Regional seismic observations of the Non-Proliferation Experiment at the Livermore NTS Network

Energy Technology Data Exchange (ETDEWEB)

Walter, W.R.; Mayeda, K.; Patton, H.J. [Lawrence Livermore National Lab., CA (United States)] [and others

1994-12-31

The Non-Proliferation Experiment (NPE), a 1-kiloton chemical explosion in N-tunnel at Rainier Mesa on the Nevada Test Site (NTS), was recorded by the four station, regional seismic Livermore NTS Network, (LNN). In this study we compare the NPE`s seismic yield, frequency content, and discrimination performance with other NTS events recorded at LNN. Preliminary findings include: The NPE LNN average magnitudes are 4.16 for m{sub b}(P{sub n}) and 4.59 for m{sub b}(L{sub g}). Using published magnitude-yield relations gives nuclear equivalent yields of 2.3 and 2.2 kilotons respectively, implying enhanced coupling of chemical relative to nuclear explosions. A comparison of the NPE seismograms with those with similar magnitude N-tunnel nuclear explosions shows remarkable similarity over the frequency band 0.5 to 5.0 Hz. Outside this band the explosions show more variability, with the NPE having the least relative energy below 0.5 Hz and the most energy above 5 Hz when scaled by magnitude. Considering the variability within the N-tunnel nuclear explosions, these low- and high-frequency NPE-nuclear differences may not reflect chemical-nuclear source differences. The NPE was compared to a large number of NTS nuclear explosions and earthquakes as part of an ongoing short-period discrimination study of P{sub N}/L{sub g},P{sub g}/L{sub g}, and spectral ratios in the P{sub n}, P{sub g},L{sub g}, and coda phases. For these discriminants, the NPE looks very similar to N-tunnel nuclear explosions and other NTS nuclear explosions, implying seismic identification of contained, non-ripple-fired, chemical explosions as non-nuclear may not be possible. However, such blasts might serve as surrogate nuclear explosions when calibrating seismic discriminants in regions where nuclear testing has not occurred.

Neural network approach to the prediction of seismic events based on low-frequency signal monitoring of the Kuril-Kamchatka and Japanese regions

Directory of Open Access Journals (Sweden)

Irina Popova

2013-08-01

Full Text Available Very-low-frequency/ low-frequency (VLF/LF sub-ionospheric radiowave monitoring has been widely used in recent years to analyze earthquake preparatory processes. The connection between earthquakes with M ≥5.5 and nighttime disturbances of signal amplitude and phase has been established. Thus, it is possible to use nighttime anomalies of VLF/LF signals as earthquake precursors. Here, we propose a method for estimation of the VLF/LF signal sensitivity to seismic processes using a neural network approach. We apply the error back-propagation technique based on a three-level perceptron to predict a seismic event. The back-propagation technique involves two main stages to solve the problem; namely, network training, and recognition (the prediction itself. To train a neural network, we first create a so-called ‘training set’. The ‘teacher’ specifies the correspondence between the chosen input and the output data. In the present case, a representative database includes both the LF data received over three years of monitoring at the station in Petropavlovsk-Kamchatsky (2005-2007, and the seismicity parameters of the Kuril-Kamchatka and Japanese regions. At the first stage, the neural network established the relationship between the characteristic features of the LF signal (the mean and dispersion of a phase and an amplitude at nighttime for a few days before a seismic event and the corresponding level of correlation with a seismic event, or the absence of a seismic event. For the second stage, the trained neural network was applied to predict seismic events from the LF data using twelve time intervals in 2004, 2005, 2006 and 2007. The results of the prediction are discussed.

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

Science.gov (United States)

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

2016-04-01

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

NCSRR digital seismic network in Romania

International Nuclear Information System (INIS)

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

2007-01-01

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

Multi-parameter observations in the Ibero-Moghrebian region: the Western Mediterranean seismic network (WM) and ROA GPS geodynamic network

Science.gov (United States)

Pazos, Antonio; Martín Davila, José; Buforn, Elisa; Gárate Pasquín, Jorge; Catalán Morollón, Manuel; Hanka, Winfried; Udías, Agustín.; Benzzeghoud, Mourad; Harnafi, Mimoun

2010-05-01

The plate boundary between Eurasia and Africa plates crosses the called "Ibero-Maghrebian" region from the San Vicente Cape (SW Portugal) to Tunisia including the South of Iberia, Alboran Sea, and northern Morocco and Algeria. In this area, the convergence, with a low rate, is accommodated over a wide and diffuse deformation zone, characterized by a significant and widespread moderate seismic activity [Buforn et al., 1995], and the occurrence of large earthquakes is separated by long time intervals. Since more than hundred years ago San Fernando Naval Observatory (ROA), in collaboration with other Institutes, has deployed different geophysical and geodetic equipment in the Southern Spain - North-western Africa area in order to study this broad deformation zone. Currently a Broad Band seismic net (Western Mediterranean, WM net) is deployed, in collaboration with other institutions, around the Gulf of Cádiz and the Alboran sea, with stations in the South of Iberia and in North Africa (at Spanish places and Morocco), together with the seismic stations a permanent geodetic GPS net is co-installed at the same sites. Also, other geophysical instruments have been installed: a Satellite Laser Ranging (SLR) station at San Fernando Observatory Headquarter, a Geomagnetic Observatory in Cádiz bay area and some meteorological stations. These networks have been recently improved with the deployment of a new submarine and on-land geophysical observatory in the Alboran island (ALBO Observatory), where a permanent GPS, a meteorological station were installed on land and a permanent submarine observatory in 50 meters depth was also deploy in last October (with a broad band seismic sensor, a 3 C accelerometer and a DPG). This work shows the present status and the future plans of these networks and some results.

MyShake: Building a smartphone seismic network

Science.gov (United States)

Kong, Q.; Allen, R. M.; Schreier, L.

2014-12-01

We are in the process of building up a smartphone seismic network. In order to build this network, we did shake table tests to evaluate the performance of the smartphones as seismic recording instruments. We also conducted noise floor test to find the minimum earthquake signal we can record using smartphones. We added phone noises to the strong motion data from past earthquakes, and used these as an analogy dataset to test algorithms and to understand the difference of using the smartphone network and the traditional seismic network. We also built a prototype system to trigger the smartphones from our server to record signals which can be sent back to the server in near real time. The phones can also be triggered by our developed algorithm running locally on the phone, if there's an earthquake occur to trigger the phones, the signal recorded by the phones will be sent back to the server. We expect to turn the prototype system into a real smartphone seismic network to work as a supplementary network to the existing traditional seismic network.

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

Science.gov (United States)

Gaebler, Peter J.; Ceranna, Lars

2016-04-01

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

Optimization of Broadband Seismic Network in the Kingdom of Saudi Arabia

KAUST Repository

Alshuhail, Abdulrahman

2011-05-01

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

Amplitude Analysis and Modeling of Regional Phases in PNE Profiles in Northern Eurasia and Seismic Regionalization

National Research Council Canada - National Science Library

Morozov, Igor B; Li, Hongyan; Morozova, Elena; Duenow, Joel; Zheng, Haishan; Smithson, Scott B

2006-01-01

... is necessary to use regional phases for nuclear test monitoring. Over the past decades, Russian scientists acquired a network of dense, linear, long range, three-component Deep Seismic Sounding (DSS...

Romanian Educational Seismic Network Project

Science.gov (United States)

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

2013-04-01

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

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

International Nuclear Information System (INIS)

Saari, J.; Malm, M.

2011-11-01

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

Building a Smartphone Seismic Network

Science.gov (United States)

Kong, Q.; Allen, R. M.

2013-12-01

We are exploring to build a new type of seismic network by using the smartphones. The accelerometers in smartphones can be used to record earthquakes, the GPS unit can give an accurate location, and the built-in communication unit makes the communication easier for this network. In the future, these smartphones may work as a supplement network to the current traditional network for scientific research and real-time applications. In order to build this network, we developed an application for android phones and server to record the acceleration in real time. These records can be sent back to a server in real time, and analyzed at the server. We evaluated the performance of the smartphone as a seismic recording instrument by comparing them with high quality accelerometer while located on controlled shake tables for a variety of tests, and also the noise floor test. Based on the daily human activity data recorded by the volunteers and the shake table tests data, we also developed algorithm for the smartphones to detect earthquakes from daily human activities. These all form the basis of setting up a new prototype smartphone seismic network in the near future.

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

International Nuclear Information System (INIS)

Saari, J.; Malm, M.

2014-05-01

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

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

Science.gov (United States)

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

2017-12-01

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

Recent Vs. Historical Seismicity Analysis For Banat Seismic Region (Western Part Of Romania)

OpenAIRE

Oros Eugen; Diaconescu Mihai

2015-01-01

The present day seismic activity from a region reflects the active tectonics and can confirm the seismic potential of the seismogenic sources as they are modelled using the historical seismicity. This paper makes a comparative analysis of the last decade seismicity recorded in the Banat Seismic Region (western part of Romania) and the historical seismicity of the region (Mw≥4.0). Four significant earthquake sequences have been recently localized in the region, three of them nearby the city of...

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

International Nuclear Information System (INIS)

Saari, J.; Lakio, A.

2008-05-01

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

A national seismographic network for assessing seismic hazards

International Nuclear Information System (INIS)

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

1989-01-01

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

Criteria for the PNE seismic network

International Nuclear Information System (INIS)

Pruvost, N.L.

1978-01-01

A 1976 treaty between the United States and the Soviet Union permits a local seismic network to be deployed at the site of a peaceful nuclear explosion to monitor the event. Criteria for the design and selection of the data-acquisition equipment for such a network are provided. Constraints imposed by the protocol of the treaty, the environment, and the expected properties of seismic signals (based on experiences at the Nevada Test Site) are discussed. Conclusions are drawn about the desired operating mode. Criteria for a general seismic instrumentation system are described

Automated seismic detection of landslides at regional scales: a Random Forest based detection algorithm

Science.gov (United States)

Hibert, C.; Michéa, D.; Provost, F.; Malet, J. P.; Geertsema, M.

2017-12-01

Detection of landslide occurrences and measurement of their dynamics properties during run-out is a high research priority but a logistical and technical challenge. Seismology has started to help in several important ways. Taking advantage of the densification of global, regional and local networks of broadband seismic stations, recent advances now permit the seismic detection and location of landslides in near-real-time. This seismic detection could potentially greatly increase the spatio-temporal resolution at which we study landslides triggering, which is critical to better understand the influence of external forcings such as rainfalls and earthquakes. However, detecting automatically seismic signals generated by landslides still represents a challenge, especially for events with small mass. The low signal-to-noise ratio classically observed for landslide-generated seismic signals and the difficulty to discriminate these signals from those generated by regional earthquakes or anthropogenic and natural noises are some of the obstacles that have to be circumvented. We present a new method for automatically constructing instrumental landslide catalogues from continuous seismic data. We developed a robust and versatile solution, which can be implemented in any context where a seismic detection of landslides or other mass movements is relevant. The method is based on a spectral detection of the seismic signals and the identification of the sources with a Random Forest machine learning algorithm. The spectral detection allows detecting signals with low signal-to-noise ratio, while the Random Forest algorithm achieve a high rate of positive identification of the seismic signals generated by landslides and other seismic sources. The processing chain is implemented to work in a High Performance Computers centre which permits to explore years of continuous seismic data rapidly. We present here the preliminary results of the application of this processing chain for years

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

International Nuclear Information System (INIS)

Saari, J.; Malm, M.

2014-06-01

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

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

International Nuclear Information System (INIS)

Saari, J.; Malm, M.

2012-06-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-06-15

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

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

Directory of Open Access Journals (Sweden)

Milena Moretti

2016-12-01

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

Automatic Seismic-Event Classification with Convolutional Neural Networks.

Science.gov (United States)

Bueno Rodriguez, A.; Titos Luzón, M.; Garcia Martinez, L.; Benitez, C.; Ibáñez, J. M.

2017-12-01

Active volcanoes exhibit a wide range of seismic signals, providing vast amounts of unlabelled volcano-seismic data that can be analyzed through the lens of artificial intelligence. However, obtaining high-quality labelled data is time-consuming and expensive. Deep neural networks can process data in their raw form, compute high-level features and provide a better representation of the input data distribution. These systems can be deployed to classify seismic data at scale, enhance current early-warning systems and build extensive seismic catalogs. In this research, we aim to classify spectrograms from seven different seismic events registered at "Volcán de Fuego" (Colima, Mexico), during four eruptive periods. Our approach is based on convolutional neural networks (CNNs), a sub-type of deep neural networks that can exploit grid structure from the data. Volcano-seismic signals can be mapped into a grid-like structure using the spectrogram: a representation of the temporal evolution in terms of time and frequency. Spectrograms were computed from the data using Hamming windows with 4 seconds length, 2.5 seconds overlapping and 128 points FFT resolution. Results are compared to deep neural networks, random forest and SVMs. Experiments show that CNNs can exploit temporal and frequency information, attaining a classification accuracy of 93%, similar to deep networks 91% but outperforming SVM and random forest. These results empirically show that CNNs are powerful models to classify a wide range of volcano-seismic signals, and achieve good generalization. Furthermore, volcano-seismic spectrograms contains useful discriminative information for the CNN, as higher layers of the network combine high-level features computed for each frequency band, helping to detect simultaneous events in time. Being at the intersection of deep learning and geophysics, this research enables future studies of how CNNs can be used in volcano monitoring to accurately determine the detection and

Full Seismic Waveform Tomography of the Japan region using Adjoint Methods

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Steptoe, Hamish; Fichtner, Andreas; Rickers, Florian; Trampert, Jeannot

2013-04-01

We present a full-waveform tomographic model of the Japan region based on spectral-element wave propagation, adjoint techniques and seismic data from dense station networks. This model is intended to further our understanding of both the complex regional tectonics and the finite rupture processes of large earthquakes. The shallow Earth structure of the Japan region has been the subject of considerable tomographic investigation. The islands of Japan exist in an area of significant plate complexity: subduction related to the Pacific and Philippine Sea plates is responsible for the majority of seismicity and volcanism of Japan, whilst smaller micro-plates in the region, including the Okhotsk, and Okinawa and Amur, part of the larger North America and Eurasia plates respectively, contribute significant local intricacy. In response to the need to monitor and understand the motion of these plates and their associated faults, numerous seismograph networks have been established, including the 768 station high-sensitivity Hi-net network, 84 station broadband F-net and the strong-motion seismograph networks K-net and KiK-net in Japan. We also include the 55 station BATS network of Taiwan. We use this exceptional coverage to construct a high-resolution model of the Japan region from the full-waveform inversion of over 15,000 individual component seismograms from 53 events that occurred between 1997 and 2012. We model these data using spectral-element simulations of seismic wave propagation at a regional scale over an area from 120°-150°E and 20°-50°N to a depth of around 500 km. We quantify differences between observed and synthetic waveforms using time-frequency misfits allowing us to separate both phase and amplitude measurements whilst exploiting the complete waveform at periods of 15-60 seconds. Fréchet kernels for these misfits are calculated via the adjoint method and subsequently used in an iterative non-linear conjugate-gradient optimization. Finally, we employ

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

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

2017-12-01

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

Earthquake Monitoring: SeisComp3 at the Swiss National Seismic Network

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

2011-12-01

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

Earthquake Monitoring with the MyShake Global Smartphone Seismic Network

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Inbal, A.; Kong, Q.; Allen, R. M.; Savran, W. H.

2017-12-01

Smartphone arrays have the potential for significantly improving seismic monitoring in sparsely instrumented urban areas. This approach benefits from the dense spatial coverage of users, as well as from communication and computational capabilities built into smartphones, which facilitate big seismic data transfer and analysis. Advantages in data acquisition with smartphones trade-off with factors such as the low-quality sensors installed in phones, high noise levels, and strong network heterogeneity, all of which limit effective seismic monitoring. Here we utilize network and array-processing schemes to asses event detectability with the MyShake global smartphone network. We examine the benefits of using this network in either triggered or continuous modes of operation. A global database of ground motions measured on stationary phones triggered by M2-6 events is used to establish detection probabilities. We find that the probability of detecting an M=3 event with a single phone located 20 nearby phones closely match the regional catalog locations. We use simulated broadband seismic data to examine how location uncertainties vary with user distribution and noise levels. To this end, we have developed an empirical noise model for the metropolitan Los-Angeles (LA) area. We find that densities larger than 100 stationary phones/km2 are required to accurately locate M 2 events in the LA basin. Given the projected MyShake user distribution, that condition may be met within the next few years.

Adding seismic broadband analysis to characterize Andean backarc seismicity in Argentina

Science.gov (United States)

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

2007-05-01

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

Regional passive seismic monitoring reveals dynamic glacier activity on Spitsbergen, Svalbard

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Andreas Köhler

2015-12-01

Full Text Available Dynamic glacier activity is increasingly observed through passive seismic monitoring. We analysed near-regional-scale seismicity on the Arctic archipelago of Svalbard to identify seismic icequake signals and to study their spatial–temporal distribution within the 14-year period from 2000 until 2013. This is the first study that uses seismic data recorded on permanent broadband stations to detect and locate icequakes in different regions of Spitsbergen, the main island of the archipelago. A temporary local seismic network and direct observations of glacier calving and surging were used to identify icequake sources. We observed a high number of icequakes with clear spectral peaks between 1 and 8 Hz in different parts of Spitsbergen. Spatial clusters of icequakes could be associated with individual grounded tidewater glaciers and exhibited clear seasonal variability each year with more signals observed during the melt season. Locations at the termini of glaciers, and correlation with visual calving observations in situ at Kronebreen, a glacier in the Kongsfjorden region, show that these icequakes were caused dominantly by calving. Indirect evidence for glacier surging through increased calving seismicity was found in 2003 at Tunabreen, a glacier in central Spitsbergen. Another type of icequake was observed in the area of the Nathorstbreen glacier system. Seismic events occurred upstream of the glacier within a short time period between January and May 2009 during the initial phase of a major glacier surge. This study is the first step towards the generation and implementation of an operational seismic monitoring strategy for glacier dynamics in Svalbard.

A dense microseismic monitoring network in Korea for uncovering relationship between seismic activity and neotectonic features

Science.gov (United States)

Kang, T.; Lee, J. M.; Kim, W.; Jo, B. G.; Chung, T.; Choi, S.

2012-12-01

A few tens of surface traces indicating movements in Quaternary were found in the southeastern part of the Korean Peninsula. Following both the geological and engineering definitions, those features are classified into "active", in geology, or "capable", in engineering, faults. On the other hand, the present-day seismicity of the region over a couple of thousand years is indistinguishable on the whole with the rest of the Korean Peninsula. It is therefore of great interest whether the present seismic activity is related to the neotectonic features or not. Either of conclusions is not intuitive in terms of the present state of seismic monitoring network in the region. Thus much interest in monitoring seismicity to provide an improved observation resolution and to lower the event-detection threshold has increased with many observations of the Quaternary faults. We installed a remote, wireless seismograph network which is composed of 20 stations with an average spacing of 10 km. Each station is equipped with a three-component Trillium Compact seismometer and Taurus digitizer. Instrumentation and analysis advancements are now offering better tools for this monitoring. This network is scheduled to be in operation over about one and a half year. In spite of the relatively short observation period, we expect that the high density of the network enables us to monitor seismic events with much lower magnitude threshold compared to the preexisting seismic network in the region. Following the Gutenberg-Richter relationship, the number of events with low magnitude is logarithmically larger than that with high magnitude. Following this rule, we can expect that many of microseismic events may reveal behavior of their causative faults, if any. We report the results of observation which has been performed over a year up to now.

Caltech/USGS Southern California Seismic Network: Recent Developments

Science.gov (United States)

Bhadha, R.; Chen, S.; Crummey, J.; Hauksson, E.; Solanki, K.; Thomas, V. I.; Watkins, M.; Yip, R.; Yu, E.; Given, D.; Peats, R.; Schwarz, S.

2010-12-01

The SCSN is the modern digital ground motion seismic network in Southern California and performs the following tasks: 1) Operates remote seismic stations and the central data processing systems in Pasadena; 2) Generates and reports real-time products including location, magnitude, ShakeMap, and others; 3) Responds to FEMA, CalEMA, media, and public inquiries about earthquakes; 4) Manages the production, archival, and distribution of waveforms, phase picks, and other data at the SCEDC; 5) Contributes to development and maintenance of the ANSS Quake Monitoring System (AQMS) software to add new features and improve robustness; 6) Supports the deployment of AQMS to other ANSS member regional seismic networks. The public regularly accesses the CISN, SCSN, and SCEDC web pages for up-to-date quake info and more than 230,000 users subscribe to the Electronic Notification System (ENS) which sends rapid notifications via email and cell phones. We distribute our products via Internet (EIDS), email, and paging, to USGS in Reston and Golden, FEMA, CalEMA, local governments, partner members, and other subscribers. We have developed CISN Display and provide ShakeCast for customers who require real-time earthquake information. The SCSN also exchanges waveform, phase pick, and amplitude data in real-time with several other partner networks, including Menlo Park, UCB, UNR, Anza network, the Tsunami Warning Centers, IRIS, and the NEIC. We operate a number of 24/7 on-call rotations to provide quick response to verify seismic events as well as addressing systems and telemetry issues. As part of our goals to improve quality, robustness, and coverage, some of our recent efforts include: 1) Converting the digital stations in the network to Q330 dataloggers; 2) Developing command and control capabilities such as automated mass re-centering; 3) Migration from serial to Ethernet communications; 4) Clustering of data acquisition servers for fail-over to improve data availability; 5) Use of

Recent Vs. Historical Seismicity Analysis For Banat Seismic Region (Western Part Of Romania

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Oros Eugen

2015-03-01

Full Text Available The present day seismic activity from a region reflects the active tectonics and can confirm the seismic potential of the seismogenic sources as they are modelled using the historical seismicity. This paper makes a comparative analysis of the last decade seismicity recorded in the Banat Seismic Region (western part of Romania and the historical seismicity of the region (Mw≥4.0. Four significant earthquake sequences have been recently localized in the region, three of them nearby the city of Timisoara (January 2012 and March 2013 and the fourth within Hateg Basin, South Carpathians (October 2013. These sequences occurred within the epicentral areas of some strong historical earthquakes (Mw≥5.0. The main events had some macroseismic effects on people up to some few kilometers from the epicenters. Our results update the Romanian earthquakes catalogue and bring new information along the local seismic hazard sources models and seismotectonics.

An Assessment of the Seismicity of the Bursa Region from a Temporary Seismic Network

Science.gov (United States)

Gok, Elcin; Polat, Orhan

2012-04-01

A temporary earthquake station network of 11 seismological recorders was operated in the Bursa region, south of the Marmara Sea in the northwest of Turkey, which is located at the southern strand of the North Anatolian Fault Zone (NAFZ). We located 384 earthquakes out of a total of 582 recorded events that span the study area between 28.50-30.00°E longitudes and 39.75-40.75°N latitudes. The depth of most events was found to be less than 29 km, and the magnitude interval ranges were between 0.3 ≤ ML ≤ 5.4, with RMS less than or equal to 0.2. Seismic activities were concentrated southeast of Uludag Mountain (UM), in the Kestel-Igdir area and along the Gemlik Fault (GF). In the study, we computed 10 focal mechanisms from temporary and permanents networks. The predominant feature of the computed focal mechanisms is the relatively widespread near horizontal northwest-southeast (NW-SE) T-axis orientation. These fault planes have been used to obtain the orientation and shape factor (R, magnitude stress ratio) of the principal stress tensors (σ1, σ2, σ3). The resulting stress tensors reveal σ1 closer to the vertical (oriented NE-SW) and σ2, σ3 horizontal with R = 0.5. These results confirm that Bursa and its vicinity could be defined by an extensional regime showing a primarily normal to oblique-slip motion character. It differs from what might be expected from the stress tensor inversion for the NAFZ. Different fault patterns related to structural heterogeneity from the north to the south in the study area caused a change in the stress regime from strike-slip to normal faulting.

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.

Processing of seismic signals from a seismometer network

International Nuclear Information System (INIS)

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

1983-08-01

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

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

Science.gov (United States)

Kvavadze, N.; Tsereteli, N. S.

2017-12-01

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

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

International Nuclear Information System (INIS)

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

1991-01-01

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

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

International Nuclear Information System (INIS)

Saari, J.; Malm, M.

2010-06-01

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

Passive seismic experiment in the Olduvai Gorge and Laetoli region (Ngorongoro Conservation Area), Northern Tanzania.

Science.gov (United States)

Parisi, Laura; Lombardo, Luigi; Tang, Zheng; Mai, P. Martin

2017-04-01

The Olduvai Gorge and Laetoli basins, located within the Ngorogoro Conservation Area (NCA), are a cornerstone for understanding the evolution of early humans and are two paleo-antropological excavation sites of global importance. NCA is located at the boundary between the Tanzanian Craton and East African Rift (EAR), in the vicinity of Ngorongoro Crater and other major volcanic edifices. Thus, understanding the geology and tectonics of the NCA may shed light onto the question why early Hominins settled in this region. Environmental and geological conditions in the Olduvai and Laetoli region that promoted human settlement and development are still debated by geologists and paleo-anthropologists. Paleo-geographical reconstructions of the study area of the last 2 million years may take advantage of modern passive seismology. Therefore, we installed a dense seismic network covering a surface of approximately 30 x 40 km within the NCA to map the depth extent of known faults, and to identify seismically active faults that have no surface expression. Our ten seismic stations, equipped with Trillium Compact 120 s sensors, started to operate in June 2016 and will continue for a total of 2 years. At the end of the first year, other 5 stations will densify our network. Here we analyse data quality of the first four months of continuous recordings. Our network provides good quality 3-C waveforms in the frequency range of 0.7-50 Hz. Vertical component seismograms record frequencies reliably down to 8 mHz. Preliminary results of the seismicity obtained with standard location procedures show that NCA is characterised by frequent tectonic seismicity (not volcano-related) with Ml between 0.5 and 2.0. Seismic activity is more frequent in the South (Laetoli region) where major fault systems have not been recognised at the surface yet.

MyShake: A smartphone seismic network for earthquake early warning and beyond.

Science.gov (United States)

Kong, Qingkai; Allen, Richard M; Schreier, Louis; Kwon, Young-Woo

2016-02-01

Large magnitude earthquakes in urban environments continue to kill and injure tens to hundreds of thousands of people, inflicting lasting societal and economic disasters. Earthquake early warning (EEW) provides seconds to minutes of warning, allowing people to move to safe zones and automated slowdown and shutdown of transit and other machinery. The handful of EEW systems operating around the world use traditional seismic and geodetic networks that exist only in a few nations. Smartphones are much more prevalent than traditional networks and contain accelerometers that can also be used to detect earthquakes. We report on the development of a new type of seismic system, MyShake, that harnesses personal/private smartphone sensors to collect data and analyze earthquakes. We show that smartphones can record magnitude 5 earthquakes at distances of 10 km or less and develop an on-phone detection capability to separate earthquakes from other everyday shakes. Our proof-of-concept system then collects earthquake data at a central site where a network detection algorithm confirms that an earthquake is under way and estimates the location and magnitude in real time. This information can then be used to issue an alert of forthcoming ground shaking. MyShake could be used to enhance EEW in regions with traditional networks and could provide the only EEW capability in regions without. In addition, the seismic waveforms recorded could be used to deliver rapid microseism maps, study impacts on buildings, and possibly image shallow earth structure and earthquake rupture kinematics.

Tectonic implications of seismic activity recorded by the northern Ontario seismograph network

International Nuclear Information System (INIS)

Wetmiller, R.J.; Cajka, M.G.

1989-01-01

The northern Ontario seismograph network, which has operated under the Canadian Nuclear Fuel Waste Management Program since 1982, has provided valuable data to supplement those recorded by the Canadian national networks on earthquake activity, rockburst activity, the distribution of regional seismic velocities, and the contemporary stress field in northern Ontario. The combined networks recorded the largest earthquake known in northwestern Ontario, M 3.9 near Sioux Lookout on February 11, 1984, and many smaller earthquakes in northeastern Ontario. Focal mechanism solutions of these and older events showed high horizontal stress and thrust faulting to be dominant features of the contemporary tectonics of northern Ontario. The zone of more intense earthquake activity in western Quebec appeared to extend northwestward into the Kapuskasing area of northeastern Ontario, where an area of persistent microearthquake activity had been identified by a seismograph station near Kapuskasing. Controlled explosions of the 1984 Kapuskasing Uplift seismic profile experiment recorded on the northern Ontario seismograph network showed the presence of anomalously high LG velocities in northeastern Ontario (3.65 km/s) that when properly taken into account reduced the mislocation errors of well-recorded seismic events by 50% on average

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

Science.gov (United States)

2007-09-20

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

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.

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

Science.gov (United States)

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

2007-12-01

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

Earthquake location determination using data from DOMERAPI and BMKG seismic networks: A preliminary result of DOMERAPI project

Energy Technology Data Exchange (ETDEWEB)

Ramdhan, Mohamad [Study Program of Earth Science, Institut Teknologi Bandung, Jl. Ganesa 10, Bandung, 40132 (Indonesia); Agency for Meteorology, Climatology and Geophysics of Indonesia (BMKG) Jl. Angkasa 1 No. 2 Kemayoran, Jakarta Pusat, 10720 (Indonesia); Nugraha, Andri Dian; Widiyantoro, Sri [Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut TeknologiBandung, Jl. Ganesa 10, Bandung, 40132 (Indonesia); Métaxian, Jean-Philippe [Institut de Recherche pour le Développement (IRD) (France); Valencia, Ayunda Aulia, E-mail: mohamad.ramdhan@bmkg.go.id [Study Program of Geophysical Engineering, Institut Teknologi Bandung, Jl. Ganesa 10, Bandung, 40132 (Indonesia)

2015-04-24

DOMERAPI project has been conducted to comprehensively study the internal structure of Merapi volcano, especially about deep structural features beneath the volcano. DOMERAPI earthquake monitoring network consists of 46 broad-band seismometers installed around the Merapi volcano. Earthquake hypocenter determination is a very important step for further studies, such as hypocenter relocation and seismic tomographic imaging. Ray paths from earthquake events occurring outside the Merapi region can be utilized to delineate the deep magma structure. Earthquakes occurring outside the DOMERAPI seismic network will produce an azimuthal gap greater than 180{sup 0}. Owing to this situation the stations from BMKG seismic network can be used jointly to minimize the azimuthal gap. We identified earthquake events manually and carefully, and then picked arrival times of P and S waves. The data from the DOMERAPI seismic network were combined with the BMKG data catalogue to determine earthquake events outside the Merapi region. For future work, we will also use the BPPTKG (Center for Research and Development of Geological Disaster Technology) data catalogue in order to study shallow structures beneath the Merapi volcano. The application of all data catalogues will provide good information as input for further advanced studies and volcano hazards mitigation.

Connection with seismic networks and construction of real time earthquake monitoring system

Energy Technology Data Exchange (ETDEWEB)

Chi, Heon Cheol; Lee, H. I.; Shin, I. C.; Lim, I. S.; Park, J. H.; Lee, B. K.; Whee, K. H.; Cho, C. S. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2000-12-15

It is natural to use the nuclear power plant seismic network which have been operated by KEPRI(Korea Electric Power Research Institute) and local seismic network by KIGAM(Korea Institute of Geology, Mining and Material). The real time earthquake monitoring system is composed with monitoring module and data base module. Data base module plays role of seismic data storage and classification and the other, monitoring module represents the status of acceleration in the nuclear power plant area. This research placed the target on the first, networking the KIN's seismic monitoring system with KIGAM and KEPRI seismic network and the second, construction the KIN's Independent earthquake monitoring system.

Connection with seismic networks and construction of real time earthquake monitoring system

International Nuclear Information System (INIS)

Chi, Heon Cheol; Lee, H. I.; Shin, I. C.; Lim, I. S.; Park, J. H.; Lee, B. K.; Whee, K. H.; Cho, C. S.

2000-12-01

It is natural to use the nuclear power plant seismic network which have been operated by KEPRI(Korea Electric Power Research Institute) and local seismic network by KIGAM(Korea Institute of Geology, Mining and Material). The real time earthquake monitoring system is composed with monitoring module and data base module. Data base module plays role of seismic data storage and classification and the other, monitoring module represents the status of acceleration in the nuclear power plant area. This research placed the target on the first, networking the KIN's seismic monitoring system with KIGAM and KEPRI seismic network and the second, construction the KIN's Independent earthquake monitoring system

Oklahoma seismic network

International Nuclear Information System (INIS)

Luza, K.V.; Lawson, J.E. Jr.; Univ. of Oklahoma, Norman, OK

1993-07-01

The US Nuclear Regulatory Commission has established rigorous guidelines that must be adhered to before a permit to construct a nuclear-power plant is granted to an applicant. Local as well as regional seismicity and structural relationships play an integral role in the final design criteria for nuclear power plants. The existing historical record of seismicity is inadequate in a number of areas of the Midcontinent region because of the lack of instrumentation and (or) the sensitivity of the instruments deployed to monitor earthquake events. The Nemaha Uplift/Midcontinent Geophysical Anomaly is one of five principal areas east of the Rocky Mountain front that has a moderately high seismic-risk classification. The Nemaha uplift, which is common to the states of Oklahoma, Kansas, and Nebraska, is approximately 415 miles long and 12-14 miles wide. The Midcontinent Geophysical Anomaly extends southward from Minnesota across Iowa and the southeastern corner of Nebraska and probably terminates in central Kansas. A number of moderate-sized earthquakes--magnitude 5 or greater--have occurred along or west of the Nemaha uplift. The Oklahoma Geological Survey, in cooperation with the geological surveys of Kansas, Nebraska, and Iowa, conducted a 5-year investigation of the seismicity and tectonic relationships of the Nemaha uplift and associated geologic features in the Midcontinent. This investigation was intended to provide data to be used to design nuclear-power plants. However, the information is also being used to design better large-scale structures, such as dams and high-use buildings, and to provide the necessary data to evaluate earthquake-insurance rates in the Midcontinent

Imaging of 3-D seismic velocity structure of Southern Sumatra region using double difference tomographic method

Energy Technology Data Exchange (ETDEWEB)

Lestari, Titik, E-mail: t2klestari@gmail.com [Meteorological Climatological and Geophysical Agency (MCGA), Jalan Angkasa I No.2 Kemayoran, Jakarta Pusat, 10720 (Indonesia); Faculty of Earth Science and Technology, Bandung Institute of Technology, Jalan Ganesa No.10, Bandung 40132 (Indonesia); Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id [Global Geophysical Research Group, Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology, Jalan Ganesa 10 Bandung 40132 (Indonesia)

2015-04-24

Southern Sumatra region has a high level of seismicity due to the influence of the subduction system, Sumatra fault, Mentawai fault and stretching zone activities. The seismic activities of Southern Sumatra region are recorded by Meteorological Climatological and Geophysical Agency (MCGA’s) Seismograph network. In this study, we used earthquake data catalog compiled by MCGA for 3013 events from 10 seismic stations around Southern Sumatra region for time periods of April 2009 – April 2014 in order to invert for the 3-D seismic velocities structure (Vp, Vs, and Vp/Vs ratio). We applied double-difference seismic tomography method (tomoDD) to determine Vp, Vs and Vp/Vs ratio with hypocenter adjustment. For the inversion procedure, we started from the initial 1-D seismic velocity model of AK135 and constant Vp/Vs of 1.73. The synthetic travel time from source to receiver was calculated using ray pseudo-bending technique, while the main tomographic inversion was applied using LSQR method. The resolution model was evaluated using checkerboard test and Derivative Weigh Sum (DWS). Our preliminary results show low Vp and Vs anomalies region along Bukit Barisan which is may be associated with weak zone of Sumatran fault and migration of partial melted material. Low velocity anomalies at 30-50 km depth in the fore arc region may indicated the hydrous material circulation because the slab dehydration. We detected low seismic seismicity in the fore arc region that may be indicated as seismic gap. It is coincides contact zone of high and low velocity anomalies. And two large earthquakes (Jambi and Mentawai) also occurred at the contact of contrast velocity.

Input for seismic hazard assessment using Vrancea seismic source region

International Nuclear Information System (INIS)

Ivan, Iren-Adelina; Enescu, B.D.; Pantea, A.

1998-01-01

We use an extended and combined data base including historical and modern, qualitative and quantitative data, i.e., more than 25 events during the period 1790 - 1990 with epicentral/maximum intensities ranging from X to V degree (MSK scale), the variation interval of isoseismal curves ranging from IX th to III rd degree. The data set was analysed using both the sum phasor techniques of Ridelek and Sacks (1984) for different magnitudes and depth intervals and the Stepp's method. For the assessment of seismic hazard we need a pattern of seismic source regions including an estimation for the maximum expected magnitude and the return period for the studied regions. Another necessary step in seismic hazard assessment is to develop attenuation relationships specific to a seismogenic zone, particularly to sub-crustal earthquakes of Vrancea region. The conceptual frame involves the use of appropriate decay models and consideration of the randomness in the attenuation, taking into account the azimuthal variation of the isoseist shapes. (authors)

Georgia-Armenia Transboarder seismicity studies

Science.gov (United States)

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

2012-12-01

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

Seismicity and seismic monitoring in the Asse salt mine

International Nuclear Information System (INIS)

Flach, D.; Gommlich, G.; Hente, B.

1987-01-01

Seismicity analyses are made in order to assess the safety of candidate sites for ultimate disposal of hazardous wastes. The report in hand reviews the seismicity history of the Asse salt mine and presents recent results of a measuring campaign made in the area. The monitoring network installed at the site supplies data and information on the regional seismicity, on seismic amplitudes under ground and above ground, and on microseismic activities. (DG) [de

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.

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

Optimizing Seismic Monitoring Networks for EGS and Conventional Geothermal Projects

Science.gov (United States)

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

2013-04-01

In the past several years, geological energy technologies receive growing attention and have been initiated in or close to urban areas. Some of these technologies involve injecting fluids into the subsurface (e.g., oil and gas development, waste disposal, and geothermal energy development) and have been found or suspected to cause small to moderate sized earthquakes. These earthquakes, which may have gone unnoticed in the past when they occurred in remote sparsely populated areas, are now posing a considerable risk for the public acceptance of these technologies in urban areas. The permanent termination of the EGS project in Basel, Switzerland after a number of induced ML~3 (minor) earthquakes in 2006 is one prominent example. It is therefore essential for the future development and success of these geological energy technologies to develop strategies for managing induced seismicity and keeping the size of induced earthquakes at a level that is acceptable to all stakeholders. Most guidelines and recommendations on induced seismicity published since the 1970ies conclude that an indispensable component of such a strategy is the establishment of seismic monitoring in an early stage of a project. This is because an appropriate seismic monitoring is the only way to detect and locate induced microearthquakes with sufficient certainty to develop an understanding of the seismic and geomechanical response of the reservoir to the geotechnical operation. In addition, seismic monitoring lays the foundation for the establishment of advanced traffic light systems and is therefore an important confidence building measure towards the local population and authorities. We have developed an optimization algorithm for seismic monitoring networks in urban areas that allows to design and evaluate seismic network geometries for arbitrary geotechnical operation layouts. The algorithm is based on the D-optimal experimental design that aims to minimize the error ellipsoid of the linearized

Hydraulic fracturing and the Crooked Lake Sequences: Insights gleaned from regional seismic networks

Science.gov (United States)

Schultz, Ryan; Stern, Virginia; Novakovic, Mark; Atkinson, Gail; Gu, Yu Jeffrey

2015-04-01

Within central Alberta, Canada, a new sequence of earthquakes has been recognized as of 1 December 2013 in a region of previous seismic quiescence near Crooked Lake, ~30 km west of the town of Fox Creek. We utilize a cross-correlation detection algorithm to detect more than 160 events to the end of 2014, which is temporally distinguished into five subsequences. This observation is corroborated by the uniqueness of waveforms clustered by subsequence. The Crooked Lake Sequences have come under scrutiny due to its strong temporal correlation (>99.99%) to the timing of hydraulic fracturing operations in the Duvernay Formation. We assert that individual subsequences are related to fracturing stimulation and, despite adverse initial station geometry, double-difference techniques allow us to spatially relate each cluster back to a unique horizontal well. Overall, we find that seismicity in the Crooked Lake Sequences is consistent with first-order observations of hydraulic fracturing induced seismicity.

