with the 2014 version of the USGS national seismic hazard maps. More details are available in the documentation for the 2014 update of the United States national seismic hazard maps.We have employed the OpenQuake hazard library (hazardlib) implementation of the ground motion models. OpenQuake hazardlib provides a broad range of well-tested open-source models.The ground motion parameters in ShakeMap are converted from the average horizontal component, which is given by most ground motion models, to the peak horizontal component. This is necessary for consistency with real-time ShakeMaps. Additional details are discussed in this section of the ShakeMap manual.Site ResponseThe 2014 USGS seismic hazard maps do not account for site response directly. Site conditions are accounted for in the building code separately. However, the scenarios in this catalog include site response in the maps, based on maps of the time-averaged shear-wave velocity in the upper 30 m (Vs30). The input Vs30 grids are a combination of regionally variable models that are available at the USGS Global Vs30 GitHub repository.

  2. A 3-Dimensional Numerical Modelling Study on the Effects of Different Stress Regimes on the Magnitude of Induced Seismic Events

    Science.gov (United States)

    Amini, A.; Eberhardt, E.

    2016-12-01

    Producing oil and gas from shale reservoirs requires permeability enhancement treatments. This is achieved by injecting fluid under pressure to either propagate cracks through the rock (hydraulic fracture) or to stimulate slip across pre-existing fractures (hydroshear), which allows gas or oil to flow more readily into the well bore. After treatment is performed, the fluid is disposed of by injecting it back into the ground. The injection of these fluids, whether related to permeability enhancement or waste water disposal , into deep formations serves to create localized increases in pore pressures and reductions in the effective normal stresses acting on critically stressed faults, resulting in induced earthquakes. There have been numerous reports of anomalous seismic events with high magnitudes felt on surface that have given rise to public concerns. However, it must be recognized that different producing fields in Canada and the U.S. are situated in different tectonic regimes that favour different fault slip mechanisms. This study will explore the importance of stress regime, comparing the generation of induced seismicity under thrust versus strike slip conditions, with focus on their respective magnitudes distributions. To do so, we will first study empirical data pertaining to recorded seismicity related to hydraulic fracture operations with respect to source mechanisms and magnitude distributions. These will be analyzed in parallel with a series of advanced 3-dimensional numerical models using the distinct element code 3DEC to simulate fault slip under different stress regimes.

  3. Mine-induced seismicity at East-Rand proprietary mines

    CSIR Research Space (South Africa)

    Milev, AM

    1995-09-01

    Full Text Available Mining results in seismic activity of varying intensity, from small micro seismic events to larger seismic events, often associated with significant seismic induced damages. This work deals with the understanding of the present seismicity...

  4. Complex rupture process of the March 19, 2013, Rudna mine (Poland) seismic event - local and regional view

    Science.gov (United States)

    Rudzinski, Lukasz; Cesca, Simone; Lizurek, Grzegorz

    2015-04-01

    On March 19th, 2013 a strong shallow induced seismic event struck a mining panel in the room-and-pillar Rudna copper mine, SE Poland. The event caused important damages at the mining tunnel and trapped 19 miners, which were safely rescued few hour later. Despite mining induced seismicity is frequent at this mine, the March 19 event was unusual because of its larger magnitude, its occurrence far from the mining stopes, and because it was accompanied by a strong hazardous rockburst. The mining inspections following the event verified the occurrence of a rockfall with tunnel floor uplift, but also recognized the presence of a faulting structure at the hypocentral location. The availability of three monitoring networks, including local and regional data, short-period and broadband seismometers, as well as surface and in-mine installation, give an optimal set up to determine rupture parameters and compare the performance and results from different installations. We perform waveform and spectral based analysis to infer source properties, with a particular interest to the determination of the rupture processes, using different moment tensor inversion techniques. Our results are surprisingly different, ranging from a dominant thrust mechanism, resolved at closest distances, to a collapse-type rupture, resolved at regional distances. We proof that a complex rupture model is needed to explain all observations and justify these discrepancies. The final scenario indicates that the rupture nucleated as a weaker thrust mechanism, along a pre-existing weakened surface, and continued in a more energetic collapse event. The local surface LUMINEOS network has the potential to resolve both subevents, but not using a standard moment tensor decomposition. We propose here a new moment tensor decomposition and an alternative moment tensor fitting procedure, which can be used to analyze the moment tensor of collapse sources.

  5. Testing the Quick Seismic Event Locator and Magnitude Calculator (SSL_Calc) by Marsite Project Data Base

    Science.gov (United States)

    Tunc, Suleyman; Tunc, Berna; Caka, Deniz; Baris, Serif

    2016-04-01

    Locating and calculating size of the seismic events is quickly one of the most important and challenging issue in especially real time seismology. In this study, we developed a Matlab application to locate seismic events and calculate their magnitudes (Local Magnitude and empirical Moment Magnitude) using single station called SSL_Calc. This newly developed sSoftware has been tested on the all stations of the Marsite project "New Directions in Seismic Hazard Assessment through Focused Earth Observation in the Marmara Supersite-MARsite". SSL_Calc algorithm is suitable both for velocity and acceleration sensors. Data has to be in GCF (Güralp Compressed Format). Online or offline data can be selected in SCREAM software (belongs to Guralp Systems Limited) and transferred to SSL_Calc. To locate event P and S wave picks have to be marked by using SSL_Calc window manually. During magnitude calculation, instrument correction has been removed and converted to real displacement in millimeter. Then the displacement data is converted to Wood Anderson Seismometer output by using; Z=[0;0]; P=[-6.28+4.71j; -6.28-4.71j]; A0=[2080] parameters. For Local Magnitude calculation,; maximum displacement amplitude (A) and distance (dist) are used in formula (1) for distances up to 200km and formula (2) for more than 200km. ML=log10(A)-(-1.118-0.0647*dist+0.00071*dist2-3.39E-6*dist3+5.71e-9*dist4) (1) ML=log10(A)+(2.1173+0.0082*dist-0.0000059628*dist2) (2) Following Local Magnitude calculation, the programcode calculates two empiric Moment Magnitudes using formulas (3) Akkar et al. (2010) and (4) Ulusay et al. (2004). Mw=0.953* ML+0.422 (3) Mw=0.7768* ML+1.5921 (4) SSL_Calc is a software that is easy to implement and user friendly and offers practical solution to individual users to location of event and ML, Mw calculation.

  6. An unsupervised learning algorithm: application to the discrimination of seismic events and quarry blasts in the vicinity of Istanbul

    Directory of Open Access Journals (Sweden)

    H. S. Kuyuk

    2011-01-01

    Full Text Available The results of the application of an unsupervised learning (neural network approach comprising a Self Organizing Map (SOM, to distinguish micro-earthquakes from quarry blasts in the vicinity of Istanbul, Turkey, are presented and discussed. The SOM is constructed as a neural classifier and complementary reliability estimator to distinguish seismic events, and was employed for varying map sizes. Input parameters consisting of frequency and time domain data (complexity, spectral ratio, S/P wave amplitude peak ratio and origin time of events extracted from the vertical components of digital seismograms were estimated as discriminants for 179 (1.8 < Md < 3.0 local events. The results show that complexity and amplitude peak ratio parameters of the observed velocity seismogram may suffice for a reliable discrimination, while origin time and spectral ratio were found to be fuzzy and misleading classifiers for this problem. The SOM discussed here achieved a discrimination reliability that could be employed routinely in observatory practice; however, about 6% of all events were classified as ambiguous cases. This approach was developed independently for this particular classification, but it could be applied to different earthquake regions.

  7. Mud volcano monitoring and seismic events along the North Anatolian Fault (Sea of Marmara)

    Science.gov (United States)

    Javad Fallahi, Mohammad; Lupi, Matteo; Mazzini, Adriano; Polonia, Alina; D'Alessandro, Antonino; D'Anna, Giuseppe; Gasperini, Luca

    2017-04-01

    The Sea of Marmara, a pull-apart basin formed along the northern strand of the North Anatolian Fault (NAF) system, is considered a seismic gap, that will be filled in the next decades by a large magnitude (M>7) earthquake, close to the Istanbul Metropolitan area (12 million inhabitants). For this reason, several marine geological and geophysical studies have been carried out in this region, starting from the destructive 1999 Mw 7.4 Izmit earthquake, to gather information relative to seismogenic potential of major fault strands. Together with these studies, in the frame of EC projects (i.e., MarmESONET and Marsite, among others), an intensive program of long-term monitoring of seismogenic faults was carried out using seafloor observatories deployed during several expeditions led by Italian, French and Turkish groups. These expeditions included MARM2013, on board of the R/V Urania, of the Italian CNR, when four ocean bottom seismometers (OBS) were deployed in the central part of the Sea of Marmara, at depths between 550 and 1000 m. One of the main aims of the experiment was to assess the long-term seismic activity along an active segment of the NAF, which connects the central and the western basins (depocenters), where the principal deformation zone appears relatively narrow and almost purely strike-slip. The present study shows the results of processing and analysis of continuous data records from these OBS stations during 50 days. We were able to detect seismic signal produced by an active mud volcano located close to the NAF trace, from about 3 to 6 km of distance from the OBS stations. Additionally, we captured the May 24, 2014, Mw 6.9 strike-slip earthquake occurred in the northern Aegean Sea between Greece and Turkey, which caused serious damage on the Turkish island of Imbros and the cities of Edirne and Çanakkale, as well as on the Greek island of Lemnos. The earthquake nucleated on the westward continuation of the NAF system in the NE Aegean Sea, and was

  8. Networks of recurrent events, a theory of records, and an application to finding causal signatures in seismicity

    Science.gov (United States)

    Davidsen, Jörn; Grassberger, Peter; Paczuski, Maya

    2008-06-01

    We propose a method to search for signs of causal structure in spatiotemporal data making minimal a priori assumptions about the underlying dynamics. To this end, we generalize the elementary concept of recurrence for a point process in time to recurrent events in space and time. An event is defined to be a recurrence of any previous event if it is closer to it in space than all the intervening events. As such, each sequence of recurrences for a given event is a record breaking process. This definition provides a strictly data driven technique to search for structure. Defining events to be nodes, and linking each event to its recurrences, generates a network of recurrent events. Significant deviations in statistical properties of that network compared to networks arising from (acausal) random processes allows one to infer attributes of the causal dynamics that generate observable correlations in the patterns. We derive analytically a number of properties for the network of recurrent events composed by a random process in space and time. We extend the theory of records to treat not only the variable where records happen, but also time as continuous. In this way, we construct a fully symmetric theory of records leading to a number of results. Those analytic results are compared in detail to the properties of a network synthesized from time series of epicenter locations for earthquakes in Southern California. Significant disparities from the ensemble of acausal networks that can be plausibly attributed to the causal structure of seismicity are as follows. (1) Invariance of network statistics with the time span of the events considered. (2) The appearance of a fundamental length scale for recurrences, independent of the time span of the catalog, which is consistent with observations of the “rupture length.” (3) Hierarchy in the distances and times of subsequent recurrences. As expected, almost all of the statistical properties of a network constructed from a

  9. Investigating the Evolution of Southern California Salt Marshes: A Facies Model to Understand the Influence of Seismic Events on Environmental Resiliency and Sustainability

    Science.gov (United States)

    Aranda, A. N.; Carlin, J. A.; Rhodes, B. P.; Kirby, M.

    2016-02-01

    Only 10-20% of the US Pacific coast is estimated to be suitable for marsh development. In southern California specifically, marshes are disappearing ecosystems due to high population and urbanization. The future environmental impacts from climate change on these ecosystems are complicated not only by anthropogenic influences, but also by seismic activity in the region. In general, marsh evolution and response to seismic activity has yet to be fully explored in southern California. This study aims to develop a sediment facies model for salt marsh evolution in southern California by utilizing the salt marshes of the Seal Beach Wetlands (SBW). The SBW is an ideal location to develop the facies model because it straddles the active Newport-Inglewood Fault Zone. We collected sediment cores from the SBW that underwent a variety of sedimentological and geochemical analyses including grain size, X-Ray Fluorescence core scanning, magnetic susceptibility, and loss-on-ignition.. The results show a facies model consisting of sequences of marsh accretion punctuated by seismic events. These seismic events caused the marsh to subside, effectively re-setting marsh development from peat generation at a vegetated marsh state, to subtidal to intertidal mud deposition. The model also allowed us to qualify and quantify marsh recovery as inferred from event intensity, where what we perceived as more intense events resulted in more significant ecosystem disturbances and longer recovery times. Understanding this interplay between seismic activity and marsh development highlights the fragile nature of these ecosystems to climate change and sea level rise, as these stresses will only become amplified by seismic events.

  10. Real-time monitoring of seismicity and deformation during the Bárdarbunga rifting event and associated caldera subsidence

    Science.gov (United States)

    Jónsdóttir, Kristín; Ófeigsson, Benedikt; Vogfjörd, Kristín; Roberts, Matthew; Barsotti, Sara; Gudmundsson, Gunnar; Hensch, Martin; Bergsson, Bergur; Kjartansson, vilhjálmur; Erlendsson, Pálmi; Friðriksdóttir, Hildur; Hreinsdóttir, Sigrún; Guðmundsson, Magnús; Sigmundsson, Freysteinn; Árnadóttir, Thóra; Heimisson, Elías; Hjorleifsdóttir, Vala; Soring, Jón; Björnsson, Bogi; Oddsson, Björn

    2015-04-01

    We present a monitoring overview of a rifting event and associated caldera subsidence in a glaciated environment during the Bárðarbunga volcanic crisis. Following a slight increase in seismicity and a weak deformation signal, noticed a few months before the unrest by the SIL monitoring team, an intense seismic swarm began in the subglacial Bárðarbunga caldera on August 16 2014. During the following two weeks, a dyke intruded into the crust beneath the Vatnajökull ice cap, propagating 48 km from the caldera to the east-north-east and north of the glacier where an effusive eruption started in Holuhraun. The eruption is still ongoing at the time of writing and has become the largest eruption in over 200 years in Iceland. The dyke propagation was episodic with a variable rate and on several occasions low frequency seismic tremor was observed. Four ice cauldrons, manifestations of small subglacial eruptions, were detected. Soon after the swarm began the 7x11 km wide caldera started to subside and is still subsiding (although at slower rates) and has in total subsided over 60 meters. Unrest in subglacial volcanoes always calls for interdisciplinary efforts and teamwork plays a key role for efficient monitoring. Iceland has experienced six subglacial volcanic crises since modern digital monitoring started in the early 90s. With every crisis the monitoring capabilities, data interpretations, communication and information dissemination procedures have improved. The Civil Protection calls for a board of experts and scientists (Civil Protection Science Board, CPSB) to share their knowledge and provide up-to-date information on the current status of the volcano, the relevant hazards and most likely scenarios. The evolution of the rifting was monitored in real-time by the joint interpretation of seismic and cGPS data. The dyke propagation could be tracked and new, updated models of the dyke volume were presented at the CPSB meetings, often daily. In addition, deformation

  11. Analysis of rockburst and rockfall accidents in relation to class of stope support, regional support, energy of seismic events and mining layout

    CSIR Research Space (South Africa)

    Cichowicz, A

    1994-01-01

    Full Text Available This report discusses the assessment of safety risk and the analysis of Falls Of Ground (FOG) in mines due to seismic events and mining layout during the period of 1991-1992 on a single mine. The multivariate analysis was used to obtain a...

  12. Earthquake stress via event ratio levels: Application to the 2011 and 2016 Oklahoma seismic sequences

    Energy Technology Data Exchange (ETDEWEB)

    Walter, William R. [Lawrence Livermore National Laboratory, Livermore California USA; Yoo, Seung-Hoon [Weston Geophysical Corporation, Lexington Massachusetts USA; Mayeda, Kevin [University of California, Berkeley California USA; Gök, Rengin [Lawrence Livermore National Laboratory, Livermore California USA

    2017-04-14

    We develop a new methodology for determining earthquake stress drop and apparent stress values via spectral ratio asymptotic levels. With sufficient bandwidth, the stress ratio for a pair of events can be directly related to these low- and high-frequency levels. This avoids the need to assume a particular spectral model and derive stress drop from cubed corner frequency measures. The method can be applied to spectral ratios for any pair of closely related earthquakes and is particularly well suited for coda envelope methods that provide good azimuthally averaged, point-source measures. We apply the new method to the 2011 Prague and 2016 Pawnee earthquake sequences in Oklahoma. The sequences show stress scaling with size and depth, with the largest events having apparent stress levels near 1 MPa and smaller and/or shallower events having systematically lower stress values.

  13. Robust satellite techniques (RST for the thermal monitoring of earthquake prone areas: the case of Umbria-Marche October, 1997 seismic events

    Directory of Open Access Journals (Sweden)

    V. Tramutoli

    2008-06-01

    Full Text Available Several authors claim a space-time correlation between increases in Earth’s emitted Thermal Infra-Red (TIR radiation and earthquake occurrence. The main problems of such studies regard data analysis and interpretation, which are often done without a validation/confutation control. In this context, a robust data analysis technique (RST, i.e. Robust Satellite Techniques is proposed which permits a statistically based definition of TIR «anomaly » and uses a validation/confutation approach. This technique was already applied to satellite TIR surveys in seismic regions for about twenty earthquakes that occurred in the world. In this work RST is applied for the first time to a time sequence of seismic events. Nine years of Meteosat TIR observations have been analyzed to characterize the unperturbed TIR signal behaviour at specific observation times and locations. The main seismic events of the October 1997 Umbria-Marche sequence have been considered for validation, and relatively unperturbed periods (no earthquakes with Mb ? 4 were taken for confutation purposes. Positive time-space persistent TIR anomalies were observed during seismic periods, generally overlapping the principal tectonic lineaments of the region and sometimes focusing on the vicinity of the epicentre. No similar (in terms of relative intensity and space-time persistence TIR anomalies were detected during seismically unperturbed periods.

  14. Detecting erosion events in earth dam and levee passive seismic data with clustering

    NARCIS (Netherlands)

    Belcher, W.; Camp, T.; Krzhizhanovskaya, V.V.

    2015-01-01

    Geophysical sensor technologies can be used to understand the structural integrity of Earth Dams and Levees (EDLs). We are part of an interdisciplinary team researching techniques for the advancement of EDL health monitoring and the automatic detection of internal erosion events. We present results

  15. Social Media and E-Learning in Response to Seismic Events: Resilient Practices

    Science.gov (United States)

    Tull, Susan; Dabner, Nicki; Ayebi-Arthur, Kofi

    2017-01-01

    The motivation to adopt innovative communication and e-learning practices in education settings can be stimulated by events such as natural disasters. Education institutions in the Pacific Rim cannot avoid the likelihood of natural disasters that could close one or more buildings on a campus and affect their ability to continue current educational…

  16. Probability estimates of seismic event occurrence compared to health hazards - Forecasting Taipei's Earthquakes

    Science.gov (United States)

    Fung, D. C. N.; Wang, J. P.; Chang, S. H.; Chang, S. C.

    2014-12-01

    Using a revised statistical model built on past seismic probability models, the probability of different magnitude earthquakes occurring within variable timespans can be estimated. The revised model is based on Poisson distribution and includes the use of best-estimate values of the probability distribution of different magnitude earthquakes recurring from a fault from literature sources. Our study aims to apply this model to the Taipei metropolitan area with a population of 7 million, which lies in the Taipei Basin and is bounded by two normal faults: the Sanchaio and Taipei faults. The Sanchaio fault is suggested to be responsible for previous large magnitude earthquakes, such as the 1694 magnitude 7 earthquake in northwestern Taipei (Cheng et. al., 2010). Based on a magnitude 7 earthquake return period of 543 years, the model predicts the occurrence of a magnitude 7 earthquake within 20 years at 1.81%, within 79 years at 6.77% and within 300 years at 21.22%. These estimates increase significantly when considering a magnitude 6 earthquake; the chance of one occurring within the next 20 years is estimated to be 3.61%, 79 years at 13.54% and 300 years at 42.45%. The 79 year period represents the average lifespan of the Taiwan population. In contrast, based on data from 2013, the probability of Taiwan residents experiencing heart disease or malignant neoplasm is 11.5% and 29%. The inference of this study is that the calculated risk that the Taipei population is at from a potentially damaging magnitude 6 or greater earthquake occurring within their lifetime is just as great as of suffering from a heart attack or other health ailments.

  17. 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

  18. The forecast of mining-induced seismicity and the consequent risk of damage to the excavation in the area of seismic event

    Directory of Open Access Journals (Sweden)

    Jan Drzewiecki

    2017-01-01

    Full Text Available The Central Mining Institute has developed a method for forecasting the amount of seismic energy created by tremors induced by mining operations. The results of geophysical measurements of S wave velocity anomalies in a rock mass or the results of analytic calculations of the values of pressure on the horizon of the elastic layers are used in the process of calculating the energy. The calculation program which has been developed and adopted has been modified over recent years and it now enables not only the prediction of the energy of dynamic phenomena induced by mining but also the forecasting of the devastating range of seismic shock. The results obtained from this calculation, usually presented in a more readable graphic form, are useful for the macroscopic evaluation of locations that are potential sources of seismic energy. Forecasting of the maximum energy of seismic shock without prior knowledge of the location of the shock's source, does not allow shock attenuation that results from, for example, a distance of tremor source from the excavation which will be affected by seismic energy, to be taken into consideration. The phenomena of energy dissipation, which is taken into account in the forecasts, create a new quality of assessment of threat to the excavation. The paper presents the principle of a method of forecasting the seismic energy of a shock and the risk of damage to the excavation as a result of the impact of its energy wave. The solution assumes that the source of the energy shock is a resilient layer in which the sum of the gravitational stresses, resulting from natural disturbances and those induced by the conducted or planned mining exploitation, is estimated. The proposed solution assumes a spherical model for the tremor source, for which seismic energy is forecasted as a function of the longwall advance and the elementary value of seismic energy destroying the excavation. Subsequently, the following are calculated for the

  19. Use of waveform similarity to define planes of mining-induced seismic events

    CSIR Research Space (South Africa)

    Spottiswoode, SM

    1998-04-15

    Full Text Available ; Deichmann and Garcia- Fernandez, 1992). Groups of doublets can be called multiplets (Fremont and Malone, 1987; Moriya et al., 1996). In this paper we extend the doublet relative location procedure and introduce multiplet relocation using arrival... planes in- ferred from an aftershock sequence. Fehler et al. (1987) proposed the ?three-point method? to infer the planes of events locations. This method assumes that the earthquakes occur over pre-existing planes (fault planes) and defines each plane...

  20. Study of typical space wave-particle coupling events possibly related with seismic activity

    CERN Document Server

    Zhang, Zhenxia; Shen, Xuhui; Li, Xinqiao; Wu, Shugui

    2014-01-01

    Based on the DEMETER satellite, we found two space wave-particle coupling events during February 2010 taking place in the range of McIlwain parameter $L$($1.27\\sim1.37$). There are strong spatial and temporal correlation between the particle bursts(PBs) and the electromagnetic disturbances of the coupling events. The two PBs show different energy spectrum characteristics, while the corresponding electromagnetic disturbances concentrated on different frequencies range. In agreement with the prediction of the theory of wave-particle interaction, we conclude that the two wave-particle interactions can be probably explained as following: one is electron dominant precipitation with energy of $0.09\\sim0.2$ MeV induced by VLF electromagnetic wave with the frequency of $14\\sim20$ kHz, and another is proton dominant precipitation with energy of $0.65\\sim2.85$ MeV induced by VLF electromagnetic wave with the frequency of $\\le 100$ Hz. For the first time, those particle bursts origin, from electron or proton detected by...

  1. A multi-station matched filter and coherent network processing approach to the automatic detection and relative location of seismic events

    Science.gov (United States)

    Gibbons, Steven J.; Näsholm, Sven Peter; Kværna, Tormod

    2014-05-01

    Correlation detectors facilitate seismic monitoring in the near vicinity of previously observed events at far lower detection thresholds than are possible using the methods applied in most existing processing pipelines. The use of seismic arrays has been demonstrated to be highly beneficial in pressing down the detection threshold, due to superior noise suppression, and also in eliminating vast numbers of false alarms by performing array processing on the multi-channel output of the correlation detectors. This last property means that it is highly desirable to run continuous detectors for sites of repeating seismic events on a single-array basis for many arrays across a global network. Spurious detections for a given signal template on a single array can however still occur when an unrelated wavefront crosses the array from a very similar direction to that of the master event wavefront. We present an algorithm which scans automatically the output from multiple stations - both array and 3-component - for coherence between the individual station correlator outputs that is consistent with a disturbance in the vicinity of the master event. The procedure results in a categorical rejection of an event hypothesis in the absence of support from stations other than the one generating the trigger and provides a fully automatic relative event location estimate when patterns in the correlation detector outputs are found to be consistent with a common event. This coherence-based approach removes the need to make explicit measurements of the time-differences for single stations and this eliminates a potential source of error. The method is demonstrated for the North Korea nuclear test site and the relative event location estimates obtained for the 2006, 2009, and 2013 events are compared with previous estimates from different station configurations.

  2. Tree-ring dated landslide movements and seismic events in southwestern Montana, USA

    Science.gov (United States)

    Carrara, Paul E.; O'Neill, J. Michael

    2010-01-01

    Because many tree species can live for several centuries or longer (Brown 1996), tree-ring analysis can be a valuable tool to date geomorphic events such as landslides, earthquakes, and avalanches in regions lacking long historical records. Typically, a catastrophic landslide will destroy all trees on the landslide, but trees on slower moving landslides may survive. For example, the Slumgullion earthflow, in southwestern Colorado, moves 0.5–5.5 m annually, yet is covered by aspen (Populus tremuloides) and conifers (Baum and Fleming 1996). Trees that survive such movements undoubtedly suffer damage, such as topping, tilting, impact, or root breakage. This damage is commonly recorded in the tree-ring record and analysis of this record can be used to reconstruct past landslide activity.

  3. Repeating LP events and increases in high-frequency seismic energy preceding the December 1999 eruption of the quiescently active Telica Volcano, Nicaragua

    Science.gov (United States)

    Rodgers, M.; Roman, D. C.; Geirsson, H.; Lafemina, P.; Muñoz, A.; Guzman, C.; Tenorio, V.

    2010-12-01

    Telica volcano, Nicaragua, is a ‘quiescently active’ basaltic andesite stratovolcano located in the Central American volcanic front. A high rate of long-period (LP) seismicity has been recorded at Telica since the installation of a single vertical-component 1 Hz seismic sensor (TELN) near its summit in 1993 by the Instituto Nicaragüense de Estudios Territoriales (INETER). Due to the continuously high rate of LPs at Telica, traditional methods of forecasting volcanic activity may not be applicable; therefore an understanding of the nature of precursory changes in Telica’s seismicity is necessary to accurately forecast future volcanic activity. A VEI 2 eruption of Telica occurred on the 29th December 1999, preceded by a series of small explosions between the 3rd-15th October 1999. Here we analyse an eight-month period of seismicity bracketing this activity, in an attempt to identify precursory changes with respect to background seismicity. Between August 1999 and March 2000 over 18,000 seismic events were recorded on TELN. We first calculated the dominant frequencies (i.e. frequency with dominant spectral energy) for all events recorded during this period. A time series of the dominant event frequencies between August 1999 and March 2000 shows a significant increase in the number of high frequency (> 5 Hz) events and, in LP events, a shift in the two dominant spectral energy peaks from 2 Hz and 4 Hz to 2 Hz and 3 Hz in the month before the October 1999 explosions. Next, we selected six representative eight-day periods, three from before the explosions and three from after, for multiplet analysis using waveform cross-correlation. Multiplet analysis of the six selected time periods reveal significant changes in behaviour. In period 1 (more than one month before the explosions) events are poorly correlated. In periods 2 and 3 (less than one month before the explosions) we identified several unique families of LP events, each having high cross-correlation values

  4. Efficient Integration of Old and New Research Tools for Automating the Identification and Analysis of Seismic Reference Events

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Robert; Rivers, Wilmer

    2005-01-25

    any single computer program for seismic data analysis will not have all the capabilities needed to study reference events, since hese detailed studies will be highly specialized. It may be necessary to develop and test new algorithms, and then these special ;odes must be integrated with existing software to use their conventional data-processing routines. We have investigated two neans of establishing communications between the legacy and new codes: CORBA and XML/SOAP Web services. We have nvestigated making new Java code communicate with a legacy C-language program, geotool, running under Linux. Both methods vere successful, but both were difficult to implement. C programs on UNIX/Linux are poorly supported for Web services, compared vith the Java and .NET languages and platforms. Easier-to-use middleware will be required for scientists to construct distributed applications as easily as stand-alone ones. Considerable difficulty was encountered in modifying geotool, and this problem shows he need to use component-based user interfaces instead of large C-language codes where changes to one part of the program nay introduce side effects into other parts. We have nevertheless made bug fixes and enhancements to that legacy program, but t remains difficult to expand it through communications with external software.

  5. MULTITEMPORAL 3D MODELLING FOR CULTURAL HERITAGE EMERGENCY DURING SEISMIC EVENTS: DAMAGE ASSESMENT OF S. AGOSTINO CHURCH IN AMATRICE (RI

    Directory of Open Access Journals (Sweden)

    F. Chiabrando

    2017-05-01

    Full Text Available One of the challenging purposes that must be undertaken by applied geomatics, is the need of monitoring by documenting continuously over time the evolution of urban spaces. Nowadays, this is a subject of great interest and study, mainly in case of sudden emergency events that implicate urban areas and specific historical buildings of our heritage. The newest Geomatics technique solutions must enable the demands of damage documentation, risk assessment, management and data sharing as efficiently as possible, in relation to the danger condition, to the accessibility constraints of areas and to the tight deadlines needs. In August 24th 2016, the first earthquake hit the area of central Italy with a magnitude of 6.0; since then, the earth never stop shaking in a wide area in the middle of Italy. On 26th and 30th of October, two other big seismic events were recorded (magnitude 5.9 and 6.5 and the already damaged built heritage were struck again. Since the beginning of the emergency all the available resources (human and material were deployed and the world of researchers is trying to furnish an effective contribute as well. Politecnico di Torino, in coordination with the national institutions, is deploying people, expertise and resources. The geomatics research group and the connected Disaster Recovery team (DIRECT - http://areeweb.polito.it/direct/ is part of this process and is working in deep contact and collaboration with the Remotely Piloted Aircraft Systems (RPAS group of the Italian Firefighter. Starting from the first earthquake the late medieval religious complex of S. Agostino has been carefully monitored and detected, using a multi-perspective oblique imagery strategy with the aim to achieve 3D aerial and terrestrial models, in a multi-temporal perspective concerning three different time situation.

  6. Multitemporal 3d Modelling for Cultural Heritage Emergency during Seismic Events: Damage Assesment of S. Agostino Church in Amatrice (ri)

    Science.gov (United States)

    Chiabrando, F.; Di Lolli, A.; Patrucco, G.; Spanò, A.; Sammartano, G.; Teppati Losè, L.

    2017-05-01

    One of the challenging purposes that must be undertaken by applied geomatics, is the need of monitoring by documenting continuously over time the evolution of urban spaces. Nowadays, this is a subject of great interest and study, mainly in case of sudden emergency events that implicate urban areas and specific historical buildings of our heritage. The newest Geomatics technique solutions must enable the demands of damage documentation, risk assessment, management and data sharing as efficiently as possible, in relation to the danger condition, to the accessibility constraints of areas and to the tight deadlines needs. In August 24th 2016, the first earthquake hit the area of central Italy with a magnitude of 6.0; since then, the earth never stop shaking in a wide area in the middle of Italy. On 26th and 30th of October, two other big seismic events were recorded (magnitude 5.9 and 6.5) and the already damaged built heritage were struck again. Since the beginning of the emergency all the available resources (human and material) were deployed and the world of researchers is trying to furnish an effective contribute as well. Politecnico di Torino, in coordination with the national institutions, is deploying people, expertise and resources. The geomatics research group and the connected Disaster Recovery team (DIRECT - http://areeweb.polito.it/direct/) is part of this process and is working in deep contact and collaboration with the Remotely Piloted Aircraft Systems (RPAS) group of the Italian Firefighter. Starting from the first earthquake the late medieval religious complex of S. Agostino has been carefully monitored and detected, using a multi-perspective oblique imagery strategy with the aim to achieve 3D aerial and terrestrial models, in a multi-temporal perspective concerning three different time situation.

  7. A meteor shockwave event recorded at seismic and infrasound stations in northern Taiwan

    Science.gov (United States)

    Kumar, Utpal; Chao, Benjamin F.; Hsieh, Yikai; Chang, Emmy T. Y.

    2017-12-01

    Three mysterious explosion sounds were heard in the coastal towns of Tamsui, west of Taipei in northern Taiwan, in the early evening of December 5, 2013. The event left clear signals that are identified in the recordings of 12 regional seismometers and 3 infrasound sensors and processed by means of travel time analysis. The apparent velocity of 330 m/s of the signals confirms that the energy transmission was through the atmosphere, and the characteristics of the waveforms suggest the meteor-generated shockwaves. We use the graphical method as well as the Genetic Algorithm optimization approach to constrain the trajectory of the meteor and to locate its projected intercept with the ground—(25.33 N, 121.26 E), approximately 20 km off the coast of Tamsui. The trajectory has azimuth (measured from north in a map view in the clockwise direction) of 303° and (near-vertical) elevation angle of 70°. From the observed period of 1.3 s at the maximum amplitude of the infrasound signal, we estimate by conventional scaling law that the meteor in question had impact energy on the order of 5 × 1010 J (equivalent to an earthquake of local magnitude 4) or roughly a size of 0.5 m across.

  8. A fast and robust method for moment tensor and depth determination of shallow seismic events in CTBT related studies.

    Science.gov (United States)

    Baker, Ben; Stachnik, Joshua; Rozhkov, Mikhail

    2017-04-01

    International Data Center is required to conduct expert technical analysis and special studies to improve event parameters and assist State Parties in identifying the source of specific event according to the protocol to the Protocol to the Comprehensive Nuclear Test Ban Treaty. Determination of seismic event source mechanism and its depth is closely related to these tasks. It is typically done through a strategic linearized inversion of the waveforms for a complete or subset of source parameters, or similarly defined grid search through precomputed Greens Functions created for particular source models. In this presentation we demonstrate preliminary results obtained with the latter approach from an improved software design. In this development we tried to be compliant with different modes of CTBT monitoring regime and cover wide range of source-receiver distances (regional to teleseismic), resolve shallow source depths, provide full moment tensor solution based on body and surface waves recordings, be fast to satisfy both on-demand studies and automatic processing and properly incorporate observed waveforms and any uncertainties a priori as well as accurately estimate posteriori uncertainties. Posterior distributions of moment tensor parameters show narrow peaks where a significant number of reliable surface wave observations are available. For earthquake examples, fault orientation (strike, dip, and rake) posterior distributions also provide results consistent with published catalogues. Inclusion of observations on horizontal components will provide further constraints. In addition, the calculation of teleseismic P wave Green's Functions are improved through prior analysis to determine an appropriate attenuation parameter for each source-receiver path. Implemented HDF5 based Green's Functions pre-packaging allows much greater flexibility in utilizing different software packages and methods for computation. Further additions will have the rapid use of Instaseis

  9. Peakmatch - a New Program for Large-Scale Seismic Multiplet Analysis and Event Classification: An Application to Soufrière Hills Volcano, Montserrat.

    Science.gov (United States)

    Rodgers, M.; Smith, P.; Pyle, D. M.; Mather, T. A.; Rodgers, S.

    2014-12-01

    The large amounts of data generated by volcano observatories, especially during volcanic crises, can present a challenge for rapid analysis of changing event behaviour. Statistical analysis of seismic events, e.g. spectral analysis and identification of waveform families (i.e. multiplet analysis) can be useful tools in characterising the seismicity and can provide another layer of information for volcano observatories. Additionally, multiplet analysis of existing data from key eruptions can reveal patterns of behaviour that are not evident from individual event metrics (e.g. locations, amplitudes, frequency content etc.). However, large scale multiplet analysis has previously been hindered by the computational limitations associated with cross-correlation of large data sets. Event classification remains crucial to volcano monitoring and to retrospective analysis of key eruption data, but such methods are often not straightforward to implement. We present a program, PEAKMATCH, which can be used for spectral and multiplet analysis of large data sets, and can be used for simple automatic classification of volcanic events. Our optimised cross-correlation approach can efficiently handle the cross-correlation of hundreds of thousands of events making large-scale multiplet studies a reality. Much of the crucial information for classifying an event lies in the frequency domain and by using spectral ratios and cluster analysis we are able to automatically classify events without an extensive training period. We apply our method to seismic data from Soufrière Hills Volcano, Montserrat from the end of the last extrusion period in February 2010 until January 2014 to characterise the multiplet behaviour during an extended period of quiescence. We observe notable changes in multiplet behaviour surrounding the period of ash venting in March 2012.

  10. System and method for generating micro-seismic events and characterizing properties of a medium with non-linear acoustic interactions

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Cung Khac; Nihei, Kurt; Johnson, Paul A.; Guyer, Robert; Ten Cate, James A.; Le Bas, Pierre-Yves; Larmat, Carene S.

    2015-12-29

    A method and system includes generating a first coded acoustic signal including pulses each having a modulated signal at a central frequency; and a second coded acoustic signal each pulse of which includes a modulated signal a central frequency of which is a fraction d of the central frequency of the modulated signal for the corresponding pulse in the first plurality of pulses. A receiver detects a third signal generated by a non-linear mixing process in the mixing zone and the signal is processed to extract the third signal to obtain an emulated micro-seismic event signal occurring at the mixing zone; and to characterize properties of the medium or creating a 3D image of the properties of the medium, or both, based on the emulated micro-seismic event signal.

  11. On the predictability of volcano-tectonic events by low frequency seismic noise analysis at Teide-Pico Viejo volcanic complex, Canary Islands

    Directory of Open Access Journals (Sweden)

    M. Tárraga

    2006-01-01

    Full Text Available The island of Tenerife (Canary Islands, Spain, is showing possible signs of reawakening after its last basaltic strombolian eruption, dated 1909 at Chinyero. The main concern relates to the central active volcanic complex Teide - Pico Viejo, which poses serious hazards to the properties and population of the island of Tenerife (Canary Islands, Spain, and which has erupted several times during the last 5000 years, including a subplinian phonolitic eruption (Montaña Blanca about 2000 years ago. In this paper we show the presence of low frequency seismic noise which possibly includes tremor of volcanic origin and we investigate the feasibility of using it to forecast, via the material failure forecast method, the time of occurrence of discrete events that could be called Volcano-Tectonic or simply Tectonic (i.e. non volcanic on the basis of their relationship to volcanic activity. In order to avoid subjectivity in the forecast procedure, an automatic program has been developed to generate forecasts, validated by Bayes theorem. A parameter called 'forecast gain' measures (and for the first time quantitatively what is gained in probabilistic terms by applying the (automatic failure forecast method. The clear correlation between the obtained forecasts and the occurrence of (Volcano-Tectonic seismic events - a clear indication of a relationship between the continuous seismic noise and the discrete seismic events - is the explanation for the high value of this 'forecast gain' in both 2004 and 2005 and an indication that the events are Volcano-Tectonic rather than purely Tectonic.

  12. The ear, the eye, earthquakes and feature selection: listening to automatically generated seismic bulletins for clues as to the differences between true and false events.

    Science.gov (United States)

    Kuzma, H. A.; Arehart, E.; Louie, J. N.; Witzleben, J. L.

    2012-04-01

    Listening to the waveforms generated by earthquakes is not new. The recordings of seismometers have been sped up and played to generations of introductory seismology students, published on educational websites and even included in the occasional symphony. The modern twist on earthquakes as music is an interest in using state-of-the-art computer algorithms for seismic data processing and evaluation. Algorithms such as such as Hidden Markov Models, Bayesian Network models and Support Vector Machines have been highly developed for applications in speech recognition, and might also be adapted for automatic seismic data analysis. Over the last three years, the International Data Centre (IDC) of the Comprehensive Test Ban Treaty Organization (CTBTO) has supported an effort to apply computer learning and data mining algorithms to IDC data processing, particularly to the problem of weeding through automatically generated event bulletins to find events which are non-physical and would otherwise have to be eliminated by the hand of highly trained human analysts. Analysts are able to evaluate events, distinguish between phases, pick new phases and build new events by looking at waveforms displayed on a computer screen. Human ears, however, are much better suited to waveform processing than are the eyes. Our hypothesis is that combining an auditory representation of seismic events with visual waveforms would reduce the time it takes to train an analyst and the time they need to evaluate an event. Since it takes almost two years for a person of extraordinary diligence to become a professional analyst and IDC contracts are limited to seven years by Treaty, faster training would significantly improve IDC operations. Furthermore, once a person learns to distinguish between true and false events by ear, various forms of audio compression can be applied to the data. The compression scheme which yields the smallest data set in which relevant signals can still be heard is likely an

  13. Novel ST-MUSIC-based spectral analysis for detection of ULF geomagnetic signals anomalies associated with seismic events in Mexico

    Directory of Open Access Journals (Sweden)

    Omar Chavez

    2016-05-01

    Full Text Available Recently, the analysis of ultra-low-frequency (ULF geomagnetic signals in order to detect seismic anomalies has been reported in several works. Yet, they, although having promising results, present problems for their detection since these anomalies are generally too much weak and embedded in high noise levels. In this work, a short-time multiple signal classification (ST-MUSIC, which is a technique with high-frequency resolution and noise immunity, is proposed for the detection of seismic anomalies in the ULF geomagnetic signals. Besides, the energy (E of geomagnetic signals processed by ST-MUSIC is also presented as a complementary parameter to measure the fluctuations between seismic activity and seismic calm period. The usefulness and effectiveness of the proposal are demonstrated through the analysis of a synthetic signal and five real signals with earthquakes. The analysed ULF geomagnetic signals have been obtained using a tri-axial fluxgate magnetometer at the Juriquilla station, which is localized in Queretaro, Mexico (geographic coordinates: longitude 100.45° E and latitude 20.70° N. The results obtained show the detection of seismic perturbations before, during, and after the main shock, making the proposal a suitable tool for detecting seismic precursors.

  14. Improving Seismic Event Characterisation

    Science.gov (United States)

    1996-07-22

    to first order across the transition from an optical path to a diffracted path ( dashed vertical lines), It is possible to show, analytically that...tiigaphlic (and oither) mlodels (t1eI dashed ). 4 -TI 7-o a -a 04-8012 160 Epicentral distance (dog) F~igure, 7: 11lcalizationis or models of lateral slicai...8217 l op 500t kill ’Ify p I I: 11) I it I~ j 1it t II "ooIw [()I. dieta tiloall IIo dtipi 11diwid-l U9 U SSS AI PHEM 4% 8% 12% 1J50 - _ LU T130 -1 A- 0

  15. Coseismic and aseismic deformations associated with mining-induced seismic events located in deep level mines in South Africa

    CSIR Research Space (South Africa)

    Milev, A

    2013-10-01

    Full Text Available Two underground sites in a deep level gold mine in South Africa were instrumented by the Council for Scientific and Industrial Research (CSIR) with tilt meters and seismic monitors. One of the sites was also instrumented by Japanese...

  16. Results from the temporary installation of a small aperture seismic arrayin the Central Apenninesand its merits for local event detectionand location capabilities

    Directory of Open Access Journals (Sweden)

    E. Boschi

    2004-06-01

    Full Text Available In order to evaluate the detection and localisation improvement of a small aperture array in the Northern Apennines, we installed an irregularly spaced test configuration in the vicinity of Città di Castello (CDC for a period of two weeks. The experimental array consisted of nine 3-component stations with inter-station distances between 150 m and 2200 m. Seismic data were digitised at 125 Hz and telemetered to a mobile acquisition, processing and storage centre. The data could only be recorded in trigger mode. The peculiarity of the test array installation was the exclusive use of 3-component sensors at all array sites, which also allowed beamforming for S-phases on the horizontal components. Since the altitudes of the single array sites differed considerably among each other, for f-k analysis and beamforming an elevation correction was included. During the two weeks of operation about 20 local earthquakes with magnitudes ML<2.6, 1 regional, and several teleseismic events were recorded. In addition to these events, the array occasionally triggered on coherent noise-signals generated by local industrial activity. The data analysis was performed by means of f-k analysis and beamforming, providing wavenumber characteristics of the incident plane wave. Typical apparent velocities were determined to be 4.8 km/s and 6 km/s for Pg-phases and ~10 km/s for Pn-phases. We observed local seismic events, which occurred just beneath the array. In these cases wavefronts with unusual high apparent velocities, similar to those found for the Pn-phase, were observed. Since no continuously recorded array data were available, we extrapolated the lower detection magnitude threshold as a result of the SNR improvement due to array beamforming. Compared to the actual detection threshold of MT ~1.6 reached by the national seismic network in this area, a nine element array would improve this value up to MT ~ 0.8.

  17. Lessons from M 7.2 Seismic Event and How to Preserve Awareness Forty Years Later: The Case of the Vrancea, Romania, March 4, 1977 Earthquake

    Science.gov (United States)

    Craifaleanu, Iolanda-Gabriela; Georgescu, Emil-Sever; Dragomir, Claudiu-Sorin

    2016-10-01

    Almost four decades after the MG-R = 7.2 (Mw =7.4) catastrophic earthquake of March 4, 1977 hit Romania, the population fears a new strong earthquake; however, awareness on preparedness and mitigation measures is rather low. As the last Mw > 6 has occurred in 1990, there is an increasing percentage of young population that has not yet witnessed a strong earthquake, and which has a rather fuzzy representation of urban and geological earthquake effects. After each strong seismic event in the past, due to its specific attributions, the National Institute for Building Research, INCERC, collected a considerable amount of information about the earthquake effects on built environment and lifelines, geological effects etc. To this, information from various documentary sources about damage caused by historic earthquakes was added by the institute's specialists. Stored today in the archives of the National Institute for Research and Development in Construction, Urban Planning and Sustainable Spatial Development, “URBAN-INCERC”, INCERC Bucharest Branch, this information is invaluable today for evaluating the present and future seismic risk of the country. Nonetheless, it could represent an essential educational resource for university students and young professionals in the field of civil engineering, seismology, geology, economy, sociology, history etc. and for raising population awareness on seismic risk mitigation measures. The paper presents new approaches for the dissemination and re-valuation of the March 4, 1977 earthquake data, from the perspective of present scientific knowledge.

  18. Possibility of prediction of strong seismic events in the Middle Odra Fault Zone based on variations of kinematic activity of the Świebodzice Depression

    Science.gov (United States)

    Kaczorowski, Marek; Kasza, Damian; Zdunek, Ryszard; Wronowski, Roman; Szczerbowski, Zbigniew

    2017-04-01

    Książ Geodynamic Laboratory of Space Research Centre is located in the Świebodzice Depression unit. The laboratory was built inside underground corridors made in the castle hill about 50 m below surface. The main instruments which provide us most of information about tectonic activity of Świebodzice Depression are two long water-tubes tiltmeters 65 and 92 meters long (WT). The WT are situated on several rocky blocks which motions provided tectonic signals to WT. The instruments register numerous irregularly occurred epochs of water levels variations in hydrodynamic systems of magnitudes exceeding tidal signals dozens or so times. These observations are interpreted as result of tiltings of foundation and vertical motions of rock blocks. Signals of tiltings of foundation and vertical motions are superposed by the WT registration system. The resultant signals from four channels of WT were defined by us as tectonic activity functions of the massif. Variations of the tectonic activity functions as well as their first derivatives were compared with the seismic activity in Fore-Sudetic Monocline. We found correlation in time and amplitudes domains between extremes and inflection points of the first derivative of the tectonic activity function and the seismic events in the Middle Odra Fault Zone of the Fore-Sudetic Monocline. High correlation concerns only the strong earthquakes the energies of which were larger than 4 MJ. Almost all the high energy seismic events from 2005 to 2015 took place in surroundings of minima, maxima or inflection points of tectonic activity functions when first derivatives were close to zero. In the epochs of large absolute values of amplitudes of first derivatives i.e. during high tectonic activity of Świebodzice Depression, the strong energy earthquakes never happened. The observation shows that the origin of the low and high energy earthquakes is different. The high energy earthquakes are produced by natural tectonic activity, while the

  19. Seismic hazard in low slip rate crustal faults, estimating the characteristic event and the most hazardous zone: study case San Ramón Fault, in southern Andes

    Science.gov (United States)

    Estay, Nicolás P.; Yáñez, Gonzalo; Carretier, Sebastien; Lira, Elias; Maringue, José

    2016-11-01

    Crustal faults located close to cities may induce catastrophic damages. When recurrence times are in the range of 1000-10 000 or higher, actions to mitigate the effects of the associated earthquake are hampered by the lack of a full seismic record, and in many cases, also of geological evidences. In order to characterize the fault behavior and its effects, we propose three different already-developed time-integration methodologies to define the most likely scenarios of rupture, and then to quantify the hazard with an empirical equation of peak ground acceleration (PGA). We consider the following methodologies: (1) stream gradient and (2) sinuosity indexes to estimate fault-related topographic effects, and (3) gravity profiles across the fault to identify the fault scarp in the basement. We chose the San Ramón Fault on which to apply these methodologies. It is a ˜ 30 km N-S trending fault with a low slip rate (0.1-0.5 mm yr-1) and an approximated recurrence of 9000 years. It is located in the foothills of the Andes near the large city of Santiago, the capital of Chile (> 6 000 000 inhabitants). Along the fault trace we define four segments, with a mean length of ˜ 10 km, which probably become active independently. We tested the present-day seismic activity by deploying a local seismological network for 1 year, finding five events that are spatially related to the fault. In addition, fault geometry along the most evident scarp was imaged in terms of its electrical resistivity response by a high resolution TEM (transient electromagnetic) profile. Seismic event distribution and TEM imaging allowed the constraint of the fault dip angle (˜ 65°) and its capacity to break into the surface. Using the empirical equation of Chiou and Youngs (2014) for crustal faults and considering the characteristic seismic event (thrust high-angle fault, ˜ 10 km, Mw = 6.2-6.7), we estimate the acceleration distribution in Santiago and the hazardous zones. City domains that are under

  20. WOOD-BASED SOLUTIONS TO IMPROVE QUALITY AND SAFETY AGAINST SEISMIC EVENTS IN CONSERVATION OF HISTORICAL BUILDINGS

    Directory of Open Access Journals (Sweden)

    Elena Ongaretto

    2016-03-01

    Full Text Available Historical buildings can be highly vulnerable to earthquakes if in-plane strength and stiffness of floors and roofs are not sufficient to limit out-of-plane deformation of walls and to transmit the seismic forces among walls efficiently. In fact, floors and roofs in existing masonry buildings are normally realized with timber beams, purlins and a single layer of timber boards, and their in-plane stiffness can be limited when subjected to shear forces. Various retrofitting techniques are available, whose effectiveness can be very different and not easily predictable theoretically. In this paper, the behavior of different strengthening criteria for historical buildings, involving the use of wood and wood based products, is illustrated and critically discussed. Code provisions, design rules and calculation methods for strengthening interventions are described. In-plane behavior of floor and roof structures and their interaction and connection to the seismic resistant wall systems are considered. Finally, a case study of restoration intervention on a historic barn is presented, which was damaged during the 2012 earthquake in Emilia. The illustration is focused on the improvement of the whole safety of the construction by means of specifically designed interventions on the wooden roof.

  1. Seismic Imaging and Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Lianjie [Los Alamos National Laboratory

    2012-07-09

    I give an overview of LANL's capability in seismic imaging and monitoring. I present some seismic imaging and monitoring results, including imaging of complex structures, subsalt imaging of Gulf of Mexico, fault/fracture zone imaging for geothermal exploration at the Jemez pueblo, time-lapse imaging of a walkway vertical seismic profiling data for monitoring CO{sub 2} inject at SACROC, and microseismic event locations for monitoring CO{sub 2} injection at Aneth. These examples demonstrate LANL's high-resolution and high-fidelity seismic imaging and monitoring capabilities.

  2. Interpretation of seismic section by acoustic modeling. Study of large amplitude events; Hadoba modeling ni yoru jishin tansa danmen no kaishaku. Kyoshinhaba event ni taisuru kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Tamagawa, T.; Matsuoka, T.; Sato, T. [Japan Petroleum Exploration Corp., Tokyo (Japan); Minegishi, M.; Tsuru, T. [Japan National Oil Corp., Tokyo (Japan)

    1996-05-01

    A large amplitude event difficult to interpret was discovered in the overlap section in offset data beyond 10km targeting at deep structures, and the event was examined. A wave field modeling was carried out by use of a simplified synclinal structure model because it had been estimated that the large amplitude event had something to do with a synclinal structure. A pseudospectral program was used for modeling the wave field on the assumption that the synclinal structure model would be an acoustic body and that the surface would contain free boundaries and multiple reflection. It was found as the result that a discontinuous large amplitude event is mapped out in the synclinal part of the overlap section when a far trace is applied beyond the structure during a CMP overlap process. This can be attributed to the concentration of energy produced by multiple reflection in the synclinal part and by the reflection waves beyond the critical angle. Accordingly, it is possible that phenomena similar to those encountered in the modeling process are emerging during actual observation. 2 refs., 8 figs.

  3. Effects of a significant New Madrid Seismic Zone event on oil and natural gas pipelines and their cascading effects to critical infrastructures

    Science.gov (United States)

    Fields, Damon E.

