Investigating Brittle Rock Failure and Associated Seismicity Using Laboratory Experiments and Numerical Simulations

NASA Astrophysics Data System (ADS)

Zhao, Qi

Rock failure process is a complex phenomenon that involves elastic and plastic deformation, microscopic cracking, macroscopic fracturing, and frictional slipping of fractures. Understanding this complex behaviour has been the focus of a significant amount of research. In this work, the combined finite-discrete element method (FDEM) was first employed to study (1) the influence of rock discontinuities on hydraulic fracturing and associated seismicity and (2) the influence of in-situ stress on seismic behaviour. Simulated seismic events were analyzed using post-processing tools including frequency-magnitude distribution (b-value), spatial fractal dimension (D-value), seismic rate, and fracture clustering. These simulations demonstrated that at the local scale, fractures tended to propagate following the rock mass discontinuities; while at reservoir scale, they developed in the direction parallel to the maximum in-situ stress. Moreover, seismic signature (i.e., b-value, D-value, and seismic rate) can help to distinguish different phases of the failure process. The FDEM modelling technique and developed analysis tools were then coupled with laboratory experiments to further investigate the different phases of the progressive rock failure process. Firstly, a uniaxial compression experiment, monitored using a time-lapse ultrasonic tomography method, was carried out and reproduced by the numerical model. Using this combination of technologies, the entire deformation and failure processes were studied at macroscopic and microscopic scales. The results not only illustrated the rock failure and seismic behaviours at different stress levels, but also suggested several precursory behaviours indicating the catastrophic failure of the rock. Secondly, rotary shear experiments were conducted using a newly developed rock physics experimental apparatus ERDmu-T) that was paired with X-ray micro-computed tomography (muCT). This combination of technologies has significant advantages

Investigating the Origin of Seismic Swarms

NASA Astrophysics Data System (ADS)

Govoni, Aladino; Passarelli, Luigi; Braun, Thomas; Maccaferri, Francesco; Moretti, Milena; Lucente, Francesco Pio; Rivalta, Eleonora; Cesca, Simone; Hainzl, Sebastian; Woith, Heiko; De Gori, Pasquale; Dahm, Torsten; Chiarabba, Claudio; Margheriti, Lucia

2013-10-01

According to the U.S. Geological Survey's Earthquake Hazards Program, a seismic swarm is "a localized surge of earthquakes, with no one shock being conspicuously larger than all other shocks of the swarm. They might occur in a variety of geologic environments and are not known to be indicative of any change in the long-term seismic risk of the region in which they occur" (http://vulcan.wr.usgs.gov/Glossary/Seismicity/description_earthquakes.html).

Reassessment of the Seismicity and seismic hazards of Libya

NASA Astrophysics Data System (ADS)

Ben Suleman, A.; Elmeladi, A.

2009-04-01

The tectonic evolution of Libya, located at the northern extreme of the African continent, has yielded a complex crustal structure that is composed of a series of basins and uplifts. The present day deformation of Libya is the result of the Eurasia-Africa continental collision. At the end of the year 2005, The Libyan National Seismological Network was established to monitor local, regional and teleseismic activities, as well as to provide high quality data for research projects both locally and on the regional and global scale. This study aims to discuss the seismicity of Libya by using the new data from the Libyan national seismological network and to focus on the seismic hazards. At first glance the seismic activity map shows dominant trends of seismicity with most of the seismic activity concentrated along the northern coastal areas. Four major seismic trends were quite noticeable. A first trend is a NW-SE direction coinciding with the eastern boarder of the Hun Graben. A second trend is also a NW-SE direction in the offshore area and might be a continuation of this trend. The other two trends were located in the western Gulf of Sirt and Cyrenaica platform. The rest of seismicity is diffuse either offshore or in land, with no good correlation with well-mapped faults. Detailed investigations of the Libyan seismicity indicates that the Libya has experienced earthquakes of varying magnitudes and that there is definitely a certain amount of seismic risk involved in engineering projects, particularly in the northern regions. Detailed investigation of the distribution of the Libyan earthquakes in space and time along with all other geological considerations suggested the classification of the country into four seismic zones with the Hun graben zone being the most seismically active zone.

Coherent Waves in Seismic Researches

NASA Astrophysics Data System (ADS)

Emanov, A.; Seleznev, V. S.

2013-05-01

reflected waves. With use of developed algorithms of head wave conversion in time sections a work of studying of refracting boundaries in Siberia have been executed. Except for the research by method of refracting waves, the conversion of head waves in time sections, applied to seismograms of reflected wave method, allows to obtain information about refracting horizons in upper part of section in addition to reflecting horizons data. Recovery method of wave field coherent components is the basis of the engineering seismology on the level of accuracy and detail. In seismic microzoning resonance frequency of the upper part of section are determined on the basis of this method. Maps of oscillation amplification and result accuracy are constructed for each of the frequencies. The same method makes it possible to study standing wave field in buildings and constructions with high accuracy and detail, realizing diagnostics of their physical state on set of natural frequencies and form of self-oscillations, examined with high detail. The method of standing waves permits to estimate a seismic stability of structure on new accuracy level.

The Investigation of a Sinkhole Area in Germany by Near-Surface Active Seismic Tomography

NASA Astrophysics Data System (ADS)

Tschache, S.; Becker, D.; Wadas, S. H.; Polom, U.; Krawczyk, C. M.

2017-12-01

In November 2010, a 30 m wide and 17 m deep sinkhole occurred in a residential area of Schmalkalden, Germany, which fortunately did not harm humans, but led to damage of buildings and property. Subsequent geoscientific investigations showed that the collapse was naturally caused by the subrosion of sulfates in a depth of about 80 m. In 2012, an early warning system was established including 3C borehole geophones deployed in 50 m depth around the backfilled sinkhole. During the acquisition of two shallow 2D shear wave seismic profiles, the signals generated by a micro-vibrator at the surface were additionally recorded by the four borehole geophones of the early warning system and a VSP probe in a fifth borehole. The travel time analysis of the direct arrivals enhanced the understanding of wave propagation in the area. Seismic velocity anomalies were detected and related to structural seismic images of the 2D profiles. Due to the promising first results, the experiment was further extended by distributing vibration points throughout the whole area around the sinkhole. This time, micro-vibrators for P- and S-wave generation were used. The signals were recorded by the borehole geophones and temporary installed seismometers at surface positions close to the boreholes. The travel times and signal attenuations are evaluated to detect potential instable zones. Furthermore, array analyses are performed. The first results reveal features in the active tomography datasets consistent with structures observed in the 2D seismic images. The advantages of the presented method are the low effort and good repeatability due to the permanently installed borehole geophones. It has the potential to determine P-wave and S-wave velocities in 3D. It supports the interpretation of established investigation methods as 2D surface seismics and VSP. In our further research we propose to evaluate the suitability of the method for the time lapse monitoring of changes in the seismic wave

A 3-D seismic investigation of the Ray gas storage reef, Macomb County, Michigan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaefer, S.F.; Dixon, R.A.

1994-08-01

A 4.2 mi[sup 2] 3-D seismic survey was acquired over the Ray Niagaran reef gas storage field in southeast Michigan as part of a program to maximize storage capacity and gas deliverability of the storage reservoir. Goals of the survey were to (1) determine if additional storage capacity could be found either as extensions to the Ray reef or as undiscovered satellite reefs, (2) investigate the relationship between the main body and a low-relief gas well east of the reef, and (3) determine if seismic data can be used to quantify reservoir parameters to maximize the productive capacity of infillmore » wells. Interpretation of the 3-D seismic data resulted in a detailed image of the reef, using several interpretive techniques. A seismic reflection within the reef was correlated with a known porosity zone, and a possible relationship between porosity and seismic amplitude was investigated. A potential connection between the main reef and the low-relief gas well was identified. This project illustrates the economic value of investigating an existing storage reef with 3-D seismic data, and underscores the necessity of such a survey prior to developing a new storage reservoir.« less

Seismic investigations in downtown Copenhagen, Denmark

NASA Astrophysics Data System (ADS)

Martinez, K.; Mendoza, J. A.; Olsen, H.

2009-12-01

Near surface geophysics are gaining widespread use in major infrastructure projects with respect to geotechnical and engineering applications. The development of data acquisition, processing tools and interpretation methods have optimized survey production, reduced logistics costs and increase results reliability of seismic surveys during the last decades. However, the use of geophysical methods under urban environments continues to face challenges due to multiple noise sources and obstacles inherent to cities. A seismic investigation was conducted in Copenhagen aiming to produce information needed for hydrological, geotechnical and groundwater modeling assessments related to the planned Cityringen underground metro project. The particular objectives were a) map variations in subsurface Quaternary and limestone properties b) to map for near surface structural features. The geological setting in the Copenhagen region is characterized by several interlaced layers of glacial till and meltwater sand deposits. These layers, which are found unevenly distributed throughout the city and present in varying thicknesses, overlie limestone of different generations. There are common occurrences of incised valley structures containing localized instances of weathered or fractured limestone. The surveys consisted of combined seismic reflection and refraction profiles accounting for approximately 13 km along sections of the projected metro line. The data acquisition was carried out using standard 192 channels arrays, receiver groups with 5 m spacing and a Vibroseis as a source at 5 m spacing. In order to improve the resolution of the data, 29 Walkaway-Vertical Seismic Profiles were performed at selected wells along the surface seismic lines. The refraction data was processed with travel-time tomography and the reflection data underwent standard interpretation. The refraction data inversion was performed twofold; a surface refraction alone and combined with the VSP data. Three

Very-high-resolution seismic and magnetic investigations of a chemical munition dumpsite in the Baltic Sea

NASA Astrophysics Data System (ADS)

Missiaen, Tine; Feller, Pascal

2008-09-01

Very-high-resolution (VHR) seismic and magnetic investigations were carried out over a chemical munition dumpsite in the Bornholm Basin, south-western Baltic Sea. The main goal of the investigations was to image the shallow internal structure of the dumpsite and to map the lateral and vertical distribution of the dumped war material. The shallow geology was imaged in great detail on the seismic data. Seven seismic-stratigraphic units were identified, related to different stages in the Holocene and late-glacial history. A large number of diapir-like features were observed that most likely represent fluid expulsion phenomena. Four shipwrecks were identified in the dumpsite area. The wrecks have partly sunk into the soft upper sediments, their height above the sea floor reaching no more than 2 m. Seismic and magnetic data indicate the presence of a large number of buried objects. In most cases there is a good correlation between the seismic and magnetic data sets. The objects are generally buried no deeper than 1 to 2 m. Their size varies between 1.5 and 5 m, occasionally up to 10 m. Shallow pits in the sea bed are likely due to the impact of dumping. The data confirm the wide variety of dumped war material ranging from bombs and shells to encasements and containers. The distribution of the buried objects seems rather heterogeneous, with locally high object concentrations surrounded by areas of lower object density. The results of this case study demonstrate the benefit of complementary, concurrent geophysical investigations for munition dumpsite research. Finally this will yield a better assessment of the current status of the dumpsite and the possible ecological risks related to the dumped war material.

Seismic response of rock slopes: Numerical investigations on the role of internal structure

NASA Astrophysics Data System (ADS)

Arnold, L.; Applegate, K.; Gibson, M.; Wartman, J.; Adams, S.; Maclaughlin, M.; Smith, S.; Keefer, D. K.

2013-12-01

The stability of rock slopes is significantly influenced and often controlled by the internal structure of the slope created by such discontinuities as joints, shear zones, and faults. Under seismic conditions, these discontinuities influence both the resistance of a slope to failure and its response to dynamic loading. The dynamic response, which can be characterized by the slope's natural frequency and amplification of ground motion, governs the loading experienced by the slope in a seismic event and, therefore, influences the slope's stability. In support of the Network for Earthquake Engineering Simulation (NEES) project Seismically-Induced Rock Slope Failure: Mechanisms and Prediction (NEESROCK), we conducted a 2D numerical investigation using the discrete element method (DEM) coupled with simple discrete fracture networks (DFNs). The intact rock mass is simulated with a bonded assembly of discrete particles, commonly referred to as the bonded-particle model (BPM) for rock. Discontinuities in the BPM are formed by the insertion of smooth, unbonded contacts along specified planes. The influence of discontinuity spacing, orientation, and stiffness on slope natural frequency and amplification was investigated with the commercially available Particle Flow Code (PFC2D). Numerical results indicate that increased discontinuity spacing has a non-linear effect in decreasing the amplification and increasing the natural frequency of the slope. As discontinuity dip changes from sub-horizontal to sub-vertical, the slope's level of amplification increases while the natural frequency of the slope decreases. Increased joint stiffness decreases amplification and increases natural frequency. The results reveal that internal structure has a strong influence on rock slope dynamics that can significantly change the system's dynamic response and stability during seismic loading. Financial support for this research was provided by the United States National Science Foundation (NSF

GFZ Wireless Seismic Array (GFZ-WISE), a Wireless Mesh Network of Seismic Sensors: New Perspectives for Seismic Noise Array Investigations and Site Monitoring

PubMed Central

Picozzi, Matteo; Milkereit, Claus; Parolai, Stefano; Jaeckel, Karl-Heinz; Veit, Ingo; Fischer, Joachim; Zschau, Jochen

2010-01-01

Over the last few years, the analysis of seismic noise recorded by two dimensional arrays has been confirmed to be capable of deriving the subsoil shear-wave velocity structure down to several hundred meters depth. In fact, using just a few minutes of seismic noise recordings and combining this with the well known horizontal-to-vertical method, it has also been shown that it is possible to investigate the average one dimensional velocity structure below an array of stations in urban areas with a sufficient resolution to depths that would be prohibitive with active source array surveys, while in addition reducing the number of boreholes required to be drilled for site-effect analysis. However, the high cost of standard seismological instrumentation limits the number of sensors generally available for two-dimensional array measurements (i.e., of the order of 10), limiting the resolution in the estimated shear-wave velocity profiles. Therefore, new themes in site-effect estimation research by two-dimensional arrays involve the development and application of low-cost instrumentation, which potentially allows the performance of dense-array measurements, and the development of dedicated signal-analysis procedures for rapid and robust estimation of shear-wave velocity profiles. In this work, we present novel low-cost wireless instrumentation for dense two-dimensional ambient seismic noise array measurements that allows the real–time analysis of the surface-wavefield and the rapid estimation of the local shear-wave velocity structure for site response studies. We first introduce the general philosophy of the new system, as well as the hardware and software that forms the novel instrument, which we have tested in laboratory and field studies. PMID:22319298

100 years of seismic research on the Moho

NASA Astrophysics Data System (ADS)

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

2013-12-01

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

A 3D seismic investigation of the Ray Gas Storage Reef in Macomb County, Michigan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaefer, S.F.; Dixon, R.A.

1995-09-01

A 4.2 square mile 3D seismic survey was acquired over the Ray Niagaran Reef Gas Storage Field in southeast Michigan as part of a program to maximize storage capacity and gas deliverability of the field. Goals of the survey were: (1) to determine if additional storage capacity could be found, either as extensions to the main reef or as undiscovered satellite reefs, (2) to determine if 3D seismic data can be utilized to quantify reservoir parameters in order to maximize the productive capacity of infill wells, and (3) to investigate the relationship between the main reef body and a lowmore » relief/flow volume gas well east of the reef. Interpretation of the 3D seismic data resulted in a detailed image of the reef, using several interpretive techniques. A seismic reflection within the reef was correlated with a known porosity zone, and the relationship between porosity and seismic amplitude was investigated. A possible connection between the main reef and the low relief gas well was identified. This project illustrates the economic value of investigating an existing storage reef with 3D seismic data, and underscores the necessity of acquiring such a survey prior to developing a new storage reservoir.« less

Sismos a l'Ecole : a Seismic Educational Network (FRANCE) linked with Research

NASA Astrophysics Data System (ADS)

Berenguer, J.; Le Puth, J.; Courboulex, F.; Zodmi, B.; Boneff, M.

2007-12-01

Ahead of the quick evolution of our society, in which scientific information has to be accurately understood by a great majority, the promotion of a responsible behaviour coming from educated and trained citizens has become a priority. One of the roles of school is to enable children to understand sciences, these same sciences that were long ago the prerogative of scientific laboratories. The educational network SISMOS à l\\'"Ecole is an example of a project structured on the knowledge of seismic risks through a scientific and technological approach. It develops a teaching method leading to an approach towards the knowledge of natural disasters. The original and innovating feature of this educational network is to enable students to set up a seismograph in their school. The recorded signals - coming from a regional or a worldwide seismic activity - feed an on- line database, which is in fact a real research centre for seismic resources as well as a starting point for educational and scientific activities. The network, that numbers about thirty stations set up in France, in its overseas departments and territories, and in a couple of French schools abroad, is based upon an experience initiated in the French Riviera ten years ago or so. The achievement of the program has from then on gone beyond the simple purpose of conveying seismic data that research and monitoring centres could have recorded. Thanks to the use of scientific measures, students become involved and get into complex notions revolving around geophysics and geosciences. Developing simple tools, setting up concrete experiments combined with an investigate reasoning makes it easier to build up a quality scientific culture as well as an education of citizens to risks.