Incorporating Low-Cost Seismometers into the Central Weather Bureau Seismic Network for Earthquake Early Warning in Taiwan

Directory of Open Access Journals (Sweden)

Da-Yi Chen

2015-01-01

Full Text Available A dense seismic network can increase Earthquake Early Warning (EEW system capability to estimate earthquake information with higher accuracy. It is also critical for generating fast, robust earthquake alarms before strong-ground shaking hits the target area. However, building a dense seismic network via traditional seismometers is too expensive and may not be practical. Using low-cost Micro-Electro Mechanical System (MEMS accelerometers is a potential solution to quickly deploy a large number of sensors around the monitored region. An EEW system constructed using a dense seismic network with 543 MEMS sensors in Taiwan is presented. The system also incorporates the official seismic network of _ Central Weather Bureau (CWB. The real-time data streams generated by the two networks are integrated using the Earthworm software. This paper illustrates the methods used by the integrated system for estimating earthquake information and evaluates the system performance. We applied the Earthworm picker for the seismograms recorded by the MEMS sensors (Chen et al. 2015 following new picking constraints to accurately detect P-wave arrivals and use a new regression equation for estimating earthquake magnitudes. An off-line test was implemented using 46 earthquakes with magnitudes ranging from ML 4.5 - 6.5 to calibrate the system. The experimental results show that the integrated system has stable source parameter results and issues alarms much faster than the current system run by the CWB seismic network (CWBSN.

xQuake: A Modern Approach to Seismic Network Analytics

Science.gov (United States)

Johnson, C. E.; Aikin, K. E.

2017-12-01

While seismic networks have expanded over the past few decades, and social needs for accurate and timely information has increased dramatically, approaches to the operational needs of both global and regional seismic observatories have been slow to adopt new technologies. This presentation presents the xQuake system that provides a fresh approach to seismic network analytics based on complexity theory and an adaptive architecture of streaming connected microservices as diverse data (picks, beams, and other data) flow into a final, curated catalog of events. The foundation for xQuake is the xGraph (executable graph) framework that is essentially a self-organizing graph database. An xGraph instance provides both the analytics as well as the data storage capabilities at the same time. Much of the analytics, such as synthetic annealing in the detection process and an evolutionary programing approach for event evolution, draws from the recent GLASS 3.0 seismic associator developed by and for the USGS National Earthquake Information Center (NEIC). In some respects xQuake is reminiscent of the Earthworm system, in that it comprises processes interacting through store and forward rings; not surprising as the first author was the lead architect of the original Earthworm project when it was known as "Rings and Things". While Earthworm components can easily be integrated into the xGraph processing framework, the architecture and analytics are more current (e.g. using a Kafka Broker for store and forward rings). The xQuake system is being released under an unrestricted open source license to encourage and enable sthe eismic community support in further development of its capabilities.

Cloud Computing Services for Seismic Networks

Science.gov (United States)

Olson, Michael

This thesis describes a compositional framework for developing situation awareness applications: applications that provide ongoing information about a user's changing environment. The thesis describes how the framework is used to develop a situation awareness application for earthquakes. The applications are implemented as Cloud computing services connected to sensors and actuators. The architecture and design of the Cloud services are described and measurements of performance metrics are provided. The thesis includes results of experiments on earthquake monitoring conducted over a year. The applications developed by the framework are (1) the CSN---the Community Seismic Network---which uses relatively low-cost sensors deployed by members of the community, and (2) SAF---the Situation Awareness Framework---which integrates data from multiple sources, including the CSN, CISN---the California Integrated Seismic Network, a network consisting of high-quality seismometers deployed carefully by professionals in the CISN organization and spread across Southern California---and prototypes of multi-sensor platforms that include carbon monoxide, methane, dust and radiation sensors.

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

Co-Seismic Effect of the 2011 Japan Earthquake on the Crustal Movement Observation Network of China

Directory of Open Access Journals (Sweden)

Shaomin Yang

2013-01-01

Full Text Available Great earthquakes introduce measurable co-seismic displacements over regions of hundreds and thousands of kilometers in width, which, if not accounted for, may significantly bias the long-term surface velocity field constrained by GPS observations performed during a period encompassing that event. Here, we first present an estimation of the far-field co-seismic off-sets associated with the 2011 Japan Mw 9.0 earthquake using GPS measurements from the Crustal Movement Observation Network of China (CMONOC in North China. The uncertainties of co-seismic off-set, either at cGPS stations or at campaign sites, are better than 5 - 6 mm on average. We compare three methods to constrain the co-seismic off-sets at the campaign sites in northeastern China 1 interpolating cGPS coseismic offsets, 2 estimating in terms of sparsely sampled time-series, and 3 predicting by using a well-constrained slip model. We show that the interpolation of cGPS co-seismic off-sets onto the campaign sites yield the best co-seismic off-set solution for these sites. The source model gives a consistent prediction based on finite dislocation in a layered spherical Earth, which agrees with the best prediction with discrepancies of 2 - 10 mm for 32 campaign sites. Thus, the co-seismic off-set model prediction is still a reasonable choice if a good coverage cGPS network is not available for a very active region like the Tibetan Plateau in which numerous campaign GPS sites were displaced by the recent large earthquakes.

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

International Nuclear Information System (INIS)

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

2001-01-01

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

Seismicity and seismotectonics of the Western Lake Ontario Region -relocation of the seismic events phase III

International Nuclear Information System (INIS)

Mohajer, A.A.

1995-12-01

Earthquake hazard analysis in Canada relies mainly on recorded earthquake data. The ability to record earthquakes of a given magnitude has varied considerably over time as has the accuracy of location determinations. Recomputation of earthquake locations has been suggested as a possible means of improving the existing data base for better definition of seismic sources. In this study, the locations of more than 50 small to moderate magnitude earthquakes (M≤5), in the western Lake Ontario region, were examined. Available seismograph records in the Record Centre of the National Archives of Canada were examined for events that occurred prior to 1978. The events recorded after this date showed increasing accuracy in their location determinations due to initiation and improvements of the Eastern Canada Telemetry Network (ECTN). Data compiled from the study are based on the relocated and/or selected events with the minimum travel time residuals at the Canadian and American stations. Except for a few scattered events in the south-central part of the Lake Ontario region, microearthquakes (M<3.5) cluster along or at the intersection of prominent aeromagnetic and gravity anomalies, within the Toronto-Hamilton Seismic Zone. This is indicative of certain seismotectonic relationships in this region. The depth distribution or the better located events show that a range of 5 to 20 km is dominant and, therefore, they are not near-surface stress relief phenomena. However, details of the structural manifestation of inferred seismogenic features need further ground truthing, backed by long term seismic monitoring. (author) 66 refs., 3 tabs., 6 figs

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

Science.gov (United States)

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

2018-04-01

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

Modernization of the Caltech/USGS Southern California Seismic Network

Science.gov (United States)

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

2009-12-01

performance and metadata availability. We will improve existing software to facilitate the update of metadata, and to improve the interoperability between SeisNetWatch and our database of metadata. The improved software will also be made available to other regional networks as part of the CISN software distribution. These upgrades, will greatly improve the robustness of the SCSN, and facilitate higher quality and more reliable earthquake monitoring than was available before in southern California. The modernized SCSN will contribute to more coordinated search and rescue as well as economic resilience following a major earthquake by providing accurate earthquake information, and thus facilitate rapid deployment of field crews and rapid business resumption. Further, advances in seismological research will be facilitated by the high quality seismic data that will be collected in one of the most seismically active areas in the contiguous US.

The Great Maule earthquake: seismicity prior to and after the main shock from amphibious seismic networks

Science.gov (United States)

Lieser, K.; Arroyo, I. G.; Grevemeyer, I.; Flueh, E. R.; Lange, D.; Tilmann, F. J.

2013-12-01

The Chilean subduction zone is among the seismically most active plate boundaries in the world and its coastal ranges suffer from a magnitude 8 or larger megathrust earthquake every 10-20 years. The Constitución-Concepción or Maule segment in central Chile between ~35.5°S and 37°S was considered to be a mature seismic gap, rupturing last in 1835 and being seismically quiet without any magnitude 4.5 or larger earthquakes reported in global catalogues. It is located to the north of the nucleation area of the 1960 magnitude 9.5 Valdivia earthquake and to the south of the 1928 magnitude 8 Talca earthquake. On 27 February 2010 this segment ruptured in a Mw=8.8 earthquake, nucleating near 36°S and affecting a 500-600 km long segment of the margin between 34°S and 38.5°S. Aftershocks occurred along a roughly 600 km long portion of the central Chilean margin, most of them offshore. Therefore, a network of 30 ocean-bottom-seismometers was deployed in the northern portion of the rupture area for a three month period, recording local offshore aftershocks between 20 September 2010 and 25 December 2010. In addition, data of a network consisting of 33 landstations of the GeoForschungsZentrum Potsdam were included into the network, providing an ideal coverage of both the rupture plane and areas affected by post-seismic slip as deduced from geodetic data. Aftershock locations are based on automatically detected P wave onsets and a 2.5D velocity model of the combined on- and offshore network. Aftershock seismicity analysis in the northern part of the survey area reveals a well resolved seismically active splay fault in the accretionary prism of the Chilean forearc. Our findings imply that in the northernmost part of the rupture zone, co-seismic slip most likely propagated along the splay fault and not the subduction thrust fault. In addition, the updip limit of aftershocks along the plate interface can be verified to about 40 km landwards from the deformation front. Prior to

Forecasting of Energy Expenditure of Induced Seismicity with Use of Artificial Neural Network

Science.gov (United States)

Cichy, Tomasz; Banka, Piotr

2017-12-01

tectonic faults. This parameter was not included in previous research by authors. At the output of the artificial neural network, the values of the energy density of the mining tremors [J/m3] are obtained. An example of the predicted change in seismicity induced for a highly threatened region is presented. Relatively good predicted and observed energy expenditure of tremors was obtained. The presented method can complement existing methods (analytical and geophysical) forecasting seismic hazard. This method can be used primarily in those areas where the seismic level is determined by the configuration of the edges and residues in the operating seam, as well as in adjacent seams, and to a lesser extent, the geological structure of the rock The method is local, it means that the artificial neural network prediction can only be performed for the region from which the data have been used for its originated learning. The developed method cannot be used in areas where mining is just beginning and it is not possible to predict the level of seismicity induced in areas where no mining tremors have been recorded so far.

Seismic signal auto-detecing from different features by using Convolutional Neural Network

Science.gov (United States)

Huang, Y.; Zhou, Y.; Yue, H.; Zhou, S.

2017-12-01

We try Convolutional Neural Network to detect some features of seismic data and compare their efficience. The features include whether a signal is seismic signal or noise and the arrival time of P and S phase and each feature correspond to a Convolutional Neural Network. We first use traditional STA/LTA to recongnize some events and then use templete matching to find more events as training set for the Neural Network. To make the training set more various, we add some noise to the seismic data and make some synthetic seismic data and noise. The 3-component raw signal and time-frequancy ananlyze are used as the input data for our neural network. Our Training is performed on GPUs to achieve efficient convergence. Our method improved the precision in comparison with STA/LTA and template matching. We will move to recurrent neural network to see if this kind network is better in detect P and S phase.

Background Noise of the Aldeia da Serra Region (Portugal) from a temporary broad band network

Science.gov (United States)

Wachilala, Piedade; Borges, José; Caldeira, Bento; Bezzeghoud, Mourad

2017-04-01

In this study, we analyse seismic background noise to assess the effect of noise based on the detectability of a temporary network constituted by DOCTAR (Deep Ocean Test Array), who have been deployed in a period between 2011 and 2012 in Portugal mainland, and the Évora permanent seismic station. This network is constituted by 14 digital broadband stations (14 CMG-3ESP and one STS2 sensors) with a flat response between the 60 sec to 50 Hz, 24-bit and 120s to 60Hz respectively. The temporary network was operated in continuous recording mode (three-components) in a region located in the north of the region of Évora, within a radius of about 30 km around the village of Aldeia da Serra, region in which there is an important seismic activity in the context of Portugal mainland. We calculated power spectral densities of background noise for each station/component and compare them with high-noise model and low-noise model of Peterson (1993). We consider different for day and night local and for different periods of the year. Power spectral density estimates show moderate noise levels with all stations falling within the high and low bounds of Peterson (1993). Considering the results of the noise, we estimate the detection limit of each station and consequently the detectability of the network. From this information and taking in attention the events recorded during the period of DOCTAR operation we analyse the improvement promoted by this temporary network regarding the existent seismic networks to the local seismicity study. This work was partially supported by COMPETE 2020 program (POCI-01-0145-FEDER-007690 project). We acknowledge GFZ Potsdam for providing part of the data used in this study.

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

Science.gov (United States)

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

2010-12-01

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

A procedure for seismic risk reduction in Campania Region

International Nuclear Information System (INIS)

Zuccaro, G.; Palmieri, M.; Cicalese, S.; Grassi, V.; Rauci, M.; Maggio, F.

2008-01-01

The Campania Region has set and performed a peculiar procedure in the field of seismic risk reduction. Great attention has been paid to public strategic buildings such as town halls, civil protection buildings and schools. The Ordinance 3274 promulgate in the 2004 by the Italian central authority obliged the owners of strategic buildings to perform seismic analyses within 2008 in order to check the safety of the structures and the adequacy to the use. In the procedure the Campania region, instead of the local authorities, ensure the complete drafting of seismic checks through financial resources of the Italian Government. A regional scientific technical committee has been constituted, composed of scientific experts, academics in seismic engineering. The committee has drawn up guidelines for the processing of seismic analyses. At the same time, the Region has issued a public competition to select technical seismic engineering experts to appoint seismic analysis in accordance with guidelines. The scientific committee has the option of requiring additional documents and studies in order to approve the safety checks elaborated. The Committee is supported by a technical and administrative secretariat composed of a group of expert in seismic engineering. At the moment several seismic safety checks have been completed. The results will be presented in this paper. Moreover, the policy to mitigate the seismic risk, set by Campania region, was to spend the most of the financial resources available on structural strengthening of public strategic buildings rather than in safety checks. A first set of buildings of which the response under seismic action was already known by data and studies of vulnerability previously realised, were selected for immediate retrofitting designs. Secondly, an other set of buildings were identified for structural strengthening. These were selected by using the criteria specified in the Guide Line prepared by the Scientific Committee and based on

A procedure for seismic risk reduction in Campania Region

Science.gov (United States)

Zuccaro, G.; Palmieri, M.; Maggiò, F.; Cicalese, S.; Grassi, V.; Rauci, M.

2008-07-01

The Campania Region has set and performed a peculiar procedure in the field of seismic risk reduction. Great attention has been paid to public strategic buildings such as town halls, civil protection buildings and schools. The Ordinance 3274 promulgate in the 2004 by the Italian central authority obliged the owners of strategic buildings to perform seismic analyses within 2008 in order to check the safety of the structures and the adequacy to the use. In the procedure the Campania region, instead of the local authorities, ensure the complete drafting of seismic checks through financial resources of the Italian Government. A regional scientific technical committee has been constituted, composed of scientific experts, academics in seismic engineering. The committee has drawn up guidelines for the processing of seismic analyses. At the same time, the Region has issued a public competition to select technical seismic engineering experts to appoint seismic analysis in accordance with guidelines. The scientific committee has the option of requiring additional documents and studies in order to approve the safety checks elaborated. The Committee is supported by a technical and administrative secretariat composed of a group of expert in seismic engineering. At the moment several seismic safety checks have been completed. The results will be presented in this paper. Moreover, the policy to mitigate the seismic risk, set by Campania region, was to spend the most of the financial resources available on structural strengthening of public strategic buildings rather than in safety checks. A first set of buildings of which the response under seismic action was already known by data and studies of vulnerability previously realised, were selected for immediate retrofitting designs. Secondly, an other set of buildings were identified for structural strengthening. These were selected by using the criteria specified in the Guide Line prepared by the Scientific Committee and based on

Study of Seismic Clusters at Bahía de Banderas Region, Mexico

Science.gov (United States)

Nunez-Cornu, F. J.; Rutz-Lopez, M.; Suarez-Plascencia, C.; Trejo-Gomez, E.

2010-12-01

Given that the coast in the states of Jalisco and south of the state of Nayarit is located within a region of high seismic potential and also because population is increasing, perhaps motivated by the development of tourism, the Civil Defense authorities of Jalisco and the Centro de Sismología y Volcanología de Occidente-SisVOc of Universidad de Guadalajara started in the year 2000 a joint project to study the seismic risk of the region, including the seismic monitoring of Colima volcano (located between the states of Jalisco and Colima). This work focuses on the study of seismicity in the area of Bahía de Banderas and northern coast of Jalisco. To this end, we perform an analysis of available seismograms to characterize active structures, their relationship to surface morphology, and possible reach of these structures into the shallow parts of the bay. The data used in this work are waveforms recorded during the year 2003 during which the seismograph network spanned the region of study. Our method is based on the identification of seismic clusters or families using cross-correlation of waveforms, earthquake relocation and modeling of fault planes. From an initial data set of 404 earthquakes located during 2003, 96 earthquakes could be related to 17 potentially active continental structures. A modeling of fault planes was possible for 11 of these structures. Subgroups of 7 structures are aligned parallel to the Middle America Trench, a possible consequence of oblique subduction. The magnitudes of earthquakes grouped into families is less than 3.6 (Ml), corresponding to fault dimensions of hundreds of meters.

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

Science.gov (United States)

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

2017-12-01

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

A seismic network to investigate the sedimentary hosted hydrothermal Lusi system

Science.gov (United States)

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

2016-04-01

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

Automatic Classification of volcano-seismic events based on Deep Neural Networks.

Science.gov (United States)

Titos Luzón, M.; Bueno Rodriguez, A.; Garcia Martinez, L.; Benitez, C.; Ibáñez, J. M.

2017-12-01

Seismic monitoring of active volcanoes is a popular remote sensing technique to detect seismic activity, often associated to energy exchanges between the volcano and the environment. As a result, seismographs register a wide range of volcano-seismic signals that reflect the nature and underlying physics of volcanic processes. Machine learning and signal processing techniques provide an appropriate framework to analyze such data. In this research, we propose a new classification framework for seismic events based on deep neural networks. Deep neural networks are composed by multiple processing layers, and can discover intrinsic patterns from the data itself. Internal parameters can be initialized using a greedy unsupervised pre-training stage, leading to an efficient training of fully connected architectures. We aim to determine the robustness of these architectures as classifiers of seven different types of seismic events recorded at "Volcán de Fuego" (Colima, Mexico). Two deep neural networks with different pre-training strategies are studied: stacked denoising autoencoder and deep belief networks. Results are compared to existing machine learning algorithms (SVM, Random Forest, Multilayer Perceptron). We used 5 LPC coefficients over three non-overlapping segments as training features in order to characterize temporal evolution, avoid redundancy and encode the signal, regardless of its duration. Experimental results show that deep architectures can classify seismic events with higher accuracy than classical algorithms, attaining up to 92% recognition accuracy. Pre-training initialization helps these models to detect events that occur simultaneously in time (such explosions and rockfalls), increase robustness against noisy inputs, and provide better generalization. These results demonstrate deep neural networks are robust classifiers, and can be deployed in real-environments to monitor the seismicity of restless volcanoes.

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

Science.gov (United States)

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

2007-05-01

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

A Full-Wave Seismic Tomography for the Crustal Structure in the Metropolitan Beijing Region

Science.gov (United States)

Sun, A.; Zhao, L.; Chen, Q.

2008-12-01

The greater Beijing metropolitan region is located in an old cratonic block in northeast China with complex geology and several large historic earthquakes, such as the Sanhe-Pinggu earthquake (~M8.0) in 1679, the Xingtai earthquake (M7.2) in 1966, and the Tangshan earthquake (M7.8) in 1976. To enhance our understanding of the crustal structure and the seismotectonics under this region, we conduct a full-wave three-dimensional (3D) tomographic study of this region using the waveforms recorded by the newly established Beijing metropolitan digital seismic network. Since the Beijing network was put into operation in October 2001, there have been 89 local earthquakes of magnitude 3.0 and above. From these, we selected 23 events of magnitude 3.2 and above and obtained their waveform records at 50 stations within our area of interest. The types of instruments at these stations include broadband, short-period and very broadband. First-motion focal mechanisms were determined for these events. We used a regional 3D model obtained by seismic reflection surveys as the reference model and calculated the synthetic seismograms by the finite-difference method. In this first attempt at finite- frequency tomography for the Beijing region, we focus on the variation of the P-wave speed using the first- arriving P waves. We measure the frequency-dependent traveltime anomalies of the P waves by the cross- correlation between observed and synthetic P waveforms within several discrete frequency bands between 20-sec and 5-sec periods. The sensitivity or Frechet kernels of these measurements for the perturbations in P-wave speed were computed by the same finite-difference method. We will present the preliminary result in our full-wave seismic tomography for the Beijing region.

Linkages of fracture network geometry and hydro-mechanical properties to spatio-temporal variations of seismicity in Koyna-Warna Seismic Zone

Science.gov (United States)

Selles, A.; Mikhailov, V. O.; Arora, K.; Ponomarev, A.; Gopinadh, D.; Smirnov, V.; Srinu, Y.; Satyavani, N.; Chadha, R. K.; Davulluri, S.; Rao, N. P.

2017-12-01

Well logging data and core samples from the deep boreholes in the Koyna-Warna Seismic Zone (KWSZ) provided a glimpse of the 3-D fracture network responsible for triggered earthquakes in the region. The space-time pattern of earthquakes during the last five decades show strong linkage of favourably oriented fractures system deciphered from airborne LiDAR and borehole structural logging to the seismicity. We used SAR interferometry data on surface displacements to estimate activity of the inferred faults. The failure in rocks at depths is largely governed by overlying lithostatic and pore fluid pressure in the rock matrix which are subject to change in space and time. While lithostatic pressure tends to increase with depth pore pressure is prone to fluctuations due to any change in the hydrological regime. Based on the earthquake catalogue data, the seasonal variations in seismic activity associated with annual fluctuations in the reservoir water level were analyzed over the time span of the entire history of seismological observations in this region. The regularities in the time changes in the structure of seasonal variations are revealed. An increase in pore fluid pressure can result in rock fracture and oscillating pore fluid pressures due to a reservoir loading and unloading cycles can cause iterative and cumulative damage, ultimately resulting in brittle failure under relatively low effective mean stress conditions. These regularities were verified by laboratory physical modeling. Based on our observations of main trends of spatio-temporal variations in seismicity as well as the spatial distribution of fracture network a conceptual model is presented to explain the triggered earthquakes in the KWSZ. The work was supported under the joint Russian-Indian project of the Russian Science Foundation (RSF) and the Department of Science and Technology (DST) of India (RSF project no. 16-47-02003 and DST project INT/RUS/RSF/P-13).

Waveform through the subducted plate under the Tokyo region in Japan observed by a ultra-dense seismic network (MeSO-net) and seismic activity around mega-thrust earthquakes area

Science.gov (United States)

Sakai, S.; Kasahara, K.; Nanjo, K.; Nakagawa, S.; Tsuruoka, H.; Morita, Y.; Kato, A.; Iidaka, T.; Hirata, N.; Tanada, T.; Obara, K.; Sekine, S.; Kurashimo, E.

2009-12-01

In central Japan, the Philippine Sea plate (PSP) subducts beneath the Tokyo Metropolitan area, the Kanto region, where it causes mega-thrust earthquakes, such as the 1703 Genroku earthquake (M8.0) and the 1923 Kanto earthquake (M7.9) which had 105,000 fatalities. A M7 or greater earthquake in this region at present has high potential to produce devastating loss of life and property with even greater global economic repercussions. The Central Disaster Management Council of Japan estimates the next great earthquake will cause 11,000 fatalities and 112 trillion yen (1 trillion US$) economic loss. This great earthquake is evaluated to occur with a probability of 70 % in 30 years by the Earthquake Research Committee of Japan. We had started the Special Project for Earthquake Disaster Mitigation in Tokyo Metropolitan area (2007-2012). Under this project, the construction of the Metropolitan Seismic Observation network (MeSO-net) that consists of about 400 observation sites was started [Kasahara et al., 2008; Nakagawa et al., 2008]. Now, we had 178 observation sites. The correlation of the wave is high because the observation point is deployed at about 2 km intervals, and the identification of the later phase is recognized easily thought artificial noise is very large. We also discuss the relation between a deformation of PSP and intra-plate M7+ earthquakes: the PSP is subducting beneath the Honshu arc and also colliding with the Pacific plate. The subduction and collision both contribute active seismicity in the Kanto region. We are going to present a high resolution tomographic image to show low velocity zone which suggests a possible internal failure of the plate; a source region of the M7+ intra-plate earthquake. Our study will contribute a new assessment of the seismic hazard at the Metropolitan area in Japan. Acknowledgement: This study was supported by the Earthquake Research Institute cooperative research program.

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

Energy Technology Data Exchange (ETDEWEB)

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

2005-09-15

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

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

International Nuclear Information System (INIS)

Saari, J.

2005-09-01

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

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

Management of seismic data on network

Energy Technology Data Exchange (ETDEWEB)

Chung, Bu Heung [Korea Inst. of Geology Mining and Materials, Taejon (Korea, Republic of)

1995-12-01

KIGAM has managed magnetic tapes written in seismic data acquired in Korea offshore and abroad since 1979. For now, it amounts about 13,000 tapes and other documents of seismic data are reserved by KIGAM also. For handling with them, FOX-PRO database management system has been used since 1993. In case of one user, it seems useful and convenient because the program is very easy to use and many well done utility was provided. In contrast with that, it has many problems also. For example, a user who wants to query information of these magnetic tapes must go magnetic tape room where the system is installed and he must know how to use the utilities of the FOX-PRO database management system. For the reason of above, the seismic data processing team attempted to change the FOX-PRO system with other client-server system supports networking on internet. After many testing and considering, they selected like as following hardware and software( System: PC with networking, OS: Linux and Unix, Software: Just Logic/SQL). The main reasons for selecting above system, first, any kinds of personal computer are available and easy to get. Secondly, Linux and Unix OS are good for using network. Especially, Linux is free and easy to get on many internet ftp sites. Lastly Just Logic/SQL is for client-server system, supports Linux OS and the programming style is very similar to C language. The contents of this report are as follows. In chapter 2, the Just Logic/SQL system structure and existing files through the sub-directories are showed and commented. In chapter 3, the statements using in Just Logic/SQL are explained and some examples are showed. In chapter 4, shows two example programs making seismic database including rack list, optical disk table respectively. The rack list table is the database of magnetic tapes managed by KIGAM. The optical disk table is the information record about how many, what tapes are converted to optical disk. (author). 4 tabs.

Seismic acceleration map expected for Japanese central region

International Nuclear Information System (INIS)

Sugiyama, Takeshi; Maeda, Kouji; Ishii, Kiyoshi; Suzuki, Makoto.

1990-01-01

Since electric generating and supplying facilities scatter in large areas, the seismic acceleration map, which defines the anticipated earthquake ground motions in a broad region, is very useful information for the design of those facilities against large earthquakes. This paper describes the development of a seismic acceleration map for the Central Japanese Region by incorporating the analytical results based on historical earthquake records and active fault data using probability and statistics. In the region, there have occurred several destructive earthquakes; Anseitokai (1854, M = 8.4) and Tohnankai (1944, M = 7.9) earthquakes along the Nankai trough; Nohbi (1891, M = 8.0) and Fukui (1948, M = 7.1) earthquakes in inland ares. Some of the historical earthquake data were obtained by instrument last one hundred years, whereas others by literary descriptions for nearly 1,000 years. The active fault data, have been collected mainly from the surveys of fault topography and geology, and are considered to indicate the average seismic activity for the past million years. A proposed seismic acceleration map for the return period of 75 years, calculated on the free surface of base stratum, was estimated by the following way. The analytical result based on the historical earthquake records was adopted mainly, because the Japanese seismic design criteria have been developed based on them. The proposed seismic acceleration map was revised by including the result based on the active fault data for the areas, where historical earthquake records lack, and the result was smoothed to evaluate the final seismic acceleration map. (author)

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

Science.gov (United States)

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

2012-12-01

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

Internet-Based Solutions for a Secure and Efficient Seismic Network

Science.gov (United States)

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

2017-12-01

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

Building an educational seismic network in Romanian schools

Science.gov (United States)

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

2014-05-01

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

An Investigation of Seismicity for the West Sumatra Region Indonesia

Science.gov (United States)

Syafriani, S.

2018-04-01

The purpose of this research was to investigate the seismicity of the West Sumatra region in the coordinates area of 94° E – 104° E and 2° N - 4° S. Guttenberg-Richer magnitude-frequency relation and seismic risk have been computed. Historical data of earthquakes used from year of 1970 to 2017 with magnitude higher than 4. The study area was divided into 8 sub-regions based on seismotectonic characteristics, plate tectonic and geological models. The determination of seismotectonic characteristics was based on the level of seismic activity in a region (a value) and rock stress condition (b value). High a value was associated with high seismic activity, whereas high b values were associated with low stress rock conditions, and vice versa. Based on the calculation results, a and b values were obtained in the interval of 5.5-11.3 and 0.7-2. The highest b value was obtained in the sub region 5 (Nias islands), while the lowest b value was obtained in sub region 7 (the Mentawai islands). The sub region 7, Mentawai Islands was indicated as the seismic risk potential areas.

A preliminary regional assessment of earthquake-induced landslide susceptibility for Vrancea Seismic Region

Science.gov (United States)

Micu, Mihai; Balteanu, Dan; Ionescu, Constantin; Havenith, Hans; Radulian, Mircea; van Westen, Cees; Damen, Michiel; Jurchescu, Marta

2015-04-01

In seismically-active regions, earthquakes may trigger landslides enhancing the short-to-long term slope denudation and sediment delivery and conditioning the general landscape evolution. Co-seismic slope failures present in general a low frequency - high magnitude pattern which should be addressed accordingly by landslide hazard assessment, with respect to the generally more frequent precipitation-triggered landslides. The Vrancea Seismic Region, corresponding to the curvature sector of the Eastern Romanian Carpathians, represents the most active sub-crustal (focal depth > 50 km) earthquake province of Europe. It represents the main seismic energy source throughout Romania with significant transboundary effects recorded as far as Ukraine and Bulgaria. During the last 300 years, the region featured 14 earthquakes with M>7, among which seven events with magnitude above 7.5 and three between 7.7 and 7.9. Apart from the direct damages, the Vrancea earthquakes are also responsible for causing numerous other geohazards, such as ground fracturing, groundwater level disturbances and possible deep-seated landslide occurrences (rock slumps, rock-block slides, rock falls, rock avalanches). The older deep-seated landslides (assumed to have been) triggered by earthquakes usually affect the entire slope profile. They often formed landslide dams strongly influencing the river morphology and representing potential threats (through flash-floods) in case of lake outburst. Despite the large potential of this research issue, the correlation between the region's seismotectonic context and landslide predisposing factors has not yet been entirely understood. Presently, there is a lack of information provided by the geohazards databases of Vrancea that does not allow us to outline the seismic influence on the triggering of slope failures in this region. We only know that the morphology of numerous large, deep-seated and dormant landslides (which can possibly be reactivated in future

GeoNetGIS: a Geodetic Network Geographical Information System to manage GPS networks in seismic and volcanic areas

Science.gov (United States)

Cristofoletti, P.; Esposito, A.; Anzidei, M.

2003-04-01

This paper presents the methodologies and issues involved in the use of GIS techniques to manage geodetic information derived from networks in seismic and volcanic areas. Organization and manipulation of different geodetical, geological and seismic database, give us a new challenge in interpretation of information that has several dimensions, including spatial and temporal variations, also the flexibility and brand range of tools available in GeoNetGIS, make it an attractive platform for earthquake risk assessment. During the last decade the use of geodetic networks based on the Global Positioning System, devoted to geophysical applications, especially for crustal deformation monitoring in seismic and volcanic areas, increased dramatically. The large amount of data provided by these networks, combined with different and independent observations, such as epicentre distribution of recent and historical earthquakes, geological and structural data, photo interpretation of aerial and satellite images, can aid for the detection and parameterization of seismogenic sources. In particular we applied our geodetic oriented GIS to a new GPS network recently set up and surveyed in the Central Apennine region: the CA-GeoNet. GeoNetGIS is designed to analyze in three and four dimensions GPS sources and to improve crustal deformation analysis and interpretation related with tectonic structures and seismicity. It manages many database (DBMS) consisting of different classes, such as Geodesy, Topography, Seismicity, Geology, Geography and Raster Images, administrated according to Thematic Layers. GeoNetGIS represents a powerful research tool allowing to join the analysis of all data layers to integrate the different data base which aid for the identification of the activity of known faults or structures and suggesting the new evidences of active tectonics. A new approach to data integration given by GeoNetGIS capabilities, allow us to create and deliver a wide range of maps, digital

Investigating subduction reversal in Papua New Guinea from automatic analysis of seismicity recorded on a temporary local network

Science.gov (United States)

Hicks, S. P.; Harmon, N.; Rychert, C.; Tharimena, S.; Bogiatzis, P.; Savage, B.; Shen, Y.; Baillard, C.

2017-12-01

The area of Papua New Guinea is one of the most seismically active regions on the planet. Seismicity in the region results from oblique convergence between the Pacific and India-Australia plates, with deformation occurring across a broad region involving several microplates. The region gives an excellent natural laboratory to test geodynamic models of subduction polarity reversal, microplate interaction, and to delineate the structure of subducting plates and relic structures at depth. However, a lack of permanent seismic stations means that routine earthquake locations for small to intermediate sized earthquakes have significant location errors. In 2014, we deployed a temporary network of eight broadband stations on islands in eastern Papua New Guinea to record ongoing seismic deformation. The network straddles a complex region where subduction of the Solomon plate occurs to the south and possible subduction of the Ontong-Java plateau occurs to the north. The stations were installed for 27 months. During the deployment period, there were 13 M>6.5 earthquakes in the area, including M7.5 doublet events in 2015, giving a rich seismic dataset. A high-quality catalogue of local events was formed by a multi-step process. Using the scanloc module of SeisComp3, we first detect P-onsets using a STA/LTA detection. Once clusters of P onsets are found, S-wave picks are incorporated based on a pre-defined window length of maximum S-P time. Groups of onsets are then associated to events, giving us a starting catalogue of 269 events (1765 P-onsets) with minimum magnitude of M 3.5. In a second step, we refine onset times using a Kurtosis picker to improve location accuracy. To form robust hypocentral locations using an appropriate structural model for the area and to constrain crust and mantle structure in the region, we derive a minimum 1-D velocity model using the VELEST program. We use a starting model from Abers et al. (1991) and we restrict our catalogue to events with an

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

Science.gov (United States)

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

2016-01-01

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

Comparison between seismic and domestic risk in moderate seismic hazard prone region: the Grenoble City (France test site

Directory of Open Access Journals (Sweden)

F. Dunand

2012-02-01

Full Text Available France has a moderate level of seismic activity, characterized by diffuse seismicity, sometimes experiencing earthquakes of a magnitude of more than 5 in the most active zones. In this seismicity context, Grenoble is a city of major economic and social importance. However, earthquakes being rare, public authorities and the decision makers are only vaguely committed to reducing seismic risk: return periods are long and local policy makers do not have much information available. Over the past 25 yr, a large number of studies have been conducted to improve our knowledge of seismic hazard in this region. One of the decision-making concerns of Grenoble's public authorities, as managers of a large number of public buildings, is to know not only the seismic-prone regions, the variability of seismic hazard due to site effects and the city's overall vulnerability, but also the level of seismic risk and exposure for the entire city, also compared to other natural or/and domestic hazards. Our seismic risk analysis uses a probabilistic approach for regional and local hazards and the vulnerability assessment of buildings. Its applicability to Grenoble offers the advantage of being based on knowledge acquired by previous projects conducted over the years. This paper aims to compare the level of seismic risk with that of other risks and to introduce the notion of risk acceptability in order to offer guidance in the management of seismic risk. This notion of acceptability, which is now part of seismic risk consideration for existing buildings in Switzerland, is relevant in moderately seismic-prone countries like France.

The 2012 Ferrara seismic sequence: Regional crustal structure, earthquake sources, and seismic hazard

Science.gov (United States)

Malagnini, Luca; Herrmann, Robert B.; Munafò, Irene; Buttinelli, Mauro; Anselmi, Mario; Akinci, Aybige; Boschi, E.

2012-10-01

Inadequate seismic design codes can be dangerous, particularly when they underestimate the true hazard. In this study we use data from a sequence of moderate-sized earthquakes in northeast Italy to validate and test a regional wave propagation model which, in turn, is used to understand some weaknesses of the current design spectra. Our velocity model, while regionalized and somewhat ad hoc, is consistent with geophysical observations and the local geology. In the 0.02-0.1 Hz band, this model is validated by using it to calculate moment tensor solutions of 20 earthquakes (5.6 ≥ MW ≥ 3.2) in the 2012 Ferrara, Italy, seismic sequence. The seismic spectra observed for the relatively small main shock significantly exceeded the design spectra to be used in the area for critical structures. Observations and synthetics reveal that the ground motions are dominated by long-duration surface waves, which, apparently, the design codes do not adequately anticipate. In light of our results, the present seismic hazard assessment in the entire Pianura Padana, including the city of Milan, needs to be re-evaluated.

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

Science.gov (United States)

Pierotti, Lisa; Facca, Gianluca; Gherardi, Fabrizio

2015-04-01

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

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

Science.gov (United States)

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

2014-05-01

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

Relationships among seismic velocity, metamorphism, and seismic and aseismic fault slip in the Salton Sea Geothermal Field region

Science.gov (United States)

McGuire, Jeffrey J.; Lohman, Rowena B.; Catchings, Rufus D.; Rymer, Michael J.; Goldman, Mark R.