    Critical Infrastructure Protection (CIP) is a construct that relates preparedness and responsiveness to natural or man-made disasters that involve vulnerable assets deemed essential for the functioning of our economy and society. Infrastructure systems (power grids, bridges, airports, etc.) are vulnerable to disastrous types of events--natural or man-made. Failures of these systems can have devastating effects on communities and entire regions. CIP relates our willingness, ability, and capability to defend, mitigate, and re-constitute those assets that succumb to disasters affecting one or more infrastructure sectors. This qualitative research utilized ethnography and employed interviews with subject matter experts (SMEs) from various fields of study regarding CIP with respect to oil and natural gas pipelines in the New Madrid Seismic Zone. The study focused on the research question: What can be done to mitigate vulnerabilities in the oil and natural gas infrastructures, along with the potential cascading effects to interdependent systems, associated with a New Madrid fault event? The researcher also analyzed National Level Exercises (NLE) and real world events, and associated After Action Reports (AAR) and Lessons Learned (LL) in order to place a holistic lens across all infrastructures and their dependencies and interdependencies. Three main themes related to the research question emerged: (a) preparedness, (b) mitigation, and (c) impacts. These themes comprised several dimensions: (a) redundancy, (b) node hardening, (c) education, (d) infrastructure damage, (e) cascading effects, (f) interdependencies, (g) exercises, and (h) earthquake readiness. As themes and dimensions are analyzed, they are considered against findings in AARs and LL from previous real world events and large scale exercise events for validation or rejection.

  4. Latest Pleistocene to Holocene thrust faulting paleoearthquakes at Monte Netto (Brescia, Italy): lessons learned from the Middle Ages seismic events in the Po Plain

    Science.gov (United States)

    Michetti, Alessandro Maria; Berlusconi, Andrea; Livio, Franz; Sileo, Giancanio; Zerboni, Andrea; Serva, Leonello; Vittori, Eutizio; Rodnight, Helena; Spötl, Christoph

    2010-05-01

    The seismicity of the Po Plain in Northern Italy is characterized by two strong Middle Ages earthquakes, the 1117, I° X MCS Verona, and the December 25, 1222, I° IX-X Brescia, events. Historical reports from these events describe relevant coseismic environmental effects, such as drainage changes, ground rupture and landslides. Due to the difficult interpretation of intensity data from such old seismic events, considerable uncertainty exists about their source parameters, and therefore about their causative tectonic structures. In a recent review, Stucchi et al. (2008) concluded that 'the historical data do not significantly help to constrain the assessment of the seismogenic potential of the area, which remains one of the most unknown, although potentially dangerous, seismic areas of the Italian region'. This issue needs therefore to be addressed by using the archaeological and geological evidence of past earthquakes, that is, archeoseismology and paleoseismology. Earthquake damage to archaeological sites in the study area has been the subject of several recent papers. Here we focus on new paleoseismological evidence, and in particular on the first observation of Holocene paleoseismic surface faulting in the Po Plain identified at the Monte Netto site, located ca. 10 km S of Brescia, in the area where the highest damage from the Christmas 1222 earthquake have been recorded. Monte Netto is a small hill, ca. 30 m higher than the surrounding piedmont plain, which represent the top of a growing fault-related fold belonging to the Quaternary frontal sector of the Southern Alps; the causative deep structure is a N-verging back thrust, well imaged in the industrial seismic reflection profiles kindly made available by ENI E&P. New trenching investigations have been conducted at the Cava Danesi of Monte Netto in October 2009, focused on the 1:10 scale analysis of the upper part of the 7 m high mid-Pleistocene to Holocene stratigraphic section exposed along the quarry

  5. Seismicity and tectonic tremor accompany the 2014 Gisborne Slow Slip Event: Insights from the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS) Experiment, New Zealand

    Science.gov (United States)

    Todd, E. K.; Schwartz, S. Y.; Sheehan, A. F.; Mochizuki, K.

    2016-12-01

    The northern Hikurangi Margin is host to some of the shallowest slow slip events (SSEs) in the world. Slow slip offshore Gisborne, New Zealand has been observed at depths as shallow as 2 km and may extend all the way to the trench. Gisborne SSEs are accompanied by tectonic tremor and increased levels of seismicity, but this activity has only been observed at the onshore, downdip edge of the slow slip patch. Between May 2014 and June 2015, 24 absolute pressure gauges, 10 broadband seismometers, and 5 short period seismometers were deployed offshore Gisborne along the east coast of the North Island of New Zealand as part of the HOBITSS Experiment. These instruments were in place during a large Gisborne SSE (peak slip 20 cm) in September and October 2014. Using this new ocean-derived dataset in conjunction with existing land data from the New Zealand National Seismograph Network operated by GeoNet (http://geonet.org.nz), we present an in-depth, systematic investigation of tremor and microseismicity associated with this shallow Gisborne SSE to further examine the spatial heterogeneity of slip processes on the shallow megathrust. Tremor and earthquakes are collocated with the geodetically inverted slow slip patch with tremor occurring offshore and earthquakes concentrated downdip of a shallowly subducted seamount near the region of peak displacement during the SSE. This discovery indicates that the region of the megathrust slipping in these SSEs is capable of multiple types of slip and understanding the spatiotemporal relationships between these strain release modes has implications for local seismic hazards.

  6. Seismic intensity assignments for the 2008 Andravida (NW Peloponnese, Greece strike-slip event (June 8, Mw=6.4 based on the application of the Environmental Seismic Intensity scale (ESI 2007 and the European Macroseismic scale (EMS-98

    Directory of Open Access Journals (Sweden)

    Spyridon D. Mavroulis

    2014-02-01

    Full Text Available On June 8, 2008, a strike-slip earthquake (Mw=6.4 was generated NE of the Andravida town (NW Peloponnese, western Greece due to the activation of the previously unknown western Achaia strike-slip fault zone (WAFZ. Extensive structural damage and earthquake environmental effects (EEE were induced in the NW Peloponnese, offering the opportunity to test and compare the ESI 2007 and the EMS-98 intensity scales in a moderate strike-slip event. No primary EEE were induced, while secondary EEE including seismic fractures, liquefaction phenomena, slope movements and hydrological anomalies were widely observed covering an area of about 800 km2. The lack of primary effects and the relatively small surface deformation with respect to the earthquake magnitude is due to the thick Gavrovo flysch layer in the affected area that isolated and absorbed the subsurface deformation from the surface. According to the application of the EMS-98 scale, damage to masonry buildings ranged from grade 3 to 5, while damage in most of R/C buildings ranged from grade 1 to 3. A maximum ESI 2007 intensity VIII-IX is recorded, while the maximum EMS-98 intensity is IX. For all the sites where intensity VIII has been recorded the ESI 2007 and the EMS-98 agree, but for others the ESI 2007 intensities values are lower by one or two degrees than the corresponding EMS-98 ones, as it is clearly concluded from the comparison of the produced isoseismals. An exception to this rule is the Valmi village, where considerable structural damage occurs (IXEMS-98 along with the lack of significant EEE (VESI 2007. This variability between the ESI 2007 and the EMS-98 intensity values is predominantly attributed to the vulnerability of old masonry buildings constructed with no seismic resistance design. Correlation of all existing data shows that the geological structure, the active tectonics, and the geotechnical characteristics of the alpine and post-alpine formations along with the construction

  7. Good practices for the operational safety management in the early recovery phase of a seismic event using GPR

    Science.gov (United States)

    Bianchini Ciampoli, Luca; Giulia Brancadoro, Maria; Benedetto, Andrea; D'Amico, Fabrizio; Calvi, Alessandro; Alani, Amir M.; Tosti, Fabio

    2017-04-01

    This study deals with a case report about the planning and the performance of GPR surveys carried out in the town of Amatrice, in the district of Rieti, Italy. As sadly known, the town has been hit by a 6.9 magnitude earthquake in the nighttime of August 24th 2016. The strength of the seism, along with the age and the deterioration rate of the structural asset, have caused the razing to the ground and the critical damaging of the majority of the buildings within the "red zone area", corresponding to the historical town center. In the early recovery phase taking place afterwards, the strong seismic swarm subsequent the main shake has sensitively slowed down the rescue and rehabilitation operations. Moreover, the main issue was related to the unsafety operational conditions of volunteers and firemen. To this effect, the geotechnical stability of the roads and the large operational areas represented critical issues, as up to 40 tons crane trucks were needed to put in safety the highest buildings, such as three-floor buildings and historical towers. In this framework, ground-penetrating radar (GPR) provided a valuable help in preliminary assessing the stability of the areas where the crane trucks were planned to operate as well as to be parked over. The main objective of the GPR tests was to verify the absence of possible cavities beneath the ground surface that could undermine the strength of the surface under heavy loadings. To that effect, a multi-frequency ground-coupled GPR system was used. This radar system can simultaneously collect data at both the frequencies of 600 MHz and 1600 MHz. Four different sites were surveyed, namely, two sections of the main road passed on by the cranes, and two machinery depot areas down by the towers. In the former case, the surveys were performed by parallel longitudinal scans, due to the significant longitudinal length of the sections, whereas in the latter, two grids with differing sizes were realized and scanned for producing

  8. Evaluation of Cross-Correlation Methods on a Massive Scale for Accurate Relocation of Seismic Events in East Asia

    Science.gov (United States)

    2006-04-21

    This is likely because of the deviation of the true crustal structure from the IASP91 model in the source area, a region of thick lithosphere . The effect...evaluate the stability of the double-difference solutions. In addition to the regional models listed in Table 3, a standard crustal model is used (IASP9 1...mantle velocity of vp = 8.04 km/s. Figure 7 compares, for each cluster, the locations of reference events obtained with the regional model ( thick black

  9. Events

    Directory of Open Access Journals (Sweden)

    Igor V. Karyakin

    2016-02-01

    Full Text Available The 9th ARRCN Symposium 2015 was held during 21st–25th October 2015 at the Novotel Hotel, Chumphon, Thailand, one of the most favored travel destinations in Asia. The 10th ARRCN Symposium 2017 will be held during October 2017 in the Davao, Philippines. International Symposium on the Montagu's Harrier (Circus pygargus «The Montagu's Harrier in Europe. Status. Threats. Protection», organized by the environmental organization «Landesbund für Vogelschutz in Bayern e.V.» (LBV was held on November 20-22, 2015 in Germany. The location of this event was the city of Wurzburg in Bavaria.

  10. Seismic Catalogue and Seismic Network in Haiti

    Science.gov (United States)

    Belizaire, D.; Benito, B.; Carreño, E.; Meneses, C.; Huerfano, V.; Polanco, E.; McCormack, D.

    2013-05-01

    The destructive earthquake occurred on January 10, 2010 in Haiti, highlighted the lack of preparedness of the country to address seismic phenomena. At the moment of the earthquake, there was no seismic network operating in the country, and only a partial control of the past seismicity was possible, due to the absence of a national catalogue. After the 2010 earthquake, some advances began towards the installation of a national network and the elaboration of a seismic catalogue providing the necessary input for seismic Hazard Studies. This paper presents the state of the works carried out covering both aspects. First, a seismic catalogue has been built, compiling data of historical and instrumental events occurred in the Hispaniola Island and surroundings, in the frame of the SISMO-HAITI project, supported by the Technical University of Madrid (UPM) and Developed in cooperation with the Observatoire National de l'Environnement et de la Vulnérabilité of Haiti (ONEV). Data from different agencies all over the world were gathered, being relevant the role of the Dominican Republic and Puerto Rico seismological services which provides local data of their national networks. Almost 30000 events recorded in the area from 1551 till 2011 were compiled in a first catalogue, among them 7700 events with Mw ranges between 4.0 and 8.3. Since different magnitude scale were given by the different agencies (Ms, mb, MD, ML), this first catalogue was affected by important heterogeneity in the size parameter. Then it was homogenized to moment magnitude Mw using the empirical equations developed by Bonzoni et al (2011) for the eastern Caribbean. At present, this is the most exhaustive catalogue of the country, although it is difficult to assess its degree of completeness. Regarding the seismic network, 3 stations were installed just after the 2010 earthquake by the Canadian Government. The data were sent by telemetry thought the Canadian System CARINA. In 2012, the Spanish IGN together

  11. Extending the inverse scattering series free-surface-multiple-elimination algorithm by accommodating the source property on data with interfering or proximal seismic events

    Science.gov (United States)

    Zhao, Lei; Yang, Jinlong; Weglein, Arthur B.

    2017-12-01

    The inverse scattering series free-surface-multiple-elimination (FSME) algorithm is modified and extended to accommodate the source property-source radiation pattern. That accommodation can provide additional value for the fidelity of the free-surface multiple predictions. The new extended FSME algorithm retains all the merits of the original algorithm, i.e., fully data-driven and with a requirement of no subsurface information. It is tested on a one-dimensional acoustic model with proximal and interfering seismic events, such as interfering primaries and multiples. The results indicate the new extended FSME algorithm can predict more accurate free-surface multiples than methods without the accommodation of the source property if the source has a radiation pattern. This increased effectiveness in prediction contributes to removing free-surface multiples without damaging primaries. It is important in such cases to increase predictive effectiveness because other prediction methods, such as the surface-related-multiple-elimination algorithm, has difficulties and problems in prediction accuracy, and those issues affect efforts to remove multiples through adaptive subtraction. Therefore accommodation of the source property can not only improve the effectiveness of the FSME algorithm, but also extend the method beyond the current algorithm (e.g. improving the internal multiple attenuation algorithm).

  12. Numerical simulations of temperature, dehydration, and flow fields associated with subduction of the Cocos plate, and its relation to the occurrence of interplate seismic events in southern Mexico

    Science.gov (United States)

    Suenaga, N.; Ji, Y.; Yoshioka, S.; Manea, M.; Manea, V. C.

    2016-12-01

    In southern Mexico, tectonic tremors mainly occur in the "flat slab region, and the last three SSEs in southern Mexico occurred in the shallower region. Besides, there are two seismic gaps of megathrust earthquakes in Guerrero and Oaxaca. To investigate generation mechanisms of megathrust earthquakes, tectonic tremors, and slow slip events (SSEs) in southern Mexico, we performed three-dimensional numerical simulations of temperature and mantle flow associated with subduction of the Cocos plate, and estimated dehydrated water content from the subducting plate. Here we considered retreat of the Middle American trench initiating about 16 Ma as one of the generation mechanisms of the slab flattening. In our model, we introduced the trench retreat effect during only a certain period between 16 Ma and present in order to best fit the observed heat flow data (from Global Heat Flow Database) as well as Curie point depths defined by the 580 ° isotherm. Our preliminary results show that trench rollback has a strong influence on temperature distribution. Models with trench rollback induce a weaker mantle wedge convection cell compared with models with stationary trench. Other parameter that is currently investigated in this study is the rate of trench retreat.

  13. The risks to miners, mines, and the public posed by large seismic events in the gold mining districts of South Africa

    CSIR Research Space (South Africa)

    Durrheim, RJ

    2006-10-01

    Full Text Available nearby deep gold mine, two mineworkers lost their lives and 3200 mineworkers were evacuated under difficult circumstances. The Chief Inspector of Mines initiated an investigation into the risks to miners, mines and the public arising from seismicity...

  14. A large thermogenic-methane release event in the SW Barents Sea, during the Last Glacial Maximum. Indications from numerical modelling and seismic reflection data

    Science.gov (United States)

    Anka, Z.; Rodrigues, E.; di Primio, R.; Ostanin, I.; Stoddart, D.; Horsfield, B.

    2011-12-01

    The Barents Sea, located in the Norwegian Artic area, has undergone a series of tectonic, paleoceanographic and paleo-climatic events during the Cenozoic, which most likely have caused the redistribution and leakage of hydrocarbons accumulations (Ohm et al., 2008). (Dimakis et al., 1998). Present-day under-filled accumulations are known to have leaked in the past providing a source of hydrocarbons, mostly thermogenic methane. However, the timing, extent and driving factors for this event are largely unconstrained. We built a 3D basin model of the Hammerfest Basin in the SW Barents Sea, in order to quantify the masses of liquid and gaseous hydrocarbons generated, accumulated and eventually leaked from the reservoirs during the evolution of the basin. Particular emphasis was placed on analysing the fate of leaked volumes within the dynamics of Plio-Quaternary glacial cycles and formation or destabilization of gas hydrate deposits. The model was calibrated with maturity and temperature well data and reconstructs, with large degree of accuracy, the composition and volume of the hydrocarbons, particularly the gaseous phase present in the main reservoirs. Our results predict the development of overpressures in the reservoirs due to the ice loading of the basin during the glacial periods. Pressure fluctuations derived from cyclic loading-unloading during the glacial-interglacial periods reached up to 5 MPa. The under-filled nature of the present-day accumulations would result from leakage events during the episodes of glacial retreat, in the transition from glacial to interglacial periods. Considerations of the gas hydrate stability conditions in the basin during the time span between 1.00Ma and ≈11,500 years indicate that the leaking thermogenic methane was probably trapped as gas hydrate deposits during the glacial events and then released at once upon hydrate destabilisation during the Last Glacial Maximun (LGM). These results are supported by the presence of km

  15. Evaluation of potential severe accidents during low power and shutdown operations at Grand Gulf, Unit 1. Volume 5: Analysis of core damage frequency from seismic events for plant operational state 5 during a refueling outage

    Energy Technology Data Exchange (ETDEWEB)

    Budnitz, R.J. [Future Resources Associates, Inc., Berkeley, CA (United States); Davis, P.R. [PRD Consulting (United States); Ravindra, M.K.; Tong, W.H. [EQE International, Inc., Irvine, CA (United States)

    1994-08-01

    In 1989 the US Nuclear Regulatory Commission (NRC) initiated an extensive program to examine carefully the potential risks during low-power and shutdown operations. The program included two parallel projects, one at Sandia National Laboratories studying a boiling water reactor (Grand Gulf), and the other at Brookhaven National Laboratory studying a pressurized water reactor (Surry Unit 1). Both the Sandia and Brookhaven projects have examined only accidents initiated by internal plant faults---so-called ``internal initiators.`` This project, which has explored the likelihood of seismic-initiated core damage accidents during refueling outage conditions, is complementary to the internal-initiator analyses at Brookhaven and Sandia. This report covers the seismic analysis at Grand Gulf. All of the many systems modeling assumptions, component non-seismic failure rates, and human effort rates that were used in the internal-initiator study at Grand Gulf have been adopted here, so that the results of the study can be as comparable as possible. Both the Sandia study and this study examine only one shutdown plant operating state (POS) at Grand Gulf, namely POS 5 representing cold shutdown during a refueling outage. This analysis has been limited to work analogous to a level-1 seismic PRA, in which estimates have been developed for the core-damage frequency from seismic events during POS 5. The results of the analysis are that the core-damage frequency for earthquake-initiated accidents during refueling outages in POS 5 is found to be quite low in absolute terms, less than 10{sup {minus}7}/year.

  16. Evaluation of potential severe accidents during low power and shutdown operations at Surry, Unit 1. Volume 5: Analysis of core damage frequency from seismic events during mid-loop operations

    Energy Technology Data Exchange (ETDEWEB)

    Budnitz, R.J. [Future Resources Associates, Inc., Berkeley, CA (United States); Davis, P.R. [PRD Consulting (United States); Ravindra, M.K.; Tong, W.H. [EQE International, Inc., Irvine, CA (United States)

    1994-08-01

    In 1989 the US Nuclear Regulatory Commission (NRC) initiated an extensive program to examine carefully the potential risks during low-power and shutdown operations. The program included two parallel projects, one at Brookhaven National Laboratory studying a pressurized water reactor (Surry Unit 1) and the other at Sandia National Laboratories studying a boiling water reactor (Grand Gulf). Both the Brookhaven and Sandia projects have examined only accidents initiated by internal plant faults--so-called ``internal initiators.`` This project, which has explored the likelihood of seismic-initiated core damage accidents during refueling shutdown conditions, is complementary to the internal-initiator analyses at Brookhaven and Sandia. This report covers the seismic analysis at Surry Unit 1. All of the many systems modeling assumptions, component non-seismic failure rates, and human error rates that were used in the internal-initiator study at Surry have been adopted here, so that the results of the two studies can be as comparable as possible. Both the Brookhaven study and this study examine only two shutdown plant operating states (POSs) during refueling outages at Surry, called POS 6 and POS 10, which represent mid-loop operation before and after refueling, respectively. This analysis has been limited to work analogous to a level-1 seismic PRA, in which estimates have been developed for the core-damage frequency from seismic events during POSs 6 and 10. The results of the analysis are that the core-damage frequency of earthquake-initiated accidents during refueling outages in POS 6 and POS 10 is found to be low in absolute terms, less than 10{sup {minus}6}/year.

  17. Seismic Consequence Abstraction

    Energy Technology Data Exchange (ETDEWEB)

    M. Gross

    2004-10-25

    The primary purpose of this model report is to develop abstractions for the response of engineered barrier system (EBS) components to seismic hazards at a geologic repository at Yucca Mountain, Nevada, and to define the methodology for using these abstractions in a seismic scenario class for the Total System Performance Assessment - License Application (TSPA-LA). A secondary purpose of this model report is to provide information for criticality studies related to seismic hazards. The seismic hazards addressed herein are vibratory ground motion, fault displacement, and rockfall due to ground motion. The EBS components are the drip shield, the waste package, and the fuel cladding. The requirements for development of the abstractions and the associated algorithms for the seismic scenario class are defined in ''Technical Work Plan For: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 171520]). The development of these abstractions will provide a more complete representation of flow into and transport from the EBS under disruptive events. The results from this development will also address portions of integrated subissue ENG2, Mechanical Disruption of Engineered Barriers, including the acceptance criteria for this subissue defined in Section 2.2.1.3.2.3 of the ''Yucca Mountain Review Plan, Final Report'' (NRC 2003 [DIRS 163274]).

  18. Data from investigation on seismic Sea-waves events in the Eastern Mediterranean from the Birth of Christ to 500 A.D.

    Directory of Open Access Journals (Sweden)

    J. ANTONOPOULOS

    1980-06-01

    Full Text Available The Eastern Mediterranean has a long history of damaging seismic sea
    waves (Tsunamis but a great number of them which are locally generated are small. They have caused no serious damage to the coasts because their
    energy is confined by many islands of the Greek Archipelagos. However,
    some of them have been rather severe and destructive to property and
    human life.
    This paper is comprised of data from an investigation into the activity
    of seismic sea waves in the Eastern Mediterranean from the Birth of
    Christ to 500 A.D. It contains a great amount of information concerning
    earthquakes, volcanic eruptions and seismic sea waves.
    All the available information has been compiled from historical accounts,
    archives, press reports, magazines and related works.

  19. Seismic hazard estimation of northern Iran using smoothed seismicity

    Science.gov (United States)

    Khoshnevis, Naeem; Taborda, Ricardo; Azizzadeh-Roodpish, Shima; Cramer, Chris H.

    2017-07-01

    This article presents a seismic hazard assessment for northern Iran, where a smoothed seismicity approach has been used in combination with an updated seismic catalog and a ground motion prediction equation recently found to yield good fit with data. We evaluate the hazard over a geographical area including the seismic zones of Azerbaijan, the Alborz Mountain Range, and Kopeh-Dagh, as well as parts of other neighboring seismic zones that fall within our region of interest. In the chosen approach, seismic events are not assigned to specific faults but assumed to be potential seismogenic sources distributed within regular grid cells. After performing the corresponding magnitude conversions, we decluster both historical and instrumental seismicity catalogs to obtain earthquake rates based on the number of events within each cell, and smooth the results to account for the uncertainty in the spatial distribution of future earthquakes. Seismicity parameters are computed for each seismic zone separately, and for the entire region of interest as a single uniform seismotectonic region. In the analysis, we consider uncertainties in the ground motion prediction equation, the seismicity parameters, and combine the resulting models using a logic tree. The results are presented in terms of expected peak ground acceleration (PGA) maps and hazard curves at selected locations, considering exceedance probabilities of 2 and 10% in 50 years for rock site conditions. According to our results, the highest levels of hazard are observed west of the North Tabriz and east of the North Alborz faults, where expected PGA values are between about 0.5 and 1 g for 10 and 2% probability of exceedance in 50 years, respectively. We analyze our results in light of similar estimates available in the literature and offer our perspective on the differences observed. We find our results to be helpful in understanding seismic hazard for northern Iran, but recognize that additional efforts are necessary to

  20. Characterising Seismic Hazard Input for Analysis Risk to Multi-System Infrastructures: Application to Scenario Event-Based Models and extension to Probabilistic Risk

    Science.gov (United States)

    Weatherill, G. A.; Silva, V.

    2011-12-01

    The potential human and economic cost of earthquakes to complex urban infrastructures has been demonstrated in the most emphatic manner by recent large earthquakes such as that of Haiti (February 2010), Christchurch (September 2010 and February 2011) and Tohoku (March 2011). Consideration of seismic risk for a homogenous portfolio, such as a single building typology or infrastructure, or independent analyses of separate typologies or infrastructures, are insufficient to fully characterise the potential impacts that arise from inter-connected system failure. Individual elements of each infrastructure may be adversely affected by different facets of the ground motion (e.g. short-period acceleration, long-period displacement, cumulative energy input etc.). The accuracy and efficiency of the risk analysis is dependent on the ability to characterise these multiple features of the ground motion over a spatially distributed portfolio of elements. The modelling challenges raised by this extension to multi-system analysis of risk have been a key focus of the European Project "Systemic Seismic Vulnerability and Risk Analysis for Buildings, Lifeline Networks and Infrastructures Safety Gain (SYNER-G)", and are expected to be developed further within the Global Earthquake Model (GEM). Seismic performance of a spatially distributed infrastructure during an earthquake may be assessed by means of Monte Carlo simulation, in order to incorporate the aleatory variability of the ground motion into the network analysis. Methodologies for co-simulating large numbers of spatially cross-correlated ground motion fields are appraised, and their potential impacts on a spatially distributed portfolio of mixed building typologies assessed using idealised case study scenarios from California and Europe. Potential developments to incorporate correlation and uncertainty in site amplification and geotechnical hazard are also explored. Whilst the initial application of the seismic risk analysis is

  1. Seismic Data Gathering and Validation

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Justin [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-02-01

    Three recent earthquakes in the last seven years have exceeded their design basis earthquake values (so it is implied that damage to SSC’s should have occurred). These seismic events were recorded at North Anna (August 2011, detailed information provided in [Virginia Electric and Power Company Memo]), Fukushima Daichii and Daini (March 2011 [TEPCO 1]), and Kaswazaki-Kariwa (2007, [TEPCO 2]). However, seismic walk downs at some of these plants indicate that very little damage occurred to safety class systems and components due to the seismic motion. This report presents seismic data gathered for two of the three events mentioned above and recommends a path for using that data for two purposes. One purpose is to determine what margins exist in current industry standard seismic soil-structure interaction (SSI) tools. The second purpose is the use the data to validated seismic site response tools and SSI tools. The gathered data represents free field soil and in-structure acceleration time histories data. Gathered data also includes elastic and dynamic soil properties and structural drawings. Gathering data and comparing with existing models has potential to identify areas of uncertainty that should be removed from current seismic analysis and SPRA approaches. Removing uncertainty (to the extent possible) from SPRA’s will allow NPP owners to make decisions on where to reduce risk. Once a realistic understanding of seismic response is established for a nuclear power plant (NPP) then decisions on needed protective measures, such as SI, can be made.

  2. Automatic phase detection in seismic data using the discrete wavelet transform

    NARCIS (Netherlands)

    P.J. Oonincx

    1998-01-01

    textabstractSeismic data consist of traces, which contain information about a seismic event, but in some period of time the traces may be just noise. A trace which c ontains seismic information, is called a seismic signal. Seismic signals consist of several typically short energy bursts, called

  3. Probabilistic Seismic Hazard Analysis for Yemen

    Directory of Open Access Journals (Sweden)

    Rakesh Mohindra

    2012-01-01

    Full Text Available A stochastic-event probabilistic seismic hazard model, which can be used further for estimates of seismic loss and seismic risk analysis, has been developed for the territory of Yemen. An updated composite earthquake catalogue has been compiled using the databases from two basic sources and several research publications. The spatial distribution of earthquakes from the catalogue was used to define and characterize the regional earthquake source zones for Yemen. To capture all possible scenarios in the seismic hazard model, a stochastic event set has been created consisting of 15,986 events generated from 1,583 fault segments in the delineated seismic source zones. Distribution of horizontal peak ground acceleration (PGA was calculated for all stochastic events considering epistemic uncertainty in ground-motion modeling using three suitable ground motion-prediction relationships, which were applied with equal weight. The probabilistic seismic hazard maps were created showing PGA and MSK seismic intensity at 10% and 50% probability of exceedance in 50 years, considering local soil site conditions. The resulting PGA for 10% probability of exceedance in 50 years (return period 475 years ranges from 0.2 g to 0.3 g in western Yemen and generally is less than 0.05 g across central and eastern Yemen. The largest contributors to Yemen’s seismic hazard are the events from the West Arabian Shield seismic zone.

  4. Seismic Creep

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seismic creep is the constant or periodic movement on a fault as contrasted with the sudden erupture associated with an earthquake. It is a usually slow deformation...

  5. Seismicity of the Jalisco Block

    Science.gov (United States)

    Nunez-Cornu, F. J.; Rutz, M.; Camarena-Garcia, M.; Trejo-Gomez, E.; Reyes-Davila, G.; Suarez-Plascencia, C.

    2002-12-01

    In April 2002 began to transmit the stations of the first phase of Jalisco Telemetric Network located at the northwest of Jalisco Block and at the area of Volcan de Fuego (Colima Volcano), in June were deployed four additional MarsLite portable stations in the Bahia de Banderas area, and by the end of August one more portable station at Ceboruco Volcano. The data of these stations jointly with the data from RESCO (Colima Telemetric Network) give us the minimum seismic stations coverage to initiate in a systematic and permanent way the study of the seismicity in this very complex tectonic region. A preliminary analysis of seismicity based on the events registered by the networks using a shutter algorithm, confirms several important features proposed by microseismicity studies carried out between 1996 and 1998. A high level of seismicity inside and below of Rivera plate is observed, this fact suggest a very complex stress pattern acting on this plate. Shallow seismicity at south and east of Bahia de Banderas also suggest a complex stress pattern in this region of the Jalisco Block, events at more than 30 km depth are located under the mouth of the bay and in face of it, a feature denominated Banderas Boundary mark the change of the seismic regime at north of this latitude (20.75°N), however some shallow events were located at the region of Nayarit.

  6. Seismic bearing

    Science.gov (United States)

    Power, Dennis

    2009-05-01

    Textron Systems (Textron) has been using geophones for target detection for many years. This sensing capability was utilized for detection and classification purposes only. Recently Textron has been evaluating multiaxis geophones to calculate bearings and track targets more specifically personnel. This capability will not only aid the system in locating personnel in bearing space or cartesian space but also enhance detection and reduce false alarms. Textron has been involved in the testing and evaluation of several sensors at multiple sites. One of the challenges of calculating seismic bearing is an adequate signal to noise ratio. The sensor signal to noise ratio is a function of sensor coupling to the ground, seismic propagation and range to target. The goals of testing at multiple sites are to gain a good understanding of the maximum and minimum ranges for bearing and detection and to exploit that information to tailor sensor system emplacement to achieve desired performance. Test sites include 10A Site Devens, MA, McKenna Airfield Ft. Benning, GA and Yuma Proving Ground Yuma, AZ. Geophone sensors evaluated include a 28 Hz triax spike, a 15 Hz triax spike and a hybrid triax spike consisting of a 10 Hz vertical geophone and two 28 Hz horizontal geophones. The algorithm uses raw seismic data to calculate the bearings. All evaluated sensors have triaxial geophone configuration mounted to a spike housing/fixture. The suite of sensors also compares various types of geophones to evaluate benefits in lower bandwidth. The data products of these tests include raw geophone signals, seismic features, seismic bearings, seismic detection and GPS position truth data. The analyses produce Probability of Detection vs range, bearing accuracy vs range, and seismic feature level vs range. These analysis products are compared across test sites and sensor types.

  7. SEISMIC ANALYSIS FOR PRECLOSURE SAFETY

    Energy Technology Data Exchange (ETDEWEB)

    E.N. Lindner

    2004-12-03

    The purpose of this seismic preclosure safety analysis is to identify the potential seismically-initiated event sequences associated with preclosure operations of the repository at Yucca Mountain and assign appropriate design bases to provide assurance of achieving the performance objectives specified in the Code of Federal Regulations (CFR) 10 CFR Part 63 for radiological consequences. This seismic preclosure safety analysis is performed in support of the License Application for the Yucca Mountain Project. In more detail, this analysis identifies the systems, structures, and components (SSCs) that are subject to seismic design bases. This analysis assigns one of two design basis ground motion (DBGM) levels, DBGM-1 or DBGM-2, to SSCs important to safety (ITS) that are credited in the prevention or mitigation of seismically-initiated event sequences. An application of seismic margins approach is also demonstrated for SSCs assigned to DBGM-2 by showing a high confidence of a low probability of failure at a higher ground acceleration value, termed a beyond-design basis ground motion (BDBGM) level. The objective of this analysis is to meet the performance requirements of 10 CFR 63.111(a) and 10 CFR 63.111(b) for offsite and worker doses. The results of this calculation are used as inputs to the following: (1) A classification analysis of SSCs ITS by identifying potential seismically-initiated failures (loss of safety function) that could lead to undesired consequences; (2) An assignment of either DBGM-1 or DBGM-2 to each SSC ITS credited in the prevention or mitigation of a seismically-initiated event sequence; and (3) A nuclear safety design basis report that will state the seismic design requirements that are credited in this analysis. The present analysis reflects the design information available as of October 2004 and is considered preliminary. The evolving design of the repository will be re-evaluated periodically to ensure that seismic hazards are properly

  8. Causality between expansion of seismic cloud and maximum magnitude of induced seismicity in geothermal field

    Science.gov (United States)

    Mukuhira, Yusuke; Asanuma, Hiroshi; Ito, Takatoshi; Häring, Markus

    2016-04-01

    Occurrence of induced seismicity with large magnitude is critical environmental issues associated with fluid injection for shale gas/oil extraction, waste water disposal, carbon capture and storage, and engineered geothermal systems (EGS). Studies for prediction of the hazardous seismicity and risk assessment of induced seismicity has been activated recently. Many of these studies are based on the seismological statistics and these models use the information of the occurrence time and event magnitude. We have originally developed physics based model named "possible seismic moment model" to evaluate seismic activity and assess seismic moment which can be ready to release. This model is totally based on microseismic information of occurrence time, hypocenter location and magnitude (seismic moment). This model assumes existence of representative parameter having physical meaning that release-able seismic moment per rock volume (seismic moment density) at given field. Seismic moment density is to be estimated from microseismic distribution and their seismic moment. In addition to this, stimulated rock volume is also inferred by progress of microseismic cloud at given time and this quantity can be interpreted as the rock volume which can release seismic energy due to weakening effect of normal stress by injected fluid. Product of these two parameters (equation (1)) provide possible seismic moment which can be released from current stimulated zone as a model output. Difference between output of this model and observed cumulative seismic moment corresponds the seismic moment which will be released in future, based on current stimulation conditions. This value can be translated into possible maximum magnitude of induced seismicity in future. As this way, possible seismic moment can be used to have feedback to hydraulic stimulation operation in real time as an index which can be interpreted easily and intuitively. Possible seismic moment is defined as equation (1), where D

  9. Seismic Studies

    Energy Technology Data Exchange (ETDEWEB)

    R. Quittmeyer

    2006-09-25

    This technical work plan (TWP) describes the efforts to develop and confirm seismic ground motion inputs used for preclosure design and probabilistic safety 'analyses and to assess the postclosure performance of a repository at Yucca Mountain, Nevada. As part of the effort to develop seismic inputs, the TWP covers testing and analyses that provide the technical basis for inputs to the seismic ground-motion site-response model. The TWP also addresses preparation of a seismic methodology report for submission to the U.S. Nuclear Regulatory Commission (NRC). The activities discussed in this TWP are planned for fiscal years (FY) 2006 through 2008. Some of the work enhances the technical basis for previously developed seismic inputs and reduces uncertainties and conservatism used in previous analyses and modeling. These activities support the defense of a license application. Other activities provide new results that will support development of the preclosure, safety case; these results directly support and will be included in the license application. Table 1 indicates which activities support the license application and which support licensing defense. The activities are listed in Section 1.2; the methods and approaches used to implement them are discussed in more detail in Section 2.2. Technical and performance objectives of this work scope are: (1) For annual ground motion exceedance probabilities appropriate for preclosure design analyses, provide site-specific seismic design acceleration response spectra for a range of damping values; strain-compatible soil properties; peak motions, strains, and curvatures as a function of depth; and time histories (acceleration, velocity, and displacement). Provide seismic design inputs for the waste emplacement level and for surface sites. Results should be consistent with the probabilistic seismic hazard analysis (PSHA) for Yucca Mountain and reflect, as appropriate, available knowledge on the limits to extreme ground

  10. Use of the t-distribution to construct seismic hazard curves for seismic probabilistic safety assessments

    Energy Technology Data Exchange (ETDEWEB)

    Yee, Eric [KEPCO International Nuclear Graduate School, Dept. of Nuclear Power Plant Engineering, Ulsan (Korea, Republic of)

    2017-03-15

    Seismic probabilistic safety assessments are used to help understand the impact potential seismic events can have on the operation of a nuclear power plant. An important component to seismic probabilistic safety assessment is the seismic hazard curve which shows the frequency of seismic events. However, these hazard curves are estimated assuming a normal distribution of the seismic events. This may not be a strong assumption given the number of recorded events at each source-to-site distance. The use of a normal distribution makes the calculations significantly easier but may underestimate or overestimate the more rare events, which is of concern to nuclear power plants. This paper shows a preliminary exploration into the effect of using a distribution that perhaps more represents the distribution of events, such as the t-distribution to describe data. The integration of a probability distribution with potentially larger tails basically pushes the hazard curves outward, suggesting a different range of frequencies for use in seismic probabilistic safety assessments. Therefore the use of a more realistic distribution results in an increase in the frequency calculations suggesting rare events are less rare than thought in terms of seismic probabilistic safety assessment. However, the opposite was observed with the ground motion prediction equation considered.

  11. Seismic Symphonies

    Science.gov (United States)

    Strinna, Elisa; Ferrari, Graziano

    2015-04-01

    The project started in 2008 as a sound installation, a collaboration between an artist, a barrel organ builder and a seismologist. The work differs from other attempts of sound transposition of seismic records. In this case seismic frequencies are not converted automatically into the "sound of the earthquake." However, it has been studied a musical translation system that, based on the organ tonal scale, generates a totally unexpected sequence of sounds which is intended to evoke the emotions aroused by the earthquake. The symphonies proposed in the project have somewhat peculiar origins: they in fact come to life from the translation of graphic tracks into a sound track. The graphic tracks in question are made up by copies of seismograms recorded during some earthquakes that have taken place around the world. Seismograms are translated into music by a sculpture-instrument, half a seismograph and half a barrel organ. The organ plays through holes practiced on paper. Adapting the documents to the instrument score, holes have been drilled on the waves' peaks. The organ covers about three tonal scales, starting from heavy and deep sounds it reaches up to high and jarring notes. The translation of the seismic records is based on a criterion that does match the highest sounds to larger amplitudes with lower ones to minors. Translating the seismogram in the organ score, the larger the amplitude of recorded waves, the more the seismogram covers the full tonal scale played by the barrel organ and the notes arouse an intense emotional response in the listener. Elisa Strinna's Seismic Symphonies installation becomes an unprecedented tool for emotional involvement, through which can be revived the memory of the greatest disasters of over a century of seismic history of the Earth. A bridge between art and science. Seismic Symphonies is also a symbolic inversion: the instrument of the organ is most commonly used in churches, and its sounds are derived from the heavens and

  12. Passive Seismic Imaging

    Science.gov (United States)

    Artman, B. W.

    2003-12-01

    Traditionally, passive seismology connotes the use of earthquake signals from continuously recording receivers. Small time windows around the arrivals of earthquakes are then analyzed in myriad fashion. I will distinguish from this body of work, the notion of passive seismic imaging, which requires no knowledge of the time or characteristics of a source event. Instead, by using the ambient noise in the subsurface with all orders of scattering and thus randomized directionality, passive seismic imaging can produce results analogous to conventional controlled source experiments. Mathematical proof of the concept of passive seismic imaging has been presented in the literature from several foundations. The results reduce to the simple concept of cross-correlating many long recordings within a simultaneously deployed array. This generates panels with the kinematics of a shot-gather from a standard reflection seismic acquisition effort. Results from synthetic data sets show the validity of the method for point diffractor, and layered earth models. Noting the similarity of form of the standard approach to produce shot-gathers with the imaging condition of shot-profile migration, I then show that migrating the raw passive seismic data without the correlation step produces the the correct image. The synthetic data from above is used to demonstrate the technique. By comparison, this image is of better quality, and demands less compute time, than migrating the data having been cross-correlated first. Finally, both techniques are used to process a 2x2 meter, 72-channel array recorded on the beach sand of Monterey Bay, California. Approximately one meter below the sand, a six inch diameter plastic pipe was buried to serve as a target.

  13. Discrimination of Earthquake and Blast Seismicity in Western Alberta

    Science.gov (United States)

    Spriggs, N.; Law, A.; Yenier, E.; Reynen, A.; Baturan, D.

    2015-12-01

    Recorded seismicity in western Alberta is caused by natural and induced earthquakes or blast events from mining and quarry operations. Accurate discrimination of earthquakes from blast events is crucial for evaluating recent seismicity with respect to the historical catalog and for assessing seismic hazards associated with naturally occurring or induced seismicity. In general, blast events are discriminated from earthquakes based on their proximity to active mines and quarries in addition to day-of-week and time-of-day timing patterns. In some parts of western Alberta, however, seismicity originates in regions with active mines, historical earthquake seismicity, and hydraulic fracturing operations. Based on timing patterns or event locations alone, natural or induced seismicity may be misidentified as mining activity. Several studies report that relative differences in Fourier or response spectra can be used to discriminate blast and earthquake events. Other studies report that the relative timing and amplitude of seismic phases may provide useful metrics for classifying blast events. Here we propose an alternative method that accounts for both differences in phase spectra and phase timing and amplitude. In particular, we evaluate the normalized time integral for characteristic functions of particle motion from confirmed blast and earthquake events recorded by regional Alberta seismic networks. We then use these time-integral profiles to re-classify events that are initially categorized as suspected blasts based on timing pattern and event location indicators.

  14. Post-seismic relaxation from geodetic and seismic data

    Directory of Open Access Journals (Sweden)

    Mikhail V. Rodkin

    2017-01-01

    Full Text Available We have examined the aftershock sequence and the post-seismic deformation process of the Parkfield earthquake (2004, M = 6, California, USA source area using GPS data. This event was chosen because of the possibility of joint analysis of data from the rather dense local GPS network (from SOPAC Internet archive and of the availability of the rather detailed aftershock sequence data (http://www.ncedc.org/ncedc/catalog-search.html. The relaxation process of post-seismic deformation prolongs about the same 400 days as the seismic aftershock process does. Thus, the aftershock process and the relaxation process in deformation could be the different sides of the same process. It should be noted that the ratio of the released seismic energy and of the GPS obtained deformation is quite different for the main shock and for the aftershock stage. The ratio of the released seismic energy to the deformation value decreases essentially for the post-shock process. The similar change in the seismic energy/deformation value ratio is valid in a few other strong earthquakes. Thus, this decrease seems typical of aftershock sequences testifying for decrease of ratio of elastic to inelastic deformation in the process of post-shock relaxation when the source area appears to be mostly fractured after the main shock occurs, but the healing process had no yet sufficient time to develop.

  15. Seismic Isolation Working Meeting Gap Analysis Report

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Justin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sabharwall, Piyush [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-09-01

    The ultimate goal in nuclear facility and nuclear power plant operations is operating safety during normal operations and maintaining core cooling capabilities during off-normal events including external hazards. Understanding the impact external hazards, such as flooding and earthquakes, have on nuclear facilities and NPPs is critical to deciding how to manage these hazards to expectable levels of risk. From a seismic risk perspective the goal is to manage seismic risk. Seismic risk is determined by convolving the seismic hazard with seismic fragilities (capacity of systems, structures, and components (SSCs)). There are large uncertainties associated with evolving nature of the seismic hazard curves. Additionally there are requirements within DOE and potential requirements within NRC to reconsider updated seismic hazard curves every 10 years. Therefore opportunity exists for engineered solutions to manage this seismic uncertainty. One engineered solution is seismic isolation. Current seismic isolation (SI) designs (used in commercial industry) reduce horizontal earthquake loads and protect critical infrastructure from the potentially destructive effects of large earthquakes. The benefit of SI application in the nuclear industry is being recognized and SI systems have been proposed, in the American Society of Civil Engineers (ASCE) 4 standard, to be released in 2014, for Light Water Reactors (LWR) facilities using commercially available technology. However, there is a lack of industry application to the nuclear industry and uncertainty with implementing the procedures outlined in ASCE-4. Opportunity exists to determine barriers associated with implementation of current ASCE-4 standard language.

  16. Local seismicity in the area of Tornio River (northern Fennoscandia) revealed by analysis of local events registered by the POLENET/LAPNET array

    Science.gov (United States)

    Kozlovskaya, E.; Usoltseva, O.; Konstantinovskaya, N.

    2012-04-01

    The region of Tornio river (22-26 deg E and 66.5-69 deg N) is very interesting for seismological studies because it is crossed by systems of tectonic faults spreading in two different directions. 56 local earthquakes originated from this region were recorded by the POLENET/LAPNET temporary array from May, 2007 to May, 2009. Hypocenter depths of earthquakes are in the range of 1-35 km and their magnitudes vary from 0.8 to 2.2. For events detection we used the bulletin of the Institute of Seismology (Helsinki university) and Norway Global Beam Forming bulletin, compiled on the base of automatic detection of events, using the data of Noress, Arcess, Finess, SPA, HFS, APA arrays. In addition to local earthquakes, the array recorded 364 blasts from this region during the POLENET/LAPNET observation period. The events were relocated using manually measured travel times of refracted P waves from events at local distances (less than 200 km) and the 1-D velocity model along the wide-angle reflection and refraction HUKKA profile. The epicenters of relocated events show good correlation with known faults in the region. For each earthquake we constructed travel-time curves with reduction velocity of 8 km/s and compared them with the theoretical travel-time curves, in order to avoid phase misinterpretation. We found out that the largest reduction of travel time residuals during relocation was reached for deep earthquakes, due to more precise depth determination. The other aim of our study was to estimate what part of travel time residuals is not connected with the reference 1D velocity model and accuracy of location, but is rather due to 3-D heterogeneities in the crust. We also analyzed the amplitude characteristics of P-wave arrivals from different layers in the crust and upper mantle and also compared spectrograms of deep earthquakes, shallow earthquakes and blasts.

  17. Expected Seismicity and the Seismic Noise Environment of Europa

    Science.gov (United States)

    Panning, Mark P.; Stähler, Simon C.; Huang, Hsin-Hua; Vance, Steven D.; Kedar, Sharon; Tsai, Victor C.; Pike, William T.; Lorenz, Ralph D.

    2018-01-01

    Seismic data will be a vital geophysical constraint on internal structure of Europa if we land instruments on the surface. Quantifying expected seismic activity on Europa both in terms of large, recognizable signals and ambient background noise is important for understanding dynamics of the moon, as well as interpretation of potential future data. Seismic energy sources will likely include cracking in the ice shell and turbulent motion in the oceans. We define a range of models of seismic activity in Europa's ice shell by assuming each model follows a Gutenberg-Richter relationship with varying parameters. A range of cumulative seismic moment release between 1016 and 1018 Nm/yr is defined by scaling tidal dissipation energy to tectonic events on the Earth's moon. Random catalogs are generated and used to create synthetic continuous noise records through numerical wave propagation in thermodynamically self-consistent models of the interior structure of Europa. Spectral characteristics of the noise are calculated by determining probabilistic power spectral densities of the synthetic records. While the range of seismicity models predicts noise levels that vary by 80 dB, we show that most noise estimates are below the self-noise floor of high-frequency geophones but may be recorded by more sensitive instruments. The largest expected signals exceed background noise by ˜50 dB. Noise records may allow for constraints on interior structure through autocorrelation. Models of seismic noise generated by pressure variations at the base of the ice shell due to turbulent motions in the subsurface ocean may also generate observable seismic noise.

  18. Multicomponent ensemble models to forecast induced seismicity

    Science.gov (United States)

    Király-Proag, E.; Gischig, V.; Zechar, J. D.; Wiemer, S.

    2018-01-01

    In recent years, human-induced seismicity has become a more and more relevant topic due to its economic and social implications. Several models and approaches have been developed to explain underlying physical processes or forecast induced seismicity. They range from simple statistical models to coupled numerical models incorporating complex physics. We advocate the need for forecast testing as currently the best method for ascertaining if models are capable to reasonably accounting for key physical governing processes—or not. Moreover, operational forecast models are of great interest to help on-site decision-making in projects entailing induced earthquakes. We previously introduced a standardized framework following the guidelines of the Collaboratory for the Study of Earthquake Predictability, the Induced Seismicity Test Bench, to test, validate, and rank induced seismicity models. In this study, we describe how to construct multicomponent ensemble models based on Bayesian weightings that deliver more accurate forecasts than individual models in the case of Basel 2006 and Soultz-sous-Forêts 2004 enhanced geothermal stimulation projects. For this, we examine five calibrated variants of two significantly different model groups: (1) Shapiro and Smoothed Seismicity based on the seismogenic index, simple modified Omori-law-type seismicity decay, and temporally weighted smoothed seismicity; (2) Hydraulics and Seismicity based on numerically modelled pore pressure evolution that triggers seismicity using the Mohr-Coulomb failure criterion. We also demonstrate how the individual and ensemble models would perform as part of an operational Adaptive Traffic Light System. Investigating seismicity forecasts based on a range of potential injection scenarios, we use forecast periods of different durations to compute the occurrence probabilities of seismic events M ≥ 3. We show that in the case of the Basel 2006 geothermal stimulation the models forecast hazardous levels

  19. Slip Distribution of Two Recent Large Earthquakes in the Guerrero Segment of the Mexican Subduction Zone, and Their Relation to Previous Earthquakes, Silent Slip Events and Seismic Gaps

    Science.gov (United States)

    Hjorleifsdottir, V.; Ji, C.; Iglesias, A.; Cruz-Atienza, V. M.; Singh, S. K.

    2016-12-01

    In 2012 and 2014 mega-thrust earthquakes occurred approximately 300 km apart, in the state of Guerrero, Mexico. The westernmost half of the segment between them has not had a large earthquake in at least 100 years and most of the easternmost half last broke in 1957. However, down dip of both earthquakes, silent slip events have been reported, as well as in the gap between them (Kostoglodov et al 2003, Graham 2014). There are indications that the westernmost half has different frictional properties than the areas surrounds it. However, the two events at the edges of the zone also seem to behave in different manners, indicating a broad range of frictional properties in this area, with changes occurring over short distances. The 2012/03/20, M7.5 earthquake occurred near the Guerrero-Oaxaca border, between the towns of Ometepec (Gro.) and Pinotepa Nacional (Oax.). This earthquake is noteworthy for breaking the same asperities as two previously recorded earthquakes, the M7.2 1937 and M6.9 1982(a) earthquakes, in very large "repeating earthquakes". Furthermore, the density of repeating smaller events is larger in this zone than in other parts of the subduction zone (Dominguez et al, submitted) and this earthquake has had very many aftershocks for its size (UNAM Seis. group, 2013). The 2012 event may have broken two asperities (UNAM Seis. group, 2013). How the two asperities relate to the previous relatively smaller "large events", to the repeating earthquakes, the high number of aftershocks and to the slow slip event is not clear. The 2014/04/18 M 7.2 earthquake broke a patch on the edge of the Guerrero gap, that previously broke in the 1979 M7.4 earthquake as well as the 1943 M 7.4 earthquake. This earthquake, despite being smaller, had a much larger duration, few aftershocks and clearly ruptured two separate patches (UNAM Seis. group 2015). In this work we estimate the slip distributions for the 2012 and 2014 earthquakes, by combining the data used separately in

  20. Re-Evaluating the Geological Evidence for Late Holocene Marine Incursion Events along the Guerrero Seismic Gap on the Pacific Coast of Mexico.

    Directory of Open Access Journals (Sweden)

    Thomas A Bianchette

    Full Text Available Despite the large number of tsunamis that impact Mexico's Pacific coast, stratigraphic studies focusing on geological impacts are scanty, making it difficult to assess the long-term risks for this vulnerable region. Surface samples and six cores were taken from Laguna Mitla near Acapulco to examine sedimentological and geochemical evidence for marine incursion events. Sediment cores collected from behind the beach barrier are dominated by intercalated layers of peat and inorganic sediments, mostly silt and clay, with little or no sand. Sand- and shell-rich clastic layers with high levels of sulfur, calcium, and strontium only occur adjacent to the relict beach ridge remnants near the center of the lagoon. With the exception of one thin fine sand layer, the absence of sand in the near-shore cores and the predominance of the terrigenous element titanium in the inorganic layers, evidently eroded from the surrounding hillslopes, suggests that these large-grained intervals do not represent episodic marine incursions, but rather were likely formed by the erosion and redeposition of older marine deposits derived from the beach ridge remnants when water levels were high. These results do not support the occurrence of a large tsunami event at Laguna Mitla during the Late Holocene.

  1. Seismic and hydroacoustic investigations near Ascension Island

    Science.gov (United States)

    Hanson, Jeffrey Acton

    A local seismicity study is conducted observing earthquakes near Ascension Island including a segment of the Mid-Atlantic Ridge (MAR). We use data collected from permanently deployed hydroacoustic and seismic instruments over a 2 year period to determine patterns in the ridge seismicity. Earthquakes are observed on the MAR 1 to 2 orders of magnitude smaller than the global catalogs can in this part of the world. Epicenters are determined for 77 of the events using the seismic and hydroacoustic data. Ridge seismicity is mainly confined to the median valley although systematic errors could give mislocations up to 10 km in one direction. The seismicity is infrequent at the segment center and increases towards the segment ends. Seismicity is not seen at the inside corner high. We do not observe direct evidence for seismicity along an anomalous shallow section of the MAR which also appears aseismic in the global catalogs. A simple method is described whereby station-to-source azimuths are estimated by fitting a plane wave to envelope functions of T-phases observed on 5 hydrophones surrounding Ascension Island, South Atlantic Ocean. When applied to a data set of 55 earthquakes with T-phases observed on at least 3 instruments, estimated azimuths have a standard deviation of 3.6 degrees compared to azimuths predicted from global catalog epicentral locations. The standard deviation decreases to 2 degrees if T-phase data from all 5 hydrophones are used. The performance of a seismic T-phase station for recording hydroacoustic phases is examined by comparing seismic and hydrophone T-phases from MAR earthquakes at Ascension Island. Variations between the corrected hydroacoustic amplitudes and seismic amplitudes are compared with physical parameters such as the gradient of the topography at the island-ocean interface. T-phases can have various modal structures which will couple into the island differently. Thus events from the same direction have different signal loss.