Seismic Ecology

NASA Astrophysics Data System (ADS)

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

INVESTIGATING THE EFFECT OF MICROBIAL GROWTH AND BIOFILM FORMATION ON SEISMIC WAVE PROPAGATION IN SEDIMENT

EPA Science Inventory

Previous laboratory investigations have demonstrated that the seismic methods are sensitive to microbially-induced changes in porous media through the generation of biogenic gases and biomineralization. The seismic signatures associated with microbial growth and biofilm formation...

Experimental investigation of the seismic performance of the R/C frames with reinforced masonry infills

NASA Astrophysics Data System (ADS)

Tanjung, Jafril; Maidiawati, Nugroho, Fajar

2017-10-01

Intensive studies regarding the investigation of seismic performance of reinforced concrete (R/C) frames which are infilled with brick masonry walls have been carried out by several researchers within the last three-decades. According to authors' field and experimentally experiences conclude that the unreinforced brick masonry infills significantly contributes to increase the seismic performance of the R/C frame structure. Unfortunately, the presence of brick masonry infill walls causes several undesirable effects such as short column, soft-storey, torsion and out of plane collapse. In this study, a strengthening technique for the brick masonry infills were experimentally investigated to improve the seismic performance of the R/C frame structures. For this purpose, four experimental specimens have been prepared, i.e. one of bare R/C frame (BF), one of R/C frame infilled with unreinforced brick-masonry wall (IFUM) and two of R/C frames were infilled with reinforced brick-masonry wall (IFRM-1 and IFRM-2). The bare frame and R/C frame infilled with unreinforced brick-masonry wall represents the typical R/C buildings' construction in Indonesia assuming the brick-masonry wall as the non-structural elements. The brick-masonry wall infills in specimens IFRM-1 and IFRM-2 were strengthened by using embedded ϕ4 plain steel bar on their diagonal and center of brick-masonry wall, respectively. All specimens were laterally pushed-over. The lateral loading and its lateral displacement, failure mechanism and their crack pattern were recorded during experimental works. Comparison of the experimental results of these four specimens conclude that the strengthening of the brick-masonry infills wall gave the significantly increasing of the seismic performance of the R/C frame. The seismic performance was evaluated based on the lateral strength of the R/C specimen. The embedded plain steel bar on brick-masonry also reduces the diagonal crack on the brick-masonry wall. It seems that

Application of normal mode theory to seismic source and structure problems: Seismic investigations of upper mantle lateral heterogeneity. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Okal, E. A.

1978-01-01

The theory of the normal modes of the earth is investigated and used to build synthetic seismograms in order to solve source and structural problems. A study is made of the physical properties of spheroidal modes leading to a rational classification. Two problems addressed are the observability of deep isotropic seismic sources and the investigation of the physical properties of the earth in the neighborhood of the Core-Mantle boundary, using SH waves diffracted at the core's surface. Data sets of seismic body and surface waves are used in a search for possible deep lateral heterogeneities in the mantle. In both cases, it is found that seismic data do not require structural differences between oceans and continents to extend deeper than 250 km. In general, differences between oceans and continents are found to be on the same order of magnitude as the intrinsic lateral heterogeneity in the oceanic plate brought about by the aging of the oceanic lithosphere.

Investigation of the foundations of a Byzantine church by three-dimensional seismic tomography

NASA Astrophysics Data System (ADS)

Polymenakos, L.; Papamarinopoulos, S.; Miltiadou, A.; Charkiolakis, N.

2005-02-01

Byzantine public buildings are of high historical and cultural value. Churches, in particular, are of high architectural and artistic value because they are built using various materials and construction techniques and may contain significant frescoes and mosaics. The knowledge of the state of foundations and ground material conditions is important for their proper restoration and preservation. Seismic tomography is employed to investigate the foundation structure and ground material of a Byzantine church. Energy sources are placed across the floor of the church and surrounding courts, while recorders are placed in a subterranean crypt. Travel time data are analyzed and processed with a three-dimensional (3D) tomographic inversion software in order to construct seismic velocity images at the foundation and below foundation level. Velocity variations are known to correlate well with the lithological character of the earth materials, thus providing important structural and lithological information. A case study from a Byzantine church of 11th c. A.D. in the suburbs of Athens, Greece, is presented. The objective of this research is the nondestructive investigation of unknown underground structures or void spaces, mainly under the floor of the building. The results are interpreted in terms of the foundation elements as well as of significant variations in the earth material character.

Investigating the seismic signal of elephants: using seismology to mitigate elephant human conflict

NASA Astrophysics Data System (ADS)

Webb, S. J.; Manzi, M.; Naidoo, A.; Raveloson, A.

2015-12-01

Human interactions with wild elephants are often a source of conflict, as elephants invade inhabited lands looking for sustenance. In order to mitigate these interactions, a number of elephant defense systems are under development. These include electric fences, bees and the playback of warning calls recorded from elephants. With the discovery that elephants use seismic signals to communicate (O'Connell-Rodwell et al., 2006, Behav. Ecol. Sociobiol.), it is hoped that seismic signals can also be used to help reduce conflict. Our current research project investigates the spectral content of the elephant seismic signal that travels through the ground using a variety of geophones and seismometers. Our experimental setup used a Geometrics Geode 24 channel seismic system with an array of 24 geophones spaced 1 m apart in an area of compact soil overlying weathered granites. Initially we used 14 Hz vertical geophones. The ground and ambient noise conditions were characterized by recording several hammer shots. These were used to identify the air wave, wind noise, and the direct wave, which had a dominant frequency of ~50 Hz. Several trained elephants that 'rumble' on command were then deployed ~5 m perpendicular to a line of 24 (14 Hz) vertical geophones between the 1 and 10 m geophone positions. We recorded a number of different elephants and configurations, and digitally recorded video for comparison. An additional deployment of 20 (14 Hz) horizontal geophones was also used. For all data, the sample interval was 0.25 ms and the recording length was 16 s as the timing of the rumbles could not be precisely controlled. We were able to identify the airwave due to the elephant's rumble with velocities between 305-310 m/s and the ground seismic signal due to the rumble with frequencies between 20-30 Hz. Our next experiment will include broadband seismometers at a further distance, to more fully characterize the frequency content of the elephant signal.

Polar Seismic TETwalker: Integrating Engineering Teaching and Research

NASA Astrophysics Data System (ADS)

Gifford, C. M.; Ruiz, I.; Carmichael, B. L.; Wade, U. B.; Agah, A.

2007-12-01

Based on the TETwalker robot platform at NASA/Goddard Space Flight Center, the Center for Remote Sensing of Ice Sheets (CReSIS) has begun work on designing and modeling the integration of seismic surveying equipment into the TETwalker robot architecture for use in polar environments. Employing multiple Seismic TETwalker robots will allow gathering of polar seismic data in previously inaccessible or unexplored terrains, as well as help significantly reduce human involvement in such harsh environments. NASA's TETwalker mobile robot uses a unique form of mobility to topple across the surface and over obstacles. This robot therefore does not suffer the fate of other wheeled and tracked robots if tipped over. It is composed of extending struts and nodes, forming a tetrahedral shape which can be strategically adjusted to change the robot's center of gravity for toppling. Of the many platforms the TETwalker architecture can form, the 4-TETwalker robot (consisting of four ground nodes, a center payload node, and interconnecting struts) has been the focus of current research. The center node has been chosen as the geophone deployment medium, designed in such a way to allow geophone insertion using any face of the robot's structure. As the robot comes to rest at the deployment location, one of its faces will rest on the surface. No matter which side it is resting on, a geophone spike will be perpendicular to its face and an extending strut will be vertical for pushing the geophone into the ground. Lengthening and shortening struts allow the deployment node to precisely place the geophone into the ground, as well as vertically orient the geophones for proper data acquisition on non-flat surfaces. Power source integration has been investigated, incorporating possible combinations of solar, wind, and vibration power devices onboard the robot models for long-term survival in a polar environment. Designs have also been modeled for an alternate center node sensor package (e

Investigations of Periodic Disturbances on Seismic Aftershock Recordings

NASA Astrophysics Data System (ADS)

Liebsch, Mattes; Gorschlüter, Felix; Knoop, Jan-Frederik; Altmann, Jürgen

2013-04-01

The Comprehensive Nuclear Test-Ban Treaty Organisation (CTBTO) runs the International Monitoring System (IMS) to detect possible violations of the treaty. The seismic sensors of the IMS are set up to detect every underground explosion with a yield of 1 kT TNT equivalent or even better everywhere on the world. Under consideration of all IMS data the hypocentre of a large underground explosion is located within an area of about 1000 sq km. To verify if it was a violation of the Test-Ban Treaty the CTBTO (after CTBT entry into force) is allowed to carry out an on-site inspection (OSI) in the area of suspicion. During an OSI the hypocentre is to be located much more precisely; for this a local seismic aftershock monitoring system (SAMS) can be installed to detect small seismic events caused as a consequence of the explosion, such as relaxation of the rock around the cavity. However the magnitude of these aftershock signals is extremely weak. Other difficulties arise from other seismic signals in the inspection area, for example caused by vehicles of the inspectors, from coupling of airborne signals to the ground, or even by intended attempts to disturb the OSI. While the aftershock signals have a pulsed shape, man-made seismic signals (primarily created by engines) usually show periodic characteristics and thus are representable as a sum of sine functions and their harmonics. A mathematical expression for the Hann-windowed discrete Fourier transform of the underlying sine is used to characterise every such disturbance by the amplitude, frequency and phase. The contributions of these sines are computed and subtracted from the complex spectrum sequentially. Synthetic sines superposed to real signals, orders of magnitude stronger than the latter, can be removed successfully. Removal of periodic content from the signals of a helicopter overflight reduces the amplitude by a factor 3.3 when the frequencies are approximately constant. To reduce or prevent disturbing seismic

Experimental Research on Seismic Performance of Four-Element Variable Cross-Sectional Concrete Filled Steel Tubular Laced Columns

NASA Astrophysics Data System (ADS)

Ou, Zhijing; Lin, Jianmao; Chen, Shengfu; Lin, Wen

2017-10-01

A total of 7 experimental tests were conducted to investigate seismic performance of four element variable cross-sectional Concrete Filled Steel Tubular (CFST) laced columns. The experimental parameters are longitudinal slope and arrangement type of lacing tubes. The rules on hysteresis loop, ductility, energy expenditure, and stiffness degradation of specimens are researched. Test results indicate that all specimens have good seismic performance; their hysteresis loops are full without obvious shrinkage. With the increase of longitudinal slope, the horizontal carrying capacity increases, energy dissipation capacity improve, and there is slightly increase in stiffness degradation. The influence of arrangement type of lacing tubes on displacement ductility of specimens is big.

Technology of research of hydroturbine unit work using seismic methods

NASA Astrophysics Data System (ADS)

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

2013-05-01

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

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

NASA Astrophysics Data System (ADS)

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.

Active and passive seismic investigations in Alpine Permafrost at Hoher Sonnblick (Austria)

NASA Astrophysics Data System (ADS)

Steiner, Matthias; Maierhofer, Theresa; Pfeiler, Stefan; Chwatal, Werner; Behm, Michael; Reisenhofer, Stefan; Schöner, Wolfgang; Straka, Wolfgang; Flores Orozco, Adrian

2017-04-01

Different geophysical measurements have been applied at the Hoher Sonnblick study area to gain information about permafrost distribution as well as heterogeneities controlling heat circulation, in the frame of the ÖAW-AtmoPerm project, which aims at the understanding the impacts of atmospheric extreme events on the thermal state of the active layer. Electrical Resistivity Tomography (ERT) has been widely accepted as a suitable method to characterize permafrost processes; however, limitations are imposed due to the challenges to inject high current densities in the frozen periods and the loss of resolution of electrical images at depth require the application of further geophysical methods. To overcome such problems, we investigate here the application of active and seismic methods. Seismic campaigns were performed using permanent borehole and temporarily installed surface geophones. A total of 15 borehole geophones are installed at depths of 1 m, 2 m, 5 m, 10 m and 20 m in three boreholes which are separated by a horizontal distance of 30 m between each other. Active measurements utilized 41 surface and 15 borehole geophones and a total of 199 excitation points. Surface geophones were laid out along two crossing lines with lengths of 92 m and 64 m, respectively. The longer line was placed directly along the borehole transect and the shorter one was oriented perpendicular to it. Hammer blows were performed with a spacing of 1 m inline the geophones and 4 m in crosslines rotated by 45 degrees, permitting 3D acquisition geometry. In addition to the active sources, data loggers connected to the borehole geophones permitted the collection of continuous 36-hours datasets for two different thermal conditions. Seismic ambient noise interferometry is applied to this data and aims at the identification of velocity changes in the subsurface related to seasonal changes of the active layer. A potential source of ambient seismic energy is the noise excited by hikers and the

Investigation of sinkhole areas in Germany using 2D shear wave reflection seismics and zero-offset VSP

NASA Astrophysics Data System (ADS)

Tschache, Saskia; Wadas, Sonja; Polom, Ulrich; Krawczyk, Charlotte M.

2017-04-01

Sinkholes pose a serious geohazard for humans and infrastructure in populated areas. The Junior Research Group Subrosion within the Leibniz Institute for Applied Geophysics and the joint project SIMULTAN work on the multi-scale investigation of subrosion processes in the subsurface, which cause natural sinkholes. In two case studies in sinkhole areas of Thuringia in Germany, we applied 2D shear wave reflection seismics using SH-waves with the aim to detect suitable parameters for the characterisation of critical zones. This method has the potential to image near-surface collapse and faulting structures in improved resolution compared to P-wave surveys resulting from the shorter wavelength of shear waves. Additionally, the shear wave velocity field derived by NMO velocity analysis is a basis to calculate further physical parameters, as e.g. the dynamic shear modulus. In both investigation areas, vertical seismic profiles (VSP) were acquired by generating P- and SH-waves (6 component VSP) directly next to a borehole equipped with a 3C downhole sensor. They provide shear and compressional wave velocity profiles, which are used to improve the 2D shear wave velocity field from surface seismics, to perform a depth calibration of the seismic image and to calculate the Vp/Vs ratio. The signals in the VSP data are analysed with respect to changes in polarisation and attenuation with depth and/or azimuth. The VSP data reveal low shear wave velocities of 200-300 m/s in rock layers known to be heavily affected by subrosion and confirm the low velocities calculated from the surface seismic data. A discrepancy of the shear wave velocities is observed in other intervals probably due to unsymmetrical travel paths in the surface seismics. In some VSP data dominant conversion of the direct SH-wave to P-wave is observed that is assumed to be caused by an increased presence of cavities. A potential fault distorting the vertical travel paths was detected by abnormal P-wave first

Microtremor survey to investigate seismic vulnerability around the Seulimum Fault, Aceh Besar-Indonesia

NASA Astrophysics Data System (ADS)

Simanjuntak, Andrean V. H.; Muksin, Umar; Rahmayani, Febrina

2018-05-01

The Seulimeum Fault has generated inland earthquake with magnitude larger than M 6.5 that destroyed houses in the Lamteuba and Krueng Raya Villages. Earthquakes along the Seulimeum Fault are mostly right lateral strike-slip characterizing the Fault. The understanding of the seismic vulnerability around the highly populated Banda Aceh City and the villages in Aceh Besar is therefore very important since the city, and the villages are very close to the Seulimeum Fault. A microtremor survey has been conducted to investigate seismic vulnerability in the area closed to the Seulimeum Fault. The waveforms of the microtremor have been recorded in Lamteuba and Kreung Raya villages, Aceh Besar at 20 sites for 7 days from August 14, 2017 with the interval of measurement of 1 km. The waveforms recorded for 30 minutes at each site by using one Taurus Seismometer in miniseed format. The data has been analyzing by using Geopsy to obtain the Horizontal-Vertical Spectral Ratio for each site. The seismic vulnerability is considered to be high if the value of the Horizontal-Vertical Spectral Ratio is high. The HVSR values are then interpolated to obtain the seismic vulnerability map. The preliminary result shows high seismic vulnerability in the area around the first site.