2015-01-01

The Salton Sea Geothermal Field is one of the most geothermally and seismically active areas in California and presents an opportunity to study the effect of high-temperature metamorphism on the properties of seismogenic faults. The area includes numerous active tectonic faults that have recently been imaged with active source seismic reflection and refraction. We utilize the active source surveys, along with the abundant microseismicity data from a dense borehole seismic network, to image the 3-D variations in seismic velocity in the upper 5 km of the crust. There are strong velocity variations, up to ~30%, that correlate spatially with the distribution of shallow heat flow patterns. The combination of hydrothermal circulation and high-temperature contact metamorphism has significantly altered the shallow sandstone sedimentary layers within the geothermal field to denser, more feldspathic, rock with higher P wave velocity, as is seen in the numerous exploration wells within the field. This alteration appears to have a first-order effect on the frictional stability of shallow faults. In 2005, a large earthquake swarm and deformation event occurred. Analysis of interferometric synthetic aperture radar data and earthquake relocations indicates that the shallow aseismic fault creep that occurred in 2005 was localized on the Kalin fault system that lies just outside the region of high-temperature metamorphism. In contrast, the earthquake swarm, which includes all of the M > 4 earthquakes to have occurred within the Salton Sea Geothermal Field in the last 15 years, ruptured the Main Central Fault (MCF) system that is localized in the heart of the geothermal anomaly. The background microseismicity induced by the geothermal operations is also concentrated in the high-temperature regions in the vicinity of operational wells. However, while this microseismicity occurs over a few kilometer scale region, much of it is clustered in earthquake swarms that last from

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

Science.gov (United States)

Govoni, Aladino; Margheriti, Lucia; Moretti, Milena; Lauciani, Valentino; Sensale, Gianpaolo; Bucci, Augusto; Criscuoli, Fabio

2015-04-01

The benefits of portable real-time seismic networks are several and well known. During the management of a temporary experiment from the real-time data it is possible to detect and fix rapidly problems with power supply, time synchronization, disk failures and, most important, seismic signal quality degradation due to unexpected noise sources or sensor alignment/tampering. This usually minimizes field maintenance trips and maximizes both the quantity and the quality of the acquired data. When the area of the temporary experiment is not well monitored by the local permanent network, the real-time data from the temporary experiment can be fed to the permanent network monitoring system improving greatly both the real-time hypocentral locations and the final revised bulletin. All these benefits apply also in case of seismic crises when rapid deployment stations can significantly contribute to the aftershock analysis. Nowadays data transmission using meshed radio networks or satellite systems is not a big technological problem for a permanent seismic network where each site is optimized for the device power consumption and is usually installed by properly specialized technicians that can configure transmission devices and align antennas. This is not usually practical for temporary networks and especially for rapid response networks where the installation time is the main concern. These difficulties are substantially lowered using the now widespread UMTS technology for data transmission. A small (but sometimes power hungry) properly configured device with an omnidirectional antenna must be added to the station assembly. All setups are usually configured before deployment and this allows for an easy installation also by untrained personnel. We describe here the implementation of a UMTS based portable seismic network for both temporary experiments and rapid response applications developed at INGV. The first field experimentation of this approach dates back to the 2009 L

Rock property estimates using multiple seismic attributes and neural networks; Pegasus Field, West Texas

Energy Technology Data Exchange (ETDEWEB)

Schuelke, J.S.; Quirein, J.A.; Sarg, J.F.

1998-12-31

This case study shows the benefit of using multiple seismic trace attributes and the pattern recognition capabilities of neural networks to predict reservoir architecture and porosity distribution in the Pegasus Field, West Texas. The study used the power of neural networks to integrate geologic, borehole and seismic data. Illustrated are the improvements between the new neural network approach and the more traditional method of seismic trace inversion for porosity estimation. Comprehensive statistical methods and interpretational/subjective measures are used in the prediction of porosity from seismic attributes. A 3-D volume of seismic derived porosity estimates for the Devonian reservoir provide a very detailed estimate of porosity, both spatially and vertically, for the field. The additional reservoir porosity detail provided, between the well control, allows for optimal placement of horizontal wells and improved field development. 6 refs., 2 figs.

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

Science.gov (United States)

Vergne, Jerome; Blachet, Antoine; Lehujeur, Maximilien

2015-04-01

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

The Community Seismic Network: Enabling Observations Through Citizen Science Participation

Science.gov (United States)

Kohler, M. D.; Clayton, R. W.; Heaton, T. H.; Bunn, J.; Guy, R.; Massari, A.; Chandy, K. M.

2017-12-01

possible with traditional, regional seismic networks. The JPL experiment in particular represents a miniature prototype for city-wide earthquake monitoring that combines free-field measurements for ground shaking intensities, with mid-rise building response through advanced fragility curve computations.

RMT focal plane sensitivity to seismic network geometry and faulting style

Science.gov (United States)

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

2016-01-01

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

Recent achievements of the neo-deterministic seismic hazard assessment in the CEI region

International Nuclear Information System (INIS)

Panza, G.F.; Vaccari, F.; Kouteva, M.

2008-03-01

A review of the recent achievements of the innovative neo-deterministic approach for seismic hazard assessment through realistic earthquake scenarios has been performed. The procedure provides strong ground motion parameters for the purpose of earthquake engineering, based on the deterministic seismic wave propagation modelling at different scales - regional, national and metropolitan. The main advantage of this neo-deterministic procedure is the simultaneous treatment of the contribution of the earthquake source and seismic wave propagation media to the strong motion at the target site/region, as required by basic physical principles. The neo-deterministic seismic microzonation procedure has been successfully applied to numerous metropolitan areas all over the world in the framework of several international projects. In this study some examples focused on CEI region concerning both regional seismic hazard assessment and seismic microzonation of the selected metropolitan areas are shown. (author)

Pre-, Co-, and Post-Seismic Fault Slip in the Northern Chile Seismic Gap Associated with the April 1, 2014 (Mw 8.2) Pisagua Earthquake.

Science.gov (United States)

Simons, M.; Duputel, Z.; Fielding, E. J.; Galetzka, J.; Genrich, J. F.; Jiang, J.; Jolivet, R.; Kanamori, H.; Moore, A. W.; Ortega Culaciati, F. H.; Owen, S. E.; Riel, B. V.; Rivera, L. A.; Carrizo, D.; Cotte, N.; Jara, J.; Klotz, J.; Norabuena, E. O.; Ortega, I.; Socquet, A.; Samsonov, S. V.; Valderas Bermejo, M.

2014-12-01

The April 1, 2014 (Mw 8.2) Pisagua Earthquake occurred in Northern Chile, within a long recognized seismic gap in the Central Andean region that last experienced major megathrust events in 1868 and 1877. We built a continuous GPS network starting in 2005, with the ultimate goal of understanding the kinematics and dynamics of this portion of the subduction zone. Using observations from this network, as well as others in the region, combined with InSAR, seismic and tsunami observations, we obtain estimates of inter-seismic, co-seismic and initial post-seismic fault slip using an internally consistent Bayesian unregularized approach. We evaluate the extent of spatial overlap between regions of fault slip during this different time periods. Of particular interest to this event is the extent and nature of any geodetic evidence for transient slow fault slip preceding the Pisagua Earthquake mainshock. To this end, we compare daily and high rate GPS solutions, the former of which shows long period transient motion started about 15 days before the mainshock and with maximum registered amplitude of 14.2 +/- 2 [mm] at site PSGA. Contrary to published findings, we find that pre-seismic deformation seen by the GPS network can be explained as coseismic motion associated with the multiple foreshocks.

Third Quarter Hanford Seismic Report for Fiscal Year 2000

Energy Technology Data Exchange (ETDEWEB)

DC Hartshorn; SP Reidel; AC Rohay

2000-09-01

Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the U.S. Department of Energy and its con-tractors. Hanford Seismic Monitoring also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (E WRN) consist of 42 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. The HSN uses 21 sites and the EWRN uses 36 sites; both networks share 16 sites. The networks have 46 combined data channels because Gable Butte and Frenchman Hills East are three-component sites. The reconfiguration of the telemetry and recording systems was completed during the first quarter. All leased telephone lines have been eliminated and radio telemetry is now used exclusively. For the HSN, there were 818 triggers on two parallel detection and recording systems during the third quarter of fiscal year (FY) 2000. Thirteen seismic events were located by the Hanford Seismic Network within the reporting region of 46-47{degree} N latitude and 119-120{degree} W longitude; 7 were earthquakes in the Columbia River Basalt Group, 1 was an earthquake in the pre-basalt sediments, and 5 were earthquakes in the crystalline basement. Three earthquakes occurred in known swarm areas, and 10 earthquakes were random occurrences. No earthquakes triggered the Hanford Strong Motion Accelerometers during the third quarter of FY 2000.

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...

Propagation of Regional Seismic Phases in Western Europe

Science.gov (United States)

1991-03-08

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

Seismic hazard analysis of Sinop province, Turkey using ...

Indian Academy of Sciences (India)

1997-01-11

Jan 11, 1997 ... 2008 in the Sinop province of Turkey this study presents a seismic hazard analysis based on ... Considering the development and improvement ... It is one of the most populated cities in the coun- ... done as reliably as the seismic hazard of region per- .... Seismic safety work of underground networks was.

Pennsylvania seismic monitoring network and related tectonic studies

International Nuclear Information System (INIS)

Alexander, S.S.

1991-06-01

This report summarizes the results of the operation of the Pennsylvania Seismic Monitoring Network during the interval May 1, 1983--March 31, 1985 to monitor seismic activity in Pennsylvania and surrounding areas, to characterize the earthquake activity in terms of controlling tectonic structures and related tectonic stress conditions in the crust, and to obtain improved crustal velocity models for hypocentral determinations. Most of the earthquake activity was concentrated in the Lancaster, PA area. The magnitude 4.2 mainshock that occurred there on April 23, 1984 was the largest ever recorded instrumentally and its intensity of VI places it among the largest in the historic record for that area. Other activity during the monitoring interval of this report was confined to eastern Pennsylvania. The very large number of quarry explosions that occur regularly in Pennsylvania account for most of the seismic events recorded and they provide important crustal velocity data that are needed to obtain accurate hypocenter estimates. In general the earthquakes that occurred are located in areas of past historic seismicity. Block-tectonic structures resulting from pre-Ordovician tectonic displacements appear to influence the distribution of contemporary seismicity in Pennsylvania and surrounding areas. 17 refs., 5 figs

Indication to distinguish the burst region of coal gas from seismic data

Energy Technology Data Exchange (ETDEWEB)

Jian-yuan Cheng; Hong-wei Tang; Lin Xu; Yan-fang Li [China Coal Research Institute, Xi' an (China). Xi' an Research Institute

2009-09-15

The velocity of an over-burst coal seam is about 1/3 compared to a normal coal seam based on laboratory test results. This can be considered as a basis to confirm the area of coal and gas burst by seismic exploration technique. Similarly, the simulation result of the theoretical seismic model shows that there is obvious distinction between over-burst coal and normal coal based on the coal reflection's travel-time, energy and frequency. The results from the actual seismic data acquired in the coal and gas over-burst cases is consistent with that of the laboratory and seismic modeling; that is, in the coal and gas burst region, seismic reflection travel time is delayed, seismic amplitude is weakened and seismic frequency is reduced. Therefore, it can be concluded that seismic exploration technique is promising for use in distinguishing coal and gas over-burst regions based on the variation of seismic reflection travel time, amplitude and frequency. 7 refs., 6 figs.

A Comparison of the Crustal Deformation Predicted by Glacial Isostatic Adjustment to Seismicity in the Baffin Region of Northern Canada

Science.gov (United States)

James, T. S.; Schamehorn, T.; Bent, A. L.; Allen, T. I.; Mulder, T.; Simon, K.

2016-12-01

The horizontal crustal strain-rates induced by glacial isostatic adjustment (GIA) in northern Canada and western Greenland region are compared to the spatial pattern of seismicity. For the comparison, an updated seismicity catalogue was created from the 2010 version of the NRCan Seismic Hazard Earthquake Epicentre File (SHEEF2010) catalogue and the Greenland Ice Sheet Monitoring Network (GLISN) catalogue of the Geological Survey of Denmark and Greenland (GEUS). Crustal motion rates were computed with the Innu/Laur16 ice-sheet history and the VM5a viscosity profile (Simon et al., 2015; 2016). This GIA model optimizes the fit to relative sea-level and vertical crustal motion measurements around Hudson Bay and in the Canadian Arctic Archipelago (CAA). A region in Baffin Bay with historically high seismicity, including the 1933 M 7.4 and the 1934 and 1945 M 6.5 earthquakes, features high predicted GIA strain-rates. Elsewhere, agreement is not strong, with zones of seismicity occurring where predicted horizontal crustal strain-rates are small and large crustal strain-rates predicted where earthquake occurrence is muted. For example, large compressional crustal strain-rates are predicted beneath seismically quiescent portions of the Greenland ice sheet. Similarly, large predicted extensional strain-rates occur around southern Hudson Bay and the Foxe Basin, which are also regions of relative seismic quiescence. Additional factors to be considered include the orientation of the background stress field, relative to the predicted stress changes, and potential pre-existing zones of lithospheric weakness.

Third Quarter Hanford Seismic Report for Fiscal Year 2005

Energy Technology Data Exchange (ETDEWEB)

Reidel, Steve P.; Rohay, Alan C.; Hartshorn, Donald C.; Clayton, Ray E.; Sweeney, Mark D.

2005-09-01

Hanford Seismic Monitoring 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. Hanford Seismic Monitoring also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The Hanford Seismic Network and the Eastern Washington Regional Network consist of 41 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. For the Hanford Seismic Network, there were 337 triggers during the third quarter of fiscal year 2005. Of these triggers, 20 were earthquakes within the Hanford Seismic Network. The largest earthquake within the Hanford Seismic Network was a magnitude 1.3 event May 25 near Vantage, Washington. During the third quarter, stratigraphically 17 (85%) events occurred in the Columbia River basalt (approximately 0-5 km), no events in the pre-basalt sediments (approximately 5-10 km), and three (15%) in the crystalline basement (approximately 10-25 km). During the first quarter, geographically five (20%) earthquakes occurred in swarm areas, 10 (50%) earthquakes were associated with a major geologic structure, and 5 (25%) were classified as random events.

Global regionalized seismicity in view of Non-Extensive Statistical Physics

Science.gov (United States)

Chochlaki, Kalliopi; Vallianatos, Filippos; Michas, Georgios

2018-03-01

In the present work we study the distribution of Earth's shallow seismicity on different seismic zones, as occurred from 1981 to 2011 and extracted from the Centroid Moment Tensor (CMT) catalog. Our analysis is based on the subdivision of the Earth's surface into seismic zones that are homogeneous with regards to seismic activity and orientation of the predominant stress field. For this, we use the Flinn-Engdahl regionalization (FE) (Flinn and Engdahl, 1965), which consists of fifty seismic zones as modified by Lombardi and Marzocchi (2007). The latter authors grouped the 50 FE zones into larger tectonically homogeneous ones, utilizing the cumulative moment tensor method, resulting into thirty-nine seismic zones. In each one of these seismic zones we study the distribution of seismicity in terms of the frequency-magnitude distribution and the inter-event time distribution between successive earthquakes, a task that is essential for hazard assessments and to better understand the global and regional geodynamics. In our analysis we use non-extensive statistical physics (NESP), which seems to be one of the most adequate and promising methodological tools for analyzing complex systems, such as the Earth's seismicity, introducing the q-exponential formulation as the expression of probability distribution function that maximizes the Sq entropy as defined by Tsallis, (1988). The qE parameter is significantly greater than one for all the seismic regions analyzed with value range from 1.294 to 1.504, indicating that magnitude correlations are particularly strong. Furthermore, the qT parameter shows some temporal correlations but variations with cut-off magnitude show greater temporal correlations when the smaller magnitude earthquakes are included. The qT for earthquakes with magnitude greater than 5 takes values from 1.043 to 1.353 and as we increase the cut-off magnitude to 5.5 and 6 the qT value ranges from 1.001 to 1.242 and from 1.001 to 1.181 respectively, presenting

Nonlinear time series modeling and forecasting the seismic data of the Hindu Kush region

Science.gov (United States)

Khan, Muhammad Yousaf; Mittnik, Stefan

2018-01-01

In this study, we extended the application of linear and nonlinear time models in the field of earthquake seismology and examined the out-of-sample forecast accuracy of linear Autoregressive (AR), Autoregressive Conditional Duration (ACD), Self-Exciting Threshold Autoregressive (SETAR), Threshold Autoregressive (TAR), Logistic Smooth Transition Autoregressive (LSTAR), Additive Autoregressive (AAR), and Artificial Neural Network (ANN) models for seismic data of the Hindu Kush region. We also extended the previous studies by using Vector Autoregressive (VAR) and Threshold Vector Autoregressive (TVAR) models and compared their forecasting accuracy with linear AR model. Unlike previous studies that typically consider the threshold model specifications by using internal threshold variable, we specified these models with external transition variables and compared their out-of-sample forecasting performance with the linear benchmark AR model. The modeling results show that time series models used in the present study are capable of capturing the dynamic structure present in the seismic data. The point forecast results indicate that the AR model generally outperforms the nonlinear models. However, in some cases, threshold models with external threshold variables specification produce more accurate forecasts, indicating that specification of threshold time series models is of crucial importance. For raw seismic data, the ACD model does not show an improved out-of-sample forecasting performance over the linear AR model. The results indicate that the AR model is the best forecasting device to model and forecast the raw seismic data of the Hindu Kush region.

Urban MEMS based seismic network for post-earthquakes rapid disaster assessment

Science.gov (United States)

D'Alessandro, Antonino; Luzio, Dario; D'Anna, Giuseppe

2014-05-01

Life losses following disastrous earthquake depends mainly by the building vulnerability, intensity of shaking and timeliness of rescue operations. In recent decades, the increase in population and industrial density has significantly increased the exposure to earthquakes of urban areas. The potential impact of a strong earthquake on a town center can be reduced by timely and correct actions of the emergency management centers. A real time urban seismic network can drastically reduce casualties immediately following a strong earthquake, by timely providing information about the distribution of the ground shaking level. Emergency management centers, with functions in the immediate post-earthquake period, could be use this information to allocate and prioritize resources to minimize loss of human life. However, due to the high charges of the seismological instrumentation, the realization of an urban seismic network, which may allow reducing the rate of fatalities, has not been achieved. Recent technological developments in MEMS (Micro Electro-Mechanical Systems) technology could allow today the realization of a high-density urban seismic network for post-earthquakes rapid disaster assessment, suitable for the earthquake effects mitigation. In the 1990s, MEMS accelerometers revolutionized the automotive-airbag system industry and are today widely used in laptops, games controllers and mobile phones. Due to their great commercial successes, the research into and development of MEMS accelerometers are actively pursued around the world. Nowadays, the sensitivity and dynamics of these sensors are such to allow accurate recording of earthquakes with moderate to strong magnitude. Due to their low cost and small size, the MEMS accelerometers may be employed for the realization of high-density seismic networks. The MEMS accelerometers could be installed inside sensitive places (high vulnerability and exposure), such as schools, hospitals, public buildings and places of

Source-Type Identification Analysis Using Regional Seismic Moment Tensors

Science.gov (United States)

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

2012-12-01

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

Seismological investigation of earthquakes in the New Madrid Seismic Zone

International Nuclear Information System (INIS)

Herrmann, R.B.; Nguyen, B.

1993-08-01

Earthquake activity in the New Madrid Seismic Zone had been monitored by regional seismic networks since 1975. During this time period, over 3,700 earthquakes have been located within the region bounded by latitudes 35 degrees--39 degrees N and longitudes 87 degrees--92 degrees W. Most of these earthquakes occur within a 1.5 degrees x 2 degrees zone centered on the Missouri Bootheel. Source parameters of larger earthquakes in the zone and in eastern North America are determined using surface-wave spectral amplitudes and broadband waveforms for the purpose of determining the focal mechanism, source depth and seismic moment. Waveform modeling of broadband data is shown to be a powerful tool in defining these source parameters when used complementary with regional seismic network data, and in addition, in verifying the correctness of previously published focal mechanism solutions

Seismic hazard assessment in the Ibero-Maghreb region

Energy Technology Data Exchange (ETDEWEB)

Jimenez, M.J.; Garcia fernandez, M. [Consejo Superior de Investigaciones Cientifcas, Barcelona (Spain). Inst. of Earth Sciences; GSAHP Ibero-Maghreb Working Group

1999-12-01

The paper illustrates the contribution of the Ibero-Maghreb region to the global GSHAP (Global Seismic Hazard Assessment Program) map: for the first time, a map of regional hazard source zones is presented and agreement on a common procedure for hazard computation in the region has been achieved.

Studies Of Infrasonic Propagation Using Dense Seismic Networks

Science.gov (United States)

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

2011-12-01

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

Seismic Hazard and risk assessment for Romania -Bulgaria cross-border region

Science.gov (United States)

Simeonova, Stela; Solakov, Dimcho; Alexandrova, Irena; Vaseva, Elena; Trifonova, Petya; Raykova, Plamena

2016-04-01

Among the many kinds of natural and man-made disasters, earthquakes dominate with regard to their social and economical impact on the urban environment. Global seismic hazard and vulnerability to earthquakes are steadily increasing as urbanization and development occupy more areas that are prone to effects of strong earthquakes. The assessment of the seismic hazard and risk is particularly important, because it provides valuable information for seismic safety and disaster mitigation, and it supports decision making for the benefit of society. Romania and Bulgaria, situated in the Balkan Region as a part of the Alpine-Himalayan seismic belt, are characterized by high seismicity, and are exposed to a high seismic risk. Over the centuries, both countries have experienced strong earthquakes. The cross-border region encompassing the northern Bulgaria and southern Romania is a territory prone to effects of strong earthquakes. The area is significantly affected by earthquakes occurred in both countries, on the one hand the events generated by the Vrancea intermediate-depth seismic source in Romania, and on the other hand by the crustal seismicity originated in the seismic sources: Shabla (SHB), Dulovo, Gorna Orjahovitza (GO) in Bulgaria. The Vrancea seismogenic zone of Romania is a very peculiar seismic source, often described as unique in the world, and it represents a major concern for most of the northern part of Bulgaria as well. In the present study the seismic hazard for Romania-Bulgaria cross-border region on the basis of integrated basic geo-datasets is assessed. The hazard results are obtained by applying two alternative approaches - probabilistic and deterministic. The MSK64 intensity (MSK64 scale is practically equal to the new EMS98) is used as output parameter for the hazard maps. We prefer to use here the macroseismic intensity instead of PGA, because it is directly related to the degree of damages and, moreover, the epicentral intensity is the original

Moment-ration imaging of seismic regions for earthquake prediction

Science.gov (United States)

Lomnitz, Cinna

1993-10-01

An algorithm for predicting large earthquakes is proposed. The reciprocal ratio (mri) of the residual seismic moment to the total moment release in a region is used for imaging seismic moment precursors. Peaks in mri predict recent major earthquakes, including the 1985 Michoacan, 1985 central Chile, and 1992 Eureka, California earthquakes.

Seismic and Tectonic Regionalization of the State of Michoacan.

Science.gov (United States)

Vazquez Rosas, R.; Aguirre, J.; Garduño-Monroy, V. H.; Ramirez-Guzman, L.

2017-12-01

In Mexico it is a country with seismically active regions, mainly the zones that are next to the pacific where the zone of subduction is located, in this work we focus on the state of Michoacán, since this has not been completely studied in the last 30 years after the earthquake in Michoacán in 1985. The first most important step is to know the region which are the most seismic zones within the state and one way is to carry out the regionalization of Michoacán identifying the sources of earthquakes as well as where occur more frequently.If we could know each of the factors that influence seismicity and describe every point of the terrain, every rupture, every rock, etc., then we could describe in an analytical way the seismic process and predict the occurrence of earthquakes such as eclipses. Unfortunately the number of parameters is so enormous that we cannot arrive at an exact description; however, we can take advantage of statistical properties to evaluate probabilities, even in the case of small systems such as a particular seismic zone.In this paper, epicenter data were collected from 1970 to 2014, and with them a statistical study was carried out and the epicenter data plotted using data reported by the National Seismological Service and the IRIS catalog as well as some data from the Institute of engineering UNAM. Where earthquakes of equal and greater than M = 4 were used. Graphing these in function with the depth and with that it was graficaron and was made an overlapping the faults of the state and with that it was divided in 4 seismic zones in function of the faults and the localized seismicity.Zone A. is located within the Michoacán Block set of faults, as well as part of the subduction zone on the coast of the state. Seismicity in this area is high. Zone B-1. This is located between the limits of Jalisco and Michoacán in the set of faults called Tepalcatepec depression and limits with the Jorullo-Tacámbaro fracture. At this site seismicity is

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

Science.gov (United States)

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

2016-04-01

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

An assessment of seismic monitoring in the United States; requirement for an Advanced National Seismic System

Science.gov (United States)

,

1999-01-01

This report assesses the status, needs, and associated costs of seismic monitoring in the United States. It sets down the requirement for an effective, national seismic monitoring strategy and an advanced system linking national, regional, and urban monitoring networks. Modernized seismic monitoring can provide alerts of imminent strong earthquake shaking; rapid assessment of distribution and severity of earthquake shaking (for use in emergency response); warnings of a possible tsunami from an offshore earthquake; warnings of volcanic eruptions; information for correctly characterizing earthquake hazards and for improving building codes; and data on response of buildings and structures during earthquakes, for safe, cost-effective design, engineering, and construction practices in earthquake-prone regions.

LLNL's Regional Seismic Discrimination Research

International Nuclear Information System (INIS)

Hanley, W; Mayeda, K; Myers, S; Pasyanos, M; Rodgers, A; Sicherman, A; Walter, W

1999-01-01

As part of the Department of Energy's research and development effort to improve the monitoring capability of the planned Comprehensive Nuclear-Test-Ban Treaty international monitoring system, Lawrence Livermore Laboratory (LLNL) is testing and calibrating regional seismic discrimination algorithms in the Middle East, North Africa and Western Former Soviet Union. The calibration process consists of a number of steps: (1) populating the database with independently identified regional events; (2) developing regional boundaries and pre-identifying severe regional phase blockage zones; (3) measuring and calibrating coda based magnitude scales; (4a) measuring regional amplitudes and making magnitude and distance amplitude corrections (MDAC); (4b) applying the DOE modified kriging methodology to MDAC results using the regionalized background model; (5) determining the thresholds of detectability of regional phases as a function of phase type and frequency; (6) evaluating regional phase discriminant performance both singly and in combination; (7) combining steps 1-6 to create a calibrated discrimination surface for each stations; (8) assessing progress and iterating. We have now developed this calibration procedure to the point where it is fairly straightforward to apply earthquake-explosion discrimination in regions with ample empirical data. Several of the steps outlined above are discussed in greater detail in other DOE papers in this volume or in recent publications. Here we emphasize the results of the above process: station correction surfaces and their improvement to discrimination results compared with simpler calibration methods. Some of the outstanding discrimination research issues involve cases in which there is little or no empirical data. For example in many cases there is no regional nuclear explosion data at IMS stations or nearby surrogates. We have taken two approaches to this problem, first finding and using mining explosion data when available, and

Second Quarter Hanford Seismic Report for Fiscal Year 2000

International Nuclear Information System (INIS)

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

2000-01-01

Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the US Department of Energy and its contractors. Hanford Seismic Monitoring also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (EWRN) consist of 42 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. The HSN uses 21 sites and the EWRN uses 36 sites; both networks share 16 sites. The networks have 46 combined data channels because Gable Butte and Frenchman Hills East are three-component sites. The reconfiguration of the telemetry and recording systems was completed during the first quarter. All leased telephone lines have been eliminated and radio telemetry is now used exclusively. For the HSN, there were 506 triggers on two parallel detection and recording systems during the second quarter of fiscal year (FY) 2000. Twenty-seven seismic events were located by the Hanford Seismic Network within the reporting region of 46--47degree N latitude and 119--120degree W longitude; 12 were earthquakes in the Columbia River Basalt Group, 2 were earthquakes in the pre-basalt sediments, 9 were earthquakes in the crystalline basement, and 5 were quarry blasts. Three earthquakes appear to be related to geologic structures, eleven earthquakes occurred in known swarm areas, and seven earthquakes were random occurrences. No earthquakes triggered the Hanford Strong Motion

Second Quarter Hanford Seismic Report for Fiscal Year 2000

Energy Technology Data Exchange (ETDEWEB)

DC Hartshorn; SP Reidel; AC Rohay

2000-07-17

Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the US Department of Energy and its contractors. Hanford Seismic Monitoring also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (EWRN) consist of 42 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. The HSN uses 21 sites and the EWRN uses 36 sites; both networks share 16 sites. The networks have 46 combined data channels because Gable Butte and Frenchman Hills East are three-component sites. The reconfiguration of the telemetry and recording systems was completed during the first quarter. All leased telephone lines have been eliminated and radio telemetry is now used exclusively. For the HSN, there were 506 triggers on two parallel detection and recording systems during the second quarter of fiscal year (FY) 2000. Twenty-seven seismic events were located by the Hanford Seismic Network within the reporting region of 46--47{degree} N latitude and 119--120{degree} W longitude; 12 were earthquakes in the Columbia River Basalt Group, 2 were earthquakes in the pre-basalt sediments, 9 were earthquakes in the crystalline basement, and 5 were quarry blasts. Three earthquakes appear to be related to geologic structures, eleven earthquakes occurred in known swarm areas, and seven earthquakes were random occurrences. No earthquakes triggered the Hanford Strong Motion

First quarter Hanford seismic report for fiscal year 2000

Energy Technology Data Exchange (ETDEWEB)

DC Hartshorn; SP Reidel; AC Rohay

2000-02-23

Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the US Department of Energy and its contractors. Hanford Seismic Monitoring also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (EWRN) consist of 42 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. The HSN uses 21 sites and the EW uses 36 sites; both networks share 16 sites. The networks have 46 combined data channels because Gable Butte and Frenchman Hills East are three-component sites. The reconfiguration of the telemetry and recording systems was completed during the first quarter. All leased telephone lines have been eliminated and radio telemetry is now used exclusively. For the HSN, there were 311 triggers on two parallel detection and recording systems during the first quarter of fiscal year (FY) 2000. Twelve seismic events were located by the Hanford Seismic Network within the reporting region of 46--47{degree}N latitude and 119--120{degree}W longitude; 2 were earthquakes in the Columbia River Basalt Group, 3 were earthquakes in the pre-basalt sediments, 9 were earthquakes in the crystalline basement, and 1 was a quarry blast. Two earthquakes appear to be related to a major geologic structure, no earthquakes occurred in known swarm areas, and 9 earthquakes were random occurrences. No earthquakes triggered the Hanford Strong Motion Accelerometers

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

NARCIS (Netherlands)

Panou, Areti; Paulssen, Hanneke; Hatzidimitriou, Panagiotis

2015-01-01

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

Southern California Seismic Network: New Design and Implementation of Redundant and Reliable Real-time Data Acquisition Systems

Science.gov (United States)

Saleh, T.; Rico, H.; Solanki, K.; Hauksson, E.; Friberg, P.

2005-12-01

. Further, improved network security is an integral part of the new design. Redundant firewalls will provide secure data imports, exports, and acquisition as well as DMZ zones for web servers and other publicly available servers. We will present the detailed design of this new configuration that is currently being implemented by the SCSN at Caltech. The design principals are general enough to be of use to most regional seismic networks.

Alaska Seismic Network Upgrade and Expansion

Science.gov (United States)

Sandru, J. M.; Hansen, R. A.; Estes, S. A.; Fowler, M.

2009-12-01

AEIC (Alaska Earthquake Information Center) has begun the task of upgrading the older regional seismic monitoring sites that have been in place for a number of years. Many of the original sites (some dating to the 1960's) are still single component analog technology. This was a very reasonable and ultra low power reliable system for its day. However with the advanced needs of today's research community, AEIC has begun upgrading to Broadband and Strong Motion Seismometers, 24 bit digitizers and high-speed two-way communications, while still trying to maintain the utmost reliability and maintaining low power consumption. Many sites have been upgraded or will be upgraded from single component to triaxial broad bands and triaxial accerometers. This provided much greater dynamic range over the older antiquated technology. The challenge is compounded by rapidly changing digital technology. Digitizersand data communications based on analog phone lines utilizing 9600 baud modems and RS232 are becoming increasingly difficult to maintain and increasingly expensive compared to current methods that use Ethernet, TCP/IP and UDP connections. Gaining a reliable Internet connection can be as easy as calling up an ISP and having a DSL connection installed or may require installing our own satellite uplink, where other options don't exist. LANs are accomplished with a variety of communications devices such as spread spectrum 900 MHz radios or VHF radios for long troublesome shots. WANs are accomplished with a much wider variety of equipment. Traditional analog phone lines are being used in some instances, however 56K lines are much more desirable. Cellular data links have become a convenient option in semiurban environments where digital cellular coverage is available. Alaska is slightly behind the curve on cellular technology due to its low population density and vast unpopulated areas but has emerged into this new technology in the last few years. Partnerships with organizations

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

Science.gov (United States)

Bergen, Karianne J.; Beroza, Gregory C.

2018-06-01

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

Seismic hazard assessment of the Hanford region, Eastern Washington State

International Nuclear Information System (INIS)

Youngs, R.R.; Coppersmith, K.J.; Power, M.S.; Swan, F.H. III

1985-01-01

A probabilistic seismic hazard assessment was made for a site within the Hanford region of eastern Washington state, which is characterized as an intraplate region having a relatively low rate of seismic activity. Probabilistic procedures, such as logic trees, were utilized to account for the uncertainties in identifying and characterizing the potential seismic sources in the region. Logic trees provide a convenient, flexible means of assessing the values and relative likelihoods of input parameters to the hazard model that may be dependent upon each other. Uncertainties accounted for in this way include the tectonic model, segmentation, capability, fault geometry, maximum earthquake magnitude, and earthquake recurrence rate. The computed hazard results are expressed as a distribution from which confidence levels are assessed. Analysis of the results show the contributions to the total hazard from various seismic sources and due to various earthquake magnitudes. In addition, the contributions of uncertainties in the various source parameters to the uncertainty in the computed hazard are assessed. For this study, the major contribution to uncertainty in the computed hazard are due to uncertainties in the applicable tectonic model and the earthquake recurrence rate. This analysis serves to illustrate some of the probabilistic tools that are available for conducting seismic hazard assessments and for analyzing the results of these studies. 5 references, 7 figures

The Canarian Seismic Monitoring Network: design, development and first result

Science.gov (United States)

D'Auria, Luca; Barrancos, José; Padilla, Germán D.; García-Hernández, Rubén; Pérez, Aaron; Pérez, Nemesio M.

2017-04-01

Tenerife is an active volcanic island which experienced several eruptions of moderate intensity in historical times, and few explosive eruptions in the Holocene. The increasing population density and the consistent number of tourists are constantly raising the volcanic risk. In June 2016 Instituto Volcanologico de Canarias started the deployment of a seismological volcano monitoring network consisting of 15 broadband seismic stations. The network began its full operativity in November 2016. The aim of the network are both volcano monitoring and scientific research. Currently data are continuously recorded and processed in real-time. Seismograms, hypocentral parameters, statistical informations about the seismicity and other data are published on a web page. We show the technical characteristics of the network and an estimate of its detection threshold and earthquake location performances. Furthermore we present other near-real time procedures on the data: analysis of the ambient noise for determining the shallow velocity model and temporal velocity variations, detection of earthquake multiplets through massive data mining of the seismograms and automatic relocation of events through double-difference location.

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

Science.gov (United States)

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

2004-12-01

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

Seismic activity in northeastern Brazill-new perspectives

Science.gov (United States)

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

2007-05-01

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

Application of neural networks to seismic active control

International Nuclear Information System (INIS)

Tang, Yu.

1995-01-01

An exploratory study on seismic active control using an artificial neural network (ANN) is presented in which a singledegree-of-freedom (SDF) structural system is controlled by a trained neural network. A feed-forward neural network and the backpropagation training method are used in the study. In backpropagation training, the learning rate is determined by ensuring the decrease of the error function at each training cycle. The training patterns for the neural net are generated randomly. Then, the trained ANN is used to compute the control force according to the control algorithm. The control strategy proposed herein is to apply the control force at every time step to destroy the build-up of the system response. The ground motions considered in the simulations are the N21E and N69W components of the Lake Hughes No. 12 record that occurred in the San Fernando Valley in California on February 9, 1971. Significant reduction of the structural response by one order of magnitude is observed. Also, it is shown that the proposed control strategy has the ability to reduce the peak that occurs during the first few cycles of the time history. These promising results assert the potential of applying ANNs to active structural control under seismic loads

Second Quarter Hanford Seismic Report for Fiscal Year 2008

Energy Technology Data Exchange (ETDEWEB)

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

2008-06-26

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 Hanford Seismic Assessment Team locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, natural phenomena hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of 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. For the Hanford Seismic Network, seven local earthquakes were recorded during the second quarter of fiscal year 2008. The largest event recorded by the network during the second quarter (February 3, 2008 - magnitude 2.3 Mc) was located northeast of Richland in Franklin County at a depth of 22.5 km. With regard to the depth distribution, two earthquakes occurred at shallow depths (less than 4 km, most likely in the Columbia River basalts), three 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 crystalline basement. Geographically, five earthquakes occurred in swarm areas and two earthquakes were classified as random events.

Seismic hazard and seismic risk assessment based on the unified scaling law for earthquakes: Himalayas and adjacent regions

Science.gov (United States)

Nekrasova, A. K.; Kossobokov, V. G.; Parvez, I. A.

2015-03-01

For the Himalayas and neighboring regions, the maps of seismic hazard and seismic risk are constructed with the use of the estimates for the parameters of the unified scaling law for earthquakes (USLE), in which the Gutenberg-Richter law for magnitude distribution of seismic events within a given area is applied in the modified version with allowance for linear dimensions of the area, namely, log N( M, L) = A + B (5 - M) + C log L, where N( M, L) is the expected annual number of the earthquakes with magnitude M in the area with linear dimension L. The spatial variations in the parameters A, B, and C for the Himalayas and adjacent regions are studied on two time intervals from 1965 to 2011 and from 1980 to 2011. The difference in A, B, and C between these two time intervals indicates that seismic activity experiences significant variations on a scale of a few decades. With a global consideration of the seismic belts of the Earth overall, the estimates of coefficient A, which determines the logarithm of the annual average frequency of the earthquakes with a magnitude of 5.0 and higher in the zone with a linear dimension of 1 degree of the Earth's meridian, differ by a factor of 30 and more and mainly fall in the interval from -1.1 to 0.5. The values of coefficient B, which describes the balance between the number of earthquakes with different magnitudes, gravitate to 0.9 and range from less than 0.6 to 1.1 and higher. The values of coefficient C, which estimates the fractal dimension of the local distribution of epicenters, vary from 0.5 to 1.4 and higher. In the Himalayas and neighboring regions, the USLE coefficients mainly fall in the intervals of -1.1 to 0.3 for A, 0.8 to 1.3 for B, and 1.0 to 1.4 for C. The calculations of the local value of the expected peak ground acceleration (PGA) from the maximal expected magnitude provided the necessary basis for mapping the seismic hazards in the studied region. When doing this, we used the local estimates of the

An Intelligent Network Proposed for Assessing Seismic Vulnerability Index of Sewerage Networks within a GIS Framework (A Case Study of Shahr-e-Kord

Directory of Open Access Journals (Sweden)

Mohamadali Rahgozar

2016-01-01

Full Text Available Due to their vast spread, sewerage networks are exposed to considerable damages during severe earthquakes, which may lead to catastrophic environmental contamination. Multiple repairs in the pipelines, including pipe and joint fractures, could be costly and time-consuming. In seismic risk management, it is of utmost importance to have an intelligent tool for assessing seismic vulnerability index at any given point in time for such important utilities as sewerage networks. This study uses a weight-factor methodology and proposes an online GIS-based intelligent algorithm to evaluate the seismic vulnerability index (VI for metropolitan sewerage networks. The proposed intelligent tool is capable of updating VI as the sewerage network conditions may change with time and at different locations. The city of Shahr-e-Kord located on the high risk seismic belt is selected for a case study to which the proposed methodology is applied for zoning the vulnerability index in GIS. Results show that the overall seismic vulnerability index for the selected study area ranges from low to medium but that it increases in the southern parts of the city, especially in the old town where brittle pipes have been laid

In-situ measurements of seismic velocities in the San Francisco Bay region...part II

Science.gov (United States)

Gibbs, James F.; Fumal, Thomas E.; Borcherdt, Roger D.