  2. Site seismic studies in the damaged area of Visso village after the 24th August 2016, Mw 6.0, earthquake event

    Science.gov (United States)

    Gaudiosi, Iolanda; Vignaroli, Gianluca; Sirianni, Pietro; Giallini, Silvia; Mori, Federico; Polpetta, Federica; Razzano, Roberto; Simionato, Maurizio; Moscatelli, Massimiliano

    2017-04-01

    This work presents results coming from a geophysical study and numerical analyses in the damaged area of the Visso village, aiming at discussing factors leading to the observed differential damages after the 24th August 2016 Mw 6.0 earthquake event. Visso village is located in a morphological depressed area of the Sibillini Mountains, at the Umbria-Marche regional boundary, about 28 km north from the 24th August 2016 epicentre. Following insights from the available geological cartography at 1:10.000 scale, a preliminary geophysical survey has been performed in the damaged area in order to constrain geometries and extent of the subsoil lithotypes. Then, these results have been used to retrieve a Vs profile close to the most heavily damaged buildings. This latter has been used to constrain the geological - geotechnical model for numerical analyses aimed at deriving the motion at the ground level in the study area. In particular, linear equivalent simulations have been performed by means of EERA and QUAD4M codes. The waveforms have been obtained using as input motion the time history recorded during the 24th August mainshock at Spoleto Monteluco (SPM) site. Preliminary analyses highlights that the local geology and dynamic parameters of uppermost geological layers may have influenced the ground motion, increasing the source effect at the site. Our preliminary results indicate a possible correlation of damaging to the thickness and shape of the geological units. Nevertheless, further analyses are necessary to highlight any 3D and/or non - linear soil behaviour effects in order to compare them to the intrinsic buildings vulnerability, according to the EMS98 guidelines. Our data can be used for possible correlation of stronger damaging occurred during the 30th October 2016 event (Mw 6.5), which caused the collapses of many buildings.

  3. National Seismic Network of Georgia

    Science.gov (United States)

    Tumanova, N.; Kakhoberashvili, S.; Omarashvili, V.; Tserodze, M.; Akubardia, D.

    2016-12-01

    Georgia, as a part of the Southern Caucasus, is tectonically active and structurally complex region. It is one of the most active segments of the Alpine-Himalayan collision belt. The deformation and the associated seismicity are due to the continent-continent collision between the Arabian and Eurasian plates. Seismic Monitoring of country and the quality of seismic data is the major tool for the rapid response policy, population safety, basic scientific research and in the end for the sustainable development of the country. National Seismic Network of Georgia has been developing since the end of 19th century. Digital era of the network started from 2003. Recently continuous data streams from 25 stations acquired and analyzed in the real time. Data is combined to calculate rapid location and magnitude for the earthquake. Information for the bigger events (Ml>=3.5) is simultaneously transferred to the website of the monitoring center and to the related governmental agencies. To improve rapid earthquake location and magnitude estimation the seismic network was enhanced by installing additional 7 new stations. Each new station is equipped with coupled Broadband and Strong Motion seismometers and permanent GPS system as well. To select the sites for the 7 new base stations, we used standard network optimization techniques. To choose the optimal sites for new stations we've taken into account geometry of the existed seismic network, topographic conditions of the site. For each site we studied local geology (Vs30 was mandatory for each site), local noise level and seismic vault construction parameters. Due to the country elevation, stations were installed in the high mountains, no accessible in winter due to the heavy snow conditions. To secure online data transmission we used satellite data transmission as well as cell data network coverage from the different local companies. As a result we've already have the improved earthquake location and event magnitudes. We

  4. Artificial seismic acceleration

    Science.gov (United States)

    Felzer, Karen R.; Page, Morgan T.; Michael, Andrew J.

    2015-01-01

    In their 2013 paper, Bouchon, Durand, Marsan, Karabulut, 3 and Schmittbuhl (BDMKS) claim to see significant accelerating seismicity before M 6.5 interplate mainshocks, but not before intraplate mainshocks, reflecting a preparatory process before large events. We concur with the finding of BDMKS that their interplate dataset has significantly more fore- shocks than their intraplate dataset; however, we disagree that the foreshocks are predictive of large events in particular. Acceleration in stacked foreshock sequences has been seen before and has been explained by the cascade model, in which earthquakes occasionally trigger aftershocks larger than themselves4. In this model, the time lags between the smaller mainshocks and larger aftershocks follow the inverse power law common to all aftershock sequences, creating an apparent acceleration when stacked (see Supplementary Information).

  5. Design, analysis, and seismic performance of a hypothetical seismically isolated bridge on legacy highway.

    Science.gov (United States)

    2011-01-01

    The need to maintain the functionality of critical transportation lifelines after a large seismic event motivates the : strategy to design certain bridges for performance standards beyond the minimum required by bridge design codes. : To design a bri...

  6. 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

    will be installed in several schools in the most important seismic areas (Vrancea, Dobrogea), vulnerable cities (Bucharest, Ploiesti, Iasi) or high populated places (Cluj, Sibiu, Timisoara, Zalău). All the elements of the seismic station are especially designed for educational purposes and can be operated independently by the students and teachers themselves. The first stage of ROEDUSEIS project was centered on the work of achievement of educational materials for all levels of pre-university education (kindergarten, primary, secondary and high school). A study of necessity preceded the achievement of educational materials. This was done through a set of questionnaires for teachers and students sent to participating schools. Their responses formed a feedback instrument for properly materials editing. The topics covered within educational materials include: seismicity (general principles, characteristics of Romanian seismicity, historical local events), structure of the Earth, measuring of earthquakes, seismic hazard and risk.

  7. Sediments of Lake Van - a high-resolution archive of changing climate, volcanic events and seismic activity in Eastern Anatolia for the last 500'000 yrs

    Science.gov (United States)

    Stockhecke, M.; Anselmetti, F. S.; Sturm, M.; Paleovan Scientific Party

    2012-04-01

    record. The sub-mm thin laminated intervals as recovered from different interglacials/interstadials stand out prominently against the more banded lithologies of the remaining sections. From 168 to 189 meters below the lake floor a unit of major irregularities and accumulation of deformations were identified as a large-scale mega-event deposit. It overlies a unit of carbonate-poor diatomaceous mud and a gravel-rich unit containing fresh-water gastropods (Bithynia) and mussels. The gravel is interpreted to have been deposited under beach-like conditions and reflects the early transgressive state of the lakés history. The distinct and great variability of sediment types is indicative of highly and rapidly changing depositional conditions forced by lake level and other climate-driven changes and by tectonic events over the past 500'000 years. The annual laminated intervals reflect strong seasonal fluctuations in particle fluxes to the lake bottom and bottom water anoxia. The onset/cessation of theses episodically occurring laminations represent threshold crossings indicative for abrupt changes of climate (e.g. Dansgaard-Oeschger cycles) and tectonic activities. The partly varved lacustrine record enables, for the first time, to reconstruct the environmental and climate conditions captured during several glacial/interglacial cycles at a mid-latitudinal continental realm.

  8. Seismicity at Jalisco-Nayarit Border, Mexico

    Science.gov (United States)

    Rutz, M.; Nunez-Cornu, F.; Camarena, M.; Trejo, E.; Reyes-Davila, G.; Suarez-Plasencia, C.

    2003-12-01

    Since 2002 a regional seismic network from Jalisco Civil Defense and University of Guadalalajara is monitoring seismicity at the northwest border of Jalisco block. With the installation of a seismic station on Ceboruco Volcano, by Nayarit Civil Defense, coverage of the network extends to east. Ceboruco Volcano is located on the Tepic-Zacoalco graben, the east border of Jalisco block, this allow us to begin to monitoring this area. The zone of Bahia de Banderas, between the north coast of Jalisco and south coast of Nayarit, probably on a tectonic triple point, is a region of high seismic potential. Activ tectonic structures and clusters in the zone of El Tuito and the Dam Cajon de Pe¤as have been identified. The seismicity in the north area of the bay is low, meanwhile in the south, where the bay is deeper, the seismicity level is higher with an East-West tendency. At the east, the Amatlan de Ca¤as-Ameca zone presents continue activity, here have been possible to locate events with local magnitude between 2 and 4. Tectonovolcanic events registred at Ceboruco station presents waveform with scattering. The seismic distribution of the coast of Jalisco shows parallel alignments to the trench throughout al the coast. Other perpendicular alignments to the coastline show active morphologic structures within the Jalisco block related to the subduction of the Rivera plate under the Jalisco block.

  9. Seismic risk perception test

    Science.gov (United States)

    Crescimbene, Massimo; La Longa, Federica; Camassi, Romano; Pino, Nicola Alessandro

    2013-04-01

    The perception of risks involves the process of collecting, selecting and interpreting signals about uncertain impacts of events, activities or technologies. In the natural sciences the term risk seems to be clearly defined, it means the probability distribution of adverse effects, but the everyday use of risk has different connotations (Renn, 2008). The two terms, hazards and risks, are often used interchangeably by the public. Knowledge, experience, values, attitudes and feelings all influence the thinking and judgement of people about the seriousness and acceptability of risks. Within the social sciences however the terminology of 'risk perception' has become the conventional standard (Slovic, 1987). The mental models and other psychological mechanisms which people use to judge risks (such as cognitive heuristics and risk images) are internalized through social and cultural learning and constantly moderated (reinforced, modified, amplified or attenuated) by media reports, peer influences and other communication processes (Morgan et al., 2001). Yet, a theory of risk perception that offers an integrative, as well as empirically valid, approach to understanding and explaining risk perception is still missing". To understand the perception of risk is necessary to consider several areas: social, psychological, cultural, and their interactions. Among the various research in an international context on the perception of natural hazards, it seemed promising the approach with the method of semantic differential (Osgood, C.E., Suci, G., & Tannenbaum, P. 1957, The measurement of meaning. Urbana, IL: University of Illinois Press). The test on seismic risk perception has been constructed by the method of the semantic differential. To compare opposite adjectives or terms has been used a Likert's scale to seven point. The test consists of an informative part and six sections respectively dedicated to: hazard; vulnerability (home and workplace); exposed value (with reference to

  10. Jalisco Regional Seismic Network (RESAJ)

    Science.gov (United States)

    Nunez-Cornu, F. J.; Suarez Plascencia, C.; Escudero, C. R.; Gomez, A.

    2011-12-01

    Many societies and their economies endure the disastrous consequences of destructive earthquakes. The Jalisco region is exposing to this natural hazard. Scientific knowledge constitutes the only way to avoid or at least to mitigate the negative effects of such events. Accordingly the study of geological and geophysical causes; structural, kinematics and dynamic characteristics; and destructive effects of such events is indispensable. The main objective of this project is to developed capability to monitor and to analyze the potential destructive earthquakes along the Jalisco region. This network will allows us to study the Rivera plate and the Jalisco block seismicity. Ten earthquakes greater than 7.4 occurred in the last 160 years, including the largest Mexican earthquake (8.2) producing considerable damage in the area. During this project we installed 20 telemetric seismic stations and we plan to deploy up to 30. The stations are component by 24 bit A/D, 6 channels Quanterra Q330-6 DAS, Lennartz Triaxial 1Hz wide band seismometer, a triaxial accelerometer episensor Model FBA ES-T from Kinemetrics and solar power supply. The data is transmitted using freewave Ethernet radios or wireless internet links. All stations will transmit the data in to the central at Puerto Vallarta where all data is processed using Antelope system to localize and make preliminary evaluations of the events in almost real time and stored for future research. This network will produce high quality data enough to evaluate the eight previously identified seismic zones along Jalisco.

  11. PARAMETERS OF KAMCHATKA SEISMICITY IN 2008

    Directory of Open Access Journals (Sweden)

    Vadim A. Saltykov

    2010-01-01

    Full Text Available The paper describes seismicity of Kamchatka for the period of 2008 and presents 2D distribution of background seismicity parameters calculated from data published in the Regional Catalogue of Kamchatka Earthquakes. Parameters under study are total released seismic energy, seismic activity A10, slope of recurrence graph γ, parameters of RTL, ΔS and Z-function methods, and clustering of earthquakes. Estimations of seismicity are obtained for a region bordered by latitude 50.5–56.5N, longitude 156E–167E, with depths to 300 km. Earthquakes of energy classes not less than 8.5 as per the Fedotov’s classification are considered. The total seismic energy released in 2008 is estimated. According to a function of annual seismic energy distribution, an amount of seismic energy released in 2008 was close to the median level (Fig. 1. Over 2/3 of the total amount of seismic energy released in 2008 resulted from three largest earthquakes (МW ≥ 5.9. About 5 percent of the total number of seismic events are comprised of grouped earthquakes, i.e. aftershocks and swarms. A schematic map of the largest earthquakes (МW ≥ 5.9 and grouped seismic events which occurred in 2008 is given in Fig. 2; their parameters are listed in Table 1. Grouped earthquakes are excluded from the catalogue. A map showing epicenters of independent earthquakes is given in Fig. 3. The slope of recurrence graph γ and seismic activity A10 is based on the Gutenberg-Richter law stating the fundamental property of seismic process. The recurrence graph slope is calculated from continuous exponential distribution of earthquakes by energy classes. Using γ is conditioned by observations that in some cases the slope of the recurrence graph decreases prior to a large earthquake. Activity A10 is calculated from the number of earthquakes N and recurrence graph slope γ. Average slopes of recurrence graph γ and seismic activity A10 for the area under study in 2008 are calculated; our

  12. Long term continuous radon monitoring in a seismically active area

    CERN Document Server

    Piersanti, A; Galli, G

    2015-01-01

    We present the results of a long term, continuous radon monitoring experiment started in April 2010 in a seismically active area, affected during the 2010-2013 data acquisition time window by an intense micro seismic activity and by several small seismic events. We employed both correlation and cross-correlation analyses in order to investigate possible relationship existing between the collected radon data, seismic events and meteorological parameters. Our results do not support the feasibility of a robust one-to-one association between the small magnitude earthquakes characterizing the local seismic activity and single radon measurement anomalies, but evidence significant correlation patterns between the spatio-temporal variations of seismic moment release and soil radon emanations, the latter being anyway dominantly modulated by meteorological parameters variations.

  13. Time dependent seismic hazard

    Science.gov (United States)

    Polidoro, B.; Iervolino, I.; Chioccarelli, E.; Giorgio, M.

    2012-04-01

    Probabilistic seismic hazard is usually computed trough a homogeneous Poisson process that even though it is a time-independent process it is widely used for its very convenient properties. However, when a single fault is of concern and/or the time scale is different from that of the long term, time-dependent processes are required. In this paper, different time-dependent models are reviewed with working examples. In fact, the Paganica fault (in central Italy) has been considered to compute both the probability of occurrence of at least one event in the lifespan of the structure, as well as the seismic hazard expressed in terms of probability of exceedance of an intensity value in a given time frame causing the collapse of the structure. Several models, well known or novel application to engineering hazard have been considered, limitation and issues in their applications are also discussed. The Brownian Passage Time (BPT) model is based on a stochastic modification of the deterministic stick-slip oscillator model for characteristic earthquakes; i.e., based on the addition of random perturbations (a Gaussian white noise) to the deterministic load path predicted by elastic rebound theory. This model assumes that the load state is at some ground level immediately after an event, increases steadly over time, reaches a failure threshold and relaxes instantaneously back to the ground level. For this model also a variable threshold has been considered to take into account the uncertainty of the threshold value. For the slip-predictable model it is assumed that the stress accumulates at a constant rate starting from some initial stress level. Stress is assumed to accumulate for a random period of time until an earthquake occurs. The size of the earthquake is governed by the stress release and it is a function of the elapsed time since the last event. In the time-predictable model stress buildup occurs at a constant rate until the accumulated stress reaches a threshold

  14. Moon meteoritic seismic hum: Steady state prediction

    Science.gov (United States)

    Lognonne, P.; Feuvre, M.L.; Johnson, C.L.; Weber, R.C.

    2009-01-01

    We use three different statistical models describing the frequency of meteoroid impacts on Earth to estimate the seismic background noise due to impacts on the lunar surface. Because of diffraction, seismic events on the Moon are typically characterized by long codas, lasting 1 h or more. We find that the small but frequent impacts generate seismic signals whose codas overlap in time, resulting in a permanent seismic noise that we term the "lunar hum" by analogy with the Earth's continuous seismic background seismic hum. We find that the Apollo era impact detection rates and amplitudes are well explained by a model that parameterizes (1) the net seismic impulse due to the impactor and resulting ejecta and (2) the effects of diffraction and attenuation. The formulation permits the calculation of a composite waveform at any point on the Moon due to simulated impacts at any epicentral distance. The root-mean-square amplitude of this waveform yields a background noise level that is about 100 times lower than the resolution of the Apollo long-period seismometers. At 2 s periods, this noise level is more than 1000 times lower than the low noise model prediction for Earth's microseismic noise. Sufficiently sensitive seismometers will allow the future detection of several impacts per day at body wave frequencies. Copyright 2009 by the American Geophysical Union.

  15. Seismotectonics and seismic Hazard map of Tunisia

    Science.gov (United States)

    Soumaya, Abdelkader; Ben Ayed, Noureddine; Khayati Ammar, Hayet; Kadri, Ali; Zargouni, Fouad; Ghanmi, Mohamed

    2016-04-01

    One natural hazard in Tunisia is caused by earthquakes and one way to measure the shaking risk is the probabilistic seismic-hazard map. The study of seismic hazard and risk assessment in Tunisia started in 1990 within the framework of the National Program for Assessment of Earthquake Risk. Because earthquakes are random events characterized by specific uncertainties, we used a probabilistic method to build the seismic hazard map of Tunisia. Probabilities were derived from the available seismic data and from results of neotectonic, geophysical and geological studies on the main active domains of Tunisia. This map displays earthquake ground motions for various probability levels across Tunisia and it is used in seismic provisions of building codes, insurance rate structures, risk assessment and other public management activities. The product is a seismotectonic map of Tunisia summarizing the available datasets (e.g., active fault, focal mechanism, instrumental and historical seismicity, peak ground acceleration). In addition, we elaborate some thematic seismic hazard maps that represent an important tool for the social and economic development.

  16. Seismotectonic and Seismic Hazard Map of Tunisia

    Science.gov (United States)

    Soumaya, A.; Ben Ayed, N.; Khayati Ammar, H.; Tayech, M.; Ghanmi, M.

    2016-12-01

    One natural hazard in Tunisia is caused by earthquakes and one way to measure the shaking risk is the probabilistic seismic-hazard map. The study of seismic hazard and risk assessment in Tunisia started in 1990 within the framework of the National Program for Assessment of Earthquake Risk. Because earthquakes are random events characterized by specific uncertainties, we used a probabilistic method to build the seismic hazard map of Tunisia. Probabilities were derived from the available seismic data and from results of neotectonic, geophysical and geological studies on the main active domains of Tunisia. This map displays earthquake ground motions for various probability levels across Tunisia and it is used in seismic provisions of building codes, insurance rate structures, risk assessment and other public management activities. The product is a seismotectonic map of Tunisia summarizing the available datasets (e.g., active fault, focal mechanism, instrumental and historical seismicity, peak ground acceleration). In addition, we elaborate some thematic seismic hazard maps that represent an important tool for the social and economic development.

  17. Robotization in Seismic Acquisition

    NARCIS (Netherlands)

    Blacquière, G.; Berkhout, A.J.

    2013-01-01

    The amount of sources and detectors in the seismic method follows "Moore’s Law of seismic data acquisition", i.e., it increases approximately by a factor of 10 every 10 years. Therefore automation is unavoidable, leading to robotization of seismic data acquisition. Recently, we introduced a new

  18. Seismic analysis for conceptual design of HCCR TBM-set

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Won, E-mail: dwlee@kaeri.re.kr [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Seong Dae; Jin, Hyung Gon; Lee, Eo Hwak; Kim, Suk-Kwon; Yoon, Jae Sung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Shin, Kyu In [Gentec Co., Daejeon, Republic of Korea (Korea, Republic of); Cho, Seungyon [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2016-11-01

    Highlights: • The seismic analysis of KO HCCR TBM-set are performed. • The seismic envents like SL-1, SL-2, and SMHV are selected and evaluated with FEM code (ANSYS). • The results of the stresses and deformations are confirmed to meet the design criteria. - Abstract: Using the conceptual design of the Korean helium cooled ceramic reflector (HCCR) test blanket module (TBM) including the TBM-shield for testing in ITER, a seismic analysis is performed. According to the ITER TBM port plug (TBM PP) system load specifications, seismic events are selected as SL-1 (seismic level-1), SL-2 (seismic level-2), and SMHV (seismes maximaux historiquement vraisemblables, Maximum Histroically Probable Earthquakes). In a modal analysis a total of 50 modes are obtained. Then, a spectra response analysis for each seismic event is carried out using ANSYS based on the modal analysis results. For each event, the obtained Tresca stress is evaluated to confirm the design integrity, by comparing the resulting stress to the design criteria. The Tresca strain and displacement are also estimated for the HCCR TBM-set. From the analysis, it was concluded that the maximum stresses by the seismic events meet the design criteria, and the displacements are lower than the designed gap from the TBM PP frame. The results are provided to a load combination analysis.

  19. Ground motion simulations for seismic stations in southern and eastern Romania and seismic hazard assessment

    Science.gov (United States)

    Pavel, Florin; Vacareanu, Radu

    2017-09-01

    This research focuses on the evaluation of soil conditions for seismic stations in southern and eastern Romania, their influence on stochastic finite-fault simulations, and the impact of using them on the seismic hazard assessment. First, the horizontal-to-vertical spectral ratios (HVSR) are evaluated using ground motions recorded in 32 seismic stations during small magnitude ( M W ≤ 6.0) Vrancea seismic events. Most of the seismic stations situated in the southern part of Romania exhibit multiple HVSR peaks over a broad period range. However, only the seismic stations in the eastern-most part of Romania have clear short-period predominant periods. Subsequently, stochastic finite-fault simulations are performed in order to evaluate the influence of the soil conditions on the ground motion amplitudes. The analyses show that the earthquake magnitude has a larger influence on the computed ground motion amplitudes for the short- and medium-period range, while the longer-period spectral ordinates tend to be influenced more by the soil conditions. Next, the impact of the previously evaluated soil conditions on the seismic hazard results for Romania is also investigated. The results reveal a significant impact of the soil conditions on the seismic hazard levels, especially for the sites characterized by long-period amplifications (sites situated mostly in southern Romania), and a less significant influence in the case of sites which have clear short predominant periods.

  20. Probabilistic seismic hazard assessment for Central Asia

    Directory of Open Access Journals (Sweden)

    Shahid Ullah

    2015-04-01

    Full Text Available Central Asia is one of the seismically most active regions in the world. Its complex seismicity due to the collision of the Eurasian and Indian plates has resulted in some of the world’s largest intra-plate events over history. The region is dominated by reverse faulting over strike slip and normal faulting events. The GSHAP project (1999, aiming at a hazard assessment on a global scale, indicated that the region of Central Asia is characterized by peak ground accelerations for 10% probability of exceedance in 50 years as high as 9 m/s2. In this study, carried out within the framework of the EMCA project (Earthquake Model Central Asia, the area source model and different kernel approaches are used for a probabilistic seismic hazard assessment (PSHA for Central Asia. The seismic hazard is assessed considering shallow (depth < 50 km seismicity only and employs an updated (with respect to previous projects earthquake catalog for the region. The seismic hazard is calculated in terms of macroseismic intensity (MSK-64, intended to be used for the seismic risk maps of the region. The hazard maps, shown in terms of 10% probability of exceedance in 50 years, are derived by using the OpenQuake software [Pagani et al. 2014], which is an open source software tool developed by the GEM (Global Earthquake Model foundation. The maximum hazard observed in the region reaches an intensity of around 8 in southern Tien Shan for 475 years mean return period. The maximum hazard estimated for some of the cities in the region, Bishkek, Dushanbe, Tashkent and Almaty, is between 7 and 8 (7-8, 8.0, 7.0 and 8.0 macroseismic Intensity, respectively, for 475 years mean return period, using different approaches. The results of different methods for assessing the level of seismic hazard are compared and their underlying methodologies are discussed.

  1. SEISMIC DISTRESS AND PROTECTION OF FLEXIBLE MEMBRANE LINERS OF SOLID WASTE LANDFILLS

    DEFF Research Database (Denmark)

    Zania, Varvara; Tsompanakis, Yiannis; Psarropoulos, Prodromos

    2011-01-01

    Seismic distress of solid waste landfills may result from any of the two consequences of a seismic event: (a) the transient ground deformation related to seismic wave propagation, (b) the permanent ground deformation caused by abrupt fault dislocation. Design provisions for solid waste landfills...

  2. Seismicity pattern before the 1980 Irpinia, Italy, earthquake

    Energy Technology Data Exchange (ETDEWEB)

    Suhadolc, P.; Panza, G.F. (Istituto di Geodesia e Geofisica, Universita di Trieste (Italy))

    Seismicity patterns and precursors before the 11/23/80 Irpinia, Italy, earthquake are searched for in the ENEL-CNEN Italian earthquake catalogue. By subdividing the region into several seismogenetic areas, some well defined seismicity features are found, which might be taken as precursory to the 1980 event. Features already pointed out as precursory in the literature are also contained in the space-time seismicity pattern. Prediction of approximate location where the main rupture is bound to occur is permitted, by grouping the seismogenetic areas into a seismically homogeneous region.

  3. Characterization of the seismic environment at the Sanford Underground Laboratory, South Dakota

    Energy Technology Data Exchange (ETDEWEB)

    Harms, J; Dorsher, S; Kandhasamy, S; Mandic, V [University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Acernese, F; Barone, F [Universita degli Studi di Salerno, Fisciano (Saudi Arabia) (Italy); Bartos, I; Marka, S [Columbia University, New York, NY 10027 (United States); Beker, M; Van den Brand, J F J; Rabeling, D S [Nikhef, National Institute for Subatomic Physics, Science Park 105, 1098 XG Amsterdam (Netherlands); Christensen, N; Coughlin, M [Carleton College, Northfield, MN 55057 (United States); DeSalvo, R [California Institute of Technology, Pasadena, CA 91125 (United States); Heise, J; Trancynger, T [Sanford Underground Laboratory, 630 East Summit Street, Lead, SD 57754 (United States); Mueller, G [University of Florida, Gainesville, FL 32611 (United States); Naticchioni, L [Department of Physics, University of Rome ' Sapienza' , P.le Aldo Moro 2, 00185 Rome (Italy); O' Keefe, T [Saint Louis University, 3450 Lindell Blvd., St. Louis, MO 63103 (United States); Sajeva, A, E-mail: janosch@caltech.ed [Dipartimento di Fisica ' Enrico Fermi' , Universita di Pisa, Largo Bruno Pontecorvo, Pisa (Italy)

    2010-11-21

    An array of seismometers is being developed at the Sanford Underground Laboratory, the former Homestake mine, in South Dakota to study the properties of underground seismic fields and Newtonian noise, and to investigate the possible advantages of constructing a third-generation gravitational-wave detector underground. Seismic data were analyzed to characterize seismic noise and disturbances. External databases were used to identify sources of seismic waves: ocean-wave data to identify sources of oceanic microseisms and surface wind-speed data to investigate correlations with seismic motion as a function of depth. In addition, sources of events contributing to the spectrum at higher frequencies are characterized by studying the variation of event rates over the course of a day. Long-term observations of spectral variations provide further insight into the nature of seismic sources. Seismic spectra at three different depths are compared, establishing the 4100 ft level as a world-class low seismic-noise environment.

  4. Autonomous detection of calving-related seismicity at Kronebreen, Svalbard

    Directory of Open Access Journals (Sweden)

    A. Köhler

    2012-03-01

    Full Text Available We detect and cluster waveforms of seismic signals recorded close to the calving front of Kronebreen, Svalbard, to identify glacier-related seismic events and to investigate their relation to calving processes. Single-channel geophone data recorded over several months in 2009 and 2010 are combined with eleven days of direct visual observations of the glacier front. We apply a processing scheme which combines conventional seismic event detection using a sensitive trigger algorithm and unsupervised clustering of all detected signals based on their waveform characteristics by means of Self-Organizing Maps (SOMs. About 10% of the directly observed calving events close to the geophone (<1 km can be correlated with seismic detections. We are able to distinguish between false detections, instrumental artifacts, and three classes of signals which are, with different degrees of uncertainty, emitted by calving or glacier activity in general. By extrapolating the interpretation of seismic event classes beyond the time period of visual observations, the temporal distribution of glacier-related events shows an increase in event rate in autumn, particularly for the class which is related to iceberg calving. Using the seismic event distribution in this class as a proxy for the calving rate and measurements of glacier velocity and glacier front position, we discuss the possible relationship between glacier dynamics and calving processes at Kronebreen.

  5. Features, Events, and Processes: Disruptive Events

    Energy Technology Data Exchange (ETDEWEB)

    J. King

    2004-03-31

    The primary purpose of this analysis is to evaluate seismic- and igneous-related features, events, and processes (FEPs). These FEPs represent areas of natural system processes that have the potential to produce disruptive events (DE) that could impact repository performance and are related to the geologic processes of tectonism, structural deformation, seismicity, and igneous activity. Collectively, they are referred to as the DE FEPs. This evaluation determines which of the DE FEPs are excluded from modeling used to support the total system performance assessment for license application (TSPA-LA). The evaluation is based on the data and results presented in supporting analysis reports, model reports, technical information, or corroborative documents that are cited in the individual FEP discussions in Section 6.2 of this analysis report.

  6. Seismicity and Design Codes in Chile: Characteristic Features and a Comparison with Some of the Provisions of the Romanian Seismic Design Code

    OpenAIRE

    Ene, Diana; Craifaleanu, Iolanda-Gabriela

    2010-01-01

    A brief history and the characteristics of the seismic region and events in Chile reveal interesting indices in understanding the present day Chilean seismic design code. The paper points out some of the most important prescriptions in the Chilean code that could have led to the relatively reduced number of casualties at the seismic event on February 27th, 2010. By comparing the Chilean code to the Romanian one, the goal is to underline the differences and the similarities regarding both the ...

  7. Advanced Seismic Probabilistic Risk Assessment Demonstration Project Plan

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Justin [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-09-01

    Idaho National Laboratories (INL) has an ongoing research and development (R&D) project to remove excess conservatism from seismic probabilistic risk assessments (SPRA) calculations. These risk calculations should focus on providing best estimate results, and associated insights, for evaluation and decision-making. This report presents a plan for improving our current traditional SPRA process using a seismic event recorded at a nuclear power plant site, with known outcomes, to improve the decision making process. SPRAs are intended to provide best estimates of the various combinations of structural and equipment failures that can lead to a seismic induced core damage event. However, in general this approach has been conservative, and potentially masks other important events (for instance, it was not the seismic motions that caused the Fukushima core melt events, but the tsunami ingress into the facility).

  8. Temporal Delineation and Quantification of Short Term Clustered Mining Seismicity

    Science.gov (United States)

    Woodward, Kyle; Wesseloo, Johan; Potvin, Yves

    2017-07-01

    The assessment of the temporal characteristics of seismicity is fundamental to understanding and quantifying the seismic hazard associated with mining, the effectiveness of strategies and tactics used to manage seismic hazard, and the relationship between seismicity and changes to the mining environment. This article aims to improve the accuracy and precision in which the temporal dimension of seismic responses can be quantified and delineated. We present a review and discussion on the occurrence of time-dependent mining seismicity with a specific focus on temporal modelling and the modified Omori law (MOL). This forms the basis for the development of a simple weighted metric that allows for the consistent temporal delineation and quantification of a seismic response. The optimisation of this metric allows for the selection of the most appropriate modelling interval given the temporal attributes of time-dependent mining seismicity. We evaluate the performance weighted metric for the modelling of a synthetic seismic dataset. This assessment shows that seismic responses can be quantified and delineated by the MOL, with reasonable accuracy and precision, when the modelling is optimised by evaluating the weighted MLE metric. Furthermore, this assessment highlights that decreased weighted MLE metric performance can be expected if there is a lack of contrast between the temporal characteristics of events associated with different processes.

  9. First Quarter Hanford Seismic Report for Fiscal Year 2011

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-03-31

    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. The Hanford Seismic Network recorded 16 local earthquakes during the first quarter of FY 2011. Six earthquakes were located at shallow depths (less than 4 km), seven earthquakes at intermediate depths (between 4 and 9 km), most likely in the pre-basalt sediments, and three earthquakes were located at depths greater than 9 km, within the basement. Geographically, thirteen earthquakes were located in known swarm areas and three earthquakes were classified as random events. The highest magnitude event (1.8 Mc) was recorded on October 19, 2010 at depth 17.5 km with epicenter located near the Yakima River between the Rattlesnake Mountain and Horse Heaven Hills swarm areas.

  10. Use of moment independent importance measures in the framework of seismic fragility analysis

    OpenAIRE

    Zentner, I.; Borgonovo, E.; Pellegri, A.; Tarantola, S.

    2010-01-01

    In the nuclear industry, the seismic probabilistic risk assessment (PRA) has become the most commonly used methodology for evaluating the seismic risk of nuclear plants. In this framework, fragility curves express the conditional probability of failure of a structure or component for a given seismic input motion parameter value. The failure probability of a component due to a seismic event is obtained by integrating the conditional probability of failure (fragility) with respect to s...

  11. 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.

  12. The 11 May 2011 Lorca earthquake and the seismicity of the region; El terremoto de Lorca de 11 de mayo de 2011 y la sismicidad de la region

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Solares, J. M.; Cantavella Nadal, J. V.; Canas Rodriguez, L.; Valero Zornosa, J. F.

    2012-07-01

    Lorca 2011 seismic series is described presenting its location parameters and the seismic moment tensor of its main events. We analyse its features by means of the whole seismic sequence temporal and spatial distribution, and we compare it with previous seismic series in the same region. Macro seismic data and PGA values gathered in this area are summarized in this paper. In addition, after a thorough revision of the regional seismicity for both historic and instrumental events, we make some modifications in the seismic catalogue. (Author) 32 refs.

  13. A GIS approach to seismic risk assessment with an application to mining-related seismicity in Johannesburg, South Africa

    Science.gov (United States)

    Liebenberg, Keagen; Smit, Ansie; Coetzee, Serena; Kijko, Andrzej

    2017-08-01

    The majority of seismic activity in South Africa is related to extensive mining operations, usually in close proximity to densely populated areas where a relatively weak seismic event could cause damage. Despite a significant decrease in mining operations in the Witwatersrand area, the number of seismic events appears to be increasing and is attributed to the acid mine drainage problem. The increased seismicity is raising concern amongst disaster management centres and in the insurance industry. A better understanding is required of the vulnerability and the size of the potential loss of people and infrastructure in densely populated Johannesburg and its surrounding areas. Results of a deterministic seismic risk, vulnerability, and loss assessment are presented by making use of a geographic information system (GIS). The results illustrate the benefits of using GIS and contribute to a better understanding of the risk, which can assist in improving disaster preparedness.

  14. Induced seismicity associated with Enhanced Geothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Majer, Ernest L. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 90-R1116, Berkeley, CA 94720 (United States); Baria, Roy [MIL-TECH UK Ltd., 62 Rosewood Way, West End, Woking, Surrey GU24 9PF (United Kingdom); Stark, Mitch [Calpine Corp., 10350 Socrates Mine Road, Middletown, CA 95461 (United States); Oates, Stephen [Shell International Exploration and Production, Kesslerpark 1, 2288-GS Rijswijk-ZH (Netherlands); Bommer, Julian [Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Smith, Bill [Northern California Power Agency, Middletown, P.O. Box 663, Middletown, CA 95461 (United States); Asanuma, Hiroshi [Graduate School of Environmental Studies, Tohoku University, 980-8579 Sendai (Japan)

    2007-06-15

    Enhanced Geothermal Systems (EGS) have the potential to make a significant contribution to the world energy inventory. One controversial issue associated with EGS, however, is the impact of induced seismicity or microseismicity, which has been the cause of delays and threatened cancellation of at least two EGS projects worldwide. Although microseismicity has in fact had few (or no) adverse physical effects on operations or on surrounding communities, there remains public concern over the amount and magnitude of the seismicity associated with current and future EGS operations. The primary objectives of this paper are to present an up-to-date review of what is already known about the seismicity induced during the creation and operation of EGS, and of the gaps in our knowledge that, once addressed, should lead to an improved understanding of the mechanisms generating the events. Several case histories also illustrate a number of technical and public acceptance issues. We conclude that EGS-induced seismicity need not pose a threat to the development of geothermal energy resources if site selection is carried out properly, community issues are handled adequately and operators understand the underlying mechanisms causing the events. Induced seismicity could indeed prove beneficial, in that it can be used to monitor the effectiveness of EGS operations and shed light on geothermal reservoir processes. (author)

  15. Seismic Imaging of Open Subsurface Fractures

    Science.gov (United States)

    Myers, S. C.; Pitarka, A.; Matzel, E.; Aguiar, A. C.

    2015-12-01

    Injection of high-pressure fluid into the subsurface is proven to stimulate geothermal, oil, and gas production by opening cracks that increase permeability. The effectiveness of increasing permeability by high-pressure injection has been revolutionized by the introduction of "proppants" into the injected fluid to keep cracks open after the pressure of the stimulation activity ends. The network of fractures produced during stimulation is most commonly inferred by the location of micro-earthquakes. However, existing (closed) fractures may open aseismically, so the whole fracture network may not be imaged by micro-seismic locations alone. Further, whether all new fractures remain open and for how long remains unclear. Open cracks, even fluid-filled cracks, scatter seismic waves because traction forces are not transmitted across the gap. Numerical simulation confirms that an open crack with dimensions on the order of 10 meters can scatter enough seismic energy to change the coda of seismic signals. Our simulations show that changes in seismic coda due to newly opened fractures are only a few percent of peak seismogram amplitudes, making signals from open cracks difficult to identify. We are developing advanced signal processing methods to identify candidate signals that originate from open cracks. These methods are based on differencing seismograms that are recorded before and after high-pressure fluid injection events to identify changes in the coda. The origins of candidate signals are located using time-reversal techniques to determine if the signals are indeed associated with a coherent structure. The source of scattered energy is compared to micro-seismic event locations to determine whether cracks opened seismically or aseismically. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-675612.

  16. Identification of seismic precursors before large earthquakes: Decelerating and accelerating seismic patterns

    Science.gov (United States)

    Papadimitriou, Panayotis

    2008-04-01

    A useful way of understanding both seismotectonic processes and earthquake prediction research is to conceive seismic patterns as a function of space and time. The present work investigates seismic precursors before the occurrence of an earthquake. It does so by means of a methodology designed to study spatiotemporal characteristics of seismicity in a selected area. This methodology is based on two phenomena: the decelerating moment release (DMR) and the accelerating moment release (AMR), as they occur within a period ranging from several months to a few years before the oncoming event. The combination of these two seismic sequences leads to the proposed decelerating-accelerating moment release (DAMR) earthquake sequence, which appears as the last stage of loading in the earthquake cycle. This seismic activity appears as a foreshock sequence and can be supported by the stress accumulation model (SAM). The DAMR earthquake sequence constitutes a double seismic precursor identified in space and time before the occurrence of an earthquake and can be used to improve seismic hazard assessment research. In this study, the developed methodology is applied to the data of the 1989 Loma Prieta (California), the 1995 Kobe (Japan), and the 2003 Lefkada (Greece) earthquakes. The last part of this study focuses on the application of the methodology to the Ionian Sea (western Greece) and forecasts two earthquakes in that area.

  17. Ischia Island: Historical Seismicity and Dynamics

    Science.gov (United States)

    Carlino, S.; Cubellis, E.; Iannuzzi, R.; Luongo, G.; Obrizzo, F.

    2003-04-01

    The seismic energy release in volcanic areas is a complex process and the island of Ischia provides a significant scenario of historical seismicity. This is characterized by the occurence of earthquakes with low energy and high intensity. Information on the seismicity of the island spans about eight centuries, starting from 1228. With regard to effects, the most recent earthquake of 1883 is extensively documented both in the literature and unpublished sources. The earthquake caused 2333 deaths and the destruction of the historical and environmental heritage of some areas of the island. The most severe damage occurred in Casamicciola. This event, which was the first great catastrophe after the unification of Italy in the 1860s (Imax = XI degree MCS), represents an important date in the prevention of natural disasters, in that it was after this earthquake that the first Seismic Safety Act in Italy was passed by which lower risk zones were identified for new settlements. Thanks to such detailed analysis, reliable modelling of the seismic source was also obtained. The historical data onwards makes it possible to identify the area of the epicenter of all known earthquakes as the northern slope of Monte Epomeo, while analysis of the effects of earthquakes and the geological structures allows us to evaluate the stress fields that generate the earthquakes. In a volcanic area, interpretation of the mechanisms of release and propagation of seismic energy is made even more complex as the stress field that acts at a regional level is compounded by that generated from migration of magmatic masses towards the surface, as well as the rheologic properties of the rocks dependent on the high geothermic gradient. Such structural and dynamic conditions make the island of Ischia a seismic area of considerable interest. It would appear necessary to evaluate the expected damage caused by a new event linked to the renewal of dynamics of the island, where high population density and the

  18. Seismicity at Baru Volcano, Western Panama, Panama

    Science.gov (United States)

    Camacho, E.; Novelo-Casanova, D. A.; Tapia, A.; Rodriguez, A.

    2008-12-01

    The Baru volcano in Western Panama (8.808°N, 82.543°W) is a 3,475 m high strato volcano that lies at about 50 km from the Costa Rican border. The last major eruptive event at this volcano occurred c.1550 AD and no further eruptive activity from that time is known. Since the 1930´s, approximately every 30 years a series of seismic swarms take place in the surroundings of the volcanic edifice. Theses swarms last several weeks alarming the population who lives near the volcano. The last of these episodes occurred on May 2006 and lasted one and a half months. More than 20,000 people live adjacent to the volcano and any future eruption has the potential to be very dangerous. In June 2007, a digital seismic monitoring network of ten stations, linked via internet, was installed around the volcano in a collaborative project between the University of Panama and the Panamanian Government. The seismic data acquisition at the sites is performed using LINUX-SEISLOG and the events are recorded by four servers at different locations using the Earth Worm system. In this work we analyze the characteristics of the volcano seismicity recorded from May 4th, 2006 to July 31st, 2008 by at least 4 stations and located at about 15 km from the summit. To determine the seismic parameters, we tested several crustal velocity models and used the seismic analysis software package SEISAN. Our final velocity model was determined using seismic data for the first four km obtained from a temporal seismic network deployed in 1981 by the British Geological Survey (BGS) as part of geothermal studies conducted at Cerro Pando, Western Panama Highlands. Our results indicate that all the events recorded in the quadrant 8.6-9.0°N and 82.2-82.7°W are located in the depth range of 0.1 to 8 km. Cross sections show vertical alignments of hypocenters below the summit although most of the seismicity is concentrated in its eastern flank reaching the town of Boquete. All the calculated focal mechanisms are of

  19. Evaluation of the seismic hazard for 20 cities in Romania using Monte Carlo based simulations

    Science.gov (United States)

    Pavel, Florin; Vacareanu, Radu

    2017-07-01

    This work focuses on the evaluation of the seismic hazard for Romania using earthquake catalogues generated by a Monte Carlo approach. The seismicity of Romania can be attributed to the Vrancea intermediate-depth seismic source and to 13 other crustal seismic sources. The recurrence times of large magnitude seismic events (both crustal and subcrustal), as well as the moment release rates are computed using simulated earthquake catalogues. The results show that the largest contribution to the overall moment release for the crustal seismic sources is from the seismic regions in Bulgaria, while the seismic regions in Romania contribute less than 5% of the overall moment release. In addition, the computations show that the moment release rate for the Vrancea subcrustal seismic source is about ten times larger than that of all the crustal seismic sources. Finally, the Monte Carlo approach is used to evaluate the seismic hazard for 20 cities in Romania with populations larger than 100,000 inhabitants. The results show some differences between the seismic hazard values obtained through Monte-Carlo simulation and those in the Romanian seismic design code P100-1/2013, notably for cities situated in the western part of Romania that are influenced by local crustal seismic sources.

  20. Seismic Risk Assessment for the Kyrgyz Republic

    Science.gov (United States)

    Pittore, Massimiliano; Sousa, Luis; Grant, Damian; Fleming, Kevin; Parolai, Stefano; Fourniadis, Yannis; Free, Matthew; Moldobekov, Bolot; Takeuchi, Ko

    2017-04-01

    The Kyrgyz Republic is one of the most socially and economically dynamic countries in Central Asia, and one of the most endangered by earthquake hazard in the region. In order to support the government of the Kyrgyz Republic in the development of a country-level Disaster Risk Reduction strategy, a comprehensive seismic risk study has been developed with the support of the World Bank. As part of this project, state-of-the-art hazard, exposure and vulnerability models have been developed and combined into the assessment of direct physical and economic risk on residential, educational and transportation infrastructure. The seismic hazard has been modelled with three different approaches, in order to provide a comprehensive overview of the possible consequences. A probabilistic seismic hazard assessment (PSHA) approach has been used to quantitatively evaluate the distribution of expected ground shaking intensity, as constrained by the compiled earthquake catalogue and associated seismic source model. A set of specific seismic scenarios based on events generated from known fault systems have been also considered, in order to provide insight on the expected consequences in case of strong events in proximity of densely inhabited areas. Furthermore, long-span catalogues of events have been generated stochastically and employed in the probabilistic analysis of expected losses over the territory of the Kyrgyz Republic. Damage and risk estimates have been computed by using an exposure model recently developed for the country, combined with the assignment of suitable fragility/vulnerability models. The risk estimation has been carried out with spatial aggregation at the district (rayon) level. The obtained results confirm the high level of seismic risk throughout the country, also pinpointing the location of several risk hotspots, particularly in the southern districts, in correspondence with the Ferghana valley. The outcome of this project will further support the local

  1. 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.

  2. Seismic monitoring of Central Asia territory in KNDC.

    Science.gov (United States)

    Mukambayev, Aidyn; Mikhailova, Natalia

    2015-04-01

    The Central Asia territory includes the territory of five post-Soviet countries: Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. Every country has its own independent network of seismic observations and Data Processing Center aimed at every day seismic monitoring of one country territory. However, seismic hazard of Central Asia territory is stipulated by one geodynamic system that generates simultaneous large earthquakes on the territory of different countries. Thus, it is necessary to observe seismic situation for the whole region for emergency situations and for compilation of joint seismic bulletins of Central Asia region. A new contemporary network of seismic observations operated by the Institute of Geophysical Researches has been installed in Kazakhstan during last 15 years. Mainly, these are seismic arrays located throughout the country perimeter. The arrays were constructed under support of the CTBTO, and AFTAC. There are also IRIS and CAREMON stations. All data arrive to KNDC (Kazakhstan National Data Center) in real time mode. In addition, KNDC receives data in real time from stations Zalesovo (Russia), Alibek (Turkmenistan), Ala-Archa and Tokmak (Kyrgyzstan). Arrival times in the form of tables are received with 24-hours delay from almost 20 Kazakhstan stations belonging to SEME MES RK. This observation system allows monitoring the Central Asian seismicity by earthquakes with representative magnitude more than 3.5. In some regions, the events with magnitude 1.5 are recorded. As result, different products with different operativity are created for Central Asia territory: -bulletin of urgent alerts; -automatic seismic bulletin; -interactive seismic bulletin; -joint seismic operative bulletin by data arrived on-line and in table form. After that, in retrospective mode, the events nature is identified to discriminate mining explosions (up to 4000 per year) and natural earthquakes (up to 15000 per year). The results are available at KNDC web

  3. Imaging Seismic Reflections

    NARCIS (Netherlands)

    op 't Root, T.J.P.M.; Op 't Root, Timotheus Johannes Petrus Maria

    2011-01-01

    The goal of reflection seismic imaging is making images of the Earth subsurface using surface measurements of reflected seismic waves. Besides the position and orientation of subsurface reflecting interfaces it is a challenge to recover the size or amplitude of the discontinuities. We investigate

  4. The INGV seismic monitoring system: activities during the first month of the 2016 Amatrice seismic sequence.

    Science.gov (United States)

    Scognamiglio, L.; Margheriti, L.; Moretti, M.; Pintore, S.

    2016-12-01

    At 01:36:32 UTC on August 24, 2016 an earthquake of ML=6.0 occurred in Central Italy, near Amatrice village; 21 s after the origin time, the first automatic location became available while the first magnitude estimate followed 47s after. The INGV seismologists on duty provided the alert to the Italian Civil Protection Department and thereby triggered the seismic emergency protocol In the hours after the earthquake, hundreds of events were recorded by the Italian Seismic Network of the INGV. SISMIKO, the coordinating body of the emergency seismic network, was activated few minutes after the mainshock. The main goal of this emergency group is to install temporary dense seismic network integrated with the existing permanent networks in the epicentral area to better constrain the aftershock hypocenters. From August the 24th to the 30th, SISMIKO deployed 18 seismic stations, generally six components (equipped with both seismometer and accelerometer), 13 of which were transmitting in real-time to the INGV seismic surveillance room in Rome. All data acquired are available at the European Integrated Data Archive (EIDA). The seismic sequence in the first month generated thousands of earthquakes which were processed and detected by the INGV automated localization system. We analyzed the performance of this system. Hundreds of those events were located by seismologists on shifts, the others were left to be analyzed by the Bollettino Sismico Italiano (BSI). The procedures of the BSI revise and integrate all available data. This allows for a better constrained location and for a more realistic hypocentral depth estimation. The first eight hours of August 24th were the most critical for the INGV surveillance room. Data recorded in these hours were carefully re-analyzed by BSI operators and the number of located events increased from 133 to 408, while the magnitude of completeness dropped significantly from about 3.5 to 2.7.

  5. Time-Space Evolution of Seismic Strain Release in the Area Shocked by the August 24-October 30 Central Italy Seismic Sequence

    Science.gov (United States)

    Barani, Simone; Mascandola, Claudia; Serpelloni, Enrico; Ferretti, Gabriele; Massa, Marco; Spallarossa, Daniele

    2017-05-01

    In this study, we analyze the space-time evolution of the seismic strain release in the area shocked by the still ongoing Italian Central Apennines seismic crisis started on August 24, 2016 and culminated with the October 30 main shock of M w 6.5. Specifically, we examine the variation in time and space of the seismic strain release rate with the aim of identifying the presence of peculiar seismicity patterns, such as seismic gaps, according to the seismic cycle theory. To this end, seismic strain rates are checked for consistency with strain rates from GPS measurements to possibly adjust them for missing events due to limited seismic catalog extension or incompleteness at large magnitudes. Our results has revealed that the seismic crisis followed a long-term quiescence of about 310 years, characterized by the absence of M6.5+ earthquakes, and marked by an almost steady release of seismic deformation. Such temporal gap started after the occurrence of two nearby strong events in 1703 (Valnerina and L'Aquila earthquakes with magnitudes of 6.9 and 6.7, respectively) and terminated with the beginning of the current Central Apennines seismic crisis.

  6. Numerical modeling of tunneling-induced seismicity

    Science.gov (United States)

    Rinaldi, Antonio Pio; Urpi, Luca

    2017-04-01

    Removal of rock mass in mining environment has been associated since long-time with seismic event of magnitude 3 and above, with the potential to cause damage to the infrastructures or even loss of human life. Although with similarities with mining, relatively unknown up to now are seismic events induced by tunneling. However with modern mechanized tunneling techniques, making possible to digging deeper and longer underground infrastructure, the risk is not negligible. As an example, the excavation of the 57km long Gotthard Base Tunnel has been associated more than hundred seismic events, with the largest one having magnitude of ML 2.4, damaging the tunnel infrastructures. For future scenario of deep geological storage of nuclear waste, tunneling will constitute the primary activity during site construction. Hence, it will be crucial to understand the risk associated with the underground construction operation that can reactivate seismogenic features nearby the future location of emplacement tunnels. Here we present numerical simulation aimed at understanding the potential for inducing seismicity during tunnel construction. The stress changes and their evolution during the excavation are evaluated with a finite element solver (FLAC3d). A strain-softening friction model is then used to simulate the occurrence of a sudden slip on a fault zone (if critical conditions for reactivation are reached). We also present a sensitivity analysis of the potential for inducing different seismic events by different tunnel sizes at varying distance from a nearby failure plane, with the final purpose of evaluating safety of a potential nuclear repository site on the short- and long-term.

  7. Detecting and Monitoring for Induced Seismicity without a Local Seismic Network: Application to the Youngstown, Ohio Induced Seismic Sequence

    Science.gov (United States)

    Holtkamp, S. G.; Brudzinski, M. R.; Currie, B. S.