Investigating on the Differences between Triggered and Background Seismicity in Italy and Southern California.

NASA Astrophysics Data System (ADS)

Stallone, A.; Marzocchi, W.

2017-12-01

Earthquake occurrence may be approximated by a multidimensional Poisson clustering process, where each point of the Poisson process is replaced by a cluster of points, the latter corresponding to the well-known aftershock sequence (triggered events). Earthquake clusters and their parents are assumed to occur according to a Poisson process at a constant temporal rate proportional to the tectonic strain rate, while events within a cluster are modeled as generations of dependent events reproduced by a branching process. Although the occurrence of such space-time clusters is a general feature in different tectonic settings, seismic sequences seem to have marked differences from region to region: one example, among many others, is that seismic sequences of moderate magnitude in Italian Apennines seem to last longer than similar seismic sequences in California. In this work we investigate on the existence of possible differences in the earthquake clustering process in these two areas. At first, we separate the triggered and background components of seismicity in the Italian and Southern California seismic catalog. Then we study the space-time domain of the triggered earthquakes with the aim to identify possible variations in the triggering properties across the two regions. In the second part of the work we focus our attention on the characteristics of the background seismicity in both seismic catalogs. The assumption of time stationarity of the background seismicity (which includes both cluster parents and isolated events) is still under debate. Some authors suggest that the independent component of seismicity could undergo transient perturbations at various time scales due to different physical mechanisms, such as, for example, viscoelastic relaxation, presence of fluids, non-stationary plate motion, etc, whose impact may depend on the tectonic setting. Here we test if the background seismicity in the two regions can be satisfactorily described by the time

The Investigation of Active Tectonism Offshore Cide-Sinop, Southern Black Sea by Seismic Reflection and Bathymetric Data

NASA Astrophysics Data System (ADS)

Alp, Y. I.; Ocakoglu, N.; Kılıc, F.; Ozel, A. O.

2017-12-01

The active tectonism offshore Cide-Sinop at the Southern Black Sea shelf area was first time investigated by multi-beam bathymetric and multi-channel seismic reflection data under the Research Project of The Scientific and Technological Research Council of Turkey (TUBİTAK-ÇAYDAG-114Y057). The multi-channel seismic reflection data of about 700 km length were acquired in 1991 by Turkish Petroleum Company (TP). Multibeam bathymetric data were collected between 2002-2008 by the Turkish Navy, Department of Navigation, Hydrography and Oceanography (TN-DNHO). Conventional data processing steps were applied as follows: in-line geometry definition, shot-receiver static correction, editing, shot muting, gain correction, CDP sorting, velocity analysis, NMO correction, muting, stacking, predictive deconvolution, band-pass filtering, finite-difference time migration, and automatic gain correction. Offshore area is represented by a quite smooth and large shelf plain with an approx. 25 km wide and the water depth of about -100 m. The shelf gently deepens and it is limited by the shelf break with average of -120 m contour. The seafloor morphology is charasterised by an erosional surface. Structurally, E-W trending strike-slip faults with generally compression components and reverse/thrust faults have been regionally mapped for the first time. Most of these faults deform all seismic units and reach the seafloor delimiting the morphological highs and submarine plains. Thus, these faults are intepreted as active faults. These results support the idea that the area is under the active compressional tectonic regime

Investigation of the detection of shallow tunnels using electromagnetic and seismic waves

NASA Astrophysics Data System (ADS)

Counts, Tegan; Larson, Gregg; Gürbüz, Ali Cafer; McClellan, James H.; Scott, Waymond R., Jr.

2007-04-01

Multimodal detection of subsurface targets such as tunnels, pipes, reinforcement bars, and structures has been investigated using both ground-penetrating radar (GPR) and seismic sensors with signal processing techniques to enhance localization capabilities. Both systems have been tested in bi-static configurations but the GPR has been expanded to a multi-static configuration for improved performance. The use of two compatible sensors that sense different phenomena (GPR detects changes in electrical properties while the seismic system measures mechanical properties) increases the overall system's effectiveness in a wider range of soils and conditions. Two experimental scenarios have been investigated in a laboratory model with nearly homogeneous sand. Images formed from the raw data have been enhanced using beamforming inversion techniques and Hough Transform techniques to specifically address the detection of linear targets. The processed data clearly indicate the locations of the buried targets of various sizes at a range of depths.

Seismic site survey investigations in urban environments: The case of the underground metro project in Copenhagen, Denmark.

NASA Astrophysics Data System (ADS)

Martínez, K.; Mendoza, J. A.; Colberg-Larsen, J.; Ploug, C.

2009-05-01

Near surface geophysics applications are gaining more widespread use in geotechnical and engineering projects. The development of data acquisition, processing tools and interpretation methods have optimized survey time, reduced logistics costs and increase results reliability of seismic surveys during the last decades. However, the use of wide-scale geophysical methods under urban environments continues to face great challenges due to multiple noise sources and obstacles inherent to cities. A seismic pre-investigation was conducted to investigate the feasibility of using seismic methods to obtain information about the subsurface layer locations and media properties in Copenhagen. Such information is needed for hydrological, geotechnical and groundwater modeling related to the Cityringen underground metro project. The pre-investigation objectives were to validate methods in an urban environment and optimize field survey procedures, processing and interpretation methods in urban settings in the event of further seismic investigations. The geological setting at the survey site is characterized by several interlaced layers of clay, till and sand. These layers are found unevenly distributed throughout the city and present varying thickness, overlaying several different unit types of limestone at shallow depths. Specific results objectives were to map the bedrock surface, ascertain a structural geological framework and investigate bedrock media properties relevant to the construction design. The seismic test consisted of a combined seismic reflection and refraction analyses of a profile line conducted along an approximately 1400 m section in the northern part of Copenhagen, along the projected metro city line. The data acquisition was carried out using a 192 channels array, receiver groups with 5 m spacing and a Vibroseis as a source at 10 m spacing. Complementarily, six vertical seismic profiles (VSP) were performed at boreholes located along the line. The reflection

Seismic Methods

EPA Pesticide Factsheets

Seismic methods are the most commonly conducted geophysical surveys for engineering investigations. Seismic refraction provides engineers and geologists with the most basic of geologic data via simple procedures with common equipment.

Alternative Energy Sources in Seismic Methods

NASA Astrophysics Data System (ADS)

Tün, Muammer; Pekkan, Emrah; Mutlu, Sunay; Ecevitoğlu, Berkan

2015-04-01

When the suitability of a settlement area is investigated, soil-amplification, liquefaction and fault-related hazards should be defined, and the associated risks should be clarified. For this reason, soil engineering parameters and subsurface geological structure of a new settlement area should be investigated. Especially, faults covered with quaternary alluvium; thicknesses, shear-wave velocities and geometry of subsurface sediments could lead to a soil amplification during an earthquake. Likewise, changes in shear-wave velocities along the basin are also very important. Geophysical methods can be used to determine the local soil properties. In this study, use of alternative seismic energy sources when implementing seismic reflection, seismic refraction and MASW methods in the residential areas of Eskisehir/Turkey, were discussed. Our home developed seismic energy source, EAPSG (Electrically-Fired-PS-Gun), capable to shoot 2x24 magnum shotgun cartridges at once to generate P and S waves; and our home developed WD-500 (500 kg Weight Drop) seismic energy source, mounted on a truck, were developed under a scientific research project of Anadolu University. We were able to reach up to penetration depths of 1200 m for EAPSG, and 800 m for WD-500 in our seismic reflection surveys. WD-500 seismic energy source was also used to perform MASW surveys, using 24-channel, 10 m apart, 4.5 Hz vertical geophone configuration. We were able to reach 100 m of penetration depth in MASW surveys.

Opportunities for Undergraduates to Engage in Research Using Seismic Data and Data Products

NASA Astrophysics Data System (ADS)

Taber, J. J.; Hubenthal, M.; Benoit, M. H.

2014-12-01

Introductory Earth science classes can become more interactive through the use of a range of seismic data and models that are available online, which students can use to conduct simple research regarding earthquakes and earth structure. One way to introduce students to these data sets is via a new set of six intro-level classroom activities designed to introduce undergraduates to some of the grand challenges in seismology research. The activities all use real data sets and some require students to collect their own data, either using physical models or via Web sites and Web applications. While the activities are designed to step students through a learning sequence, several of the activities are open-ended and can be expanded to research topics. For example, collecting and analyzing data from a deceptively simple physical model of earthquake behavior can lead students to query a map-based seismicity catalog via the IRIS Earthquake Browser to study seismicity rates and the distribution of earthquake magnitudes, and make predictions about the earthquake hazards in regions of their choosing. In another activity, students can pose their own questions and reach conclusions regarding the correlation between hydraulic fracturing, waste water disposal, and earthquakes. Other data sources are available for students to engage in self-directed research projects. For students with an interest in instrumentation, they can conduct research relating to instrument calibration and sensitivity using a simple educational seismometer. More advanced students can explore tomographic models of seismic velocity structure, and examine research questions related to earth structure, such as the correlation of topography to crustal thickness, and the fate of subducted slabs. The type of faulting in a region can be explored using a map-based catalog of focal mechanisms, allowing students to analyze the spatial distribution of normal, thrust and strike-slip events in a subduction zone region

Field test investigation of high sensitivity fiber optic seismic geophone

NASA Astrophysics Data System (ADS)

Wang, Meng; Min, Li; Zhang, Xiaolei; Zhang, Faxiang; Sun, Zhihui; Li, Shujuan; Wang, Chang; Zhao, Zhong; Hao, Guanghu

2017-10-01

Seismic reflection, whose measured signal is the artificial seismic waves ,is the most effective method and widely used in the geophysical prospecting. And this method can be used for exploration of oil, gas and coal. When a seismic wave travelling through the Earth encounters an interface between two materials with different acoustic impedances, some of the wave energy will reflect off the interface and some will refract through the interface. At its most basic, the seismic reflection technique consists of generating seismic waves and measuring the time taken for the waves to travel from the source, reflect off an interface and be detected by an array of geophones at the surface. Compared to traditional geophones such as electric, magnetic, mechanical and gas geophone, optical fiber geophones have many advantages. Optical fiber geophones can achieve sensing and signal transmission simultaneously. With the development of fiber grating sensor technology, fiber bragg grating (FBG) is being applied in seismic exploration and draws more and more attention to its advantage of anti-electromagnetic interference, high sensitivity and insensitivity to meteorological conditions. In this paper, we designed a high sensitivity geophone and tested its sensitivity, based on the theory of FBG sensing. The frequency response range is from 10 Hz to 100 Hz and the acceleration of the fiber optic seismic geophone is over 1000pm/g. sixteen-element fiber optic seismic geophone array system is presented and the field test is performed in Shengli oilfield of China. The field test shows that: (1) the fiber optic seismic geophone has a higher sensitivity than the traditional geophone between 1-100 Hz;(2) The low frequency reflection wave continuity of fiber Bragg grating geophone is better.

Research on Seismic Wave Attenuation in Gas Hydrates Layer Using Vertical Cable Seismic Data

NASA Astrophysics Data System (ADS)

Wang, Xiangchun; Liang, Lunhang; Wu, Zhongliang

2018-06-01

Vertical cable seismic (VCS) data are the most suitable seismic data for estimating the quality factor Q values of layers under the sea bottom by now. Here the quality factor Q values are estimated using the high-precision logarithmic spectrum ratio method for VCS data. The estimated Q values are applied to identify the layers with gas hydrates and free gas. From the results it can be seen that the Q value in layer with gas hydrates becomes larger and the Q value in layer with free gas becomes smaller than layers without gas hydrates or free gas. Additionally, the estimated Q values are used for inverse Q filtering processing to compensate the attenuated seismic signal's high-frequency component. From the results it can be seen that the main frequency of seismic signal is improved and the frequency band is broadened, the resolution of the VCS data is improved effectively.

A seismic network to investigate the sedimentary hosted hydrothermal Lusi system

NASA Astrophysics Data System (ADS)

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.

GISMO: A MATLAB toolbox for seismic research, monitoring, & education

NASA Astrophysics Data System (ADS)

Thompson, G.; Reyes, C. G.; Kempler, L. A.

2017-12-01

GISMO is an open-source MATLAB toolbox which provides an object-oriented framework to build workflows and applications that read, process, visualize and write seismic waveform, catalog and instrument response data. GISMO can retrieve data from a variety of sources (e.g. FDSN web services, Earthworm/Winston servers) and data formats (SAC, Seisan, etc.). It can handle waveform data that crosses file boundaries. All this alleviates one of the most time consuming part for scientists developing their own codes. GISMO simplifies seismic data analysis by providing a common interface for your data, regardless of its source. Several common plots are built-in to GISMO, such as record section plots, spectrograms, depth-time sections, event count per unit time, energy release per unit time, etc. Other visualizations include map views and cross-sections of hypocentral data. Several common processing methods are also included, such as an extensive set of tools for correlation analysis. Support is being added to interface GISMO with ObsPy. GISMO encourages community development of an integrated set of codes and accompanying documentation, eliminating the need for seismologists to "reinvent the wheel". By sharing code the consistency and repeatability of results can be enhanced. GISMO is hosted on GitHub with documentation both within the source code and in the project wiki. GISMO has been used at the University of South Florida and University of Alaska Fairbanks in graduate-level courses including Seismic Data Analysis, Time Series Analysis and Computational Seismology. GISMO has also been tailored to interface with the common seismic monitoring software and data formats used by volcano observatories in the US and elsewhere. As an example, toolbox training was delivered to researchers at INETER (Nicaragua). Applications built on GISMO include IceWeb (e.g. web-based spectrograms), which has been used by Alaska Volcano Observatory since 1998 and became the prototype for the USGS

Preparing for InSight - using the continuous seismic data flow to investigate the deep interior of Mars

NASA Astrophysics Data System (ADS)

Hempel, S.; Garcia, R.; Weber, R. C.; Schmerr, N. C.; Panning, M. P.; Lognonne, P. H.; Banerdt, W. B.

2016-12-01

Complementary to investigating ray theoretically predictable parameters to explore the deep interior of Mars (see AGU contribution by R. Weber et al.), this paper presents the waveform approach to illuminate the lowermost mantle and core-mantle boundary of Mars. In preparation to the NASA discovery mission InSight, scheduled for launch in May, 2018, we produce synthetic waveforms considering realistic combinations of sources and a single receiver, as well as noise models. Due to a lack of constraints on the scattering properties of the Martian crust and mantle, we assume Earth-like scattering as a minimum and Moon-like scattering as a maximum possibility. Various seismic attenuation models are also investigated. InSight is set up to deliver event data as well as a continuous data flow. Where ray theoretical approaches will investigate the event data, the continuous data flow may contain signals reflected multiple times off the same reflector, e.g. the underside of the lithosphere, or the core-mantle boundary. It may also contain signals of individual events not detected or interfering wavefields radiated off multiple undetected events creating 'seismic noise'. We will use AxiSEM to simulate a continuous data flow for these cases for various 1D and 2D Mars models, and explore the possibilities of seismic interferometry to use seismic information hidden in the coda to investigate the deep interior of Mars.

Investigation of Seismic Waves from Non-Natural Sources: A Case Study for Building Collapse and Surface Explosion

NASA Astrophysics Data System (ADS)

Houng, S.; Hong, T.

2013-12-01

The nature and excitation mechanism of incidents or non-natural events have been widely investigated using seismological techniques. With introduction of dense seismic networks, small-sized non-natural events such as building collapse and chemical explosions are well recorded. Two representative non-natural seismic sources are investigated. A 5-story building in South Korea, Sampoong department store, was collapsed in June 25, 1995, causing casualty of 1445. This accident is known to be the second deadliest non-terror-related building collapse in the world. The event was well recorded by a local station in ~ 9 km away. P and S waves were recorded weak, while monotonic Rayleigh waves were observed well. The origin time is determined using surface-wave arrival time. The magnitude of event is determined to be 1.2, which coincides with a theoretical estimate based on the mass and volume of building. Synthetic waveforms are modeled for various combinations of velocity structures and source time functions, which allow us to constrain the process of building collapse. It appears that the building was collapsed once within a couple of seconds. We also investigate a M2.1 chemical explosion at a fertilizer plant in Texas on April 18, 2013. It was reported that more than one hundred people were dead or injured by the explosion. Seismic waveforms for nearby stations are collected from Incorporated Research Institution of Seismology (IRIS). The event was well recorded at stations in ~500 km away from the source. Strong acoustic signals were observed at stations in a certain great-circle direction. This observation suggests preferential propagation of acoustic waves depending on atmospheric environment. Waveform cross-correlation, spectral analysis and waveform modeling are applied to understand the source physics. We discuss the nature of source and source excitation mechanism.