1976-01-01

Seismic wave velocities (compressional and shear) are important parameters for determining the seismic response characteristics of various geologic units when subjected to strong earthquake ground shaking. Seismic velocities of various units often show a strong correlation with the amounts of damage following large earthquakes and have been used as a basis for certain types of seismic zonation studies. Currently a program is in progress to measure seismic velocities in the San Francisco Bay region at an estimated 150 sites. At each site seismic travel times are measured in drill holes, normally at 2.5-m intervals to a depth of 30 m. Geologic logs are determined from drill hole cuttings, undisturbed samples, and penetrometer samples. The data provide a detailed comparison of geologic and seismic characteristics and provide parameters for estimating strong earthquake ground motions quantitatively at each of the site. A major emphasis of this program is to obtain a detailed comparison of geologic and seismic data on a regional scale for use in seismic zonation. The broad data base available in the San Francisco Bay region suggests using the area as a pilot area for the development of general techniques applicable to other areas.

Learnings from the Monitoring of Induced Seismicity in Western Canada over the Past Three Years

Science.gov (United States)

Yenier, E.; Moores, A. O.; Baturan, D.; Spriggs, N.

2017-12-01

In response to induced seismicity observed in western Canada, existing public networks have been densified and a number of private networks have been deployed to closely monitor the earthquakes induced by hydraulic fracturing operations in the region. These networks have produced an unprecedented volume of seismic data, which can be used to map pre-existing geological structures and understand their activation mechanisms. Here, we present insights gained over the past three years from induced seismicity monitoring (ISM) for some of the most active operators in Canada. First, we discuss the benefits of high-quality ISM data sets for making operational decisions and how their value largely depends on choice of instrumentation, seismic network design and data processing techniques. Using examples from recent research studies, we illustrate the key role of robust modeling of regional source, attenuation and site attributes on the accuracy of event magnitudes, ground motion estimates and induced seismicity hazard assessment. Finally, acknowledging that the ultimate goal of ISM networks is assisting operators to manage induced seismic risk, we share some examples of how ISM data products can be integrated into existing protocols for developing effective risk management strategies.

A transparent and data-driven global tectonic regionalization model for seismic hazard assessment

Science.gov (United States)

Chen, Yen-Shin; Weatherill, Graeme; Pagani, Marco; Cotton, Fabrice

2018-05-01

A key concept that is common to many assumptions inherent within seismic hazard assessment is that of tectonic similarity. This recognizes that certain regions of the globe may display similar geophysical characteristics, such as in the attenuation of seismic waves, the magnitude scaling properties of seismogenic sources or the seismic coupling of the lithosphere. Previous attempts at tectonic regionalization, particularly within a seismic hazard assessment context, have often been based on expert judgements; in most of these cases, the process for delineating tectonic regions is neither reproducible nor consistent from location to location. In this work, the regionalization process is implemented in a scheme that is reproducible, comprehensible from a geophysical rationale, and revisable when new relevant data are published. A spatial classification-scheme is developed based on fuzzy logic, enabling the quantification of concepts that are approximate rather than precise. Using the proposed methodology, we obtain a transparent and data-driven global tectonic regionalization model for seismic hazard applications as well as the subjective probabilities (e.g. degree of being active/degree of being cratonic) that indicate the degree to which a site belongs in a tectonic category.

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

International Nuclear Information System (INIS)

Aram, M. R.

2012-01-01

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

Centrality in earthquake multiplex networks

Science.gov (United States)

Lotfi, Nastaran; Darooneh, Amir Hossein; Rodrigues, Francisco A.

2018-06-01

Seismic time series has been mapped as a complex network, where a geographical region is divided into square cells that represent the nodes and connections are defined according to the sequence of earthquakes. In this paper, we map a seismic time series to a temporal network, described by a multiplex network, and characterize the evolution of the network structure in terms of the eigenvector centrality measure. We generalize previous works that considered the single layer representation of earthquake networks. Our results suggest that the multiplex representation captures better earthquake activity than methods based on single layer networks. We also verify that the regions with highest seismological activities in Iran and California can be identified from the network centrality analysis. The temporal modeling of seismic data provided here may open new possibilities for a better comprehension of the physics of earthquakes.

Local seismic network at the Olkiluoto site. Annual Report for 2006

International Nuclear Information System (INIS)

Saari, J.; Lakio, A.

2007-05-01

In February 2002, Posiva Oy established a local seismic network of six stations on the island of Olkiluoto. Later, in June 2004, the seismic network was expanded with two new seismic stations. At that time started the excavation of the underground characterisation facility (the ONKALO) and the basic operation procedure was changed more suitable for the demands of the new situation. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The studies include both tectonic and excavation-induced microearthquakes. An additional task of monitoring is related to safeguarding of the ONKALO. This report gives the results of microseismic monitoring during the year 2006. Also the changes in the structure and the operation procedure of the network are described. The network has operated continuously in 2006. In the beginning of 2006, the target area of the seismic monitoring expanded to semi-regional scale. Four new seismic stations started in the beginning of February 2006. At the end of the year, two new borehole geophones were installed in order to improve the sensitivity and the depth resolution of the measurements inside the ONKALO block. This report presents also new interpretations of the excavation induced earthquakes that occurred in the ONKALO in 2005. Altogether 2041 events have been located in the Olkiluoto area, in reported time period. The magnitudes of the observed events range from ML = -1.1 to ML = 3.1 (ML magnitude in local Richter's scale). Most of them are explosions. Two of the observed events are be classified as microearthquakes. Evidence of activity that would have influence on the safety of the ONKALO, have not been found. The observed earthquakes occurred in 2006 were small, ML = -0.6 and ML= -0.9. The earthquakes relate to small movements in brittle deformation zones OL-BFZ043 and OL-BFZ034 presented in the geological model of the Olkiluoto site

Monitoring of seismic events from a specific source region using a single regional array: A case study

Science.gov (United States)

Gibbons, S. J.; Kværna, T.; Ringdal, F.

2005-07-01

In the monitoring of earthquakes and nuclear explosions using a sparse worldwide network of seismic stations, it is frequently necessary to make reliable location estimates using a single seismic array. It is also desirable to screen out routine industrial explosions automatically in order that analyst resources are not wasted upon detections which can, with a high level of confidence, be associated with such a source. The Kovdor mine on the Kola Peninsula of NW Russia is the site of frequent industrial blasts which are well recorded by the ARCES regional seismic array at a distance of approximately 300 km. We describe here an automatic procedure for identifying signals which are likely to result from blasts at the Kovdor mine and, wherever possible, for obtaining single array locations for such events. Carefully calibrated processing parameters were chosen using measurements from confirmed events at the mine over a one-year period for which the operators supplied Ground Truth information. Phase arrival times are estimated using an autoregressive method and slowness and azimuth are estimated using broadband f{-} k analysis in fixed frequency bands and time-windows fixed relative to the initial P-onset time. We demonstrate the improvement to slowness estimates resulting from the use of fixed frequency bands. Events can be located using a single array if, in addition to the P-phase, at least one secondary phase is found with both an acceptable slowness estimate and valid onset-time estimate. We evaluate the on-line system over a twelve month period; every event known to have occured at the mine is detected by the process and 32 out of 53 confirmed events were located automatically. The remaining events were classified as “very likely” Kovdor events and were subsequently located by an analyst. The false alarm rate is low; only 84 very likely Kovdor events were identified during the whole of 2003 and none of these were subsequently located at a large distance from

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

Science.gov (United States)

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

2014-12-01

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

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

Science.gov (United States)

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

2012-04-01

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

The seismic project of the National Tsunami Hazard Mitigation Program

Science.gov (United States)

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

2005-01-01

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

First Quarter Hanford Seismic Report for Fiscal Year 2008

Energy Technology Data Exchange (ETDEWEB)

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

2008-03-21

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 Hanford Seismic Assessment Team locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, natural phenomena hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The Hanford Seismic Network and the Eastern Washington Regional Network consist of 41 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Assessment Team. For the Hanford Seismic Network, forty-four local earthquakes were recorded during the first quarter of fiscal year 2008. A total of thirty-one micro earthquakes were recorded within the Rattlesnake Mountain swarm area at depths in the 5-8 km range, most likely within the pre-basalt sediments. The largest event recorded by the network during the first quarter (November 25, 2007 - magnitude 1.5 Mc) was located within this swarm area at a depth of 4.3 km. With regard to the depth distribution, three earthquakes occurred at shallow depths (less than 4 km, most likely in the Columbia River basalts), thirty-six earthquakes at intermediate depths (between 4 and 9 km, most likely in the pre-basalt sediments), and five earthquakes were located at depths greater than 9 km, within the crystalline basement. Geographically, thirty-eight earthquakes occurred in swarm areas and six earth¬quakes were classified as random events.

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.

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

Science.gov (United States)

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

2015-12-01

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

Aspects regarding the use of the INFREP network for identifying possible seismic precursors

Science.gov (United States)

Dolea, Paul; Cristea, Octavian; Dascal, Paul Vladut; Moldovan, Iren-Adelina; Biagi, Pier Francesco

In the last decades, one of the main research directions in identifying seismic precursors involved monitoring VLF (Very Low Frequency) and LF (Low Frequency) radio waves and analysing their propagation characteristics. Essentially this method consists of monitoring different available VLF and LF transmitters from long distance reception points. The received signal has two major components: the ground wave and the sky wave, where the sky wave propagates by reflection on the lower layers of the ionosphere. It is assumed that before and during major earthquakes, unusual changes may occur in the lower layers of the ionosphere, such as the modification of the charged particles number density and the altitude of the reflection zone. Therefore, these unusual changes in the ionosphere may generate unusual variations in the received signal level. The International Network for Frontier Research on Earthquake Precursors (INFREP) was developed starting with 2009 and consists of several dedicated VLF and LF radio receivers used for monitoring various radio transmitters located throughout Europe. The receivers' locations were chosen so that the propagation path from these VLF/LF stations would pass over high seismicity regions while others were chosen to obtain different control paths. The monitoring receivers are capable of continuously measuring the received signal amplitude from the VLF/LF stations of interest. The recorded data is then stored and sent to an INFREP database, which is available on the Internet for scientific researchers. By processing and analysing VLF and LF data samples, collected at different reception points and at different periods of the year, one may be able to identify some distinct patterns in the envelope of the received signal level over time. Significant deviations from these patterns may have local causes such as the electromagnetic pollution at the monitoring point, regional causes like existing electrical storms over the propagation path or

Earthquake source imaging by high-resolution array analysis at regional distances: the 2010 M7 Haiti earthquake as seen by the Venezuela National Seismic Network

Science.gov (United States)

Meng, L.; Ampuero, J. P.; Rendon, H.

2010-12-01

Back projection of teleseismic waves based on array processing has become a popular technique for earthquake source imaging,in particular to track the areas of the source that generate the strongest high frequency radiation. The technique has been previously applied to study the rupture process of the Sumatra earthquake and the supershear rupture of the Kunlun earthquakes. Here we attempt to image the Haiti earthquake using the data recorded by Venezuela National Seismic Network (VNSN). The network is composed of 22 broad-band stations with an East-West oriented geometry, and is located approximately 10 degrees away from Haiti in the perpendicular direction to the Enriquillo fault strike. This is the first opportunity to exploit the privileged position of the VNSN to study large earthquake ruptures in the Caribbean region. This is also a great opportunity to explore the back projection scheme of the crustal Pn phase at regional distances,which provides unique complementary insights to the teleseismic source inversions. The challenge in the analysis of the 2010 M7.0 Haiti earthquake is its very compact source region, possibly shorter than 30km, which is below the resolution limit of standard back projection techniques based on beamforming. Results of back projection analysis using the teleseismic USarray data reveal little details of the rupture process. To overcome the classical resolution limit we explored the Multiple Signal Classification method (MUSIC), a high-resolution array processing technique based on the signal-noise orthognality in the eigen space of the data covariance, which achieves both enhanced resolution and better ability to resolve closely spaced sources. We experiment with various synthetic earthquake scenarios to test the resolution. We find that MUSIC provides at least 3 times higher resolution than beamforming. We also study the inherent bias due to the interferences of coherent Green’s functions, which leads to a potential quantification

Regional seismic lines reprocessed using post-stack processing techniques; National Petroleum Reserve, Alaska

Science.gov (United States)

Miller, John J.; Agena, W.F.; Lee, M.W.; Zihlman, F.N.; Grow, J.A.; Taylor, D.J.; Killgore, Michele; Oliver, H.L.

2000-01-01

This CD-ROM contains stacked, migrated, 2-Dimensional seismic reflection data and associated support information for 22 regional seismic lines (3,470 line-miles) recorded in the National Petroleum Reserve ? Alaska (NPRA) from 1974 through 1981. Together, these lines constitute about one-quarter of the seismic data collected as part of the Federal Government?s program to evaluate the petroleum potential of the Reserve. The regional lines, which form a grid covering the entire NPRA, were created by combining various individual lines recorded in different years using different recording parameters. These data were reprocessed by the USGS using modern, post-stack processing techniques, to create a data set suitable for interpretation on interactive seismic interpretation computer workstations. Reprocessing was done in support of ongoing petroleum resource studies by the USGS Energy Program. The CD-ROM contains the following files: 1) 22 files containing the digital seismic data in standard, SEG-Y format; 2) 1 file containing navigation data for the 22 lines in standard SEG-P1 format; 3) 22 small scale graphic images of each seismic line in Adobe Acrobat? PDF format; 4) a graphic image of the location map, generated from the navigation file, with hyperlinks to the graphic images of the seismic lines; 5) an ASCII text file with cross-reference information for relating the sequential trace numbers on each regional line to the line number and shotpoint number of the original component lines; and 6) an explanation of the processing used to create the final seismic sections (this document). The SEG-Y format seismic files and SEG-P1 format navigation file contain all the information necessary for loading the data onto a seismic interpretation workstation.

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

Science.gov (United States)

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

2016-12-01

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

An integrated geodetic and seismic study of the Cusco Fault system in the Cusco Region-Southern Peru

Science.gov (United States)

Norabuena, E. O.; Tavera, H. J.

2017-12-01

The Cusco Fault system is composed by six main faults (Zurite, Tamboray, Qoricocha, Tambomachay, Pachatusan, and Urcos) extending in a NW-SE direction over the Cusco Region in southeastern Peru. From these, the Tambomachay is a normal fault of 20 km length, strikes N120°E and bounds a basin filled with quaternary lacustrine and fluvial deposits. Given its 5 km distance to Cusco, an historical and Inca's archeological landmark, it represents a great seismic hazard for its more than 350,000 inhabitants. The Tambomachay fault as well as the other secondary faults have been a source of significant seismic activity since historical times being the more damaging ones the Cusco earthquakes of 1650, 1950 and more recently April 1986 (M 5.8). Previous geological studies indicate that at the beginning of the Quaternary the fault showed a transcurrent mechanism leading to the formation of the Cusco basin. However, nowadays its mechanism is normal fault and scarps up to 22m can be observed. We report the current dynamics of the Tambomachay fault and secondary faults based on seismic activity imaged by a network of 29 broadband stations deployed in the Cusco Region as well as the deformation field inferred from GPS survey measurements carried out between 2014 and 2016.

Monitoring of geothermal fields by seismic networks. Guidelines and chances; Monitoring geothermaler Felder durch seismische Netzwerke. Vorgaben und Chancen

Energy Technology Data Exchange (ETDEWEB)

Barth, Andreas [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Geophysikalisches Inst.; Gaucher, Emmanuel [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Abt. Geothermie

2012-07-01

The monitoring of geothermal power plants requires seismic networks in order to quantify ground motions at the earth's surface in the case of a possible micro seismicity or to describe spatio-temporal seismicity distribution in the reservoir. The first case requires official needs. The second case may help to develop the reservoirs. An optimal configuration of the seismic network may adequate for both tasks. It also can be a chance for a long-term investment for the overall benefit.

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

Science.gov (United States)

Prastowo, T.; Madlazim

2018-01-01

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

Analysis of the seismic catalogues for the Vrancea Region, Romania

International Nuclear Information System (INIS)

Romashkova, L.L.; Kossobokov, V.G.

2005-11-01

Vrancea (Romania) is a geographical region between Eastern and Southern Carpathian Mountains. The region is characterized by a rather high level of seismic activity mainly at intermediate (up to 200 km) depths. These intermediate-depth earthquakes occur between 45 deg-46 deg N and 26 deg-27 deg E. The shallow earthquakes are dispersed over a much broader territory. We performed the comparative analysis of earthquake catalogues available for Vrancea region aiming at the compilation of a data set, to be as complete and homogeneous as possible, which, hopefully, will be used for the prediction of strong and possibly moderate earthquakes in the region by means of M8 algorithm. The two catalogues under study are: 1) Global Hypocenter Data Base catalogue, NEIC (GHDB, 1989) and 2) local Vrancea seismic catalogue (Moldoveanu et al., 1995) and their updates. (author)

National Earthquake Information Center Seismic Event Detections on Multiple Scales

Science.gov (United States)

Patton, J.; Yeck, W. L.; Benz, H.; Earle, P. S.; Soto-Cordero, L.; Johnson, C. E.

2017-12-01

The U.S. Geological Survey National Earthquake Information Center (NEIC) monitors seismicity on local, regional, and global scales using automatic picks from more than 2,000 near-real time seismic stations. This presents unique challenges in automated event detection due to the high variability in data quality, network geometries and density, and distance-dependent variability in observed seismic signals. To lower the overall detection threshold while minimizing false detection rates, NEIC has begun to test the incorporation of new detection and picking algorithms, including multiband (Lomax et al., 2012) and kurtosis (Baillard et al., 2014) pickers, and a new bayesian associator (Glass 3.0). The Glass 3.0 associator allows for simultaneous processing of variably scaled detection grids, each with a unique set of nucleation criteria (e.g., nucleation threshold, minimum associated picks, nucleation phases) to meet specific monitoring goals. We test the efficacy of these new tools on event detection in networks of various scales and geometries, compare our results with previous catalogs, and discuss lessons learned. For example, we find that on local and regional scales, rapid nucleation of small events may require event nucleation with both P and higher-amplitude secondary phases (e.g., S or Lg). We provide examples of the implementation of a scale-independent associator for an induced seismicity sequence (local-scale), a large aftershock sequence (regional-scale), and for monitoring global seismicity. Baillard, C., Crawford, W. C., Ballu, V., Hibert, C., & Mangeney, A. (2014). An automatic kurtosis-based P-and S-phase picker designed for local seismic networks. Bulletin of the Seismological Society of America, 104(1), 394-409. Lomax, A., Satriano, C., & Vassallo, M. (2012). Automatic picker developments and optimization: FilterPicker - a robust, broadband picker for real-time seismic monitoring and earthquake early-warning, Seism. Res. Lett. , 83, 531-540, doi: 10

Post-seismic velocity changes following the 2010 Mw 7.1 Darfield earthquake, New Zealand, revealed by ambient seismic field analysis

Science.gov (United States)

Heckels, R. EG; Savage, M. K.; Townend, J.

2018-05-01

Quantifying seismic velocity changes following large earthquakes can provide insights into fault healing and reloading processes. This study presents temporal velocity changes detected following the 2010 September Mw 7.1 Darfield event in Canterbury, New Zealand. We use continuous waveform data from several temporary seismic networks lying on and surrounding the Greendale Fault, with a maximum interstation distance of 156 km. Nine-component, day-long Green's functions were computed for frequencies between 0.1 and 1.0 Hz for continuous seismic records from immediately after the 2010 September 04 earthquake until 2011 January 10. Using the moving-window cross-spectral method, seismic velocity changes were calculated. Over the study period, an increase in seismic velocity of 0.14 ± 0.04 per cent was determined near the Greendale Fault, providing a new constraint on post-seismic relaxation rates in the region. A depth analysis further showed that velocity changes were confined to the uppermost 5 km of the subsurface. We attribute the observed changes to post-seismic relaxation via crack healing of the Greendale Fault and throughout the surrounding region.

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

Science.gov (United States)

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

2017-12-01

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

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

Science.gov (United States)

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

2008-12-01

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

Seismic data restoration with a fast L1 norm trust region method

International Nuclear Information System (INIS)

Cao, Jingjie; Wang, Yanfei

2014-01-01

Seismic data restoration is a major strategy to provide reliable wavefield when field data dissatisfy the Shannon sampling theorem. Recovery by sparsity-promoting inversion often get sparse solutions of seismic data in a transformed domains, however, most methods for sparsity-promoting inversion are line-searching methods which are efficient but are inclined to obtain local solutions. Using trust region method which can provide globally convergent solutions is a good choice to overcome this shortcoming. A trust region method for sparse inversion has been proposed, however, the efficiency should be improved to suitable for large-scale computation. In this paper, a new L 1 norm trust region model is proposed for seismic data restoration and a robust gradient projection method for solving the sub-problem is utilized. Numerical results of synthetic and field data demonstrate that the proposed trust region method can get excellent computation speed and is a viable alternative for large-scale computation. (paper)

Location capability of a sparse regional network (RSTN) using a multi-phase earthquake location algorithm (REGLOC)

Energy Technology Data Exchange (ETDEWEB)

Hutchings, L.

1994-01-01

The Regional Seismic Test Network (RSTN) was deployed by the US Department of Energy (DOE) to determine whether data recorded by a regional network could be used to detect and accurately locate seismic events that might be clandestine nuclear tests. The purpose of this paper is to evaluate the location capability of the RSTN. A major part of this project was the development of the location algorithm REGLOC and application of Basian a prior statistics for determining the accuracy of the location estimates. REGLOC utilizes all identifiable phases, including backazimuth, in the location. Ninty-four events, distributed throughout the network area, detected by both the RSTN and located by local networks were used in the study. The location capability of the RSTN was evaluated by estimating the location accuracy, error ellipse accuracy, and the percentage of events that could be located, as a function of magnitude. The location accuracy was verified by comparing the RSTN results for the 94 events with published locations based on data from the local networks. The error ellipse accuracy was evaluated by determining whether the error ellipse includes the actual location. The percentage of events located was assessed by combining detection capability with location capability to determine the percentage of events that could be located within the study area. Events were located with both an average crustal model for the entire region, and with regional velocity models along with station corrections obtained from master events. Most events with a magnitude <3.0 can only be located with arrivals from one station. Their average location errors are 453 and 414 km for the average- and regional-velocity model locations, respectively. Single station locations are very unreliable because they depend on accurate backazimuth estimates, and backazimuth proved to be a very unreliable computation.

Seismicity Characterization and Velocity Structure of Northeast Russia

National Research Council Canada - National Science Library

Mackey, Kevin G; Fujita, Kazuya

2005-01-01

A seismicity catalog and associated list of phases for many events has been compiled for northeast Russia using published and unpublished data from the regional networks operating in eastern Russia...

First Quarter Hanford Seismic Report for Fiscal Year 2009

Energy Technology Data Exchange (ETDEWEB)

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

2009-03-15

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

Spots of Seismic Danger Extracted by Properties of Low-Frequency Seismic Noise

Science.gov (United States)

Lyubushin, Alexey

2013-04-01

A new method of seismic danger estimate is presented which is based on using properties of low-frequency seismic noise from broadband networks. Two statistics of noise waveforms are considered: multi-fractal singularity spectrum support width D and minimum normalized entropy En of squared orthogonal wavelet coefficients. The maps of D and En are plotted in the moving time window. Let us call the regions extracted by low values of D and high values of En as "spots of seismic danger" - SSD. Mean values of D and En are strongly anti-correlated - that is why statistics D and En extract the same SSD. Nevertheless their mutual considering is expedient because these parameters are based on different approaches. The physical mechanism which underlies the method is consolidation of small blocks of the Earth's crust into the large one before the strong earthquake. This effect has a consequence that seismic noise does not include spikes which are connected with mutual movements of small blocks. The absence of irregular spikes in the noise follows the decreasing of D and increasing of entropy En. The stability in space and size of the SSD provides estimates of the place and energy of the probable future earthquake. The increasing or decreasing of SSD size and minimum or maximum values of D and En within SSD allows estimate the trend of seismic danger. The method is illustrating by the analysis of seismic noise from broadband seismic network F-net in Japan [1-5]. Statistically significant decreasing of D allowed a hypothesis about approaching Japan to a future seismic catastrophe to be formulated at the middle of 2008. The peculiarities of correlation coefficient estimate within 1 year time window between median values of D and generalized Hurst exponent allowed to make a decision that starting from July of 2010 Japan come to the state of waiting strong earthquake [3]. The method extracted a huge SSD near Japan which includes the region of future Tohoku mega-earthquake and the

Remotely Triggered Earthquakes Recorded by EarthScope's Transportable Array and Regional Seismic Networks: A Case Study Of Four Large Earthquakes

Science.gov (United States)

Velasco, A. A.; Cerda, I.; Linville, L.; Kilb, D. L.; Pankow, K. L.

2013-05-01

Changes in field stress required to trigger earthquakes have been classified in two basic ways: static and dynamic triggering. Static triggering occurs when an earthquake that releases accumulated strain along a fault stress loads a nearby fault. Dynamic triggering occurs when an earthquake is induced by the passing of seismic waves from a large mainshock located at least two or more fault lengths from the epicenter of the main shock. We investigate details of dynamic triggering using data collected from EarthScope's USArray and regional seismic networks located in the United States. Triggered events are identified using an optimized automated detector based on the ratio of short term to long term average (Antelope software). Following the automated processing, the flagged waveforms are individually analyzed, in both the time and frequency domains, to determine if the increased detection rates correspond to local earthquakes (i.e., potentially remotely triggered aftershocks). Here, we show results using this automated schema applied to data from four large, but characteristically different, earthquakes -- Chile (Mw 8.8 2010), Tokoku-Oki (Mw 9.0 2011), Baja California (Mw 7.2 2010) and Wells Nevada (Mw 6.0 2008). For each of our four mainshocks, the number of detections within the 10 hour time windows span a large range (1 to over 200) and statistically >20% of the waveforms show evidence of anomalous signals following the mainshock. The results will help provide for a better understanding of the physical mechanisms involved in dynamic earthquake triggering and will help identify zones in the continental U.S. that may be more susceptible to dynamic earthquake triggering.

Seismic cycle and seismic risk of an active faults network: the Corinth rift case (Greece)

International Nuclear Information System (INIS)

Boiselet, Aurelien

2014-01-01

The Corinth rift (Greece) is one of the regions with the highest strain rates (16 mm/y extension rate) in the Euro-Mediterranean area and as such it has long been identified as a site of major importance for earthquake studies in Europe (20 years of research by the Corinth Rift Laboratory and 4 years of in-depth studies by the ANR-SISCOR project). This enhanced knowledge, acquired in particular, in the western part of the Gulf of Corinth (CRL region), an area about 50 by 40 km 2 , between the city of Patras to the west and the city of Aigion to the east, provides an excellent opportunity to compare fault-based (FB) and classical seismo-tectonic (ST) approaches currently used in seismic hazard assessment studies. An homogeneous earthquake catalogue was thus constructed for the purpose of this study along with a comprehensive database of all relevant geological, geodetic and geophysical information available in the literature and recently collected within the ANR-SISCOR project. The homogenized Mw earthquake catalogue is composed of data from the National Observatory of Athens and from the university of Thessaloniki as well as data acquired through historical and instrumental work performed within the ANR-SISCOR group for the CRL region. A frequency magnitude analysis confirms that seismicity rates are governed by Gutenberg-Richter (GR) statistic for 1.2 =6 earthquakes were computed for the region of study. Time dependent models (Brownian Passage time and Weibull probability distributions) were also explored. The probability (normalized by area) of a M≥6.0 earthquake is found to be greater in the CRL region compared to the eastern part of the Corinth rift. Probability estimates corresponding to the 16. and 84. percentile are also provided, as a means of representing the range of uncertainties in the results. Probability estimates based on the ST-approach are then compared to those based on the FB approach approach. In general ST tends to overestimate probabilities

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

The contribution of the Global Change Observatory Central Asia to seismic hazard and risk assessment in the Central Asian region

Science.gov (United States)

Parolai, S.; Bindi, D.; Haberland, C. A.; Pittore, M.; Pilz, M.; Rosenau, M.; Schurr, B.; Wieland, M.; Yuan, X.

2012-12-01

Central Asia has one of the world's highest levels of earthquake hazard, owing to its exceptionally high deformation rates. Moreover, vulnerability to natural disasters in general is increasing, due to rising populations and a growing dependence on complex lifelines and technology. Therefore, there is an urgent need to undertake seismic hazard and risk assessment in this region, while at the same time improving upon existing methodologies, including the consideration of temporal variability in the seismic hazard, and in structural and social vulnerability. Over the last few years, the German Research Center for Geosciences (GFZ), in collaboration with local partners, has initiated a number of scientific activities within the framework of the Global Change Observatory Central Asia (GCO-CA). The work is divided into projects with specific concerns: - The installation and maintenance of the Central-Asian Real-time Earthquake MOnitoring Network (CAREMON) and the setup of a permanent wireless mesh network for structural health monitoring in Bishkek. - The TIPAGE and TIPTIMON projects focus on the geodynamics of the Tien-Shan, Pamir and Hindu Kush region, the deepest and most active intra-continental subduction zone in the world. The work covers time scales from millions of years to short-term snapshots based on geophysical measurements of seismotectonic activity and of the physical properties of the crust and upper mantle, as well as their coupling with other surface processes (e.g., landslides). - Existing risk analysis methods assume time-independent earthquake hazard and risk, although temporal changes are likely to occur due to, for example, co- and post-seismic changes in the regional stress field. We therefore aim to develop systematic time-dependent hazard and risk analysis methods in order to undertake the temporal quantification of earthquake activity (PROGRESS). - To improve seismic hazard assessment for better loss estimation, detailed site effects studies

Automatic reconstruction of fault networks from seismicity catalogs including location uncertainty

International Nuclear Information System (INIS)

Wang, Y.

2013-01-01

provide the best agreement with independently observed focal mechanisms. Tests on synthetic catalogues allow qualification of the performance of the fitting method and of the various validation procedures. The ACLUD method is able to provide solutions that are close to the expected ones, especially for the BIC and focal mechanism-based techniques. The clustering method complemented by the validation step based on focal mechanisms provides good solutions even in the presence of a significant spatial background seismicity rate. As the new clustering method is able to deal with most of the information contained in modern earthquake catalogues, the geometry of the local station network may improve or alter the reconstruction of the underlying fault system. This is illustrated by using the highest-quality data selected using station network criteria which results in reconstructed fault planes of higher quality and accuracy. Using lower-quality data can lead to unstable and unreliable fault networks and may introduce artefacts, in particular in regions of a complex fault structure. The results highlight the need to carefully assess the quality and reliability of reconstructed fault networks from real data that unavoidably involve the clustering of data of heterogeneous quality. Based on realistic tests with synthetic fault network structures, the results also stress the importance of accounting for under-sampled sub-fault structures as well as for spatially-inhomogeneous location uncertainties. The fault reconstruction method is applied to two real datasets at two very different spatial scales, i.e. the 1992 Landers M7 earthquake sequence in Southern California, and the Basel (Switzerland) induced seismicity sequence. In both case studies, fault network results reasonably compare with independent structural analysis data, suggesting highly complex fault structures for both, at the scale of the Landers earthquake covering a volume of about 70,000 km 3 and in the volume of the

Automatic reconstruction of fault networks from seismicity catalogs including location uncertainty

Energy Technology Data Exchange (ETDEWEB)

Wang, Y.

2013-07-01

provide the best agreement with independently observed focal mechanisms. Tests on synthetic catalogues allow qualification of the performance of the fitting method and of the various validation procedures. The ACLUD method is able to provide solutions that are close to the expected ones, especially for the BIC and focal mechanism-based techniques. The clustering method complemented by the validation step based on focal mechanisms provides good solutions even in the presence of a significant spatial background seismicity rate. As the new clustering method is able to deal with most of the information contained in modern earthquake catalogues, the geometry of the local station network may improve or alter the reconstruction of the underlying fault system. This is illustrated by using the highest-quality data selected using station network criteria which results in reconstructed fault planes of higher quality and accuracy. Using lower-quality data can lead to unstable and unreliable fault networks and may introduce artefacts, in particular in regions of a complex fault structure. The results highlight the need to carefully assess the quality and reliability of reconstructed fault networks from real data that unavoidably involve the clustering of data of heterogeneous quality. Based on realistic tests with synthetic fault network structures, the results also stress the importance of accounting for under-sampled sub-fault structures as well as for spatially-inhomogeneous location uncertainties. The fault reconstruction method is applied to two real datasets at two very different spatial scales, i.e. the 1992 Landers M7 earthquake sequence in Southern California, and the Basel (Switzerland) induced seismicity sequence. In both case studies, fault network results reasonably compare with independent structural analysis data, suggesting highly complex fault structures for both, at the scale of the Landers earthquake covering a volume of about 70,000 km{sup 3} and in the volume of

Building Capacity for Earthquake Monitoring: Linking Regional Networks with the Global Community

Science.gov (United States)

Willemann, R. J.; Lerner-Lam, A.

2006-12-01

Installing or upgrading a seismic monitoring network is often among the mitigation efforts after earthquake disasters, and this is happening in response to the events both in Sumatra during December 2004 and in Pakistan during October 2005. These networks can yield improved hazard assessment, more resilient buildings where they are most needed, and emergency relief directed more quickly to the worst hit areas after the next large earthquake. Several commercial organizations are well prepared for the fleeting opportunity to provide the instruments that comprise a seismic network, including sensors, data loggers, telemetry stations, and the computers and software required for the network center. But seismic monitoring requires more than hardware and software, no matter how advanced. A well-trained staff is required to select appropriate and mutually compatible components, install and maintain telemetered stations, manage and archive data, and perform the analyses that actually yield the intended benefits. Monitoring is more effective when network operators cooperate with a larger community through free and open exchange of data, sharing information about working practices, and international collaboration in research. As an academic consortium, a facility operator and a founding member of the International Federation of Digital Seismographic Networks, IRIS has access to a broad range of expertise with the skills that are required to help design, install, and operate a seismic network and earthquake analysis center, and stimulate the core training for the professional teams required to establish and maintain these facilities. But delivering expertise quickly when and where it is unexpectedly in demand requires advance planning and coordination in order to respond to the needs of organizations that are building a seismic network, either with tight time constraints imposed by the budget cycles of aid agencies following a disastrous earthquake, or as part of more informed

Seismic activity prediction using computational intelligence techniques in northern Pakistan

Science.gov (United States)

Asim, Khawaja M.; Awais, Muhammad; Martínez-Álvarez, F.; Iqbal, Talat

2017-10-01

Earthquake prediction study is carried out for the region of northern Pakistan. The prediction methodology includes interdisciplinary interaction of seismology and computational intelligence. Eight seismic parameters are computed based upon the past earthquakes. Predictive ability of these eight seismic parameters is evaluated in terms of information gain, which leads to the selection of six parameters to be used in prediction. Multiple computationally intelligent models have been developed for earthquake prediction using selected seismic parameters. These models include feed-forward neural network, recurrent neural network, random forest, multi layer perceptron, radial basis neural network, and support vector machine. The performance of every prediction model is evaluated and McNemar's statistical test is applied to observe the statistical significance of computational methodologies. Feed-forward neural network shows statistically significant predictions along with accuracy of 75% and positive predictive value of 78% in context of northern Pakistan.

Erosion Associated with Seismically-Induced Landslides in the Middle Longmen Shan Region, Eastern Tibetan Plateau, China

Directory of Open Access Journals (Sweden)

Zhikun Ren

2017-08-01

Full Text Available The 2008 Wenchuan earthquake and associated co-seismic landslide was the most recent expression of the rapid deformation and erosion occurring in the eastern Tibetan Plateau. The erosion associated with co-seismic landslides balances the long-term tectonic uplift in the topographic evolution of the region; however, the quantitative relationship between earthquakes, uplift, and erosion is still unknown. In order to quantitatively distinguish the seismically-induced erosion in the total erosion, here, we quantify the Wenchuan earthquake-induced erosion using the digital elevation model (DEM differential method and previously-reported landslide volumes. Our results show that the seismically-induced erosion is comparable with the pre-earthquake short-term erosion. The seismically-induced erosion rate contributes ~50% of the total erosion rate, which suggests that the local topographic evolution of the middle Longmen Shan region may be closely related to tectonic events, such as the 2008 Wenchuan earthquake. We propose that seismically-induced erosion is a very important component of the total erosion, particularly in active orogenic regions. Our results demonstrate that the remote sensing technique of differential DEM provides a powerful tool for evaluating the volume of co-seismic landslides produced in intermountain regions by strong earthquakes.

Seismic sequences in the Sombrero Seismic Zone

Science.gov (United States)

Pulliam, J.; Huerfano, V. A.; ten Brink, U.; von Hillebrandt, C.

2007-05-01

The northeastern Caribbean, in the vicinity of Puerto Rico and the Virgin Islands, has a long and well-documented history of devastating earthquakes and tsunamis, including major events in 1670, 1787, 1867, 1916, 1918, and 1943. Recently, seismicity has been concentrated to the north and west of the British Virgin Islands, in the region referred to as the Sombrero Seismic Zone by the Puerto Rico Seismic Network (PRSN). In the combined seismicity catalog maintained by the PRSN, several hundred small to moderate magnitude events can be found in this region prior to 2006. However, beginning in 2006 and continuing to the present, the rate of seismicity in the Sombrero suddenly increased, and a new locus of activity developed to the east of the previous location. Accurate estimates of seismic hazard, and the tsunamigenic potential of seismic events, depend on an accurate and comprehensive understanding of how strain is being accommodated in this corner region. Are faults locked and accumulating strain for release in a major event? Or is strain being released via slip over a diffuse system of faults? A careful analysis of seismicity patterns in the Sombrero region has the potential to both identify faults and modes of failure, provided the aggregation scheme is tuned to properly identify related events. To this end, we experimented with a scheme to identify seismic sequences based on physical and temporal proximity, under the assumptions that (a) events occur on related fault systems as stress is refocused by immediately previous events and (b) such 'stress waves' die out with time, so that two events that occur on the same system within a relatively short time window can be said to have a similar 'trigger' in ways that two nearby events that occurred years apart cannot. Patterns that emerge from the identification, temporal sequence, and refined locations of such sequences of events carry information about stress accommodation that is obscured by large clouds of

Evaluation and optimization of seismic networks and algorithms for earthquake early warning – the case of Istanbul (Turkey)

OpenAIRE

Oth, Adrien; Böse, Maren; Wenzel, Friedemann; Köhler, Nina; Erdik, Mustafa

2010-01-01

Earthquake early warning (EEW) systems should provide reliable warnings as quickly as possible with a minimum number of false and missed alarms. Using the example of the megacity Istanbul and based on a set of simulated scenario earthquakes, we present a novel approach for evaluating and optimizing seismic networks for EEW, in particular in regions with a scarce number of instrumentally recorded earthquakes. We show that, while the current station locations of the existing Istanbul EEW system...