    2013-12-01

    From March to December 2011, the Ohio Department of Natural Resources Ohio Seismic Network (ODNR OSN) recorded 11 earthquakes in Youngstown, OH. Pumping stopped after a local seismic network was installed in December and showed the earthquakes were nucleating near a nearby wastewater injection well. Unfortunately, 11 events identified by ODNR plus the local data represent a limited characterization of the sequence, making it difficult to confirm a causal relationship between injection and the earthquakes. This is a limitation of traditional seismic techniques, which required an earthquake to be M>~2.0 to be identified by ODNR before the local deployment. While local seismic deployments can provide adequate resolution to test triggering hypotheses, they suffer from two disadvantages: (1) these deployments are costly and scientifically focused, and (2) they only monitor seismicity after they are installed, and so are unable to characterize the beginning of the seismic sequence. Since there are over 200,000 wells associated with energy technologies in the US, it is not reasonable to install or expect local seismic observational capabilities with each potential case of induced seismicity. To address this limitation, we have developed a multiple station template matching (waveform cross correlation) algorithm, which is able to detect events ~10x smaller than traditional techniques, utilizing regional broadband seismometers located within 200km of the earthquakes. With this technique, we detect ~280 earthquakes in the Youngstown earthquake sequence, allowing us to test the correlation between seismicity and injection. We find that the earthquakes started two weeks after injection began and ended 2 weeks after injection ended. Our improved catalog shows that the rate of earthquakes closely follows the injection history, with a gradual rate increase at the beginning of the sequence and an abrupt reduction in earthquake rate after injection ceased. A combination of relative

  8. Seismic monitoring of a rock slope Åknes, Norway: time-reversal localization of seismic activity

    Science.gov (United States)

    Fischer, Tomas; Roth, Michael; Kühn, Daniela

    2014-05-01

    The Åknes rockslide in western Norway is characterized by a steady movement of a rock mass of about 1 km2 area with yearly rate of few centimeters. A seismic network consisting of 8 three-component geophones is used to monitor the slope. Tens to hundreds of local and distant seismic events are recorded daily. The local seismic events show a variety of waveforms, both with abrupt and emergent onsets, including events related to the rock-slide activity, rolling stones and snow avalanches. This makes, along with the relatively low frequency content of the waveforms, the standard processing in the form of arrival time measurement rather difficult. We present a method of time reversal stacking of signal envelopes and their STA/LTA ratios, which allows for identification and approximate location of the local seismic events. The method was successfully tested by locating two types of ground-truth data: surface blasts carried out during a seismic survey and a block rock collapse occurring in September 2012. The test proved the ability of the method to determine the approximate position of microseismic events, which enables to distinguish among several foci of the rock slide activity. Application of the method to 8 years of recorded data showed a continuous seismic activity that is concentrated at the centre and at the eastern edge of the monitored area. A seasonal increase of activity is observed during spring, which is probably related to the snow-melt period.

  9. Seismic hazard versus design accelerograms

    Directory of Open Access Journals (Sweden)

    Horea SANDI

    2012-07-01

    Full Text Available The developments presented herewith arise from the legitimate wish and task of structural engineers of performing consistent analyses of risk and safety for works located in seismic regions. The paper adopts a probabilistic viewpoint, or philosophy. The starting point of this discussion is based on well – established approaches, while at the same time addressing specific research problems that could represent the task of the future, even if not an immediate one. The main topics are as follows: a brief view of (3-rd level probabilistic safety and risk analysis, based on simplifying assumptions, which serves as a starting point for subsequent developments; a review of seismic action and hazard representation from two perspectives: ground motion during one event (advocating design accelerograms and stochastic models and recurrence of successive events (considering, after the usual 1D approach, a generalized approach based on the consideration of a multi-dimensional space of characteristic action parameters; the development of a multi-dimensional stochastic model of ground motion (basically for a half-space consisting of successive horizontal homogeneous layers; a brief discussion of alternative possible objectives of engineering safety analyses.

  10. A study on seismicity and seismic hazard for Karnataka State

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 121; Issue 2. A study on seismicity and seismic hazard for Karnataka State. T G Sitharam Naveen ... This paper presents a detailed study on the seismic pattern of the state of Karnataka and also quantifies the seismic hazard for the entire state. In the present work, ...

  11. Delineation of seismic source zones based on seismicity parameters ...

    Indian Academy of Sciences (India)

    The delineation of seismic source zones plays an important role in the evaluation of seismic hazard. In most of the studies the seismic source delineation is done based on geological features. In the present study, an attempt has been made to delineate seismic source zones in the study area (south India) based on the ...

  12. Forecasting induced seismicity rate and Mmax using calibrated numerical models

    Science.gov (United States)

    Dempsey, D.; Suckale, J.

    2016-12-01

    At Groningen, The Netherlands, several decades of induced seismicity from gas extraction has culminated in a M 3.6 event (mid 2012). From a public safety and commercial perspective, it is desirable to anticipate future seismicity outcomes at Groningen. One way to quantify earthquake risk is Probabilistic Seismic Hazard Analysis (PSHA), which requires an estimate of the future seismicity rate and its magnitude frequency distribution (MFD). This approach is effective at quantifying risk from tectonic events because the seismicity rate, once measured, is almost constant over timescales of interest. In contrast, rates of induced seismicity vary significantly over building lifetimes, largely in response to changes in injection or extraction. Thus, the key to extending PSHA to induced earthquakes is to estimate future changes of the seismicity rate in response to some proposed operating schedule. Numerical models can describe the physical link between fluid pressure, effective stress change, and the earthquake process (triggering and propagation). However, models with predictive potential of individual earthquakes face the difficulty of characterizing specific heterogeneity - stress, strength, roughness, etc. - at locations of interest. Modeling catalogs of earthquakes provides a means of averaging over this uncertainty, focusing instead on the collective features of the seismicity, e.g., its rate and MFD. The model we use incorporates fluid pressure and stress changes to describe nucleation and crack-like propagation of earthquakes on stochastically characterized 1D faults. This enables simulation of synthetic catalogs of induced seismicity from which the seismicity rate, location and MFD are extracted. A probability distribution for Mmax - the largest event in some specified time window - is also computed. Because the model captures the physics linking seismicity to changes in the reservoir, earthquake observations and operating information can be used to calibrate a

  13. Seismicity and faulting attributable to fluid extraction

    Science.gov (United States)

    Yerkes, R.F.; Castle, R.O.

    1976-01-01

    The association between fluid injection and seismicity has been well documented and widely publicized. Less well known, but probably equally widespread are faulting and shallow seismicity attributable solely to fluid extraction, particularly in association with petroleum production. Two unequivocable examples of seismicity and faulting associated with fluid extraction in the United States are: The Goose Creek, Texas oil field event of 1925 (involving surface rupture); and the Wilmington, California oil field events (involving subsurface rupture) of 1947, 1949, 1951 (2), 1955, and 1961. Six additional cases of intensity I-VII earthquakes (M pressure and attendant increase in effective stress. Surface and subsurface measurements and theoretical and model studies show that differential compaction leads not only to differential subsidence and centripetally-directed horizontal displacements, but to changes in both vertical- and horizontal-strain regimes. Study of well-documented examples indicates that the occurrence and nature of faulting and seismicity associated with compaction are functions chiefly of: (1) the pre-exploitation strain regime, and (2) the magnitude of contractional horizontal strain centered over the compacting materials relative to that of the surrounding annulus of extensional horizontal strain. The examples cited include natural systems strained only by extraction of fluids, as well as some subsequently subjected to injection. Faulting and seismicity have accompanied both decrease and subsequent increase of fluid pressures; reversal of fluid-pressure decline by injection may enhance the likelihood of subsurface faulting and seismicity due chiefly to earlier fluid pressure reduction. A consistent common denominator appears to be continuing compaction at depth; the relative effects of fluid extraction followed by injection are not easily separated. ?? 1976.

  14. Special Data Collection System (SDCS) event report, Unimak Island region, 16 May 1975

    Energy Technology Data Exchange (ETDEWEB)

    Hill, K.J.; Dawkins, M.S.; Baumstark, R.R.; Gillespie, M.D.

    1976-01-22

    Seismic data are reported from the Special Data Collection System (SDCS) and other sources for the Unimak Island Region event on 16 May 1975. Published epicenter information from seismic observations is given.

  15. Lunar seismic profiling experiment natural activity study

    Science.gov (United States)

    Duennebier, F. K.

    1976-01-01

    The Lunar Seismic Experiment Natural Activity Study has provided a unique opportunity to study the high frequency (4-20 Hz) portion to the seismic spectrum on the moon. The data obtained from the LSPE was studied to evaluate the origin and importance of the process that generates thermal moonquakes and the characteristics of the seismic scattering zone at the lunar surface. The detection of thermal moonquakes by the LSPE array made it possible to locate the sources of many events and determine that they are definitely not generated by astronaut activities but are the result of a natural process on the moon. The propagation of seismic waves in the near-surface layers was studied in a qualitative manner. In the absence of an adequate theoretical model for the propagation of seismic waves in the moon, it is not possible to assign a depth for the scattering layer. The LSPE data does define several parameters which must be satisfied by any model developed in the future.

  16. Creating Scenarios for Seismic Risk Reduction Using Geographic Information Systems

    Directory of Open Access Journals (Sweden)

    Florin Leon

    2007-01-01

    Full Text Available This paper presents a GIS-based methodology for monitoring the seismic performance, while taking into account the deteriorations revealed during GIS-based scenarios aiming at the identification of the seismic serviceability of the structure. By applying the geographical information system (GIS containing geo-spatial data, one can develop useful scenarios to improve the knowledge of structural vulnerability of the urban built infrastructure. Scenarios of modelling, simulation and non-linear seismic analysis are described and applied to a class of damaged models for some of the structures typical of the existing urban infrastructure of Jassy, Romania. The management of GIS-based seismic vulnerability of existing concrete structure is presented as a tool for awareness and mitigation of seismic effects of possible future events in the urban area.

  17. The New Madrid Seismic Zone: not dead yet.

    Science.gov (United States)

    Page, Morgan T; Hough, Susan E

    2014-02-14

    The extent to which ongoing seismicity in intraplate regions represents long-lived aftershock activity is unclear. We examined historical and instrumental seismicity in the New Madrid central U.S. region to determine whether present-day seismicity is composed predominantly of aftershocks of the 1811-1812 earthquake sequence. High aftershock productivity is required both to match the observation of multiple mainshocks and to explain the modern level of activity as aftershocks; synthetic sequences consistent with these observations substantially overpredict the number of events of magnitude ≥ 6 that were observed in the past 200 years. Our results imply that ongoing background seismicity in the New Madrid region is driven by ongoing strain accrual processes and that, despite low deformation rates, seismic activity in the zone is not decaying with time.

  18. Evaluation of seismic energy evolution

    Science.gov (United States)

    -Emilian Toader, Victorin; Marmureanu, Alexandru

    2013-04-01

    The program analyzes seismicity on a defined area with the use of bulletins (event information) provided by ANTELOPE software. These include earthquake localization (moment, latitude, longitude, magnitude, depth, P and S for each station and other parameters). The evolution of the calculated energy from the Richter magnitude is characterized by steps which can be linearly interpolated. In this way tendencies of energy accumulation / release through tectonic movement can be estimated. Also, it will be calculated and displayed the 'b' coefficient from the Gutenberg - Richter law. The results will be saved as a HTML list which allows global and individual visualization of the seismic forecasts accompanied by the epicenter position on the map. The ANTELOPE users are the first beneficiaries but the program could be modified for other formats of data which include the same information related to the earthquakes localization. The software allows to select the analysis area in which the epicenters are located. In this respect, we are using the free Google Static Maps service (in this case an internet connection is necessary) as well as there is an offline option. In a configuration file the coordinates of the epicenter area has to be defined, the zoom level and the map type if Google Maps is used. The user may redefine the investigation area in online mode. Furthermore, the program allows the selection of the time interval during which the analysis is performed, the configuration of the magnitude and depth intervals, the folders in which the ANTELOPE bulletins are located and where the results will be saved in HTML format. In a separate panel the time intervals between 2 seismic events, the resulted energy from the magnitude conversion (Ml or Md) and magnitudes - depths evolution at which the earthquakes took place can be visualized. During the analysis of the seismic bulletins generated by ANTELOPE, the epicenters are displayed dynamically in the original selected area

  19. Stress-Release Seismic Source for Seismic Velocity Measurement in Mines

    Science.gov (United States)

    Swanson, P. L.; Clark, C.; Richardson, J.; Martin, L.; Zahl, E.; Etter, A.

    2014-12-01

    Accurate seismic event locations are needed to delineate roles of mine geometry, stress and geologic structures in developing rockburst conditions. Accurate absolute locations are challenging in mine environments with rapid changes in seismic velocity due to sharp contrasts between individual layers and large time-dependent velocity gradients attending excavations. Periodic use of controlled seismic sources can help constrain the velocity in this continually evolving propagation medium comprising the miners' workplace. With a view to constructing realistic velocity models in environments in which use of explosives is problematic, a seismic source was developed subject to the following design constraints: (i) suitable for use in highly disturbed zones surrounding mine openings, (ii) able to produce usable signals over km-scale distances in the frequency range of typical coal mine seismic events (~10-100 Hz), (iii) repeatable, (iv) portable, (v) non-disruptive to mining operations, and (vi) safe for use in potentially explosive gaseous environments. Designs of the compressed load column seismic source (CLCSS), which generates a stress, or load, drop normal to the surface of mine openings, and the fiber-optic based source-initiation timer are presented. Tests were conducted in a coal mine at a depth of 500 m (1700 ft) and signals were recorded on the surface with a 72-ch (14 Hz) exploration seismograph for load drops of 150-470 kN (16-48 tons). Signal-to-noise ratios of unfiltered signals ranged from ~200 immediately above the source (500 m (1700 ft)) to ~8 at the farthest extent of the array (slant distance of ~800 m (2600 ft)), suggesting the potential for use over longer range. Results are compared with signals produced by weight drop and sledge hammer sources, indicating the superior waveform quality for first-arrival measurements with the CLCSS seismic source.

  20. Mitigating Induced Seismicity Through Active Pressure Management in Numerical Simulations

    Science.gov (United States)

    Kroll, K.; Richards-Dinger, K. B.; White, J. A.

    2016-12-01

    The recent upturn of seismicity rates in the Central and Eastern United States and Canada has been attributed to industrial operations such as waste-water disposal, hydraulic fracturing, and subsurface carbon storage. We couple the 3D, physics-based earthquake simulator, RSQSim, to a reservoir model to investigate the space-time characteristics of earthquakes induced by pore-fluid pressure increases and/or poroelastic stresses during injection. RSQSim employs rate-state friction, which gives rise to spatiotemporal earthquake clustering. The simulator generates long catalogs of seismicity based on stress changes due to fault interaction and external stress perturbations with great computational efficiency, allowing for multiple simulations to systematically explore the parameters that control induced seismicity. These simulations provide physics-based statistical data that may contribute to the formalization of optimal injection operations designed to minimize risk of seismicity at a given industrial site. Industrial operators may modify injection rates as an active seismicity mitigation tool to either reduce the total number of earthquakes or attempt to reduce the likelihood of future large events. To explore the efficacy of this approach, we use RSQSim to explore how sequences of induced earthquakes respond to changes in injection schedule. We simulate induced seismicity on a single optimally oriented fault with fractally distributed initial shear stresses and compare results from models with/without along-strike fault permeability and poroelastic stress changes. We investigate the seismic response to several injection schedules that lie between two end-member scenarios, 1) constant injection at low rates, and 2) periodic injection at high rates. We evaluate the cumulative number of events, total seismic moment release, and the spatio-temporal characteristics of seismicity including the time/location of the next large event after adjusting injection rates

  1. Induced and Natural Seismicity: Earthquake Hazards and Risks in Ohio:

    Science.gov (United States)

    Besana-Ostman, G. M.; Worstall, R.; Tomastik, T.; Simmers, R.

    2013-12-01

    To adapt with increasing need to regulate all operations related to both the Utica and Marcellus shale play within the state, ODNR had recently strengthen its regulatory capability through implementation of stricter permit requirements, additional human resources and improved infrastructure. These ODNR's efforts on seismic risk reduction related to induced seismicity led to stricter regulations and many infrastructure changes related particularly to Class II wells. Permit requirement changes and more seismic monitoring stations were implemented together with additional injection data reporting from selected Class II well operators. Considering the possible risks related to seismic events in a region with relatively low seismicity, correlation between limited seismic data and injection volume information were undertaken. Interestingly, initial results showed some indications of both plugging and fracturing episodes. The real-time data transmission from seismic stations and availability of injection volume data enabled ODNR to interact with operators and manage wells dynamically. Furthermore, initial geomorphic and structural analyses indicated possible active faults in the northern and western portion of the state oriented NE-SW. The newly-mapped structures imply possible relatively bigger earthquakes in the region and consequently higher seismic risks. With the above-mentioned recent changes, ODNR have made critical improvement of its principal regulatory role in the state for oil and gas operations but also an important contribution to the state's seismic risk reduction endeavors. Close collaboration with other government agencies and the public, and working together with the well operators enhanced ODNR's capability to build a safety culture and achieve further public and industry participation towards a safer environment. Keywords: Induced seismicity, injection wells, seismic risks

  2. BUILDING 341 Seismic Evaluation

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-15

    The Seismic Evaluation of Building 341 located at Lawrence Livermore National Laboratory in Livermore, California has been completed. The subject building consists of a main building, Increment 1, and two smaller additions; Increments 2 and 3.

  3. Seismic Creep, USA Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seismic creep is the constant or periodic movement on a fault as contrasted with the sudden rupture associated with an earthquake. It is a usually slow deformation...

  4. Optimal Retrofit Scheme for Highway Network under Seismic Hazards

    Directory of Open Access Journals (Sweden)

    Yongxi Huang

    2014-06-01

    Full Text Available Many older highway bridges in the United States (US are inadequate for seismic loads and could be severely damaged or collapsed in a relatively small earthquake. According to the most recent American Society of Civil Engineers’ infrastructure report card, one-third of the bridges in the US are rated as structurally deficient and many of these structurally deficient bridges are located in seismic zones. To improve this situation, at-risk bridges must be identified and evaluated and effective retrofitting programs should be in place to reduce their seismic vulnerabilities. In this study, a new retrofit strategy decision scheme for highway bridges under seismic hazards is developed and seamlessly integrate the scenario-based seismic analysis of bridges and the traffic network into the proposed optimization modeling framework. A full spectrum of bridge retrofit strategies is considered based on explicit structural assessment for each seismic damage state. As an empirical case study, the proposed retrofit strategy decision scheme is utilized to evaluate the bridge network in one of the active seismic zones in the US, Charleston, South Carolina. The developed modeling framework, on average, will help increase network throughput traffic capacity by 45% with a cost increase of only $15million for the Mw 5.5 event and increase the capacity fourfold with a cost of only $32m for the Mw 7.0 event.

  5. Using Safety Margins for a German Seismic PRA

    Directory of Open Access Journals (Sweden)

    Ralf Obenland

    2008-01-01

    Full Text Available The German regulatory guide demands the performance of a probabilistic risk assessment (PRA including external events. In 2005, a new methodology guideline (Methodenband based on the current state of science and technology was released to provide the analyst with a set of suitable tools and methodologies for the analysis of all PRA events. In the case of earthquake, a multilevel verification procedure is suggested. The verification procedure which has to be used depends on the seismic risk at the site of the plant. For sites in areas with low seismic activity no analysis or only a reduced analysis is proposed. This paper describes the evaluation of safety margins of buildings, structures, components and systems for plants at sites with high seismic risk, corresponding to the German methodology guideline. The seismic PRA results in an estimation of core damage frequencies caused by earthquakes. Additionally, the described approach can also be adapted for the usage in a reduced analysis for sites with lower earthquake risks. Westinghouse has wide experience in performing seismic PRA for both BWR as well as PWR plants. Westinghouse uses the documented set of seismic design analyses dating from construction phase and from later updates, if done, as a basis for a seismic PRA, which means that usually no costly new structural mechanics calculations have to be performed.

  6. Seismic margin analysis technique for nuclear power plant structures

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Jeong Moon; Choi, In Kil

    2001-04-01

    In general, the Seismic Probabilistic Risk Assessment (SPRA) and the Seismic Margin Assessment(SAM) are used for the evaluation of realistic seismic capacity of nuclear power plant structures. Seismic PRA is a systematic process to evaluate the seismic safety of nuclear power plant. In our country, SPRA has been used to perform the probabilistic safety assessment for the earthquake event. SMA is a simple and cost effective manner to quantify the seismic margin of individual structural elements. This study was performed to improve the reliability of SMA results and to confirm the assessment procedure. To achieve this goal, review for the current status of the techniques and procedures was performed. Two methodologies, CDFM (Conservative Deterministic Failure Margin) sponsored by NRC and FA (Fragility Analysis) sponsored by EPRI, were developed for the seismic margin review of NPP structures. FA method was originally developed for Seismic PRA. CDFM approach is more amenable to use by experienced design engineers including utility staff design engineers. In this study, detailed review on the procedures of CDFM and FA methodology was performed.

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

    African Journals Online (AJOL)

    The data were used to create the station history plots which display the travel times, the distance time curve and events location on a world seismicity map with Zaria as the center. KEY WORDS: History, Events, Station, Teleseismic, Travel time. Global Journal of Pure and Applied Sciences Vol.11(2) 2005: 309-315.

  8. Subsystem fragility: Seismic Safety Margins Research Program (Phase I)

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, R. P.; Campbell, R. D.; Hardy, G.; Banon, H.

    1981-10-01

    Seismic fragility levels of safety related equipment are developed for use in a seismic oriented Probabilistic Risk Assessment (PRA) being conducted as part of the Seismic Safety Margins Research Program (SSMRP). The Zion Nuclear Power Plant is being utilized as a reference plant and fragility descriptions are developed for specific and generic safety related equipment groups in Zion. Both equipment fragilities and equipment responses are defined in probabilistic terms to be used as input to the SSMRP event tree/fault tree models of the Zion systems. 65 refs., 14 figs., 11 tabs.

  9. The assessment of seismic hazard for Gori, (Georgia) and preliminary studies of seismic microzonation

    Science.gov (United States)

    Gogoladze, Z.; Moscatelli, M.; Giallini, S.; Avalle, A.; Gventsadze, A.; Kvavadze, N.; Tsereteli, N.

    2016-12-01

    Seismic risk is a crucial issue for South Caucasus, which is the main gateway between Asia and Europe. The goal of this work is to propose new methods and criteria for defining an overall approach aimed at assessing and mitigating seismic risk in Georgia. In this reguard seismic microzonation represents a highly useful tool for seismic risk assessmentin land management, for design of buildings or structures and for emergency planning.Seismic microzonation assessment of local seismic hazard,which is a component of seismicity resulting from specific local characteristics which cause local amplification and soil instability, through identification of zones with seismically homogeneous behavior. This paper presents the results of preliminary study of seismic microzonation of Gori, Georgia. Gori is and is located in the Shida Kartli region and on both sides of Liachvi and Mtkvari rivers, with area of about 135 km2around the Gori fortress. Gori is located in Achara-Trialeti fold-thrust belt, that is tectonically unstable. Half of all earthquakes in Gori area with magnitude M≥3.5 have happened along this fault zone and on basis of damage caused by previous earthquakes, this territory show the highest level of risk (the maximum value of direct losses) in central part of the town. The seismic microzonation map of level 1 for Gori was carried out using: 1) Already available data (i.e., topographic map and boreholes data), 2) Results of new geological surveys and 3) Geophysical measurements (i.e., MASW and noise measurements processed with HVSR technique). Our preliminary results highlight the presence of both stable zones susceptible to local amplifications and unstable zones susceptible to geological instability. Our results are directed to establish set of actions aimed at risk mitigation before initial onset of emergency, and to management of the emergency once the seismic event has occurred. The products obtained, will contain the basic elements of an integrated system

  10. Micro-seismicity and seismic moment release within the Coso Geothermal Field, California

    Science.gov (United States)

    Kaven, Joern; Hickman, Stephen H.; Davatzes, Nicholas C.

    2014-01-01

    We relocate 16 years of seismicity in the Coso Geothermal Field (CGF) using differential travel times and simultaneously invert for seismic velocities to improve our knowledge of the subsurface geologic and hydrologic structure. We expand on our previous results by doubling the number of relocated events from April 1996 through May 2012 using a new field-wide 3-D velocity model. Relocated micro-seismicity sharpens in many portions of the active geothermal reservoir, likely defining large-scale fault zones and fluid pressure compartment boundaries. However, a significant fraction of seismicity remains diffuse and does not cluster into sharply defined structures, suggesting that permeability is maintained within the reservoir through distributed brittle failure. The seismic velocity structure reveals heterogeneous distributions of compressional (Vp) and shear (Vs) wave speed, with Vs generally higher in the Main Field and East Flank and Vp remaining relatively uniform across the CGF, but with significant local variations. The Vp/Vs ratio appears to outline the two main producing compartments of the reservoir at depths below mean ground level of approximately 1 to 2.5 km, with a ridge of relatively high Vp/Vs separating the Main Field from the East Flank. Detailed analyses of spatial and temporal variations in earthquake relocations and cumulative seismic moment release in the East Flank reveal three regions with persistently high rates of seismic activity. Two of these regions exhibit sharp, stationary boundaries at the margins of the East Flank that likely represent barriers to fluid flow and advective heat transport. However, seismicity and moment release in a third region at the northern end of the East Flank spread over time to form an elongated NE to SW structure, roughly parallel both to an elongated cluster of seismicity at the southern end of the East Flank and to regional fault traces mapped at the surface. Our results indicate that high

  11. Community Seismic Network (CSN)

    Science.gov (United States)

    Clayton, R. W.; Heaton, T. H.; Kohler, M. D.; Cheng, M.; Guy, R.; Chandy, M.; Krause, A.; Bunn, J.; Olson, M.; Faulkner, M.; Liu, A.; Strand, L.

    2012-12-01

    We report on developments in sensor connectivity, architecture, and data fusion algorithms executed in Cloud computing systems in the Community Seismic Network (CSN), a network of low-cost sensors housed in homes and offices by volunteers in the Pasadena, CA area. The network has over 200 sensors continuously reporting anomalies in local acceleration through the Internet to a Cloud computing service (the Google App Engine) that continually fuses sensor data to rapidly detect shaking from earthquakes. The Cloud computing system consists of data centers geographically distributed across the continent and is likely to be resilient even during earthquakes and other local disasters. The region of Southern California is partitioned in a multi-grid style into sets of telescoping cells called geocells. Data streams from sensors within a geocell are fused to detect anomalous shaking across the geocell. Temporal spatial patterns across geocells are used to detect anomalies across regions. The challenge is to detect earthquakes rapidly with an extremely low false positive rate. We report on two data fusion algorithms, one that tessellates the surface so as to fuse data from a large region around Pasadena and the other, which uses a standard tessellation of equal-sized cells. Since September 2011, the network has successfully detected earthquakes of magnitude 2.5 or higher within 40 Km of Pasadena. In addition to the standard USB device, which connects to the host's computer, we have developed a stand-alone sensor that directly connects to the internet via Ethernet or wifi. This bypasses security concerns that some companies have with the USB-connected devices, and allows for 24/7 monitoring at sites that would otherwise shut down their computers after working hours. In buildings we use the sensors to model the behavior of the structures during weak events in order to understand how they will perform during strong events. Visualization models of instrumented buildings ranging

  12. Kernel Smoothing Methods for Non-Poissonian Seismic Hazard Analysis

    Science.gov (United States)

    Woo, Gordon

    2017-04-01

    For almost fifty years, the mainstay of probabilistic seismic hazard analysis has been the methodology developed by Cornell, which assumes that earthquake occurrence is a Poisson process, and that the spatial distribution of epicentres can be represented by a set of polygonal source zones, within which seismicity is uniform. Based on Vere-Jones' use of kernel smoothing methods for earthquake forecasting, these methods were adapted in 1994 by the author for application to probabilistic seismic hazard analysis. There is no need for ambiguous boundaries of polygonal source zones, nor for the hypothesis of time independence of earthquake sequences. In Europe, there are many regions where seismotectonic zones are not well delineated, and where there is a dynamic stress interaction between events, so that they cannot be described as independent. From the Amatrice earthquake of 24 August, 2016, the subsequent damaging earthquakes in Central Italy over months were not independent events. Removing foreshocks and aftershocks is not only an ill-defined task, it has a material effect on seismic hazard computation. Because of the spatial dispersion of epicentres, and the clustering of magnitudes for the largest events in a sequence, which might all be around magnitude 6, the specific event causing the highest ground motion can vary from one site location to another. Where significant active faults have been clearly identified geologically, they should be modelled as individual seismic sources. The remaining background seismicity should be modelled as non-Poissonian using statistical kernel smoothing methods. This approach was first applied for seismic hazard analysis at a UK nuclear power plant two decades ago, and should be included within logic-trees for future probabilistic seismic hazard at critical installations within Europe. In this paper, various salient European applications are given.

  13. Inflection point analysis for Greek seismicity 1900-2006

    CERN Document Server

    Christopoulos, Demetris T

    2014-01-01

    The seismicity of Greek region is studied under the prism of ESE & EDE methods for finding the inflection point of cumulative energy released. Main shocks are chosen from 106 years data. The result is that with both methods a critical time region exist at the end of 1982 to early 1983. After this time the seismicity tends to increase and gives remarkable events, like Athens Sep 1999 earthquake.

  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. Towards a Comprehensive Catalog of Volcanic Seismicity

    Science.gov (United States)

    Thompson, G.

    2014-12-01

    Catalogs of earthquakes located using differential travel-time techniques are a core product of volcano observatories, and while vital, they represent an incomplete perspective of volcanic seismicity. Many (often most) earthquakes are too small to locate accurately, and are omitted from available catalogs. Low frequency events, tremor and signals related to rockfalls, pyroclastic flows and lahars are not systematically catalogued, and yet from a hazard management perspective are exceedingly important. Because STA/LTA detection schemes break down in the presence of high amplitude tremor, swarms or dome collapses, catalogs may suggest low seismicity when seismicity peaks. We propose to develop a workflow and underlying software toolbox that can be applied to near-real-time and offline waveform data to produce comprehensive catalogs of volcanic seismicity. Existing tools to detect and locate phaseless signals will be adapted to fit within this framework. For this proof of concept the toolbox will be developed in MATLAB, extending the existing GISMO toolbox (an object-oriented MATLAB toolbox for seismic data analysis). Existing database schemas such as the CSS 3.0 will need to be extended to describe this wider range of volcano-seismic signals. WOVOdat may already incorporate many of the additional tables needed. Thus our framework may act as an interface between volcano observatories (or campaign-style research projects) and WOVOdat. We aim to take the further step of reducing volcano-seismic catalogs to sets of continuous metrics that are useful for recognizing data trends, and for feeding alarm systems and forecasting techniques. Previous experience has shown that frequency index, peak frequency, mean frequency, mean event rate, median event rate, and cumulative magnitude (or energy) are potentially useful metrics to generate for all catalogs at a 1-minute sample rate (directly comparable with RSAM and similar metrics derived from continuous data). Our framework

  16. Seismic Characterization of Coal-Mining Seismicity in Utah for CTBT Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Arabasz, W J; Pechmann, J C

    2001-03-01

    Underground coal mining (down to {approx}0.75 km depth) in the contiguous Wasatch Plateau (WP) and Book Cliffs (BC) mining districts of east-central Utah induces abundant seismicity that is monitored by the University of Utah regional seismic network. This report presents the results of a systematic characterization of mining seismicity (magnitude {le} 4.2) in the WP-BC region from January 1978 to June 2000-together with an evaluation of three seismic events (magnitude {le} 4.3) associated with underground trona mining in southwestern Wyoming during January-August 2000. (Unless specified otherwise, magnitude implies Richter local magnitude, M{sub L}.) The University of Utah Seismograph Stations (UUSS) undertook this cooperative project to assist the University of California Lawrence Livermore National Laboratory (LLNL) in research and development relating to monitoring the Comprehensive Test Ban Treaty (CTBT). The project, which formally began February 28, 1998, and ended September 1, 2000, had three basic objectives: (1) Strategically install a three-component broadband digital seismic station in the WP-BC region to ensure the continuous recording of high-quality waveform data to meet the long-term needs of LLNL, UUSS, and other interested parties, including the international CTBT community. (2) Determine source mechanisms--to the extent that available source data and resources allowed--for comparative seismic characterization of stress release in mines versus earthquakes in the WP-BC study region. (3) Gather and report to LLNL local information on mine operations and associated seismicity, including ''ground truth'' for significant events. Following guidance from LLNL's Technical Representative, the focus of Objective 2 was changed slightly to place emphasis on three mining-related events that occurred in and near the study area after the original work plan had been made, thus posing new targets of opportunity. These included: a magnitude

  17. Convergence rate controls seismicity styles in collision orogens

    Science.gov (United States)

    Dal Zilio, Luca; van Dinther, Ylona; Gerya, Taras

    2016-04-01

    The 25 April 2015 Mw 7.8 Gorkha earthquake in Nepal resulted from the unzipping of the previously locked Main Himalayan Thrust (MHT) fault, along which the Himalayan wedge is thrust over India. Strong ground shaking caused the collapse of more than half a million homes, killing more than 8500 people. Can such a large magnitude event also occur within the populated European Alps? Or is there a distinctly different seismicity pattern in different orogens? We show that their long-term seismicity patterns are indeed different and that their differences can be explained by a single parameter: their convergence rate. To do so we present the first self-consistent seismic cycle model for continental collisional margins. We use the viscoelastoplastic continuum Seismo-Thermo-Mechanical model (STM) validated for seismic cycle applications against a laboratory model (van Dinther et al., 2013a) and natural observations (van Dinther et al., 2013b), which includes Drucker-Prager plasticity and spontaneous rupture events governed by strongly rate-dependent friction. The 2-D model setup consists of two continental plates separated by an oceanic plate, in which the incipient subduction phase is followed by collisional orogeny. Results show the physically consistent spontaneous emergence of complex rupture paths, both on and off the main frontal thrust. These off-main frontal thrust events within the upper and lower plate complement the main frontal thrust seismicity leading to a Gutenberg-Richter frequency-magnitude distribution. This is a key observational feature of seismicity, which is typically not reproduced in seismic cycle models. The range of simulated b-values agrees with natural ranges, as we observe values from 0.97 up to 1.25 for convergence rates decreasing from 5 to 1 cm/yr. Decreasing convergence rates thus lead to relatively larger amounts of smaller earthquakes (increasing b-value) and lower maximum magnitudes. This change in b-value also observed to corresponds to

  18. Effects of fault heterogeneity on seismic energy and spectrum

    Science.gov (United States)

    Dragoni, Michele; Santini, Stefano

    2017-12-01

    We study the effects of friction heterogeneity on the dynamics of a seismogenic fault. To this aim, we consider a fault model containing two asperities with different static frictions and a rate-dependent dynamic friction. We consider the seismic events produced by the consecutive failure of the two asperities and study their properties as functions of the ratio between static frictions. In particular, we calculate the moment rate, the stress evolution during fault slip, the average stress drop, the partitioning of energy release, the seismic energy, the far-field waveforms and the spectrum of seismic waves. These quantities depend to various extent on the friction distribution on the fault. In particular, the stress distribution on the fault is always strongly heterogeneous at the beginning of the seismic event. Seismic energy and frictional heat decrease with increasing friction heterogeneity, while seismic efficiency is constant. We obtain an equation relating seismic efficiency to the parameters of the friction law, showing that the efficiency is maximum for smaller values of dynamic friction. The seismic spectrum depends on the friction distribution as to the positions and the values of the minima. However, under the model assumption that the slip durations are the same for both asperities, the corner frequency is independent of the friction distribution, but it depends on the friction law and on the coupling between asperities. The model provides a relation between the total radiated energy and the seismic moment that is consistent with the empirical relation between the two quantities. The fault model with one asperity is also considered as a particular case. The model is applied to the 1965 Rat Islands (Alaska) earthquake and shows the role of fault heterogeneity in controlling the spatial distribution of stress drop as well as the time dependence and the final amount of radiated energy.

  19. Comparing NDSHA and PSHA seismic hazard maps and real seismicity for the Italian territory

    Science.gov (United States)

    Peresan, Antonella; Nekrasova, Anastasia; Magrin, Andrea; Kossobokov, Vladimir; Panza, Giuliano F.

    2013-04-01

    Rigorous and objective testing of seismic hazard assessments against the real seismic activity are a necessary precondition for any responsible seismic risk assessment. Recent analysis showed that the performances of the traditional probabilistic approaches to seismic hazard assessment (PSHA) in predicting ground shaking are very unsatisfactory, particularly for large earthquakes. A viable alternative to PSHA is represented by the definition of credible scenario events by the neo-deterministic approach (NDSHA), a methodology based on the realistic modelling of seismic wave propagation, which permits the generalization of empirical observations by means of physically sound theoretical considerations. The NDSHA complements shaking data from prior earthquakes with physical modeling of ground motion from a wide set of possible earthquakes, and can be submitted to a formalized validation process and parametric tests that allows for the quantification of the uncertainties involved. Besides the standard NDSHA maps, providing estimates of maximum seismic ground motion, the flexibility of NDSHA permits to account for earthquake recurrence and eventually allows for the generation of ground shaking maps at specified return periods (i.e. probability of exceedance). This allows for a straightforward comparison between the NDSHA and the PSHA maps, which provide the hazard estimates in terms of probability of exceedance of a given threshold of ground motion at a specific site. Because seismic hazard maps seek to predict the shaking that would actually occur, the reference hazard maps for the Italian seismic code, obtained by PSHA, and the alternative ground shaking maps based on NDSHA, are cross-compared and tested against the real seismicity for the territory of Italy. The comparative analysis evidences the excessive dependency of PSHA expected ground shaking on earthquakes recurrence (i.e. on the probability threshold selected for the maps), which is affected by large

  20. Single-block rockfall dynamics inferred from seismic signal analysis

    Science.gov (United States)

    Hibert, Clément; Malet, Jean-Philippe; Bourrier, Franck; Provost, Floriane; Berger, Frédéric; Bornemann, Pierrick; Tardif, Pascal; Mermin, Eric

    2017-05-01

    Seismic monitoring of mass movements can significantly help to mitigate the associated hazards; however, the link between event dynamics and the seismic signals generated is not completely understood. To better understand these relationships, we conducted controlled releases of single blocks within a soft-rock (black marls) gully of the Rioux-Bourdoux torrent (French Alps). A total of 28 blocks, with masses ranging from 76 to 472 kg, were used for the experiment. An instrumentation combining video cameras and seismometers was deployed along the travelled path. The video cameras allow reconstructing the trajectories of the blocks and estimating their velocities at the time of the different impacts with the slope. These data are compared to the recorded seismic signals. As the distance between the falling block and the seismic sensors at the time of each impact is known, we were able to determine the associated seismic signal amplitude corrected for propagation and attenuation effects. We compared the velocity, the potential energy lost, the kinetic energy and the momentum of the block at each impact to the true amplitude and the radiated seismic energy. Our results suggest that the amplitude of the seismic signal is correlated to the momentum of the block at the impact. We also found relationships between the potential energy lost, the kinetic energy and the seismic energy radiated by the impacts. Thanks to these relationships, we were able to retrieve the mass and the velocity before impact of each block directly from the seismic signal. Despite high uncertainties, the values found are close to the true values of the masses and the velocities of the blocks. These relationships allow for gaining a better understanding of the physical processes that control the source of high-frequency seismic signals generated by rockfalls.

  1. Reservoir triggering seismicity in Greece: An evidence based review

    Science.gov (United States)

    Pavlou, Kyriaki; Drakatos, George; Kouskouna, Vasiliki; Makropoulos, Konstantinos

    2017-04-01

    First filling and water fluctuation in artificial lakes and reservoirs are known causes of local seismicity. In Greece, 117 dams were built over the past 60 years, of which, however, only 22 have a capacity greater than 20x206cm3 and could thus affect seismicity in a meaningful way. Most of these larger dams have been constructed and operated by the Greek Public Power Corporation (PPC). The paper aims at a comprehensive review of all relevant studies, undertaken so far, and critically examines the evidence of reservoir triggering seismicity and possible accelerated earthquake occurrence provided. The main reservoirs examined include the Marathon, Kremasta, Pournari, Ilarion and Polyphyto artificial lakes, all of which have recorded seismic events associated with their filling and/or operation for the time period up to 2010. Seismic activity that correlates with maximum or minimum water level fluctuations leads to conclusions about a possible triggering seismicity due to a pore pressure diffusion (drained or un-drained response). In each case we review the cross-correlation coefficients between the reservoir levels and triggered events, and discuss the reasons for their association from an engineering geological (mechanical properties of rocks and formations) and seismological (triggered events) perspective. Our work suggests that, whilst in these cases PCC performs very well the task of hydrological and energy management of the reservoirs, it is crucially important to monitor and validate the daily seismicity at and around the artificial lakes for a better understanding of the upmost limit of triggered seismicity, and possible triggered landslides in the areas surrounding its main reservoirs.

  2. Seismic Swarms at Paricutin Volcano Area. Magmatic Intrusion or Tectonic Seismicity?

    Science.gov (United States)

    Pinzon, J. I.; Nunez-Cornu, F. J.; Escudero, C. R.; Rowe, C. A.

    2014-12-01

    We relocate a seismic swarm with more than 700 earthquakes that took place between May and June 2006 in the Paricutin volcano area, Mexico inside of the Michoacan monogenetic volcanic field. This seismic swarm was recorded by the project "Mapping the Riviera Subduction Zone" (MARS), a temporary seismic network that was installed in the states of Jalisco, Colima and Michoacán between January 2006 and June 2007. Previously seismic swarms in the area were reported in the years of 1997, 1999 and 2000. For one that took place in the year of 1997 the Servicio Sismologico Nacional deployed a local network in the area, they conclude that the source of the seismicity was tectonic with depths between 18 and 12 km. The episodes of 1999 and 2000 were reported as similar to the 1997 swarm. A previous analysis of the 2006 swarm concludes that the depth of seismicity migrates from 9 to 5 km and was originated by a magmatic intrusion. We did a relocation of this swarm reading all the events and using Hypo71 and the P-wave velocity model used by the Jalisco Seismic and Acelerometric Network; a waveform analysis using cross-correlation method was also carried out. We obtained 15 earthquakes families with a correlation factor equal or greater than 0.79 and composed focal mechanism for each family. These families present a migration in depth beginning at 16 km and ended at 9 km. Our results agrees with a magmatic intrusion, but not so shallow as the previous study of the 2006 swarm.

  3. 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.

  4. Seismicity study of Javakhety highland (Southrn Georgia)

    Science.gov (United States)

    Godladze, T.; Javakhishvili, Z.; Dorbath, L.

    2011-12-01

    The Caucasus is a region of active tectonics and complex crustal structure located between the Caspian Sea to the East and the Black Sea to the west. To the North is the aseismic Eurasian shield and to the South-West and the South are the active tectonic regions of East Anatolia and the Zagros thrust and fault belt of Northwestern Iran. Main interest of our study is 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. While the region is seismically active, most of the crustal models and earthquake locations are based on field work and seismic studies of the soviet era until 2003, when recent technical advances has continued in the former USSR republics of the Southern Caucasus. Before 2003 the only broadband digital instrumentation in the region was an IRIS station in Garni, Armenia. Now there are new regional networks in Georgia, Armenia and Azerbaijan. There is considerable interest in examining the tectonics and fault structure of the region in more detail and in obtaining seismic data to develop crustal models and improve our ability to accurately locate events as the inputs for the seismic hazard assessment of the Caucasus. Several field works have been conducted in the Javakheti highland from 2009 to 2011. The goal of the intensive field investigations was multidisciplinary study of the fault structure and better understanding seismicity of the area. We relocated hypocenters of the earthquakes in the region and improved local 3D velocity model. The hypocenters derived from recently deployed local seismic network in the Javakheti highland, clearly identified seismically active structures. Fault plane solutions of analog data of the soviet time have been carefully analyzed and examined. Moment tensor inversions were performed for the recent moderate size earthquakes of the Javakheti highland associated with the fault

  5. Seismic Barrier Protection of Critical Infrastructure

    Science.gov (United States)

    Haupt, R.; Liberman, V.; Rothschild, M.

    2016-12-01

    Each year, on average a major magnitude-8 earthquake strikes somewhere in the world. In addition, 10,000 earthquake related deaths occur annually, where collapsing buildings claim by far most lives. Moreover, in recent events, industry activity of oil extraction and wastewater reinjection are suspect to cause earthquake swarms that threaten high-value oil pipeline networks, U.S. oil storage reserves, and civilian homes. Earthquake engineering building structural designs and materials have evolved over many years to minimize the destructive effects of seismic surface waves. However, even under the best engineering practices, significant damage and numbers of fatalities can still occur. In this effort, we present a concept and approach to redirect and attenuate the ground motion amplitudes of earthquake surface waves by implementing an engineered subsurface seismic barrier. The barrier is comprised of a borehole array complex that impedes and diverts destructive surface waves (typically 2-10 km wavelengths). Computational 2D and 3D seismic wave propagation models developed at MIT Lincoln Laboratory suggest that the borehole array arrangement is critical to the redirection and self-interference reduction of broadband hazardous seismic waves in the vicinity of the structure to protect. For validity, the computational models are compared with data obtained from large bench-scale physical models that contain scaled borehole arrays and trenches. Small contact shakers generate elastic waves in solid media, while contact tri-axial accelerometer arrays measure the resultant wave fields. Field tests are presently being conducted to examine the seismic power reduction across a subsurface borehole array generated by controlled, far-field seismic sources. The sources include a weight drop and oriented seismic vibrational sources that generate low frequency surface and body waves. The pre-borehole condition at the site is measured first with a tri-axial geophone arrangement. The

  6. Investigation of techniques for the development of seismic design basis using the probabilistic seismic hazard analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bernreuter, D.L.; Boissonnade, A.C.; Short, C.M.

    1998-04-01

    The Nuclear Regulatory Commission asked Lawrence Livermore National Laboratory to form a group of experts to assist them in revising the seismic and geologic siting criteria for nuclear power plants, Appendix A to 10 CFR Part 100. This document describes a deterministic approach for determining a Safe Shutdown Earthquake (SSE) Ground Motion for a nuclear power plant site. One disadvantage of this approach is the difficulty of integrating differences of opinions and differing interpretations into seismic hazard characterization. In answer to this, probabilistic seismic hazard assessment methodologies incorporate differences of opinion and interpretations among earth science experts. For this reason, probabilistic hazard methods were selected for determining SSEs for the revised regulation, 10 CFR Part 100.23. However, because these methodologies provide a composite analysis of all possible earthquakes that may occur, they do not provide the familiar link between seismic design loading requirements and engineering design practice. Therefore, approaches used to characterize seismic events (magnitude and distance) which best represent the ground motion level determined with the probabilistic hazard analysis were investigated. This report summarizes investigations conducted at 69 nuclear reactor sites in the central and eastern U.S. for determining SSEs using probabilistic analyses. Alternative techniques are presented along with justification for key choices. 16 refs., 32 figs., 60 tabs.

  7. The British Geological Survey seismic monitoring system

    Science.gov (United States)

    Ottemoller, L.; Baptie, B.; Luckett, R.

    2009-04-01

    The British Geological Survey (BGS) monitors the seismicity in and around the British Isles. The seismic network was started in the seventies and built up over the years to 146 short-period stations. An upgrade of this network started a few years ago and will result in a modern network with broadband seismometers, high dynamic range digitizers and real-time communication (Internet, ADSL, satellite). In total the network will comprise about 50 stations, with only few short-period stations remaining. Equipment is used from both Guralp and Nanometrics, and their respective software for data acquisition is used to bring the data to the centre in near real-time. The automated data processing is done through Earthworm. Event data are analysed using SEISAN. Continuous data are kept for all broadband stations and checked for quality and completeness. Real-time data is also exchanged with neighbouring networks. The data is used for routine monitoring, but also research. The main research objectives are to understand distribution of seismicity and relating earthquakes to tectonics, develop velocity and attenuation models and study the seismic hazard and earthquake effects.

  8. Controllable seismic source

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Antonio; DeRego, Paul Jeffrey; Ferrell, Patrick Andrew; Thom, Robert Anthony; Trujillo, Joshua J.; Herridge, Brian

    2015-09-29

    An apparatus for generating seismic waves includes a housing, a strike surface within the housing, and a hammer movably disposed within the housing. An actuator induces a striking motion in the hammer such that the hammer impacts the strike surface as part of the striking motion. The actuator is selectively adjustable to change characteristics of the striking motion and characteristics of seismic waves generated by the impact. The hammer may be modified to change the physical characteristics of the hammer, thereby changing characteristics of seismic waves generated by the hammer. The hammer may be disposed within a removable shock cavity, and the apparatus may include two hammers and two shock cavities positioned symmetrically about a center of the apparatus.

  9. Controllable seismic source

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Antonio; DeRego, Paul Jeffrey; Ferrel, Patrick Andrew; Thom, Robert Anthony; Trujillo, Joshua J.; Herridge, Brian

    2014-08-19

    An apparatus for generating seismic waves includes a housing, a strike surface within the housing, and a hammer movably disposed within the housing. An actuator induces a striking motion in the hammer such that the hammer impacts the strike surface as part of the striking motion. The actuator is selectively adjustable to change characteristics of the striking motion and characteristics of seismic waves generated by the impact. The hammer may be modified to change the physical characteristics of the hammer, thereby changing characteristics of seismic waves generated by the hammer. The hammer may be disposed within a removable shock cavity, and the apparatus may include two hammers and two shock cavities positioned symmetrically about a center of the apparatus.

  10. Annual 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.

    2009-12-31

    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. During FY 2009, the Hanford Seismic Network recorded nearly 3000 triggers on the seismometer system, which included over 1700 seismic events in the southeast Washington area and an additional 370 regional and teleseismic events. There were 1648 events determined to be local earthquakes relevant to the Hanford Site. Nearly all of these earthquakes were detected in the vicinity of Wooded Island, located about eight miles north of Richland just west of the Columbia River. Recording of the Wooded Island events began in January with over 250 events per month through June 2009. The frequency of events decreased starting in July 2009 to approximately 10-15 events per month through September 2009. Most of the events were considered minor (coda-length magnitude [Mc] less than 1.0) with 47 events in the 2.0-3.0 range. The estimated depths of the Wooded Island events are shallow (averaging less than 1.0 km deep) with a maximum depth estimated at 2.3 km. This places the Wooded Island events within the Columbia River Basalt Group (CRBG). The highest-magnitude event (3.0Mc

  11. A first-order seismotectonic regionalization of Mexico for seismic hazard and risk estimation

    Science.gov (United States)

    Zúñiga, F. Ramón; Suárez, Gerardo; Figueroa-Soto, Ángel; Mendoza, Avith

    2017-11-01

    The purpose of this work is to define a seismic regionalization of Mexico for seismic hazard and risk analyses. This seismic regionalization is based on seismic, geologic, and tectonic characteristics. To this end, a seismic catalog was compiled using the more reliable sources available. The catalog was made homogeneous in magnitude in order to avoid the differences in the way this parameter is reported by various agencies. Instead of using a linear regression to converts from m b and M d to M s or M w , using only events for which estimates of both magnitudes are available (i.e., paired data), we used the frequency-magnitude relations relying on the a and b values of the Gutenberg-Richter relation. The seismic regions are divided into three main categories: seismicity associated with the subduction process along the Pacific coast of Mexico, in-slab events within the down-going COC and RIV plates, and crustal seismicity associated to various geologic and tectonic regions. In total, 18 seismic regions were identified and delimited. For each, the a and b values of the Gutenberg-Richter relation were determined using a maximum likelihood estimation. The a and b parameters were repeatedly estimated as a function of time for each region, in order to confirm their reliability and stability. The recurrence times predicted by the resulting Gutenberg-Richter relations obtained are compared with the observed recurrence times of the larger events in each region of both historical and instrumental earthquakes.

  12. A first-order seismotectonic regionalization of Mexico for seismic hazard and risk estimation

    Science.gov (United States)

    Zúñiga, F. Ramón; Suárez, Gerardo; Figueroa-Soto, Ángel; Mendoza, Avith

    2017-06-01

    The purpose of this work is to define a seismic regionalization of Mexico for seismic hazard and risk analyses. This seismic regionalization is based on seismic, geologic, and tectonic characteristics. To this end, a seismic catalog was compiled using the more reliable sources available. The catalog was made homogeneous in magnitude in order to avoid the differences in the way this parameter is reported by various agencies. Instead of using a linear regression to converts from m b and M d to M s or M w , using only events for which estimates of both magnitudes are available (i.e., paired data), we used the frequency-magnitude relations relying on the a and b values of the Gutenberg-Richter relation. The seismic regions are divided into three main categories: seismicity associated with the subduction process along the Pacific coast of Mexico, in-slab events within the down-going COC and RIV plates, and crustal seismicity associated to various geologic and tectonic regions. In total, 18 seismic regions were identified and delimited. For each, the a and b values of the Gutenberg-Richter relation were determined using a maximum likelihood estimation. The a and b parameters were repeatedly estimated as a function of time for each region, in order to confirm their reliability and stability. The recurrence times predicted by the resulting Gutenberg-Richter relations obtained are compared with the observed recurrence times of the larger events in each region of both historical and instrumental earthquakes.

  13. 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 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.

  14. Fractal behaviour of the seismicity in the Southern Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    X. Lana

    2005-01-01

    Full Text Available The fractal behaviour of the seismicity in the Southern Iberian Peninsula is analysed by considering two different series of data: the distance and the elapsed time between consecutive seismic events recorded by the seismic network of the Andalusian Institute of Geophysics (AIG. The fractal analyses have been repeated by considering four threshold magnitudes of 2.5, 3.0, 3.5 and 4.0. The re-scaled analysis lets to determine if the seismicity shows strong randomness or if it is characterised by time-persistence and the cluster dimension indicates the degree of time and spatial clustering of the seismicity. Another analysis, based on the reconstruction theorem, permits to evaluate the minimum number of nonlinear equations describing the dynamical mechanism of the seismicity, its 'loss of memory', its chaotic character and the instability of a possible predicting algorithm. The results obtained depict some differences depending on distances or elapsed times and the different threshold levels of magnitude also lead to slightly different results. Additionally, only a part of the fractal tools, the re-scaled analysis, have been applied to five seismic crises in the same area.