Investigation of sea-level changes and shelf break prograding sequences during the Late Quaternary offshore of Kusadasi (West Anatolia) and surroundings by high resolution seismic methods

NASA Astrophysics Data System (ADS)

Gurcay, Savas; Cifci, Gunay; Dondurur, Derman; Okay, Seda; Atgin, Orhan; Ozel, Ozkan; Mert Kucuk, Hilmi

2016-04-01

High Resolution multi-channel seismic reflection and Chirp data were collected by K. Piri Reis, research vessel of Dokuz Eylül University, in the central Aegean coast of the West Anatolia by research cruises carried out in 2005 and 2008, respectively. Submarine stratigraphic and structural features of Sıǧacık Gulf, Kuşadası Gulf and surroundings were investigated under this survey. The data were processed and interpreted in SeisLab, D.E.U. Marine Sciences and Technology seismic laboratory. Thirteen distinct unconformities can be traced below the study area that separate thirteen progradational stacked paleo-delta sequences (Lob1-Lob13) on seismic profiles following and cutting each other. As a result of comparison with the oxygen isotopic stages (δ18), these deltas (Lob1-L13) were interpreted that they have been deposited during the sea-level lowstands within Pleistocene glacial stages. In the study area the basement surface which observed as the lowest unconformity surface of the seismic sections was called 'Acoustic Basement'. This basement which traced approximately all of the seismic sections has generally quite wavy surface and underlain the upper seismic units. It was observed that these seismic units which terminated their formation in Pleistocene (Lob1-Lob13) and Holocene period were cut and uplifted by acoustic basement, like an intrusion. These type deformations were interpreted as a result of magmatic intrusion into these upper seismic units occurred in Late Pleistocene and Holocene period. Tectonic and structural interpretation was carried out to constitute the submarine active tectonic map of the study area by correlated active faults identified on seismic sections. Submarine active tectonic map and, basement topography and sediment thickness map were correlated together to present the relationship between tectonic deformation and stratigraphy.

Investigation of seismicity after the initiation of a Seismic Electric Signal activity until the main shock

PubMed Central

Sarlis, N. V.; Skordas, E. S.; Lazaridou, M. S.; Varotsos, P. A.

2008-01-01

The behavior of seismicity in the area candidate to suffer a main shock is investigated after the observation of the Seismic Electric Signal activity until the impending main shock. This is based on the view that the occurrence of earthquakes is a critical phenomenon to which statistical dynamics may be applied. In the present work, analysing the time series of small earthquakes, the concept of natural time χ was used and the results revealed that the approach to criticality itself can be manifested by the probability density function (PDF) of κ1 calculated over an appropriate statistical ensemble. Here, κ1 is the variance κ1(= 〈χ2〉 − 〈χ〉2) resulting from the power spectrum of a function defined as Φ(ω)=∑k=1Npkexp(iωχk), where pk is the normalized energy of the k-th small earthquake and ω the natural frequency. This PDF exhibits a maximum at κ1 ≈ 0.070 a few days before the main shock. Examples are presented, referring to the magnitude 6∼7 class earthquakes that occurred in Greece. PMID:18941306

The Pollino Seismic Sequence: Activated Graben Structures in a Seismic Gap

NASA Astrophysics Data System (ADS)

Rößler, Dirk; Passarelli, Luigi; Govoni, Aladino; Bindi, Dino; Cesca, Simone; Hainzl, Sebatian; Maccaferri, Francesco; Rivalta, Eleonora; Woith, Heiko; Dahm, Torsten

2015-04-01

The Mercure Basin (MB) and the Castrovillari Fault (CF) in the Pollino range (Southern Apennines, Italy) represent one of the most prominent seismic gaps in the Italian seismic catalogue, with no M>5.5 earthquakes during the last centuries. In historical times several swarm-like seismic sequences occurred in the area including two intense swarms within the past two decades. The most energetic one started in 2010 and has been still active in 2014. The seismicity culminated in autumn 2012 with a M=5 event on 25 October. The range hosts a number of opposing normal faults forming a graben-like structure. Their rheology and their interactions are unclear. Current debates include the potential of the MB and the CF to host large earthquakes and the style of deformation. Understanding the seismicity and the behaviour of the faults is necessary to assess the tectonics and the seismic hazard. The GFZ German Research Centre for Geosciences and INGV, Italy, have jointly monitored the ongoing seismicity using a small-aperture seismic array, integrated in a temporary seismic network. Based on this installation, we located more than 16,000 local earthquakes that occurred between November 2012 and September 2014. Here we investigate quantitatively all the phases of the seismic sequence starting from January 2010. Event locations along with moment tensor inversion constrain spatially the structures activated by the swarm and the migration pattern of the seismicity. The seismicity forms clusters concentrated within the southern part of the MB and along the Pollino Fault linking MB and CF. Most earthquakes are confined to the upper 10 km of the crust in an area of ~15x15 km2. However, sparse seismicity at depths between 15 and 20 km and moderate seismicity further north with deepening hypocenters also exist. In contrast, the CF appears aseismic; only the northern part has experienced micro-seismicity. The spatial distribution is however more complex than the major tectonic structures

Seismic tomography as a tool for measuring stress in mines

USGS Publications Warehouse

Scott, Douglas F.; Williams, T.J.; Denton, D.K.; Friedel, M.J.

1999-01-01

Spokane Research Center personnel have been investigating the use of seismic tomography to monitor the behavior of a rock mass, detect hazardous ground conditions and assess the mechanical integrity of a rock mass affected by mining. Seismic tomography can be a valuable tool for determining relative stress in deep, >1,220-m (>4,000-ft), underground pillars. If high-stress areas are detected, they can be destressed prior to development or they can be avoided. High-stress areas can be monitored with successive seismic surveys to determine if stress decreases to a level where development can be initiated safely. There are several benefits to using seismic tomography to identify high stress in deep underground pillars. The technique is reliable, cost-effective, efficient and noninvasive. Also, investigators can monitor large rock masses, as well as monitor pillars during the mining cycle. By identifying areas of high stress, engineers will be able to assure that miners are working in a safer environment.Spokane Research Center personnel have been investigating the use of seismic tomography to monitor the behavior of a rock mass, detect hazardous ground conditions and assess the mechanical integrity of a rock mass affected by mining. Seismic tomography can be a valuable tool for determining relative stress in deep, >1,200-m (>4,000-ft), underground pillars. If high-stress areas are detected, they can be destressed prior to development or they can be avoided. High-stress areas can be monitored with successive seismic surveys to determine if stress decreases to a level where development can be initiated safely. There are several benefits to using seismic tomography to identify high stress in deep underground pillars. The technique is reliable, cost-effective, efficient and noninvasive. Also, investigators can monitor large rock masses, as well as monitor pillars during the mining cycle. By identifying areas of high stress. engineers will be able to assure that miners are

High-frequency seismic noise: Results of investigation in Kamchatka

NASA Astrophysics Data System (ADS)

Saltykov, V.; Chebrov, V.; Kugaenko, Yu.; Sinitsyn, V.

The investigation of seismic noise in Kamchatka is carried out for the control of the medium stress condition and search of the strong earthquakes precursors. The main directions of this research are modulation of high-frequency seismic noise (HFSN, frequency range of the first tens of Hz, amplitudes about 10 -9-10 -12 m) by the Earth tides and temporal variations of HFSN parameters connected with the strong earthquake preparation. For reception of the statistically significant characteristics of HFSN and tides connection it was necessary to carry out long-term HFSN observations in points free from anthropogenous influence as far as possible. The station of HFSN observation was organized in the settlement Nachiky. The sensor is a narrow-band ( Q = 100) piezoelectric seismometer, tuned to frequency 30 Hz. Signal envelope is recorded and analyzed. The continuous HFSN registration was begun in 1990 and proceeds till now. In 2000 the second station was established in the complex geophysical observatory “Karymshina”. The HFSN sensor is set up in the borehole at the depth of 30 m. The research of HFSN structure gave the opportunity to allocate HFSN components connected with the Earth tides. Besides it was revealed that the tidal response is not stable in time: the intervals of the tidal component existence are replaced by intervals of its absence, correlation between tide and HFSN varies in time, while tides have constant parameters. We propose a hypothesis about the connection of variations of the tidal components in HFSN data with the tectonic conditions in region, and consequently, about an opportunity to use this phenomenon for the prediction of strong earthquakes. The phase of the HFSN component connected with a tidal wave O1 ( T = 25.8 h) was chosen as a parameter. The choice of wave O1 is connected with its greatest hindrance-immunity. It was shown that the stabilization of this phase is observed before earthquakes with M > 6.0, occurred at distances up to 250

Reevaluation of the Seismicity and seismic hazards of Northeastern Libya

NASA Astrophysics Data System (ADS)

Ben Suleman, abdunnur; Aousetta, Fawzi

2014-05-01

Libya, located at the northern margin of the African continent, underwent many episodes of orogenic activities. These episodes of orogenic activities affected and shaped the geological setting of the country. This study represents a detailed investigation that aims to focus on the seismicity and its implications on earthquake hazards of Northeastern Libya. At the end of year 2005 the Libyan National Seismological Network starts functioning with 15 stations. The Seismicity of the area under investigation was reevaluated using data recorded by the recently established network. The Al-Maraj earthquake occurred in May 22nd 2005was analyzed. This earthquake was located in a known seismically active area. This area was the sight of the well known 1963 earthquake that kills over 200 people. Earthquakes were plotted and resulting maps were interpreted and discussed. The level of seismic activity is higher in some areas, such as the city of Al-Maraj. The offshore areas north of Al-Maraj seem to have higher seismic activity. It is highly recommended that the recent earthquake activity is considered in the seismic hazard assessments for the northeastern part of Libya.

Seismic Reflection Methods

EPA Pesticide Factsheets

Seismic methods are the most commonly conducted geophysical surveys for engineering investigations. Seismic refraction provides engineers and geologists with the most basic of geologic data via simple procedures with common equipment.

Gravity and Seismic Investigations of the Northern Rio Grande Rift Area, New Mexico

NASA Astrophysics Data System (ADS)

Braile, L. W.; Deepak, A.; Helprin, O.; Kondas, S.; Maguire, H.; McCallister, B.; Orubu, A.; Rijfkogel, L.; Schumann, H.; Vannette, M.; Wanpiyarat, N.; Carchedi, C.; Ferguson, J. F.; McPhee, D.; Biehler, S.; Ralston, M. D.; Baldridge, W. S.

2017-12-01

Participants in the Summer of Applied Geophysical Experience (SAGE, a research and education program in applied geophysics for undergraduate and graduate students) program have studied the northern Rio Grande rift (RGR) area of New Mexico for the past thirty-five years. In recent years, the SAGE program has focused on the western edge of the Española basin and the transition into the Santo Domingo basin and the Valles caldera. During this time, we have collected about 50 km of seismic reflection and refraction data along approximately East-West profiles using a 120 channel data acquisition system with a 20 m station interval and a Vibroseis source. We also have access to several energy-industry seismic reflection record sections from the 1970s in the study area. During SAGE 2017, new gravity measurements north of the Jemez Mountains and a seismic reflection profile (Rio de Truchas Profile) in the Valarde graben adjacent to the eastern boundary of the RGR have added new constraints to a west-to-east transect in area of the northern RGR. The recorded near-vertical and wide-angle seismic refection data were processed to produce a CMP (common midpoint) stacked record section. Bandpass filtering, muting, deconvolution, and F-K velocity filtering were found to be effective in enhancing the seismic reflections. Modeling and interpretation of the northern RGR west-to-east geophysical profile indicates that the sedimentary rock fill in the Velarde graben is at least 3 km near the center of the graben. Gravity modeling also suggests the presence of a high-density intrusion at the top of the crystalline basement in an area to the north and west of Abiquiu, NM.

The Virtual Seismic Atlas Project: sharing the interpretation of seismic data

NASA Astrophysics Data System (ADS)

Butler, R.; Mortimer, E.; McCaffrey, B.; Stuart, G.; Sizer, M.; Clayton, S.

2007-12-01

Through the activities of academic research programs, national institutions and corporations, especially oil and gas companies, there is a substantial volume of seismic reflection data. Although the majority is proprietary and confidential, there are significant volumes of data that are potentially within the public domain and available for research. Yet the community is poorly connected to these data and consequently geological and other research using seismic reflection data is limited to very few groups of researchers. This is about to change. The Virtual Seismic Atlas (VSA) is generating an independent, free-to-use, community based internet resource that captures and shares the geological interpretation of seismic data globally. Images and associated documents are explicitly indexed using not only existing survey and geographical data but also on the geology they portray. By using "Guided Navigation" to search, discover and retrieve images, users are exposed to arrays of geological analogues that provide novel insights and opportunities for research and education. The VSA goes live, with evolving content and functionality, through 2008. There are opportunities for designed integration with other global data programs in the earth sciences.

Research on seismic behavior and filling effect of a new CFT column-CFT beam frame structure

NASA Astrophysics Data System (ADS)

Wang, Ying; Shima, Hiroshi

2009-12-01

Concrete filled-steel tube (CFT) structure is popularly used in practical structures nowadays. Self-compacting concrete (SCC) was employed to construct a new CFT column-CFT beam frame structure (hereinafter cited as new CFT frame structure) in this research. Three specimens, two CFT column-CFT beam joints and one hollow steel column-I beam joint were tested to investigate seismic behavior of the new CFT frame structure. The experimental results showed that SCC can be successfully compacted into the new CFT frame structure joints in the lab, and the joints provided adequate seismic behavior. In order to further assess filling effect of SCC in the long steel tube, scale column-beam subassembly made of acrylics plate was employed and concrete visual model experiment was done. The results showed that the concrete was able to be successfully cast into the subassembly which indicated that the new CFT frame structure is possible to be constructed in the real building.

Research on seismic behavior and filling effect of a new CFT column-CFT beam frame structure

NASA Astrophysics Data System (ADS)

Wang, Ying; Shima, Hiroshi

2010-03-01

Concrete filled-steel tube (CFT) structure is popularly used in practical structures nowadays. Self-compacting concrete (SCC) was employed to construct a new CFT column-CFT beam frame structure (hereinafter cited as new CFT frame structure) in this research. Three specimens, two CFT column-CFT beam joints and one hollow steel column-I beam joint were tested to investigate seismic behavior of the new CFT frame structure. The experimental results showed that SCC can be successfully compacted into the new CFT frame structure joints in the lab, and the joints provided adequate seismic behavior. In order to further assess filling effect of SCC in the long steel tube, scale column-beam subassembly made of acrylics plate was employed and concrete visual model experiment was done. The results showed that the concrete was able to be successfully cast into the subassembly which indicated that the new CFT frame structure is possible to be constructed in the real building.

Sensing network for electromagnetic fields generated by seismic activities

NASA Astrophysics Data System (ADS)

Gershenzon, Naum I.; Bambakidis, Gust; Ternovskiy, Igor V.

2014-06-01

The sensors network is becoming prolific and play now increasingly more important role in acquiring and processing information. Cyber-Physical Systems are focusing on investigation of integrated systems that includes sensing, networking, and computations. The physics of the seismic measurement and electromagnetic field measurement requires special consideration how to design electromagnetic field measurement networks for both research and detection earthquakes and explosions along with the seismic measurement networks. In addition, the electromagnetic sensor network itself could be designed and deployed, as a research tool with great deal of flexibility, the placement of the measuring nodes must be design based on systematic analysis of the seismic-electromagnetic interaction. In this article, we review the observations of the co-seismic electromagnetic field generated by earthquakes and man-made sources such as vibrations and explosions. The theoretical investigation allows the distribution of sensor nodes to be optimized and could be used to support existing geological networks. The placement of sensor nodes have to be determined based on physics of electromagnetic field distribution above the ground level. The results of theoretical investigations of seismo-electromagnetic phenomena are considered in Section I. First, we compare the relative contribution of various types of mechano-electromagnetic mechanisms and then analyze in detail the calculation of electromagnetic fields generated by piezomagnetic and electrokinetic effects.

Stochastic Seismic Inversion and Migration for Offshore Site Investigation in the Northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Son, J.; Medina-Cetina, Z.