Seismic network based detection, classification and location of volcanic tremors

Science.gov (United States)

Nikolai, S.; Soubestre, J.; Seydoux, L.; de Rosny, J.; Droznin, D.; Droznina, S.; Senyukov, S.; Gordeev, E.

2017-12-01

Volcanic tremors constitute an important attribute of volcanic unrest in many volcanoes, and their detection and characterization is a challenging issue of volcano monitoring. The main goal of the present work is to develop a network-based method to automatically classify volcanic tremors, to locate their sources and to estimate the associated wave speed. The method is applied to four and a half years of seismic data continuously recorded by 19 permanent seismic stations in the vicinity of the Klyuchevskoy volcanic group (KVG) in Kamchatka (Russia), where five volcanoes were erupting during the considered time period. The method is based on the analysis of eigenvalues and eigenvectors of the daily array covariance matrix. As a first step, following Seydoux et al. (2016), most coherent signals corresponding to dominating tremor sources are detected based on the width of the covariance matrix eigenvalues distribution. With this approach, the volcanic tremors of the two volcanoes known as most active during the considered period, Klyuchevskoy and Tolbachik, are efficiently detected. As a next step, we consider the array covariance matrix's first eigenvectors computed every day. The main hypothesis of our analysis is that these eigenvectors represent the principal component of the daily seismic wavefield and, for days with tremor activity, characterize the dominant tremor sources. Those first eigenvectors can therefore be used as network-based fingerprints of tremor sources. A clustering process is developed to analyze this collection of first eigenvectors, using correlation coefficient as a measure of their similarity. Then, we locate tremor sources based on cross-correlations amplitudes. We characterize seven tremor sources associated with different periods of activity of four volcanoes: Tolbachik, Klyuchevskoy, Shiveluch, and Kizimen. The developed method does not require a priori knowledge, is fully automatic and the database of network-based tremor fingerprints

Focal mechanisms in the southern Aegean from temporary seismic networks – implications for the regional stress field and ongoing deformation processes

OpenAIRE

Friederich, W.; Brüstle, A.; Küperkoch, L.; Meier, T.; Lamara, S.; Working Group, Egelados

2014-01-01

The lateral variation of the stress field in the southern Aegean plate and the subducting Hellenic slab is determined from recordings of seismicity obtained with the CYCNET and EGELADOS networks in the years from 2002 to 2007. First motions from 7000 well-located microearthquakes were analysed to produce 540 well-constrained focal mechanisms. They were complemented by another 140 derived by waveform matching of records from larger events. Most of these earth...

Detailed seismicity analysis in the SE of Romania (Dobrogea region)

Science.gov (United States)

Rogozea, Maria; Radulian, Mircea; Ghica, Daniela; Popa, Mihaela

2014-05-01

The purpose of this paper is to analyze the seismicity in the south-eastern part of Romania, in the Dobrogea region (namely the Predobrogean Depression and Black Sea area). Predobrogean Depression is the name attributed to the structures belonging to the Scythian Platform. The seismic activity is moderate with most significant earthquakes at the boundary between the North Dobrogea Orogen and Scythian Platform (Sf. Gheorghe fault). The largest magnitude event was recorded in 02.11.1871 (Mw = 5.3). Other events with magnitude above 4 were observed close to Tulcea city (13.11.1981, Mw = 5.1, 03.09.204, Mw =5.1) and Galati city (11.09.1980, Mw = 4.2). Recently, an earthquake swarm of 406 events extended over two months and a half (23 September - 5 December 2013) was produced in the Galati area (maximum magnitude 3.9). The deformation field has an extensional regime, as resulted from fault plane solutions and geotectonic investigations. The maximum expected magnitude in this area is estimated at Mw = 5.5. The seismic activity in the Black Sea area, close to Romania seashore and north-east Bulgarian seashore, concentrates along Shabla fault system. Large shocks (magnitude above 7) are reported here at intervals of a few centuries. The most recent major shock was recorded on 31 January 1901 (Mw = 7.2) in Shabla region, Bulgaria. To characterize seismicity parameters, the Romanian catalogue of the National Institute of Earth Physics was used as a basic input. The catalogue was revised as concerns historical information by reanalyzing macroseismic data and for the recent events, by applying up-to-date tools to relocate and re-parametrize the seismic sources.

Extending Resolution of Fault Slip With Geodetic Networks Through Optimal Network Design

Science.gov (United States)

Sathiakumar, Sharadha; Barbot, Sylvain Denis; Agram, Piyush

2017-12-01

Geodetic networks consisting of high precision and high rate Global Navigation Satellite Systems (GNSS) stations continuously monitor seismically active regions of the world. These networks measure surface displacements and the amount of geodetic strain accumulated in the region and give insight into the seismic potential. SuGar (Sumatra GPS Array) in Sumatra, GEONET (GNSS Earth Observation Network System) in Japan, and PBO (Plate Boundary Observatory) in California are some examples of established networks around the world that are constantly expanding with the addition of new stations to improve the quality of measurements. However, installing new stations to existing networks is tedious and expensive. Therefore, it is important to choose suitable locations for new stations to increase the precision obtained in measuring the geophysical parameters of interest. Here we describe a methodology to design optimal geodetic networks that augment the existing system and use it to investigate seismo-tectonics at convergent and transform boundaries considering land-based and seafloor geodesy. The proposed network design optimization would be pivotal to better understand seismic and tsunami hazards around the world. Land-based and seafloor networks can monitor fault slip around subduction zones with significant resolution, but transform faults are more challenging to monitor due to their near-vertical geometry.

Teaching hands-on geophysics: examples from the Rū seismic network in New Zealand

International Nuclear Information System (INIS)

Van Wijk, Kasper; Simpson, Jonathan; Adam, Ludmila

2017-01-01

Education in physics and geosciences can be effectively illustrated by the analysis of earthquakes and the subsequent propagation of seismic waves in the Earth. Educational seismology has matured to a level where both the hard- and software are robust and user friendly. This has resulted in successful implementation of educational networks around the world. Seismic data recorded by students are of such quality that these can be used in classic earthquake location exercises, for example. But even ocean waves weakly coupled into the Earth’s crust can now be recorded on educational seismometers. These signals are not just noise, but form the basis of more recent developments in seismology, such as seismic interferometry, where seismic waves generated by ocean waves—instead of earthquakes—can be used to infer information about the Earth’s interior. Here, we introduce an earthquake location exercise and an analysis of ambient seismic noise, and present examples. Data are provided, and all needed software is freely available. (review)

An automated multi-scale network-based scheme for detection and location of seismic sources

Science.gov (United States)

Poiata, N.; Aden-Antoniow, F.; Satriano, C.; Bernard, P.; Vilotte, J. P.; Obara, K.

2017-12-01

We present a recently developed method - BackTrackBB (Poiata et al. 2016) - allowing to image energy radiation from different seismic sources (e.g., earthquakes, LFEs, tremors) in different tectonic environments using continuous seismic records. The method exploits multi-scale frequency-selective coherence in the wave field, recorded by regional seismic networks or local arrays. The detection and location scheme is based on space-time reconstruction of the seismic sources through an imaging function built from the sum of station-pair time-delay likelihood functions, projected onto theoretical 3D time-delay grids. This imaging function is interpreted as the location likelihood of the seismic source. A signal pre-processing step constructs a multi-band statistical representation of the non stationary signal, i.e. time series, by means of higher-order statistics or energy envelope characteristic functions. Such signal-processing is designed to detect in time signal transients - of different scales and a priori unknown predominant frequency - potentially associated with a variety of sources (e.g., earthquakes, LFE, tremors), and to improve the performance and the robustness of the detection-and-location location step. The initial detection-location, based on a single phase analysis with the P- or S-phase only, can then be improved recursively in a station selection scheme. This scheme - exploiting the 3-component records - makes use of P- and S-phase characteristic functions, extracted after a polarization analysis of the event waveforms, and combines the single phase imaging functions with the S-P differential imaging functions. The performance of the method is demonstrated here in different tectonic environments: (1) analysis of the one year long precursory phase of 2014 Iquique earthquake in Chile; (2) detection and location of tectonic tremor sources and low-frequency earthquakes during the multiple episodes of tectonic tremor activity in southwestern Japan.

Annual Hanford Seismic Report for Fiscal Year 2008

Energy Technology Data Exchange (ETDEWEB)

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

2008-12-29

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 fiscal year 2008, the Hanford Seismic Network recorded 1431 triggers on the seismometer system, which included 112 seismic events in the southeast Washington area and an additional 422 regional and teleseismic events. There were 74 events determined to be local earthquakes relevant to the Hanford Site. The highest-magnitude event (3.7 Mc) occurred on May 18, 2008, and was located approximately 17 km east of Prosser at a depth of 20.5 km. With regard to the depth distribution, 13 earthquakes were located at shallow depths (less than 4 km, most likely in the Columbia River basalts), 45 earthquakes were located at intermediate depths (between 4 and 9 km, most likely in the pre-basalt sediments), and 16 earthquakes were located at depths greater than 9 km, within the crystalline basement. Geographically, 54 earthquakes were located in swarm areas and 20 earthquakes were classified as random events. The May 18 earthquake was the highest magnitude event recorded since 1975 in the vicinity of the Hanford Site (between 46 degrees and 47 degrees north latitude and

Proterozoic structure, cambrian rifting, and younger faulting as revealed by a regional seismic reflection network in the Southern Illinois Basin

Science.gov (United States)

Potter, C.J.; Drahovzal, James A.; Sargent, M.L.; McBride, J.H.

1997-01-01

Four high-quality seismic reflection profiles through the southern Illinois Basin, totaling 245 km in length, provide an excellent regional subsurface stratigraphic and structural framework for evaluation of seismic risk, hydrocarbon occurrence, and other regional geologic studies. These data provide extensive subsurface information on the geometry of the intersection of the Cambrian Reelfoot and Rough Creek rifts, on extensive Proterozoic reflection sequences, and on structures (including the Fluorspar Area Fault Complex and Hicks Dome) that underlie a transitional area between the well-defined New Madrid seismic zone (to the southwest) and a more diffuse area of seismicity in the southern Illinois Basin. Our principal interpretations from these data are listed here in order of geologic age, from oldest to youngest: 1. Prominent Proterozoic layering, possibly equivalent to Proterozoic (???1 Ga) Middle Run Formation clastic strata and underlying (1.3-1.5 Ga) volcanic rocks of the East Continent rift basin, has been strongly deformed, probably as part of the Grenville foreland fold and thrust belt. 2. A well-defined angular unconformity is seen in many places between Proterozoic and Cambrian strata; a post-Grenville Proterozoic sequence is also apparent locally, directly beneath the base of the Cambrian. 3. We infer a major reversal in Cambrian rift polarity (accommodation zone) in the Rough Creek Graben in western Kentucky. 4. Seismic facies analysis suggests the presence of basin-floor fan complexes at and near the base of the Cambrian interval and within parts of a Proterozoic post-Grenville sequence in several parts of the Rough Creek Graben. 5. There is an abrupt pinchout of the Mount Simon Sandstone against crystalline basement beneath the Dale Dome (near the Texaco no. 1 Cuppy well, Hamilton County) in southeastern Illinois, and a more gradual Mount Simon pinchout to the southeast. 6. Where crossed by the seismic reflection line in southeast Illinois, some

Knowledge discovery from seismic data using neural networks; Descoberta de conhecimento a partir de dados sismicos utilizando redes neurais

Energy Technology Data Exchange (ETDEWEB)

Paula, Wesley R. de; Costa, Bruno A.D.; Gomes, Herman M. [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

2004-07-01

The analysis and interpretation of seismic data is of fundamental importance to the Oil Industry, since it helps discover geologic formations that are conducive to hydrocarbon accumulation. The use of seismic data in reservoir characterization may be performed through localized data inspections and clustering based on features of common seismic responses. This clustering or classification can be performed in two basic ways: visually, with the help of graphical tools; or using automatic classification techniques, such as statistical models and artificial neural networks. Neural network based methods are generally superior to rule- or knowledge-based systems, since they have a better generalization capability and are fault tolerant. Within this context, the main objective of this work is to describe methods that employ the two main neural network based approaches (supervised and unsupervised) in knowledge discovery from seismic data. Initially, the implementation and experiments were focused on the problem of seismic facies recognition using the unsupervised approach, but in future works, the implementation of the supervised approach, an application to fault detection and a parallel implementation of the proposed methods are planned. (author)

REGIONAL SEISMIC AMPLITUDE MODELING AND TOMOGRAPHY FOR EARTHQUAKE-EXPLOSION DISCRIMINATION

Energy Technology Data Exchange (ETDEWEB)

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

2008-07-08

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

Reassessment of probabilistic seismic hazard in the Marmara region

Science.gov (United States)

Kalkan, Erol; Gulkan, Polat; Yilmaz, Nazan; Çelebi, Mehmet

2009-01-01

In 1999, the eastern coastline of the Marmara region (Turkey) witnessed increased seismic activity on the North Anatolian fault (NAF) system with two damaging earthquakes (M 7.4 Kocaeli and M 7.2 D??zce) that occurred almost three months apart. These events have reduced stress on the western segment of the NAF where it continues under the Marmara Sea. The undersea fault segments have been recently explored using bathymetric and reflection surveys. These recent findings helped scientists to understand the seismotectonic environment of the Marmara basin, which has remained a perplexing tectonic domain. On the basis of collected new data, seismic hazard of the Marmara region is reassessed using a probabilistic approach. Two different earthquake source models: (1) the smoothed-gridded seismicity model and (2) fault model and alternate magnitude-frequency relations, Gutenberg-Richter and characteristic, were used with local and imported ground-motion-prediction equations. Regional exposure is computed and quantified on a set of hazard maps that provide peak horizontal ground acceleration (PGA) and spectral acceleration at 0.2 and 1.0 sec on uniform firm-rock site condition (760 m=sec average shear wave velocity in the upper 30 m). These acceleration levels were computed for ground motions having 2% and 10% probabilities of exceedance in 50 yr, corresponding to return periods of about 2475 and 475 yr, respectively. The maximum PGA computed (at rock site) is 1.5g along the fault segments of the NAF zone extending into the Marmara Sea. The new maps generally show 10% to 15% increase for PGA, 0.2 and 1.0 sec spectral acceleration values across much of Marmara compared to previous regional hazard maps. Hazard curves and smooth design spectra for three site conditions: rock, soil, and soft-soil are provided for the Istanbul metropolitan area as possible tools in future risk estimates.

Evaluation of geological conditions for coalbed methane occurrence based on 3D seismic information: a case study in Fowa region, Xinjing coal mine, China

Science.gov (United States)

Li, Juanjuan; Li, Fanjia; Hu, Mingshun; Zhang, Wei; Pan, Dongming

2017-04-01

The research on geological conditions of coalbed methane (CBM) occurrence is of great significance for predicting the high abundance CBM rich region and gas outburst risk area pre-warning. The No. 3 coal seam, in Yangquan coalfield of Qinshui basin, is the research target studied by 3D seismic exploration technique. The geological factors which affect CBM occurrence are interpreted based on the 3D seismic information. First, the geological structure (faults, folds, and collapse columns) is found out by the 3D seismic structural interpretation and the information of buried depth and thickness of the coal seam is calculated by the seismic horizons. Second, 3D elastic impedance (EI) and natural gamma attribute volumes are generated by prestack EI inversion and multi-attribute probabilistic neural network (PNN) inversion techniques which reflect the information of coal structure types and lithology of the roof and floor. Then, the information of metamorphic degree of seam and hydrogeology conditions can be obtained by the geological data. Consequently, geological conditions of CBM occurrence in No. 3 coal seam are evaluated which will provide scientific reference for high abundance CBM rich region prediction and gas outburst risk area pre-warning.

Seismic Tomography and the Development of a State Velocity Profile

Science.gov (United States)

Marsh, S. J.; Nakata, N.

2017-12-01

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

Some characteristics of the seismicity of the Tyrrhenian Sea Region

Directory of Open Access Journals (Sweden)

P. HEDERVARI

1974-06-01

Full Text Available In the first p a r t of the paper the seismic strain release of the T y r r h e n i a n Sea Region (including Italy, as the function of time, is examined on the basis of t h e d a t a of the e a r t h q u a k e s t h a t took place f r om 1901.01.01 to 1970.12.31, between the northern l a t i t u d e s of 34° and 44° and between the eastern longitudes of 8° and 18.5°, respectively. All registered shocks with a R i c h t e r - m a g n i t u d e of 5.5 or over it were considered, i n d e p e n d e n t l y f r om t h e focal d e p t h . Three periods were recognized in the a c t i v i t y ; t h e lengths of which are not t h e same, however. I n the second p a r t the elastic strain release in accordance with the focal d e p t h of t h e same e a r t h q u a k e s is t r e a t e d briefly. It was found t h at t h e t o t a l strain-release had a maximum value in t h e depth between 0 and 74 kms and there was a minimum between the depth of 300 and 524 kins with an interval between 375 and 449 kms within which no earthquakes occurred at all. The general p a t t e r n of the d i s t r i b u t i o n of seismicity as t h e f u n c t i o n of hypocentral d e p t h reminds to the well-known picture, one can experience in other regions where i n t e r m e d i a t e and deep shocks occur. This s t a t e m e n t is consistent w i t h t h e idea, according to which t h e seismicity of t h e Tyrrhenian Sea Region can be discussed and explained in t h e light of t h e theory of new global tectonics. F i n a l l y , in the t h i r d p a r t of the study, the authors have s t a t e d t h at in some cases multiple events occurred b e n e a t h t h e Tyrrhenian Sea Region. Such multiple seismic events were detected in the case of other areas, such as the Fiji-Tonga-Kermadec Region, the seismic belt of South America etc., — but, according to the knowledge of t h e authors, this is t h e first occasion when multiple seismic events are

Seismic security assessment of earth and rockfill dams located in epicentral regions

Energy Technology Data Exchange (ETDEWEB)

Oldecop, L.; Zabala, F.; Rodari, R. [San Juan National Univ., San Juan (Argentina). Instituto de Invest. Antisismicas

2004-07-01

The seismic safety of dams is of great interest to the midwest region of Argentina, the most seismically active area in the country. This paper examines factors controlling the design of dams subjected to earthquake action, criteria for safety verification and the analysis tools currently available. Data of dams, active faults and epicenters of historic earthquakes in the region were provided. Paleoseismicity research was suggested as an important area of research, potentially enhancing an understanding of a region's seismic activity. It was concluded that analysis tools currently used in engineering include simple models offering advantages in reliability and ease of result interpretation, but have shortcomings in their applicability. Care must be taken in the validation and interpretation of these models, particularly when the behaviour of a dam includes complex phenomena. More sophisticated analysis tools currently available are difficult to apply, largely due to the complexity of algorithms in the models. It was also concluded that in order to overcome difficulties in both simple and complex models, predictions should be contrasted with real behaviour data. Data from measurement of seismic behaviour is still relatively scarce, presenting an obstacle towards the further use of more sophisticated analysis tools, as they are not as yet tested against measurements and observations of real cases. 15 refs., 2 tabs., 11 figs.

Earthquake hazard in Northeast India – A seismic microzonation ...

Indian Academy of Sciences (India)

microzonation approach with typical case studies from .... the other hand, Guwahati city represents a case of well-formed basin with ... earthquake prone regions towards developing its ... tonic network and the observed seismicity has been.

Crowd-Sourcing Seismic Data for Education and Research Opportunities with the Quake-Catcher Network

Science.gov (United States)

Sumy, D. F.; DeGroot, R. M.; Benthien, M. L.; Cochran, E. S.; Taber, J. J.

2016-12-01

The Quake Catcher Network (QCN; quakecatcher.net) uses low cost micro-electro-mechanical system (MEMS) sensors hosted by volunteers to collect seismic data. Volunteers use accelerometers internal to laptop computers, phones, tablets or small (the size of a matchbox) MEMS sensors plugged into desktop computers using a USB connector to collect scientifically useful data. Data are collected and sent to a central server using the Berkeley Open Infrastructure for Network Computing (BOINC) distributed computing software. Since 2008, sensors installed in museums, schools, offices, and residences have collected thousands of earthquake records, including the 2010 M8.8 Maule, Chile, the 2010 M7.1 Darfield, New Zealand, and 2015 M7.8 Gorkha, Nepal earthquakes. In 2016, the QCN in the United States transitioned to the Incorporated Research Institutions for Seismology (IRIS) Consortium and the Southern California Earthquake Center (SCEC), which are facilities funded through the National Science Foundation and the United States Geological Survey, respectively. The transition has allowed for an influx of new ideas and new education related efforts, which include focused installations in several school districts in southern California, on Native American reservations in North Dakota, and in the most seismically active state in the contiguous U.S. - Oklahoma. We present and describe these recent educational opportunities, and highlight how QCN has engaged a wide sector of the public in scientific data collection, particularly through the QCN-EPIcenter Network and NASA Mars InSight teacher programs. QCN provides the public with information and insight into how seismic data are collected, and how researchers use these data to better understand and characterize seismic activity. Lastly, we describe how students use data recorded by QCN sensors installed in their classrooms to explore and investigate felt earthquakes, and look towards the bright future of the network.

Improvement of IDC/CTBTO Event Locations in Latin America and the Caribbean Using a Regional Seismic Travel Time Model

Science.gov (United States)

Given, J. W.; Guendel, F.

2013-05-01

The International Data Centre is a vital element of the Comprehensive Test Ban Treaty (CTBT) verification mechanism. The fundamental mission of the International Data Centre (IDC) is to collect, process, and analyze monitoring data and to present results as event bulletins to Member States. For the IDC and in particular for waveform technologies, a key measure of the quality of its products is the accuracy by which every detected event is located. Accurate event location is crucial for purposes of an On Site Inspection (OSI), which would confirm the conduct of a nuclear test. Thus it is important for the IDC monitoring and data analysis to adopt new processing algorithms that improve the accuracy of event location. Among them the development of new algorithms to compute regional seismic travel times through 3-dimensional models have greatly increased IDC's location precision, the reduction of computational time, allowing forward and inverse modeling of large data sets. One of these algorithms has been the Regional Seismic Travel Time model (RSTT) of Myers et al., (2011). The RSTT model is nominally a global model; however, it currently covers only North America and Eurasia in sufficient detail. It is the intention CTBTO's Provisional Technical Secretariat and the IDC to extend the RSTT model to other regions of the earth, e.g. Latin America-Caribbean, Africa and Asia. This is particularly important for the IDC location procedure, as there are regions of the earth for which crustal models are not well constrained. For this purpose IDC has launched a RSTT initiative. In May 2012, a technical meeting was held in Vienna under the auspices of the CTBTO. The purpose of this meeting was to invite National Data Centre experts as well as network operators from Africa, Europe, the Middle East, Asia, Australia, Latin and North America to discuss the context under which a project to extend the RSTT model would be implemented. A total of 41 participants from 32 Member States

Study of attenuation structure for central Anatolia region, Turkey based on Keskin seismic array data

Science.gov (United States)

Semin, K. U.; Ozel, N. M.

2011-12-01

Central Anatolia is bounded in the north by the well-known north Anatolian fault system (NAFS) and on the south-southwest is bounded by the east Anatolian fault system (EAFS). The central area does not have major faults and acts as a single block moving westward. This region is not considered as seismically active as the NAFS or EAFS but the recent moderate-size Bala earthquakes (Ml=5.7, Ml= 5.5) on 20 and 27 December 2007 near the Tuz golu fault may be an indication of future seismic activity. In order to get a better picture of the crustal structure of this region we applied Coda Normalization method for the measurement of Qs-1 as a function of frequency for the frequencies 1.5, 3, 6, 8 Hz. 20 and 27 December 2007 Bala earthquakes (Ml magnitude 5.6 an 5.5) and their aftershocks recorded by the Keskin seismic array (International Monitoring System code BRTR) is analyzed in this study. Keskin seismic array has a small aperture circular design with 6 vertical short period and 1 broadband borehole seismometers. In addition, Multiple Lapse Time Window Analysis (MLTWA) method was applied to the data for the separation of intrinsic and scattering attenuation inm the region at the same frequencies. MLTWA method allowed a separation between the intrinsic attenuation and scattering attenuation. Preliminary results show a relatively low attenuation compared to western and eastern anatolia regions. This might be explained by the less seismicity in the region. A study of the regional and site attenuation of seismic waves of earthquakes in this area will contribute in predicting earthquake generated ground-motion and becomes vital in making decisions for earthquake regulations, building codes and to monitoring nuclear explosions.

Observations and modeling of seismic background noise

Science.gov (United States)

Peterson, Jon R.

1993-01-01

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

Toward uniform probabilistic seismic hazard assessments for Southeast Asia

Science.gov (United States)

Chan, C. H.; Wang, Y.; Shi, X.; Ornthammarath, T.; Warnitchai, P.; Kosuwan, S.; Thant, M.; Nguyen, P. H.; Nguyen, L. M.; Solidum, R., Jr.; Irsyam, M.; Hidayati, S.; Sieh, K.

2017-12-01

Although most Southeast Asian countries have seismic hazard maps, various methodologies and quality result in appreciable mismatches at national boundaries. We aim to conduct a uniform assessment across the region by through standardized earthquake and fault databases, ground-shaking scenarios, and regional hazard maps. Our earthquake database contains earthquake parameters obtained from global and national seismic networks, harmonized by removal of duplicate events and the use of moment magnitude. Our active-fault database includes fault parameters from previous studies and from the databases implemented for national seismic hazard maps. Another crucial input for seismic hazard assessment is proper evaluation of ground-shaking attenuation. Since few ground-motion prediction equations (GMPEs) have used local observations from this region, we evaluated attenuation by comparison of instrumental observations and felt intensities for recent earthquakes with predicted ground shaking from published GMPEs. We then utilize the best-fitting GMPEs and site conditions into our seismic hazard assessments. Based on the database and proper GMPEs, we have constructed regional probabilistic seismic hazard maps. The assessment shows highest seismic hazard levels near those faults with high slip rates, including the Sagaing Fault in central Myanmar, the Sumatran Fault in Sumatra, the Palu-Koro, Matano and Lawanopo Faults in Sulawesi, and the Philippine Fault across several islands of the Philippines. In addition, our assessment demonstrates the important fact that regions with low earthquake probability may well have a higher aggregate probability of future earthquakes, since they encompass much larger areas than the areas of high probability. The significant irony then is that in areas of low to moderate probability, where building codes are usually to provide less seismic resilience, seismic risk is likely to be greater. Infrastructural damage in East Malaysia during the 2015

Crustal seismicity and the earthquake catalog maximum moment magnitudes (Mcmax) in stable continental regions (SCRs): correlation with the seismic velocity of the lithosphere

Science.gov (United States)

Mooney, Walter D.; Ritsema, Jeroen; Hwang, Yong Keun

2012-01-01

A joint analysis of global seismicity and seismic tomography indicates that the seismic potential of continental intraplate regions is correlated with the seismic properties of the lithosphere. Archean and Early Proterozoic cratons with cold, stable continental lithospheric roots have fewer crustal earthquakes and a lower maximum earthquake catalog moment magnitude (Mcmax). The geographic distribution of thick lithospheric roots is inferred from the global seismic model S40RTS that displays shear-velocity perturbations (δVS) relative to the Preliminary Reference Earth Model (PREM). We compare δVS at a depth of 175 km with the locations and moment magnitudes (Mw) of intraplate earthquakes in the crust (Schulte and Mooney, 2005). Many intraplate earthquakes concentrate around the pronounced lateral gradients in lithospheric thickness that surround the cratons and few earthquakes occur within cratonic interiors. Globally, 27% of stable continental lithosphere is underlain by δVS≥3.0%, yet only 6.5% of crustal earthquakes with Mw>4.5 occur above these regions with thick lithosphere. No earthquakes in our catalog with Mw>6 have occurred above mantle lithosphere with δVS>3.5%, although such lithosphere comprises 19% of stable continental regions. Thus, for cratonic interiors with seismically determined thick lithosphere (1) there is a significant decrease in the number of crustal earthquakes, and (2) the maximum moment magnitude found in the earthquake catalog is Mcmax=6.0. We attribute these observations to higher lithospheric strength beneath cratonic interiors due to lower temperatures and dehydration in both the lower crust and the highly depleted lithospheric root.

Crustal seismicity and the earthquake catalog maximum moment magnitude (Mcmax) in stable continental regions (SCRs): Correlation with the seismic velocity of the lithosphere

Science.gov (United States)

Mooney, Walter D.; Ritsema, Jeroen; Hwang, Yong Keun

2012-12-01

A joint analysis of global seismicity and seismic tomography indicates that the seismic potential of continental intraplate regions is correlated with the seismic properties of the lithosphere. Archean and Early Proterozoic cratons with cold, stable continental lithospheric roots have fewer crustal earthquakes and a lower maximum earthquake catalog moment magnitude (Mcmax). The geographic distribution of thick lithospheric roots is inferred from the global seismic model S40RTS that displays shear-velocity perturbations (δVS) relative to the Preliminary Reference Earth Model (PREM). We compare δVS at a depth of 175 km with the locations and moment magnitudes (Mw) of intraplate earthquakes in the crust (Schulte and Mooney, 2005). Many intraplate earthquakes concentrate around the pronounced lateral gradients in lithospheric thickness that surround the cratons and few earthquakes occur within cratonic interiors. Globally, 27% of stable continental lithosphere is underlain by δVS≥3.0%, yet only 6.5% of crustal earthquakes with Mw>4.5 occur above these regions with thick lithosphere. No earthquakes in our catalog with Mw>6 have occurred above mantle lithosphere with δVS>3.5%, although such lithosphere comprises 19% of stable continental regions. Thus, for cratonic interiors with seismically determined thick lithosphere (1) there is a significant decrease in the number of crustal earthquakes, and (2) the maximum moment magnitude found in the earthquake catalog is Mcmax=6.0. We attribute these observations to higher lithospheric strength beneath cratonic interiors due to lower temperatures and dehydration in both the lower crust and the highly depleted lithospheric root.

Contribution of the Surface and Down-Hole Seismic Networks to the Location of Earthquakes at the Soultz-sous-Forêts Geothermal Site (France)

Science.gov (United States)

Kinnaert, X.; Gaucher, E.; Kohl, T.; Achauer, U.

2018-03-01

Seismicity induced in geo-reservoirs can be a valuable observation to image fractured reservoirs, to characterize hydrological properties, or to mitigate seismic hazard. However, this requires accurate location of the seismicity, which is nowadays an important seismological task in reservoir engineering. The earthquake location (determination of the hypocentres) depends on the model used to represent the medium in which the seismic waves propagate and on the seismic monitoring network. In this work, location uncertainties and location inaccuracies are modeled to investigate the impact of several parameters on the determination of the hypocentres: the picking uncertainty, the numerical precision of picked arrival times, a velocity perturbation and the seismic network configuration. The method is applied to the geothermal site of Soultz-sous-Forêts, which is located in the Upper Rhine Graben (France) and which was subject to detailed scientific investigations. We focus on a massive water injection performed in the year 2000 to enhance the productivity of the well GPK2 in the granitic basement, at approximately 5 km depth, and which induced more than 7000 earthquakes recorded by down-hole and surface seismic networks. We compare the location errors obtained from the joint or the separate use of the down-hole and surface networks. Besides the quantification of location uncertainties caused by picking uncertainties, the impact of the numerical precision of the picked arrival times as provided in a reference catalogue is investigated. The velocity model is also modified to mimic possible effects of a massive water injection and to evaluate its impact on earthquake hypocentres. It is shown that the use of the down-hole network in addition to the surface network provides smaller location uncertainties but can also lead to larger inaccuracies. Hence, location uncertainties would not be well representative of the location errors and interpretation of the seismicity

Swedish National Seismic Network (SNSN). A short report on recorded earthquakes during the fourth quarter of the year 2010

Energy Technology Data Exchange (ETDEWEB)

Boedvarsson, Reynir (Uppsala Univ. (Sweden), Dept. of Earth Sciences)

2011-01-15

According to an agreement with Swedish Nuclear Fuel and Waste Management Company (SKB) and Uppsala Univ., the Dept. of Earth Sciences has continued to carry out observations of seismic events at seismic stations within the Swedish National Seismic Network (SNSN). This short report gives brief information about the recorded seismicity during October through December 2010. The Swedish National Seismic Network consists of 62 stations. During October through December, 2,241 events were located whereof 158 are estimated as real earthquakes, 1,457 are estimated as explosions, 444 are induced earthquakes in the vicinity of the mines in Kiruna and Malmberget and 182 events are still considered as uncertain but these are most likely explosions and are mainly located outside the network. One earthquake had a magnitude above M{sub L} = 2.0 during the period. In November one earthquake was located 13 km SW of Haernoesand with a magnitude of M{sub L} = 2.1. The largest earthquake in October had a magnitude of M{sub L} = 1.7 and was located 12 km NE of Eksjoe and in December an earthquake with a magnitude of M{sub L} = 1.8 was located 19 km north of Motala

Seismological database for Banat seismic region (Romania) - Part 1: The parametric earthquake catalogue

International Nuclear Information System (INIS)

Oros, E.; Popa, M.; Moldovan, I. A.

2008-01-01

The most comprehensive seismological database for Banat seismic region (Romania) has been achieved. This paper refers to the essential characteristics of the first component of this database, namely the Parametric Earthquakes Catalogue for the Banat Seismic Region (PECBSR). PECBSR comprises 7783 crustal earthquakes (3 ≤ h ≤ 25 km) with 0.4 ≤ M i ≥ 5.6 (M i is M L , M D , M S , M W , Mm and/or mb from compiled sources) occurred in the Banat region and its surroundings between years 1443 and 2006. Different magnitude scales were converted into moment magnitude scale, Mw. The completeness of PECBSR strongly depends on the time. (authors)

Recent developments in seismic seabed oil reservoir monitoring applications using fibre-optic sensing networks

International Nuclear Information System (INIS)

De Freitas, J M

2011-01-01

This review looks at recent developments in seismic seabed oil reservoir monitoring techniques using fibre-optic sensing networks. After a brief introduction covering the background and scope of the review, the following section focuses on state-of-the-art fibre-optic hydrophones and accelerometers used for seismic applications. Related metrology aspects of the sensor such as measurement of sensitivity, noise and cross-axis performance are addressed. The third section focuses on interrogation systems. Two main phase-based competing systems have emerged over the past two decades for seismic applications, with a third technique showing much promise; these have been compared in terms of general performance. (topical review)

Automation of seismic network signal interpolation: an artificial intelligence approach

International Nuclear Information System (INIS)

Chiaruttini, C.; Roberto, V.

1988-01-01

After discussing the current status of the automation in signal interpretation from seismic networks, a new approach, based on artificial-intelligence tecniques, is proposed. The knowledge of the human expert analyst is examined, with emphasis on its objects, strategies and reasoning techniques. It is argued that knowledge-based systems (or expert systems) provide the most appropriate tools for designing an automatic system, modelled on the expert behaviour

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.

Thermal regime of the lithosphere and prediction of seismic hazard in the Caspian region

International Nuclear Information System (INIS)

Levin, L.E.; Solodilov, L.N.; Kondorskaya, N.V.; Gasanov, A.G; Panahi, B.M.

2002-01-01

Full text : Prediction of seicmicity is one of elements of ecology hazard warning. In this collective research, it is elaborated in three directions : quantitative estimate of regional faults by level of seismic activity; ascertainment of space position of earthquake risk zones, determination of high seismic potential sites for the period of the next 3-5 years. During elaboration of prediction, it takes into account that peculiar feature all over the is determined by relationship of about 90 percent of earthquake hypocenters and released energy of seismic waves with elactic-brittle ayer of the lithosphere. Concetration of earthquakes epicenters is established predominantly in zones of complex structure of elastic-brittle layer where gradient of it thickness is 20-30 km. Directions of hypocenters migration in the plastic-viscous layer reveal a space position of seismic dangerous zones. All this provides a necessity for generalization of data on location of earthquakes epicenters; determination of their magnitudes, space position of regional faults and heat flow with calculation of thermal regime being made for clarification of the lithosphere and elastic-brittle thickness variations separately. General analysis includes a calculation of released seismic wave energy and determination of peculiar features of its distribution in the entire region and also studies of hypocenters migration in the plastic-viscous layer of the litosphere in time.

Third Quarter Hanford Seismic Report for Fiscal Year 2008

Energy Technology Data Exchange (ETDEWEB)

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

2008-09-01

The 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 Hanford Seismic Assessment Team locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, natural phenomena hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of 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. For the Hanford Seismic Network, fourteen local earthquakes were recorded during the third quarter of fiscal year 2008. The largest event recorded by the network during the third quarter (May 18, 2008 - magnitude 3.7 Mc) was located approximately 17 km east of Prosser at a depth of 20.5 km. With regard to the depth distribution, five earthquakes occurred at shallow depths (less than 4 km, most likely in the Columbia River basalts), six 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 crystalline basement. Geographically, eight earthquakes occurred in swarm areas and six earthquakes were classified as random events. The largest event recorded by the network during the third quarter occurred on May 18 (magnitude 3.7 Mc) and was located approximately 17 km east of Prosser at a depth of 20.5 km. This earthquake was the highest magnitude event recorded in the 46-47 N. latitude / 119-120 W. longitude sector since 1975

Detection and localization capability of an urban seismic sinkhole monitoring network

Science.gov (United States)

Becker, Dirk; Dahm, Torsten; Schneider, Fabian

2017-04-01

Microseismic events linked to underground processes in sinkhole areas might serve as precursors to larger mass dislocation or rupture events which can cause felt ground shaking or even structural damage. To identify these weak and shallow events, a sensitive local seismic monitoring network is needed. In case of an urban environment the performance of local monitoring networks is severely compromised by the high anthropogenic noise level. We study the detection and localization capability of such a network, which is already partly installed in the urban area of the city of Hamburg, Germany, within the joint project SIMULTAN (http://www.gfz-potsdam.de/en/section/near-surface-geophysics/projects/simultan/). SIMULTAN aims to monitor a known sinkhole structure and gain a better understanding of the underlying processes. The current network consists of six surface stations installed in the basement of private houses and underground structures of a research facility (DESY - Deutsches Elektronen Synchrotron). During the started monitoring campaign since 2015, no microseismic events could be unambiguously attributed to the sinkholes. To estimate the detection and location capability of the network, we calculate synthetic waveforms based on the location and mechanism of former events in the area. These waveforms are combined with the recorded urban seismic noise at the station sites. As detection algorithms a simple STA/LTA trigger and a more sophisticated phase detector are used. While the STA/LTA detector delivers stable results and is able to detect events with a moment magnitude as low as 0.35 at a distance of 1.3km from the source even under the present high noise conditions the phase detector is more sensitive but also less stable. It should be stressed that due to the local near surface conditions of the wave propagation the detections are generally performed on S- or surface waves and not on P-waves, which have a significantly lower amplitude. Due to the often

Recent crustal movements and seismicity in the western coastal region of peninsular India

Science.gov (United States)

Kailasam, L. N.