  15. Seismicity and Improved Velocity Structure in Kuwait

    Energy Technology Data Exchange (ETDEWEB)

    Gok, R M; Rodgers, A J; Al-Enezi, A

    2006-01-26

    The Kuwait National Seismic Network (KNSN) began operation in 1997 and consists of nine three-component stations (eight short-period and one broadband) and is operated by the Kuwait Institute for Scientific Research. Although the region is largely believed to be aseismic, considerable local seismicity is recorded by KNSN. Seismic events in Kuwait are clustered in two main groups, one in the south and another in the north. The KNSN station distribution is able to capture the southern cluster within the footprint of the network but the northern cluster is poorly covered. Events tend to occur at depths ranging from the free surface to about 20 km. Events in the northern cluster tend to be deeper than those in south, however this might be an artifact of the station coverage. We analyzed KNSN recordings of nearly 200 local events to improve understanding of seismic events and crustal structure in Kuwait, performing several analyses with increasing complexity. First, we obtained an optimized one-dimensional (1D) velocity model for the entire region using the reported KNSN arrival times and routine locations. The resulting model is consistent with a recently obtained model from the joint inversion of receiver functions and surface wave group velocities. Crustal structure is capped by the thick ({approx} 7 km) sedimentary rocks of the Arabian Platform underlain by normal velocities for stable continental crust. Our new model has a crustal thickness of 44 km, constrained by an independent study of receiver functions and surface wave group velocities by Pasyanos et al (2006). Locations and depths of events after relocation with the new model are broadly consistent with those reported by KISR, although a few events move more than a few kilometers. We then used a double-difference tomography technique (tomoDD) to jointly locate the events and estimate three-dimensional (3D) velocity structure. TomoDD is based on hypoDD relocation algorithm and it makes use of both absolute and

  16. Computerized system of automated recording and processing of seismic data from the Upper Silesian microseismic network

    Energy Technology Data Exchange (ETDEWEB)

    Kornowski, J.; Sokolowski, H.

    1981-05-01

    This paper describes operation of the Upper Silesian microseismic network, developed and directed by the Central Mining Institute. Seismic events are detected by the T-8100 Racal-Thermionic multi-channel system with Willmore MK II seismic detectors, and are transmitted to the computer center, equipped with the PDP 11/45 minicomputer produced by the Digital Equipment Corp, by means of an FM system. The recording and processing system consists of the following stages: seismic event recording, determining time of seismic events, detection of shocks and elimination of disturbances, assessment of seismic energy of rocks, identifying time of shock recording, determining shock epicenter, storage of information on shocks. Basic computer codes of the system are described: shock detection, determination of time, determination of shock epicenters, statistical processing, and storage. The system collects and stores information on earthquakes and shocks caused by rock bursts. (6 refs.) (In Polish)

  17. Soil Profiles and Seismic Loading

    Directory of Open Access Journals (Sweden)

    Janotka, V.

    2006-01-01

    Full Text Available The contribution estimates different geotechnical profiles of site condition change and their influences on the computed seismic response spectra and time histories final values and forms applying on the seismic structures loading. The mentioned problems methodics attitude solution is based on the computed seismic motion parameters.

  18. Light Water Reactor Sustainability Program Advanced Seismic Soil Structure Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Bolisetti, Chandrakanth [Idaho National Lab. (INL), Idaho Falls, ID (United States); Coleman, Justin Leigh [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-06-01

    Risk calculations should focus on providing best estimate results, and associated insights, for evaluation and decision-making. Specifically, seismic probabilistic risk assessments (SPRAs) are intended to provide best estimates of the various combinations of structural and equipment failures that can lead to a seismic induced core damage event. However, in some instances the current SPRA approach has large uncertainties, and potentially masks other important events (for instance, it was not the seismic motions that caused the Fukushima core melt events, but the tsunami ingress into the facility). SPRA’s are performed by convolving the seismic hazard (this is the estimate of all likely damaging earthquakes at the site of interest) with the seismic fragility (the conditional probability of failure of a structure, system, or component given the occurrence of earthquake ground motion). In this calculation, there are three main pieces to seismic risk quantification, 1) seismic hazard and nuclear power plants (NPPs) response to the hazard, 2) fragility or capacity of structures, systems and components (SSC), and 3) systems analysis. Two areas where NLSSI effects may be important in SPRA calculations are, 1) when calculating in-structure response at the area of interest, and 2) calculation of seismic fragilities (current fragility calculations assume a lognormal distribution for probability of failure of components). Some important effects when using NLSSI in the SPRA calculation process include, 1) gapping and sliding, 2) inclined seismic waves coupled with gapping and sliding of foundations atop soil, 3) inclined seismic waves coupled with gapping and sliding of deeply embedded structures, 4) soil dilatancy, 5) soil liquefaction, 6) surface waves, 7) buoyancy, 8) concrete cracking and 9) seismic isolation The focus of the research task presented here-in is on implementation of NLSSI into the SPRA calculation process when calculating in-structure response at the area

  19. NSR&D Program Fiscal Year (FY) 2015 Call for Proposals Mitigation of Seismic Risk at Nuclear Facilities using Seismic Isolation

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Justin [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-02-01

    Seismic isolation (SI) has the potential to drastically reduce seismic response of structures, systems, or components (SSCs) and therefore the risk associated with large seismic events (large seismic event could be defined as the design basis earthquake (DBE) and/or the beyond design basis earthquake (BDBE) depending on the site location). This would correspond to a potential increase in nuclear safety by minimizing the structural response and thus minimizing the risk of material release during large seismic events that have uncertainty associated with their magnitude and frequency. The national consensus standard America Society of Civil Engineers (ASCE) Standard 4, Seismic Analysis of Safety Related Nuclear Structures recently incorporated language and commentary for seismically isolating a large light water reactor or similar large nuclear structure. Some potential benefits of SI are: 1) substantially decoupling the SSC from the earthquake hazard thus decreasing risk of material release during large earthquakes, 2) cost savings for the facility and/or equipment, and 3) applicability to both nuclear (current and next generation) and high hazard non-nuclear facilities. Issue: To date no one has evaluated how the benefit of seismic risk reduction reduces cost to construct a nuclear facility. Objective: Use seismic probabilistic risk assessment (SPRA) to evaluate the reduction in seismic risk and estimate potential cost savings of seismic isolation of a generic nuclear facility. This project would leverage ongoing Idaho National Laboratory (INL) activities that are developing advanced (SPRA) methods using Nonlinear Soil-Structure Interaction (NLSSI) analysis. Technical Approach: The proposed study is intended to obtain an estimate on the reduction in seismic risk and construction cost that might be achieved by seismically isolating a nuclear facility. The nuclear facility is a representative pressurized water reactor building nuclear power plant (NPP) structure

  20. Micro-seismicity in the Gulf of Cadiz: Is there a link between micro-seismicity, high magnitude earthquakes and active faults?

    Science.gov (United States)

    Silva, Sónia; Terrinha, Pedro; Matias, Luis; Duarte, João C.; Roque, Cristina; Ranero, César R.; Geissler, Wolfram H.; Zitellini, Nevio

    2017-10-01

    The Gulf of Cadiz seismicity is characterized by persistent low to intermediate magnitude earthquakes, occasionally punctuated by high magnitude events such as the M 8.7 1755 Great Lisbon earthquake and the M = 7.9 event of February 28th, 1969. Micro-seismicity was recorded during 11 months by a temporary network of 25 ocean bottom seismometers (OBSs) in an area of high seismic activity, encompassing the potential source areas of the mentioned large magnitude earthquakes. We combined micro-seismicity analysis with processing and interpretation of deep crustal seismic reflection profiles and available refraction data to investigate the possible tectonic control of the seismicity in the Gulf of Cadiz area. Three controlling mechanisms are explored: i) active tectonic structures, ii) transitions between different lithospheric domains and inherited Mesozoic structures, and iii) fault weakening mechanisms. Our results show that micro-seismicity is mostly located in the upper mantle and is associated with tectonic inversion of extensional rift structures and to the transition between different lithospheric/rheological domains. Even though the crustal structure is well imaged in the seismic profiles and in the bathymetry, crustal faults show low to negligible seismic activity. A possible explanation for this is that the crustal thrusts are thin-skinned structures rooting in relatively shallow sub-horizontal décollements associated with (aseismic) serpentinization levels at the top of the lithospheric mantle. Therefore, co-seismic slip along crustal thrusts may only occur during large magnitude events, while for most of the inter-seismic cycle these thrusts remain locked, or slip aseismically. We further speculate that high magnitude earthquake's ruptures may only nucleate in the lithospheric mantle and then propagate into the crust across the serpentinized layers.

  1. Design response spectra-compliant real and synthetic GMS for seismic analysis of seismically isolated nuclear reactor containment building

    Directory of Open Access Journals (Sweden)

    Ahmer Ali

    2017-06-01

    Full Text Available Due to the severe impacts of recent earthquakes, the use of seismic isolation is paramount for the safety of nuclear structures. The diversity observed in seismic events demands ongoing research to analyze the devastating attributes involved, and hence to enhance the sustainability of base-isolated nuclear power plants. This study reports the seismic performance of a seismically-isolated nuclear reactor containment building (NRCB under strong short-period ground motions (SPGMs and long-period ground motions (LPGMs. The United States Nuclear Regulatory Commission-based design response spectrum for the seismic design of nuclear power plants is stipulated as the reference spectrum for ground motion selection. Within the period range(s of interest, the spectral matching of selected records with the target spectrum is ensured using the spectral-compatibility approach. NRC-compliant SPGMs and LPGMs from the mega-thrust Tohoku earthquake are used to obtain the structural response of the base-isolated NRCB. To account for the lack of earthquakes in low-to-moderate seismicity zones and the gap in the artificial synthesis of long-period records, wavelet-decomposition based autoregressive moving average modeling for artificial generation of real ground motions is performed. Based on analysis results from real and simulated SPGMs versus LPGMs, the performance of NRCBs is discussed with suggestions for future research and seismic provisions.

  2. Design response spectra-compliant real and synthetic GMS for seismic analysis of seismically isolated nuclear reactor containment building

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Ahmer [ENVICO Consultants Co. Ltd., Seoul (Korea, Republic of); Abu-Hayah, Nadin; Kim, Doo Kie [Civil and Environmental Engineering, Kunsan National University, Gunsan (Korea, Republic of); Cho, Sung Gook [Innose Tech Co., Ltd., Incheon (Korea, Republic of)

    2017-06-15

    Due to the severe impacts of recent earthquakes, the use of seismic isolation is paramount for the safety of nuclear structures. The diversity observed in seismic events demands ongoing research to analyze the devastating attributes involved, and hence to enhance the sustainability of base-isolated nuclear power plants. This study reports the seismic performance of a seismically-isolated nuclear reactor containment building (NRCB) under strong short-period ground motions (SPGMs) and long-period ground motions (LPGMs). The United States Nuclear Regulatory Commission-based design response spectrum for the seismic design of nuclear power plants is stipulated as the reference spectrum for ground motion selection. Within the period range(s) of interest, the spectral matching of selected records with the target spectrum is ensured using the spectral-compatibility approach. NRC-compliant SPGMs and LPGMs from the mega-thrust Tohoku earthquake are used to obtain the structural response of the base-isolated NRCB. To account for the lack of earthquakes in low-to-moderate seismicity zones and the gap in the artificial synthesis of long-period records, wavelet-decomposition based autoregressive moving average modeling for artificial generation of real ground motions is performed. Based on analysis results from real and simulated SPGMs versus LPGMs, the performance of NRCBs is discussed with suggestions for future research and seismic provisions.

  3. Comparative analysis of seismic risk assessment methodology

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chang Kyoo; Kim, Tae Woon; Hwang, Mi Jung [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1994-07-01

    SRA methodologies are separated into SPSA and SMM. SPSA methodology that has been widely used for seismic risk analysis has two kinds of methodologies such as Zion method and SSMRP method. SPSA methodology is suitable to interfacing with the analysis of internal event. However, the results of SPSA have uncertainties because of uncertainties in seismic hazard analysis and subjective judgement. Zion method specially developed for commercial use is less expensive and less time consuming but more uncertain than SSMRP method, since the former performs the fragility analysis less in detail than the latter. SMM is impossible to interface with the analysis of internal event but the uncertainties that are occurred during seismic hazard analysis is reduced because of the screening using RLE (review level earthquake). Therefore, if SPSA-based SMM methodology is chosen to be developed, the results of SRA will be more reliable and it requires low costs and time. In addition, the new methodology will require the development of a new evaluating code for SRA. (Author) 26 refs., 25 figs., 16 tabs.

  4. Pre-seismic, co-seismic and post-seismic displacements associated ...

    Indian Academy of Sciences (India)

    Pre-seismic, co-seismic and post-seismic displacements associated with the Bhuj 2001 earthquake derived from recent and historic geodetic data. Sridevi Jade M Mukul I A Parvez M B Ananda P D Kumar V K Gaur R Bendick R Bilham F Blume K Wallace I A Abbasi M Asif Khan S Ulhadi. Volume 112 Issue 3 September ...

  5. Mobile seismic exploration

    Energy Technology Data Exchange (ETDEWEB)

    Dräbenstedt, A., E-mail: a.draebenstedt@polytec.de, E-mail: rembe@iei.tu-clausthal.de, E-mail: ulrich.polom@liag-hannover.de; Seyfried, V. [Research & Development, Polytec GmbH, Waldbronn (Germany); Cao, X.; Rembe, C., E-mail: a.draebenstedt@polytec.de, E-mail: rembe@iei.tu-clausthal.de, E-mail: ulrich.polom@liag-hannover.de [Institute of Electrical Information Technology, TU Clausthal, Clausthal-Zellerfeld (Germany); Polom, U., E-mail: a.draebenstedt@polytec.de, E-mail: rembe@iei.tu-clausthal.de, E-mail: ulrich.polom@liag-hannover.de [Leibniz Institute of Applied Geophysics, Hannover (Germany); Pätzold, F.; Hecker, P. [Institute of Flight Guidance, TU Braunschweig, Braunschweig (Germany); Zeller, T. [Clausthaler Umwelttechnik Institut CUTEC, Clausthal-Zellerfeld (Germany)

    2016-06-28

    Laser-Doppler-Vibrometry (LDV) is an established technique to measure vibrations in technical systems with picometer vibration-amplitude resolution. Especially good sensitivity and resolution can be achieved at an infrared wavelength of 1550 nm. High-resolution vibration measurements are possible over more than 100 m distance. This advancement of the LDV technique enables new applications. The detection of seismic waves is an application which has not been investigated so far because seismic waves outside laboratory scales are usually analyzed at low frequencies between approximately 1 Hz and 250 Hz and require velocity resolutions in the range below 1 nm/s/√Hz. Thermal displacements and air turbulence have critical influences to LDV measurements at this low-frequency range leading to noise levels of several 100 nm/√Hz. Commonly seismic waves are measured with highly sensitive inertial sensors (geophones or Micro Electro-Mechanical Sensors (MEMS)). Approaching a laser geophone based on LDV technique is the topic of this paper. We have assembled an actively vibration-isolated optical table in a minivan which provides a hole in its underbody. The laser-beam of an infrared LDV assembled on the optical table impinges the ground below the car through the hole. A reference geophone has detected remaining vibrations on the table. We present the results from the first successful experimental demonstration of contactless detection of seismic waves from a movable vehicle with a LDV as laser geophone.

  6. Understanding induced seismicity

    NARCIS (Netherlands)

    Elsworth, Derek; Spiers, Christopher J.|info:eu-repo/dai/nl/304829323; Niemeijer, Andre R.|info:eu-repo/dai/nl/370832132

    2016-01-01

    Fluid injection–induced seismicity has become increasingly widespread in oil- and gas-producing areas of the United States (1–3) and western Canada. It has shelved deep geothermal energy projects in Switzerland and the United States (4), and its effects are especially acute in Oklahoma, where

  7. 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

  8. Induced seismicity associated with enhanced geothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Majer, Ernest; Majer, Ernest L.; Baria, Roy; Stark, Mitch; Oates, Stephen; Bommer, Julian; Smith, Bill; Asanuma, Hiroshi

    2006-09-26

    Enhanced Geothermal Systems (EGS) offer the potential to significantly add to the world energy inventory. As with any development of new technology, some aspects of the technology has been accepted by the general public, but some have not yet been accepted and await further clarification before such acceptance is possible. One of the issues associated with EGS is the role of microseismicity during the creation of the underground reservoir and the subsequent extraction of the energy. The primary objectives of this white paper are to present an up-to-date review of the state of knowledge about induced seismicity during the creation and operation of enhanced geothermal systems, and to point out the gaps in knowledge that if addressed will allow an improved understanding of the mechanisms generating the events as well as serve as a basis to develop successful protocols for monitoring and addressing community issues associated with such induced seismicity. The information was collected though literature searches as well as convening three workshops to gather information from a wide audience. Although microseismicity has been associated with the development of production and injection operations in a variety of geothermal regions, there have been no or few adverse physical effects on the operations or on surrounding communities. Still, there is public concern over the possible amount and magnitude of the seismicity associated with current and future EGS operations. It is pointed out that microseismicity has been successfully dealt with in a variety of non-geothermal as well as geothermal environments. Several case histories are also presented to illustrate a variety of technical and public acceptance issues. It is concluded that EGS Induced seismicity need not pose any threat to the development of geothermal resources if community issues are properly handled. In fact, induced seismicity provides benefits because it can be used as a monitoring tool to understand the

  9. Seismic Fracture Characterization Methodologies for Enhanced Geothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Queen, John H. [Hi-Geophysical, Inc., Ponca, OK (United States)

    2016-05-09

    effective seismic tools for getting information on the internal structure of faults and fractures in support of fluid flow pathway management and EGS treatment. Scattered events similar to those expected from faults and fractures are seen in the VSP reported here. Unfortunately, the source offset and well depth coverage do not allow for detailed analysis of these events. This limited coverage also precluded the use of advanced migration and imaging algorithms. More extensive acquisition is needed to support fault and fracture characterization in the geothermal reservoir at Brady's Hot Springs. The VSP was effective in generating interval velocity estimates over the depths covered by the array. Upgoing reflection events are also visible in the VSP results at locations corresponding to reflection events in the surface seismic. Overall, the high temperature rated fiber optic sensors used in the VSP produced useful results. Modeling has been found useful in the interpretation of both surface reflection seismic and VSP data. It has helped identify possible near surface scattering in the surface seismic data. It has highlighted potential scattering events from deeper faults in the VSP data. Inclusion of more detailed fault and fracture specific stiffness parameters are needed to fully interpret fault and fracture scattered events for flow properties (Pyrak-Nolte and Morris, 2000, Zhu and Snieder, 2002). Shear wave methods were applied in both the surface seismic reflection and VSP work. They were not found to be effective in the Brady's Hot Springs area. This was due to the extreme attenuation of shear waves in the near surface at Brady's. This does not imply that they will be ineffective in general. In geothermal areas where good shear waves can be recorded, modeling suggests they should be very useful for characterizing faults and fractures.

  10. 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.

  11. The Algerian Seismic Network: Performance from data quality analysis

    Science.gov (United States)

    Yelles, Abdelkarim; Allili, Toufik; Alili, Azouaou

    2013-04-01

    Seismic monitoring in Algeria has seen a great change after the Boumerdes earthquake of May 21st, 2003. Indeed the installation of a New Digital seismic network (ADSN) upgrade drastically the previous analog telemetry network. During the last four years, the number of stations in operation has greatly increased to 66 stations with 15 Broad Band, 02 Very Broad band, 47 Short period and 21 accelerometers connected in real time using various mode of transmission ( VSAT, ADSL, GSM, ...) and managed by Antelope software. The spatial distribution of these stations covers most of northern Algeria from east to west. Since the operation of the network, significant number of local, regional and tele-seismic events was located by the automatic processing, revised and archived in databases. This new set of data is characterized by the accuracy of the automatic location of local seismicity and the ability to determine its focal mechanisms. Periodically, data recorded including earthquakes, calibration pulse and cultural noise are checked using PSD (Power Spectral Density) analysis to determine the noise level. ADSN Broadband stations data quality is controlled in quasi real time using the "PQLX" software by computing PDFs and PSDs of the recordings. Some other tools and programs allow the monitoring and the maintenance of the entire electronic system for example to check the power state of the system, the mass position of the sensors and the environment conditions (Temperature, Humidity, Air Pressure) inside the vaults. The new design of the network allows management of many aspects of real time seismology: seismic monitoring, rapid determination of earthquake, message alert, moment tensor estimation, seismic source determination, shakemaps calculation, etc. The international standards permit to contribute in regional seismic monitoring and the Mediterranean warning system. The next two years with the acquisition of new seismic equipment to reach 50 new BB stations led to

  12. Relationships Between Seismicity and GPS Determined Velocities in Northeast Asia

    Science.gov (United States)

    Fujita, K.; Sella, G.; Mackey, K. G.; Stein, S.; Park, K.; Imaev, V. S.

    2004-12-01

    Published GPS data are equivocal about the existence of the Okhotsk and Amur plates in northeast Asia. Seismicity data, however, clearly delineate these plates, as well as possible additional blocks. The northern boundary of the Okhotsk plate is separated from both North America and Eurasia by diffuse zones of seismicity in northeast Russia. Seismicity in the Magadan region coincides with faults clearly visible in satellite imagery that are left-lateral based on offset rivers and focal mechanisms. The largest earthquakes (~M 5) are associated with specific faults. Although GPS velocities are generally consistent with the motion of North America, their residual velocity (with respect to North America) shows a gradient across this zone of seismicity with relative displacements increasing towards the Okhotsk plate. The eastern boundary of the Amur plate is generally accepted as lying along Sakhalin Island and bordering the Okhotsk plate. However, several bands of north-south seismicity exist west of this boundary along possible extensions of the Tanlu fault of northeastern China. This seismicity extends the Tanlu to intersect with an east-west striking zone of seismicity separating Amur and Eurasia which connects Lake Baikal and Sakhalin. This seismic extension of the Tanlu implies that a small block may exist between Okhotsk and Amur that extends south to include Korea. Although the events are small, the linear and arcuate trends in seismicity clearly imply active motion along specific faults. However, there is no clear signature of active faulting in the geomorphology or geology. GPS sites in eastern Amur are too close to active to constrain block motions, however, additional blocks may be needed in interpreting GPS results from Amur, Sakhalin, Korea, and northeast China, especially given the low velocities with respect to Eurasia.

  13. Diffraction Seismic Imaging of the Chalk Group Reservoir Rocks

    Science.gov (United States)

    Montazeri, M.; Fomel, S.; Nielsen, L.

    2016-12-01

    In this study we investigate seismic diffracted waves instead of seismic reflected waves, which are usually much stronger and carry most of the information regarding subsurface structures. The goal of this study is to improve imaging of small subsurface features such as faults and fractures. Moreover, we focus on the Chalk Group, which contains important groundwater resources onshore and oil and gas reservoirs in the Danish sector of the North Sea. Finding optimum seismic velocity models for the Chalk Group and estimating high-quality stacked sections with conventional processing methods are challenging tasks. Here, we try to filter out as much as possible of undesired arrivals before stacking the seismic data. Further, a plane-wave destruction method is applied on the seismic stack in order to dampen the reflection events and thereby enhance the visibility of the diffraction events. After this initial processing, we estimate the optimum migration velocity using diffraction events in order to obtain a better resolution stack. The results from this study demonstrate how diffraction imaging can be used as an additional tool for improving the images of small-scale features in the Chalk Group reservoir, in particular faults and fractures. Moreover, we discuss the potential of applying this approach in future studies focused on such reservoirs.

  14. High Voltage Seismic Generator

    Science.gov (United States)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes

  15. Third Quarter Hanford Seismic Report for Fiscal Year 2010

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-29

    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. The Hanford Seismic Network recorded 23 local earthquakes during the third quarter of FY 2010. Sixteen earthquakes were located at shallow depths (less than 4 km), five earthquakes at intermediate depths (between 4 and 9 km), most likely in the pre-basalt sediments, and two earthquakes were located at depths greater than 9 km, within the basement. Geographically, twelve earthquakes were located in known swarm areas, 3 earthquakes occurred near a geologic structure (Saddle Mountain anticline), and eight earthquakes were classified as random events. The highest magnitude event (3.0 Mc) was recorded on May 8, 2010 at depth 3.0 km with epicenter located near the Saddle Mountain anticline. Later in the quarter (May 24 and June 28) two additional earthquakes were also recorded nearly at the same location. These events are not considered unusual in that earthquakes have been previously recorded at this location, for example, in October 2006 (Rohay et al; 2007). Six earthquakes were detected in the vicinity of Wooded Island, located about eight miles north of Richland just

  16. The performance of the stations of the Romanian seismic network in monitoring the local seismic activity

    Science.gov (United States)

    Ardeleanu, Luminita Angela; Neagoe, Cristian

    2014-05-01

    The seismic survey of the territory of Romania is mainly performed by the national seismic network operated by the National Institute for Earth Physics of Bucharest. After successive developments and upgrades, the network consists at present of 123 permanent stations equipped with high quality digital instruments (Kinemetrics K2, Quantera Q330, Quantera Q330HR, PS6-24 and Basalt digitizers) - 102 real time and 20 off-line stations - which cover the whole territory of the country. All permanent stations are supplied with 3 component accelerometers (episenzor type), while the real time stations are in addition provided with broadband (CMG3ESP, CMG40T, KS2000, KS54000, KS2000, CMG3T, STS2) or short period (SH-1, S13, Mark l4c, Ranger, GS21, L22_VEL) velocity sensors. Several communication systems are currently used for the real time data transmission: an analog line in UHF band, a line through GPRS (General Packet Radio Service), a dedicated line through satellite, and a dedicated line provided by the Romanian Special Telecommunication Service. During the period January 1, 2006 - June 30, 2013, 5936 shallow depth seismic events - earthquakes and quarry blasts - with local magnitude ML ≥ 1.2 were localized on the Romanian territory, or in its immediate vicinity, using the records of the national seismic network; 1467 subcrustal earthquakes (depth ≥ 60 km) with magnitude ML ≥ 1.9 were also localized in the Vrancea region, at the bend of the Eastern Carpathians. The goal of the present study is to evaluate the individual contribution of the real time seismic stations to the monitoring of the local seismicity. The performance of each station is estimated by taking into consideration the fraction of events that are localised using the station records, compared to the total number of events of the catalogue, occurred during the time of station operation. Taking into account the nonuniform space distribution of earthquakes, the location of the site and the recovery

  17. Seismic history of the Maltese islands and considerations on seismic risk

    Directory of Open Access Journals (Sweden)

    P. Galea

    2007-06-01

    Full Text Available A historical catalogue of felt earthquakes in the Maltese islands has been compiled dating back to 1530. Although no fatalities were officially recorded during this time as a direct consequence of earthquake effects, serious damage to buildings occurred several times. In the catalogue time period, the islands experienced EMS-98 intensity VII-VIII once (11 January 1693 and intensity VII, or VI-VII five times. The northern segment of the Hyblean-Malta plateau is the source region which appears to pose the greatest threat, although large Greek events and lower magnitude Sicily Channel events also produced damage. Estimates of return periods for intensity ?V are presented, and it is shown that expected peak ground accelerations justify the implementation of, at least, minimum anti-seismic provisions. The rapid and continual increase in the local building stock on the densely-populated islands warrants the implementation of an appropriate seismic building code to be enforced.

  18. Induced Seismicity in Oklahoma Affects Shallow Groundwater

    Science.gov (United States)

    Wang, C. Y.; Manga, M.; Shirzaei, M.; Weingarten, M.

    2016-12-01

    Natural earthquakes are known to cause a wide spectrum of hydrologic responses. Here we show that these responses also occurred following some of the recent M>5 earthquakes likely induced by wastewater injection in Oklahoma. Following the 3 September 2016 Mw 5.8 earthquake near Pawnee, for example, increased discharge in a stream near the epicentre and some injection wells was documented by a USGS stream gauge. Sand blows and ground cracks that may reflect subsurface liquefaction and lateral spreading were also observed near Pawnee. As another example, following the 13 February 2016 Mw 5.1 earthquake near Fairview, changes of groundwater level were documented in several wells of the Oklahoma Water Resources Board. Some of the observed changes are consistent with increased permeability produced by seismic waves. Fluid injection may thus influence the hydrogeological properties of shallow groundwater systems and aquifers by inducing seismicity, if the induced events are large enough.

  19. DEFORMATION WAVES AS A TRIGGER MECHANISM OF SEISMIC ACTIVITY IN SEISMIC ZONES OF THE CONTINENTAL LITHOSPHERE

    Directory of Open Access Journals (Sweden)

    S. I. Sherman

    2013-01-01

    Full Text Available Deformation waves as a trigger mechanism of seismic activity and migration of earthquake foci have been under discussion by researchers in seismology and geodynamics for over 50 years. Four sections of this article present available principal data on impacts of wave processes on seismicity and new data. The first section reviews analytical and experimental studies aimed at identification of relationships between wave processes in the lithosphere and seismic activity manifested as space-and-time migration of individual earthquake foci or clusters of earthquakes. It is concluded that with a systematic approach, instead of using a variety of terms to denote waves that trigger seismic process in the lithosphere, it is reasonable to apply the concise definition of ‘deformation waves’, which is most often used in fact.The second section contains a description of deformation waves considered as the trigger mechanism of seismic activity. It is concluded that a variety of methods are applied to identify deformation waves, and such methods are based on various research methods and concepts that naturally differ in sensitivity concerning detection of waves and/or impact of the waves on seismic process. Epicenters of strong earthquakes are grouped into specific linear or arc-shaped systems, which common criterion is the same time interval of the occurrence of events under analysis. On site the systems compose zones with similar time sequences, which correspond to the physical notion of moving waves (Fig. 9. Periods of manifestation of such waves are estimated as millions of years, and a direct consideration of the presence of waves and wave parameters is highly challenging. In the current state-of-the-art, geodynamics and seismology cannot provide any other solution yet.The third section presents a solution considering record of deformation waves in the lithosphere. With account of the fact that all the earthquakes with М≥3.0 are associated with

  20. DEFORMATION WAVES AS A TRIGGER MECHANISM OF SEISMIC ACTIVITY IN SEISMIC ZONES OF THE CONTINENTAL LITHOSPHERE

    Directory of Open Access Journals (Sweden)

    S. I. Sherman

    2015-09-01

    Full Text Available Deformation waves as a trigger mechanism of seismic activity and migration of earthquake foci have been under discussion by researchers in seismology and geodynamics for over 50 years. Four sections of this article present available principal data on impacts of wave processes on seismicity and new data. The first section reviews analytical and experimental studies aimed at identification of relationships between wave processes in the lithosphere and seismic activity manifested as space-and-time migration of individual earthquake foci or clusters of earthquakes. It is concluded that with a systematic approach, instead of using a variety of terms to denote waves that trigger seismic process in the lithosphere, it is reasonable to apply the concise definition of ‘deformation waves’, which is most often used in fact.The second section contains a description of deformation waves considered as the trigger mechanism of seismic activity. It is concluded that a variety of methods are applied to identify deformation waves, and such methods are based on various research methods and concepts that naturally differ in sensitivity concerning detection of waves and/or impact of the waves on seismic process. Epicenters of strong earthquakes are grouped into specific linear or arc-shaped systems, which common criterion is the same time interval of the occurrence of events under analysis. On site the systems compose zones with similar time sequences, which correspond to the physical notion of moving waves (Fig. 9. Periods of manifestation of such waves are estimated as millions of years, and a direct consideration of the presence of waves and wave parameters is highly challenging. In the current state-of-the-art, geodynamics and seismology cannot provide any other solution yet.The third section presents a solution considering record of deformation waves in the lithosphere. With account of the fact that all the earthquakes with М≥3.0 are associated with

  1. The California Integrated Seismic Network

    Science.gov (United States)

    Hellweg, M.; Given, D.; Hauksson, E.; Neuhauser, D.; Oppenheimer, D.; Shakal, A.

    2007-05-01

    The mission of the California Integrated Seismic Network (CISN) is to operate a reliable, modern system to monitor earthquakes throughout the state; to generate and distribute information in real-time for emergency response, for the benefit of public safety, and for loss mitigation; and to collect and archive data for seismological and earthquake engineering research. To meet these needs, the CISN operates data processing and archiving centers, as well as more than 3000 seismic stations. Furthermore, the CISN is actively developing and enhancing its infrastructure, including its automated processing and archival systems. The CISN integrates seismic and strong motion networks operated by the University of California Berkeley (UCB), the California Institute of Technology (Caltech), and the United States Geological Survey (USGS) offices in Menlo Park and Pasadena, as well as the USGS National Strong Motion Program (NSMP), and the California Geological Survey (CGS). The CISN operates two earthquake management centers (the NCEMC and SCEMC) where statewide, real-time earthquake monitoring takes place, and an engineering data center (EDC) for processing strong motion data and making it available in near real-time to the engineering community. These centers employ redundant hardware to minimize disruptions to the earthquake detection and processing systems. At the same time, dual feeds of data from a subset of broadband and strong motion stations are telemetered in real- time directly to both the NCEMC and the SCEMC to ensure the availability of statewide data in the event of a catastrophic failure at one of these two centers. The CISN uses a backbone T1 ring (with automatic backup over the internet) to interconnect the centers and the California Office of Emergency Services. The T1 ring enables real-time exchange of selected waveforms, derived ground motion data, phase arrivals, earthquake parameters, and ShakeMaps. With the goal of operating similar and redundant

  2. Seismic history of the Altai-Sayan region and the 2011-2012 earthquakes in Tuva

    OpenAIRE

    Aleksandr N. Ovsyuchenko; Yuri V. Butanaev

    2017-01-01

    The Tuva earthquakes of 2011-2012, being the strongest in the history of seismic study in Tuva, attracted the attention of professionals and became the first well-studied seismic events in Tuva. The paper provides a general overview of seismic history of the Altai-Sayan region and a look at a particular seismogenic structure – the Kaakhem system of active faults), where the 2011-2012 earthquakes occurred. A reconstruction of the seismic history of Tuva can follow a number of paths – a...

  3. Correlation between seismicity and barometric tidal exalting

    Directory of Open Access Journals (Sweden)

    D. N. Arabelos

    2008-10-01

    Full Text Available Changes of barometric pressure in the area of Thessaloniki in Northern Greece were studied by analyzing a sample of 31 years of hourly measurements. The results of this analysis on the periodicities of tidal components are expressed in terms of amplitude and phases variability. An earlier investigation revealed a detectable correlation between the exalting of the amplitude parameters of the tidal waves with strong seismic events. A problem of this work was that we had compared the tidal parameters resulting from the analysis of data covering the period of one year with instantaneous seismic events, although the earthquake is the final result of a tectonic process of the upper lithosphere. Consequently, in order to increase the resolution of our method we had analyzed our data in groups of 3-months extent and the resulted amplitudes were compared with seismicity index for corresponding time periods. A stronger correlation was found in the last case. However, the estimation of tidal parameters in this case was restricted to short period (from one day down to eight hours constituents. Therefore, a new analysis was performed, retaining the one-year length of each data block but shifting the one year window by steps of three months from the beginning to the end of the 31 years period. This way, we are able to estimate again tidal parameters ranging from periods of one year (Sa down to eight hours (M3. The resulting correlation between these tidal parameters with a cumulative seismicity index for corresponding time intervals was remarkably increased.

  4. Probabilistic Seismic Hazard Disaggregation Analysis for the South of Portugal

    Science.gov (United States)

    Rodrigues, I.; Sousa, M.; Teves-Costa, P.

    2010-12-01

    Probabilistic seismic hazard disaggregation analysis was performed and seismic scenarios were identified for Southern Mainland Portugal. This region’s seismicity is characterized by small and moderate magnitude events and by the sporadic occurrence of large earthquakes (e.g. the 1755 Lisbon earthquake). Thus, the Portuguese Civil Protection Agency (ANPC) sponsored a collaborative research project for the study of the seismic and tsunami risks in the Algarve (project ERSTA). In the framework of this project, a series of new developments were obtained, namely the revision of the seismic catalogue (IM, 2008), the delineation of new seismogenic zones affecting the Algarve region, which reflects the growing knowledge of this region's seismotectonic context, the derivation of new spectral attenuation laws (Carvalho and Campos Costa, 2008) and the revision of the probabilistic seismic hazard (Sousa et al. 2008). Seismic hazard was disaggregated considering different spaces of random variables, namely, bivariate conditional hazard distributions of X-Y (seismic source latitude and longitude) and multivariate 4D conditional hazard distributions of M-(X-Y)-ɛ (ɛ - deviation of ground motion to the median value predicted by an attenuation model). These procedures were performed for the peak ground acceleration (PGA) and for the 5% damped 1.0 and 2.5 Hz spectral acceleration levels of three return periods: 95, 475 and 975 years. The seismic scenarios controlling the hazard of a given ground motion level, were identified as the modal values of the 4D disaggregation analysis for each of the 84 parishes of the Algarve region. Those scenarios, based on a probabilistic analysis, are meant to be used in the emergency planning as a complement to the historical scenarios that severely affected this region. Seismic scenarios share a few number of geographical locations for all return periods. Moreover, seismic hazard of most Algarve’s parishes is dominated by the seismicity located

  5. Annual Hanford Seismic Report for Fiscal Year 2010

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-12-27

    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. During FY 2010, the Hanford Seismic Network recorded 873 triggers on the seismometer system, which included 259 seismic events in the southeast Washington area and an additional 324 regional and teleseismic events. There were 210 events determined to be local earthquakes relevant to the Hanford Site. One hundred and fifty-five earthquakes were detected in the vicinity of Wooded Island, located about eight miles north of Richland just west of the Columbia River. The Wooded Island events recorded this fiscal year were a continuation of the swarm events observed during fiscal year 2009 and reported in previous quarterly and annual reports (Rohay et al. 2009a, 2009b, 2009c, 2010a, 2010b, and 2010c). Most events were considered minor (coda-length magnitude [Mc] less than 1.0) with the largest event recorded on February 4, 2010 (3.0Mc). The estimated depths of the Wooded Island events are shallow (averaging approximately 1.5 km deep) placing the swarm within the Columbia River Basalt Group. Based upon the last two quarters (Q3 and Q4) data, activity at the Wooded Island

  6. Temporal properties of seismicity and largest earthquakes in SE Carpathians

    Directory of Open Access Journals (Sweden)

    S. Byrdina

    2006-01-01

    Full Text Available In order to estimate the hazard rate distribution of the largest seismic events in Vrancea, South-Eastern Carpathians, we study temporal properties of historical and instrumental catalogues of seismicity. First, on the basis of Generalized Extreme Value theory we estimate the average return period of the largest events. Then, following Bak et al. (2002 and Corral (2005a, we study scaling properties of recurrence times between earthquakes in appropriate spatial volumes. We come to the conclusion that the seismicity is temporally clustered, and that the distribution of recurrence times is significantly different from a Poisson process even for times largely exceeding corresponding periods of foreshock and aftershock activity. Modeling the recurrence times by a gamma distributed variable, we finally estimate hazard rates with respect to the time elapsed from the last large earthquake.

  7. Toward automatic classification of rockslides in continuous seismic data

    Science.gov (United States)

    Dammeier, Franziska; Hammer, Conny; Moore, Jeffrey; Haslinger, Florian; Loew, Simon

    2013-04-01

    Large rock slope failures often occur without warning and are among the most destructive and dangerous natural events in alpine regions. With growing settlement and development in alpine areas, efficient identification and rapid response to rockslide hazards becomes increasingly critical. Our ultimate goal is near-real-time automated identification of rockslide signals in continuous seismic data, using the network of broadband stations of the Swiss Seismological Service. Even in densely settled Switzerland, large rockslides may go unnoticed for weeks, presenting a number of secondary hazards that rapid event identification from seismic data may help mitigate. Additionally, a complete catalogue of rockslides can aid in the identification of rockslide triggers. Apart from detecting rockslide seismic signals, automatic classification into several event subcategories, e.g. rock falls or rock avalanches, may be feasible. We use the Hidden Markov Toolkit (HTK), originally developed for speech processing, in which the stochastic classifier of hidden Markov models is used to handle the variable signals of rockslides with different volumes or failure processes. Additionally, the approach used in this study allows to create an event model using only a single rockslide seismic signal and some hours of background noise recording. As large rockslides are a rare occurrence, we are thus independent of previously acquired training samples. The event model is constructed from a set of feature vectors extracted from the seismic signal in both the time and frequency domains, e.g. signal envelope, dominant frequency or bandwidth. To classify an unknown event, the probability of a section of seismic data being an event, relative to the probability of being noise, is then computed. We have assembled a set of 36 basis features that we compute in different frequency bands, leading to a total pool of 289 different features. From this pool we select at most 30 independent features for model

  8. Depth-dependence of post-seismic velocity changes in and near source area of the 2013 M7.0 Lushan earthquake revealed by S coda of repeating events

    Science.gov (United States)

    Li, Le

    2017-10-01

    I investigated postseismic velocity changes within focal area of the 2013 M7.0 Lushan earthquake using coda-wave data of repeating small earthquakes. I employed template matching and grid search methods to identify well-defined repeating earthquakes in order to minimize artifacts induced by variations in source location. I identified a total of 3 isolated patches in a two-month period after the M7.0 mainshock. I applied the coda wave interferometry technique to the waveform data of the identified repeating earthquakes to estimate velocity changes between the first and subsequent events in each cluster. Up to 0.1-0.2% velocity increase is observed from the S coda of repeating events occurred at regions surrounding the large coseismic slip area at seismogenic depths. My observations suggest that a large percent of velocity changes may occur at surface near the stations or shallow, however, healing along the propagation paths in the deep ( 5-20 km) is likely have contributed to the amount of velocity changes observed after the Lushan earthquake.

  9. Modeling of fault reactivation and induced seismicity during hydraulic fracturing of shale-gas reservoirs

    Science.gov (United States)

    We have conducted numerical simulation studies to assess the potential for injection-induced fault reactivation and notable seismic events associated with shale-gas hydraulic fracturing operations. The modeling is generally tuned toward conditions usually encountered in the Marce...

  10. A model of characteristic earthquakes and its implications for regional seismicity

    DEFF Research Database (Denmark)

    López-Ruiz, R.; Vázquez-Prada, M.; Pacheco, A.F.

    2004-01-01

    Regional seismicity (i.e. that averaged over large enough areas over long enough periods of time) has a size-frequency relationship, the Gutenberg-Richter law, which differs from that found for some seismic faults, the Characteristic Earthquake relationship. But all seismicity comes in the end from...... active faults, so the question arises of how one seismicity pattern could emerge from the other. The recently introduced Minimalist Model of Vázquez-Prada et al. of characteristic earthquakes provides a simple representation of the seismicity originating from a single fault. Here, we show...... that a Characteristic Earthquake relationship together with a fractal distribution of fault lengths can accurately describe the total seismicity produced in a region. The resulting earthquake catalogue accounts for the addition of both all the characteristic and all the non-characteristic events triggered in the faults...

  11. Comparison of seismic sources for shallow seismic: sledgehammer and pyrotechnics

    Directory of Open Access Journals (Sweden)

    Brom Aleksander

    2015-10-01

    Full Text Available The pyrotechnic materials are one of the types of the explosives materials which produce thermal, luminous or sound effects, gas, smoke and their combination as a result of a self-sustaining chemical reaction. Therefore, pyrotechnics can be used as a seismic source that is designed to release accumulated energy in a form of seismic wave recorded by tremor sensors (geophones after its passage through the rock mass. The aim of this paper was to determine the utility of pyrotechnics for shallow seismic engineering. The work presented comparing the conventional method of seismic wave excitation for seismic refraction method like plate and hammer and activating of firecrackers on the surface. The energy released by various sources and frequency spectra was compared for the two types of sources. The obtained results did not determine which sources gave the better results but showed very interesting aspects of using pyrotechnics in seismic measurements for example the use of pyrotechnic materials in MASW.

  12. Comparison of seismic sources for shallow seismic: sledgehammer and pyrotechnics

    Science.gov (United States)

    Brom, Aleksander; Stan-Kłeczek, Iwona

    2015-10-01

    The pyrotechnic materials are one of the types of the explosives materials which produce thermal, luminous or sound effects, gas, smoke and their combination as a result of a self-sustaining chemical reaction. Therefore, pyrotechnics can be used as a seismic source that is designed to release accumulated energy in a form of seismic wave recorded by tremor sensors (geophones) after its passage through the rock mass. The aim of this paper was to determine the utility of pyrotechnics for shallow seismic engineering. The work presented comparing the conventional method of seismic wave excitation for seismic refraction method like plate and hammer and activating of firecrackers on the surface. The energy released by various sources and frequency spectra was compared for the two types of sources. The obtained results did not determine which sources gave the better results but showed very interesting aspects of using pyrotechnics in seismic measurements for example the use of pyrotechnic materials in MASW.

  13. Second Quarter Hanford Seismic Report for Fiscal Year 2010

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-30

    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. The Hanford Seismic Network recorded 90 local earthquakes during the second quarter of FY 2010. Eighty-one of these earthquakes were detected in the vicinity of Wooded Island, located about eight miles north of Richland just west of the Columbia River. The Wooded Island events recorded this quarter were a continuation of the swarm events observed during the 2009 and 2010 fiscal years and reported in previous quarterly and annual reports (Rohay et al; 2009a, 2009b, 2009c, and 2010). Most of the events were considered minor (coda-length magnitude [Mc] less than 1.0) with only 1 event in the 2.0-3.0 range; the maximum magnitude event (3.0 Mc) occurred February 4, 2010 at depth 2.4 km. The average depth of the Wooded Island events during the quarter was 1.6 km with a maximum depth estimated at 3.5 km. This placed the Wooded Island events within the Columbia River Basalt Group (CRBG). The low magnitude of the Wooded Island events has made them undetectable to all but local area residents. The Hanford Strong Motion Accelerometer (SMA) network was triggered several times

  14. Development of Technology for Seismic Diagnostics of Rock Mass Conditions above the Production Working when Mining Coal Seams Prone to Geo-Dynamic Phenomena

    Directory of Open Access Journals (Sweden)

    Trifonov, O.S.

    2014-11-01

    Full Text Available Methodical guidelines to receive seismic evidence of console block cracking and hardware for continuous recording of seismic processes are developed. Energy and spectral characteristics of seismic emission for the development of tectonic destruction zones in various rock structures of the upper roof and the ability to display spatial migration of hypocenters of seismic events and their energy scale are determined. The algorithm for computation of diagnostically informative features of geodynamic hazard is worked out.

  15. Issues Related to Seismic Activity Induced by the Injection of CO2 in Deep Saline Aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Sminchak, Joel [Battelle Memorial Institute, Columbus, OH (US); Gupta, Neeraj [Battelle Memorial Institute, Columbus, OH (US); Byrer, Charles [National Energy Technology Laboratory, Pittsburgh, PA, and Morgantown, WV (US); Bergman, Perry [National Energy Technology Laboratory, Pittsburgh, PA, and Morgantown, WV (US)

    2001-05-31

    Case studies, theory, regulation, and special considerations regarding the disposal of carbon dioxide (CO2) into deep saline aquifers were investigated to assess the potential for induced seismic activity. Formations capable of accepting large volumes of CO2 make deep well injection of CO2 an attractive option. While seismic implications must be considered for injection facilities, induced seismic activity may be prevented through proper siting, installation, operation, and monitoring. Instances of induced seismic activity have been documented at hazardous waste disposal wells, oil fields, and other sites. Induced seismic activity usually occurs along previously faulted rocks and may be investigated by analyzing the stress conditions at depth. Seismic events are unlikely to occur due to injection in porous rocks unless very high injection pressures cause hydraulic fracturing. Injection wells in the United States are regulated through the Underground Injection Control (UIC) program. UIC guidance requires an injection facility to perform extensive characterization, testing, and monitoring. Special considerations related to the properties of CO2 may have seismic ramifications to a deep well injection facility. Supercritical CO2 liquid is less dense than water and may cause density-driven stress conditions at depth or interact with formation water and rocks, causing a reduction in permeability and pressure buildup leading to seismic activity. Structural compatibility, historical seismic activity, cases of seismic activity triggered by deep well injection, and formation capacity were considered in evaluating the regional seismic suitability in the United States. Regions in the central, midwestern, and southeastern United States appear best suited for deep well injection. In Ohio, substantial deep well injection at a waste disposal facility has not caused seismic events in a seismically active area. Current

  16. Gasgeochemical indicators seismic activity

    Science.gov (United States)

    Obzhirov, Anatoly

    2017-10-01

    Laboratory of Gasgeochemistry of POI FEB RAS is studying gas distribution in lithosphere, hydrosphere and atmosphere from 1977 years. Method consist is sampling from its in expedition, take gas from samples of sediment, water and atmosphere to use method degassing and analysis gas in chromatograph, to measure CH4, C2-C4, O2, N2, H2, He and some time Rn. Gas is using like indicators to search oil-gas deposits, gas hydrate, mapping zones faults, to determine seismic activity, to calculate green house gas (CH4, CO2). The next geological, geophysics and hydro-acoustics characteristics assist which help to explain to form methane bubbles fluxes and gas hydrate in the Okhotsk Sea. The methane fluxes are mostly located in the zones faults and it increase in period seismic activity.

  17. A Percolation Perspective for Gutenburg-Richter Scaling and b-values for Fracking Assocated Seismicity

    Science.gov (United States)

    Norris, J. Q.

    2016-12-01

    Published 60 years ago, the Gutenburg-Richter law provides a universal frequency-magnitude distribution for natural and induced seismicity. The GR law is a two parameter power-law with the b-value specifying the relative frequency of small and large events. For large catalogs of natural seismicity, the observed b-values are near one, while fracking associated seismicity has observed b-values near two, indicating relatively fewer large events. We have developed a computationally inexpensive percolation model for fracking that allows us to generate large catalogs of fracking associated seismicity. Using these catalogs, we show that different power-law fitting procedures produce different b-values for the same data set. This shows that care must be taken when determining and comparing b-values for fracking associated seismicity.

  18. Automatic detection of snow avalanches in continuous seismic data using hidden Markov models

    Science.gov (United States)

    Heck, Matthias; Hammer, Conny; van Herwijnen, Alec; Schweizer, Jürg; Fäh, Donat

    2018-01-01

    Snow avalanches generate seismic signals as many other mass movements. Detection of avalanches by seismic monitoring is highly relevant to assess avalanche danger. In contrast to other seismic events, signals generated by avalanches do not have a characteristic first arrival nor is it possible to detect different wave phases. In addition, the moving source character of avalanches increases the intricacy of the signals. Although it is possible to visually detect seismic signals produced by avalanches, reliable automatic detection methods for all types of avalanches do not exist yet. We therefore evaluate whether hidden Markov models (HMMs) are suitable for the automatic detection of avalanches in continuous seismic data. We analyzed data recorded during the winter season 2010 by a seismic array deployed in an avalanche starting zone above Davos, Switzerland. We re-evaluated a reference catalogue containing 385 events by grouping the events in seven probability classes. Since most of the data consist of noise, we first applied a simple amplitude threshold to reduce the amount of data. As first classification results were unsatisfying, we analyzed the temporal behavior of the seismic signals for the whole data set and found that there is a high variability in the seismic signals. We therefore applied further post-processing steps to reduce the number of false alarms by defining a minimal duration for the detected event, implementing a voting-based approach and analyzing the coherence of the detected events. We obtained the best classification results for events detected by at least five sensors and with a minimal duration of 12 s. These processing steps allowed identifying two periods of high avalanche activity, suggesting that HMMs are suitable for the automatic detection of avalanches in seismic data. However, our results also showed that more sensitive sensors and more appropriate sensor locations are needed to improve the signal-to-noise ratio of the signals and

  19. Seismicity of the rocky mountains and Rio Grande Rift from the EarthScope Transportable Array and CREST temporary seismic networks, 2008-2010

    Science.gov (United States)

    Nakai, J. S.; Sheehan, A. F.; Bilek, S. L.

    2017-03-01

    We developed a catalog of small magnitude (ML -0.1 to 4.7) seismicity across Colorado and New Mexico from the EarthScope USArray Transportable Array and CREST (Colorado Rocky Mountains Experiment and Seismic Transects) seismic networks from 2008 to 2010 to characterize active deformation in the Rio Grande Rift. We recorded over 900 earthquakes in the Rio Grande Rift region, not including induced earthquakes and mine blasts, and find that the rift is actively deforming both broadly and in distinct regions. Seismic events that are likely induced, mostly in the Raton Basin, make up 66% of the catalog (1837 earthquakes). Neogene faults in the northern rift in north central Colorado are seismically active in the North Park Basin and northwestern Colorado. The central rift from the San Luis Basin (southern Colorado) to south of the Socorro Magma Body is the most seismically active rift region, and seismicity delineates the deformation in the Colorado Plateau transition zone, which is spatially correlated with volcanic vents, dikes, and faults within the western Jemez Lineament. The eastern Jemez Lineament is nearly aseismic and surrounded by a halo of seismicity culminating in boundaries defined by recent moderate (Mw 3.9 and Mw 3.3) earthquakes. The southern rift is characterized by diffuse seismicity in Texas and Mexico. This study provides an updated seismic catalog built with uniformity in seismometer coverage and low epicentral uncertainties ( 2 km) that allows for regional evaluation of seismicity. During this time period, clusters of seismicity and moderate magnitude earthquakes characterize deformation in a low-strain rate extensional environment.