2017-12-01

We discuss the comparison between deterministic and stochastic optimization approaches to the nonlinear geophysical full-waveform inverse problem, based on the seismic survey data from Mississippi Canyon in the Northern Gulf of Mexico. Since the subsea engineering and offshore construction projects actively require reliable ground models from various site investigations, the primary goal of this study is to reconstruct the accurate subsurface information of the soil and rock material profiles under the seafloor. The shallow sediment layers have naturally formed heterogeneous formations which may cause unwanted marine landslides or foundation failures of underwater infrastructure. We chose the quasi-Newton and simulated annealing as deterministic and stochastic optimization algorithms respectively. Seismic forward modeling based on finite difference method with absorbing boundary condition implements the iterative simulations in the inverse modeling. We briefly report on numerical experiments using a synthetic data as an offshore ground model which contains shallow artificial target profiles of geomaterials under the seafloor. We apply the seismic migration processing and generate Voronoi tessellation on two-dimensional space-domain to improve the computational efficiency of the imaging stratigraphical velocity model reconstruction. We then report on the detail of a field data implementation, which shows the complex geologic structures in the Northern Gulf of Mexico. Lastly, we compare the new inverted image of subsurface site profiles in the space-domain with the previously processed seismic image in the time-domain at the same location. Overall, stochastic optimization for seismic inversion with migration and Voronoi tessellation show significant promise to improve the subsurface imaging of ground models and improve the computational efficiency required for the full waveform inversion. We anticipate that by improving the inversion process of shallow layers from

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

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

Applying the seismic interferometry method to vertical seismic profile data using tunnel excavation noise as source

NASA Astrophysics Data System (ADS)

Jurado, Maria Jose; Teixido, Teresa; Martin, Elena; Segarra, Miguel; Segura, Carlos

2013-04-01

In the frame of the research conducted to develop efficient strategies for investigation of rock properties and fluids ahead of tunnel excavations the seismic interferometry method was applied to analyze the data acquired in boreholes instrumented with geophone strings. The results obtained confirmed that seismic interferometry provided an improved resolution of petrophysical properties to identify heterogeneities and geological structures ahead of the excavation. These features are beyond the resolution of other conventional geophysical methods but can be the cause severe problems in the excavation of tunnels. Geophone strings were used to record different types of seismic noise generated at the tunnel head during excavation with a tunnelling machine and also during the placement of the rings covering the tunnel excavation. In this study we show how tunnel construction activities have been characterized as source of seismic signal and used in our research as the seismic source signal for generating a 3D reflection seismic survey. The data was recorded in vertical water filled borehole with a borehole seismic string at a distance of 60 m from the tunnel trace. A reference pilot signal was obtained from seismograms acquired close the tunnel face excavation in order to obtain best signal-to-noise ratio to be used in the interferometry processing (Poletto et al., 2010). The seismic interferometry method (Claerbout 1968) was successfully applied to image the subsurface geological structure using the seismic wave field generated by tunneling (tunnelling machine and construction activities) recorded with geophone strings. This technique was applied simulating virtual shot records related to the number of receivers in the borehole with the seismic transmitted events, and processing the data as a reflection seismic survey. The pseudo reflective wave field was obtained by cross-correlation of the transmitted wave data. We applied the relationship between the transmission

Man-caused seismicity of Kuzbass

NASA Astrophysics Data System (ADS)

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

2010-05-01

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

High-resolution reflection seismic survey at a CCS site, Taiwan

NASA Astrophysics Data System (ADS)

Wang, Chien-Ying; Chung, Chen-Tung; Kuo, Hsuan-Yu; Wu, Ming-shyan; Kuo-Chen, Hao

2017-04-01

To control the effect of greenhouse gas on global warming, the reduction of carbon dioxide emission has become a significant international issue in recent years. The capture of carbon dioxide during its manufacturing and storing in adjacent areas are the most economical way. This research uses high-resolution seismic reflection survey to investigate the region around the world's largest coal-fired power plant at Taichung Port, Taiwan. We aim to detect proper geological structures and to evaluate the possible way to store carbon dioxide. This research uses reflection seismic survey with two mini-vibrators and 240 channels to investigate detailed underground structures. The total length of seismic lines is more than 20 kilometers. By aligning sequential seismic lines, we are able to correlate stratigraphic layers over a wide area. Two adjacent wells along the seismic line are used to identified possible formations. The TaiChung Power Plant (TCPP) at Taichung Port is our target which has more cross-tied seismic lines and a seismic line even extending into the sea water. We analyze these seismic profiles to establish the geological model for carbon dioxide storage and evaluate the possibility of storage systems. Furthermore, this research may prepare some baseline data for the future carbon dioxide injection monitoring. The result shows that the geological structures striking 8 degrees east of north and dipping 2.8 degrees to the east. This means that carbon dioxide will migrate toward the sea direction after injection. The structural layers are relatively flat without any sign of faults. Three carbon dioxide storage systems : Mushan Wuchihshan—Paling(bottom), Peiliao—Talu(middle) and Kueichulin—Chinshui(upper) system are identified. All has the proper reservoir with high porosity and capable caprocks more than 100 meters thick. The geological storage of carbon dioxide injected into TCPP site is a feasible, commercial and safe way to reduce the emission of carbon

Wide-angle seismic recordings from the 1998 Seismic Hazards Investigation of Puget Sound (SHIPS), western Washington and British Columbia

USGS Publications Warehouse

Brocher, Thomas M.; Parsons, Tom; Creager, Ken C.; Crosson, Robert S.; Symons, Neill P.; Spence, George D.; Zelt, Barry C.; Hammer, Philip T.C.; Hyndman, Roy D.; Mosher, David C.; Tréhu, Anne M.; Miller, Kate C.; ten Brink, Uri S.; Fisher, Michael A.; Pratt, Thomas L.; Alvarez, Marcos G.; Beaudoin, Bruce C.; Louden, Keith E.; Weaver, Craig S.

1999-01-01

This report describes the acquisition and processing of deep-crustal wide-angle seismic reflection and refraction data obtained in the vicinity of Puget Lowland, the Strait of Juan de Fuca, and Georgia Strait, western Washington and southwestern British Columbia, in March 1998 during the Seismic Hazards Investigation of Puget Sound (SHIPS). As part of a larger initiative to better understand lateral variations in crustal structure along the Cascadia margin, SHIPS participants acquired 1000 km of deep-crustal multichannel seismic-reflection profiles and 1300 km of wideangle airgun shot lines in this region using the R/V Thompson and R/V Tully. The Tully was used to record airgun shots fired by the Thompson in two different geometries: (1) expanding spread profiles (ESPs) and (2) constant offset profiles (COPs). Prior to this reflection survey, we deployed 257 Reftek and 15 ocean-bottom seismic recorders to record the airgun signals at far offsets. All data were recorded digitally on large-capacity hard disks. Although most of these stations only recorded the vertical component of motion, 95 of these seismographs recorded signals from an oriented 3-component seismometer. By recording signals generated by the Thompson's marine air gun array, operated in two differing geometries having a total volume of 110 and 79 liters (6730 and 4838 cu. in.), respectively, the arrays of wide-angle recorders were designed to (1) image the crustal structure, particularly in the vicinity of crustal faults and Cenozoic sedimentary basins, (2) determine the geometry of the Moho, and (3) image the subducting Gorda and Juan de Fuca plates. Nearly 33,300 air gun shots were recorded along several seismic lines. In this report, we illustrate the expanding spread profiles acquired using the Thompson and Tully, describe the land and ocean-bottom recording of the air gun signals, discuss the processing of the land recorder data into common receiver gathers, and illustrate the processed wide

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

NASA Astrophysics Data System (ADS)

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.

Earthquake recordings from the 2002 Seattle Seismic Hazard Investigation of Puget Sound (SHIPS), Washington State

USGS Publications Warehouse

Pratt, Thomas L.; Meagher, Karen L.; Brocher, Thomas M.; Yelin, Thomas; Norris, Robert; Hultgrien, Lynn; Barnett, Elizabeth; Weaver, Craig S.

2003-01-01

This report describes seismic data obtained during the fourth Seismic Hazard Investigation of Puget Sound (SHIPS) experiment, termed Seattle SHIPS . The experiment was designed to study the influence of the Seattle sedimentary basin on ground shaking during earthquakes. To accomplish this, we deployed seismometers over the basin to record local earthquakes, quarry blasts, and teleseisms during the period of January 26 to May 27, 2002. We plan to analyze the recordings to compute spectral amplitudes at each site, to determine the variability of ground motions over the basin. During the Seattle SHIPS experiment, seismometers were deployed at 87 sites in a 110-km-long east-west line, three north-south lines, and a grid throughout the Seattle urban area (Figure 1). At each of these sites, an L-22, 2-Hz velocity transducer was installed and connected to a REF TEK Digital Acquisition System (DAS), both provided by the Program for Array Seismic Studies of the Continental Lithosphere (PASSCAL) of the Incorporated Research Institutes for Seismology (IRIS). The instruments were installed on January 26 and 27, and were retrieved gradually between April 18 and May 27. All instruments continuously sampled all three components of motion (velocity) at a sample rate of 50 samples/sec. To ensure accurate computations of amplitude, we calibrated the geophones in situ to obtain the instrument responses. In this report, we discuss the acquisition of these data, we describe the processing and merging of these data into 1-hour long traces and into windowed events, we discuss the geophone calibration process and its results, and we display some of the earthquake recordings.

A new event detector designed for the Seismic Research Observatories

USGS Publications Warehouse

Murdock, James N.; Hutt, Charles R.

1983-01-01

A new short-period event detector has been implemented on the Seismic Research Observatories. For each signal detected, a printed output gives estimates of the time of onset of the signal, direction of the first break, quality of onset, period and maximum amplitude of the signal, and an estimate of the variability of the background noise. On the SRO system, the new algorithm runs ~2.5x faster than the former (power level) detector. This increase in speed is due to the design of the algorithm: all operations can be performed by simple shifts, additions, and comparisons (floating point operations are not required). Even though a narrow-band recursive filter is not used, the algorithm appears to detect events competitively with those algorithms that employ such filters. Tests at Albuquerque Seismological Laboratory on data supplied by Blandford suggest performance commensurate with the on-line detector of the Seismic Data Analysis Center, Alexandria, Virginia.

Structural Identification And Seismic Analysis Of An Existing Masonry Building

DOE Office of Scientific and Technical Information (OSTI.GOV)

Del Monte, Emanuele; Galano, Luciano; Ortolani, Barbara

2008-07-08

The paper presents the diagnostic investigation and the seismic analysis performed on an ancient masonry building in Florence. The building has historical interest and is subjected to conservative restrictions. The investigation involves a preliminary phase concerning the research of the historic documents and a second phase of execution of in situ and laboratory tests to detect the mechanical characteristics of the masonry. This investigation was conceived in order to obtain the 'LC2 Knowledge Level' and to perform the non-linear pushover analysis according to the new Italian Standards for seismic upgrading of existing masonry buildings.

Combined seismic and radar investigation to define ice properties and structure of a cold alpine site

NASA Astrophysics Data System (ADS)

Eisen, O.; Bohleber, P.; Drews, R.; Heilig, A.; Hofstede, C.

2009-04-01

The cold alpine saddle Colle Gnifetti, Monte Rosa, Swiss-Italian Alps resembles very much polar and subpolar ice masses in terms of glaciological conditions. It has been the site for several ice-core drilling campaigns over more than 20 years to determine paleoclimatological and glaciological conditions. To investigate the feasibility of geophysical methods for improved characterization of ice masses surrounding borehole and ice-core sites, a combined active reflection seismic and ground-penetrating radar pilot study has been carried out in summer 2008. Aims are the characterization of density, internal layering, seismic and radar wave speed and attenuation, identification of anisotropic features (like crystal orientation or bubble content and shape). Here we present the overall setup and first results. Seismic and GPR profiles were centered on an existing borehole location covering the full ice thickness of 62 m. Active seismics was carried out with 24-channel 3-m spacing recording, using a Seismic Impulse Source System (SISSY) along two profiles parallel and perpendicular to the ice-flow direction. The same profiles were complemented with GPR measurements utilizing 250, 500 MHz frequencies. Additionally, circular profiles with 250, 500 and 800 MHz were carried out circumferencing the borehole to detect anisotropic features.

Geomorphology and seismic risk

NASA Astrophysics Data System (ADS)

Panizza, Mario

1991-07-01

The author analyses the contributions provided by geomorphology in studies suited to the assessment of seismic risk: this is defined as function of the seismic hazard, of the seismic susceptibility, and of the vulnerability. The geomorphological studies applicable to seismic risk assessment can be divided into two sectors: (a) morpho-neotectonic investigations conducted to identify active tectonic structures; (b) geomorphological and morphometric analyses aimed at identifying the particular situations that amplify or reduce seismic susceptibility. The morpho-neotectonic studies lead to the identification, selection and classification of the lineaments that can be linked with active tectonic structures. The most important geomorphological situations that can condition seismic susceptibility are: slope angle, debris, morphology, degradational slopes, paleo-landslides and underground cavities.

Seismic performance of non-structural components and contents in buildings: an overview of NZ research

NASA Astrophysics Data System (ADS)

Dhakal, Rajesh P.; Pourali, Atefeh; Tasligedik, Ali Sahin; Yeow, Trevor; Baird, Andrew; MacRae, Gregory; Pampanin, Stefano; Palermo, Alessandro

2016-03-01

This paper summarizes the research on non-structural elements and building contents being conducted at University of Canterbury in New Zealand. Since the 2010-2011 series of Canterbury earthquakes, in which damage to non-structural components and contents contributed heavily to downtime and overall financial loss, attention to seismic performance and design of non-structural components and contents in buildings has increased exponentially in NZ. This has resulted in an increased allocation of resources to research leading to development of more resilient non-structural systems in buildings that would incur substantially less damage and cause little downtime during earthquakes. In the last few years, NZ researchers have made important developments in understanding and improving the seismic performance of secondary building elements such as partitions, facades, ceilings and contents.

Seismic Investigation of Magmatic Unrest Beneath Mammoth Mountain, California Using Waveform Cross-Correlation

NASA Astrophysics Data System (ADS)

Lin, G.

2012-12-01

We investigate the seismic and magmatic activity during an 11-month-long seismic swarm between 1989 and 1990 beneath Mammoth Mountain (MM) at the southwest rim of Long Valley caldera in eastern California. This swarm is believed to be results of a shallow intrusion of magma beneath MM. It was followed by the emissions of carbon dioxide (CO2) gas, which caused tree-killings in 1990 and posed a significant human health risk around MM. In this study, we develop a new three-dimensional (3-D) P-wave velocity model using first-arrival picks by applying the simul2000 tomographic algorithm. The resulting 3-D model is correlated with the surface geological features at shallow depths and is used to constrain absolute earthquake locations for all local events in our study. We compute both P- and S-wave differential times using a time-domain waveform cross-correlation method. We then apply similar event cluster analysis and differential time location approach to further improve relative event location accuracy. A dramatic sharpening of seismicity pattern is obtained after these processes. The estimated uncertainties are a few meters in relative location and ~100 meters in absolute location. We also apply a high-resolution approach to estimate in situ near-source Vp/Vs ratios using differential times from waveform cross-correlation. This method provides highly precise results because cross-correlation can measure differential times to within a few milliseconds and can achieve a precision of 0.001 in estimated Vp/Vs ratio. Our results show a circular ring-like seismicity pattern with a diameter of 2 km between 3 and 8 km depth. These events are distributed in an anomalous body with low Vp and high Vp/Vs, which may be caused by over-pressured magmatically derived fluids. At shallower depths, we observe very low Vp/Vs anomalies beneath MM from the surface to 1 km below sea level whose locations agree with the proposed CO2 reservoir in previous studies. The systematic spatial and

Investigating the Effects Fracture Systems Have on Seismic Wave Velocities at the Lajitas, Texas Seismic Station

DTIC Science & Technology

1989-05-01

Victoria L. Sandidge-Bodoh % S Southern Methodist University Department of Geological Sciences Dallas, TX 75275 1 May 1989 Final Report 3 March 1987 - 2...Projects Agency or the U.S. Government. This technical report has been reviewed and is approved for publicj ion. JAME F. LEWKOW(CZ J/ S F. LEWKOWiC...Effects Fracture Systems Have on Seismic Wave Velocities at the Lajitas, Texas Seismic Station 12. PERSONAL AUTHOR( S ) Victoria L. Sandidge-Bodoh 13a. TYPE

Investigation Of North Anatolian Fault In The Sea Of Marmara: Fault Geometry, The Cumulative Extension, Age Modeling In Çinarcik Basin Using Multi Channel Seismic Reflection Data

NASA Astrophysics Data System (ADS)