1983-09-01

Recent crustal movements, tectonics and seismicity of the western coastal region of peninsular India have been studied in detail in the very recent past. Prominent geomorphic features and large-scale manifestation of Holocene deformation and crustal movements have been noticed and studied over this coastal region from the Gulf of Cambay to the southernmost parts of Kerala, evidence for which is afforded in the form of Recent and sub-Recent raised beaches, sandbars, raised old terraces, pebble beds, etc. The sedimentary formations in this narrow coastal belt include Neogene and Quaternary sediments. The Bouguer gravity map of the western coastal tract shows some prominent gravity features extending into the offshore regions, suggestive of some significant tectonic and structural features. The seismic data in the offshore regions bring out some prominent roughly northwest-southeast as well as east-west faults and shears, in addition to prominent structural "highs" off the Bombay and Ratnagiri coast which have proved oil. The seismicity in this coastal tract as well as the faulted western margin of the western continental shelf in the Arabian Sea is generally of magnitude 3-6.

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

Energy Technology Data Exchange (ETDEWEB)

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

1997-05-01

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

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

International Nuclear Information System (INIS)

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

1997-05-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1998-06-01

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

Seismic facies; Facies sismicas

Energy Technology Data Exchange (ETDEWEB)

Johann, Paulo Roberto Schroeder [PETROBRAS, Rio de Janeiro, RJ (Brazil). Exploracao e Producao Corporativo. Gerencia de Reservas e Reservatorios]. E-mail: johann@petrobras.com.br

2004-11-01

The method presented herein describes the seismic facies as representations of curves and vertical matrixes of the lithotypes proportions. The seismic facies are greatly interested in capturing the spatial distributions (3D) of regionalized variables, as for example, lithotypes, sedimentary facies groups and/ or porosity and/or other properties of the reservoirs and integrate them into the 3D geological modeling (Johann, 1997). Thus when interpreted as curves or vertical matrixes of proportions, seismic facies allow us to build a very important tool for structural analysis of regionalized variables. The matrixes have an important application in geostatistical modeling. In addition, this approach provides results about the depth and scale of the wells profiles, that is, seismic data is integrated to the characterization of reservoirs in depth maps and in high resolution maps. The link between the different necessary technical phases involved in the classification of the segments of seismic traces is described herein in groups of predefined traces of two approaches: a) not supervised and b) supervised by the geological knowledge available on the studied reservoir. The multivariate statistical methods used to obtain the maps of the seismic facies units are interesting tools to be used to provide a lithostratigraphic and petrophysical understanding of a petroleum reservoir. In the case studied these seismic facies units are interpreted as representative of the depositional system as a part of the Namorado Turbiditic System, Namorado Field, Campos Basin.Within the scope of PRAVAP 19 (Programa Estrategico de Recuperacao Avancada de Petroleo - Strategic Program of Advanced Petroleum Recovery) some research work on algorithms is underway to select new optimized attributes to apply seismic facies. One example is the extraction of attributes based on the wavelet transformation and on the time-frequency analysis methodology. PRAVAP is also carrying out research work on an

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

OpenAIRE

Kværna, Tormod; Gibbons, Steven; Mykkeltveit, Svein

2017-01-01

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

MyShake - Smartphone seismic network powered by citizen scientists

Science.gov (United States)

Kong, Q.; Allen, R. M.; Schreier, L.; Strauss, J. A.

2017-12-01

MyShake is a global smartphone seismic network that harnesses the power of crowdsourcing. It is driven by the citizen scientists that run MyShake on their personal smartphones. It has two components: an android application running on the smartphones to detect earthquake-like motion, and a network detection algorithm to aggregate results from multiple smartphones to confirm when an earthquake occurs. The MyShake application was released to the public on Feb 12th 2016. Within the first year, more than 250,000 people downloaded MyShake app around the world. There are more than 500 earthquakes recorded by the smartphones in this period, including events in Chile, Argentina, Mexico, Morocco, Greece, Nepal, New Zealand, Taiwan, Japan, and across North America. Currently, we are working on earthquake early warning with MyShake network and the shaking data provided by MyShake is a unique dataset that can be used for the research community.

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.

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

Science.gov (United States)

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

2002-12-01

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

Fault specific GIS based seismic hazard maps for the Attica region, Greece

Science.gov (United States)

Deligiannakis, G.; Papanikolaou, I. D.; Roberts, G.

2018-04-01

Traditional seismic hazard assessment methods are based on the historical seismic records for the calculation of an annual probability of exceedance for a particular ground motion level. A new fault-specific seismic hazard assessment method is presented, in order to address problems related to the incompleteness and the inhomogeneity of the historical records and to obtain higher spatial resolution of hazard. This method is applied to the region of Attica, which is the most densely populated area in Greece, as nearly half of the country's population lives in Athens and its surrounding suburbs, in the Greater Athens area. The methodology is based on a database of 24 active faults that could cause damage to Attica in case of seismic rupture. This database provides information about the faults slip rates, lengths and expected magnitudes. The final output of the method is four fault-specific seismic hazard maps, showing the recurrence of expected intensities for each locality. These maps offer a high spatial resolution, as they consider the surface geology. Despite the fact that almost half of the Attica region lies on the lowest seismic risk zone according to the official seismic hazard zonation of Greece, different localities have repeatedly experienced strong ground motions during the last 15 kyrs. Moreover, the maximum recurrence for each intensity occurs in different localities across Attica. Highest recurrence for intensity VII (151-156 times over 15 kyrs, or up to a 96 year return period) is observed in the central part of the Athens basin. The maximum intensity VIII recurrence (115 times over 15 kyrs, or up to a 130 year return period) is observed in the western part of Attica, while the maximum intensity IX (73-77/15 kyrs, or a 195 year return period) and X (25-29/15 kyrs, or a 517 year return period) recurrences are observed near the South Alkyonides fault system, which dominates the strong ground motions hazard in the western part of the Attica mainland.

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

Science.gov (United States)

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

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

Composite Earthquake Catalog of the Yellow Sea for Seismic Hazard Studies

Science.gov (United States)

Kang, S. Y.; Kim, K. H.; LI, Z.; Hao, T.

2017-12-01

The Yellow Sea (a.k.a West Sea in Korea) is an epicontinental and semi-closed sea located between Korea and China. Recent earthquakes in the Yellow Sea including, but not limited to, the Seogyuckryulbi-do (1 April 2014, magnitude 5.1), Heuksan-do (21 April 2013, magnitude 4.9), Baekryung-do (18 May 2013, magnitude 4.9) earthquakes, and the earthquake swarm in the Boryung offshore region in 2013, remind us of the seismic hazards affecting east Asia. This series of earthquakes in the Yellow Sea raised numerous questions. Unfortunately, both governments have trouble in monitoring seismicity in the Yellow Sea because earthquakes occur beyond their seismic networks. For example, the epicenters of the magnitude 5.1 earthquake in the Seogyuckryulbi-do region in 2014 reported by the Korea Meteorological Administration and China Earthquake Administration differed by approximately 20 km. This illustrates the difficulty with seismic monitoring and locating earthquakes in the region, despite the huge effort made by both governments. Joint effort is required not only to overcome the limits posed by political boundaries and geographical location but also to study seismicity and the underground structures responsible. Although the well-established and developing seismic networks in Korea and China have provided unprecedented amount and quality of seismic data, high quality catalog is limited to the recent 10s of years, which is far from major earthquake cycle. It is also noticed the earthquake catalog from either country is biased to its own and cannot provide complete picture of seismicity in the Yellow Sea. In order to understand seismic hazard and tectonics in the Yellow Sea, a composite earthquake catalog has been developed. We gathered earthquake information during last 5,000 years from various sources. There are good reasons to believe that some listings account for same earthquake, but in different source parameters. We established criteria in order to provide consistent

Exploiting IoT Technologies and Open Source Components for Smart Seismic Network Instrumentation

Science.gov (United States)

Germenis, N. G.; Koulamas, C. A.; Foundas, P. N.

2017-12-01

The data collection infrastructure of any seismic network poses a number of requirements and trade-offs related to accuracy, reliability, power autonomy and installation & operational costs. Having the right hardware design at the edge of this infrastructure, embedded software running inside the instruments is the heart of pre-processing and communication services implementation and their integration with the central storage and processing facilities of the seismic network. This work demonstrates the feasibility and benefits of exploiting software components from heterogeneous sources in order to realize a smart seismic data logger, achieving higher reliability, faster integration and less development and testing costs of critical functionality that is in turn responsible for the cost and power efficient operation of the device. The instrument's software builds on top of widely used open source components around the Linux kernel with real-time extensions, the core Debian Linux distribution, the earthworm and seiscomp tooling frameworks, as well as components from the Internet of Things (IoT) world, such as the CoAP and MQTT protocols for the signaling planes, besides the widely used de-facto standards of the application domain at the data plane, such as the SeedLink protocol. By using an innovative integration of features based on lower level GPL components of the seiscomp suite with higher level processing earthworm components, coupled with IoT protocol extensions to the latter, the instrument can implement smart functionality such as network controlled, event triggered data transmission in parallel with edge archiving and on demand, short term historical data retrieval.

RAPID DETERMINATION OF FOCAL DEPTH USING A GLOBAL NETWORK OF SMALL-APERTURE SEISMIC ARRAYS

Science.gov (United States)

Seats, K.; Koper, K.; Benz, H.

2009-12-01

The National Earthquake Information Center (NEIC) of the United States Geological Survey (USGS) operates 24 hours a day, 365 days a year with the mission of locating and characterizing seismic events around the world. A key component of this task is quickly determining the focal depth of each seismic event, which has a first-order effect on estimates of ground shaking used in the impact assessment applications of emergency response activities. Current methods of depth estimation used at the NEIC include arrival time inversion both with and without depth phases, a Bayesian depth constraint based on historical seismicity (1973-present), and moment tensor inversion primarily using P- and S-wave waveforms. In this study, we explore the possibility of automated modeling of waveforms from vertical-component arrays of the International Monitoring System (IMS) to improve rapid depth estimation at NEIC. Because these arrays are small-aperture, they are effective at increasing signal to noise ratios for frequencies of 1 Hz and higher. Currently, NEIC receives continuous real-time data from 23 IMS arrays. Following work done by previous researchers, we developed a technique that acts as an array of arrays. For a given epicentral location we calculate fourth root beams for each IMS array in the distance range of 30 to 95 degrees at the expected slowness vector of the first arrival. Because the IMS arrays are small-aperture, these beams highlight energy that has slowness similar to the first arrival, such as depth phases. The beams are rectified by taking the envelope and then automatically aligned on the largest peak within 5 seconds of the expected arrival time. The station beams are then combined into network beams assuming a range of depths varying from 10 km to 700 km in increments of 1 km. The network beams are computed assuming both pP and sP propagation, and a measure of beam power is output as a function of depth for both propagation models, as well as their sum. We

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

Energy Technology Data Exchange (ETDEWEB)

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

1997-08-01

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

Probabilistic Seismic Hazard Assessment for Himalayan-Tibetan Region from Historical and Instrumental Earthquake Catalogs

Science.gov (United States)

Rahman, M. Moklesur; Bai, Ling; Khan, Nangyal Ghani; Li, Guohui

2018-02-01

The Himalayan-Tibetan region has a long history of devastating earthquakes with wide-spread casualties and socio-economic damages. Here, we conduct the probabilistic seismic hazard analysis by incorporating the incomplete historical earthquake records along with the instrumental earthquake catalogs for the Himalayan-Tibetan region. Historical earthquake records back to more than 1000 years ago and an updated, homogenized and declustered instrumental earthquake catalog since 1906 are utilized. The essential seismicity parameters, namely, the mean seismicity rate γ, the Gutenberg-Richter b value, and the maximum expected magnitude M max are estimated using the maximum likelihood algorithm assuming the incompleteness of the catalog. To compute the hazard value, three seismogenic source models (smoothed gridded, linear, and areal sources) and two sets of ground motion prediction equations are combined by means of a logic tree on accounting the epistemic uncertainties. The peak ground acceleration (PGA) and spectral acceleration (SA) at 0.2 and 1.0 s are predicted for 2 and 10% probabilities of exceedance over 50 years assuming bedrock condition. The resulting PGA and SA maps show a significant spatio-temporal variation in the hazard values. In general, hazard value is found to be much higher than the previous studies for regions, where great earthquakes have actually occurred. The use of the historical and instrumental earthquake catalogs in combination of multiple seismogenic source models provides better seismic hazard constraints for the Himalayan-Tibetan region.

The Crustal Structure and Seismicity of Eastern Venezuela

Science.gov (United States)

Schmitz, M.; Martins, A.; Sobiesiak, M.; Alvarado, L.; Vasquez, R.

2001-12-01

Eastern Venezuela is characterized by a moderate to high seismicity, evidenced recently by the 1997 Cariaco earthquake located on the El Pilar Fault, a right lateral strike slip fault which marks the plate boundary between the Caribbean and South-American plates in this region. Recently, the seismic activity seems to migrate towards the zone of subduction of the Lesser Antilles in the northeast, where a mb 6.0 earthquake occurred in October 2000 at 120 km of depth. Periodical changes in the seismic activity are related to the interaction of the stress fields of the strike-slip and the subduction regimes. The seismic activity decreases rapidly towards to the south with some disperse events on the northern edge of the Guayana Shield, related to the Guri fault system. The crustal models used in the region are derived from the information generated by the national seismological network since 1982 and by microseismicity studies in northeastern Venezuela, coinciding in a crustal thickness of about 35 km in depth. Results of seismic refraction measurements for the region were obtained during field campains in 1998 (ECOGUAY) for the Guayana Shield and the Cariaco sedimentary basin and in 2001 (ECCO) for the Oriental Basin. The total crustal thickness decreases from about 45 km on the northern edge of the Guayana Shield to some 36 km close to El Tigre in the center of the Oriental Basin. The average crustal velocity decreases in the same sense from 6.5 to 5.8 km/s. In the Cariaco sedimentary basin a young sedimentary cover of 1 km thickness with a seismic velocity of 2 km/s was derived. Towards the northern limit of the South-American plate, no deep seismic refraction data are available up to now. The improvement of the crustal models used in that region would constitute a step forward in the analysis of the seismic hazard. Seismic refraction studies funded by CONICIT S1-97002996 and S1-2000000685 projects and PDVSA (additional drilling and blasting), recording equipment

An alternative approach to probabilistic seismic hazard analysis in the Aegean region using Monte Carlo simulation

Science.gov (United States)

Weatherill, Graeme; Burton, Paul W.

2010-09-01

The Aegean is the most seismically active and tectonically complex region in Europe. Damaging earthquakes have occurred here throughout recorded history, often resulting in considerable loss of life. The Monte Carlo method of probabilistic seismic hazard analysis (PSHA) is used to determine the level of ground motion likely to be exceeded in a given time period. Multiple random simulations of seismicity are generated to calculate, directly, the ground motion for a given site. Within the seismic hazard analysis we explore the impact of different seismic source models, incorporating both uniform zones and distributed seismicity. A new, simplified, seismic source model, derived from seismotectonic interpretation, is presented for the Aegean region. This is combined into the epistemic uncertainty analysis alongside existing source models for the region, and models derived by a K-means cluster analysis approach. Seismic source models derived using the K-means approach offer a degree of objectivity and reproducibility into the otherwise subjective approach of delineating seismic sources using expert judgment. Similar review and analysis is undertaken for the selection of peak ground acceleration (PGA) attenuation models, incorporating into the epistemic analysis Greek-specific models, European models and a Next Generation Attenuation model. Hazard maps for PGA on a "rock" site with a 10% probability of being exceeded in 50 years are produced and different source and attenuation models are compared. These indicate that Greek-specific attenuation models, with their smaller aleatory variability terms, produce lower PGA hazard, whilst recent European models and Next Generation Attenuation (NGA) model produce similar results. The Monte Carlo method is extended further to assimilate epistemic uncertainty into the hazard calculation, thus integrating across several appropriate source and PGA attenuation models. Site condition and fault-type are also integrated into the hazard

Neural net generated seismic facies map and attribute facies map

International Nuclear Information System (INIS)

Addy, S.K.; Neri, P.

1998-01-01

The usefulness of 'seismic facies maps' in the analysis of an Upper Wilcox channel system in a 3-D survey shot by CGG in 1995 in Lavaca county in south Texas was discussed. A neural net-generated seismic facies map is a quick hydrocarbon exploration tool that can be applied regionally as well as on a prospect scale. The new technology is used to classify a constant interval parallel to a horizon in a 3-D seismic volume based on the shape of the wiggle traces using a neural network technology. The tool makes it possible to interpret sedimentary features of a petroleum deposit. The same technology can be used in regional mapping by making 'attribute facies maps' in which various forms of amplitude attributes, phase attributes or frequency attributes can be used

Puerto Rico Seismic Network Operations During and After the Hurricane Maria: Response, Continuity of Operations, and Experiences

Science.gov (United States)

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

2017-12-01

The Puerto Rico Seismic Network (PRSN) is an integral part of earthquake and tsunami monitoring in Puerto Rico and the Virgin Islands. The PRSN conducts scientific research as part of the University of Puerto Rico Mayaguez, conducts the earthquake monitoring for the region, runs extensive earthquake and tsunami education and outreach programs, and acts as a Tsunami Warning Focal Point Alternate for Puerto Rico. During and in the immediate aftermath of Hurricane Maria, the PRSN duties and responsibilities evolved from a seismic network to a major information and communications center for the western side of Puerto Rico. Hurricane Maria effectively destroyed most communications on island, critically between the eastern side of the island where Puerto Rico's Emergency Management's (PREMA) main office and the National Weather Service (NWS) is based and the western side of the island. Additionally, many local emergency management agencies on the western side of the island lost a satellite based emergency management information system called EMWIN which provides critical tsunami and weather information. PRSN's EMWIN system remained functional and consequently via this system and radio communications PRSN became the only information source for NWS warnings and bulletins, tsunami alerts, and earthquake information for western Puerto Rico. Additionally, given the functional radio and geographic location of the PRSN, the network became a critical communications relay for local emergency management. Here we will present the PRSN response in relation to Hurricane Maria including the activation of the PRSN devolution plan, adoption of duties, experiences and lessons learned for continuity of operations and adoption of responsibilities during future catastrophic events.

Data Delivery Latency Improvements And First Steps Towards The Distributed Computing Of The Caltech/USGS Southern California Seismic Network Earthquake Early Warning System

Science.gov (United States)

Stubailo, I.; Watkins, M.; Devora, A.; Bhadha, R. J.; Hauksson, E.; Thomas, V. I.

2016-12-01

The USGS/Caltech Southern California Seismic Network (SCSN) is a modern digital ground motion seismic network. It develops and maintains Earthquake Early Warning (EEW) data collection and delivery systems in southern California as well as real-time EEW algorithms. Recently, Behr et al., SRL, 2016 analyzed data from several regional seismic networks deployed around the globe. They showed that the SCSN was the network with the smallest data communication delays or latency. Since then, we have reduced further the telemetry delays for many of the 330 current sites. The latency has been reduced on average from 2-6 sec to 0.4 seconds by tuning the datalogger parameters and/or deploying software upgrades. Recognizing the latency data as one of the crucial parameters in EEW, we have started archiving the per-packet latencies in mseed format for all the participating sites in a similar way it is traditionally done for the seismic waveform data. The archived latency values enable us to understand and document long-term changes in performance of the telemetry links. We can also retroactively investigate how latent the waveform data were during a specific event or during a specific time period. In addition the near-real time latency values are useful for monitoring and displaying the real-time station latency, in particular to compare different telemetry technologies. A future step to reduce the latency is to deploy the algorithms on the dataloggers at the seismic stations and transmit either the final solutions or intermediate parameters to a central processing center. To implement this approach, we are developing a stand-alone version of the OnSite algorithm to run on the dataloggers in the field. This will increase the resiliency of the SCSN to potential telemetry restrictions in the immediate aftermath of a large earthquake, either by allowing local alarming by the single station, or permitting transmission of lightweight parametric information rather than continuous

Geo-Proxy-Based Site Classification for Regional Zonation of Seismic Site Effects in South Korea

Directory of Open Access Journals (Sweden)

Chang-Guk Sun

2018-02-01

Full Text Available Seismic site effects and topographic effects related to ground motion occur during an earthquake due to site-specific geotechnical or geological characteristics, including the geological or geographical structure and the characteristics of near-surface sub-soil layers. Site-specific site effects due to geological conditions have been confirmed in recent earthquake events. Earthquake-induced damage has mainly occurred at accumulated soft soil layers under basins or along coasts and rivers. An alternative method has recently been proposed for evaluating regional seismic site effects and amplification factors using digital elevation models (DEM. High-quality DEMs at high resolutions may be employed to resolve finer-scale variations in topographic gradients and consequently, correlated site response parameters. Because there are many regions in South Korea lacking borehole datasets, which are insufficient for site classification only using borehole datasets, a DEM-based proxy for seismic zonation can be effective. Thus, in this study, geo-proxy-based site classification was proposed based on empirical correlations with site response parameters and conducted for regional zonation of seismic site effects to identify the amplification of characteristics in the western metropolitan areas of South Korea, depending on the site-specific geo-spatial conditions.

Seismic Observations in the Taipei Metropolitan Area Using the Downhole Network

Directory of Open Access Journals (Sweden)

Win-Gee Huang

2010-01-01

Full Text Available Underlain by soft soils, the Taipei Metropolitan Area (TMA experienced major damage due to ground-motion amplification during the Hualien earthquake of 1986, the Chi-Chi earthquake of 1999, the Hualien earthquake of 2002 and the Taitung earthquake of 2003. To study how a local site can substantially change the characteristics of seismic waves as they pass through soft deposits below the free surface, two complementary downhole seismic arrays have been operated in the TMA, since 1991 and 2008. The accelerometer downhole array is composed of eight boreholes at depths in excess of 300 meters. The downhole array velocity sensor collocated with accelerometer composed of four boreholes at depths up to 90 meters. The integrated seismic network monitors potential earthquakes originating from faults in and around the TMA and provides wide-dynamic range measurement of data ranging in amplitude from seismic background noise levels to damage levels as a result of shaking. The data sets can be used to address on the response of soft-soil deposits to ground motions. One of the major considerations is the nonlinear response of soft soil deposits at different levels of excitation. The collocated acceloerometer and velocity sensors at boreholes give the necessary data for studies of non-linearity to be acquired. Such measurements in anticipation of future large, damaging earthquakes will be of special importance for the mitigation of earthquake losses.

Earthquake Complex Network applied along the Chilean Subduction Zone.

Science.gov (United States)

Martin, F.; Pasten, D.; Comte, D.

2017-12-01

In recent years the earthquake complex networks have been used as a useful tool to describe and characterize the behavior of seismicity. The earthquake complex network is built in space, dividing the three dimensional space in cubic cells. If the cubic cell contains a hypocenter, we call this cell like a node. The connections between nodes follows the time sequence of the occurrence of the seismic events. In this sense, we have a spatio-temporal configuration of a specific region using the seismicity in that zone. In this work, we are applying complex networks to characterize the subduction zone along the coast of Chile using two networks: a directed and an undirected network. The directed network takes in consideration the time-direction of the connections, that is very important for the connectivity of the network: we are considering the connectivity, ki of the i-th node, like the number of connections going out from the node i and we add the self-connections (if two seismic events occurred successive in time in the same cubic cell, we have a self-connection). The undirected network is the result of remove the direction of the connections and the self-connections from the directed network. These two networks were building using seismic data events recorded by CSN (Chilean Seismological Center) in Chile. This analysis includes the last largest earthquakes occurred in Iquique (April 2014) and in Illapel (September 2015). The result for the directed network shows a change in the value of the critical exponent along the Chilean coast. The result for the undirected network shows a small-world behavior without important changes in the topology of the network. Therefore, the complex network analysis shows a new form to characterize the Chilean subduction zone with a simple method that could be compared with another methods to obtain more details about the behavior of the seismicity in this region.

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

In-situ measurements of seismic velocities in the San Francisco Bay Region; part III

Science.gov (United States)

Gibbs, James F.; Fumal, Thomas E.; Borcherdt, Roger D.; Roth, Edward F.

1977-01-01

Seismic wave velocities (compressional and shear) are important parameters for estimating the seismic response characteristics of various geologic units when subjected to strong earthquake ground shaking. Seismic velocities of various units often show a strong correlation with the amounts of damage following large earthquakes and have been used as a basis for certain types of seismic zonation studies. In the current program seismic velocities have been measured at 59 locations 1n the San Francisco Bay Region. This report is the third in a series of Open-File Reports and describes the in-situ velocity measurements at locations 35-59. At each location seismic travel times are measured in drill holes, normally at 2.5-m intervals to a depth of 30 m. Geologic logs are determined from drill cuttings, undisturbed (cored) samples, and penetrometer samples. The data provide a detailed comparison of geologic and seismic characteristics and provide parameters for estimating strong earthquake ground motions quantitatively at each of the sites. A major emphasis of this program is to obtain a detailed comparison of geologic and seismic data on a regional scale for use in seismic zonation. There is a variety of geologic and seismic data available in the San Francisco Bay Region for use 1n developing the general zoning techniques which can then be applied to other areas. Shear wave velocities 1n near-surface geologic materials are of especial interest for engineering seismology and seismic zonation studies, yet in general, they are difficult to measure because of contamination by compressional waves. A comparison of various in-situ techniques by Warrick (1974) establishes the reliability of the method utilizing a "horizontal traction" source for sites underlain by bay mud and alluvium. Gibbs, and others (1975a) present data from 12 holes and establishes the reliability of the method for sites underlain by a variety of different rock units and suggest extending the measurements to

First Quarter Hanford Seismic Report for Fiscal Year 1999

Energy Technology Data Exchange (ETDEWEB)

DC Hartshorn; SP Reidel; AC Rohay

1999-05-26

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

Resistivity and Seismic Surface Wave Tomography Results for the Nevşehir Kale Region: Cappadocia, Turkey

Science.gov (United States)

Coşkun, Nart; Çakır, Özcan; Erduran, Murat; Arif Kutlu, Yusuf

2014-05-01

The Nevşehir Kale region located in the middle of Cappadocia with approximately cone shape is investigated for existence of an underground city using the geophysical methods of electrical resistivity and seismic surface wave tomography together. Underground cities are generally known to exist in Cappadocia. The current study has obtained important clues that there may be another one under the Nevşehir Kale region. Two-dimensional resistivity and seismic profiles approximately 4-km long surrounding the Nevşehir Kale are measured to determine the distribution of electrical resistivities and seismic velocities under the profiles. Several high resistivity anomalies with a depth range 8-20 m are discovered to associate with a systematic void structure beneath the region. Because of the high resolution resistivity measurement system currently employed we were able to isolate the void structure from the embedding structure. Low seismic velocity zones associated with the high resistivity depths are also discovered. Using three-dimensional visualization techniques we show the extension of the void structure under the measured profiles.

Kinematics and Seismotectonics of the Montello Thrust Fault (Southeastern Alps, Italy) Revealed by Local GPS and Seismic Networks

Science.gov (United States)

Serpelloni, E.; Anderlini, L.; Cavaliere, A.; Danesi, S.; Pondrelli, S.; Salimbeni, S.; Danecek, P.; Massa, M.; Lovati, S.

2014-12-01

The southern Alps fold-and-thrust belt (FTB) in northern Italy is a tectonically active area accommodating large part of the ~N-S Adria-Eurasia plate convergence, that in the southeastern Alps ranges from 1.5 to 2.5 mm/yr, as constrained by a geodetically defined rotation pole. Because of the high seismic hazard of northeastern Italy, the area is well monitored at a regional scale by seismic and GPS networks. However, more localized seismotectonic and kinematic features, at the scale of the fault segments, are not yet resolved, limiting our knowledge about the seismic potential of the different fault segments belonging to the southeastern Alps FTB. Here we present the results obtained from the analysis of data collected during local seismic and geodetic experiments conducted installing denser geophysical networks across the Montello-Bassano-Belluno system, a segment of the FTB that is presently characterized by a lower sismicity rate with respect to the surrounding domains. The Montello anticline, which is the southernmost tectonic features of the southeastern Alps FTB (located ~15 km south of the mountain front), is a nice example of growing anticline associated with a blind thrust fault. However, how the Adria-Alps convergence is partitioned across the FTB and the seismic potential of the Montello thrust (the area has been struck by a Mw~6.5 in 1695 but the causative fault is still largely debated) remained still unresolved. The new, denser, GPS data show that this area is undergoing among the highest geodetic deformation rates of the entire south Alpine chain, with a steep velocity gradient across the Montello anticline. The earthquakes recorded during the experiment, precisely relocated with double difference methods, and the new earthquake focal mechanisms well correlate with available information about sub-surface geological structures and highlight the seismotectonic activity of the Montello thrust fault. We model the GPS velocities using elastic

Hanford Seismic Annual Report and Fourth Quarter Report for Fiscal Year 1999

Energy Technology Data Exchange (ETDEWEB)

AC Rohay; DC Hartshorn; SP Reidel

1999-12-07

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. Hanford Seismic Monitoring also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network. (EWRN) consist of 40 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. A major reconfiguration of the HSN was initiated at the end of this quarter and the results will be reported in the first quarter report for next fiscal year (FY2000). For the HSN, there were 390 triggers during the fourth quarter of fiscal year(FY) 1999 on the primary recording system. With the implementation of dual backup systems during the second quarter of the fiscal year and an overall increase observed in sensitivity, a total of 1632 triggers were examined, identified, and processed during this fiscal year. During the fourth quarter, 24 seismic events were located by the HSN within the reporting region of 46 degrees to 47 degrees north latitude and 119 degrees to 120 degrees west longitude 9 were earthquakes in the Columbia River Basalt Group, 2 were earthquakes in the pre-basalt sediments, 10 were earthquakes in the crystalline basement; and 2 were quarry blasts. One earthquake appears to be related to a major geologic structure, 14 earthquakes occurred in known swarm areas, and 7 earthquakes were random occurrences.

Development of a Real-Time GPS/Seismic Displacement Meter: Seismic Component and Communications

Science.gov (United States)

Vernon, F.; Bock, Y.

2002-12-01

In two abstracts, we report on an ongoing effort to develop an Integrated Real-Time GPS/Seismic System for Orange and Western Riverside Counties, California, spanning three major strike-slip faults in southern California (San Andreas, San Jacinto, and Elsinore) and significant populations and civilian infrastructure. The system relying on existing GPS and seismic networks will collect and analyze GPS and seismic data for the purpose of estimating and disseminating real-time positions and total ground displacements (dynamic, as well as static) covering all phases of the seismic cycle, from fractions of seconds to years. Besides its intrinsic scientific use as a real-time displacement meter (transducer), the GPS/Seismic System will be a powerful tool for local and state decision makers for risk mitigation, disaster management, and structural monitoring (dams, bridges, and buildings). Furthermore, the GPS/Seismic System will become an integral part of California's spatial referencing and positioning infrastructure, which is complicated by tectonic motion, seismic displacements, and land subsidence. This development is taking place under the umbrella of the California Spatial Reference Center, in partnership with local (The Counties, Riverside County Flood and Water Conservation District, Southern California Metropolitan Water District), state (Caltrans), and Federal agencies (NGS, NASA, USGS), the geophysics community (SCEC2/SCIGN), and the private sector (RBF Consulting). The project is leveraging considerable funding, resources, and research and development from SCIGN, CSRC and two NSF-funded IT projects at UCSD and SDSU: RoadNet (Real-Time Observatories, Applications and Data Management Network) and the High Performance Wireless Research and Education Network (HPWREN). These two projects are funded to develop both the wireless networks and the integrated, seamless, and transparent information management system that will deliver seismic, geodetic, oceanographic

Three-dimensional crustal model of the Moravo-Silesian region obtained by seismic tomography

Czech Academy of Sciences Publication Activity Database

Růžek, Bohuslav; Holub, Karel; Rušajová, Jana

2011-01-01

Roč. 55, č. 1 (2011), s. 87-107 ISSN 0039-3169 R&D Projects: GA AV ČR IAA200120701; GA MŽP SB/630/3/02; GA ČR GA205/03/0999 Institutional research plan: CEZ:AV0Z30120515; CEZ:AV0Z30860518 Keywords : seismic tomography * 3D seismic velocity model * Moravo-Silesian region Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.700, year: 2011

Seismic Ecology

Science.gov (United States)

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

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

Local seismic monitoring east and north of Toronto - Volume 1

International Nuclear Information System (INIS)

Mohajer, A.A.; Doughty, M.

1996-08-01

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

Hydrocarbon Induced Seismicity in Northern Netherlands

Science.gov (United States)

Dost, B.; Spetzler, J.; Kraaijpoel, D.; Caccavale, M.

2015-12-01

The northern Netherlands has been regarded aseismic until the first earthquakes started in 1986, after more than 25 years of gas production from the one of the largest on-shore gas-fields in the World, the Groningen field, and accompanying smaller gas fields. Due to the shallow sources, at approximately 3 km depth, even small magnitude events cause considerable damage to buildings in the region. Since the largest recorded event in the Groningen field in 2012 with ML= 3,6, more than 30.000 damage claims were received by the mining company. Since 1995 a seismic monitoring network is operational in the region, consisting of 8 200m deep boreholes with 4 levels of 3C 4,5 Hz geophones. The network was designed for a location threshold of ML=1,5 over a 40x 80 km region. Average station separation was 20 km. At the end of 2014, 245 events have been recorded with ML ≥ 1,5, out of a total of 1100. Since 2003 a new mining law is in place in the Netherlands, which requires for each gas field in production a seismic risk analysis. Initially, due to the small number of events for specific fields, a general hazard (PSHA) was calculated for all gas-fields and a maximum magnitude was estimated at ML = 3,9. Since 2003 an increase in the activity rate is observed for the Groningen field, leading to the development of new models and a re-assessment of parameters like the maximum magnitude. More recently these models are extended to seismic risk, where also the fragility of the regional buildings is taken into account. Understanding the earthquake process is essential in taking mitigation measures. Continued research is focused on reducing the uncertainties in the hazard and risk models and is accompanied by an upgrade of the monitoring network. In 2014 a new dense network was designed to monitor the Groningen gas field in this region (30*40 km) with an average separation of 4 km. This allows an improved location threshold (M>0,5) and location accuracy (50-100m). A detailed P- and S

The Seismic Broad Band Western Mediterranean (wm) Network and the Obs Fomar Pool: Current state and Obs activities.

Science.gov (United States)

Pazos, Antonio; Davila, Jose Martin; Buforn, Elisa; Bezzeghoud, Mourad; Harnafi, Mimoun; Mattesini, Mauricio; Caldeira, Bento; Hanka, Winfried; El Moudnib, Lahcen; Strollo, Angelo; Roca, Antoni; Lopez de Mesa, Mireya; Dahm, Torsten; Cabieces, Roberto

2016-04-01

The Western Mediterranean (WM) seismic network started in 1996 as an initiative of the Royal Spanish Navy Observatory (ROA) and the Universidad Complutense de Madrid (UCM), with the collaboration of the GeoForschungsZentrum (GFZ) of Potsdam. A first broad band seismic station (SFUC) was installed close to Cádiz (South Spain). Since then, additional stations have been installed in the Ibero-Moghrebian region. In 2005, the "WM" code was assigned by the FDSN and new partners were jointed: Evora University (UEVO, Portugal), the Scientifique Institute of Rabat (ISRABAT, Morocco), and GFZ. Now days, the WM network is composed by 15 BB stations, all of them with Streckaisen STS-2 or STS-2.5 sensors, Quanterra or Earthdata digitizers and SeiscomP. Most them have co-installed a permanent geodetic GPS stations, and some them also have an accelerometer. There are 10 stations deployed in Spanish territory (5 in the Iberian peninsula, 1 in Balearic islands and 4 in North Africa Spanish places) with VSAT or Internet communications, 2 in Portugal (one of them without real time), and 3 in Morocco (2 VSAT and 1 ADSL). Additionally, 2 more stations (one in South Spain and one in Morocco) will be installed along this year. Additionally ROA has deployed a permanent real time VBB (CMG-3T: 360s) station at the Alboran Island. Due to the fact that part of the seismic activity is located at marine areas, and also because of the poor geographic azimuthal coverage at some zones provided by the land stations (specially in the SW of the San Vicente Cape area), ROA and UCM have acquired six broad band "LOBSTERN" OBS, manufactured by KUM (Kiel, Germany), conforming the OBS FOMAR pool. Three of them with CMG-40T sensor and the other with Trillium 120. These OBS were deployed along the Gibraltar strait since January to November 2014 to study the microseismicity in the Gibraltar strait area. In September 2015 FOMAR network has been deployed in SW of the San Vicente Cape for 8 months as a part of

Probabilistic seismic hazard at the archaeological site of Gol ...

Indian Academy of Sciences (India)

Shivakumar G Patil

2018-03-02

Mar 2, 2018 ... Probabilistic seismic hazard analysis (PSHA) is carried out for the ... controlling scenario earthquake for the study region as low to .... west of the city of Hyderabad in south India (see ..... declustering algorithm developed by Gardner and. Knopoff .... sparse digital strong-motion networks. ..... The trivial case of.

Two case studies of post-seismic regime in the Vrancea region

International Nuclear Information System (INIS)

Ciucu, I.; Fulga, C.

2008-01-01

The main geophysical conceptions regarding the tectonic seismicity of the Vrancea region are presented, with emphasis on great historical earthquakes as recorded by the Romanian Earthquake Catalogue. Their geographical and in-depth distribution is also presented, as well as their main characteristics. The post-seismic regime of two main events in Vrancea (August 1986 and May 1990) is analyzed, and Omori exponents are derived for the aftershocks distribution. One exponent agrees qualitatively with the usual range of exponents (0.8 with respect to 1), while the other exponent seems to be outside this range (0.3), possibly due to an imperfect definition of the genuine aftershocks. (authors)

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

Science.gov (United States)

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

2013-12-01

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

Regional P-wave Tomography in the Caribbean Region for Plate Reconstruction

Science.gov (United States)

Li, X.; Bedle, H.; Suppe, J.