  20. Quantitative analysis of impact-induced seismic signals by numerical modeling

    Science.gov (United States)

    Güldemeister, Nicole; Wünnemann, Kai

    2017-11-01

    We quantify the seismicity of impact events using a combined numerical and experimental approach. The objectives of this work are (1) the calibration of the numerical model by utilizing real-time measurements of the elastic wave velocity and pressure amplitudes in laboratory impact experiments; (2) the determination of seismic parameters, such as quality factor Q and seismic efficiency k, for materials of different porosity and water saturation by a systematic parameter study employing the calibrated numerical model. By means of ;numerical experiments; we found that the seismic efficiency k decreases slightly with porosity from k = 3.4 × 10-3 for nonporous quartzite to k = 2.6 × 10-3 for 25% porous sandstone. If pores are completely or partly filled with water, we determined a seismic efficiency of k = 8.2 × 10-5, which is approximately two orders of magnitude lower than in the nonporous case. By measuring the attenuation of the seismic wave with distance in our numerical experiments we determined the seismic quality factor Q to range between ∼35 for the solid quartzite and 80 for the porous dry targets. For water saturated target materials, Q is much lower, seismic efficiency into seismic magnitudes we show that the seismic magnitude of an impact event is about one order of magnitude smaller considering a water saturated target in comparison to a solid or porous target. Obtained seismic magnitudes decrease linearly with distance to the point of impact and are consistent with empirical data for distances closer to the point of impact. The seismic magnitude decreases more rapidly with distance for a water saturated material compared to a dry material.

  1. Establishing seismic design criteria to achieve an acceptable seismic margin

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, R.P. [RPK Structural Mechanics Consulting, Inc., Yorba Linda, CA (United States)

    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.

  2. The importance of earthquake interactions for injection-induced seismicity: Retrospective modeling of the Basel Enhanced Geothermal System

    Science.gov (United States)

    Catalli, Flaminia; Rinaldi, Antonio P.; Gischig, Valentin; Nespoli, Massimo; Wiemer, Stefan

    2016-05-01

    We explore the role of earthquake interactions during an injection-induced seismic sequence. We propose a model, which considers both a transient pressure and static stress redistribution due to event interactions as triggering mechanisms. By calibrating the model against observations at the Enhanced Geothermal System of Basel, Switzerland, we are able to reproduce the time behavior of the seismicity rate. We observe that considering earthquake interactions in the modeling leads to a larger number of expected seismic events (24% more) if compared to a pressure-induced seismicity only. The increase of the number of events is particularly evident after the end of the injection. We conclude that implementing a model for estimating the static stress changes due to mutual event interactions increases significantly the understanding of the process and the behavior of induced seismicity.

  3. Passive seismic monitoring at the ketzin CCS site -Magnitude estimation

    NARCIS (Netherlands)

    Paap, B.F.; Steeghs, T.P.H.

    2014-01-01

    In order to allow quantification of the strength of local micro-seismic events recorded at the CCS pilot site in Ketzin in terms of local magnitude, earthquake data recorded by standardized seismometers were used. Earthquakes were selected that occurred in Poland and Czech Republic and that were

  4. Seismicity pattern in north Sumatra– Great Nicobar region: In search ...

    Indian Academy of Sciences (India)

    though downward migration of activity and a 50-day short-term quiescence was observed before the event. The various precursors identified include post-seismic and intermediate-term quiescence of 13 and 10 years respectively, between the 1976 (magnitude 6.3) and 2002 earthquakes with two years (1990–1991) of ...

  5. Full wavefield migration: Seismic imaging using multiple scattering effects

    NARCIS (Netherlands)

    Davydenko, M.

    2016-01-01

    Seismic imaging aims at revealing the structural information of the subsurface using the reflected wavefields captured by sensors usually located at the surface. Wave propagation is a complex phenomenon and the measured data contain a set of backscattered events including not only primary

  6. Effect of geological medium on seismic signals from underground ...

    Indian Academy of Sciences (India)

    Effect of geological medium on seismic signals from underground nuclear explosion events – A case study for Baneberry site ... After the successful validation of the 3D numerical model for Baneberry site rock media, parametric studies are carried out for 1 and 8 kT yields at 100 m depth (Scaled Depths of Burst SDOB ...

  7. Using micro-seismicity and seismic velocities to map subsurface geologic and hydrologic structure within the Coso geothermal field, California

    Science.gov (United States)

    Kaven, Joern Ole; Hickman, Stephen H.; Davatzes, Nicholas C.

    2012-01-01

    Geothermal reservoirs derive their capacity for fluid and heat transport in large part from faults and fractures. Micro-seismicity generated on such faults and fractures can be used to map larger fault structures as well as secondary fractures that add access to hot rock, fluid storage and recharge capacity necessary to have a sustainable geothermal resource. Additionally, inversion of seismic velocities from micro-seismicity permits imaging of regions subject to the combined effects of fracture density, fluid pressure and steam content, among other factors. We relocate 14 years of seismicity (1996-2009) in the Coso geothermal field using differential travel times and simultaneously invert for seismic velocities to improve our knowledge of the subsurface geologic and hydrologic structure. We utilize over 60,000 micro-seismic events using waveform cross-correlation to augment to expansive catalog of P- and S-wave differential travel times recorded at Coso. We further carry out rigorous uncertainty estimation and find that our results are precise to within 10s of meters of relative location error. We find that relocated micro-seismicity outlines prominent, through-going faults in the reservoir in some cases. We also find that a significant portion of seismicity remains diffuse and does not cluster into more sharply defined major structures. The seismic velocity structure reveals heterogeneous distributions of compressional (Vp) and shear (Vs) wave speed, with Vp generally lower in the main field when compared to the east flank and Vs varying more significantly in the shallow portions of the reservoir. The Vp/Vs ratio appears to outline the two main compartments of the reservoir at depths of -0.5 to 1.5 km (relative to sea-level), with a ridge of relatively high Vp/Vs separating the main field from the east flank. In the deeper portion of the reservoir this ridge is less prominent. Our results indicate that high-precision relocations of micro-seismicity can provide

  8. Aging evaluation of class 1E batteries: Seismic testing

    Energy Technology Data Exchange (ETDEWEB)

    Edson, J.L. (EG and G Idaho, Inc., Idaho Falls, ID (USA))

    1990-08-01

    This report presents the results of a seismic testing program on naturally aged class 1E batteries obtained from a nuclear plant. The testing program is a Phase 2 activity resulting from a Phase 1 aging evaluation of class 1E batteries in safety systems of nuclear power plants, performed previously as a part of the US Nuclear Regulatory Commission's Nuclear Plant Aging Research Program and reported in NUREG/CR-4457. The primary purpose of the program was to evaluate the seismic ruggedness of naturally aged batteries to determine if aged batteries could have adequate electrical capacity, as determined by tests recommended by IEEE Standards, and yet have inadequate seismic ruggedness to provide needed electrical power during and after a safe shutdown earthquake (SSE) event. A secondary purpose of the program was to evaluate selected advanced surveillance methods to determine if they were likely to be more sensitive to the aging degradation that reduces seismic ruggedness. The program used twelve batteries naturally aged to about 14 years of age in a nuclear facility and tested them at four different seismic levels representative of the levels of possible earthquakes specified for nuclear plants in the United States. Seismic testing of the batteries did not cause any loss of electrical capacity. 19 refs., 29 figs., 7 tabs.

  9. How a Country-Wide Seismological Network Can Improve Understanding of Seismicity and Seismic Hazard -- The Example of Bhutan

    Science.gov (United States)

    Hetényi, G.; Diehl, T.; Singer, J.; Kissling, E. H.; Clinton, J. F.; Wiemer, S.

    2015-12-01

    The Eastern Himalayas are home to a seemingly complex seismo-tectonic evolution. The rate of instrumental seismicity is lower than the average along the orogen, there is no record of large historical events, but both paleoseismology and GPS studies point to potentially large (M>8) earthquakes. Due to the lack of a permanent seismic monitoring system in the area, our current level of understanding is inappropriate to create a reliable quantitative seismic hazard model for the region. Existing maps are based on questionable hypotheses and show major inconsistencies when compared to each other. Here we present results on national and regional scales from a 38-station broadband seismological network we operated for almost 2 years in the Kingdom of Bhutan. A thorough, state-of-the-art analysis of local and regional earthquakes builds a comprehensive catalogue that reveals significantly (2-to-3 orders of magnitude) more events than detected from global networks. The seismotectonic analysis reveals new patterns of seismic activity as well as striking differences over relatively short distances within the Himalayas, only partly explained by surface observations such as geology. We compare a priori and a posteriori (BMC) magnitude of completeness maps and show that our network was able to detect all felt events during its operation. Some of these events could be felt at surprisingly large distances. Based on our experiment and experience, we draft the pillars on which a permanent seismological observatory for Bhutan could be constructed. Such a continuous monitoring system of seismic activity could then lead to a reliable quantitative seismic hazard model for Bhutan and surrounding regions, and serve as a base to improve building codes and general preparedness.

  10. Probabilistic properties of injection induced seismicity - implications for the seismic hazard analysis

    Science.gov (United States)

    Lasocki, Stanislaw; Urban, Pawel; Kwiatek, Grzegorz; Martinez-Garzón, Particia

    2017-04-01

    -to-use functional model. In this connection, we recommend to use in hazard analyses non-parametric, kernel estimators of magnitude distribution. The earthquake occurrence process of IIS is not a Poisson process. When earthquakes' occurrences are influenced by a multitude of inducing factors, the interevent time distribution can be modelled by the Weibull distribution supporting a negative ageing property of the process. When earthquake occurrences are due to a specific injection activity, the earthquake rate directly depends on the injection rate and responds immediately to the changes of the injection rate. Furthermore, this response is not limited only to correlated variations of the seismic activity but it also concerns significant changes of the shape of interevent time distribution. Unlike the event rate, the shape of magnitude distribution does not exhibit correlation with the injection rate. This work was supported within SHEER: "Shale Gas Exploration and Exploitation Induced Risks" project funded from Horizon 2020 - R&I Framework Programme, call H2020-LCE 16-2014-1 and within statutory activities No3841/E-41/S/2016 of Ministry of Science and Higher Education of Poland.

  11. Communication during an evolving seismic sequence

    Science.gov (United States)

    Mucciarelli, M.; Camassi, R.

    2012-04-01

    Since October 2011 a seismic swarm is affecting the Pollino mountain range, southern Italy. At the abstract submission date the sequence is still ongoing, with more than 500 events with M>1, at least 40 well perceived by the population and a maximum magnitude at 3.6. The area was hit by a magnitude 5.7 event in 1998 that caused one dead, some injured and widespread damage in at least six municipalities. The population main fear is that a large event could follow the seismic swarm as it occurred at L'Aquila in 2009. Among the initiatives taken by Civil Protection at national and regional level, it was decided to try to implement at local scale two communication projects that were thought for "peace time" and not for dissemination during a seismic crisis: the "Terremoto-Io non rischio" project for general public and the "EDURISK" project for school children. The main lesson learned during the first months of the activity are: 1) it is possible to take advantage of the increased awareness and risk perception from the population to attract more citizen toward topics that could go unnoticed otherwise; 2) the Civil Protection volunteers could be a very effective mean to reach a large amount of the population, provided they are carefully trained especially when children are involved; 3) the expectations about earthquake prediction raised from media without any scientific support proved to be the most difficult to be tackled: to overcome this bias risk education in "peace time" is absolutely essential; 4) door-to-door communication is perceived much better than official press release on newspapers; 5) training of volunteers must be limited to a few basic information, with special attention to the local context.

  12. Synthetic seismicity for the San Andreas fault

    Directory of Open Access Journals (Sweden)

    S. N. Ward

    1994-06-01

    Full Text Available Because historical catalogs generally span only a few repetition intervals of major earthquakes, they do not provide much constraint on how regularly earthquakes recur. In order to obtain better recurrence statistics and long-term probability estimates for events M ? 6 on the San Andreas fault, we apply a seismicity model to this fault. The model is based on the concept of fault segmentation and the physics of static dislocations which allow for stress transfer between segments. Constraints are provided by geological and seismological observations of segment lengths, characteristic magnitudes and long-term slip rates. Segment parameters slightly modified from the Working Group on California Earthquake Probabilities allow us to reproduce observed seismicity over four orders of magnitude. The model yields quite irregular earthquake recurrence patterns. Only the largest events (M ? 7.5 are quasi-periodic; small events cluster. Both the average recurrence time and the aperiodicity are also a function of position along the fault. The model results are consistent with paleoseismic data for the San Andreas fault as well as a global set of historical and paleoseismic recurrence data. Thus irregular earthquake recurrence resulting from segment interaction is consistent with a large range of observations.

  13. Seismic survey considerations in glaciology

    OpenAIRE

    Hofstede, Coen

    2015-01-01

    Seismic surveying of glaciers give both englacial and subglacial physical information and is as such an important tool in glaciology. In comparison with the collection of radar data, mainly performed from airborne platforms, seismic data acquisition is a time consuming process practiced in small survey areas and used less frequent. Over the last six years, AWI developed an effective strategy to collect seismic data on glaciers, ice sheets and ice shelves, at a high production rate with a smal...

  14. Perseids permanent seismic downhole system

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    PERSEIDS{sup TM} describes a permanent seismic downhole system. In that system, geo-phones are either cemented or mounted on tubing and coupled to the casing through a bow-string. Perseids{sup TM} is ideal for both passive and active seismic monitoring, to visualize bypass areas, gas cap and aquifer expansion. It can be combined with {mu}SICS{sup TM} software to record, process and interpret micro-seismic activity.

  15. Earthquake sources and seismic hazard in Southeastern Sicily

    Directory of Open Access Journals (Sweden)

    R. Rigano

    2001-06-01

    Full Text Available A study of some earthquakes (M > 5.3 affecting Southeastern Sicily was performed to define their seismic sources and to estimate seismic hazard in the region. An analysis of historical reports allowed us to reassess intensities of the 1542, 1693, 1818, 1848 and 1990 earthquakes by using the new European Macroseismic Scale ’98. The new intensity data were used to define parameters and the orientation of seismic sources. The sources obtained were compared with the ones computed using the MCS intensities retrieved from the Catalogue of Strong Italian Earthquakes. The adopted procedure gives results that are statistically significant, but both the epicentre location and source azimuth, in some cases, are strongly affected by the azimuthal gap in the intensity distribution. This is evident mainly for the 1693 January earthquakes. For these earthquakes the macroseismic data uncertainty gives significantly different solutions, and does not allow the events to be associated with known active faults. By handling the new estimated intensity data and using the site seismic histories, the seismic hazard for some localities was calculated. The highest probability of occurrence, for destructive events (I = 10, was obtained in the area between Catania, Lentini and Augusta, suggesting that the seismogenic sources are located near the Ionian coast.

  16. Next generation seismic fragility curves for California bridges incorporating the evolution in seismic design philosophy

    Science.gov (United States)

    Ramanathan, Karthik Narayan

    Quantitative and qualitative assessment of the seismic risk to highway bridges is crucial in pre-earthquake planning, and post-earthquake response of transportation systems. Such assessments provide valuable knowledge about a number of principal effects of earthquakes such as traffic disruption of the overall highway system, impact on the regions’ economy and post-earthquake response and recovery, and more recently serve as measures to quantify resilience. Unlike previous work, this study captures unique bridge design attributes specific to California bridge classes along with their evolution over three significant design eras, separated by the historic 1971 San Fernando and 1989 Loma Prieta earthquakes (these events affected changes in bridge seismic design philosophy). This research developed next-generation fragility curves for four multispan concrete bridge classes by synthesizing new knowledge and emerging modeling capabilities, and by closely coordinating new and ongoing national research initiatives with expertise from bridge designers. A multi-phase framework was developed for generating fragility curves, which provides decision makers with essential tools for emergency response, design, planning, policy support, and maximizing investments in bridge retrofit. This framework encompasses generational changes in bridge design and construction details. Parameterized high-fidelity three-dimensional nonlinear analytical models are developed for the portfolios of bridge classes within different design eras. These models incorporate a wide range of geometric and material uncertainties, and their responses are characterized under seismic loadings. Fragility curves were then developed considering the vulnerability of multiple components and thereby help to quantify the performance of highway bridge networks and to study the impact of seismic design principles on the performance within a bridge class. This not only leads to the development of fragility relations

  17. Selecting the seismic HRA approach for Savannah River Plant PRA revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Papouchado, K.; Salaymeh, J. [eds.] [Westinghouse Savannah River Co., Aiken, SC (United States); Wingo, H.E.; Benhardt, H.C.; van Buijtenen, C.M.; Mitts, T.M. [Battelle Pacific Northwest Labs., Richland, WA (United States)

    1993-10-01

    The Westinghouse Savannah River Company (WSRC) has prepared a level I probabilistic risk assessment (PRA), Rev. 0 of reactor operations for externally-initiated events including seismic events. The SRS PRA, Rev. 0 Seismic HRA received a critical review that expressed skepticism with the approach used for human reliability analysis because it had not been previously used and accepted in other published PRAs. This report provides a review of published probabilistic risk assessments (PRAs), the associated methodology guidance documents, and the psychological literature to identify parameters important to seismic human reliability analysis (HRA). It also describes a recommended approach for use in the Savannah River Site (SRS) PRA. The SRS seismic event PRA performs HRA to account for the contribution of human errors in the accident sequences. The HRA of human actions during and after a seismic event is an area subject to many uncertainties and involves significant analyst judgment. The approach recommended by this report is based on seismic HRA methods and associated issues and concerns identified from the review of these referenced documents that represent the current state-of-the- art knowledge and acceptance in the seismic HRA field.

  18. SeisRockHT - Seismic Rockfall Monitoring in the Hohe Tauern region

    Science.gov (United States)

    Binder, Daniel; Hartmeyer, Ingo; Keuschnig, Markus; Mertl, Stefan; Lenhardt, Wolfgang

    2016-04-01

    SeisRockHT focuses on open hardware and free software applied for scientific long-term monitoring strategies in harsh environments. In detail, SeisRockHT aims at the establishment of two seismic networks to quantitatively observe seismicity and rockfall events at high alpine north faces. Due to the rare character of rockfall events, a continuous and long-term observation strategy is targeted. The long-term perspective is assured through the project partner of the Austrian seismic service who will include SeisRockHT networks when the project is completed. Two study sites were selected for monitoring: the Kitzsteinhorn and the Hohe Sonnblick exhibiting two different scales of monitoring networks. The smaller scaled Kitzsteinhorn investigation site is closely related to bedrock permafrost processes, whereas the larger-scaled Sonnblick investigation site aims a classic alpine north face. SeisRockHT will develop a suite of optimum methods for characterization, detection and localization of the seismic events recorded at the two sites. Beside analysis of discrete seismic events, ambient seismic noise analysis promises a closer insight into rockfall precursory seismic characteristics.Based on the high quality complementary data delivered by already established long-term monitoring projects at the two sites, potential rockfall triggers will be suggested.

  19. 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.

  20. Factors affecting seismic response of submarine slopes

    Directory of Open Access Journals (Sweden)

    G. Biscontin

    2006-01-01

    Full Text Available The response of submerged slopes on the continental shelf to seismic or storm loading has become an important element in the risk assessment for offshore structures and 'local' tsunami hazards worldwide. The geological profile of these slopes typically includes normally consolidated to lightly overconsolidated soft cohesive soils with layer thickness ranging from a few meters to hundreds of meters. The factor of safety obtained from pseudo-static analyses is not always a useful measure for evaluating the slope response, since values less than one do not necessarily imply slope failure with large movements of the soil mass. This paper addresses the relative importance of different factors affecting the response of submerged slopes during seismic loading. The analyses use a dynamic finite element code which includes a constitutive law describing the anisotropic stress-strain-strength behavior of normally consolidated to lightly overconsolidated clays. The model also incorporates anisotropic hardening to describe the effect of different shear strain and stress histories as well as bounding surface principles to provide realistic descriptions of the accumulation of the plastic strains and excess pore pressure during successive loading cycles. The paper presents results from parametric site response analyses on slope geometry and layering, soil material parameters, and input ground motion characteristics. The predicted maximum shear strains, permanent deformations, displacement time histories and maximum excess pore pressure development provide insight of slope performance during a seismic event.

  1. Discriminatory characteristics of seismic gaps in Himalaya

    Directory of Open Access Journals (Sweden)

    H.N. Srivastava

    2015-04-01

    Full Text Available Contrary to most of the earlier theories that great earthquakes (Mw 8.5 or even larger may occur anywhere along the Indian plate boundary assuming uniform strain accumulation, this paper proposes two types of gaps with discriminatory characteristics. The new gaps were initially identified from earthquakes of magnitude 6, whose return periods in Himalaya vary between 20 and 30 years and are well within the period of reliable instrumental data of about 100 years. These gaps were then integrated with the largest magnitude event in instrumental era and historical times; information on paleoseismicity, micro-seismicity data, GPS-based geodetic observations and the tectonic features. The regions where great/major earthquakes (Mw 8 or larger have occurred in the past are classified as seismic gap of category 1, namely Kashmir, west Himachal Pradesh (Kangra, Uttarakhand to Dharachulla, central Nepal to Bihar, Shillong, Arunachal gap including Assam–Tibet–Myanmar syntaxis. On the other hand, the second category of seismic gap includes Jammu–Kishtwar block, east Himachal Pradesh, western Nepal (excluding Dharachulla region and Sikkim–Bhutan where history of large earthquakes is not available. In these gaps, the largest earthquake magnitude is smaller (7–7.5 and the recurrence interval for earthquakes of same magnitude is larger as compared to category 1 gaps.

  2. Flat lens for seismic waves

    CERN Document Server

    Brule, Stephane; Guenneau, Sebastien

    2016-01-01

    A prerequisite for achieving seismic invisibility is to demonstrate the ability of civil engineers to control seismic waves with artificially structured soils. We carry out large-scale field tests with a structured soil made of a grid consisting of cylindrical and vertical holes in the ground and a low frequency artificial source (< 10 Hz). This allows the identification of a distribution of energy inside the grid, which can be interpreted as the consequence of an effective negative refraction index. Such a flat lens reminiscent of what Veselago and Pendry envisioned for light opens avenues in seismic metamaterials to counteract the most devastating components of seismic signals.

  3. SEISMIC RISK CARTOGRAPHIC VISUALIZATION FOR CRISIS MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Nina I. Frolova

    2014-01-01

    Full Text Available Earthquake loss estimations before future events and following strong earthquakesin emergency mode and their corresponding visualization are extremely important for properdecision on preventive measures and effective response in order to save lives and properties. The paper addresses the methodological issues of seismic risk and vulnerability assessment, mapping with GIS technology application. Requirements for simulation models,databases used at different levels, as well as ways of visualizations oriented for EmergencyManagement Agencies, as well federal and local authorities are discussed. Examples ofmapping at the different levels: global, country, region and urban one are given and theinfluence of input data uncertainties on the reliability of loss computations is analyzed.

  4. Seismic Hazards Studies for Minuteman Missile Wings.

    Science.gov (United States)

    1980-09-09

    activity to ground motion at the site of interest, it is necessary to have a means of predicting ground motion at the site as a function of arthquake ...xs of ., arthquakes rported in th , -entral Uni!,d States. A.. )n g -he events reported in this region are several of the largest e’vents to have occur...source area ;i maxintum niagnitude ’ arthquake if 6. 5 M was allowed. The seismic risk curves for this case are given in Figurres 23 arid 24 as the

  5. Probabilistic Seismic Hazard assessment in Albania

    Science.gov (United States)

    Muco, B.; Kiratzi, A.; Sulstarova, E.; Kociu, S.; Peci, V.; Scordilis, E.

    2002-12-01

    Albania is one of the coutries with highest sesimicity in Europe.The history of instrumental monitoring of seismicity in this country started since 1968 with the setting up of the first seismographic station of Tirana and more effectively after the beginning of the operation of the Albanian Seismological Network in 1976. There is a rich evidence that during two thousands years Albania has been hit by many disastrous earthquakes. The highest magnitude estimated is 7.2. After the end of Communist era and opening of the country, a boom of constructions started in Albania continuing even now. It makes more indispensabile the producing of accurate seismic hazard maps for preventing the damages of future probable earthquakes. Some efforts have already been done in seismic hazard assessment(Sulstarova et al., 1980; Kociu, 2000; Muco et al., 2002). In this approach, the probabilistic technique has been used in one joint work between Seismological Institute of Tirana, Albania and Department of Geophysics of Aristotle University of Thessaloniki, Greece, into the framework of NATO SfP project "SeisAlbania". The earthquake catalogue adopted was specifically conceived for this seismic hazard analysis and contains 530 events with magnitude M>4.5 from the year 58 up to 2000. We divided the country in 8 seismotectonic zones giving for them the most representative fault characteristics. The computer code used for hazard calculation was OHAZ, developed from the Geophysical Survey of Slovenia and the attenuation models used were Ambraseys et al., 1996; Sabetta and Pugliese, 1996 and Margaris et al., 2001. The hazard maps are obtained for 100, 475, 2375 and 4746 return periods, for rock soil condition. Analyzing the map of PGA values for a return period of 475 years, there are separated 5 zones with different escalation of PGA values: 1)the zone with PGA (0.20 - 0.24 g) 1.8 percent of Albanian territory, 2)the zone with PGA (0.16 - 0.20 g) 22.6 percent of Albanian territory, 3)the

  6. Features, Events, and Processes: Disruptive Events

    Energy Technology Data Exchange (ETDEWEB)

    P. Sanchez

    2004-11-08

    The purpose of this analysis report is to evaluate and document the inclusion or exclusion of the disruptive events features, events, and processes (FEPs) with respect to modeling used to support the total system performance assessment for license application (TSPA-LA). A screening decision, either ''Included'' or ''Excluded,'' is given for each FEP, along with the technical basis for screening decisions. This information is required by the U.S. Nuclear Regulatory Commission (NRC) at 10 CFR 63.114 (d), (e), and (f) [DIRS 156605]. The FEPs addressed in this report deal with both seismic and igneous disruptive events, such as fault displacements through the repository and an igneous intrusion into the repository. For included FEPs, this analysis summarizes the implementation of the FEP in TSPA-LA (i.e., how the FEP is included). For excluded FEPs, this analysis provides the technical basis for exclusion from TSPA-LA (i.e., why the FEP is excluded). Previous versions of this report were developed to support the total system performance assessments (TSPA) for various prior repository designs. This revision addresses the repository design for the license application (LA).

  7. Seismic retrofit guidelines for Utah highway bridges.

    Science.gov (United States)

    2009-05-01

    Much of Utahs population dwells in a seismically active region, and many of the bridges connecting transportation lifelines predate the rigorous seismic design standards that have been developed in the past 10-20 years. Seismic retrofitting method...

  8. The influence of backfill on seismicity

    CSIR Research Space (South Africa)

    Hemp, DA

    1990-09-01

    Full Text Available , that the seismicity has been reduced in areas where backfill had been placed. A factor complicating the evaluation of backfill on seismicity is the effect of geological structures on seismicity....

  9. A future for drifting seismic networks

    Science.gov (United States)

    Simons, F. J.; Nolet, G.; Babcock, J.

    2007-12-01

    event (for seismic tomography, that is), determine a GPS location, and transmit the waveforms to a satellite. In this presentation we discuss the progress made in this field by our group. More specifically, we discuss the results of preliminary tests conducted off-shore La Jolla in 2003 and 2004, as well as just-in results from a third successful, in situ, test completed in August 2007. We will draw attention to design issues and bottlenecks and the need for and features of sophisticated onboard data analysis software which we have developed and tested. We will chart a road map of the way to our ultimate goal: a worldwide array of MERMAID floating hydrophones, on the scale of the current international land-based seismic arrays. This, we believe, has the potential to progressively eliminate the discrepancies in spatial coverage that currently result in seismic Earth models that are very poorly resolved in places.

  10. Forecasting Induced Seismicity In Deep Geothermal Energy Projects

    Science.gov (United States)

    Király, Eszter; Gischig, Valentin; Karvounis, Dimitrios; Heiniger, Lukas; Wiemer, Stefan

    2014-05-01

    The decision to phase out nuclear power in Switzerland by 2034 accelerated research on deep geothermal energy, which has the ability to contribute to long-term energy resources. Induced seismicity occurring during early stimulation periods in deep geothermal projects of past years in Switzerland, however, clearly document our limited understanding of the processes at depth that lead to significant seismic hazard and that may influence public acceptance of future projects. Controlling induced seismicity related to deep geothermal projects with adaptive warning systems require models that are forward looking, dynamically updated on the fly as new data arrive and probabilistic in the sense that the inherent uncertainties in our understanding of the processes and in the required model parameters. We currently develop a fully coupled non-linear hydraulic-seismic 3D model joint with a hazard assessment procedure. The goal is to improve the forecasting skill owing to validated physical constraints. As a first step, we seek to answer the question: is it possible to forecast the seismic response of the geothermal site during and after stimulation based on observed seismicity and hydraulic data? Our goal is to find the most suitable model to date for forecasting induced micro-seismicity and unexpected large events in geothermal systems. In order to do so, available stochastic and hybrid models are tested and ranked such as Epidemic Type Aftershock Sequence models, models developed by Shapiro and his research group and two types of geomechanical seed models incorporating linear and non-linear fluid flow. The aim is to balance model prediction performance and model complexity: which parameters are necessary to forecast seismicity well, and which are eventually those that increase model complexity but do not give better results. All tests are performed on the Basel 2006 dataset. Testing is carried out along the guidelines of the Collaboratory for the Study of Earthquake

  11. KrakMon: Seismic signals recorded at Krakatau Volcano, Indonesia

    Science.gov (United States)

    Ibs-von Seht, M.; Hoffmann-Rothe, A.; Kniess, R.

    2005-12-01

    A recently installed multi-parameter monitoring system on the Krakatau volcanic island complex located in the Sunda Strait (Indonesia) provides continuous broadband records of seismic data. We present here an overview of the different signal types identified and first results of an automated detection and classification procedure for volcano-seismic events recorded at Krakatau volcano. In comparison to seismic signals known from other volcanoes, an unusually high portion of high-frequency content is observed in the spectra of the Krakatau signals. This observation applies to short-term volcano-tectonic (VT) events as well as to continuous tremor signals: most VT events show significant energy at frequencies above 30Hz, harmonic signals last almost continuously for days and show spectral peaks at distinct frequencies well above15Hz. The automated detection and classification procedure bases a spectrogram analysis of volcano-seismic signals using a straight-forward pattern recognition approach: a suitable threshold operator generates a binary representation of the spectrogram which is processed by a contour finding algorithm. The resulting contour-polygons define regions in the spectrogram containing significant spectral energy and their shapes reveal information about the respective volcano-seismic signals. By the extraction of stable shape-describing properties from the polygons and their statistical analysis it is attempted to identify different classes of signal types. A comparison of the resulting signal types with those determined visually by the operator can improve classification schemes for volcano-seismic signals and contribute to defining the activity status of Krakatau and other volcanoes.

  12. Probabilistic Seismic Hazard Assessment for Northeast India Region

    Science.gov (United States)

    Das, Ranjit; Sharma, M. L.; Wason, H. R.

    2016-08-01

    Northeast India bounded by latitudes 20°-30°N and longitudes 87°-98°E is one of the most seismically active areas in the world. This region has experienced several moderate-to-large-sized earthquakes, including the 12 June, 1897 Shillong earthquake ( M w 8.1) and the 15 August, 1950 Assam earthquake ( M w 8.7) which caused loss of human lives and significant damages to buildings highlighting the importance of seismic hazard assessment for the region. Probabilistic seismic hazard assessment of the region has been carried out using a unified moment magnitude catalog prepared by an improved General Orthogonal Regression methodology (Geophys J Int, 190:1091-1096, 2012; Probabilistic seismic hazard assessment of Northeast India region, Ph.D. Thesis, Department of Earthquake Engineering, IIT Roorkee, Roorkee, 2013) with events compiled from various databases (ISC, NEIC,GCMT, IMD) and other available catalogs. The study area has been subdivided into nine seismogenic source zones to account for local variation in tectonics and seismicity characteristics. The seismicity parameters are estimated for each of these source zones, which are input variables into seismic hazard estimation of a region. The seismic hazard analysis of the study region has been performed by dividing the area into grids of size 0.1° × 0.1°. Peak ground acceleration (PGA) and spectral acceleration ( S a) values (for periods of 0.2 and 1 s) have been evaluated at bedrock level corresponding to probability of exceedance (PE) of 50, 20, 10, 2 and 0.5 % in 50 years. These exceedance values correspond to return periods of 100, 225, 475, 2475, and 10,000 years, respectively. The seismic hazard maps have been prepared at the bedrock level, and it is observed that the seismic hazard estimates show a significant local variation in contrast to the uniform hazard value suggested by the Indian standard seismic code [Indian standard, criteria for earthquake-resistant design of structures, fifth edition, Part

  13. Third 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.

    2009-09-30

    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. The Hanford Seismic Network recorded 771 local earthquakes during the third quarter of FY 2009. Nearly all of these earthquakes were detected in the vicinity of Wooded Island, located about eight miles north of Richland just west of the Columbia River. The Wooded Island events recorded this quarter is a continuation of the swarm events observed during the January – March 2009 time period and reported in the previous quarterly report (Rohay et al, 2009). The frequency of Wooded Island events has subsided with 16 events recorded during June 2009. Most of the events were considered minor (magnitude (Mc) less than 1.0) with 25 events in the 2.0-3.0 range. The estimated depths of the Wooded Island events are shallow (averaging less than 1.0 km deep) with a maximum depth estimated at 2.2 km. This places the Wooded Island events within the Columbia River Basalt Group (CRBG). The low magnitude of the Wooded Island events has made them undetectable to all but local area residents. However, some Hanford employees working within a few miles of the area of highest activity

  14. Automated classification of seismic sources in a large database: a comparison of Random Forests and Deep Neural Networks.

    Science.gov (United States)

    Hibert, Clement; Stumpf, André; Provost, Floriane; Malet, Jean-Philippe

    2017-04-01

    In the past decades, the increasing quality of seismic sensors and capability to transfer remotely large quantity of data led to a fast densification of local, regional and global seismic networks for near real-time monitoring of crustal and surface processes. This technological advance permits the use of seismology to document geological and natural/anthropogenic processes (volcanoes, ice-calving, landslides, snow and rock avalanches, geothermal fields), but also led to an ever-growing quantity of seismic data. This wealth of seismic data makes the construction of complete seismicity catalogs, which include earthquakes but also other sources of seismic waves, more challenging and very time-consuming as this critical pre-processing stage is classically done by human operators and because hundreds of thousands of seismic signals have to be processed. To overcome this issue, the development of automatic methods for the processing of continuous seismic data appears to be a necessity. The classification algorithm should satisfy the need of a method that is robust, precise and versatile enough to be deployed to monitor the seismicity in very different contexts. In this study, we evaluate the ability of machine learning algorithms for the analysis of seismic sources at the Piton de la Fournaise volcano being Random Forest and Deep Neural Network classifiers. We gather a catalog of more than 20,000 events, belonging to 8 classes of seismic sources. We define 60 attributes, based on the waveform, the frequency content and the polarization of the seismic waves, to parameterize the seismic signals recorded. We show that both algorithms provide similar positive classification rates, with values exceeding 90% of the events. When trained with a sufficient number of events, the rate of positive identification can reach 99%. These very high rates of positive identification open the perspective of an operational implementation of these algorithms for near-real time monitoring of

  15. The Deelen infrasound array for recording sonic booms and events of CTBT interest

    NARCIS (Netherlands)

    Evers, L.; de Bree, H.E.; Haak, H.W.; Koers, A.A.

    2000-01-01

    The Seismology Division of the Royal Netherlands Meteorological Institute (KNMI) has build up expertise in infrasound measurements by investigating low frequency events in order to distinguish between seismic and sonic events. KNMI operates, amongst others, a sixteen element microbarometer array

  16. The Deelen infrasound array for recording sonic booms and events of CTBT interest

    NARCIS (Netherlands)

    Evers, L.G.; de Bree, H.E.; Haak, H.W.; Koers, A.A.

    2000-01-01

    The Seismology Division of the Royal Netherlands Meteorological Institute (KNMI) has built up expertise in infrasound measurements by investigating low frequency events in order to distinguish between seismic and sonic events. KNMI operates, amongst others, a sixteen element microbarometer array

  17. Automatic determination of seismic phase arrival times

    Science.gov (United States)

    Kang, T. S.; Kim, M.; Rhie, J.

    2016-12-01

    Determination of P- and S-wave phase arrival times is significant factors in microseismic detection and thus hypocenter source inversion. If analysts try to pick P- and S-wave phase arrival times of microseismic events manually, they are at risk for inconsistency in picking due to subjective determination of P- and S-wave phase arrival times among them and get to spend too much time in doing the job. This study presents a method for the automatic detection of event and determination of arrival times of seismic phases. An implementation of the method is consisting of five steps. The first is the initial declaration of an event in continuous seismic data using a characteristic function which is also designed specifically in this study. The second is the automatic determination of P-wave phase arrival time using the normalized squared-envelope function. The third is the application of three-axis rotation using an energy ratio among three-component seismograms of the event. The fourth is the automatic determination of S-wave phase arrival time. The final step is the removal of falsely determined time in some records using the Wadati diagram which plots S-P times against P-wave phase arrival times over stations used in the picking stage. Application of the method to the continuous waveform data from a temporary broadband seismograph network consisting of 20 stations distributed in Jeju Island shows that the automatic event detection and determination of phase arrival times are carried out with accuracy.

  18. Mine seismicity and the Comprehensive Nuclear Test Ban Treaty

    Energy Technology Data Exchange (ETDEWEB)

    Chiappetta, F. [Blasting Analysis International, Allentown, PA (United States); Heuze, F.; Walter, W. [Lawrence Livermore National Lab., CA (United States); Hopler, R. [Powderman Consulting Inc., Oxford, MD (United States); Hsu, V. [Air Force Technical Applications Center, Patrick AFB, FL (United States); Martin, B. [Thunder Basin Coal Co., Wright, WY (United States); Pearson, C. [Los Alamos National Lab., NM (United States); Stump, B. [Southern Methodist Univ., Dallas, TX (United States); Zipf, K. [Univ. of New South Wales (Australia)

    1998-12-09

    Surface and underground mining operations generate seismic ground motions which are created by chemical explosions and ground failures. It may come as a surprise to some that the ground failures (coal bumps, first caves, pillar collapses, rockbursts, etc.) can send signals whose magnitudes are as strong or stronger than those from any mining blast. A verification system that includes seismic, infrasound, hydroacoustic and radionuclide sensors is being completed as part of the CTBT. The largest mine blasts and ground failures will be detected by this system and must be identified as distinct from signals generated by small nuclear explosions. Seismologists will analyze the seismic records and presumably should be able to separate them into earthquake-like and non earthquake-like categories, using a variety of so-called seismic discriminants. Non-earthquake essentially means explosion- or implosion-like. Such signals can be generated not only by mine blasts but also by a variety of ground failures. Because it is known that single-fired chemical explosions and nuclear explosion signals of the same yield give very similar seismic records, the non-earthquake signals will be of concern to the Treaty verification community. The magnitude of the mine-related events is in the range of seismicity created by smaller nuclear explosions or decoupled tests, which are of particular concern under the Treaty. It is conceivable that legitimate mining blasts or some mine-induced ground failures could occasionally be questioned. Information such as shot time, location and design parameters may be all that is necessary to resolve the event identity. In rare instances where the legitimate origin of the event could not be resolved by a consultation and clarification procedure, it might trigger on On-Site Inspection (OSI). Because there is uncertainty in the precise location of seismic event as determined by the International Monitoring System (IMS), the OSI can cover an area of up to 1

  19. Assessing the seismic coupling of shallow continental faults and its impact on seismic hazard estimates: a case-study from Italy

    Science.gov (United States)

    Carafa, Michele M. C.; Valensise, Gianluca; Bird, Peter

    2017-04-01

    We propose an objective and reproducible algorithmic path to forecast seismicity in Italy from long-term deformation models. These models are appropriate for Italy and its neighbouring countries and seas thanks to the availability of rich, reliable and regularly updated historical earthquake and seismogenic fault databases, and to the density of permanent GPS stations. However, so far little has been done to assess the seismic coupling of Italian active faults, that is to quantify their ability to release earthquakes. This must be determined in order to use geodetic and active faulting observations in alternative seismicity models, to overcome possible limitations of the earthquake record for the assessment of seismic hazard. We use a probabilistic method to assign upper crustal earthquakes from the historical catalogue to their presumed causative faults, then collect all the events into three subcatalogues corresponding to the compressional, extensional and strike-slip faulting classes. We then determine the parameters of their Gutenberg-Richter frequency/magnitude relations using maximum-likelihood methods and integrate these distributions to estimate the long-term seismic moment rate for each class. Finally, we compare these seismicity rates to the long-term tectonic deformation based on GPS data, thus determining the coupled thickness (and estimating seismic coupling) for each fault class. We find that in our study region the seismic coupling and the related coupled thickness is on average two times larger for extensional than for compressional faults. As for the spatial distribution of earthquake rates, a larger number of events is predicted for the extensional settings of the Apennines chain, in agreement with the inferred seismic coupling but also with the long-term strain rates. We also find that the frequency/magnitude distributions indicate that the largest earthquakes occur in extensional settings, whereas compressional faults are expected to host

  20. Seismogenic zonation and seismic hazard estimates in a Southern Italy area (Northern Apulia characterised by moderate seismicity rates

    Directory of Open Access Journals (Sweden)

    V. Del Gaudio

    2009-02-01

    Full Text Available The northernmost part of Apulia, in Southern Italy, is an emerged portion of the Adriatic plate, which in past centuries was hit by at least three disastrous earthquakes and at present is occasionally affected by seismic events of moderate energy. In the latest seismic hazard assessment carried out in Italy at national scale, the adopted seismogenic zonation (named ZS9 has defined for this area a single zone including parts of different structural units (chain, foredeep, foreland. However significant seismic behaviour differences were revealed among them by our recent studies and, therefore, we re-evaluated local seismic hazard by adopting a zonation, named ZNA, modifying the ZS9 to separate areas of Northern Apulia belonging to different structural domains. To overcome the problem of the limited datasets of historical events available for small zones having a relatively low rate of earthquake recurrence, an approach was adopted that integrates historical and instrumental event data. The latter were declustered with a procedure specifically devised to process datasets of low to moderate magnitude shocks. Seismicity rates were then calculated following alternative procedural choices, according to a "logic tree" approach, to explore the influence of epistemic uncertainties on the final results and to evaluate, among these, the importance of the uncertainty in seismogenic zonation. The comparison between the results obtained using zonations ZNA and ZS9 confirms the well known "spreading effect" that the use of larger seismogenic zones has on hazard estimates. This effect can locally determine underestimates or overestimates by amounts that make necessary a careful reconsideration of seismic classification and building code application.

  1. Elastic-Wavefield Seismic Stratigraphy: A New Seismic Imaging Technology

    Energy Technology Data Exchange (ETDEWEB)

    Bob A. Hardage; Milo M. Backus; Michael V. DeAngelo; Sergey Fomel; Khaled Fouad; Robert J. Graebner; Paul E. Murray; Randy Remington; Diana Sava

    2006-07-31

    The purpose of our research has been to develop and demonstrate a seismic technology that will provide the oil and gas industry a better methodology for understanding reservoir and seal architectures and for improving interpretations of hydrocarbon systems. Our research goal was to expand the valuable science of seismic stratigraphy beyond the constraints of compressional (P-P) seismic data by using all modes (P-P, P-SV, SH-SH, SV-SV, SV-P) of a seismic elastic wavefield to define depositional sequences and facies. Our objective was to demonstrate that one or more modes of an elastic wavefield may image stratal surfaces across some stratigraphic intervals that are not seen by companion wave modes and thus provide different, but equally valid, information regarding depositional sequences and sedimentary facies within that interval. We use the term elastic wavefield stratigraphy to describe the methodology we use to integrate seismic sequences and seismic facies from all modes of an elastic wavefield into a seismic interpretation. We interpreted both onshore and marine multicomponent seismic surveys to select the data examples that we use to document the principles of elastic wavefield stratigraphy. We have also used examples from published papers that illustrate some concepts better than did the multicomponent seismic data that were available for our analysis. In each interpretation study, we used rock physics modeling to explain how and why certain geological conditions caused differences in P and S reflectivities that resulted in P-wave seismic sequences and facies being different from depth-equivalent S-wave sequences and facies across the targets we studied.

  2. Automatic Seismic Signal Processing

    Science.gov (United States)

    1982-02-04

    81-04 4 February 1982 AUTOMATIC SEISMIC SIGNAL PROCESSING FINAL TECHNICAL REPORT i j Contract F08606-80.C-0021" PREPARED BY ILKKA NOPONEN, ROBERT SAX...PERFORMING ORG. REPORT NUMBER SAS-FR-81-04 7. AUTHOR(e) a. CONTRACT OR GRANT NUMBER(e) F08606- 80-C-0021 ILKKA NOPONEN, ROBERT SAX AND F 6 C0 STEVEN...observed, as also Swindell and Snell (1977), that the distribu- tion of x was slightly skewed, we used the median of x instead of aver- age of x for U(x

  3. Seismicity and Design Codes in Chile: Characteristic Features and a Comparison with Some of the Provisions of the Romanian Seismic Design Code

    Directory of Open Access Journals (Sweden)

    Diana ENE

    2010-07-01

    Full Text Available A brief history and the characteristics of the seismic region and events in Chile reveal interesting indices in understanding the present day Chilean seismic design code. The paper points out some of the most important prescriptions in the Chilean code that could have led to the relatively reduced number of casualties at the seismic event on February 27th, 2010. By comparing the Chilean code to the Romanian one, the goal is to underline the differences and the similarities regarding both the conceptual and the formal aspects. Observations are pointed out by means of comparative diagrams of significant parameters. Based on statistics of recorded damage published after the earthquake, some comments are made on the importance of the quality of seismic codes and of the effectiveness of their enforcement.

  4. 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.

  5. Seismic evidence of a second submarine eruption in the north of El Hierro Island

    Science.gov (United States)

    Ortiz, R.; Berrocoso, M.; de la Cruz-Reyna, S.; Marrero, J. M.; Garcia, A.

    2012-04-01

    From the July 19, 2011 an increase of seismicity, accompanied by a remarkable process of deformation, was detected on the island of El Hierro. This reactivation process, instrumental and scientifically monitored, culminates in the occurrence of a submarine eruption, with the emergence of a strong tremor signal, in the south of the island on October 10, 2011. Both processes (unrest and eruption) have different phases and behaviors clearly evidenced by the deformation and seismicity. This work is the result of an exhaustive analysis of seismic signals from three stations deployed on the island of El Hierro(CTAB and CTIG (IGN) and REST (CSIC)), in order to explain the behavior of the volcanic system responsible for the submarine eruption of Las Calmas sea and its evolution, as well as evidence of a second submarine eruption in the north of the island (ElGolfo). The spectral content of signals from the seismic stations in the north of the island (CTIG and CTAB) and the area around the eruption (REST) has the dominant peak at different frequencies. The amplitude modulations of the seismic noise evolved differently in CTAB and CTIG than REST being particularly significant changes in amplitude and frequency after the occurrence of events of magnitude greater than 4. The evolution of the volcano-tectonic cumulative seismic energy shows the occurrence of two similar eruptive episodes, in which two phases can be distinguished. The first phase of both cycles has a constant rate with seismic events of magnitude less than 3 to reach the energy of 10 ^ 11 Joule. From that moment the magnitude grows rapidly exceeding magnitude 4. In the second phase the seismic events are mainly located in the south of the island, before the onset of visual evidences of the eruption (October 11, 2011) and later (November 2011) the seismic events are mainly located in the north of the island, where no visible signs have been detected. In both cases the appearance or changes in the tremor signal

  6. Neural analysis of seismic data: applications to the monitoring of Mt. Vesuvius

    Directory of Open Access Journals (Sweden)

    Antonietta M. Esposito

    2013-11-01

    Full Text Available The computing techniques currently available for the seismic monitoring allow advanced analysis. However, the correct event classification remains a critical aspect for the reliability of real time automatic analysis. Among the existing methods, neural networks may be considered efficient tools for detection and discrimination, and may be integrated into intelligent systems for the automatic classification of seismic events. In this work we apply an unsupervised technique for analysis and classification of seismic signals recorded in the Mt. Vesuvius area in order to improve the automatic event detection. The examined dataset contains about 1500 records divided into four typologies of events: earthquakes, landslides, artificial explosions, and “other” (any other signals not included in the previous classes. First, the Linear Predictive Coding (LPC and a waveform parametrization have been applied to achieve a significant and compact data encoding. Then, the clustering is obtained using a Self-Organizing Map (SOM neural network which does not require an a-priori classification of the seismic signals, groups those with similar structures, providing a simple framework for understanding the relationships between them. The resulting SOM map is separated into different areas, each one containing the events of a defined type. This means that the SOM discriminates well the four classes of seismic signals. Moreover, the system will classify a new input pattern depending on its position on the SOM map. The proposed approach can be an efficient instrument for the real time automatic analysis of seismic data, especially in the case of possible volcanic unrest.

  7. Seismic hazard maps of Italy

    Directory of Open Access Journals (Sweden)

    A. Rebez

    1998-06-01

    Full Text Available The Italian "Gruppo Nazionale per la Difesa dai Terremoti" has conducted a project in recent years for assessing seismic hazard in the national territory to be used as a basis for the revision of the current seismic zonation. In this project the data on the major earthquakes were reassessed and a new earthquake data file prepared. Definition of a seismotectonic model for the whole territory, based on a structural-kinematic analysis of Italy and the surrounding regions, led to the definition of 80 seismogenic zones, for which the geological and seismic characteristics were determined. Horizontal PGA and macroseismic intensity were used as seismicity parameters in the application of the Cornell probabilistic approach. The main aspects of the seismic hazard assessment are here described and the results obtained are presented and discussed. The maps prepared show the various aspects of seismic hazard which need to be considered for a global view of the problem. In particular, those with a 475-year return period, in agreement with the specifications of the new seismic Eurocode EC8, can be considered basic products for a revision of the present national seismic zonation.

  8. Seismic attenuation imaging with causality

    NARCIS (Netherlands)

    Hak, B.; Mulder, W.A.

    2010-01-01

    Seismic data enable imaging of the Earth, not only of velocity and density but also of attenuation contrasts. Unfortunately, the Born approximation of the constant-density visco-acoustic wave equation, which can serve as a forward modelling operator related to seismic migration, exhibits an

  9. Seismic microzonation of Bangalore, India

    Indian Academy of Sciences (India)

    encompassing Bangalore Mahanagara. Palike (BMP) has been chosen as the study area. Seismic hazard analysis and microzonation of. Bangalore are addressed in three parts: in the first part, estimation of seismic hazard is done using seismotectonic and geological information. Second part deals with site ...

  10. Seismic imaging with incoherent wavefields

    NARCIS (Netherlands)

    Berkhout, A.J.; Verschuur, D.J.; Blacquière, G.

    2009-01-01

    In blended seismic acquisition incoherent source arrays are used to generate the seismic response. The blended shot records can be directly fed into a shot record migration scheme with a more advanced imaging condition. Blended shot records can also be simulated in the processing phase. In the

  11. Proposed uniform building code seismic risk zone revision in southeast Idaho

    Energy Technology Data Exchange (ETDEWEB)

    Arendts, J. G.; Gorman, V. W.; Guenzler, R. C.; Miller, L. G.

    1979-01-01

    A number of scientific studies concerning geology and seismicity in the Southeast Idaho region have been conducted within the last ten years. The results of these studies, as well as some recent national seismic risk evaluations, indicate that the present Uniform Building Code (UBC) seismic risk zone classification for a major portion of the Southeast Idaho region is excessively high. The objective of the work presented herein is utilization of the scientific evidence to propose a revised UBC seismic risk zone map for Southeastern Idaho where a portion of the present seismic risk Zone 3 is revised to Zone 2. Regional geological information, including known and suspected faults, is presented. A comprehensive summary of magnitude and location of recorded regional earthquake epicenters and their relation to the proposed UBC seismic zone modification is presented. Correlation between the geology of the region and recorded seismic events with the proposed UBC zone revision is shown. A rationale, based on recognized seismic risk studies, is developed for location of the proposed UBC seismic risk zone lines. Correlation with existing national risk zones is shown and inherent conservatisms are discussed. Finally, the detailed location of the proposed revised zone lines is presented. It is noted that the revision affects Southeastern Idaho and small regions of Southwestern Montana and Northwestern Utah. 17 figures, 2 tables.

  12. Intermediate-term variations in 200 years seismicity of south of Iran

    Directory of Open Access Journals (Sweden)

    Majid Nemati

    2016-05-01

    Full Text Available Remarkable variations in moderate–large seismicity during the last two centuries in Zagros and eastern Iran seismotectonic provinces have chronically been investigated, in this study. The time variations of seismic hazards [macroseismic maximum intensity and scalar moment of the earthquakes (I0 > IV; M > 5.0] were investigated as seismic behaviours for the study area. According to the fact that damage of an earthquake is strongly influenced by the depth of the event, depths of some of the historical and pre-instrumental earthquakes were reasonably estimated using macroseismic data. Processing the data of earthquakes reliably demonstrated that relatively quiet periods have happened and have subsequently been followed by active periods with various durations in south of Iran. According to both patterns of the temporal variations of seismicity and the seismic hazards, we are within a decelerating seismic deformation and we may expect an accelerating seismic deformation in the next decades. Moreover, in both areas, we discovered a manifest migration of the seismicity from the northeast to the southwest region that is a significant phenomenon in seismology. Finally, two seismic gaps at specific time periods in northwest of Zagros, Dasht-e Bayaz and Ferdows areas at the eastern Iran were also found.