Atgın, Orhan; Çifçi, Günay; Soelien, Christopher; Seeber, Leonardo; Steckler, Michael; Shillington, Donna; Kurt, Hülya; Dondurur, Derman; Okay, Seda; Gürçay, Savaş; Sarıtaş, Hakan; Mert Küçük, H.; Barın, Burcu

2013-04-01

Marmara Sea is a limelight area for investigations due to its tectonic structure and remarkable seismic activity of North Anatolian Fault Zone (NAFZ). As NAFZ separates into 3 branches in the Marmara Sea, it has a complicated tectonic structure which gives rise to debates among researchers. Çınarcık Basin, which is close to Istanbul and very important for its tectonic activity is studied in this thesis. Two different multichannel seismic reflection data were used in this thesis. First data were acquired in 2008 in the frame of TAMAM (Turkish American Multichannel Project) and second data were in 2010 in the frame of TAMAM-2 (PirMarmara) onboard R/V K.Piri Reis. Also high resolution multibeam data were used which is provided by French Marine Institute IFREMER. In the scope of TAMAM project total 3000 km high resolution multi channel data were collected. 3000 km of multichannel seismic reflection profiles were collected in 2008 and 2010 using 72, 111, and 240 channels of streamer with a 6.25 m group interval. The generator-injector airgun was fired every 12.5 or 18.75 m and the resulting MCS data has 10-230 Hz frequency band. In this study, a detailed fault map of the basin is created and the fault on the southern slope of the basin which is interpreted by many researchers in many publications was investigated. And there is no evidence that such a fault exists on the southern part of the basin. With the multichannel seismic reflection data seismic stratigrafic interpretations of the basin deposits were done. The yearly cumulative north-south extension of the basin was calculated by making some calculations on the most active part of the faulting in the basin. In addition, the tilt angles of parallel tilted sediments were calculated and correlated with global sea level changes to calculate ages of the deposits in the basin. Keywords: NAFZ, multi channel seismic reflection, Çınarcık Basin

Seismic risk perception in Italy

NASA Astrophysics Data System (ADS)

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

2014-05-01

Risk perception is a fundamental element in the definition and the adoption of preventive counter-measures. In order to develop effective information and risk communication strategies, the perception of risks and the influencing factors should be known. This paper presents results of a survey on seismic risk perception in Italy conducted from January 2013 to present . The research design combines a psychometric and a cultural theoretic approach. More than 7,000 on-line tests have been compiled. The data collected show that in Italy seismic risk perception is strongly underestimated; 86 on 100 Italian citizens, living in the most dangerous zone (namely Zone 1), do not have a correct perception of seismic hazard. From these observations we deem that extremely urgent measures are required in Italy to reach an effective way to communicate seismic risk. Finally, the research presents a comparison between groups on seismic risk perception: a group involved in campaigns of information and education on seismic risk and a control group.

Reprocessing Seismic Data - Using Wits Seismic Exploration Data to Image the Karoo Basin

NASA Astrophysics Data System (ADS)

Webb, S. J.; Scheiber-Enslin, S. E.; Manzi, M. S.

2016-12-01

During the heyday of seismic exploration of the Witwatersrand Basin, Anglo American's Gold Division acquired several thousand kilometres of Vibroseis reflection seismic data. These data, acquired from 1983-1994, were collected with the goal of finding extensions to the Witwatersrand Basin. In a prescient move, over 500 line kilometres were collected at 16 s two way travel time (TWT), extending to depths of 50 -70 km and have provided critical insight into the formation of the Kaapvaal Craton. In addition to these deep seismic lines, Anglo American acquired an extensive network of heretofore unpublished seismic lines that were collected at 6 sec TWT extending well beyond the known limits of the Witwatersrand Basin. The South African government as part of the national geophysical program in the late 1980s acquired six research reflection seismic lines in varied geological settings accruing another 700 km of data. Many of these data are now hosted at the University of the Witwatersrand's newly established Seismic Research Centre and represent unprecedented coverage and research opportunities. With recent global interest in shale gas, attention focused on the Karoo Basin in South Africa. Early exploration seismic data acquired by Soekor in the 1970s has been lost; however, digitized paper records indicate clear reflection targets. Here we examine one of the AngloGold seismic lines that was acquired in the middle of the Karoo Basin just south of Trompsburg extending to the southeast towards Molteno. This 150 km long line crosses the edge of the Kaapvaal Craton and shows clear reflectors throughout the Karoo Basin. These include the well-defined base of the Karoo and a number of dolerite sills within it. Nearby gas escape structures have been identified on surface and it is likely that several disruptions along this line are related to these or to dykes associated with the sills.

3D Modelling of Seismically Active Parts of Underground Faults via Seismic Data Mining

NASA Astrophysics Data System (ADS)

Frantzeskakis, Theofanis; Konstantaras, Anthony

2015-04-01

During the last few years rapid steps have been taken towards drilling for oil in the western Mediterranean sea. Since most of the countries in the region benefit mainly from tourism and considering that the Mediterranean is a closed sea only replenishing its water once every ninety years careful measures are being taken to ensure safe drilling. In that concept this research work attempts to derive a three dimensional model of the seismically active parts of the underlying underground faults in areas of petroleum interest. For that purpose seismic spatio-temporal clustering has been applied to seismic data to identify potential distinct seismic regions in the area of interest. Results have been coalesced with two dimensional maps of underground faults from past surveys and seismic epicentres, having followed careful reallocation processing, have been used to provide information regarding the vertical extent of multiple underground faults in the region of interest. The end product is a three dimensional map of the possible underground location and extent of the seismically active parts of underground faults. Indexing terms: underground faults modelling, seismic data mining, 3D visualisation, active seismic source mapping, seismic hazard evaluation, dangerous phenomena modelling Acknowledgment This research work is supported by the ESPA Operational Programme, Education and Life Long Learning, Students Practical Placement Initiative. References [1] Alves, T.M., Kokinou, E. and Zodiatis, G.: 'A three-step model to assess shoreline and offshore susceptibility to oil spills: The South Aegean (Crete) as an analogue for confined marine basins', Marine Pollution Bulletin, In Press, 2014 [2] Ciappa, A., Costabile, S.: 'Oil spill hazard assessment using a reverse trajectory method for the Egadi marine protected area (Central Mediterranean Sea)', Marine Pollution Bulletin, vol. 84 (1-2), pp. 44-55, 2014 [3] Ganas, A., Karastathis, V., Moshou, A., Valkaniotis, S., Mouzakiotis

Influence of seismic anisotropy on the cross correlation tensor: numerical investigations

NASA Astrophysics Data System (ADS)

Saade, M.; Montagner, J. P.; Roux, P.; Cupillard, P.; Durand, S.; Brenguier, F.

2015-05-01

Temporal changes in seismic anisotropy can be interpreted as variations in the orientation of cracks in seismogenic zones, and thus as variations in the stress field. Such temporal changes have been observed in seismogenic zones before and after earthquakes, although they are still not well understood. In this study, we investigate the azimuthal polarization of surface waves in anisotropic media with respect to the orientation of anisotropy, from a numerical point of view. This technique is based on the observation of the signature of anisotropy on the nine-component cross-correlation tensor (CCT) computed from seismic ambient noise recorded on pairs of three-component sensors. If noise sources are spatially distributed in a homogeneous medium, the CCT allows the reconstruction of the surface wave Green's tensor between the station pairs. In homogeneous, isotropic medium, four off-diagonal terms of the surface wave Green's tensor are null, but not in anisotropic medium. This technique is applied to three-component synthetic seismograms computed in a transversely isotropic medium with a horizontal symmetry axis, using a spectral element code. The CCT is computed between each pair of stations and then rotated, to approximate the surface wave Green's tensor by minimizing the off-diagonal components. This procedure allows the calculation of the azimuthal variation of quasi-Rayleigh and quasi-Love waves. In an anisotropic medium, in some cases, the azimuth of seismic anisotropy can induce a large variation in the horizontal polarization of surface waves. This variation depends on the relative angle between a pair of stations and the direction of anisotropy, the amplitude of the anisotropy, the frequency band of the signal and the depth of the anisotropic layer.

Test and Calibration of the Seismic Research Observatory

USGS Publications Warehouse

Peterson, Jon; Hutt, Charles R.; Holcomb, L. Gary

1980-01-01

Introduction The Seismic Research Observatory (SRO) network is generating an important new data base for seismological research. The SRO systems have extended both the range and resolution of seismic measurements beyond the limits of conventional seismographs and the data are recorded in digital format making it convenient to automate processing and analysis. The SRO network now comprises 12 stations and one additional station will be installed. The data produced by the SRO network, and other digital systems being installed to supplement the SRO network, will be collected by the U.S. Geological Survey's Albuquerque Seismological Laboratory, organized into network-day tapes, and made available to research organizations throughout the world. The network-day tapes are particularly unique and useful data files as they will contain not only seismic data but all of the information needed by an analyst to interpret the data, including station constants and calibration and other instrumental parameters. Hoffman (in preperation) describe these tapes and the format used in their compilation. The global digital data base for seismology is still relatively limited in terms of both geographical and temporal coverage. For this reason there is a tendency, perhaps, to stretch the applicability of the available data beyond the intended purposes. The danger in this is compounded by the fact that computer processing and analysis often can be done without even looking at the waveforms, and it is done with deceptively high computational precision that belies the basic accuracy of the measurements. The day may be passing when seismologists have a hands-on familiarity with the data acquisition systems, but clearly it is as important as ever that they have a knowledge of the capabilities and limitations of the instruments. The primary objective of the SRO network was to lower the threshold of event detection in the long-period band. This was achieved by using a newly-developed borehole

Borehole seismic monitoring of seismic stimulation at OccidentalPermian Ltd's -- South Wason Clear Fork Unit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daley, Tom; Majer, Ernie

2007-04-30

Seismic stimulation is a proposed enhanced oil recovery(EOR) technique which uses seismic energy to increase oil production. Aspart of an integrated research effort (theory, lab and field studies),LBNL has been measuring the seismic amplitude of various stimulationsources in various oil fields (Majer, et al., 2006, Roberts,et al.,2001, Daley et al., 1999). The amplitude of the seismic waves generatedby a stimulation source is an important parameter for increased oilmobility in both theoretical models and laboratory core studies. Theseismic amplitude, typically in units of seismic strain, can be measuredin-situ by use of a borehole seismometer (geophone). Measuring thedistribution of amplitudes within amore » reservoir could allow improved designof stimulation source deployment. In March, 2007, we provided in-fieldmonitoring of two stimulation sources operating in Occidental (Oxy)Permian Ltd's South Wasson Clear Fork (SWCU) unit, located near DenverCity, Tx. The stimulation source is a downhole fluid pulsation devicedeveloped by Applied Seismic Research Corp. (ASR). Our monitoring used aborehole wall-locking 3-component geophone operating in two nearbywells.« less

Seismic Performance of Self-Consolidating Concrete Bridge Columns : Research Brief

DOT National Transportation Integrated Search

2017-09-01

Rectangular bridge columns in high seismic areas require high amounts of confining steel. Self-consolidating concrete is ideal for the construction of concrete members with high steel congestion. However, there is lack of data on the seismic performa...

Seismic investigation of Infiltration Through a Playa of the Llano Estacado Region of Texas

NASA Astrophysics Data System (ADS)

Fernandez-Canel, A.; Gurrola, H.; Taylor, L.; Abila, H.; Oviedo, R.; Harry, E.; Garza, J.

2017-12-01

Most of the population and economy of the south central United States (the bread baskets of the United States) is heavily dependent on the Ogallala aquifer as the main water resource. The overexploitation of the Ogallala aquifer can have catastrophic consequences. This project is a seismic investigation of the hydraulic behavior of the playa lakes of the southern high plains which are considered the main recharge source for the Ogallala. We deployed Texans (Ref Tek RT125A) data loggers with 4.5 Hz single component geophones before and after rain events and after controlled infiltration test to provide a data set to investigate infiltration pathways through the playas. The playa is about eight miles northeast of Lubbock, Texas. We refer to it as compartmentalized because it appears to be two very closely spaced playa; one of which retains water more efficiently than the other. The infiltration tests included the use of 4x8 foot infiltrometers and a 50 foot soaker hose in a compartmentalized playa. Preliminary results from analysis of two repeated profiles suggest that the seismic velocities beneath the infiltrometers and the soaker hose were lower than before flooding. These results suggest that measurements of seismic P-wave velocities may be useful to model the pathway for infiltration through the subsurface of the playa. We have collected (and will continue to collect) additional data sets following rain storms and infiltration test for a few months. We will present the results of these tests at the AGU meeting.

The present status of reservoir induced seismicity investigations with special emphasis on Koyna earthquakes

NASA Astrophysics Data System (ADS)

Gupta, Harsh K.

1985-10-01

The status of Reservoir Induced Seismicity (RIS) has been reviewed periodically (Rothé, 1968, 1973; Gupta and Rastogi, 1976; Simpson, 1976; Packer et al., 1979). In the present paper, the significant work carried out during the last three years on RIS is reviewed. An earthquake of magnitude 5 {1}/{2} occurred on November 14, 1981 in the vicinity of Aswan Lake, Egypt, 17 years after the filling started in 1964. This event occurred 4 days after the seasonal maximum in the reservoir water level and was followed by a long sequence of aftershocks. Another event of magnitude 4 {1}/{2} occurred in the vicinity of Aswan Lake on August 20, 1982. Results of preliminary investigations indicate that this seismic activity is reservoir induced. Recent analyses of induced seismic events at Nurek Reservoir U.S.S.R., show that the second stage of filling during August to December 1976, increasing the maximum depth from 120 m to 200 m, was accompanied by an intense burst of shallow seismic activity. An outward migration from the centre of the reservoir, possibly associated with diffusion of pore pressure, is revealed by the temporal distribution of earthquake foci. A variety of investigations including the in situ measurement of tectonic stress, pore pressure, permeability, distribution of faults, etc., in addition to monitoring seismicity, have been undertaken in the vicinity of the Monticello Reservoir, South Carolina. The largest reservoir induced earthquake is predicted not to exceed magnitude 5. The Koyna Reservoir, India, continues to be the most outstanding example of RIS. Three earthquakes of magnitude $˜5 occurred in September 1980. Earthquakes of magnitude 4 occur frequently in the vicinity of Koyna, the latest being on February 5, 1983. Events that occurred during the period 1967-1973 have been relocated using better procedures and are found to be much shallower and the epicentres less diffused. Location of 12 earthquakes of Ms ⩾ 4.0, their foreshocks and aftershocks

EMERALD: A Flexible Framework for Managing Seismic Data

NASA Astrophysics Data System (ADS)

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

2010-12-01

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

Crustal seismic anisotropy and structure from textural and seismic investigations in the Cycladic region, Greece

NASA Astrophysics Data System (ADS)

Cossette, Élise; Schneider, David; Audet, Pascal; Grasemann, Bernhard

2016-04-01

Seismic anisotropy data are often used to resolve rock structures and deformation styles in the crust based on compilations of rock properties that may not be representative of the exposed geology. We use teleseismic receiver functions jointly with in situ rock property data to constrain the seismic structure and anisotropy of the crust in the Cyclades, Greece, located in the back arc region of the Hellenic subduction zone. Crystallographic preferred orientations (CPOs) via electron backscatter diffraction (EBSD) analyses were measured on a suite of samples representative of different structural depths along the West Cycladic Detachment System; average seismic properties of the rocks were calculated with the Voigt-Reuss-Hill average of the single minerals' elastic stiffness tensor. The calcitic and quartzitic rocks have P- and S-wave velocity anisotropies (AVp, AVs) averaging 8.1% and 7.1%, respectively. The anisotropy increases with depth represented by blueschist assemblages, with AVp averaging 20.3% and AVs averaging 14.5% due to the content of aligned glaucophane and mica, which strongly control the seismic properties of the rocks. Localized anisotropies of very high magnitude are caused by the presence of mica schists as they possess the strongest anisotropies, with values of ~25% for AVp and AVs. The direction of the fast and slow P-wave velocities occur parallel and perpendicular to the foliation, respectively, for most samples. The fast propagation has the same NE-SW orientation as the lithospheric stretching direction present in the Cyclades since the Late Oligocene. The maximum shear wave anisotropy is subhorizontal, similarly concordant with mineral alignment that developed during back-arc extension. Our results strongly favor radial anisotropy in the Aegean mid-crust over azimuthal anisotropy. The receiver function data indicate that the Moho is relatively flat at 25 km depth in the south and deepens to 33 km in the north, consistent with previous

Adding seismic broadband analysis to characterize Andean backarc seismicity in Argentina

NASA Astrophysics Data System (ADS)

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.