2017-12-01

The complex plate-tectonic interactions around the Caribbean Sea have been studied and interpreted by many researchers, but questions still remain regarding the formation and subduction history of the region. Here we report current progress towards creating a new regional tomographic model, with better lateral and spatial coverage and higher resolution than has been presented previously. This new model will provide improved constraints on the plate-tectonic evolution around the Caribbean Plate. Our three-dimensional velocity model is created using taut spline parameterization. The inversion is computed by the code of VanDecar (1991), which is based on the ray theory method. The seismic data used in this inversion are absolute P wave arrival times from over 700 global earthquakes that were recorded by over 400 near Caribbean stations. There are over 25000 arrival times that were picked and quality checked within frequency band of 0.01 - 0.6 Hz by using a MATLAB GUI-based software named Crazyseismic. The picked seismic delay time data are analyzed and compared with other studies ahead of doing the inversion model, in order to examine the quality of our dataset. From our initial observations of the delay time data, the more equalized the ray azimuth coverage, the smaller the deviation of the observed travel times from the theoretical travel time. Networks around the NE and SE side of the Caribbean Sea generally have better ray coverage, and smaller delay times. Specifically, seismic rays reaching SE Caribbean networks, such as XT network, generally pass through slabs under South American, Central American, Lesser Antilles, Southwest Caribbean, and the North Caribbean transform boundary, which leads to slightly positive average delay times. In contrast, the Puerto Rico network records seismic rays passing through regions that may lack slabs in the upper mantle and show slightly negative or near zero average delay times. These results agree with previous tomographic

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

Science.gov (United States)

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

2011-12-01

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

Seismic Hazard Analysis on a Complex, Interconnected Fault Network

Science.gov (United States)

Page, M. T.; Field, E. H.; Milner, K. R.

2017-12-01

In California, seismic hazard models have evolved from simple, segmented prescriptive models to much more complex representations of multi-fault and multi-segment earthquakes on an interconnected fault network. During the development of the 3rd Uniform California Earthquake Rupture Forecast (UCERF3), the prevalence of multi-fault ruptures in the modeling was controversial. Yet recent earthquakes, for example, the Kaikora earthquake - as well as new research on the potential of multi-fault ruptures (e.g., Nissen et al., 2016; Sahakian et al. 2017) - have validated this approach. For large crustal earthquakes, multi-fault ruptures may be the norm rather than the exception. As datasets improve and we can view the rupture process at a finer scale, the interconnected, fractal nature of faults is revealed even by individual earthquakes. What is the proper way to model earthquakes on a fractal fault network? We show multiple lines of evidence that connectivity even in modern models such as UCERF3 may be underestimated, although clustering in UCERF3 mitigates some modeling simplifications. We need a methodology that can be applied equally well where the fault network is well-mapped and where it is not - an extendable methodology that allows us to "fill in" gaps in the fault network and in our knowledge.

The forearc crustal evolution of Izu-Bonin (Ogasawara) region obtained by seismic reflection and refraction surveys

Science.gov (United States)

Yamashita, M.; Kodaira, S.; Takahashi, N.; Tatsumi, Y.; Kaneda, Y.

2009-12-01

The Izu-Bonin (Ogasawara)-Mariana (IBM) arc is known to the typical oceanic island arc, and it is the most suitable area to understand the growth process of island arc. By previous seismic survey and deep sea drilling, convex basements are distributed along North-South direction in present forearc region. The convex basements are reported to be formed during Oligocene and Eocene (Taylor, 1992). In IBM forearc region, the middle crust with 6 km/s is recognized by seismic survey using OBSs. In IBM region, four IODP drilling sites are proposed in order to understand comprehensive growth process of arc and continental crust evolution. Two of them are located in forearc region. Japan Agency for Marine-Earth Science and Technology (JAMSTEC) carried out multi-channel seismic reflection survey using 7,800/12,000 cu.in. air gun and 5-6 km streamer with 444/204 ch hydrophones in the IBM region since 2004. We investigate the crustal structure beneath the Izu-Bonin forearc region for contribution of IBM drilling site along five long survey lines, which are across from present volcanic front to forearc basin. Seismic refraction survey is also conducted across forearc region using 84 OBSs every 1 km interval. Shallow crustal structure can be classified four units including basement which compared between previous drilling results and obtained seismic profiles. In IBM forearc region, thick sedimentary basin distribute from east side of volcanic front. Two convex basement peaks are indicated in across profile of forearc region. These peaks are estimated the top of paleoarc (Oligocene and Eocene) by previous ODP drilling. The half graben structure with major displacement is identified from west side of present volcanic front to the top of Oligocene arc. On the other hand, there is no displacement of sediments between the Oligocene arc and Eocene arc. This result shows the same origin of basement between the present volcanic front and Oligocene arc. There is long time difference of

Implications of Seismically Active Fault Structures in Ankay and Alaotra Regions of Northern and Central Madagascar

Science.gov (United States)

Malloy, S.; Stamps, D. S.

2017-12-01

The purpose of the study is to gain a better understanding of the seismically active fault structures in central and northern Madagascar. We study the Ankay and Lake Alaotra regions of Madagascar, which are segmented by multiple faults that strike N-S. In general, normal seismic events occur on faults bounding the Alaotra-Ankay rift basin where Quaternary alluvium is present. Due to this pattern and moderate amounts of low magnitude seismic activity along these faults, it is hypothesized the region currently undergoes E-W extension. In this work we test how variations in fault strength and net slip changes influence expected crustal movement in the region. Using the Coulomb stress failure point as a test of strength we are able to model the Alaotra-Ankay region using MATLAB Coulomb 3.3.01. This program allows us to define realistic Poisson's ratio and Young's modulus of mapped rock compositions in the region, i.e. paragneiss and orthogneiss, create 3D fault geometries, and calculate static stress changes with coinciding surface displacements. We impose slip along multiple faults and calculate seismic moment that we balance by the 3 observed earthquake magnitudes available in the USGS CMT database. Our calculations of surface displacements indicate 1-3 millimeters could be observed across the Alaotra-Ankay rift. These values are within the observable range of precision GNSS observations, therefore our results will guide future research into the area and direct potential GNSS station installation.

Seismic verification of underground explosions

International Nuclear Information System (INIS)

Glenn, L.A.

1986-01-01

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

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

Science.gov (United States)

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

2009-04-01

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

First Quarter Hanford Seismic Report for Fiscal Year 2001

Energy Technology Data Exchange (ETDEWEB)

Hartshorn, Donald C.; Reidel, Stephen P.; Rohay, Alan C.; Valenta, Michelle M.

2001-02-27

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. Hanford Seismic Monitoring also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (EWRN) consist of 41 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. For the HSN, there were 477 triggers during the first quarter of fiscal year (FY) 2001 on the data acquisition system. Of these triggers, 176 were earthquakes. Forty-five earthquakes were located in the HSN area; 1 earthquake occurred in the Columbia River Basalt Group, 43 were earthquakes in the pre-basalt sediments, and 1 was earthquakes in the crystalline basement. Geographically, 44 earthquakes occurred in swarm areas, 1 earthquake was on a major structure, and no earthquakes were classified as random occurrences. The Horse Heaven Hills earthquake swarm area recorded all but one event during the first quarter of FY 2001. The peak of the activity occurred over December 12th, 13th, and 14th when 35 events occurred. No earthquakes triggered the Hanford Strong Motion Accelerometers during the first quarter of FY 2001.

Geophysical Observatory in Kamchatka region for monitoring of phenomena connected with seismic activity

Science.gov (United States)

Uyeda, S.; Nagao, T.; Hattori, K.; Hayakawa, M.; Miyaki, K.; Molchanov, O.; Gladychev, V.; Baransky, L.; Chtchekotov, A.; Fedorov, E.; Pokhotelov, O.; Andreevsky, S.; Rozhnoi, A.; Khabazin, Y.; Gorbatikov, A.; Gordeev, E.; Chebrov, V.; Sinitzin, V.; Lutikov, A.; Yunga, S.; Kosarev, G.; Surkov, V.; Belyaev, G.

Regular monitoring of some geophysical parameters in association with seismicity has been carried out since last year at the Japan-Russian Complex Geophysical Observatory in the Kamchatka region. This observatory was organized in connection with the ISTC project in Russia and was motivated by the results of the FRONTIER/RIKEN and FRONTIER/NASDA research projects in Japan. The main purpose of the observations is to investigate the electromagnetic and acoustic phenomena induced by the lithosphere processes (especially by seismic activity). The seismicity of the Kamchatka area is analyzed and a description of the observatory equipment is presented. At present, the activity of the observatory includes the seismic (frequency range ∆F = 0.5 - 40 Hz) and meteorological recordings, together with seismo-acoustic (∆F = 30 - 1000 Hz) and electromagnetic observations: three-component magnetic ULF variations ( ∆F = 0.003 - 30 Hz), three-component electric potential variations ( ∆F < 1.0 Hz), and VLF transmitter's signal perturbations ( ∆F ~ 10 - 40 kHz).

Broadband seismic deployments in East Antarctica: IPY contribution to monitoring the Earth’s interiors

Directory of Open Access Journals (Sweden)

Masaki Kanao

2014-06-01

Full Text Available “Deployment of broadband seismic stations on the Antarctica continent” is an ambitious project to improve the spatial resolution of seismic data across the Antarctic Plate and surrounding regions. Several international collaborative programs for the purpose of geomonitoring were conducted in Antarctica during the International Polar Year (IPY 2007-2008. The Antarctica’s GAmburtsev Province (AGAP; IPY #147, the GAmburtsev Mountain SEISmic experiment (GAMSEIS, a part of AGAP, and the Polar Earth Observing Network (POLENET; IPY #185 were major contributions in establishing a geophysical network in Antarctica. The AGAP/GAMSEIS project was an internationally coordinated deployment of more than 30 broadband seismographs over the crest of the Gambursev Mountains (Dome-A, Dome-C and Dome-F area. The investigations provide detailed information on crustal thickness and mantle structure; provide key constraints on the origin of the Gamburtsev Mountains; and more broadly on the structure and evolution of the East Antarctic craton and subglacial environment. From GAMSEIS and POLENET data obtained, local and regional seismic signals associated with ice movements, oceanic loading, and local meteorological variations were recorded together with a significant number of teleseismic events. In this chapter, in addition to the Earth’s interiors, we will demonstrate some of the remarkable seismic signals detected during IPY that illustrate the capabilities of broadband seismometers to study the sub-glacial environment, particularly at the margins of Antarctica. Additionally, the AGAP and POLENET stations have an important role in the Federation of Digital Seismographic Network (FDSN in southern high latitude.

Along-Strike Differences of the Main Himalayan Thrust and Deformation within the Indian Crust: Insights from Seismicity and Seismic Velocities in Bhutan and its Foreland

Science.gov (United States)

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

2015-12-01

The seismicity of Bhutan is characterized by the apparent lack of great earthquakes and a significantly lower activity compared to most other parts of the Himalayan arc. To better understand the underlying mechanisms of this anomalously low activity and to relate it with possible along-strike differences in the structure of the orogenic belt, a temporary network with up to 38 broadband seismometers was installed in Bhutan between January 2013 and November 2014. In this work we present a catalog of local and regional earthquakes detected and located with the GANSSER network complemented by regional stations in India, Bangladesh, and China. State-of-the-art data analysis and earthquake location procedures were applied to derive a high-precision earthquake catalog of Bhutan and surrounding regions. Focal mechanisms from regional moment tensor inversions and first-motion polarities complement the earthquake catalog. In the vicinity of the Shumar-Kuru Chu Spur in East Bhutan, seismicity forms a moderately dipping structure at about 12 km depth, which we associate with the Main Himalayan Thrust (MHT). North of 27.6°N the dip of the structure steepens, which can be interpreted as a ramp along the MHT. In West Bhutan seismicity occurs at depths of 20 to 40 km and receiver function images indicate that seismicity occurs in the underthrusting Indian crust rather than on the MHT. The highest seismic activity is clustered along the Goalpara Lineament, a dextral NE-SW striking shear zone in southwest Bhutan, which appears to connect to the western edge of the Shillong Plateau in the foreland. Focal depths indicate that this shear zone is located at depths of 20-30 km and therefore in the underthrusting Indian crust. Preliminary results of a 3D local earthquake tomography show substantial differences in the uppermost crust between east and west Bhutan. Consistent with our receiver function images, the results also indicate a thinning of the crustal root towards eastern Bhutan.

Seismic Regionalization of Michoacan, Mexico and Recurrence Periods for Earthquakes

Science.gov (United States)

Magaña García, N.; Figueroa-Soto, Á.; Garduño-Monroy, V. H.; Zúñiga, R.

2017-12-01

Michoacán is one of the states with the highest occurrence of earthquakes in Mexico and it is a limit of convergence triggered by the subduction of Cocos plate over the North American plate, located in the zone of the Pacific Ocean of our country, in addition to the existence of active faults inside of the state like the Morelia-Acambay Fault System (MAFS).It is important to make a combination of seismic, paleosismological and geological studies to have good planning and development of urban complexes to mitigate disasters if destructive earthquakes appear. With statistical seismology it is possible to characterize the degree of seismic activity as well as to estimate the recurrence periods for earthquakes. For this work, seismicity catalog of Michoacán was compiled and homogenized in time and magnitude. This information was obtained from world and national agencies (SSN, CMT, etc), some data published by Mendoza and Martínez-López (2016) and starting from the seismic catalog homogenized by F. R. Zúñiga (Personal communication). From the analysis of the different focal mechanisms reported in the literature and geological studies, the seismic regionalization of the state of Michoacán complemented the one presented by Vázquez-Rosas (2012) and the recurrence periods for earthquakes within the four different seismotectonic regions. In addition, stable periods were determined for the b value of the Gutenberg-Richter (1944) using the Maximum Curvature and EMR (Entire Magnitude Range Method, 2005) techniques, which allowed us to determine recurrence periods: years for earthquakes upper to 7.5 for the subduction zone (A zone) with EMR technique and years with MAXC technique for the same years for earthquakes upper to 5 for B1 zone with EMR technique and years with MAXC technique; years for earthquakes upper to 7.0 for B2 zone with EMR technique and years with MAXC technique; and the last one, the Morelia-Acambay Fault Sistem zone (C zone) years for earthquakes

The ordered network structure and prediction summary for M ≥ 7 earthquakes in Xinjiang region of China

International Nuclear Information System (INIS)

Men, Ke-Pei; Zhao, Kai

2014-01-01

M ≥ 7 earthquakes have showed an obvious commensurability and orderliness in Xinjiang of China and its adjacent region since 1800. The main orderly values are 30 a x k (k = 1, 2, 3), 11 ∝ 12 a, 41 ∝ 43 a, 18 ∝ 19 a, and 5 ∝ 6 a. In the guidance of the information forecasting theory of Wen-Bo Weng, based on previous research results, combining ordered network structure analysis with complex network technology, we focus on the prediction summary of M ≥ 7 earthquakes by using the ordered network structure, and add new information to further optimize network, hence construct the 2D- and 3D-ordered network structure of M ≥ 7 earthquakes. In this paper, the network structure revealed fully the regularity of seismic activity of M ≥ 7 earthquakes in the study region during the past 210 years. Based on this, the Karakorum M7.1 earthquake in 1996, the M7.9 earthquake on the frontier of Russia, Mongol, and China in 2003, and two Yutian M7.3 earthquakes in 2008 and 2014 were predicted successfully. At the same time, a new prediction opinion is presented that the future two M ≥ 7 earthquakes will probably occur around 2019-2020 and 2025-2026 in this region. The results show that large earthquake occurred in defined region can be predicted. The method of ordered network structure analysis produces satisfactory results for the mid-and-long term prediction of M ≥ 7 earthquakes.

Modern Adaptive Analytics Approach to Lowering Seismic Network Detection Thresholds

Science.gov (United States)

Johnson, C. E.

2017-12-01

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

Seismic instrumentation plan for the Hawaiian Volcano Observatory

Science.gov (United States)

Thelen, Weston A.

2014-01-01

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

Seismic vulnerability assessment of chemical plants through probabilistic neural networks

International Nuclear Information System (INIS)

Aoki, T.; Ceravolo, R.; De Stefano, A.; Genovese, C.; Sabia, D.

2002-01-01

A chemical industrial plant represents a sensitive presence in a region and, in case of severe damage due to earthquake actions, its impact on social life and environment can be devastating. From the structural point of view, chemical plants count a number of recurrent elements, which are classifiable in a discrete set of typological families (towers, chimneys, cylindrical or spherical or prismatic tanks, pipes etc.). The final aim of this work is to outline a general procedure to be followed in order to assign a seismic vulnerability estimate to each element of the various typological families. In this paper, F.E. simulations allowed to create a training set, which has been used to train a probabilistic neural system. A sample application has concerned the seismic vulnerability of simple spherical tanks

A new seismic station in Romania the Bucovina seismic array

International Nuclear Information System (INIS)

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

2002-01-01

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

Technique and the scheme of engineering-seismometric supervision over seismic events on large dams

Energy Technology Data Exchange (ETDEWEB)

Karapetyan, S.; Babayan, T.; Mkrtchyan, G. [National Academy of Sciences of the Republic of Armenia (Armenia). Inst. of Geophysics and Engineering Seismology

2004-07-01

A network of engineering-seismometric monitoring stations have been installed at the Tavshout dam in a seismically active region of Armenia. The 37 meter high embankment dam consists of gravel-pebbles with a core of sandy clay. Recent earthquakes have presented a direct hazard for the dam and its water reservoir. In order to determine the degree of seismic hazard and prevention, it is necessary to study the interaction between the ground and the foundation of the dam. The seismometers were fixed at three points both on the foundation and the ground to obtain information on the whole route of seismic waves and to define the geology based amplification factors using empirical equations. The system of engineering-seismometric observations included a network of seismometric instruments, communications and a recording complex. 4 refs., 14 figs.

Mechanism of post-seismic floods after the Wenchuan earthquake in ...

Indian Academy of Sciences (India)

Ding Hairong

2017-10-06

Oct 6, 2017 ... development of devastating post-seismic floods. Thirdly, the ... The segment from. Dujiangyan city to the upstream source of the river is known .... trends downward in the region. ..... quake: A case study in the upper reaches of the Min River,. Sichuan .... the digital strong earthquake network in Sichuan and.

Reducing Seismic Hazard and Building Capacity Through International Cooperation

Science.gov (United States)

Vergino, E. S.; Arakelyan, A.; Babayan, H.; Durgaryan, R.; Elashvili, M.; Godoladze, T.; Javakhishvili, Z.; Kalogeras, I.; Karakhanyan, A.; Martin, R. J.; Yetirmishli, G.

2012-12-01

During the last 50 years, the Caucasus, Central Asia and the Caspian Sea regions have experienced several devastating earthquakes. While each country in the region has worked with its neighbors on small, ad-hoc projects to improve preparedness, deeply ingrained political and ethnic rivalries, and severely stressed economies have severely hindered sustained regional cooperation. Future damaging earthquakes are inevitable and without proper planning the negative impact on public safety, security, economics and stability in these regions will be devastating. We have, through twelve years of international scientific cooperation, focused on the development of an expanded skill base and infrastructure, through the installation of new, modern, digital seismic monitoring networks, building of historic databases, sharing seismic, geologic and geophysical data, conducting joint scientific investigations utilizing the new digital data and applying modern techniques, as well as the development of regional hazard models that the scientists of the region share with their governments and use to advise them on the best ways to mitigate the impact of a damaging earthquake. We have established specialized regional scientific task-force teams who can carry out seismological, geological and engineering studies in the epicentral zone, including the collection of new scientific data, for better understanding of seismic and geodynamic processes as well to provide emergency support in crisis and post-crisis situations in the Southern Caucasus countries. "Secrecy" in crisis and post-crisis situations in the former Soviet Union countries, as well as political instabilities, led to an absence of seismic risk reduction and prevention measures as well as little to no training of scientific-technical personnel who could take action in emergency situations. There were few opportunities for the development of a next generation of scientific experts, thus we have placed emphasis on the inclusion

Serviceability Assessment for Cascading Failures in Water Distribution Network under Seismic Scenario

Directory of Open Access Journals (Sweden)

Qing Shuang

2016-01-01

Full Text Available The stability of water service is a hot point in industrial production, public safety, and academic research. The paper establishes a service evaluation model for the water distribution network (WDN. The serviceability is measured in three aspects: (1 the functionality of structural components under disaster environment; (2 the recognition of cascading failure process; and (3 the calculation of system reliability. The node and edge failures in WDN are interrelated under seismic excitations. The cascading failure process is provided with the balance of water supply and demand. The matrix-based system reliability (MSR method is used to represent the system events and calculate the nonfailure probability. An example is used to illustrate the proposed method. The cascading failure processes with different node failures are simulated. The serviceability is analyzed. The critical node can be identified. The result shows that the aged network has a greater influence on the system service under seismic scenario. The maintenance could improve the antidisaster ability of WDN. Priority should be given to controlling the time between the initial failure and the first secondary failure, for taking postdisaster emergency measures within this time period can largely cut down the spread of cascade effect in the whole WDN.

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

Seismicity, seismic input and site effects in the Sahel-Algiers region (north Algeria)

International Nuclear Information System (INIS)

Harbi, A.; Maouche, S.; Oussadou, F.; Vaccari, F.; Aoudia, A.; Panza, G.F.; Benouar, D.

2005-07-01

Algiers city is located in a seismogenic zone. To reduce the impact of seismic risk in this capital city, a realistic modelling of the seismic ground motion using the hybrid method that combines the finite-differences method and the modal summation, is conducted. For this purpose, a complete database in terms of geological, geophysical and earthquake data is constructed. A critical re-appraisal of the seismicity of the zone (2.25 deg. E-3.50 deg. E, 36.50 deg. N-37.00 deg. N) is performed and an earthquake list, for the period 1359-2002, is compiled. The analysis of existing and newly retrieved macroseismic information allowed the definition of earthquake parameters of macroseismic events for which a degree of reliability is assigned. Geological cross-sections have been built up to model the seismic ground motion in the city, caused by the 1989 Mont-Chenoua and the 1924 Douera earthquakes; a set of synthetic seismograms and response spectral ratio is produced for Algiers. The numerical results show that the soft sediments in Algiers centre are responsible of the noticed amplification of the seismic ground motion. (author)

Geophysical Observatory in Kamchatka region for monitoring of phenomena connected with seismic activity

Directory of Open Access Journals (Sweden)

S. Uyeda

2001-01-01

Full Text Available Regular monitoring of some geophysical parameters in association with seismicity has been carried out since last year at the Japan-Russian Complex Geophysical Observatory in the Kamchatka region. This observatory was organized in connection with the ISTC project in Russia and was motivated by the results of the FRONTIER/RIKEN and FRONTIER/NASDA research projects in Japan. The main purpose of the observations is to investigate the electromagnetic and acoustic phenomena induced by the lithosphere processes (especially by seismic activity. The seismicity of the Kamchatka area is analyzed and a description of the observatory equipment is presented. At present, the activity of the observatory includes the seismic (frequency range ∆F = 0.5 – 40 Hz and meteorological recordings, together with seismo-acoustic (∆F = 30 – 1000 Hz and electromagnetic observations: three-component magnetic ULF variations ( ∆F = 0.003 – 30 Hz, three-component electric potential variations ( ∆F 1.0 Hz, and VLF transmitter’s signal perturbations ( ∆F ~ 10 – 40 kHz.

Seismic gaps and plate tectonics: seismic potential for major boundaries

Energy Technology Data Exchange (ETDEWEB)

McCann, W R; Nishenko, S P; Sykes, L R; Krause, J

1979-01-01

The theory of plate tectonics provides a basic framework for evaluating the potential for future great earthquakes to occur along major plate boundaries. Along most of the transform and convergent plate boundaries considered in this paper, the majority of seismic slip occurs during large earthquakes, i.e., those of magnitude 7 or greater. The concepts that rupture zones, as delineated by aftershocks, tend to abut rather than overlap, and large events occur in regions with histories of both long-and short-term seismic quiescence are used in this paper to delineate major seismic gaps. The term seismic gap is taken to refer to any region along an active plate boundary that has not experienced a large thrust or strike-slip earthquake for more than 30 years. A region of high seismic potential is a seismic gap that, for historic or tectonic reasons, is considered likely to produce a large shock during the next few decades. The seismic gap technique provides estimates of the location, size of future events and origin time to within a few tens of years at best. The accompanying map summarizes six categories of seismic potential for major plate boundaries in and around the margins of the Pacific Ocean and the Caribbean, South Sandwich and Sunda (Indonesia) regions for the next few decades. These six categories are meant to be interpreted as forecasts of the location and size of future large shocks and should not be considered to be predictions in which a precise estimate of the time of occurrence is specified. The categories of potential assigned here provide a rationale for assigning priorities for instrumentation, for future studies aimed at predicting large earthquakes and for making estimates of tsunami potential.

Seismic risk assessment for road in Indonesia

Science.gov (United States)

Toyfur, Mona Foralisa; Pribadi, Krishna S.

2016-05-01

Road networks in Indonesia consist of 446,000 km of national, provincial and local roads as well as toll highways. Indonesia is one of countries that exposed to various natural hazards, such as earthquakes, floods, landslides, etc. Within the Indonesian archipelago, several global tectonic plates interact, such as the Indo-Australian, Pacific, Eurasian, resulting in a complex geological setting, characterized by the existence of seismically active faults and subduction zones and a chain of more than one hundred active volcanoes. Roads in Indonesia are vital infrastructure needed for people and goods movement, thus supporting community life and economic activities, including promoting regional economic development. Road damages and losses due to earthquakes have not been studied widely, whereas road disruption caused enormous economic damage. The aim of this research is to develop a method to analyse risk caused by seismic hazard to roads. The seismic risk level of road segment is defined using an earthquake risk index, adopting the method of Earthquake Disaster Risk Index model developed by Davidson (1997). Using this method, road segments' risk level can be defined and compared, and road risk map can be developed as a tool for prioritizing risk mitigation programs for road networks in Indonesia.

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

Science.gov (United States)

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

2012-04-01

the seismic activity and an efficient seismo-volcanic surveillance. The data are processed and analyzed using the SEISAN database management software. In addition to the seismic network, we deployed a small-aperture seismic array south of Fumarole Bay. It is composed by 9 vertical and 1 three-component short-period stations. The 24-bit data acquisition system samples these 12 channels at 100 sps. There is also a permanent seismic station operating since 2008 and located near GdC, that is very useful for the preliminary evaluation of the seismicity at the start of the survey. This station is composed by a 16-s electrolytic seismometer (Eentec SP400) and a 24-bit datalogger (Eentec DR4000) sampling at 100 sps. During the 2010-2011 survey we identified 33 regional earthquakes, 80 volcano-tectonic (VT) earthquakes, and 929 long-period (LP) events. The volcanic alert system has remained green (the lowest level) at all times. The seismic activity has been similar to previous surveys and remained within limits that are normal for the island.

Second and Third Quarters Hanford Seismic Report for Fiscal Year 1999

Energy Technology Data Exchange (ETDEWEB)

DC Hartshorn; SP Reidel; AC Rohay

1999-11-09

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. Hanford Seismic Monitoring also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (EWRN) consist of 42 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. For the HSN, there were 270 triggers during the second quarter of fiscal year (FY) 1999 and 229 triggers during the third quarter on the primary recording system. During the second quarter, 22 seismic events were located; 11 were earthquakes in the Columbia River Basalt Group, 6 were earthquakes in the crystalline basement, and 5 were quarry blasts. Two earthquakes appear to be related to major geologic structures, eight earthquakes occurred in known swarm areas, and seven earthquakes were random occurrences. During the third quarter, 23 seismic events were located; 11 were earthquakes in the Columbia River Basalt Group, 4 were earthquakes in the pre-basalt sediments, 4 were earthquakes in the crystalline basement, and 4 were quarry blasts. Five earthquakes occurred in known swarm areas, six earthquakes formed a new swarm near the Horse Heavens Hills and Presser, Washington, and eight earthquakes were random occurrences. No earthquakes triggered the Hanford Strong Motion Accelerometers during the second or third quarters of FY 1999.

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

International Nuclear Information System (INIS)

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

1998-01-01

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

The 2017 Maple Creek Seismic Swarm in Yellowstone National Park

Science.gov (United States)

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

2017-12-01

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

Seismic fault analysis of Chicoutimi region

International Nuclear Information System (INIS)

Woussen, G.; Ngandee, S.

1996-01-01

On November 25, 1988, an earthquake measuring 6.5 on the Richter Scale occurred at a depth of 29 km in Precambrian bedrock in the Saguenay Region (Quebec). Given that the seismic event was located near a major zone of normal faults, it is important to determine if the earthquake could be associated with this large structure or with faults associated with this structure. This is discussed through a compilation and interpretation of structural discontinuities on key outcrops in the vicinity of the epicenter. The report is broken in four parts. The first part gives a brief overview of the geology in order to provide a geologic context for the structural measurements. The second comprises an analysis of fractures in each of the three lithotectonic units defined in the first part. The third part discusses the data and the fourth provides a conclusion. 30 refs., 53 figs

Crustal velocity structure of central Gansu Province from regional seismic waveform inversion using firework algorithm

Science.gov (United States)

Chen, Yanyang; Wang, Yanbin; Zhang, Yuansheng

2017-04-01

The firework algorithm (FWA) is a novel swarm intelligence-based method recently proposed for the optimization of multi-parameter, nonlinear functions. Numerical waveform inversion experiments using a synthetic model show that the FWA performs well in both solution quality and efficiency. We apply the FWA in this study to crustal velocity structure inversion using regional seismic waveform data of central Gansu on the northeastern margin of the Qinghai-Tibet plateau. Seismograms recorded from the moment magnitude ( M W) 5.4 Minxian earthquake enable obtaining an average crustal velocity model for this region. We initially carried out a series of FWA robustness tests in regional waveform inversion at the same earthquake and station positions across the study region, inverting two velocity structure models, with and without a low-velocity crustal layer; the accuracy of our average inversion results and their standard deviations reveal the advantages of the FWA for the inversion of regional seismic waveforms. We applied the FWA across our study area using three component waveform data recorded by nine broadband permanent seismic stations with epicentral distances ranging between 146 and 437 km. These inversion results show that the average thickness of the crust in this region is 46.75 km, while thicknesses of the sedimentary layer, and the upper, middle, and lower crust are 3.15, 15.69, 13.08, and 14.83 km, respectively. Results also show that the P-wave velocities of these layers and the upper mantle are 4.47, 6.07, 6.12, 6.87, and 8.18 km/s, respectively.

Geophysical investigations of the Western Ohio-Indiana region

International Nuclear Information System (INIS)

Ruff, L.; LaForge, R.; Thorson, R.; Wagner, T.; Goudaen, F.

1994-01-01

Earthquake activity in the Western Ohio-Indiana region has been monitored with a seismograph network consisting of nine stations located in west-central Ohio and four stations located in Indiana. Six local and regional earthquakes have been recorded from October 1990 to September 1992 with magnitudes ranging from 0.6 to 5.0. A total of 36 local and regional earthquakes have been recorded in the past 6-year period (October 1986 to September 1992). Overall a total of 78 local and regional earthquakes have been recorded since the network went into operation in 1977. There was a peak in seismicity in 1986, including the July 12, 1986 St. Marys' event (mb=4.5), followed by an anomalously low level of seismicity for about 2 years. The most unusual feature of the seismicity in the past.year is the occurrence of three earthquakes in Indiana. The locations of the felt earthquakes are scattered across central Indiana; an area that had been aseismic. Analysis of arrival time data accumulated over the past 14 years shows that the Anna region crustal structure is ''slower'' than the average mid-continent crustal structure. This implies that the proposed Keewenawan rift in the Anna region has a different structure than that of other Keewenawan rifts in the mid-continent

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.

PG&E's Seismic Network Goes Digital With Strong Motion: Successes and Challenges

Science.gov (United States)

Stanton, M. A.; Cullen, J.; McLaren, M. K.

2008-12-01

Pacific Gas and Electric Company (PG&E) is in year 3 of a 5-year project to upgrade the Central Coast Seismic Network (CCSN) from analog to digital. Located along the south-central California coast, the CCSN began operation in 1987, with 20 analog stations; 15 vertical component and 5 dual gain 3-component S-13 sensors. The analog signals travel over FM radio telemetry links and voice channels via PG&E's microwave network to our facility in San Francisco (SF), where the A/D conversion is performed on a computer running Earthworm v7.1, which also transmits the data to the USGS in Menlo Park. At the conversion point the dynamic ranges of the vertical and dual-gain sensors are 40-50dB and 60-70dB, respectively. Dynamic range exceedance (data clipping) generally occurs for a M2.5 or greater event within about 40 km of a station. The motivations to upgrade the seismic network were the need for higher dynamic range and to retire obsolete analog transmission equipment. The upgraded digital stations consist of the existing velocity sensors, a 131A-02/3 accelerometer and a Reftek 130-01 Broadband Seismic Recorder for digital data recording and transmission to SF. Vertical only stations have one component of velocity and 3 components of acceleration. Dual gain sites have 3 components of velocity and 3 of acceleration. To date we have successfully upgraded 6 sites; 3 more will be installed by the end of 2008. Some of the advantages of going digital are 1) data is recorded at each site and in SF, 2) substantially increased dynamic range of the velocity sensors to 120dB, as observed by on scale, close-by recordings from a M3.9 San Simeon aftershock on 04/29/2008, 3) accelerometers for on scale recording of large earthquakes, and 4) ability to contribute our strong motion data to USGS ShakeMaps. A significant challenge has been consistent radio communications. To resolve this issue we are installing point-to-multipoint Motorola Canopy spread spectrum radios at the stations and

ON THE FLARE-INDUCED SEISMICITY IN THE ACTIVE REGION NOAA 10930 AND RELATED ENHANCEMENT OF GLOBAL WAVES IN THE SUN

International Nuclear Information System (INIS)

Kumar, Brajesh; Venkatakrishnan, P.; Mathur, Savita; Tiwari, Sanjiv Kumar; García, R. A.

2011-01-01

A major flare (of class X3.4) occurred on 2006 December 13 in the active region NOAA 10930. This flare event has remained interesting to solar researchers for studies related to particle acceleration during the flare process and the reconfiguration of magnetic fields as well as fine-scale features in the active region. The energy released during flares is also known to induce acoustic oscillations in the Sun. Here, we analyze the line-of-sight velocity patterns in this active region during the X3.4 flare using the Dopplergrams obtained by the Global Oscillation Network Group (GONG) instrument. We have also analyzed the disk-integrated velocity observations of the Sun obtained by the Global Oscillation at Low Frequency (GOLF) instrument on board the Solar and Heliospheric Observatory spacecraft as well as full-disk collapsed velocity signals from GONG observations during this flare to study any possible connection between the flare-related changes seen in the local and global velocity oscillations in the Sun. We apply wavelet transform to the time series of the localized velocity oscillations as well as the global velocity oscillations in the Sun spanning the flare event. The line-of-sight velocity shows significant enhancement in some localized regions of the penumbra of this active region during the flare. The affected region is seen to be away from the locations of the flare ribbons and the hard X-ray footpoints. The sudden enhancement of this velocity seems to be caused by the Lorentz force driven by the 'magnetic jerk' in the localized penumbral region. Application of wavelet analysis to these flare-induced localized seismic signals shows significant enhancement in the high-frequency domain (5 <ν < 8 mHz) and a feeble enhancement in the p-mode oscillations (2 <ν < 5 mHz) during the flare. On the other hand, the wavelet analysis of GOLF velocity data and the full-disk collapsed GONG velocity data spanning the flare event indicates significant post

Seismic and tsunami hazard in Puerto Rico and the Virgin Islands

Science.gov (United States)

Dillon, William P.; Frankel, Arthur D.; Mueller, Charles S.; Rodriguez, Rafael W.; ten Brink, Uri S.

1999-01-01

first day of the workshop, participants from universities, federal institutions, and consulting firms in Puerto Rico, the Virgin Islands, the continental U.S., Dominican Republic, and Europe reviewed the present state of knowledge including a review and discussion of present plate models, recent GPS and seismic reflection data, seismicity, paleoseismology, and tsunamis. The state of earthquake/tsunami studies in Puerto Rico was presented by several faculty members from the University of Puerto Rico at Mayaguez. A preliminary seismic hazard map was presented by the USGS and previous hazard maps and economic loss assessments were considered. During the second day, the participants divided into working groups and prepared specific recommendations for future activities in the region along the six following topics below. Highlights of these recommended activities are:Marine geology and geophysics – Acquire deep-penetration seismic reflection and refraction data, deploy temporary ocean bottom seismometer arrays to record earthquakes, collect high-resolution multibeam bathymetry and side scan sonar data of the region, and in particular, the near shore region, and conduct focussed high-resolution seismic studies around faults. Determine slip rates of specific offshore faults. Assemble a GIS database for available marine geological and geophysical data.Paleoseismology and active faults - Field reconnaissance aimed at identifying Quaternary faults and determining their paleoseismic chronology and slip rates, as well as identifying and dating paleoliquefaction features from large earthquakes. Quaternary mapping of marine terraces, fluvial terraces and basins, beach ridges, etc., to establish framework for understanding neotectonic deformation of the island. Interpretation of aerial photography to identify possible Quaternary faults.Earthquake seismology – Determine an empirical seismic attenuation function using observations from local seismic networks and recently

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

Energy Technology Data Exchange (ETDEWEB)

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

1998-02-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-10-15

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

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

The evaluation of the earthquake hazard using the exponential distribution method for different seismic source regions in and around Ağrı

Energy Technology Data Exchange (ETDEWEB)

Bayrak, Yusuf, E-mail: ybayrak@agri.edu.tr [Ağrı İbrahim Çeçen University, Ağrı/Turkey (Turkey); Türker, Tuğba, E-mail: tturker@ktu.edu.tr [Karadeniz Technical University, Department of Geophysics, Trabzon/Turkey (Turkey)

2016-04-18

The aim of this study; were determined of the earthquake hazard using the exponential distribution method for different seismic sources of the Ağrı and vicinity. A homogeneous earthquake catalog has been examined for 1900-2015 (the instrumental period) with 456 earthquake data for Ağrı and vicinity. Catalog; Bogazici University Kandilli Observatory and Earthquake Research Institute (Burke), National Earthquake Monitoring Center (NEMC), TUBITAK, TURKNET the International Seismological Center (ISC), Seismological Research Institute (IRIS) has been created using different catalogs like. Ağrı and vicinity are divided into 7 different seismic source regions with epicenter distribution of formed earthquakes in the instrumental period, focal mechanism solutions, and existing tectonic structures. In the study, the average magnitude value are calculated according to the specified magnitude ranges for 7 different seismic source region. According to the estimated calculations for 7 different seismic source regions, the biggest difference corresponding with the classes of determined magnitudes between observed and expected cumulative probabilities are determined. The recurrence period and earthquake occurrence number per year are estimated of occurring earthquakes in the Ağrı and vicinity. As a result, 7 different seismic source regions are determined occurrence probabilities of an earthquake 3.2 magnitude, Region 1 was greater than 6.7 magnitude, Region 2 was greater than than 4.7 magnitude, Region 3 was greater than 5.2 magnitude, Region 4 was greater than 6.2 magnitude, Region 5 was greater than 5.7 magnitude, Region 6 was greater than 7.2 magnitude, Region 7 was greater than 6.2 magnitude. The highest observed magnitude 7 different seismic source regions of Ağrı and vicinity are estimated 7 magnitude in Region 6. Region 6 are determined according to determining magnitudes, occurrence years of earthquakes in the future years, respectively, 7.2 magnitude was in 158

Seismicity and seismogenic structures of Central Apennines (Italy): constraints on the present-day stress field from focal mechanisms - The SLAM (Seismicity of Lazio-Abruzzo and Molise) project

Science.gov (United States)

Frepoli, Alberto; Battista Cimini, Giovanni; De Gori, Pasquale; De Luca, Gaetano; Marchetti, Alessandro; Montuori, Caterina; Pagliuca, Nicola

2016-04-01

We present new results for the microseismic activity in the Central Apennines recorded from a total of 81seismic stations. The large number of recording sites derives from the combination of temporary and permanent seismic networks operating in the study region. Between January 2009 and October 2013 we recorded 6923 earthquakes with local magnitudes ML ranging from 0.1 to 4.8. We located hypocentres by using a refined 1D crustal velocity model. The majority of the hypocenters are located beneath the axes of the Apenninic chain, while the seismic activity observed along the peri-Tyrrhenian margin is lower. The seismicity extends to a depth of 32 km; the hypocentral depth distribution exhibits a pronounced peak of seismic energy release in the depth range between 8 and 20 km. During the observation period we recorded two major seismic swarms and one seismic sequence in the Marsica-Sorano area in which we have had the largest detected magnitude (ML = 4.8). Fault plane solutions for a total of 600 earthquakes were derived from P-polarities. This new data set consists of a number of focal plane solutions that is about four times the data so far available for regional stress field study. The majority of the focal mechanisms show predominantly normal fault solutions. T-axis trends are oriented NE-SW confirming that the area is in extension. We also derived the azimuths of the principal stress axes by inverting the fault plane solutions and calculated the direction of the maximum horizontal stress, which is mainly sub-vertical oriented. The study region has been historically affected by many strong earthquakes, some of them very destructive. This work can give an important contribution to the seismic hazard assessment in an area densely populated as the city of Rome which is distant around 60 km from the main seismogenic structures of Central Apennine.