  13. HANFORD DOUBLE SHELL TANK THERMAL AND SEISMIC PROJECT SEISMIC ANALYSIS OF HANFORD DOUBLE SHELL TANKS

    Energy Technology Data Exchange (ETDEWEB)

    MACKEY TC; RINKER MW; CARPENTER BG; HENDRIX C; ABATT FG

    2009-01-15

    M&D Professional Services, Inc. (M&D) is under subcontract to Pacific Northwest National Laboratories (PNNL) to perform seismic analysis of the Hanford Site Double-Shell Tanks (DSTs) in support of a project entitled Double-Shell Tank (DST) Integrity Project - DST Thermal and Seismic Analyses. The original scope of the project was to complete an up-to-date comprehensive analysis of record of the DST System at Hanford in support of Tri-Party Agreement Milestone M-48-14. The work described herein was performed in support of the seismic analysis of the DSTs. The thermal and operating loads analysis of the DSTs is documented in Rinker et al. (2004). Although Milestone M-48-14 has been met, Revision I is being issued to address external review comments with emphasis on changes in the modeling of anchor bolts connecting the concrete dome and the steel primary tank. The work statement provided to M&D (PNNL 2003) required that a nonlinear soil structure interaction (SSI) analysis be performed on the DSTs. The analysis is required to include the effects of sliding interfaces and fluid sloshing (fluid-structure interaction). SSI analysis has traditionally been treated by frequency domain computer codes such as SHAKE (Schnabel, et al. 1972) and SASSI (Lysmer et al. 1999a). Such frequency domain programs are limited to the analysis of linear systems. Because of the contact surfaces, the response of the DSTs to a seismic event is inherently nonlinear and consequently outside the range of applicability of the linear frequency domain programs. That is, the nonlinear response of the DSTs to seismic excitation requires the use of a time domain code. The capabilities and limitations of the commercial time domain codes ANSYS{reg_sign} and MSC Dytran{reg_sign} for performing seismic SSI analysis of the DSTs and the methodology required to perform the detailed seismic analysis of the DSTs has been addressed in Rinker et al (2006a). On the basis of the results reported in Rinker et al

  14. The natural seismic hazard and induced seismicity of the european HDR (hot dry rock) geothermal energy project at Soultz-sous-Forets (Bas-Rhin, France); Alea sismique naturel et sismicite induite du projet geothermique europeen RCS (roche chaude seche) de Soultz-sous-Forets (Bas-Rhin, France)

    Energy Technology Data Exchange (ETDEWEB)

    Helm, J.A.

    1996-06-07

    Development of the Soultz-sous-Forets HDR (Hot Dry Rock) geothermal energy project will involve important fluid injections which will induce micro-seismic events. This thesis discusses the natural seismicity of the region and induced seismicity associated with fluid injections. A catalogue of all historical and instrument seismicity of the Soultz-sous-Forets (SSF) region has been compiled. This seismicity does not correspond to movements along the major tectonic features of the region. The area around SSF has been identified as being one where high heat flow corresponds to low seismicity. The largest well documented seismic event in the region which took place in 1952 had an epicentral intensity of VI. All important data pertaining to the series of seismic events which took place in the region from August to October 1952 have been collected and are presented. This work details the installation and operation of a permanent 3 station network of accelerometers and seismometers around the HDR site. Also the installation and operation of a mobile network of vertical seismometers during fluid injections. 167 micro-seismic events were recorded on the surface network, with magnitudes from -0.5 to 1.9. The preferential alignment of the micro-seismic cloud is N160 deg. Individual focal mechanisms of the larger seismic events correspond to an extensional tectonic regime. Stress inversion of P wave polarities indicates that the maximum stress is vertical and the intermediate and minimum stress axes horizontal. The largest of the horizontal stresses is orientated N124 deg and the smallest N34 deg. Induced seismic movement is taking place on pre-existing fractures controlled by the in situ stress seismic movement is taking place on pre-existing tectonic fractures controlled by the in situ stress field, and the largest of the induced events had a magnitude 1.9. This level of seismicity does not pose any environmental hazard to the region around Soultz-sous-Forets. (author) 151

  15. Advances in Rotational Seismic Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Pierson, Robert [Applied Technology Associates, Albuquerque, NM (United States); Laughlin, Darren [Applied Technology Associates, Albuquerque, NM (United States); Brune, Robert [Applied Technology Associates, Albuquerque, NM (United States)

    2016-10-19

    Rotational motion is increasingly understood to be a significant part of seismic wave motion. Rotations can be important in earthquake strong motion and in Induced Seismicity Monitoring. Rotational seismic data can also enable shear selectivity and improve wavefield sampling for vertical geophones in 3D surveys, among other applications. However, sensor technology has been a limiting factor to date. The US Department of Energy (DOE) and Applied Technology Associates (ATA) are funding a multi-year project that is now entering Phase 2 to develop and deploy a new generation of rotational sensors for validation of rotational seismic applications. Initial focus is on induced seismicity monitoring, particularly for Enhanced Geothermal Systems (EGS) with fracturing. The sensors employ Magnetohydrodynamic (MHD) principles with broadband response, improved noise floors, robustness, and repeatability. This paper presents a summary of Phase 1 results and Phase 2 status.

  16. Seismic methods for verifying nuclear test bans

    Science.gov (United States)

    Sykes, Lynn R.; Evernden, Jack F.; Cifuentes, Inés

    1983-10-01

    Seismological research of the past 25 years related to verification of a Threshold Test Ban Treaty (TIBT) indicates that a treaty banning nuclear weapons tests in all environments, including underground explosions, can be monitored with high reliablility down to explosions of very small size (about one kiloton). There would be high probability of successful identification of explosions of that size even if elaborate measures were taken to evade detection. Seismology provides the principal means of detecting, locating and identifying underground explosions and of determining their yields. We discuss a number of methods for identifying detected seismic events as being either explosions or earthquakes including the event's location, depth and spectral character. The seismic waves generated by these two types of sources differ in a number of fundamental ways that can be utilized for identification or discrimination. All of the long-standing issues related to a comprehensive treaty were resolved in principle (and in may cases in detail) in negotiations between the U.S., the U.S.S.R. and Britian from 1977 to 1980. Those negotiations have not resumed since 1980. Inadequate seismic means of verifying a CTBT, Soviet cheating on the 150-kt limit of the Treshold Test Ban Treaty of 1976, and the need to develop and test new nuclear weapons were cited in 1982 by the U.S. government as reasons for not continuing negotiations for a CTBT. The first two reservations, which depend heavily on seismological information, are not supported scientifically. A CTBT could help to put a lid on the seemingly endless testing of new generations of nuclear weapons by both superpowers.

  17. Micromachined silicon seismic transducers

    Energy Technology Data Exchange (ETDEWEB)

    Barron, C.C.; Fleming, J.G.; Sniegowski, J.J.; Armour, D.L.; Fleming, R.P.

    1995-08-01

    Batch-fabricated silicon seismic transducers could revolutionize the discipline of CTBT monitoring by providing inexpensive, easily depolyable sensor arrays. Although our goal is to fabricate seismic sensors that provide the same performance level as the current state-of-the-art ``macro`` systems, if necessary one could deploy a larger number of these small sensors at closer proximity to the location being monitored in order to compensate for lower performance. We have chosen a modified pendulum design and are manufacturing prototypes in two different silicon micromachining fabrication technologies. The first set of prototypes, fabricated in our advanced surface- micromachining technology, are currently being packaged for testing in servo circuits -- we anticipate that these devices, which have masses in the 1--10 {mu}g range, will resolve sub-mG signals. Concurrently, we are developing a novel ``mold`` micromachining technology that promises to make proof masses in the 1--10 mg range possible -- our calculations indicate that devices made in this new technology will resolve down to at least sub-{mu}G signals, and may even approach to 10{sup {minus}10} G/{radical}Hz acceleration levels found in the low-earth-noise model.

  18. Seismic hazard assessment of the cultural heritage sites: A case study in Cappadocia (Turkey)

    Science.gov (United States)

    Seyrek, Evren; Orhan, Ahmet; Dinçer, İsmail

    2014-05-01

    Turkey is one of the most seismically active regions in the world. Major earthquakes with the potential of threatening life and property occur frequently here. In the last decade, over 50,000 residents lost their lives, commonly as a result of building failures in seismic events. The Cappadocia region is one of the most important touristic sites in Turkey. At the same time, the region has been included to the Word Heritage List by UNESCO at 1985 due to its natural, historical and cultural values. The region is undesirably affected by several environmental conditions, which are subjected in many previous studies. But, there are limited studies about the seismic evaluation of the region. Some of the important historical and cultural heritage sites are: Goreme Open Air Museum, Uchisar Castle, Ortahisar Castle, Derinkuyu Underground City and Ihlara Valley. According to seismic hazard zonation map published by the Ministry of Reconstruction and Settlement these heritage sites fall in Zone III, Zone IV and Zone V. This map show peak ground acceleration or 10 percent probability of exceedance in 50 years for bedrock. In this connection, seismic hazard assessment of these heritage sites has to be evaluated. In this study, seismic hazard calculations are performed both deterministic and probabilistic approaches with local site conditions. A catalog of historical and instrumental earthquakes is prepared and used in this study. The seismic sources have been identified for seismic hazard assessment based on geological, seismological and geophysical information. Peak Ground Acceleration (PGA) at bed rock level is calculated for different seismic sources using available attenuation relationship formula applicable to Turkey. The result of the present study reveals that the seismic hazard at these sites is closely matching with the Seismic Zonation map published by the Ministry of Reconstruction and Settlement. Keywords: Seismic Hazard Assessment, Probabilistic Approach

  19. Are seismic hazard assessment errors and earthquake surprises unavoidable?

    Science.gov (United States)

    Kossobokov, Vladimir

    2013-04-01

    Why earthquake occurrences bring us so many surprises? The answer seems evident if we review the relationships that are commonly used to assess seismic hazard. The time-span of physically reliable Seismic History is yet a small portion of a rupture recurrence cycle at an earthquake-prone site, which makes premature any kind of reliable probabilistic statements about narrowly localized seismic hazard. Moreover, seismic evidences accumulated to-date demonstrate clearly that most of the empirical relations commonly accepted in the early history of instrumental seismology can be proved erroneous when testing statistical significance is applied. Seismic events, including mega-earthquakes, cluster displaying behaviors that are far from independent or periodic. Their distribution in space is possibly fractal, definitely, far from uniform even in a single segment of a fault zone. Such a situation contradicts generally accepted assumptions used for analytically tractable or computer simulations and complicates design of reliable methodologies for realistic earthquake hazard assessment, as well as search and definition of precursory behaviors to be used for forecast/prediction purposes. As a result, the conclusions drawn from such simulations and analyses can MISLEAD TO SCIENTIFICALLY GROUNDLESS APPLICATION, which is unwise and extremely dangerous in assessing expected societal risks and losses. For example, a systematic comparison of the GSHAP peak ground acceleration estimates with those related to actual strong earthquakes, unfortunately, discloses gross inadequacy of this "probabilistic" product, which appears UNACCEPTABLE FOR ANY KIND OF RESPONSIBLE SEISMIC RISK EVALUATION AND KNOWLEDGEABLE DISASTER PREVENTION. The self-evident shortcomings and failures of GSHAP appeals to all earthquake scientists and engineers for an urgent revision of the global seismic hazard maps from the first principles including background methodologies involved, such that there becomes: (a) a

  20. Seismic safety in nuclear-waste disposal

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, D.W.; Towse, D.

    1979-04-26

    Seismic safety is one of the factors that must be considered in the disposal of nuclear waste in deep geologic media. This report reviews the data on damage to underground equipment and structures from earthquakes, the record of associated motions, and the conventional methods of seismic safety-analysis and engineering. Safety considerations may be divided into two classes: those during the operational life of a disposal facility, and those pertinent to the post-decommissioning life of the facility. Operational hazards may be mitigated by conventional construction practices and site selection criteria. Events that would materially affect the long-term integrity of a decommissioned facility appear to be highly unlikely and can be substantially avoided by conservative site selection and facility design. These events include substantial fault movement within the disposal facility and severe ground shaking in an earthquake epicentral region. Techniques need to be developed to address the question of long-term earthquake probability in relatively aseismic regions, and for discriminating between active and extinct faults in regions where earthquake activity does not result in surface ruptures.

  1. Scaling of Seismic Memory with Earthquake Size

    CERN Document Server

    Zheng, Zeyu; Tenenbaum, Joel; Podobnik, Boris; Stanley, H Eugene

    2011-01-01

    It has been observed that the earthquake events possess short-term memory, i.e. that events occurring in a particular location are dependent on the short history of that location. We conduct an analysis to see whether real-time earthquake data also possess long-term memory and, if so, whether such autocorrelations depend on the size of earthquakes within close spatiotemporal proximity. We analyze the seismic waveform database recorded by 64 stations in Japan, including the 2011 "Great East Japan Earthquake", one of the five most powerful earthquakes ever recorded which resulted in a tsunami and devastating nuclear accidents. We explore the question of seismic memory through use of mean conditional intervals and detrended fluctuation analysis (DFA). We find that the waveform sign series show long-range power-law anticorrelations while the interval series show long-range power-law correlations. We find size-dependence in earthquake auto-correlations---as earthquake size increases, both of these correlation beha...

  2. Induced seismicity in the Tbilisi region, East Georgia

    Science.gov (United States)

    Melikadze, G.; Chelidze, T.; Jimsheladze, T.

    2009-04-01

    The paper gives an overview on the underground fluid and geodynamical response to oil production processes and discusses the possible oil pumping-induced seismicity in the Tbilisi region, Georgia. The intensive oil production in 80-s disturbs the regime of the central hydrothermal deposit and causes depletion and desalination of springs. Analysis of data in the period of intensive increase in oil production rate at the Samgori-Ninotsminda oil field in 1975 and its drastic decrease in 1985 points to close connection of hydrological regime of thermal water in boreholes #1 Botanic-Garden (1 BG) with oil production level: fast increase of oil production leads to drastic decrease of debit in the central borehole to almost zero and 20-meters decrease of water level in the with some relatively long (month) time lags. Water debit in 1BG begin slow recovery after termination of pumping. In Tbilisi region during 1970-1989 was produced more than 5.1010 to kg of oil so according to existing statistics the level of extraction is close to critical for appearance of induced seismicity. The stress change induced by hydrocarbon extraction is as a rule small, but the deviatory stress exceeding 0.01 MPa may trigger seismic activity. In order to distinguish the seismohydraulic effect we plotted the seismic activity (SA) versus time in the time interval, covering periods before (1960-1970), during (1970-1989) and after termination (1990-2004) of oil production interval. To exclude the effect of local seismic network changes during 1960-2004 only the catalog of the Tbilisi Seismic Observatory (TSO), where the registration conditions were not changed in this period has been used. In the analyzed catalog were included events occurred within circular area of radius 50 km around TSO. Three types of TSO catalog were analyzed: TSO1 included all events, recorded at the observatory, even smallest ones; TSO2 included only the events of magnitude M  2.5; TSO3 included the events of magnitude M

  3. Seismic modeling study of Vostok lake East Antartica

    Science.gov (United States)

    Carcione, J. M.; Gei, D.; Camerlenghi, A.

    2003-04-01

    Vostok Lake is located in East Antarctica between 76.2oS/102oE and 78.4oS/108oE (extending about 230 km to the north of Vostok Station), beneath nearly 4 km of glacial ice. This lake, believed to be the largest subglacial lake, has been surveyed by airbone 60 MHz radio-echo soundings (Kapitsa et al., 1996) and seismic surveys (Kapitsa et al., 1996; Masolov et al., 1999). In this work, we study the seismic visibility of the lake using seismic modeling and analyze the amplitude variations with offset (AVA) characteristics of the ice/water and water/sediment interfaces by computing the corresponding reflection and refraction coefficients. There is a need of suitable models for studying the seismic response of subglacial lakes and planning seismic reflection surveys. The geological model is defined by using available seismic information and poroelastic models that take into account the in-situ conditions of the different layers versus temperature and pressure. The methodology involves rock-physics models of the shallow layer (firn), the ice sheet and the lake sediments, numerical simulation of synthetic seismograms, ray tracing, tau-p transform, and AVA analysis, based on the theoretical reflection coefficients. The reflection seismograms show a set of straight events and the two reflection events associated with the top and bottom of the lake. Theoretical AVA analysis of these reflections indicates that, at near offsets, the PP-wave anomaly is negative for the ice/water interface and constant for the water/sediment interface. This behavior is confirmed by AVA analysis of the synthetic data set. This study shows that subglacial lakes can be identified by using seismic methods. Moreover, the methodology provides a tool for designing suitable seismic surveys. largeReferences} begin{description} Carcione, J.M. and Gei, D., Seismic modeling study of a subglacial lake, submitted to Geophysical Prospecting. Kapitsa, A. P., Ridley, J. K., Robin, G. de Q., Siegert, M. J., and

  4. Seismic hazard from induced seismicity: effect of time-dependent hazard variables

    Science.gov (United States)

    Convertito, V.; Sharma, N.; Maercklin, N.; Emolo, A.; Zollo, A.

    2012-12-01

    of the peak-ground motion parameters (e.g., magnitude, geometrical spreading and anelastic attenuation). Moreover, we consider both the inter-event and intra-event components of the standard deviation. For comparison, we use the same dataset analyzed by Convertito et al. (2012), and for successive time windows we perform the regression analysis to infer the time-dependent coefficients of the GMPE. After having tested the statistical significance of the new coefficients and having verified a reduction in the total standard deviation, we introduce the new model in the hazard integral. Hazard maps and site-specific analyses in terms of a uniform hazard spectrum are used to compare the new results with those obtained in our previous study to investigate which coefficients and which components of the total standard deviation do really matter for refining seismic hazard estimates for induced seismicity. Convertito et al. (2012). From Induced Seismicity to Direct Time-Dependent Seismic Hazard, BSSA 102(6), doi:10.1785/0120120036.

  5. 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.

  6. Automatic detection of alpine rockslides in continuous seismic data using hidden Markov models

    Science.gov (United States)

    Dammeier, Franziska; Moore, Jeffrey R.; Hammer, Conny; Haslinger, Florian; Loew, Simon

    2016-02-01

    Data from continuously recording permanent seismic networks can contain information about rockslide occurrence and timing complementary to eyewitness observations and thus aid in construction of robust event catalogs. However, detecting infrequent rockslide signals within large volumes of continuous seismic waveform data remains challenging and often requires demanding manual intervention. We adapted an automatic classification method using hidden Markov models to detect rockslide signals in seismic data from two stations in central Switzerland. We first processed 21 known rockslides, with event volumes spanning 3 orders of magnitude and station event distances varying by 1 order of magnitude, which resulted in 13 and 19 successfully classified events at the two stations. Retraining the models to incorporate seismic noise from the day of the event improved the respective results to 16 and 19 successful classifications. The missed events generally had low signal-to-noise ratio and small to medium volumes. We then processed nearly 14 years of continuous seismic data from the same two stations to detect previously unknown events. After postprocessing, we classified 30 new events as rockslides, of which we could verify three through independent observation. In particular, the largest new event, with estimated volume of 500,000 m3, was not generally known within the Swiss landslide community, highlighting the importance of regional seismic data analysis even in densely populated mountainous regions. Our method can be easily implemented as part of existing earthquake monitoring systems, and with an average event detection rate of about two per month, manual verification would not significantly increase operational workload.

  7. Seismic activations of different level in Altay-Sayan mounting area

    Science.gov (United States)

    Emanov, Dr.; Emanov, A. A.; Leskova, E. V.

    2009-04-01

    Seismicity of Altai-Sayan mountain area is well coordinated in its structure with block texture. Background seismicity organizes itself in mountain hollow framing with a high repeatability. The hollows in quiet state are aseismatic. The exception is Belino-Busingol system of depressions, where two different types of seismicity are in contact: rift processes with earthquake concentration in hollows and collision processes with seismicity around the hollows. Tree depressions of this zone (Busingol, Belin, Terehol) are transition zone for different seismicity types, and in this zone earthquakes are recorded both in hollow, and in mountain framing. Not infrequently in some geological structures of this region seismic activations occur, breaking regularity of background seismicity. As often as not there are aftershock processes, generated by large earthquakes. Sometimes this is cluster seismicity. Investigations, carried out with temporary stations in zone of Ureg-Nur earthquake, allowed to be fixed that background seismicity of Ureg-Nur earthquake area is ordered in conformity with block structure typically for Altai, when earthquakes are concentrated in mountain hollow framing. Four separated event groups different by behavior and confined to different blocks of mountain framing of hollows, have been allocated. The seismic process is confined not to deep break, but to interiors of mountain massifs. Busingol earthquake of 27.12.1991, Ms=6.5 generated unique seismic activation, which is not agree with frameworks of aftershock process. Already fifteen years seismic regime of this zone doesn't conform to background regime. The distinctive feature of this activation is pulsating regime. An effect of spatial shift of pulsing activity from Busingol depression deep into Shishhid plateau is noted. An areal migration of events from depression edge to the place of pulsing activity rise had been revealed. The earthquake cluster in Uksug block of West Sayan in 2001 is a prominent

  8. Use of Double Difference techniques to reveal seismicity and crustal structure patterns in the Galati region (SE part of Romania)

    Science.gov (United States)

    Borleanu, Felix; Rogozea, Maria; Liviu, Manea; Popa, Mihaela; Radulian, Mircea

    2017-04-01

    A large seismic swarm occurred between 15 August and 5 November 2013 in the outer side of the SE Carpathians at about 30 km north-west of Galati city. The National Institute for Earth Physics installed in the epicentral area 4 temporary stations to enhance the seismic monitoring and location capability. Although the magnitude of the events did not exceed 4.0 (according to seismic bulletins computed by the Romanian National Data Centre), their effects were unusually high, being felt by the population and creating panic throughout the duration of the swarm. Taking into account the large number of seismic events occurred during the swarm and the events sporadically produced in the same region after the swarm cessation until the present time, as well as the relatively dense seismic network monitoring the area, we applied Double Difference techniques to reveal the regional seismicity and crustal structure patterns. The results show alignments of the seismic events along the crustal faults orientated between Sf. Gheorghe and Peceneaga-Camena Faults and significant seismic velocity inhomogeneity from east to west for the upper part of the crust.

  9. 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

  10. Back-Projecting Volcano and Geyser Seismic Signals to Sources

    Science.gov (United States)

    Kelly, C. L.; Lawrence, J. F.; Ebinger, C. J.

    2015-12-01

    Volcanic and hydrothermal systems are generally characterized by persistent, low-amplitude seismic "noise" with no clear onset or end. Outside of active eruptions and earthquakes, which tend to occur only a small fraction of the time, seismic records and spectrograms from these systems are dominated by long-duration "noise" (typically around 1-5Hz) generated by ongoing processes in the systems' subsurface. Although it has been shown that these low-amplitude signals can represent a series of overlapping low-magnitude displacements related to fluid and volatile movement at depth, because of their "noisy" properties compared to typical active or earthquake sources they are difficult to image using traditional seismic techniques (i.e. phase-picking). In this study we present results from applying a new ambient noise back-projection technique to improve seismic source imaging of diffuse signals found in volcanic and hydrothermal systems. Using this new method we show how the distribution of all seismic sources - particularly sources associated with volcanic tremor - evolves during a proposed intrusion in early June 2010 at Sierra Negra Volcano on the Galápagos Archipelago off the coast of Ecuador. We use a known velocity model for the region (Tepp et al., 2014) to correlate and back-project seismic signals from all available receiver-pairs to potential subsurface source locations assuming bending raypaths and accounting for topography. We generate 4D time-lapsed images of the source field around Sierra Negra before, during and after the proposed intrusion and compare the consistency of our observations with previously identified seismic event locations and tomography results from the same time period. Preliminary results from applying the technique to a dense grid of geophones surrounding a periodically erupting geyser at El Tatio Geyser Field in northern Chile (>2000 eruptions recorded) will also be presented.

  11. Waveform Fingerprinting for Efficient Seismic Signal Detection

    Science.gov (United States)

    Yoon, C. E.; OReilly, O. J.; Beroza, G. C.

    2013-12-01

    Cross-correlating an earthquake waveform template with continuous waveform data has proven a powerful approach for detecting events missing from earthquake catalogs. If templates do not exist, it is possible to divide the waveform data into short overlapping time windows, then identify window pairs with similar waveforms. Applying these approaches to earthquake monitoring in seismic networks has tremendous potential to improve the completeness of earthquake catalogs, but because effort scales quadratically with time, it rapidly becomes computationally infeasible. We develop a fingerprinting technique to identify similar waveforms, using only a few compact features of the original data. The concept is similar to human fingerprints, which utilize key diagnostic features to identify people uniquely. Analogous audio-fingerprinting approaches have accurately and efficiently found similar audio clips within large databases; example applications include identifying songs and finding copyrighted content within YouTube videos. In order to fingerprint waveforms, we compute a spectrogram of the time series, and segment it into multiple overlapping windows (spectral images). For each spectral image, we apply a wavelet transform, and retain only the sign of the maximum magnitude wavelet coefficients. This procedure retains just the large-scale structure of the data, providing both robustness to noise and significant dimensionality reduction. Each fingerprint is a high-dimensional, sparse, binary data object that can be stored in a database without significant storage costs. Similar fingerprints within the database are efficiently searched using locality-sensitive hashing. We test this technique on waveform data from the Northern California Seismic Network that contains events not detected in the catalog. We show that this algorithm successfully identifies similar waveforms and detects uncataloged low magnitude events in addition to cataloged events, while running to completion

  12. Second 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.

    2009-07-31

    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. The Hanford Seismic Network recorded over 800 local earthquakes during the second quarter of FY 2009. Nearly all of these earthquakes were detected in the vicinity of Wooded Island, located about eight miles north of Richland just west of the Columbia River. Most of the events were considered minor (magnitude (Mc) less than 1.0) with 19 events in the 2.0-2.9 range. The estimated depths of the Wooded Island events are shallow (averaging less than 1.0 km deep) with a maximum depth estimated at 1.9 km. This places the Wooded Island events within the Columbia River Basalt Group (CRBG). The low magnitude and the shallowness of the Wooded Island events have made them undetectable to most area residents. However, some Hanford employees working within a few miles of the area of highest activity, and individuals living in homes directly across the Columbia River from the swarm center, have reported feeling some movement. The Hanford SMA network was triggered numerous times by the Wooded Island swarm events. The maximum acceleration values recorded by the SMA network were

  13. High-Resolution Analysis of Seismicity Induced at Berlín Geothermal Field, El Salvador

    Science.gov (United States)

    Kwiatek, G.; Bulut, F.; Dresen, G. H.; Bohnhoff, M.

    2012-12-01

    We investigate induced microseismic activity monitored at Berlín Geothermal Field, El Salvador, during a hydraulic stimulation. The site was monitored for a time period of 17 months using thirteen 3-component seismic stations located in shallow boreholes. Three stimulations were performed in the well TR8A with a maximum injection rate and well head pressure of 160l/s and 130bar, respectively. For the entire time period of our analysis, the acquisition system recorded 581 events with moment magnitudes ranging between -0.5 and 3.7. The initial seismic catalog provided by the operator was substantially improved: 1) We re-picked P- and S-wave onsets and relocated the seismic events using the double-difference relocation algorithm based on cross-correlation derived differential arrival time data. Forward modeling was performed using a local 1D velocity model instead of homogeneous full-space. 2) We recalculated source parameters using the spectral fitting method and refined the results applying the spectral ratio method. We investigated the source parameters and spatial and temporal changes of the seismic activity based on the refined dataset and studied the correlation between seismic activity and production. The achieved hypocentral precision allowed resolving the spatiotemporal changes in seismic activity down to a scale of a few meters. The application of spectral ratio method significantly improved the quality of source parameters in a high-attenuating and complex geological environment. Of special interest is the largest event (Mw3.7) and its nucleation process. We investigate whether the refined seismic data display any signatures that the largest event is triggered by the shut-in of the well. We found seismic activity displaying clear spatial and temporal patterns that could be easily related to the amount of water injected into the well TR8A and other reinjection wells in the investigated area. The migration of seismicity outside of injection point is observed

  14. A Fiber-Optic Borehole Seismic Vector Sensor System for Geothermal Site Characterization and Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Paulsson, Bjorn N.P. [Paulsson, Inc., Van Nuys, CA (United States); Thornburg, Jon A. [Paulsson, Inc., Van Nuys, CA (United States); He, Ruiqing [Paulsson, Inc., Van Nuys, CA (United States)

    2015-04-21

    Seismic techniques are the dominant geophysical techniques for the characterization of subsurface structures and stratigraphy. The seismic techniques also dominate the monitoring and mapping of reservoir injection and production processes. Borehole seismology, of all the seismic techniques, despite its current shortcomings, has been shown to provide the highest resolution characterization and most precise monitoring results because it generates higher signal to noise ratio and higher frequency data than surface seismic techniques. The operational environments for borehole seismic instruments are however much more demanding than for surface seismic instruments making both the instruments and the installation much more expensive. The current state-of-the-art borehole seismic instruments have not been robust enough for long term monitoring compounding the problems with expensive instruments and installations. Furthermore, they have also not been able to record the large bandwidth data available in boreholes or having the sensitivity allowing them to record small high frequency micro seismic events with high vector fidelity. To reliably achieve high resolution characterization and long term monitoring of Enhanced Geothermal Systems (EGS) sites a new generation of borehole seismic instruments must therefore be developed and deployed. To address the critical site characterization and monitoring needs for EGS programs, US Department of Energy (DOE) funded Paulsson, Inc. in 2010 to develop a fiber optic based ultra-large bandwidth clamped borehole seismic vector array capable of deploying up to one thousand 3C sensor pods suitable for deployment into ultra-high temperature and high pressure boreholes. Tests of the fiber optic seismic vector sensors developed on the DOE funding have shown that the new borehole seismic sensor technology is capable of generating outstanding high vector fidelity data with extremely large bandwidth: 0.01 – 6,000 Hz. Field tests have shown

  15. A New Search For Moonquakes In The Apollo 12 Seismic Data Set

    Science.gov (United States)

    Oberst, J.; Mizutani, H.

    Among the 12000 seismic events detected by the Apollo 12 station, more than 7000 events are listed as "Unclassified" in the Apollo Long-Period Seismic Event Catalog. We have carried out a search for "Deep Moonquakes" among these events. The sources of this most abundant moonquake type are a distinct set of 109 nests (designated as A1, A2,... A109) that repeatedly release seismic waves of strikingly similar character- istics. This suggests that "Deep Moonquakes" can be identified by a search for events of similar appearance. Cross correlation in the frequency domain was used to identify "matches" among large numbers of "Unclassified" events; and techniques were devel- oped to carry out "match tests" rapidly and with high reliability. The analysis greatly benefited from availability of computers with fast processors and large on-line disk storage, not available during the early Apollo Seismic Data analysis. A total of ap- prox. 260,000 tests were carried out, 0.2% of which came out positive, involving 608 distinct events. Approx. half of these events could be related to known moonquake nests. The number of events associated with A01, the most prolific nest, increased to 237 events (previously: 178). For other large nests, as A09 and A14, the total number of events almost doubled (now: 90 and 61, respectively). Being concerned that small nests with few members are difficult to detect with our "match tests", we made an attempt to model the efficiency of our moonquake search. Results of our models sug- gest that a large fraction, perhaps the majority, of the "Unclassified" events represent "Deep Moonquakes". An updated Apollo Long-Period Event Catalog will be of great benefit for the Japanese Lunar-A penetrator (seismometer) mission, expected to use seismic signals from the known Moonquake nests to study the Lunar interior.

  16. Usefulness of magnitude for determination of seismic shock parameters recorded by mine seismic system in Upper Silesia

    Energy Technology Data Exchange (ETDEWEB)

    Syrek, B.; Wcislo, A.

    1981-06-01

    Microseismic shock recording systems, operating in 22 coal mines in Upper Silesia, as well as the regional microseismic shock recording system determine energy of seismic events. Use of magnitude measurement instead of energy of seismic shocks would be more suitable for the microseismic systems. Selected methods of determining magnitude of seismic shocks are discussed, among others the Richter method, IASPEI method, and Bisztricsany's method of calculating magnitude on the basis of shock duration and its record by a seismograph. Mathematical formulae used to determine shock magnitude according to the three methods are given. Bisztricsany's method of magnitude calculation is easy, produces results quickly, is relatively accurate and is most suitable for the Upper Silesian recording systems. Use of the method would permit recording results to be compared to recordings in countries using the Richter scale. (7 refs.)

  17. Assessing a 3D smoothed seismicity model of induced earthquakes

    Science.gov (United States)

    Zechar, Jeremy; Király, Eszter; Gischig, Valentin; Wiemer, Stefan

    2016-04-01

    As more energy exploration and extraction efforts cause earthquakes, it becomes increasingly important to control induced seismicity. Risk management schemes must be improved and should ultimately be based on near-real-time forecasting systems. With this goal in mind, we propose a test bench to evaluate models of induced seismicity based on metrics developed by the CSEP community. To illustrate the test bench, we consider a model based on the so-called seismogenic index and a rate decay; to produce three-dimensional forecasts, we smooth past earthquakes in space and time. We explore four variants of this model using the Basel 2006 and Soultz-sous-Forêts 2004 datasets to make short-term forecasts, test their consistency, and rank the model variants. Our results suggest that such a smoothed seismicity model is useful for forecasting induced seismicity within three days, and giving more weight to recent events improves forecast performance. Moreover, the location of the largest induced earthquake is forecast well by this model. Despite the good spatial performance, the model does not estimate the seismicity rate well: it frequently overestimates during stimulation and during the early post-stimulation period, and it systematically underestimates around shut-in. In this presentation, we also describe a robust estimate of information gain, a modification that can also benefit forecast experiments involving tectonic earthquakes.

  18. Updated Colombian Seismic Hazard Map

    Science.gov (United States)

    Eraso, J.; Arcila, M.; Romero, J.; Dimate, C.; Bermúdez, M. L.; Alvarado, C.

    2013-05-01

    The Colombian seismic hazard map used by the National Building Code (NSR-98) in effect until 2009 was developed in 1996. Since then, the National Seismological Network of Colombia has improved in both coverage and technology providing fifteen years of additional seismic records. These improvements have allowed a better understanding of the regional geology and tectonics which in addition to the seismic activity in Colombia with destructive effects has motivated the interest and the need to develop a new seismic hazard assessment in this country. Taking advantage of new instrumental information sources such as new broad band stations of the National Seismological Network, new historical seismicity data, standardized global databases availability, and in general, of advances in models and techniques, a new Colombian seismic hazard map was developed. A PSHA model was applied. The use of the PSHA model is because it incorporates the effects of all seismic sources that may affect a particular site solving the uncertainties caused by the parameters and assumptions defined in this kind of studies. First, the seismic sources geometry and a complete and homogeneous seismic catalog were defined; the parameters of seismic rate of each one of the seismic sources occurrence were calculated establishing a national seismotectonic model. Several of attenuation-distance relationships were selected depending on the type of seismicity considered. The seismic hazard was estimated using the CRISIS2007 software created by the Engineering Institute of the Universidad Nacional Autónoma de México -UNAM (National Autonomous University of Mexico). A uniformly spaced grid each 0.1° was used to calculate the peak ground acceleration (PGA) and response spectral values at 0.1, 0.2, 0.3, 0.5, 0.75, 1, 1.5, 2, 2.5 and 3.0 seconds with return periods of 75, 225, 475, 975 and 2475 years. For each site, a uniform hazard spectrum and exceedance rate curves were calculated. With the results, it is

  19. Seismic hazard assessment: Issues and alternatives

    Science.gov (United States)

    Wang, Z.

    2011-01-01

    Seismic hazard and risk are two very important concepts in engineering design and other policy considerations. Although seismic hazard and risk have often been used inter-changeably, they are fundamentally different. Furthermore, seismic risk is more important in engineering design and other policy considerations. Seismic hazard assessment is an effort by earth scientists to quantify seismic hazard and its associated uncertainty in time and space and to provide seismic hazard estimates for seismic risk assessment and other applications. Although seismic hazard assessment is more a scientific issue, it deserves special attention because of its significant implication to society. Two approaches, probabilistic seismic hazard analysis (PSHA) and deterministic seismic hazard analysis (DSHA), are commonly used for seismic hazard assessment. Although PSHA has been pro-claimed as the best approach for seismic hazard assessment, it is scientifically flawed (i.e., the physics and mathematics that PSHA is based on are not valid). Use of PSHA could lead to either unsafe or overly conservative engineering design or public policy, each of which has dire consequences to society. On the other hand, DSHA is a viable approach for seismic hazard assessment even though it has been labeled as unreliable. The biggest drawback of DSHA is that the temporal characteristics (i.e., earthquake frequency of occurrence and the associated uncertainty) are often neglected. An alternative, seismic hazard analysis (SHA), utilizes earthquake science and statistics directly and provides a seismic hazard estimate that can be readily used for seismic risk assessment and other applications. ?? 2010 Springer Basel AG.

  20. Seismic Hazard Analysis and Uniform Hazard Spectra for Different Regions of Kerman

    Directory of Open Access Journals (Sweden)

    Gholamreza Ghodrati Amiri

    2015-09-01

    Full Text Available This paper was present a seismic hazard analysis and uniform hazard spectra for different regions of Kerman city. A collected catalogue containing both historical and instrumental events and covering the period from 8th century AD until now within the area of 200 Km in radius were used and Seismic sources are modeled. Kijko method has been applied for estimating the seismic parameters considering lack of suitable seismic data, inaccuracy of the available information and uncertainty of magnitude in different periods. To determine the peak ground acceleration the calculations were performed by using the logic tree method. Two weighted attenuation relations were used; including Ghodrati et al, 0.6 and Zare et al, 0.4. Analysis was conducted for 13×8 grid points over Kerman region and adjacent areas with SEISRISK III software and in order to determine the seismic spectra Ghodrati et al, spectral attenuation relationships was used.

  1. 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

  2. First breath of the French seismic crisis committee with the 2009 L’Aquila earthquake

    Science.gov (United States)

    Voisin, C.; Delouis, B.; Vergnolle, M. M.; Klinger, Y.; Chiaraluce, L.; Margheriti, L.; Mariscal, A.; Péquégnat, C.; Schlagenhauf, A.; Traversa, P.

    2009-12-01

    The April 2009 L’Aquila earthquake launched the French seismic crisis committee. The mission of this committee is to gather all possible information about the earthquake and the available means for intervention (in terms of human potential and field instruments). These information are passed to the French INSU who decides of and raise fundings for a possible field experiment. The L’Aquila earthquake is the first event to be considered by the committee. French INSU was able to propose to the Italian INGV a set of 4 people and 20 seismic recorders in less than 30h. All stations were deployed over a broad area surrounding the event, in intelligence with the Italian team in 2,5 days. The seismic recorders are Taurus units associated to CMG40 sensors, belonging to SISMOB. They continuously recorded the ground movement, and more than 20,000 events. Data are freely distributed by the French national portal of seismic data Fosfore. They were mixed alltogether with the Italian data in order to perform the relocation of seismicity, and a first attempt to derive a 'noise' correlation tomography. This first attempt of an integrated post-seismic field study should provide the community with useful information in view of a future large event striking the European countries.

  3. Analysis of Seismic Swarms at the Oceanic Crust South of the Islas Marias, MEXICO

    Science.gov (United States)

    Tinoco Villa, M. E.; Nunez-Cornu, F. J.; Escudero, C. R.

    2013-12-01

    We analyzed data recorded at the Red Sismica Acelerometrica de Jalisco (RESAJ) from November 2010 to August 2013, focus on the seismicity occurred within an area south of the Islas Marias (-105.7, 20.3; -107, 21.8) west of Bahia de Banderas. We observed seismic swarms and low magnitude. Within our data set we identified four seismic swarms episodes. September 14 to 15, 2010 that starts with an earthquake of M = 5.6 at 23:31 followed by approximately 27 events, also has six earthquakes whose magnitudes are between M = 4.0 and M = 5.6; November 11 to December 5, 2011 which contains more than 25 events; October 12 to November 17, 2012 with more than 35 events with an earthquake M = 4.7 occurred on October 29; and finally the swarm occurred between January 20 and February 14, 2013 with over 120 events and one of M = 4.7 occurred on January 22. The last seismic swarm also present activity along two additional areas, one toward the west and the other toward the east of active area previously identified. This seismic activity is associated with the northern edge of the Barra de Navidad Trench whose geometry is unknown. Tectonic structures associated with this seismicity can be tsunamigenic and could represent a danger to nearby populations.

  4. Seismic Characterization of the Jakarta Basin

    Science.gov (United States)

    Cipta, A.; Saygin, E.; Cummins, P. R.; Masturyono, M.; Rudyanto, A.; Irsyam, M.

    2015-12-01

    Jakarta, Indonesia, is home to more than 10 million people. Many of these people live in seismically non-resilient structures in an area that historical records suggest is prone to earthquake shaking. The city lies in a sedimentary basin composed of Quaternary alluvium that experiences rapid subsidence (26 cm/year) due to groundwater extraction. Forecasts of how much subsidence may occur in the future are dependent on the thickness of the basin. However, basin geometry and sediment thickness are poorly known. In term of seismic hazard, thick loose sediment can lead to high amplification of seismic waves, of the kind that led to widespread damage in Mexico city during the Michoacan Earthquake of 1985. In order to characterize basin structure, a temporary seismograph deployment was undertaken in Jakarta in Oct 2013- Jan 2014. A total of 96 seismic instrument were deployed throughout Jakarta were deployed throughout Jakarta at 3-5 km spacing. Ambient noise tomography was applied to obtain models of the subsurface velocity structure. Important key, low velocity anomalies at short period (<8s) correspond to the main sedimentary sub-basins thought to be present based on geological interpretations of shallow stratigraphy in the Jakarta Basin. The result shows that at a depth of 300 m, shear-wave velocity in the northern part (600 m/s) of the basin is lower than that in the southern part. The most prominent low velocity structure appears in the northwest of the basin, down to a depth of 800 m, with velocity as low as 1200 m/s. This very low velocity indicates the thickness of sediment and the variability of basin geometry. Waveform computation using SPECFEM2D shows that amplification due to basin geometry occurs at the basin edge and the thick sediment leads to amplification at the basin center. Computation also shows the longer shaking duration occurrs at the basin edge and center of the basin. The nest step will be validating the basin model using earthquake events

  5. A seismic probability map

    Directory of Open Access Journals (Sweden)

    J. M. MUNUERA

    1964-06-01

    Full Text Available The material included in former two papers (SB and EF
    which summs 3307 shocks corresponding to 2360 years, up to I960, was
    reduced to a 50 years period by means the weight obtained for each epoch.
    The weitliing factor is the ratio 50 and the amount of years for every epoch.
    The frequency has been referred over basis VII of the international
    seismic scale of intensity, for all cases in which the earthquakes are equal or
    greater than VI and up to IX. The sum of products: frequency and parameters
    previously exposed, is the probable frequency expected for the 50
    years period.
    On each active small square, we have made the corresponding computation
    and so we have drawn the Map No 1, in percentage. The epicenters with
    intensity since X to XI are plotted in the Map No 2, in order to present a
    complementary information.
    A table shows the return periods obtained for all data (VII to XI,
    and after checking them with other computed from the first up to last shock,
    a list includes the probable approximate return periods estimated for the area.
    The solution, we suggest, is an appropriated form to express the seismic
    contingent phenomenon and it improves the conventional maps showing
    the equal intensity curves corresponding to the maximal values of given side.

  6. Bringing moveable seismic arrays to the oceans

    Science.gov (United States)

    Nolet, G.; Ogé, A.; Hello, Y.; Sukhovich, A.; Simons, F. J.; Argentino, J.

    2011-12-01

    We have developed a floating underwater robot that can detect seismic P waves from earthquakes at large distances and transmit these data by the Iridium satellite network in Rudics mode. Such P ways are used to image heterogeneities inside the planet (much as X-rays in medical imaging). The robot is named MERMAID for `Mobile Earthquake Recording in Marine Areas by Independent Divers'. So far, our only means of obtaining seismic data from water-covered regions is to install seismometers on the ocean floor or mount moored hydrophones and recuperate them and their data every year, which is very expensive. `Floats' have traditionally been developed for oceanographers to measure temperature and salinity and to track ocean currents, but their use in seismology is new. Because the robots change position as they drift with deep ocean currents at a speed of one to several km per day, this provides a means to provide seismic data over large surface areas without the need for costly recuperation and redeployment. Test and early experiments were conducted in the Mediterraen Sea with two prototypes and have already shown the feasibility of recording waves from strong earthquakes such a surface-reflected PP wave at a distance of 119 , and a P wave at a distance of 85 degrees - the latter from a magnitude 7.4 earthquake at a distance of 85 degrees with a signal/noise ratio better than 50. The second phase of this project - currently in progress - consists of the integration of the instrumentation and the intelligent electronic board in commercially available vehicles, such as the Apex (TWR) and Provor (NKE) floats, in order to detect and recognize P waves from teleseismic events. A buffer memory is used to store up to 10 events during continuous monitoring while the float drifts at a predetermined depth, typically between 1 and 2 km, if possible below the noisy SOFAR channel. The float surfaces for geolocation per GPS and Iridium signal transmission whenever a very strong P wave

  7. Numerical modeling of seismicity and geodynamics of the Kachchh rift zone, Gujarat, India

    Science.gov (United States)

    Vorobieva, Inessa; Mandal, Prantik; Gorshkov, Alexander

    2014-11-01

    The numerical block-and-fault model of lithosphere dynamics and seismicity (BAFD) is used to understand crustal motion and features of the observed seismicity in the Kachchh rift zone, Gujarat, Western India. The block-model allows simulating seismicity and geodynamics simultaneously unlike other modeling approaches for studying seismicity or geodynamics. The model structure of Kachchh rift zone is composed of seven major crustal blocks separated by fault planes. Based on the orientation of boundary crustal block movements, we develop a set of numerical experiments to analyze the spatial distribution of earthquakes, frequency-to-magnitude relationships, earthquake focal mechanisms, velocity field, and fault slip rates in the model. The main results of our modeling suggest that an NNW-SSE trending compression is a principal driving force in the Kachchh rift zone that explains basic features of the regional seismicity, direction of block motions, and the presence of an extensional stress regime associated with the Cambay rift zone. Large synthetic events occur on the fault segments associated with the Allah-Bund fault, Katrol hill fault and north Wagad fault which have been causative faults for the 1819 Mw7.7 Allah-Bund, 1956 Mw6.0 Anjar and 2001 Mw7.7 Bhuj earthquakes. The frequency-magnitude distribution for both synthetic seismicity and observed seismicity shows a similar slope. The focal mechanisms of the synthetic events are found to be consistent with those of earthquakes in the region. A special attention has been paid to study long-term and post-seismic deformations. Our results are in a qualitative agreement with the GPS post-seismic observations in the Kachchh rift zone. We infer that the observed seismicity and crustal block motions are a consequence of the dynamics of the entire regional fault and block system rather than that of a single causative fault only.

  8. Calculations on seismic coupling of underground explosions in salt

    Energy Technology Data Exchange (ETDEWEB)

    Heusinkveld, M.E.

    1981-01-20

    This report details the results of a theoretical study of seismic coupling and decoupling of underground explosions in a salt medium. A series of chemical and nuclear explosions was carried out years ago in salt domes for the Cowboy and the Dribble programs to provide experimental data on seismic coupling for both tamped explosions and explosions in cavities. The Cowboy program consisted of a series of chemical explosions, and the Dribble program consisted of the tamped nuclear Salmon event, the Sterling nuclear event in the Salmon cavity, and an associated site calibration effort. This report presents the results of extensive computer calculations, which are in satisfactory agreement with the experimental data. The calculations were extended to give general results on seismic coupling in salt. The measure of seismic coupling for most of this work was the residual reduced displacement potential (residual RDP). The decoupling associated with a shot in a cavity was expressed as the ratio of the resulting residual RDP to that of an equal-sized tamped shot.

  9. Mass Wasting In Planetary Environments: Implications For Seismicity

    Science.gov (United States)

    Weber, R. C.; Nahm, A. L.; Schmerr, N.

    2015-01-01

    On Earth, mass wasting events such as rock falls and landslides are well known conse-quences of seismic activity. Through a variety of re-mote sensing techniques, tectonic faults have been pos-itively identified on all four of the inner planets, Earth's Moon, several outer planet satellites, and aster-oids. High-resolution imaging has furthermore ena-bled positive identification of mass wasting events on many of these bodies. On Mars, it has been suggested that fallen boulders may be indicative of pale-omarsquakes. On the Moon, meteor impacts and moonquakes have likewise been suggested as potential triggering mechanisms for mass wasting. Indeed, we know from the Apollo era that the Moon experienc-es a wide variety of seismicity. Seismicity estimates play an important role in creat-ing regional geological characterizations, which are useful not only for understanding a planet's formation and evolution, but also of key importance to site selec-tion for landed missions. Here we investigate the re-gional effects of seismicity in planetary environments with the goal of determining whether surface features such as landslides and boulder trails on the Moon, Mars, and Mercury could be triggered by fault motion. We attempt to quantify the amount of near-source ground shaking necessary to mobilize the mate-rial observed in various instances of mass wasting.

  10. Robust satellite techniques for remote sensing of seismically active areas

    Directory of Open Access Journals (Sweden)

    S. Piscitelli

    2001-06-01

    Full Text Available Several satellite techniques have been recently proposed to remotely map seismically active zones and to monitor geophysical phenomena possibly associated with earthquakes. Even if questionable in terms of their effective applicability, all these techniques highlight as the major problem, still to be overcome, the high number of natural factors (independent of any seismic activity whose variable contributions to the investigated signal can be so high as to completely mask (or simulate the space-time anomaly possibly associated to the seismic event under study. A robust approach (RAT has recently been proposed (and successfully applied in the field of the monitoring of the major environmental risks which, better than other methods, seems suitable for recognising space-time anomalies in the satellite observational field also in the presence of highly variable contributions from atmospheric (transmittance, surface (emissivity and morphology and observational (time/season, but also solar and satellite zenithal angles conditions.This work presents the first preliminary results, based on several years of NOAA/AVHRR observations, regarding its extension to satellite monitoring of thermal anomalies possibly associated to seismically active areas of Southern Italy. The main merits of this approach are its robustness against the possibility of false events detection (specially important for this kind of applications as well as its intrinsic exportability not only to different geographic areas but also to different satellite instrumental packages.

  11. A preliminary seismic study of Taal Volcano, Luzon Island Philippines

    Science.gov (United States)

    You, S.-H.; Gung, Y.; Lin, C.-H.; Konstantinou, K. I.; Chang, T.-M.; Chang, E. T. Y.; Solidum, R.

    2013-03-01

    The very active Taal Volcano lies in the southern part of Luzon Island only 60 km from Manila, the capital of the Philippines. In March 2008 we deployed a temporary seismic network around Taal that consisted of 8 three-component short period seismometers. This network recorded during the period from March to November 2008 about 1050 local events. In the early data processing stages, unexpected linear drifting of clock time was clearly identified for a number of stations. The drifting rates of each problematic station were determined and the errors were corrected before further processing. Initial location of each event was derived by manually picked P-/S-phases arrival times using HYPO71 and a general velocity model based on AK135. Since the velocity structure beneath Taal is essentially unknown, we used travel times of 338 well-located events in order to derive a minimum 1D velocity model using VELEST. The resulting locations show that most events occurred at the shallow depth beneath the Taal Volcano, and two major earthquake groups were noticed, with one lying underneath the western shore of Taal lake and the other one spread around the eastern flank of the Taal Volcano. Since there is no reported volcano activities during the operation period of our seismic array, we are still not confident to interpret these findings in terms of other natures of volcano at the current stage. However, our work represents an important pioneer step towards other more advanced seismic studies in Taal Volcano.

  12. Seismic waveform analyses for the 1938 Off Fukushima earthquake sequence

    Science.gov (United States)

    Murotani, S.; Satake, K.

    2016-12-01

    The 1938 Off Fukushima (Shioya-oki) earthquakes sequence, which consists of five earthquakes of Mjmaranging from 6.9 to 7.5, occurred in the southern part of the 2011 Tohoku earthquake source area. In this region, the 1938 sequence was the only known M 7 earthquakes until the 2011 Tohoku earthquake occurred. Abe (1977, Tectonophysics) estimated the focal mechanisms and seismic moments of these events. The source parameters of the earthquake sequence are shown in the following table. However, the slip distributions are not known. Murotani et al. (2004, SSJ Fall Meeting) estimated slip distributions for event 1 (Mw 7.6, Fault size 60 km x 70 km), event 2 (Mw 7.9, Fault size 80 km x 60 km), and event 3 (Mw 7.8, Fault size 90 km x 60 km) from inversion of near-field seismic waveforms at Sendai, Niigata, Maebashi, Mito, and Hongo (Tokyo). We compared the observed teleseismic waveforms at Christchurch (CHR), De Bilt (DBN), Pasadena (PAS), and Pulkovo (PUL) with the calculated waveforms from these slip distributions. The result showed that the computed waveforms fairly reproduced the phases of the observation but the amplitudes for all events were several to several tens of times larger than the observations. It means that the slip amount and Mwobtained from the near field seismic waveforms inversion were over-estimated. For event 3, the slip distribution estimated from near-field data has two large slip areas (asperities) to the north and south of the hypocenter, although only the southern asperity was able to reproduce the observed near-field seismic waveforms. When we calculate the teleseismic waveforms using one asperity model, the amplitudes become small and the phases are reproduced better compared to two asperities model. Event 3 therefore seemed to have only one asperity. In addition to the re-analysis of near field seismic data, tsunami waveforms will be also computed and compared with the observations. This study was supported by JSPS KAKENHI Grant Number JP16H

  13. Body and Surface Wave Modeling of Observed Seismic Events

    Science.gov (United States)

    1980-09-01

    period WSS (30,90) instrument at Golden, Colorado. Figure 2. Three component observation of the San Fernando earthquake recorded at ALQ, Nev Mexico ...Planet. tat., 13, 85-96. . . . . . -, .. _ . 101 Console, R. (1976). ?%ccanismo focal* del terremoto del Friuli del 6 Maggio 1976, Ann. di Geof., 9

  14. An Adaptable Seismic Data Format

    Science.gov (United States)

    Krischer, Lion; Smith, James; Lei, Wenjie; Lefebvre, Matthieu; Ruan, Youyi; de Andrade, Elliott Sales; Podhorszki, Norbert; Bozdağ, Ebru; Tromp, Jeroen

    2016-11-01

    We present ASDF, the Adaptable Seismic Data Format, a modern and practical data format for all branches of seismology and beyond. The growing volume of freely available data coupled with ever expanding computational power opens avenues to tackle larger and more complex problems. Current bottlenecks include inefficient resource usage and insufficient data organization. Properly scaling a problem requires the resolution of both these challenges, and existing data formats are no longer up to the task. ASDF stores any number of synthetic, processed or unaltered waveforms in a single file. A key improvement compared to existing formats is the inclusion of comprehensive meta information, such as event or station information, in the same file. Additionally, it is also usable for any non-waveform data, for example, cross-correlations, adjoint sources or receiver functions. Last but not least, full provenance information can be stored alongside each item of data, thereby enhancing reproducibility and accountability. Any data set in our proposed format is self-describing and can be readily exchanged with others, facilitating collaboration. The utilization of the HDF5 container format grants efficient and parallel I/O operations, integrated compression algorithms and check sums to guard against data corruption. To not reinvent the wheel and to build upon past developments, we use existing standards like QuakeML, StationXML, W3C PROV and HDF5 wherever feasible. Usability and tool support are crucial for any new format to gain acceptance. We developed mature C/Fortran and Python based APIs coupling ASDF to the widely used SPECFEM3D_GLOBE and ObsPy toolkits.