Research on Influencing Factors and Generalized Power of Synthetic Artificial Seismic Wave

NASA Astrophysics Data System (ADS)

Jiang, Yanpei

2018-05-01

Start your abstract here… In this paper, according to the trigonometric series method, the author adopts different envelope functions and the acceleration design spectrum in Seismic Code For Urban Bridge Design to simulate the seismic acceleration time history which meets the engineering accuracy requirements by modifying and iterating the initial wave. Spectral analysis is carried out to find out the the distribution law of the changing frequencies of the energy of seismic time history and to determine the main factors that affect the acceleration amplitude spectrum and energy spectrum density. The generalized power formula of seismic time history is derived from the discrete energy integral formula and the author studied the changing characteristics of generalized power of the seismic time history under different envelop functions. Examples are analyzed to illustrate that generalized power can measure the seismic performance of bridges.

Contribution to the study of historical seismicity in the Maghrebian region, Catalogue of historiacal seismicity of the Maghreb region

NASA Astrophysics Data System (ADS)

Elmrabet, T.

2009-04-01

The seismic risk assessment in countries with moderate seismic activity is a very delicate action as well as a high priority one in land use management and urban rehabilitation. The credibility of this assessment is based mainly on the effects of destructive earthquakes whose maximum intensities become a reference for determining the level of protection. This knowledge requires a detailed study of the damage caused by major earthquakes over a long period of time. In this context, a broad scale research about past earthquakes started in the Geophysics Laboratory, now called the National Geophysics Institute (ING) within the National Center for Scientific and Technical Research in Rabat, Morocco. It supported a thorough study which included critical historical texts scattered in various local and foreign archives. The pursuit of this study, under the project called PAMERAR, which was launched in the early 80's aimed at reducing of earthquake risk in the Arab region, led us to investigate the origin of these texts according to various public and private libraries, as in Spain and France. The scientific interest in the historical seismicity in Morocco was highlighted at the beginning of the twentieth century in several reports and catalogs but with several gaps in time and space, further research was thus necessary especially to explore documents in particular from origin sources. This interest in historical archives is within the scope of understanding the natural hazards over long period to evaluate the recurrence of earthquakes. This study leads to significant results covering 11 centuries, from AD 846 to the present. We continued to study the effects of recent earthquakes on humans and buildings heritage, this work has led to a study in the footsteps of local seismic culture. Since earthquakes do not recognize the limits of political geography, since 1993 we have undertaken to extend the research to include the entire Maghreb region. We then used the database

Evaluation of Seismic Risk of Siberia Territory

NASA Astrophysics Data System (ADS)

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

The outcomes of modern geophysical researches of the Geophysical Survey SB RAS, directed on study of geodynamic situation in large industrial and civil centers on the territory of Siberia with the purpose of an evaluation of seismic risk of territories and prediction of origin of extreme situations of natural and man-caused character, are pre- sented in the paper. First of all it concerns the testing and updating of a geoinformation system developed by Russian Emergency Ministry designed for calculations regarding the seismic hazard and response to distructive earthquakes. The GIS database contains the catalogues of earthquakes and faults, seismic zonation maps, vectorized city maps, information on industrial and housing fund, data on character of building and popula- tion in inhabited places etc. The geoinformation system allows to solve on a basis of probabilistic approaches the following problems: - estimating the earthquake impact, required forces, facilities and supplies for life-support of injured population; - deter- mining the consequences of failures on chemical and explosion-dangerous objects; - optimization problems on assurance technology of conduct of salvage operations. Using this computer program, the maps of earthquake risk have been constructed for several seismically dangerous regions of Siberia. These maps display the data on the probable amount of injured people and relative economic damage from an earthquake, which can occur in various sites of the territory according to the map of seismic zona- tion. The obtained maps have allowed determining places where the detailed seismo- logical observations should be arranged. Along with it on the territory of Siberia the wide-ranging investigations with use of new methods of evaluation of physical state of industrial and civil establishments (buildings and structures, hydroelectric power stations, bridges, dams, etc.), high-performance detailed electromagnetic researches of ground conditions of city

Proceedings of the 22nd Annual DoD/DOE Seismic Research Symposium: Planning for Verification of and Compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nichols, James W., LTC

2000-09-15

These proceedings contain papers prepared for the 22nd Annual DoD/DOE Seismic Research Symposium: Planning for Verification of and Compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), held 13-15 September 2000 in New Orleans, Louisiana. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Defense Threat Reduction Agency (DTRA), Air Force Technical Applications Center (AFTAC), Department of Defense (DoD), US Army Space and Missile Defense Command, Defense Special Weapons Agency (DSWA), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate,more » and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

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

NASA Astrophysics Data System (ADS)

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.

Seismic Risk Perception compared with seismic Risk Factors

NASA Astrophysics Data System (ADS)

Crescimbene, Massimo; La Longa, Federica; Pessina, Vera; Pino, Nicola Alessandro; Peruzza, Laura

2016-04-01

The communication of natural hazards and their consequences is one of the more relevant ethical issues faced by scientists. In the last years, social studies have provided evidence that risk communication is strongly influenced by the risk perception of people. In order to develop effective information and risk communication strategies, the perception of risks and the influencing factors should be known. A theory that offers an integrative approach to understanding and explaining risk perception is still missing. To explain risk perception, it is necessary to consider several perspectives: social, psychological and cultural perspectives and their interactions. This paper presents the results of the CATI survey on seismic risk perception in Italy, conducted by INGV researchers on funding by the DPC. We built a questionnaire to assess seismic risk perception, with a particular attention to compare hazard, vulnerability and exposure perception with the real data of the same factors. The Seismic Risk Perception Questionnaire (SRP-Q) is designed by semantic differential method, using opposite terms on a Likert scale to seven points. The questionnaire allows to obtain the scores of five risk indicators: Hazard, Exposure, Vulnerability, People and Community, Earthquake Phenomenon. The questionnaire was administered by telephone interview (C.A.T.I.) on a statistical sample at national level of over 4,000 people, in the period January -February 2015. Results show that risk perception seems be underestimated for all indicators considered. In particular scores of seismic Vulnerability factor are extremely low compared with house information data of the respondents. Other data collected by the questionnaire regard Earthquake information level, Sources of information, Earthquake occurrence with respect to other natural hazards, participation at risk reduction activities and level of involvement. Research on risk perception aims to aid risk analysis and policy-making by

Seismically induced landslides: current research by the US Geological Survey.

USGS Publications Warehouse

Harp, E.L.; Wilson, R.C.; Keefer, D.K.; Wieczorek, G.F.

1986-01-01

We have produced a regional seismic slope-stability map and a probabilistic prediction of landslide distribution from a postulated earthquake. For liquefaction-induced landslides, in situ measurements of seismically induced pore-water pressures have been used to establish an elastic model of pore pressure generation. -from Authors

New Madrid Seismic Zone: a test case for naturally induced seismicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nava, S.J.

1983-09-01

Induced seismicity caused by man-made events, such as the filling of reservoirs has been well documented. In contrast, naturally induced seismicity has received little attention. It has been shown that a fluctuation of as little as several bars can trigger reservoir induced earthquakes. Naturally occurring phenomena generate similar fluctuations and could trigger earthquakes where the faults in ambient stress field are suitably oriented and close to failure. The New Madrid Seismic Zone (NMSZ) presents an ideal test case for the study of naturally induced seismicity. The ideal data set for a study of triggering effects must contain a statistically significantmore » number of events, a constant accumulated strain, and a limited focal region. New Madrid earthquakes are well documented from 1974 to the present, down to a magnitude approx. 1.8. They lie in a distinct fault pattern and occur as a reaction to the regional stress regime. A statistical correlation was made between the earthquakes and a variety of different types of loads, to see if New Madrid seismicity could be triggered by natural fluctuations. The types of triggers investigated ranged from solid earth tides to variations in barometric pressure, rainfall, and stages of the Mississippi River. This analysis becomes complex because each factor investigated creates individual stresses, as well as having imbedded in it a reaction to other factors.« less

Proceedings of the Annual PL/DARPA Seismic Research Symposium (13th), Held in Keystone, Colorado on 8-10 October 1991

DTIC Science & Technology

1991-08-30

PL-TR-91-2208 AD-A241 325Q ~~I 1111111111I IEI N PROCEEDINGS OF THE 13TH ANNUAL PL/DARPA SEISMIC RESEARCH SYMPOSIUM, 8-10 OCTOBER 1991 EDITORS: James...S pTiIUgdjF- SEISMIC RESEARCH S’YMPOSIUMH, 8-10 OCTOBER 1991 PR 2309 6. AUTHOR(S) TA G2 Editors: James F. Lewkowicz Jeanne M. McPhetres 7. PERFORMING...Drive Arlington, VA 22203-1714 11. SUPPLEMENTARY NOTES This research was supported by DARPA under PE 62714E. 12a. DISTRIBUTION / AVAILABILITY STATEMENT

Seismic Risk Mitigation of Historical Minarets Using SMA Wire Dampers

NASA Astrophysics Data System (ADS)

El-Attar, Adel G.; Saleh, Ahmed M.; El-Habbal, Islam R.

2008-07-01

This paper presents the results of a research program sponsored by the European Commission through project WIND-CHIME (Wide Range Non-INtrusive Devices toward Conservation of HIstorical Monuments in the MEditerranean Area), in which the possibility of using advanced seismic protection technologies to preserve historical monuments in the Mediterranean area is investigated. In the current research, two outstanding Egyptian Mamluk-Style minarets, are investigated. The first is the southern minaret of Al-Sultaniya (1340 A.D, 739 Hijri Date (H.D.)), the second is the minaret of Qusun minaret (1337 A.D, 736 H.D.), both located within the city of Cairo. Based on previous studies on the minarets by the authors, a seismic retrofit technique is proposed. The technique utilizes shape memory alloy (SMA) wires as dampers for the upper, more flexible, parts of the minarets in addition to vertical pre-stressing of the lower parts found to be prone to tensile cracking under ground excitation. The effectiveness of the proposed technique is numerically evaluated via nonlinear transient dynamic analyses. The results indicate the effectiveness of the technique in mitigating the seismic hazard, demonstrated by the effective reduction in stresses and in dynamic response.

A numerical and experimental investigation on seismic anisotropy of Finero Peridotite, Ivrea-Verbano Zone, northern Italy

NASA Astrophysics Data System (ADS)

Zhong, Xin; Frehner, Marcel; Zappone, Alba; Kunze, Karsten

2014-05-01

We present a combined experimental and numerical study on Finero Peridotite to investigate the major factors creating its seismic anisotropy. We extrapolate the ultrasonic seismic wave velocity measured in a hydrostatic pressure vessel to 0 MPa and 250 MPa confining pressure to compare with numerical simulations at atmospheric pressure and to restore the velocity at in-situ lower crustal conditions, respectively. A linear relation between confining pressure and seismic velocity above 80 MPa reveals the intrinsic mechanical property of the bulk rock without the interference of cracks. To visualize the crystallographic preferred orientation (CPO) we use the electron backscatter diffraction (EBSD) method and create crystallographic orientation maps and pole figures. The first also reveals the shape preferred orientation (SPO). We found that very weak CPO but significant SPO exist in most of the peridotite. The Voigt and Reuss bounds as well as the Hill average (VRH) are calculated from EBSD data to visualize seismic velocity and to calculate anisotropy in the form of velocity pole figures. We perform finite element (FE) simulations of wave propagation on the EBSD crystallographic orientation maps to calculate the effective wave velocity at different propagation angles, hence estimate the anisotropy numerically. In fracture-free models the FE simulation results agree well with the Hill average. In one case of a sample containing fractures the FE simulation yields similar minimal velocity as the laboratory measurement, which lies outside the VR bounds. This is a warning that care has to be taken when using VRH averages in fractured rocks. All three velocity estimates (hydrostatic pressure vessel, VRH average, and FE simulation) result in equally weak seismic anisotropy. This is mainly the consequence of weak CPO. Although SPO is significantly stronger it has minor influence on anisotropy. Hydrous minerals influence the seismic anisotropy only when their modal

Miscellaneous High-Resolution Seismic Imaging Investigations in Salt Lake and Utah Valleys for Earthquake Hazards

USGS Publications Warehouse

Stephenson, W.J.; Williams, R.A.; Odum, J.K.; Worley, D.M.

2007-01-01

Introduction In support of earthquake hazards and ground motion studies by researchers at the Utah Geological Survey, University of Utah, Utah State University, Brigham Young University, and San Diego State University, the U.S. Geological Survey Geologic Hazards Team Intermountain West Project conducted three high-resolution seismic imaging investigations along the Wasatch Front between September 2003 and September 2005. These three investigations include: (1) a proof-of-concept P-wave minivib reflection imaging profile in south-central Salt Lake Valley, (2) a series of seven deep (as deep as 400 m) S-wave reflection/refraction soundings using an S-wave minivib in both Salt Lake and Utah Valleys, and (3) an S-wave (and P-wave) investigation to 30 m at four sites in Utah Valley and at two previously investigated S-wave (Vs) minivib sites. In addition, we present results from a previously unpublished downhole S-wave investigation conducted at four sites in Utah Valley. The locations for each of these investigations are shown in figure 1. Coordinates for the investigation sites are listed in Table 1. With the exception of the P-wave common mid-point (CMP) reflection profile, whose end points are listed, these coordinates are for the midpoint of each velocity sounding. Vs30 and Vs100, also shown in Table 1, are defined as the average shear-wave velocities to depths of 30 and 100 m, respectively, and details of their calculation can be found in Stephenson and others (2005). The information from these studies will be incorporated into components of the urban hazards maps along the Wasatch Front being developed by the U.S. Geological Survey, Utah Geological Survey, and numerous collaborating research institutions.

A novel EBSD-based finite-element wave propagation model for investigating seismic anisotropy: Application to Finero Peridotite, Ivrea-Verbano Zone, Northern Italy

NASA Astrophysics Data System (ADS)

Zhong, Xin; Frehner, Marcel; Kunze, Karsten; Zappone, Alba

2014-10-01

A novel electron backscatter diffraction (EBSD) -based finite-element (FE) wave propagation simulation is presented and applied to investigate seismic anisotropy of peridotite samples. The FE model simulates the dynamic propagation of seismic waves along any chosen direction through representative 2D EBSD sections. The numerical model allows separation of the effects of crystallographic preferred orientation (CPO) and shape preferred orientation (SPO). The obtained seismic velocities with respect to specimen orientation are compared with Voigt-Reuss-Hill estimates and with laboratory measurements. The results of these three independent methods testify that CPO is the dominant factor controlling seismic anisotropy. Fracture fillings and minor minerals like hornblende only influence the seismic anisotropy if their volume proportion is sufficiently large (up to 23%). The SPO influence is minor compared to the other factors. The presented FE model is discussed with regard to its potential in simulating seismic wave propagation using EBSD data representing natural rock petrofabrics.

Seismic Investigations of the Murci Geothermal Field (Southern Tuscany, Italy): Preliminary Results

NASA Astrophysics Data System (ADS)

Riedel, M.; Alexandrakis, C.; Buske, S.

2013-12-01

The Monte Amiata region in the Southern Tuscany, Central Italy, describes a volcanic complex with great significance in terms of the regional fresh water supply, mining and geothermal power generation. Mainly for the latter purpose, the volcanic area of Mt Amiata has been the subject of extensive geological and geophysical research (e.g. Dini et al., 2010 and references therein). The insights from these studies have led to successful geothermal production in the Mt Amiata region since the early 1960s (e.g. Batini et al., 2003). Today's most important reservoirs in this area are the Bagnore and the Piancastagnaio fields which are both operated by the company Enel Green Power. The work presented here deals with the Murci area, another potential reservoir located about 10 km southwest of the Mt Amiata volcanic complex. Therefore, in order to get a more detailed understanding of this area, five reflection seismic profiles were carried out. We have performed on three of them a preliminary depth-migrated images, through Kirchhoff prestack depth migration (KPSDM). The vital point of depth migration algorithms is the accuracy of the velocity model that is used for the backpropagation of the seismic data. Therefore, we derived a suitable 1D starting model from nearby well logs and VSP measurements. In order to remove the large topography effects along the profiles, we then utilized first-arrival tomography for each seismic line. For the following processing we incorporated these 2D tomographic results into our starting model which compensates for static effects and improves the resolution in the near-surface area. The velocity models were then used in the application of KPSDM to the seismic data for each profile, respectively. The resulting preliminary images show a zone of high seismic reflectivity, known as the 'K-horizon' (e.g. Brogi, 2008), and could improve its geological interpretation. These promising results encourage us to proceed with deeper migration velocity

Co-seismic slip, post-seismic slip, and largest aftershock associated with the 1994 Sanriku-haruka-oki, Japan, earthquake

NASA Astrophysics Data System (ADS)

Yagi, Yuji; Kikuchi, Masayuki; Nishimura, Takuya

2003-11-01

We analyzed continuous GPS data to investigate the spatio-temporal distribution of co-seismic slip, post-seismic slip, and largest aftershock associated with the 1994 Sanriku-haruka-oki, Japan, earthquake (Mw = 7.7). To get better resolution for co-seismic and post-seismic slip distribution, we imposed a weak constraint as a priori information of the co-seismic slip determined by seismic wave analyses. We found that the post-seismic slip during 100 days following the main-shock amount to as much moment release as the main-shock, and that the sites of co-seismic slip and post-seismic slip are partitioning on a plate boundary region in complimentary fashion. The major post-seismic slip was triggered by the mainshock in western side of the co-seismic slip, and the extent of the post-seismic slip is almost unchanged with time. It rapidly developed a shear stress concentration ahead of the slip area, and triggered the largest aftershock.