Impact of the 2001 Tohoku-oki earthquake to Tokyo Metropolitan area observed by the Metropolitan Seismic Observation network (MeSO-net)

Science.gov (United States)

Hirata, N.; Hayashi, H.; Nakagawa, S.; Sakai, S.; Honda, R.; Kasahara, K.; Obara, K.; Aketagawa, T.; Kimura, H.; Sato, H.; Okaya, D. A.

2011-12-01

The March 11, 2011 Tohoku-oki earthquake brought a great impact to the Tokyo metropolitan area in both seismological aspect and seismic risk management although Tokyo is located 340 km from the epicenter. The event generated very strong ground motion even in the metropolitan area and resulted severe requifaction in many places of Kanto district. National and local governments have started to discuss counter measurement for possible seismic risks in the area taking account for what they learned from the Tohoku-oki event which is much larger than ever experienced in Japan Risk mitigation strategy for the next greater earthquake caused by the Philippine Sea plate (PSP) subducting beneath the Tokyo metropolitan area is of major concern because it caused past mega-thrust earthquakes, such as the 1703 Genroku earthquake (M8.0) and the 1923 Kanto earthquake (M7.9). An M7 or greater (M7+) earthquake in this area at present has high potential to produce devastating loss of life and property with even greater global economic repercussions. The Central Disaster Management Council of Japan estimates that an M7+ earthquake will cause 11,000 fatalities and 112 trillion yen (about 1 trillion US$) economic loss. In order to mitigate disaster for greater Tokyo, the Special Project for Earthquake Disaster Mitigation in the Tokyo Metropolitan Area was launched in collaboration with scientists, engineers, and social-scientists in nationwide institutions. We will discuss the main results that are obtained in the respective fields which have been integrated to improve information on the strategy assessment for seismic risk mitigation in the Tokyo metropolitan area; the project has been much improved after the Tohoku event. In order to image seismic structure beneath the Metropolitan Tokyo area we have developed Metropolitan Seismic Observation network (MeSO-net; Hirata et al., 2009). We have installed 296 seismic stations every few km (Kasahara et al., 2011). We conducted seismic

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

Energy Technology Data Exchange (ETDEWEB)

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

2006-03-01

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

A GIS-based multi-criteria seismic vulnerability assessment using the integration of granular computing rule extraction and artificial neural networks

NARCIS (Netherlands)

Sheikhian, Hossein; Delavar, Mahmoud Reza; Stein, Alfred

2017-01-01

This study proposes multi‐criteria group decision‐making to address seismic physical vulnerability assessment. Granular computing rule extraction is combined with a feed forward artificial neural network to form a classifier capable of training a neural network on the basis of the rules provided by

Enhancing Outreach using Social Networks at the National Seismological Network of Costa Rica

Science.gov (United States)

Linkimer, L.; Lücke, O. H.

2014-12-01

Costa Rica has a very high seismicity rate and geological processes are part of everyday life. Traditionally, information about these processes has been provided by conventional mass media (television and radio). However, due to the new trends in information flow a new approach towards Science Education is necessary for transmitting knowledge from scientific research for the general public in Costa Rica. Since 1973, the National Seismological Network of Costa Rica (RSN: UCR-ICE) studies the seismicity and volcanic activity in the country. In this study, we describe the different channels to report earthquake information that the RSN is currently using: email, social networks, and a website, as well as the development of a smartphone application. Since the RSN started actively participating in Social Networks, an increase in awareness in the general public has been noticed particularly regarding felt earthquakes. Based on this trend, we have focused on enhancing public outreach through Social Media. We analyze the demographics and geographic distribution of the RSN Facebook Page, the growth of followers, and the significance of their feedback for reporting intensity data. We observe that certain regions of the country have more Facebook activity, although those regions are not the most populated nor have a high Internet connectivity index. We interpret this pattern as the result of a higher awareness to geological hazards in those specific areas. We noticed that the growth of RSN users on Facebook has a strong correlation with the seismic events as opposed to Twitter that displays a steady growth with no clear correlations with specific seismic events. We see the Social Networks as opportunities to engage non-science audiences and encourage the population to participate in reporting seismic observations, thus providing intensity data. With the increasing access to Internet from mobile phones in Costa Rica, we see this approach to science education as an opportunity

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

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

Science.gov (United States)

Dorman, H. J.

1981-01-01

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

Recent Seismicity in the Ceboruco Volcano, Western Mexico

Science.gov (United States)

Nunez, D.; Chávez-Méndez, M. I.; Nuñez-Cornu, F. J.; Sandoval, J. M.; Rodriguez-Ayala, N. A.; Trejo-Gomez, E.

2017-12-01

The Ceboruco volcano is the largest (2280 m.a.s.l) of several volcanoes along the Tepic-Zacoalco rift zone in Nayarit state (Mexico). During the last 1000 years, this volcano had effusive-explosive episodes with eight eruptions providing an average of one eruption each 125 years. Since the last eruption occurred in 1870, 147 years ago, a new eruption likelihood is really high and dangerous due to nearby population centers, important roads and lifelines that traverse the volcano's slopes. This hazards indicates the importance of monitoring the seismicity associated with the Ceboruco volcano whose ongoing activity is evidenced by fumaroles and earthquakes. During 2003 and 2008, this region was registered by just one Lennartz Marslite seismograph featuring a Lennartz Le3D sensor (1 Hz) [Rodríguez Uribe et al. (2013)] where they observed that seismicity rates and stresses appear to be increasing indicating higher levels of activity within the volcano. Until July 2017, a semi-permanent network with three Taurus (Nanometrics) and one Q330 Quanterra (Kinemetrics) digitizers with Lennartz 3Dlite sensors of 1 Hz natural frequency was registering in the area. In this study, we present the most recent seismicity obtained by the semi-permanent network and a temporary network of 21 Obsidians 4X and 8X (Kinemetrics) covering an area of 16 km x 16 km with one station every 2.5-3 km recording from November 2016 to July 2017.

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

Volcano-tectonic deformation in the Kivu Region, Central Africa: Results from six years of continuous GNSS observations of the Kivu Geodetic Network (KivuGNet)

Science.gov (United States)

Geirsson, Halldor; d'Oreye, Nicolas; Mashagiro, Niche; Syauswa, Muhindo; Celli, Gilles; Kadufu, Benjamin; Smets, Benoît; Kervyn, François

2017-10-01

We present an overview of the installation, operation, and initial results of the 15-station KivuGNet (Kivu Geodetic Network) in the Kivu Region, Central Africa. The network serves primarily as a research and monitoring tool for active volcanic, earthquake, and plate boundary processes in the region. Continuous operation of in-situ measurement networks in naturally and politically harsh environments is challenging, but has proven fruitful in this case. During the operation of the network since 2009, KivuGNet has captured: co-eruptive deformation from two eruptions of Nyamulagira (in 2010 and 2011-2012); inter-eruptive deformation, which we interpret as a combination of plate motion across the Western - East Africa Rift, and decreasing deep-seated magma accumulation under the Nyiragongo-Nyamulagira region; co-seismic deformation from the Mw5.8 August 7, 2015 Lwiro earthquake at the western border of Lake Kivu. We hope that this study will serve as a motivation for further implementation of in-situ geodetic networks in under-monitored and under-studied sections of the East African Rift.

Seismic spectra of events at regional distances

International Nuclear Information System (INIS)

Springer, D.L.; Denny, M.D.

1976-01-01

About 40 underground nuclear explosions detonated at the Nevada Test Site (NTS) were chosen for analysis of their spectra and any relationships they might have to source parameters such as yield, depth of burial, etc. The sample covered a large yield range (less than 20 kt to greater than 1 Mt). Broadband (0.05 to 20 Hz) data recorded by the four-station seismic network operated by Lawrence Livermore Laboratory were analyzed in a search for unusual explosion signatures in their spectra. Long time windows (total wave train) as well as shorter windows (for instance, P/sub n/) were used as input to calculate the spectra. Much variation in the spectra of the long windows is typical although some gross features are similar, such as a dominant peak in the microseismic window. The variation is such that selection of corner frequencies is impractical and yield scaling could not be determined. Spectra for one NTS earthquake showed more energy in the short periods (less than 1 sec) as well as in the long periods (greater than 8 sec) compared to those for NTS explosions

National Seismic Station

International Nuclear Information System (INIS)

Stokes, P.A.

1982-06-01

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

Travel time tomography of the crust and the mantle beneath Ecuador from data of the national seismic network.

OpenAIRE

Araujo , Sebastián

2016-01-01

Although there have been numerous studies on the geodynamics and the tectonics in Ecuador based on the seismic activity, there has not been to date a comprehensive tomography study using the entire database of the National Seismic Network (RENSIG). Only a preliminary limited study was performed by Prevot et al. to infer a simple P velocity model in central Ecuador, and several profiles in the South-Colombian-Ecuador margin were also investigated by using travel time inversion of wide-angle se...

A seismic design of nuclear reactor building structures applying seismic isolation system in a seismicity region-a feasibility case study in Japan

Energy Technology Data Exchange (ETDEWEB)

Kubo, Tetsuo [The University of Tokyo, Tokyo (Japan); Yamamoto, Tomofumi; Sato, Kunihiko [Mitsubishi Heavy Industries, Ltd., Kobe (Japan); Jimbo, Masakazu [Toshiba Corporation, Yokohama (Japan); Imaoka, Tetsuo [Hitachi-GE Nuclear Energy, Ltd., Hitachi (Japan); Umeki, Yoshito [Chubu Electric Power Co. Inc., Nagoya (Japan)

2014-10-15

A feasibility study on the seismic design of nuclear reactor buildings with application of a seismic isolation system is introduced. After the Hyogo-ken Nanbu earthquake in Japan of 1995, seismic isolation technologies have been widely employed for commercial buildings. Having become a mature technology, seismic isolation systems can be applied to NPP facilities in areas of high seismicity. Two reactor buildings are discussed, representing the PWR and BWR buildings in Japan, and the application of seismic isolation systems is discussed. The isolation system employing rubber bearings with a lead plug positioned (LRB) is examined. Through a series of seismic response analyses using the so-named standard design earthquake motions covering the design basis earthquake motions obtained for NPP sites in Japan, the responses of the seismic isolated reactor buildings are evaluated. It is revealed that for the building structures examined herein: (1) the responses of both isolated buildings and isolating LRBs fulfill the specified design criteria; (2) the responses obtained for the isolating LRBs first reach the ultimate condition when intensity of motion is 2.0 to 2.5 times as large as that of the design-basis; and (3) the responses of isolated reactor building fall below the range of the prescribed criteria.

Supports for shock, vibration and seismic isolation for tube networks

International Nuclear Information System (INIS)

Prisecaru, Ilie; Serban, Viorel; Sandrea Madalina

2005-01-01

The paper presents a solution for diminishing the shocks, vibrations and seismic movements in pipe networks, with a simultaneous reduction in the general stress conditions in piping and supports. Total removal or reduction of vibrations is a hard problem which was not yet tackled either theoretically, in the sense of an analytical procedure for the analysis of occurrence and development of shocks and vibrations in complex systems, or practically, since the current supports and dampers cannot provide enough damping within all the frequency ranges met in the technical domain. Stiffness of classical supports do not allow always satisfactory source isolation to prevent propagation from environment of shocks and vibrations, Considering the actual condition met in the nuclear power plants, power plants and thermal power plants, etc. this paper represents a major practical aid because it provides new solutions for diminishing shocks, vibrations and seismic movements. Aiming at diminishing the effects of vibrations in pipe networks, this paper presents the results obtained in the design, construction and testing of new types of supports that include sandwich type components made up of elastic blade packages with controlled distortion provided by the central and peripheral stiff parts called SERB. With the new type of supports, the control of the distortion at static and dynamic loads and the thermal displacements is achieved by the relative movement among the sandwich structure subassemblies and by the sandwich structure distortion controlled by the central and peripheral distorting parts that generate a non - linear geometric response which has an easily controllable stiffness and damping, due to their non - linear geometric behavior. The supports of the new type are adjustable to the load and distortion level without overstressing the component material, due to a non - linear geometric behavior while the contact pressure among the blades is limited to pre-set values. Due

Dark Fiber and Distributed Acoustic Sensing: Applications to Monitoring Seismicity and Near-Surface Properties

Science.gov (United States)

Ajo Franklin, J. B.; Lindsey, N.; Dou, S.; Freifeld, B. M.; Daley, T. M.; Tracy, C.; Monga, I.

2017-12-01

"Dark Fiber" refers to the large number of fiber-optic lines installed for telecommunication purposes but not currently utilized. With the advent of distributed acoustic sensing (DAS), these unused fibers have the potential to become a seismic sensing network with unparalleled spatial extent and density with applications to monitoring both natural seismicity as well as near-surface soil properties. While the utility of DAS for seismic monitoring has now been conclusively shown on built-for-purpose networks, dark fiber deployments have been challenged by the heterogeneity of fiber installation procedures in telecommunication as well as access limitations. However, the potential of telecom networks to augment existing broadband monitoring stations provides a strong incentive to explore their utilization. We present preliminary results demonstrating the application of DAS to seismic monitoring on a 20 km run of "dark" telecommunications fiber between West Sacramento, CA and Woodland CA, part of the Dark Fiber Testbed maintained by the DOE's ESnet user facility. We show a small catalog of local and regional earthquakes detected by the array and evaluate fiber coupling by using variations in recorded frequency content. Considering the low density of broadband stations across much of the Sacramento Basin, such DAS recordings could provide a crucial data source to constrain small-magnitude local events. We also demonstrate the application of ambient noise interferometry using DAS-recorded waveforms to estimate soil properties under selected sections of the dark fiber transect; the success of this test suggests that the network could be utilized for environmental monitoring at the basin scale. The combination of these two examples demonstrates the exciting potential for combining DAS with ubiquitous dark fiber to greatly extend the reach of existing seismic monitoring networks.

Seismicity Pattern and Fault Structure in the Central Himalaya Seismic Gap Using Precise Earthquake Hypocenters and their Source Parameters

Science.gov (United States)

Mendoza, M.; Ghosh, A.; Rai, S. S.

2017-12-01

The devastation brought on by the Mw 7.8 Gorkha earthquake in Nepal on 25 April 2015, reconditioned people to the high earthquake risk along the Himalayan arc. It is therefore imperative to learn from the Gorkha earthquake, and gain a better understanding of the state of stress in this fault regime, in order to identify areas that could produce the next devastating earthquake. Here, we focus on what is known as the "central Himalaya seismic gap". It is located in Uttarakhand, India, west of Nepal, where a large (> Mw 7.0) earthquake has not occurred for over the past 200 years [Rajendran, C.P., & Rajendran, K., 2005]. This 500 - 800 km long along-strike seismic gap has been poorly studied, mainly due to the lack of modern and dense instrumentation. It is especially concerning since it surrounds densely populated cities, such as New Delhi. In this study, we analyze a rich seismic dataset from a dense network consisting of 50 broadband stations, that operated between 2005 and 2012. We use the STA/LTA filter technique to detect earthquake phases, and the latest tools contributed to the Antelope software environment, to develop a large and robust earthquake catalog containing thousands of precise hypocentral locations, magnitudes, and focal mechanisms. By refining those locations in HypoDD [Waldhauser & Ellsworth, 2000] to form a tighter cluster of events using relative relocation, we can potentially illustrate fault structures in this region with high resolution. Additionally, using ZMAP [Weimer, S., 2001], we perform a variety of statistical analyses to understand the variability and nature of seismicity occurring in the region. Generating a large and consistent earthquake catalog not only brings to light the physical processes controlling the earthquake cycle in an Himalayan seismogenic zone, it also illustrates how stresses are building up along the décollment and the faults that stem from it. With this new catalog, we aim to reveal fault structure, study

Using Seismic Interferometry to Investigate Seismic Swarms

Science.gov (United States)

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

2017-12-01

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

Distance effects on regional discriminants along a seismic profile in Northwest Nevada; NPE and nuclear results

Energy Technology Data Exchange (ETDEWEB)

McCormack, D.A. [AWE Blacknest, Berkshire (United Kingdom); Priestley, K.F. [Univ. of Cambridge (United Kingdom); Patton, H.J. [Lawrence Livermore National Lab., CA (United States)

1994-12-31

To address questions of discriminant transportability, it is important to understand how discriminants based on regional seismic phases are affected by regional variations in velocity structure. To examine this issue, we have recorded two explosions, the nuclear explosion Kinibito and the Non-Proliferation Experiment along a 300 km-long profile through western Nevada. We use these data to investigate the stability with distance of several proposed seismic discriminants. In this study we first estimate the apparent attenuation of the regional phases. We compare attenuation corrected amplitude ratios for P{sub n}/L{sub g} and P{sub g}/L{sub g}, and spectral ratios for P{sub n}, P{sub g}, and L{sub g}, as a function of distance along the profile. We make these comparisons for the vertical component and for the total vector resultant using all three components of motion.

Induced Seismicity Monitoring System

Science.gov (United States)

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

2014-12-01

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

Second Quarter Hanford Seismic Report for Fiscal Year 2009

International Nuclear Information System (INIS)

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

2009-01-01

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

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

The Central and Eastern European Earthquake Research Network - CE3RN

Science.gov (United States)

Bragato, Pier Luigi; Costa, Giovanni; Gallo, Antonella; Gosar, Andrej; Horn, Nikolaus; Lenhardt, Wolfgang; Mucciarelli, Marco; Pesaresi, Damiano; Steiner, Rudolf; Suhadolc, Peter; Tiberi, Lara; Živčić, Mladen; Zoppé, Giuliana

2014-05-01

The region of the Central and Eastern Europe is an area characterised by a relatively high seismicity. The active seismogenic structures and the related potentially destructive events are located in the proximity of the political boundaries between several countries existing in the area. An example is the seismic region between the NE Italy (FVG, Trentino-Alto Adige and Veneto), Austria (Tyrol, Carinthia) and Slovenia. So when a destructive earthquake occurs in the area, all the three countries are involved. In the year 2001 the Agencija Republike Slovenije za Okolje (ARSO) in Slovenia, the Department of Mathematics and Geoscience of the University of Trieste (DMG), the OGS (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale) in Italy and the Zentralanstalt für Meteorologie und Geodynamik (ZAMG) in Austria signed an agreement for the real-time seismological data exchange in the Southeastern Alps region. Soon after the Interreg IIIa Italia-Austria projects "Trans-National Seismological Networks in the South-Eastern Alps" and "FASTLINK" started. The main goal of these projects was the creation of a transfrontier network for the common seismic monitoring of the region for scientific and civil defense purposes. During these years the high quality data recorded by the transfrontier network has been used, by the involved institutions, for their scientific research, for institutional activities and for the civil defense services. Several common international projects have been realized with success. The instrumentation has been continuously upgraded, the installations quality improved as well as the data transmission efficiency. In the 2013 ARSO, DMG, OGS and ZAMG decided to name the cooperative network "Central and Eastern European Earthquake Research Network - CE3RN". The national/regional seismic networks actually involved in the CE3RN network are: • Austrian national BB network (ZAMG - OE) • Friuli Veneto SP network (OGS - FV) • Friuli VG

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.

Seismic Tomography in Reykjanes , SW Iceland

NARCIS (Netherlands)

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

2016-01-01

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

Angola Seismicity MAP

Science.gov (United States)

Neto, F. A. P.; Franca, G.

2014-12-01

The purpose of this job was to study and document the Angola natural seismicity, establishment of the first database seismic data to facilitate consultation and search for information on seismic activity in the country. The study was conducted based on query reports produced by National Institute of Meteorology and Geophysics (INAMET) 1968 to 2014 with emphasis to the work presented by Moreira (1968), that defined six seismogenic zones from macro seismic data, with highlighting is Zone of Sá da Bandeira (Lubango)-Chibemba-Oncócua-Iona. This is the most important of Angola seismic zone, covering the epicentral Quihita and Iona regions, geologically characterized by transcontinental structure tectono-magmatic activation of the Mesozoic with the installation of a wide variety of intrusive rocks of ultrabasic-alkaline composition, basic and alkaline, kimberlites and carbonatites, strongly marked by intense tectonism, presenting with several faults and fractures (locally called corredor de Lucapa). The earthquake of May 9, 1948 reached intensity VI on the Mercalli-Sieberg scale (MCS) in the locality of Quihita, and seismic active of Iona January 15, 1964, the main shock hit the grade VI-VII. Although not having significant seismicity rate can not be neglected, the other five zone are: Cassongue-Ganda-Massano de Amorim; Lola-Quilengues-Caluquembe; Gago Coutinho-zone; Cuima-Cachingues-Cambândua; The Upper Zambezi zone. We also analyzed technical reports on the seismicity of the middle Kwanza produced by Hidroproekt (GAMEK) region as well as international seismic bulletins of the International Seismological Centre (ISC), United States Geological Survey (USGS), and these data served for instrumental location of the epicenters. All compiled information made possible the creation of the First datbase of seismic data for Angola, preparing the map of seismicity with the reconfirmation of the main seismic zones defined by Moreira (1968) and the identification of a new seismic

The monterey bay broadband ocean bottom seismic observatory

Directory of Open Access Journals (Sweden)

R. Uhrhammer

2006-06-01

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

Full-waveform seismic tomography of the Vrancea, Romania, subduction region

Science.gov (United States)

Baron, Julie; Morelli, Andrea

2017-12-01

The Vrancea region is one of the few locations of deep seismicity in Europe. Seismic tomography has been able to map lithospheric downwelling, but has not been able yet to clearly discriminate between competing geodynamic interpretations of the geological and geophysical evidence available. We study the seismic structure of the Vrancea subduction zone, using adjoint-based, full-waveform tomography to map the 3D vP and vS structure in detail. We use the database that was built during the CALIXTO (Carpathian Arc Lithosphere X-Tomography) temporary experiment, restricted to the broadband sensors and local intermediate-depth events. We fit waveforms with a cross-correlation misfit criterion in separate time windows around the expected P and S arrivals, and perform 17 iterations of vP and vS model updates (altogether, requiring about 16 million CPU hours) before reaching stable convergence. Among other features, our resulting model shows a nearly vertical, high-velocity body, that overlaps with the distribution of seismicity in its northeastern part. In its southwestern part, a slab appears to dip less steeply to the NW, and is suggestive of ongoing - or recently concluded - subduction geodynamic processes. Joint inversion for vP and vS allow us to address the vP/vS ratio distribution, that marks high vP/vS in the crust beneath the Focsani sedimentary basin - possibly due to high fluid pressure - and a low vP/vS edge along the lower plane of the subducting lithosphere, that in other similar environment has been attributed to dehydration of serpentine in the slab. In spite of the restricted amount of data available, and limitations on the usable frequency pass-band, full-waveform inversion reveals its potential to improve the general quality of imaging with respect to other tomographic techniques - although at a sensible cost in terms of computing resources. Our study also shows that re-analysis of legacy data sets with up-to-date techniques may bring new, useful

Yield Estimation for Semipalatinsk Underground Nuclear Explosions Using Seismic Surface-wave Observations at Near-regional Distances

Science.gov (United States)

Adushkin, V. V.

- A statistical procedure is described for estimating the yields of underground nuclear tests at the former Soviet Semipalatinsk test site using the peak amplitudes of short-period surface waves observed at near-regional distances (Δ Semipalatinsk explosions, including the Soviet JVE explosion of September 14, 1988, and it is demonstrated that it provides seismic estimates of explosion yield which are typically within 20% of the yields determined for these same explosions using more accurate, non-seismic techniques based on near-source observations.

New Ground Motion Prediction Models for Caucasus Region

Science.gov (United States)

Jorjiashvili, N.

2012-12-01

The Caucasus is a region of numerous natural hazards and ensuing disasters. Analysis of the losses due to past disasters indicates the those most catastrophic in the region have historically been due to strong earthquakes. Estimation of expected ground motion is a fundamental earthquake hazard assessment. The most commonly used parameter for attenuation relation is peak ground acceleration because this parameter gives useful information for Seismic Hazard Assessment. Because of this, many peak ground acceleration attenuation relations have been developed by different authors. Besides, a few attenuation relations were developed for Caucasus region: Ambraseys et al. (1996,2005) which were based on entire European region and they were not focused locally on Caucasus Region; Smit et.al. (2000) that was based on a small amount of acceleration data that really is not enough. Since 2003 construction of Georgian Digital Seismic Network has started with the help of number of International organizations, Projects and Private companies. The works conducted involved scientific as well as organizational activities: Resolving technical problems concerning communication and data transmission. Thus, today we have a possibility to get real time data and make scientific research based on digital seismic data. Generally, ground motion and damage are influenced by the magnitude of the earthquake, the distance from the seismic source to site, the local ground conditions and the characteristics of buildings. Estimation of expected ground motion is a fundamental earthquake hazard assessment. This is the reason why this topic is emphasized in this study. In this study new GMP models are obtained based on new data from Georgian seismic network and also from neighboring countries. Estimation of models are obtained by classical, statistical way, regression analysis. Also site ground conditions are considered because the same earthquake recorded at the same distance may cause different damage

Radiated Seismic Energy of Earthquakes in the South-Central Region of the Gulf of California, Mexico

Science.gov (United States)

Castro, Raúl R.; Mendoza-Camberos, Antonio; Pérez-Vertti, Arturo

2018-05-01

We estimated the radiated seismic energy (ES) of 65 earthquakes located in the south-central region of the Gulf of California. Most of these events occurred along active transform faults that define the Pacific-North America plate boundary and have magnitudes between M3.3 and M5.9. We corrected the spectral records for attenuation using nonparametric S-wave attenuation functions determined with the whole data set. The path effects were isolated from the seismic source using a spectral inversion. We computed radiated seismic energy of the earthquakes by integrating the square velocity source spectrum and estimated their apparent stresses. We found that most events have apparent stress between 3 × 10-4 and 3 MPa. Model independent estimates of the ratio between seismic energy and moment (ES/M0) indicates that this ratio is independent of earthquake size. We conclude that in general the apparent stress is low (σa < 3 MPa) in the south-central and southern Gulf of California.

Calibration of Seismic Attributes for Reservoir Characterization

Energy Technology Data Exchange (ETDEWEB)

Pennington, Wayne D.; Acevedo, Horacio; Green, Aaron; Len, Shawn; Minavea, Anastasia; Wood, James; Xie, Deyi

2002-01-29

This project has completed the initially scheduled third year of the contract, and is beginning a fourth year, designed to expand upon the tech transfer aspects of the project. From the Stratton data set, demonstrated that an apparent correlation between attributes derived along `phantom' horizons are artifacts of isopach changes; only if the interpreter understands that the interpretation is based on this correlation with bed thickening or thinning, can reliable interpretations of channel horizons and facies be made. From the Boonsville data set , developed techniques to use conventional seismic attributes, including seismic facies generated under various neural network procedures, to subdivide regional facies determined from logs into productive and non-productive subfacies, and developed a method involving cross-correlation of seismic waveforms to provide a reliable map of the various facies present in the area. The Teal South data set provided a surprising set of data, leading us to develop a pressure-dependent velocity relationship and to conclude that nearby reservoirs are undergoing a pressure drop in response to the production of the main reservoir, implying that oil is being lost through their spill points, never to be produced. The Wamsutter data set led to the use of unconventional attributes including lateral incoherence and horizon-dependent impedance variations to indicate regions of former sand bars and current high pressure, respectively, and to evaluation of various upscaling routines.

Origins of a national seismic system in the United States

Science.gov (United States)

Filson, John R.; Arabasz, Walter J.

2016-01-01

This historical review traces the origins of the current national seismic system in the United States, a cooperative effort that unifies national, regional, and local‐scale seismic monitoring within the structure of the Advanced National Seismic System (ANSS). The review covers (1) the history and technological evolution of U.S. seismic networks leading up to the 1990s, (2) factors that made the 1960s and 1970s a watershed period for national attention to seismology, earthquake hazards, and seismic monitoring, (3) genesis of the vision of a national seismic system during 1980–1983, (4) obstacles and breakthroughs during 1984–1989, (5) consensus building and convergence during 1990–1992, and finally (6) the two‐step realization of a national system during 1993–2000. Particular importance is placed on developments during the period between 1980 and 1993 that culminated in the adoption of a charter for the Council of the National Seismic System (CNSS)—the foundation for the later ANSS. Central to this story is how many individuals worked together toward a common goal of a more rational and sustainable approach to national earthquake monitoring in the United States. The review ends with the emergence of ANSS during 1999 and 2000 and its statutory authorization by Congress in November 2000.

Seismic monitoring experiment of raise boring in 2014

International Nuclear Information System (INIS)

Saari, J.; Malm, M.

2015-01-01

In Olkiluoto, Posiva Oy has operated a local seismic network since February 2002. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The studies include both tectonic and excavation-induced microearthquakes. An additional task of monitoring is related to safeguarding of ONKALO. The possibility to excavate an illegal access to ONKALO has been concerned when the safeguards are discussed. Therefore all recorded explosions in the Olkiluoto area and in ONKALO are located. If a concentration of explosions is observed, the origin of that is found out. Also a concept of hidden illegal explosions, detonated at the same time as the real excavation blasts, has been examined. According to the experience gained in Olkiluoto, it can be concluded that, as long the seismic network is in operation and the results are analysed by a skilled person, it is practically impossible to do illegal undetected excavation by blasting within the Olkiluoto seismic network area. In this report a possibility of seismic monitoring of undeclared excavation done by tunnel boring machine (TBM) has been investigated. In the earlier investigations the instruments were at the ground surface and the sensors were triaxial short period (1 Hz) geophones or broadband geophones. The characteristics (frequency content, polarity and amplitude) of the continuous seismic vibration generated by TMB were studied. The onset time of the seismic signal were not distinguished. Altogether 16 new 10 kHz accelerometers were installed in boreholes inside ONKALO March 2012. The sensors comprised a new subnetwork that monitored the raise boring of two shafts done 2014, from the level -455 m to the level -290 m. The aim was to record the seismic signal generated when the drill bit hits the rock at the moment the tunnel boring begins. Altogether 113 seismic signals generated by the drill bit were located during the

Seismic monitoring experiment of raise boring in 2014

Energy Technology Data Exchange (ETDEWEB)

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

2015-01-15

In Olkiluoto, Posiva Oy has operated a local seismic network since February 2002. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The studies include both tectonic and excavation-induced microearthquakes. An additional task of monitoring is related to safeguarding of ONKALO. The possibility to excavate an illegal access to ONKALO has been concerned when the safeguards are discussed. Therefore all recorded explosions in the Olkiluoto area and in ONKALO are located. If a concentration of explosions is observed, the origin of that is found out. Also a concept of hidden illegal explosions, detonated at the same time as the real excavation blasts, has been examined. According to the experience gained in Olkiluoto, it can be concluded that, as long the seismic network is in operation and the results are analysed by a skilled person, it is practically impossible to do illegal undetected excavation by blasting within the Olkiluoto seismic network area. In this report a possibility of seismic monitoring of undeclared excavation done by tunnel boring machine (TBM) has been investigated. In the earlier investigations the instruments were at the ground surface and the sensors were triaxial short period (1 Hz) geophones or broadband geophones. The characteristics (frequency content, polarity and amplitude) of the continuous seismic vibration generated by TMB were studied. The onset time of the seismic signal were not distinguished. Altogether 16 new 10 kHz accelerometers were installed in boreholes inside ONKALO March 2012. The sensors comprised a new subnetwork that monitored the raise boring of two shafts done 2014, from the level -455 m to the level -290 m. The aim was to record the seismic signal generated when the drill bit hits the rock at the moment the tunnel boring begins. Altogether 113 seismic signals generated by the drill bit were located during the

Regional Use of Social Networking Tools

Science.gov (United States)

2014-12-01

4 2.1.7 Tumblr 4 2.1.8 Instagram 4 2.2 Local Social Networking Services 5 3 Regional Preferences for Social Networking Tools 6 4 African Region...YouTube 280 million Twitter 255 million LinkedIn n/a Pinterest n/a Tumblr 300 million Instagram 200 million The active-user base numbers...so this percentage may decline in the future. 2.1.8 Instagram Instagram , acquired by Facebook in 2012, is a mobile social networking service that

Seismicity and crustal structure at the Mendocino triple junction, Northern California

Energy Technology Data Exchange (ETDEWEB)

Dicke, M.

1998-12-01

A high level of seismicity at the Mendocino triple junction in Northern California reflects the complex active tectonics associated with the junction of the Pacific, North America, and Gorda plates. To investigate seismicity patterns and crustal structure, 6193 earthquakes recorded by the Northern California Seismic Network (NCSN) are relocated using a one-dimensional crustal velocity model. A near vertical truncation of the intense seismic activity offshore Cape Mendocino follows the strike of the Mattole Canyon fault and is interpreted to define the Pacific plate boundary. Seismicity along this boundary displays a double seismogenic layer that is attributed to interplate activity with the North America plate and Gorda plate. The interpretation of the shallow seismogenic zone as the North America - Pacific plate boundary implies that the Mendocino triple junction is situated offshore at present. Seismicity patterns and focal mechanisms for events located within the subducting Gorda pl ate are consistent with internal deformation on NE-SW and NW-SE trending rupture planes in response to north-south compression. Seismic sections indicate that the top of the Gorda plate locates at a depth of about 18 Km beneath Cape Mendocino and dips gently east-and southward. Earthquakes that are located in the Wadati-Benioff zone east of 236{sup o}E show a change to an extensional stress regime indicative of a slab pull force. This slab pull force and scattered seismicity within the contractional forearc region of the Cascadia subduction zone suggest that the subducting Gorda plate and the overriding North America plate are strongly coupled. The 1992 Cape Mendocino thrust earthquake is believed to have ruptured a blind thrust fault in the forearc region, suggesting that strain is accumulating that must ultimately be released in a potential M 8+ subduction earthquake.

Method for identifying subsurface fluid migration and drainage pathways in and among oil and gas reservoirs using 3-D and 4-D seismic imaging

Science.gov (United States)

Anderson, R.N.; Boulanger, A.; Bagdonas, E.P.; Xu, L.; He, W.

1996-12-17

The invention utilizes 3-D and 4-D seismic surveys as a means of deriving information useful in petroleum exploration and reservoir management. The methods use both single seismic surveys (3-D) and multiple seismic surveys separated in time (4-D) of a region of interest to determine large scale migration pathways within sedimentary basins, and fine scale drainage structure and oil-water-gas regions within individual petroleum producing reservoirs. Such structure is identified using pattern recognition tools which define the regions of interest. The 4-D seismic data sets may be used for data completion for large scale structure where time intervals between surveys do not allow for dynamic evolution. The 4-D seismic data sets also may be used to find variations over time of small scale structure within individual reservoirs which may be used to identify petroleum drainage pathways, oil-water-gas regions and, hence, attractive drilling targets. After spatial orientation, and amplitude and frequency matching of the multiple seismic data sets, High Amplitude Event (HAE) regions consistent with the presence of petroleum are identified using seismic attribute analysis. High Amplitude Regions are grown and interconnected to establish plumbing networks on the large scale and reservoir structure on the small scale. Small scale variations over time between seismic surveys within individual reservoirs are identified and used to identify drainage patterns and bypassed petroleum to be recovered. The location of such drainage patterns and bypassed petroleum may be used to site wells. 22 figs.

Geothermal Heat Flux and Upper Mantle Viscosity across West Antarctica: Insights from the UKANET and POLENET Seismic Networks

Science.gov (United States)

O'Donnell, J. P.; Dunham, C.; Stuart, G. W.; Brisbourne, A.; Nield, G. A.; Whitehouse, P. L.; Hooper, A. J.; Nyblade, A.; Wiens, D.; Aster, R. C.; Anandakrishnan, S.; Huerta, A. D.; Wilson, T. J.; Winberry, J. P.

2017-12-01

Quantifying the geothermal heat flux at the base of ice sheets is necessary to understand their dynamics and evolution. The heat flux is a composite function of concentration of upper crustal radiogenic elements and flow of heat from the mantle into the crust. Radiogenic element concentration varies with tectonothermal age, while heat flow across the crust-mantle boundary depends on crustal and lithospheric thicknesses. Meanwhile, accurately monitoring current ice mass loss via satellite gravimetry or altimetry hinges on knowing the upper mantle viscosity structure needed to account for the superimposed glacial isostatic adjustment (GIA) signal in the satellite data. In early 2016 the UK Antarctic Network (UKANET) of 10 broadband seismometers was deployed for two years across the southern Antarctic Peninsula and Ellsworth Land. Using UKANET data in conjunction with seismic records from our partner US Polar Earth Observing Network (POLENET) and the Antarctic Seismographic Argentinian Italian Network (ASAIN), we have developed a 3D shear wave velocity model of the West Antarctic crust and uppermost mantle based on Rayleigh and Love wave phase velocity dispersion curves extracted from ambient noise cross-correlograms. We combine seismic receiver functions with the shear wave model to help constrain the depth to the crust-mantle boundary across West Antarctica and delineate tectonic domains. The shear wave model is subsequently converted to temperature using a database of densities and elastic properties of minerals common in crustal and mantle rocks, while the various tectonic domains are assigned upper crustal radiogenic element concentrations based on their inferred tectonothermal ages. We combine this information to map the basal geothermal heat flux variation across West Antarctica. Mantle viscosity depends on factors including temperature, grain size, the hydrogen content of olivine and the presence of melt. Using published mantle xenolith and magnetotelluric

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

Science.gov (United States)

Wiejacz, Paweł; Wiszniowski, Jan

2006-03-01

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