  15. Very broadband seismic background noise analysis of permanent good vaulted seismic stations

    Science.gov (United States)

    Abd el-aal, Abd el-aziz Khairy

    2013-04-01

    This paper describes the results of a preliminary study conducted to analyze seismic background noise at sites of recently deployed very broadband stations of the Egyptian National Seismological Network (ENSN). The main purpose of the study is to assess the effects of permanent seismic vault construction and also to establish characteristics and origin of seismic noise at those sites. Another goal of this study is to determine the time needed for noise at those sites to stabilize. The power spectral densities of background noise at short period band (SP), very broadband (VBB), and ultra long period band (ULP) for each component of each broadband seismometer deployed in the different investigated sites are calculated. A MATLAB code has been developed that manages data processing and data analysis and compares the results with the high-noise model (NHNM) and low-noise model (NLNM) of Peterson (1993). Based on the obtained analysis, the noise stability and the efficiency of each station to record regional and teleseismic events are measured. The results of this study could be used in the future to evaluate station quality, to improve those processes that require background noise values, such as automatic association, and to improve the estimation of station and network detection and location thresholds.

  16. Statistical Studies of Induced and Triggered Seismicity at The Geysers, California

    Science.gov (United States)

    Hawkins, A.; Turcotte, D. L.; Yıkılmaz, M. B.; Kellogg, L. H.; Rundle, J. B.

    2017-06-01

    This study considers the statistics of fluid-induced and remotely triggered seismicity at The Geysers geothermal field, California. Little seismicity was reported before steam extraction began in 1960. Beginning in 1980 the residual water associated with power generation was re-injected, producing induced seismicity. Beginning in 1997 large-scale injections of cold water began to enhance the generation of steam. This led to an increase in M 1.25 events. The GR and decay statistics are given. However, to separate aftershocks from remotely triggered earthquakes, an additional triggered sequence is studied. The M = 7.2 4/4/10 Baja earthquake triggered some 34 M > 1.25 earthquakes at The Geysers in the first hour including an M = 3.37 event. We conclude that the remotely triggered seismicity is dominated by local aftershocks of the larger remotely triggered earthquakes.

  17. Event Modeling

    DEFF Research Database (Denmark)

    Bækgaard, Lars

    2001-01-01

    are dynamic and we present a modeling approach that can be used to model such dynamics. We characterize events as both information objects and change agents (Bækgaard 1997). When viewed as information objects events are phenomena that can be observed and described. For example, borrow events in a library can......The purpose of this chapter is to discuss conceptual event modeling within a context of information modeling. Traditionally, information modeling has been concerned with the modeling of a universe of discourse in terms of information structures. However, most interesting universes of discourse...... be characterized by their occurrence times and the participating books and borrowers. When we characterize events as information objects we focus on concepts like information structures. When viewed as change agents events are phenomena that trigger change. For example, when borrow event occurs books are moved...

  18. Evaluating the effectiveness of induced seismicity mitigation: Numerical modeling of wastewater injection near Greeley, Colorado

    Science.gov (United States)

    Brown, Megan R. M.; Ge, Shemin; Sheehan, Anne F.; Nakai, Jenny S.

    2017-08-01

    Mitigation of injection-induced seismicity in Greeley, Colorado, is based largely on proximity of wastewater disposal wells to seismicity and consists of cementation of the bottom of wells to eliminate connection between the disposal interval and crystalline basement. Brief injection rate reductions followed felt events, but injection rates returned to high levels, >250,000 barrels/month, within 6 months. While brief rate reduction reduces seismicity in the short term, overall seismicity is not reduced. We examine contributions to pore pressure change by injection from 22 wells within 30 km of the center of seismicity. The combined injection rate of seven disposal wells within 15 km of the seismicity (Greeley Wells) is correlated with the seismicity rate. We find that injection from NGL-C4A, the well previously suspected as the likely cause of the induced seismicity, is responsible for 28% of pore pressure increase. The other six Greeley Wells contribute 28% of pore pressure increase, and the 15 Far-field Wells between 15 and 30 km from the seismicity contribute 44% of pore pressure increase. Modeling results show that NGL-C4A plays the largest role in increased pore pressure but shows that the six other Greeley Wells have approximately the same influence as NGL-C4A. Furthermore, the 15 Far-field Wells have significant influence on pore pressure near the seismicity. Since the main mitigation action of cementing the bottom of wells has not decreased seismicity, mitigation based on reduced injection rates and spacing wells farther apart would likely have a higher potential for success.

  19. 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.

  20. Static behaviour of induced seismicity

    CERN Document Server

    Mignan, Arnaud

    2015-01-01

    The standard paradigm to describe seismicity induced by fluid injection is to apply nonlinear diffusion dynamics in a poroelastic medium. I show that the spatiotemporal behaviour and rate evolution of induced seismicity can, instead, be expressed by geometric operations on a static stress field produced by volume change at depth. I obtain laws similar in form to the ones derived from poroelasticity while requiring a lower description length. Although fluid flow is known to occur in the ground, it is not pertinent to the behaviour of induced seismicity. The proposed model is equivalent to the static stress model for tectonic foreshocks generated by the Non- Critical Precursory Accelerating Seismicity Theory. This study hence verifies the explanatory power of this theory outside of its original scope.

  1. Worldwide Marine Seismic Reflection Profiles

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC maintains a large volume of both Analog and Digital seismic reflection data. Currently only a limited number of lines are available online. Digital data include...

  2. Relocation and seismotectonic interpretation of the 2015 Ossa de Montiel (Albacete, Spain) seismic series.

    Science.gov (United States)

    Cantavella, Juan V.; Gaite, Beatriz; Ruiz, Mario; Romero, Paula; Gómez-García, Clara; Cerdeño, Roberto; Villaseñor, Antonio; Díaz, Jordi; Lozano, Lucía

    2016-04-01

    A moderate earthquake with magnitude Mw 4.7 occurred on February 23, 2015 to the NE of Ossa de Montiel (SE central Spain), in a region with very low seismic activity and poorly monitored by permanent seismic stations. Two days after the event a dense temporary seismic network consisting of 13 stations was deployed in this area until April 6, 2015, allowing to detect more than 500 events inside the network limits. The data gathered from this network along with the data from more distant seismic stations has allowed us to perform a precise hypocentral location of the Ossa de Montiel seismic series. For this location we have manually read the arrival times for all the stations and used relative location techniques based on waveform cross-correlations and a double-difference algorithm. In addition, we have studied the focal mechanism of the main shock and the largest aftershocks using first motion polarities and full waveform inversion. We have found that the mechanism and aftershock distribution is consistent with a NW-SE normal fault with a dip of 40 degrees to the NE at a depth of about 12 km. With these results we analyze the temporal evolution of the seismic sequence and propose a seismotectonic interpretation of a series developed in an area with scarce seismic information to this date.

  3. Seismic detections of the 15 February 2013 Chelyabinsk meteor from the dense ChinArray

    Science.gov (United States)

    Li, Lu; Wang, Baoshan; Peng, Zhigang; Wang, Weitao

    2016-08-01

    ChinArray is a dense portable broadband seismic network to cover the entire continental China, and the Phase I is deployed along the north-south seismic belt in southwest China. In this study, we analyze seismic data recorded on the ChinArray following the February 15, 2013 Chelyabinsk (Russia) meteor. This was the largest known object entering the Earth's atmosphere since the 1908 Tunguska meteor. The seismic energy radiated from this event was recorded by seismic stations worldwide including the dense ChinArray that are more than 4000 km away. The weak signal from the meteor event was contaminated by a magnitude 5.8 Tonga earthquake occurred ~20 min earlier. To test the feasibility of detecting the weak seismic signals from the meteor event, we compute vespagram and perform F-K analysis to the surface-wave data. We identify a seismic phase with back azimuth (BAZ) of 329.7° and slowness of 34.73 s/deg, corresponding to the surface wave from the Russian meteor event (BAZ ~325.97°). The surface magnitude ( M S) of the meteor event is 3.94 ± 0.18. We also perform similar analysis on the data from the broadband array F-net in Japan, and find the BAZ of the surface waves to be 316.61°. With the different BAZs of ChinArray and F-net, we locate the Russian meteor event at 58.80°N, 58.72°E. The relatively large mislocation (~438 km as compared with 55.15°N, 61.41°E by others) may be a result of the bending propagation path of surface waves, which deviates from the great circle path. Our results suggest that the dense ChinArray and its subarrays could be used to detect weak signals at teleseismic distances.

  4. Probabilistic Seismic Hazard Analysis of Injection-Induced Seismicity Utilizing Physics-Based Simulation

    Science.gov (United States)

    Johnson, S.; Foxall, W.; Savy, J. B.; Hutchings, L. J.

    2012-12-01

    Risk associated with induced seismicity is a significant factor in the design, permitting and operation of enhanced geothermal, geological CO2 sequestration, wastewater disposal, and other fluid injection projects. The conventional probabilistic seismic hazard analysis (PSHA) approach provides a framework for estimation of induced seismicity hazard but requires adaptation to address the particular occurrence characteristics of induced earthquakes and to estimation of the ground motions they generate. The assumption often made in conventional PSHA of Poissonian earthquake occurrence in both space and time is clearly violated by seismicity induced by an evolving pore pressure field. Our project focuses on analyzing hazard at the pre-injection design and permitting stage, before an induced earthquake catalog can be recorded. In order to accommodate the commensurate lack of pre-existing data, we have adopted a numerical physics-based approach to synthesizing and estimating earthquake frequency-magnitude distributions. Induced earthquake sequences are generated using the program RSQSIM (Dieterich and Richards-Dinger, PAGEOPH, 2010) augmented to simulate pressure-induced shear failure on faults and fractures embedded in a 3D geological structure under steady-state tectonic shear loading. The model uses available site-specific data on rock properties and in-situ stress, and generic values of frictional properties appropriate to the shallow reservoir depths at which induced events usually occur. The space- and time-evolving pore pressure field is coupled into the simulation from a multi-phase flow model. In addition to potentially damaging ground motions, induced seismicity poses a risk of perceived nuisance in nearby communities caused by relatively frequent, low magnitude earthquakes. Including these shallow local earthquakes in the hazard analysis requires extending the magnitude range considered to as low as M2 and the frequency band to include the short

  5. Earthquake detection capability of the Swiss Seismic Network

    Science.gov (United States)

    Nanjo, K. Z.; Schorlemmer, D.; Woessner, J.; Wiemer, S.; Giardini, D.

    2010-06-01

    A reliable estimate of completeness magnitudes is vital for many seismicity- and hazard-related studies. Here we adopted and further developed the Probability-based Magnitude of Completeness (PMC) method. This method determines network detection completeness (MP) using only empirical data: earthquake catalogue, phase picks and station information. To evaluate the applicability to low- or moderate-seismicity regions, we performed a case study in Switzerland. The Swiss Seismic Network (SSN) at present is recording seismicity with one of the densest networks of broad-band sensors in Europe. Based on data from 1983 January 1 to 2008 March 31, we found strong spatio-temporal variability of network completeness: the highest value of MP in Switzerland at present is 2.5 in the far southwest, close to the national boundary, whereas MP is lower than 1.6 in high-seismicity areas. Thus, events of magnitude 2.5 can be detected in all of Switzerland. We evaluated the temporal evolution of MP for the last 20 yr, showing the successful improvement of the SSN. We next introduced the calculation of uncertainties to the probabilistic method using a bootstrap approach. The results show that the uncertainties in completeness magnitudes are generally less than 0.1 magnitude units, implying that the method generates stable estimates of completeness magnitudes. We explored the possible use of PMC: (1) as a tool to estimate the number of missing earthquakes in moderate-seismicity regions and (2) as a network planning tool with simulation computations of installations of one or more virtual stations to assess the completeness and identify appropriate locations for new station installations. We compared our results with an existing study of the completeness based on detecting the point of deviation from a power law in the earthquake-size distribution. In general, the new approach provides higher estimates of the completeness magnitude than the traditional one. We associate this observation

  6. Proceedings of the Fourteenth Annual PL/DARPA Seismic Research Symposium

    Science.gov (United States)

    Lewkowicz, James F.; McPhetres, Jeanne M.

    1992-08-01

    Partial contents of papers presented include: A Generalized Likelihood Ratio Test in Outlier Detection or Script Matching; Analysis of Regional Bodywave Phases from Earthquakes in West China; Numerical Models of Quarry Blast Sources; Regional Seismic Event Discriminants -- What Works, What Doesn't and Why; Seismic Discrimination of Rockbursts in Mines; Deep Seismic Soundings in Northern Eurasia -- Interpretation of the Murmansk-Kizil Ultra-Long-Range Profile; Non-Linear Attenuation in the Near Source Region -- Characterization of Hysteresis in the Deformationof Rock Joints; Epicentral Azimuth Determination by Mini Array Processing; Source Function Deconvolution of Delay-Fired Explosions and Earthquakes at Regional Distances; Regional Wave Attenuation in Eurasia; Effects of an Irregular Free Surface and Moho on Regional Wave Propagation; Global Seismic Evidence Combination; Generalized Ray/Born Synthesis of Complete Regional Seismograms in Three-Dimensional Crustal Models; An X-Windows Graphics Tool to Compute Synthetic Seismograms for 2-D Models Using Gaussian Beams; Seismic Array Study of the Baikal Rift Zone, Siberia; Numerical Simulation of Nonlinear Attenuation Using an Endochronic Formulation; Applications of Array Spectral Factorization Methods to Regional Seismic Discrimination and Three-Component Processing; A Network-Accessible Geological and Geophysical Database for Eurasia; Multivariate Seismic Calibration for the Novaya Zemlya Test Site;and Ground-Truth Data for Seismic Discrimination Research.

  7. From seismic network optimization to real-time diagnosis of magma migration

    Science.gov (United States)

    Taisne, B.; Aoki, Y.

    2013-12-01

    Triggering mechanism of a seismic swarm has to be identified with great confidence in real time. Crisis response will not be the same whether magma is involved or not. The method based on the Seismic Amplitude Ratio Analysis enables a rapid and unambiguous diagnosis to detect migrating micro-seismicity. Combined with other measurements, this migrating seismicity could be linked to complex motions of magma within the volcanic edifice. The beauty of this method lies in the fact that the ratio of seismic energy recorded at different stations is independent of the seismic energy radiated at the source. Drastic changes in attenuation are unlikely to occur at the time scale of magma intrusion, therefore temporal evolutions in the measured ratio have to be explained by a change in the source location. Based on a simple assumption this technique can be used to assess the potential of existing monitoring seismic network to detect migrating events in real-time. It can also be used to design monitoring seismic network based on the available number of sensors as well as from field constraints. Network capability also depends on the noise level at each station, therefore this noise is used to define the magnitude threshold that can be detected as a function of the distance.

  8. Cetacean behavioral responses to noise exposure generated by seismic surveys: how to mitigate better?

    Directory of Open Access Journals (Sweden)

    Clara Monaco

    2016-09-01

    Full Text Available Cetaceans use sound in many contexts, such as in social interactions, as well as to forage and to react in dangerous situations. Little information exists to describe how they respond physically and behaviorally to intense and long-term noise levels. Effects on cetaceans from seismic survey activities need to be understood in order to determine detailed acoustic exposure guidelines and to apply appropriated mitigation measures. This study examines direct behavioral responses of cetaceans in the southern Mediterranean Sea during seismic surveys with large airgun arrays (volume up to 5200 ci used in the TOMO-ETNA active seismic experiment of summer 2014. Wide Angle Seismic and Multi-Channel Seismic surveys had carried out with refraction and reflection seismic methods, producing about 25,800 air-gun shots. Visual monitoring undertaken in the 26 daylights of seismic exploration adopted the protocol of the Joint Nature Conservation Committee. Data recorded were analyzed to examine effects on cetaceans. Sighting rates, distance and orientation from the airguns were compared for different volume categories of the airgun arrays. Results show that cetaceans can be disturbed by seismic survey activities, especially during particularly events. Here we propose many integrated actions to further mitigate this exposure and implications for management.

  9. Seismic reflection and refraction methods

    Digital Repository Service at National Institute of Oceanography (India)

    Chaubey, A.K.

    , reflection method is a very sophisticated version of the echosounding used in submarines, ships, and radar systems. Whereas, in seismic refraction method, principal portion of the wave-path is along the interface between the two layers and hence... into electrical signals, which are recorded digitally. The Ocean Bottom Seismometers 221 (OBS) are normally designed to record the earth motion under oceans and lakes from air-gun seismic sources. The air gun array is towed behind a ship usually at a...

  10. The Norwegian Seismic Array (NORSAR)

    Science.gov (United States)

    1982-07-01

    computed subcritical reflection travel times do not agree with the secondar’ arrivals between 70 km and 110 km. Now, applying the reflectivity method to...however, the relatively early PMp subcritical arrivals (Fig. VI.6.1) must be accounted for. These suggest a thinner crust as compared to the laterally...J. Orcutt and T.H. Jordan , 1982: The Marine Seismic System: signals and noise. DARPA Symposium on seismic detection, analysis, discrimination and

  11. Visualization of volumetric seismic data

    Science.gov (United States)

    Spickermann, Dela; Böttinger, Michael; Ashfaq Ahmed, Khawar; Gajewski, Dirk

    2015-04-01

    Mostly driven by demands of high quality subsurface imaging, highly specialized tools and methods have been developed to support the processing, visualization and interpretation of seismic data. 3D seismic data acquisition and 4D time-lapse seismic monitoring are well-established techniques in academia and industry, producing large amounts of data to be processed, visualized and interpreted. In this context, interactive 3D visualization methods proved to be valuable for the analysis of 3D seismic data cubes - especially for sedimentary environments with continuous horizons. In crystalline and hard rock environments, where hydraulic stimulation techniques may be applied to produce geothermal energy, interpretation of the seismic data is a more challenging problem. Instead of continuous reflection horizons, the imaging targets are often steep dipping faults, causing a lot of diffractions. Without further preprocessing these geological structures are often hidden behind the noise in the data. In this PICO presentation we will present a workflow consisting of data processing steps, which enhance the signal-to-noise ratio, followed by a visualization step based on the use the commercially available general purpose 3D visualization system Avizo. Specifically, we have used Avizo Earth, an extension to Avizo, which supports the import of seismic data in SEG-Y format and offers easy access to state-of-the-art 3D visualization methods at interactive frame rates, even for large seismic data cubes. In seismic interpretation using visualization, interactivity is a key requirement for understanding complex 3D structures. In order to enable an easy communication of the insights gained during the interactive visualization process, animations of the visualized data were created which support the spatial understanding of the data.

  12. Impact-induced seismic activity on asteroid 433 Eros: a surface modification process.

    Science.gov (United States)

    Richardson, James E; Melosh, H Jay; Greenberg, Richard

    2004-11-26

    High-resolution images of the surface of asteroid 433 Eros revealed evidence of downslope movement of a loose regolith layer, as well as the degradation and erasure of small impact craters (less than approximately 100 meters in diameter). One hypothesis to explain these observations is seismic reverberation after impact events. We used a combination of seismic and geomorphic modeling to analyze the response of regolith-covered topography, particularly craters, to impact-induced seismic shaking. Applying these results to a stochastic cratering model for the surface of Eros produced good agreement with the observed size-frequency distribution of craters, including the paucity of small craters.

  13. Contributions to the Chile’s Seismic History: the Case of the Great Earthquake of 1730

    Directory of Open Access Journals (Sweden)

    María X. Urbina Carrasco

    2016-12-01

    Full Text Available According to the new and previously known documents it is concluded the earthquake of Chile in 1730 was composed by two independent earthquakes, each associated to a tsunami. Considering the latitudinal extension of the damage and the size of the tsunamis, it can be taken as the largest seismic event occurred in the history of Metropolitan or Central Chile. These conclusions allow to know better the seismic sequence of Central Chile, the Seismic History of the country, and contribute to the knowledge of the colonial history of the kingdom of Chile.

  14. Long Term Seismic Observation in Mariana by OBSs : Double Seismic Zone and Upper Mantle Structure

    Science.gov (United States)

    Shiobara, H.; Sugioka, H.; Mochizuki, K.; Oki, S.; Kanazawa, T.; Fukao, Y.; Suyehiro, K.

    2005-12-01

    In order to obtain the deep arc structural image of Mariana, a large-scale seismic observation by using 58 long-term ocean bottom seismometers (LTOBS) had been performed from June 2003 until April 2004, which is a part of the MARGINS program funded by the NSF. Prior to this observation, a pilot long-term seismic array observation was conducted in the same area by using 10 LTOBSs from Oct. 2001 until Feb. 2003. At that time, 8 LTOBSs were recovered but one had no data. Recently, 2 LTOBSs, had troubles in the releasing, were recovered by the manned submersible (Shinkai 6500, Jamstec) for the research of the malfunction in July 2005. By using all 9 LTOBS's data, those are about 11 months long, hypocenter determination was performed and more than 3000 local events were found. Even with the 1D velocity structure based on the iasp91 model, double seismic zones and a systematic shift of epicenters between the PDE and this study were observed. To investigate the detail of hypocenter distribution and the 3D velocity structure, the DD inversion (tomoDD: Zhang and Thurber, 2003) was applied for this data set with the 1D structure initial model except for the crust, which has been surveyed by using a dense airgun-OBS system (Takahashi et al., 2003). The result of relocated hypocenters shows clear double seismic zones until about 200 km depth, a high activity area around the fore-arc serpentine sea-mount, the Big Blue, and a lined focuses along the current ridge axis in the back-arc basin, and the result of the tomography shows a image of subducting slab and a low-Vs region below the same sea-mount mentioned. The wedge mantle structure was not clearly resolved due to the inadequate source-receiver coverage, which will be done in the recent experiment.

  15. Monte Carlo Volcano Seismic Moment Tensors

    Science.gov (United States)

    Waite, G. P.; Brill, K. A.; Lanza, F.

    2015-12-01

    Inverse modeling of volcano seismic sources can provide insight into the geometry and dynamics of volcanic conduits. But given the logistical challenges of working on an active volcano, seismic networks are typically deficient in spatial and temporal coverage; this potentially leads to large errors in source models. In addition, uncertainties in the centroid location and moment-tensor components, including volumetric components, are difficult to constrain from the linear inversion results, which leads to a poor understanding of the model space. In this study, we employ a nonlinear inversion using a Monte Carlo scheme with the objective of defining robustly resolved elements of model space. The model space is randomized by centroid location and moment tensor eigenvectors. Point sources densely sample the summit area and moment tensors are constrained to a randomly chosen geometry within the inversion; Green's functions for the random moment tensors are all calculated from modeled single forces, making the nonlinear inversion computationally reasonable. We apply this method to very-long-period (VLP) seismic events that accompany minor eruptions at Fuego volcano, Guatemala. The library of single force Green's functions is computed with a 3D finite-difference modeling algorithm through a homogeneous velocity-density model that includes topography, for a 3D grid of nodes, spaced 40 m apart, within the summit region. The homogenous velocity and density model is justified by long wavelength of VLP data. The nonlinear inversion reveals well resolved model features and informs the interpretation through a better understanding of the possible models. This approach can also be used to evaluate possible station geometries in order to optimize networks prior to deployment.

  16. Retrieving impulse response function amplitudes from the ambient seismic field

    Science.gov (United States)

    Viens, Loïc; Denolle, Marine; Miyake, Hiroe; Sakai, Shin'ichi; Nakagawa, Shigeki

    2017-07-01

    of the anticausal part agree well with those of a shallow Mw 4.7 event that occurred close to the virtual source. This study demonstrates that the deconvolution technique seems to be the best strategy to retrieve reliable relative amplitudes from the ambient seismic field in the Kanto Basin.

  17. Hydra—The National Earthquake Information Center’s 24/7 seismic monitoring, analysis, catalog production, quality analysis, and special studies tool suite

    Science.gov (United States)

    Patton, John M.; Guy, Michelle R.; Benz, Harley M.; Buland, Raymond P.; Erickson, Brian K.; Kragness, David S.

    2016-08-18

    This report provides an overview of the capabilities and design of Hydra, the global seismic monitoring and analysis system used for earthquake response and catalog production at the U.S. Geological Survey National Earthquake Information Center (NEIC). Hydra supports the NEIC’s worldwide earthquake monitoring mission in areas such as seismic event detection, seismic data insertion and storage, seismic data processing and analysis, and seismic data output.The Hydra system automatically identifies seismic phase arrival times and detects the occurrence of earthquakes in near-real time. The system integrates and inserts parametric and waveform seismic data into discrete events in a database for analysis. Hydra computes seismic event parameters, including locations, multiple magnitudes, moment tensors, and depth estimates. Hydra supports the NEIC’s 24/7 analyst staff with a suite of seismic analysis graphical user interfaces.In addition to the NEIC’s monitoring needs, the system supports the processing of aftershock and temporary deployment data, and supports the NEIC’s quality assurance procedures. The Hydra system continues to be developed to expand its seismic analysis and monitoring capabilities.

  18. 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.

  19. Imaging spatial and temporal seismic source variations at Sierra Negra Volcano, Galapagos Islands using back-projection methods

    Science.gov (United States)

    Kelly, C. L.; Lawrence, J. F.; Ebinger, C. J.

    2013-12-01

    Imaging spatial and temporal seismic source variations at Sierra Negra Volcano, Galapagos Islands using back-projection methods Cyndi Kelly1, Jesse F. Lawrence1, Cindy Ebinger2 1Stanford University, Department of Geophysics, 397 Panama Mall, Stanford, CA 94305, USA 2University of Rochester, Department of Earth and Environmental Science, 227 Hutchison Hall, Rochester, NY 14627, USA Low-magnitude seismic signals generated by processes that characterize volcanic and hydrothermal systems and their plumbing networks are difficult to observe remotely. Seismic records from these systems tend to be extremely 'noisy', making it difficult to resolve 3D subsurface structures using traditional seismic methods. Easily identifiable high-amplitude bursts within the noise that might be suitable for use with traditional seismic methods (i.e. eruptions) tend to occur relatively infrequently compared to the length of an entire eruptive cycle. Furthermore, while these impulsive events might help constrain the dynamics of a particular eruption, they shed little insight into the mechanisms that occur throughout an entire eruption sequence. It has been shown, however, that the much more abundant low-amplitude seismic 'noise' in these records (i.e. volcanic or geyser 'tremor') actually represents a series of overlapping low-magnitude displacements that can be directly linked to magma, fluid, and volatile movement at depth. This 'noisy' data therefore likely contains valuable information about the processes occurring in the volcanic or hydrothermal system before, during and after eruption events. In this study, we present a new method to comprehensively study how the seismic source distribution of all events - including micro-events - evolves during different phases of the eruption sequence of Sierra Negra Volcano in the Galapagos Islands. We apply a back-projection search algorithm to image sources of seismic 'noise' at Sierra Negra Volcano during a proposed intrusion event. By analyzing

  20. SENTINEL EVENTS

    Directory of Open Access Journals (Sweden)

    Andrej Robida

    2004-09-01

    Full Text Available Background. The Objective of the article is a two year statistics on sentinel events in hospitals. Results of a survey on sentinel events and the attitude of hospital leaders and staff are also included. Some recommendations regarding patient safety and the handling of sentinel events are given.Methods. In March 2002 the Ministry of Health introduce a voluntary reporting system on sentinel events in Slovenian hospitals. Sentinel events were analyzed according to the place the event, its content, and root causes. To show results of the first year, a conference for hospital directors and medical directors was organized. A survey was conducted among the participants with the purpose of gathering information about their view on sentinel events. One hundred questionnaires were distributed.Results. Sentinel events. There were 14 reports of sentinel events in the first year and 7 in the second. In 4 cases reports were received only after written reminders were sent to the responsible persons, in one case no reports were obtained. There were 14 deaths, 5 of these were in-hospital suicides, 6 were due to an adverse event, 3 were unexplained. Events not leading to death were a suicide attempt, a wrong side surgery, a paraplegia after spinal anaesthesia, a fall with a femoral neck fracture, a damage of the spleen in the event of pleural space drainage, inadvertent embolization with absolute alcohol into a femoral artery and a physical attack on a physician by a patient. Analysis of root causes of sentinel events showed that in most cases processes were inadequate.Survey. One quarter of those surveyed did not know about the sentinel events reporting system. 16% were having actual problems when reporting events and 47% beleived that there was an attempt to blame individuals. Obstacles in reporting events openly were fear of consequences, moral shame, fear of public disclosure of names of participants in the event and exposure in mass media. The majority of

  1. Hydrologic modulation of seismicity in western China 1991-2014

    Science.gov (United States)

    Randolph-Flagg, Noah; Day, Jesse; Manga, Michael; Bürgmann, Roland

    2015-04-01

    Hydrologic loading, changes in pore fluid pressures, solid earth tides, and stresses due to thermoelastic expansion have all been proposed to modulate seismicity in a range of tectonic and climatic settings. Seismicity from 1991-2014 (24,892 events) in western China, between 20° and 60° N and between 105° and 70° E, appears to be seasonally modulated with 50% more shallow events in the spring and fall than the summer and winter. We show that this modulation is statistically significant using Schuster tests, analysis of variance tests, and the multifrequential periodogram approach on complete catalogs, a catalog of repeating earthquakes (Schaff and Richards, JGR, 2011), and declustered catalogs. Leveraging the tectonic and climatic heterogeneity in our study region, we compare each of the proposed causes of modulation to observations. We find that the spatial variation of modulation correlates best with spatial variation in hydrologic loading as measured by the GRACE satellites.

  2. The Propagation of Seismic Waves in the Presence of Strong Elastic Property Contrasts

    Science.gov (United States)

    Saleh, R.; Jeyaraj, R.; Milkereit, B.; Liu, Q.; Valley, B.

    2012-12-01

    In an active underground mine there are many seismic activities taking place, such as seismic noises, blasts, tremors and microseismic events. In between the activities, the microseismic events are mainly used for monitoring purposes. The frequency content of microseismic events can be up to few KHz, which can result in wavelengths on the order of a few meters in hard rock environment. In an underground mine, considering the presence of both small wavelength and strong elastic contrasts, the simulation of seismic wave propagation is a challenge. With the recent availability of detailed 3D rock property models of mines, in addition to the development of efficient numerical techniques (such as Spectral Element Method (SEM)), and parallel computation facilities, a solution for such a problem is achievable. Most seismic wave scattering studies focus on large scales (>1 km) and weak elastic contrasts (velocity perturbations less than 10%). However, scattering in the presence of small-scale heterogeneities and large elastic contrasts is an area of ongoing research. In a mine environment, the presence of strong contrast discontinuities such as massive ore bodies, tunnels and infrastructure lead to discontinuities of displacement and/or stress tensor components, and have significant impact on the propagation of seismic waves. In order to obtain an accurate image of wave propagation in such a complex media, it is necessary to consider the presence of these discontinuities in numerical models. In this study, the effects of such a contrast are illustrated with 2D/3D modeling and compared with real broadband 3-component seismic data. The real broadband 3-component seismic data will be obtained in one of the Canadian underground mines in Ontario. One of the possible scenarios investigated in this study that may explain the observed complexity in seismic wavefield pattern in hard rock environments is the effect of near field displacements rather than far field. Considering the

  3. Seismic history of the Altai-Sayan region and the 2011-2012 earthquakes in Tuva

    Directory of Open Access Journals (Sweden)

    Aleksandr N. Ovsyuchenko

    2017-03-01

    Full Text Available The Tuva earthquakes of 2011-2012, being the strongest in the history of seismic study in Tuva, attracted the attention of professionals and became the first well-studied seismic events in Tuva. The paper provides a general overview of seismic history of the Altai-Sayan region and a look at a particular seismogenic structure – the Kaakhem system of active faults, where the 2011-2012 earthquakes occurred. A reconstruction of the seismic history of Tuva can follow a number of paths – aside from paleoseismological methods, those of archeoseismology and historical seismology can be quite helpful. Legends and more specific information on ancient constructions’ collapse can provide some useful information on earthquake dates, as well as earth tremor mapping. To locate seismic foci of the earthquakes of the past and assess their parameters, we may recourse to dating their geological vestiges, written evidence and archaeoseismological study outcomes obtained by means of velocity destruction indicators set in ancient buildings. Our comparative analysis has shown that the events of 2011-2012 are "ordinary" events against the background of the most powerful seismic catastrophes of the 20th century in the Altai-Sayan region, as well as prehistoric palaeoearthquakes located in the Kaakhem fault zone.

  4. Reassessing the 2006 Guerrero slow-slip event, Mexico : Implications for large earthquakes in the Guerrero Gap

    NARCIS (Netherlands)

    Bekaert, D.P.S.; Hooper, A.; Wright, T.J.

    2015-01-01

    In Guerrero, Mexico, slow-slip events have been observed in a seismic gap, where no earthquakes have occurred since 1911. A rupture of the entire gap today could result in a Mw 8.2–8.4 earthquake. However, it remains unclear how slow-slip events change the stress field in the Guerrero seismic region

  5. Event Modeling

    DEFF Research Database (Denmark)

    Bækgaard, Lars

    2001-01-01

    The purpose of this chapter is to discuss conceptual event modeling within a context of information modeling. Traditionally, information modeling has been concerned with the modeling of a universe of discourse in terms of information structures. However, most interesting universes of discourse...... are dynamic and we present a modeling approach that can be used to model such dynamics.We characterize events as both information objects and change agents (Bækgaard 1997). When viewed as information objects events are phenomena that can be observed and described. For example, borrow events in a library can...

  6. Seismic Waveform Characterization at LLNL: Analyst Guidelines and Issues

    Energy Technology Data Exchange (ETDEWEB)

    Ryall, F; Schultz, C A

    2001-11-01

    In the first section of this paper we present an overview of general set of procedures that we have followed in seismic waveform analysis. In the second section we discuss a number of issues and complexities that we have encountered in analysis of events in the Middle East, North Africa, Europe, and parts of the European Arctic. To illustrate these complexities we can include examples of waveforms recorded over a variety of paths in these regions.

  7. Historical eartquakes at Ischia island and seismic hazard assessment

    OpenAIRE

    Carlino, S.; Cubellis, E.; Marturano, A.

    2006-01-01

    Hystorical data of seismicity at Ischia island (Southern Italy) cover a period of almost 800 years. Since 1228 numerous events exceeded VII MCS degree. The epicentral areas of the earthquakes are located in the northern sector of the island; only one earthquake (1302, VIII MCS degree) was correlated with the latter eruption occurred during 1301-02 AD along the eastern sector of the island. In few cases the earthquakes (1228, 1863, 1881, 1883 AD) were followed by landslides whic...

  8. Seismic array processing and computational infrastructure for improved monitoring of Alaskan and Aleutian seismicity and volcanoes

    Science.gov (United States)

    Lindquist, Kent Gordon

    We constructed a near-real-time system, called Iceworm, to automate seismic data collection, processing, storage, and distribution at the Alaska Earthquake Information Center (AEIC). Phase-picking, phase association, and interprocess communication components come from Earthworm (U.S. Geological Survey). A new generic, internal format for digital data supports unified handling of data from diverse sources. A new infrastructure for applying processing algorithms to near-real-time data streams supports automated information extraction from seismic wavefields. Integration of Datascope (U. of Colorado) provides relational database management of all automated measurements, parametric information for located hypocenters, and waveform data from Iceworm. Data from 1997 yield 329 earthquakes located by both Iceworm and the AEIC. Of these, 203 have location residuals under 22 km, sufficient for hazard response. Regionalized inversions for local magnitude in Alaska yield Msb{L} calibration curves (logAsb0) that differ from the Californian Richter magnitude. The new curve is 0.2\\ Msb{L} units more attenuative than the Californian curve at 400 km for earthquakes north of the Denali fault. South of the fault, and for a region north of Cook Inlet, the difference is 0.4\\ Msb{L}. A curve for deep events differs by 0.6\\ Msb{L} at 650 km. We expand geographic coverage of Alaskan regional seismic monitoring to the Aleutians, the Bering Sea, and the entire Arctic by initiating the processing of four short-period, Alaskan seismic arrays. To show the array stations' sensitivity, we detect and locate two microearthquakes that were missed by the AEIC. An empirical study of the location sensitivity of the arrays predicts improvements over the Alaskan regional network that are shown as map-view contour plots. We verify these predictions by detecting an Msb{L} 3.2 event near Unimak Island with one array. The detection and location of four representative earthquakes illustrates the expansion

  9. Emergency seismic and CGPS networks: a first employment for the L'Aquila Mw 6.3 earthquake

    Science.gov (United States)

    Abruzzese, L.; Avallone, A.; Cecere, G.; Cattaneo, M.; Cardinale, V.; Castagnozzi, A.; Cogliano, R.; Criscuoli, F.; D'Agostino, N.; D'Ambrosio, C.; de Luca, G.; D'Anastasio, E.; Falco, L.; Flammia, V.; Migliari, F.; Minichiello, F.; Memmolo, A.; Monachesi, G.; Moschillo, R.; Pignone, M.; Pucillo, S.; Selvaggi, G.; Zarrilli, L.; Delladio, A.; Govoni, A.; Franceschi, D.; de Martin, M.; Moretti, M.

    2009-12-01

    During the last 2 years, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) developed an important real-time temporary seismic network infrastructure in order to densify the Italian National Seismic Network in epicentral areas thus enhancing the localization of the micro-seismicity after main earthquake events. This real-time temporary seismic network is constituted by various mobile and autonomous seismic stations that in group of three are telemetered to a Very Small Aperture Terminal (VSAT). This system uses a dedicated bandwidth on UHF, Wi-Fi and satellite frequency that allows the data flow in real-time at INGV centre in Rome (and Grottaminarda as backup center). The deployment of the seismic network is managed in a geographical information systems (GIS) by particular scenarios that visualizes, for the epicentral area, information about instrumental seismicity, seismic risk, macroseismic felts and territorial data. Starting from digital terrain model, the surface spatial analysis (Viewshed, Observer Point) allows the geographic arrangement of the stations and relative scenarios. The April, 6th, 2009 Mw 6.3 L'Aquila destructive earthquake represented the first real-case to test the entire emergency seismic network infrastructure. Less than 6 hours after the earthquake occurrence, a first accelerometer station was already sending data at INGV seismic monitoring headquarters. A total number of 9 seismic stations have been installed within 3 days after the earthquake. Furthermore, 5 permanent GPS stations have been installed in the epicentral area within 1 to 9 days after the main shock to detect the post-seismic deformation induced by the earthquake. We will show and describe the details of the Emergency Seismic Network infrastructure, and the first results from the collected data.

  10. Seismic patterns of the Guerrero-Oaxaca, Mexico region, and its relationship to the continental margin structure

    Science.gov (United States)

    Yamamoto, Jaime; González-Moran, Tomas; Quintanar, Luis; Zavaleta, Ana B.; Zamora, Araceli; Espindola, Victor H.

    2013-01-01

    The main purpose of this paper is to enhance awareness on the seismic evidences that suggest a possible segmentation of the continental margin at the Guerrero-Oaxaca, Mexico region. Data from a recent 7 months survey of microseismicity carried out from 2008 December to 2009 June at Ometepec, Guerrero area, using a portable broad-band digital seismographs network added with data of a previous survey and the aftershocks distribution of the 1982 and 1995 major earthquakes permit to infer the characteristics of the seismic patterns of the Acapulco-Pinotepa Nacional portion of the southern Mexico subduction region. Two different seismic regimens are apparent, one in the Acapulco-Marquelia and the other in the Marquelia-Pinotepa Nacional areas. In the Acapulco-Marquelia portion, the seismicity is broader and dispersed starting at the coast up to 160 km inland approximately. Seismicity in the Marquelia-Pinotepa portion, on the other hand, is narrower and concentrates near the coast. The two seismic regimens are separated by a narrow band or strip of low seismic activity, nearly perpendicular to the coast and trench axis. The apparent low seismicity strip that separates the seismic regimens may trace the position either of a seismically inactive fracture zone or a seismic gap. Moreover, careful observation of the epicentres distribution of the Marquelia-Pinotepa segment reveals two clusters of events separated by another low seismicity strip. Thus, the two observed low activity strips, located near the northern tip of the Ometepec submarine canyon and Punta Maldonado, respectively, are interpreted in this paper as corresponding to disruptions of the continental margin. Other low seismic activity strips probably exist but these two are the most conspicuous. Supplementary information on fault mechanisms available for this area seems to substantiate additionally this interpretation. The observations reported are important to understand the mechanics of the major earthquakes

  11. Iceberg calving as a primary source of regional‐scale glacier‐generated seismicity in the St. Elias Mountains, Alaska

    Science.gov (United States)

    O'Neel, Shad; Larsen, Christopher F.; Rupert, Natalia; Hansen, Roger

    2010-01-01

    Since the installation of the Alaska Regional Seismic Network in the 1970s, data analysts have noted nontectonic seismic events thought to be related to glacier dynamics. While loose associations with the glaciers of the St. Elias Mountains have been made, no detailed study of the source locations has been undertaken. We performed a two-step investigation surrounding these events, beginning with manual locations that guided an automated detection and event sifting routine. Results from the manual investigation highlight characteristics of the seismic waveforms including single-peaked (narrowband) spectra, emergent onsets, lack of distinct phase arrivals, and a predominant cluster of locations near the calving termini of several neighboring tidewater glaciers. Through these locations, comparison with previous work, analyses of waveform characteristics, frequency-magnitude statistics and temporal patterns in seismicity, we suggest calving as a source for the seismicity. Statistical properties and time series analysis of the event catalog suggest a scale-invariant process that has no single or simple forcing. These results support the idea that calving is often a response to short-lived or localized stress perturbations. Our results demonstrate the utility of passive seismic instrumentation to monitor relative changes in the rate and magnitude of iceberg calving at tidewater glaciers that may be volatile or susceptible to ensuing rapid retreat, especially when existing seismic infrastructure can be used.

  12. The importance of earthquake interactions in forecasting injection induced seismicity: retrospective modelling of the Basel Enhanced Geothermal System

    Science.gov (United States)

    Catalli, Flaminia; Rinaldi, Antonio Pio; Gischig, Valentin; Wiemer, Stefan

    2016-04-01

    We explore the role of earthquake interactions during an injection induced seismic sequence. We propose a model, which considers both a transient pressure and the static stress redistribution due to event interactions as triggering mechanisms for induced seismicity. We produce more than one thousand of stochastic seismic catalogues that allow a probabilistic analysis of the problem. By calibrating the model against observations at the Enhanced Geothermal System (EGS) of Basel, Switzerland, we are able to reproduce the time behaviour of the seismicity rate. In particular, we observe that considering earthquake interactions in the modelling can lead to a larger number of expected seismic events (27% more) if compared to a pressure-induced seismicity only. The increase of the rate is true particularly after the end of the injection activity, in accordance with the simultaneous increase of the Coulomb Index (CI, i.e. the percentage of events that occur in locations with positive, cumulative Coulomb static stress changes). We conclude that implementing a model for estimating the static stress changes due to mutual event interactions increases significantly the understanding of the process. This implicitly allows for an improved methodology to forecast the behaviour of induced seismicity, therefore having a significant implication in hazard assessment.

  13. Seismic failure modes and seismic safety of Hardfill dam

    Directory of Open Access Journals (Sweden)

    Kun XIONG

    2013-04-01

    Full Text Available Based on microscopic damage theory and the finite element method, and using the Weibull distribution to characterize the random distribution of the mechanical properties of materials, the seismic response of a typical Hardfill dam was analyzed through numerical simulation during the earthquakes with intensities of 8 degrees and even greater. The seismic failure modes and failure mechanism of the dam were explored as well. Numerical results show that the Hardfill dam remains at a low stress level and undamaged or slightly damaged during an earthquake with an intensity of 8 degrees. During overload earthquakes, tensile cracks occur at the dam surfaces and extend to inside the dam body, and the upstream dam body experiences more serious damage than the downstream dam body. Therefore, under the seismic conditions, the failure pattern of the Hardfill dam is the tensile fracture of the upstream regions and the dam toe. Compared with traditional gravity dams, Hardfill dams have better seismic performance and greater seismic safety.

  14. Integrated seismic monitoring in Slovakia

    Science.gov (United States)

    Bystrický, E.; Kristeková, M.; Moczo, P.; Cipciar, A.; Fojtíková, L.; Pažák, P.; Gális, M.

    2009-04-01

    Two seismic networks are operated on the territory of the Slovak republic by two academic institutions. The Geophysical Institute of the Slovak Academy of Sciences operates the Slovak National Network of Seismic Stations (SNNSS, established in 2004) and the Faculty of Mathematics, Physics and Informatics, Comenius University Bratislava operates the Local Seismic Network Eastern Slovakia (LSNES, established in 2007). SNNSS is focused on the regional seismicity and participates in the international data exchange on a regular basis. LSNES, designed to be compatible and complementary with the existing SNNSS infrastructure, is focused on the seismicity of the eastern Slovakia source zone. The two networks share database and archive. Thus the expenses and workload of the joint data center operation are split between the two institutions. The cooperation enhances the overall reliability of the data center while does not interfere with the original scopes of the two networks. Relational database with thin client based on the standard web browser is implemented. Maintenance requirements of clients are reduced to minimum and it is easier to manage the system integrity. The database manages parametric data, macroseismic data, waveform data, inventory data, and geographic data. The database is not only a central part of the data processing of the two institutions; it also forms a core of the warning system. The warning system functionality requires development of the modules which are additional to the standard seismic database functionality. The modules for editing, publishing and automatic processing of macroseismic questionnaires were implemented for the purpose of the warning system, and the database integrates macroseismic data with other seismic data.

  15. Spatiotemporal patterns, triggers and anatomies of seismically detected rockfalls

    Science.gov (United States)

    Dietze, Michael; Turowski, Jens M.; Cook, Kristen L.; Hovius, Niels

    2017-11-01

    Rockfalls are a ubiquitous geomorphic process and a natural hazard in steep landscapes across the globe. Seismic monitoring can provide precise information on the timing, location and event anatomy of rockfalls, which are parameters that are otherwise hard to constrain. By pairing data from 49 seismically detected rockfalls in the Lauterbrunnen Valley in the Swiss Alps with auxiliary meteorologic and seismic data of potential triggers during autumn 2014 and spring 2015, we are able to (i) analyse the evolution of single rockfalls and their common properties, (ii) identify spatial changes in activity hotspots (iii) and explore temporal activity patterns on different scales ranging from months to minutes to quantify relevant trigger mechanisms. Seismic data allow for the classification of rockfall activity into two distinct phenomenological types. The signals can be used to discern multiple rock mass releases from the same spot, identify rockfalls that trigger further rockfalls and resolve modes of subsequent talus slope activity. In contrast to findings based on discontinuous methods with integration times of several months, rockfall in the monitored limestone cliff is not spatially uniform but shows a systematic downward shift of a rock mass release zone following an exponential law, most likely driven by a continuously lowering water table. Freeze-thaw transitions, approximated at first order from air temperature time series, account for only 5 out of the 49 rockfalls, whereas 19 rockfalls were triggered by rainfall events with a peak lag time of 1 h. Another 17 rockfalls were triggered by diurnal temperature changes and occurred during the coldest hours of the day and during the highest temperature change rates. This study is thus the first to show direct links between proposed rockfall triggers and the spatiotemporal distribution of rockfalls under natural conditions; it extends existing models by providing seismic observations of the rockfall process prior to

  16. OGC Web Services standards by example : the European Seismic Portal

    Science.gov (United States)

    Frobert, L.; Kamb, L.; Trani, L.; Spinuso, A.; Bossu, R.; Van Eck, T.

    2011-12-01

    NERIES (2006-2010) was an Integrated Infrastructure Initiative (I3) project in the Sixth Framework Program (FP6) of the European Commission (EC), aiming at networking the European seismic networks, improving access to data, allowing access to specific seismic infrastructures and pursuing targeted research developing the next generation of tools for improved service and data analysis. During this project, a web portal was developed using web services to access data and a Visual Web Applications to display them. However these web services were not conform to any standard, making them difficult to consume by any new user interface. Therefore, for the NERA project, the follow-up of NERIES, we have proposed the use of web services standards to access our data. We have decided to use standards defined by the Open Geospatial Consortium (OGC). The OGC defines standards for the Web service interfaces to access geo-tagged data. The events and seismic stations are also geo-tagged making these web services suitable for our purpose. Using standard web services gives us the opportunity to distribute our data across all conformant consumers to these standards through various programming languages and applications We have implemented a preliminary version of web services conforming to the Web Map Service (WMS) and Web Feature Service (WFS) standard to access our catalog of seismic events (nearly 200 000 events). To visualize them we have made four examples demo on our web site using different technologies (Adobe Flash, JavaScript, Java with Nasa World Wind and UDig a desktop GIS application). In the future we hope to implement other OGC Web services standard like : - Sensor Observation Service (SOS) to provide seismic waveform records; - Web Notification Service (WNS); - Catalog Service for the Web (CSW) to provide a search engine of all our web services; - Web Processing Service (WPS) to process data between different services. The power of the use of OGC standards is the easy

  17. Seismic Design of ITER Component Cooling Water System-1 Piping

    Science.gov (United States)

    Singh, Aditya P.; Jadhav, Mahesh; Sharma, Lalit K.; Gupta, Dinesh K.; Patel, Nirav; Ranjan, Rakesh; Gohil, Guman; Patel, Hiren; Dangi, Jinendra; Kumar, Mohit; Kumar, A. G. A.

    2017-04-01

    The successful performance of ITER machine very much depends upon the effective removal of heat from the in-vessel components and other auxiliary systems during Tokamak operation. This objective will be accomplished by the design of an effective Cooling Water System (CWS). The optimized piping layout design is an important element in CWS design and is one of the major design challenges owing to the factors of large thermal expansion and seismic accelerations; considering safety, accessibility and maintainability aspects. An important sub-system of ITER CWS, Component Cooling Water System-1 (CCWS-1) has very large diameter of pipes up to DN1600 with many intersections to fulfill the process flow requirements of clients for heat removal. Pipe intersection is the weakest link in the layout due to high stress intensification factor. CCWS-1 piping up to secondary confinement isolation valves as well as in-between these isolation valves need to survive a Seismic Level-2 (SL-2) earthquake during the Tokamak operation period to ensure structural stability of the system in the Safe Shutdown Earthquake (SSE) event. This paper presents the design, qualification and optimization of layout of ITER CCWS-1 loop to withstand SSE event combined with sustained and thermal loads as per the load combinations defined by ITER and allowable limits as per ASME B31.3, This paper also highlights the Modal and Response Spectrum Analyses done to find out the natural frequency and system behavior during the seismic event.

  18. Seismic monitoring of small alpine rockfalls - validity, precision and limitations

    Science.gov (United States)

    Dietze, Michael; Mohadjer, Solmaz; Turowski, Jens M.; Ehlers, Todd A.; Hovius, Niels

    2017-10-01

    Rockfall in deglaciated mountain valleys is perhaps the most important post-glacial geomorphic process for determining the rates and patterns of valley wall erosion. Furthermore, rockfall poses a significant hazard to inhabitants and motivates monitoring efforts in populated areas. Traditional rockfall detection methods, such as aerial photography and terrestrial laser scanning (TLS) data evaluation, provide constraints on the location and released volume of rock but have limitations due to significant time lags or integration times between surveys, and deliver limited information on rockfall triggering mechanisms and the dynamics of individual events. Environmental seismology, the study of seismic signals emitted by processes at the Earth's surface, provides a complementary solution to these shortcomings. However, this approach is predominantly limited by the strength of the signals emitted by a source and their transformation and attenuation towards receivers. To test the ability of seismic methods to identify and locate small rockfalls, and to characterise their dynamics, we surveyed a 2.16 km2 large, near-vertical cliff section of the Lauterbrunnen Valley in the Swiss Alps with a TLS device and six broadband seismometers. During 37 days in autumn 2014, 10 TLS-detected rockfalls with volumes ranging from 0.053 ± 0.004 to 2.338 ± 0.085 m3 were independently detected and located by the seismic approach, with a deviation of 81-29+59 m (about 7 % of the average inter-station distance of the seismometer network). Further potential rockfalls were detected outside the TLS-surveyed cliff area. The onset of individual events can be determined within a few milliseconds, and their dynamics can be resolved into distinct phases, such as detachment, free fall, intermittent impact, fragmentation, arrival at the talus slope and subsequent slope activity. The small rockfall volumes in this area require significant supervision during data processing: 2175 initially picked

  19. Seismic imaging of slab metamorphism and genesis of intermediate-depth intraslab earthquakes

    Science.gov (United States)

    Hasegawa, Akira; Nakajima, Junichi

    2017-12-01

    We review studies of intermediate-depth seismicity and seismic imaging of the interior of subducting slabs in relation to slab metamorphism and their implications for the genesis of intermediate-depth earthquakes. Intermediate-depth events form a double seismic zone in the depth range of c. 40-180 km, which occur only at locations where hydrous minerals are present, and are particularly concentrated along dehydration reaction boundaries. Recent studies have revealed detailed spatial distributions of these events and a close relationship with slab metamorphism. Pressure-temperature paths of the crust for cold slabs encounter facies boundaries with large H2O production rates and positive to