Automatic Seismic Signal Processing Research.

DTIC Science & Technology

1981-09-01

be used. We then rave mD(k) AT(k) + b (11) S2 aT S SD(k) - a(k) a so Equation (9) becomes ( Gnanadesikan , 1977, p. 83; Young and Calvert, 1974, Equation... Gnanadesikan (1977, p. 196), "The main function of statistical data analysis is to extricate and explicate the informational content of a body of...R. C. Goff (1980), "Evaluation of the MARS Seismic Event Detector," Systems, Science and Software Report SSS-R-81-4656, August. Gnanadesikan , R

Investigation on the characteristics of seismic events observed during stimulation of geothermal reservoirs at Basel, Switzerland

NASA Astrophysics Data System (ADS)

Mukuhira, Y.; Asanuma, H.; Niitsuma, H.; Häring, M. O.

2011-12-01

Hydraulic stimulation is commonly used to develop engineered geothermal systems (EGS) and enhancement of oil recovery (EOR). Occurrence of seismic events with larger magnitude has been highlighted as one of the practical and critical problems. Some seismic events with moment magnitude (Mw) larger than 2.0 occurred during and after hydraulic stimulation in Basel, Switzerland, in 2006, and these large events led to the geothermal project discontinued. We defined the large event as seismic events with Mw>2.0, and have investigated fundamental characteristics of them as summarized in Table 1. It has been revealed that the characteristics of the large events are dependent on hypocentral location and origin time. We also found most of the large events occurred from 2 types of fracture planes: 6 of 9large events had FPSs with N-S azimuth. Other 3 large events including the largest events had FPSs ESE-WNW azimuth, which can be interpreted as "most slip-able" under stress state at Basel. The large events clearly followed "constant stress drop scaling law". We also estimated critical pore pressure for shear slip using Coulomb failure criterion, and have revealed that the critical pore pressure of the large events was relatively lower. Our result shows that the occurrences of the large events can not be simply interpreted by previous experience on induced seismicity.

Permafrost Active Layer Seismic Interferometry Experiment (PALSIE).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abbott, Robert; Knox, Hunter Anne; James, Stephanie

2016-01-01

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

An interdisciplinary perspective on social and physical determinants of seismic risk

NASA Astrophysics Data System (ADS)

Lin, K.-H.; Chang, Y.-C.; Liu, G.-Y.; Chan, C.-H.; Lin, T.-H.; Yeh, C.-H.

2015-01-01

While disaster studies researchers usually view risk as a function of hazard, exposure, and vulnerability, few studies have systematically examined the relationships among the various physical and socioeconomic determinants underlying disasters, and fewer have done so through seismic risk analysis. In the context of the 1999 Chi-Chi earthquake in Taiwan, this study constructs five hypothetical models to test different determinants that affect disaster fatality at the village level, namely seismic hazard intensity, population, building fragility, demographics and socioeconomics. The Poisson Regression Model is used to estimate the impact of natural hazards and social factors on fatality. Results indicate that although all of the determinants have an impact on the specific dimension of seismic fatality, some indicators of social inequality, such as gender ratio, dependency ratio, income and its SD, are the driving determinants deteriorating vulnerability to seismic risk. These findings have strong social implications for policy interventions to mitigate such disasters. This study presents an interdisciplinary investigation into social and physical determinants in seismic risk.

Statistical methods for investigating quiescence and other temporal seismicity patterns

USGS Publications Warehouse

Matthews, M.V.; Reasenberg, P.A.

1988-01-01

We propose a statistical model and a technique for objective recognition of one of the most commonly cited seismicity patterns:microearthquake quiescence. We use a Poisson process model for seismicity and define a process with quiescence as one with a particular type of piece-wise constant intensity function. From this model, we derive a statistic for testing stationarity against a 'quiescence' alternative. The large-sample null distribution of this statistic is approximated from simulated distributions of appropriate functionals applied to Brownian bridge processes. We point out the restrictiveness of the particular model we propose and of the quiescence idea in general. The fact that there are many point processes which have neither constant nor quiescent rate functions underscores the need to test for and describe nonuniformity thoroughly. We advocate the use of the quiescence test in conjunction with various other tests for nonuniformity and with graphical methods such as density estimation. ideally these methods may promote accurate description of temporal seismicity distributions and useful characterizations of interesting patterns. ?? 1988 Birkha??user Verlag.

Time-reversibility in seismic sequences: Application to the seismicity of Mexican subduction zone

NASA Astrophysics Data System (ADS)

Telesca, L.; Flores-Márquez, E. L.; Ramírez-Rojas, A.

2018-02-01

In this paper we investigate the time-reversibility of series associated with the seismicity of five seismic areas of the subduction zone beneath the Southwest Pacific Mexican coast, applying the horizontal visibility graph method to the series of earthquake magnitudes, interevent times, interdistances and magnitude increments. We applied the Kullback-Leibler divergence D that is a metric for quantifying the degree of time-irreversibility in time series. Our findings suggest that among the five seismic areas, Jalisco-Colima is characterized by time-reversibility in all the four seismic series. Our results are consistent with the peculiar seismo-tectonic characteristics of Jalisco-Colima, which is the closest to the Middle American Trench and belongs to the Mexican volcanic arc.

Geothermal Potential of the Siǧacik Gulf (Seferihisar) and Preliminary investigations with Seismic and Magnetic Surveys

NASA Astrophysics Data System (ADS)

Bakak, Özde; Özel, Erdeniz; Ergün, Mustafa

2015-04-01

The Aegean region, including both W. Turkey and Central Greece, is one of the world's most rapidly-deforming regions of continental crust and has a seismic rate is exceptional on a world scale. SW Turkey is one of the most rapidly extending regions in the world where the extension appears to have commenced in middle or late Miocene time. Paleomagnetic work in W Turkey and Aegean islands has revealed the horizontal rotation of some crustal blocks. In W Turkey clockwise rotation on Karaburun peninsula west of Izmir by 44° in the last few Ma is detected, and anticlockwise rotation of 37° for the Seferihisar region. The area of W Turkey and the Aegean islands has very strong geothermal gradient in the world scale. Sığacık Gulf is located on south of Karaburun Peninsula, and it is restricted by two important ridges as Karaburun and Seferihisar Ridges. Recent geological and geophysical studies suggested that this area is both E-W trending normal and NE-SW trending strike-slip faulting caused deformation. The Seferihisar earthquake series were occurred here during 17-20 October 2005. For investigation of geothermal potential and hot water outlets on the seafloor, shallow seismic and magnetic surveys are preferred, which were carried out onboard Dokuz Eylül-1 vessel belongs to Dokuz Eylül University, in 2011. Approximately 250km seismic reflection data was collected along 27 lines. During seismic method used Sparker system which has 1 channel and 12 hydrophone with 17 m long streamer, as a seismic source used SIG Seismic Marine ELC 80 (4 kV & 3.2 KV DC). Seismic data processing (band pass filter, bottom mute, top mute, true amplitude recovery, time migration) was made using Promax program in the Seismic Laboratory in the Institute of Marine Science and Technology. The basement topography map was prepared using Kingdom Suite program drawing seabed line on these sections. Sea floor topography changes between 30-120 m, and this increases towards Ikaria Basin

Laboratory investigations of seismicity caused by iceberg calving and capsize

NASA Astrophysics Data System (ADS)

Cathles, L. M. M., IV; Kaluzienski, L. M.; Burton, J. C.

2015-12-01

The calving and capsize of cubic kilometer-sized icebergs in both Greenland and Antarctica are known to be the source of long-period seismic events classified as glacial earthquakes. The ability to monitor both calving events and the mass of ice calved using the Global Seismographic Network is quite attractive, however, the basic physics of these large calving events must be understood to develop a robust relationship between seismic magnitude and mass of ice calved. The amplitude and duration of the seismic signal is expected to be related to the mass of the calved iceberg and the magnitude of the acceleration of the iceberg's center of mass, yet a simple relationship between these quantities has proved difficult to develop from in situ observations or numerical models. To address this, we developed and carried out a set of experiments on a laboratory scale model of iceberg calving. These experiments were designed to measure several aspects of the post-fracture calving process. Our results show that a combination of mechanical contact forces and hydrodynamic pressure forces are generated by the capsize of an iceberg adjacent to a glacier's terminus. These forces combine to produce the net horizontal centroid single force (CSF) which is often used to model glacial earthquake sources. We find that although the amplitude and duration of the force applied to the terminus generally increases with the iceberg mass, the details depend on the geometry of the iceberg and the depth of the water. The resulting seismic signal is thus crucially dependent on hydrodynamics of the capsize process.

Regional Observation of Seismic Activity in Baekdu Mountain

NASA Astrophysics Data System (ADS)

Kim, Geunyoung; Che, Il-Young; Shin, Jin-Soo; Chi, Heon-Cheol

2015-04-01

Seismic unrest in Baekdu Mountain area between North Korea and Northeast China region has called attention to geological research community in Northeast Asia due to her historical and cultural importance. Seismic bulletin shows level of seismic activity in the area is higher than that of Jilin Province of Northeast China. Local volcanic observation shows a symptom of magmatic unrest in period between 2002 and 2006. Regional seismic data have been used to analyze seismic activity of the area. The seismic activity could be differentiated from other seismic phenomena in the region by the analysis.

Experimental investigation of the seismic response of bridge bearings.

DOT National Transportation Integrated Search

2013-05-01

The Illinois Department of Transportation (IDOT) commonly uses elastomeric bearings to accommodate thermal : deformations in bridges. These bearings also present an opportunity to achieve a structural response similar to isolation : during seismic ev...

Investigating glide snow avalanche release using seismic monitoring in combination with time-lapse photography

NASA Astrophysics Data System (ADS)

van Herwijnen, Alec; Failletaz, Jerome; Berhod, Nicole; Mitterer, Christoph

2013-04-01

Glide avalanches occur when the entire snowpack glides over the ground until an avalanche releases. These avalanches are difficult to forecast since the gliding process can take place over a few hours up to several weeks or months. The presence of liquid water at the interface between the snow cover and the ground surface is of primary importance as it reduces frictional support. Glide avalanches are often preceded by the opening of a tensile crack in the snow cover, called a glide crack. Past research has shown that glide crack opening accelerates prior to avalanche release. During the winter of 2012-2013, we monitored glide crack expansion using time-lapse photography in combination with a seismic sensor and two heat flux sensors on a slope with well documented glide avalanche activity in the Eastern Swiss Alps above Davos, Switzerland. To track changes in glide rates, the number of dark pixels in an area around the glide crack is counted in each image. Using this technique, we observed an increase in glide rates prior to avalanche release. Since the field site is located very close to the town of Davos, the seismic data was very noisy. Nevertheless, the accelerated snow gliding observed in the time-lapse images coincided with increased seismic activity. Overall, these results show that a combination of time-lapse photography with seismic monitoring could provide valuable insight into glide avalanche release. Recordings of the heat flux plates show that the energy input from the soil is fairly small and constant throughout the observed period. The results suggest that ground heat flux is a minor contributor to the water production at the snow-soil interface. Instead, the presence of water at the base of the snowpack is probably due to a strong hydraulic pressure gradient at the snow-soil interface.

Using Ambient Noise for Investigating Cultural Heritage Sites and Evaluating Seismic Site Response

NASA Astrophysics Data System (ADS)

D'Amico, S.; Farrugia, D.; Galea, P. M.; Ruben, B. P., Sr.

2016-12-01

Recordings of ambient noise as well as use of the HVSR technique represent a common tool for evaluating seismic site response. In this study we applied such techniques to several cultural heritage sites located on the Maltese archipelago (Central Mediterranean). In particular, two of the Maltese watchtowers, built by the Knights of St. John between 1637 and 1659, were investigated together with the megalithic temple site of Mnajdra. Array data were acquired using the Micromed SoilSpy Rosina™ equipped with 4.5 Hz vertical geophones, setting the array in an L-shaped configuration. The Extended Spatial Autocorrelation (ESAC) technique was used to extract Rayleigh-wave dispersion curves. Moreover, single-station data close to the array was collected using a Tromino 3-component seismograph (www.tromino.eu), and the H/V curves were extracted. The dispersion curves and the H/V curves were jointly inverted using the Genetic Algorithm (GA) to obtain the shear-wave velocity profile. A fixed number of layers was used in the inversion and ranges for the layer thickness, P-wave and S-wave velocity, and density were specified. The obtained velocity profiles were used to compute the amplification function for the site based on the square root of the effective seismic impedance, also known as the quarter-wavelength approximation. This was used in the simulation of ground motion parameters at the site for various earthquakes using the stochastic one-dimensional site response analysis algorithm, Extended Source Simulation (EXSIM). In addition, the fundamental period and the damping ratio of the watchtowers was obtained by recording ambient vibrations. In the megalithic temples we were also able to evaluate the coverage of the soil deposits within the structure, comparing our results with previous study that used different geophysical techniques. In conclusion, this study enables us to map the seismic amplification hazard and provides primary data on the seismic risk assessment of

Laboratory Investigation of the Effect of Water-Saturation on Seismic Wave Dispersion in Carbonates

NASA Astrophysics Data System (ADS)

Li, W.; Pyrak-Nolte, L. J.

2009-12-01

functional form of the dependence of the shear wave velocity on frequency is relatively constant with fluid saturation, but the magnitude of the velocity decreased (~35 m/s) with increasing saturation. From theoretical calculations, the shear modulus increased during water invasion and was independent of frequency. However, the changes in the Young’s modulus with water invasion depended on the frequency of observation. When 46.5ml was infused into the sample, the Young’s modulus interpreted from the high-frequency components (wavelength from 1.43mm to 2.4mm) increased 70%, while the modulus from the low-frequency components (wavelengths vary from 1.4cm to 3.4mm) increased between 20% and 55%. Interpreting seismic data to determine fluid saturation in rock with fabric-controlled layering requires an understanding of the seismic dispersion properties of the rock in addition to the ability of fluids on alter or mask the dispersion. Acknowledgments: The authors wish to acknowledge support of this work by the Geosciences Research Program, Office of Basic Energy Sciences US Department of Energy (DEFG02-97ER14785 08), by Exxon Mobil Upstream Research Company and the GeoMathematical Imaging Group at Purdue University.

Induced Seismicity

NASA Astrophysics Data System (ADS)

Keranen, Katie M.; Weingarten, Matthew

2018-05-01

The ability of fluid-generated subsurface stress changes to trigger earthquakes has long been recognized. However, the dramatic rise in the rate of human-induced earthquakes in the past decade has created abundant opportunities to study induced earthquakes and triggering processes. This review briefly summarizes early studies but focuses on results from induced earthquakes during the past 10 years related to fluid injection in petroleum fields. Study of these earthquakes has resulted in insights into physical processes and has identified knowledge gaps and future research directions. Induced earthquakes are challenging to identify using seismological methods, and faults and reefs strongly modulate spatial and temporal patterns of induced seismicity. However, the similarity of induced and natural seismicity provides an effective tool for studying earthquake processes. With continuing development of energy resources, increased interest in carbon sequestration, and construction of large dams, induced seismicity will continue to pose a hazard in coming years.

Seismic reflection imaging with conventional and unconventional sources

NASA Astrophysics Data System (ADS)

Quiros Ugalde, Diego Alonso

This manuscript reports the results of research using both conventional and unconventional energy sources as well as conventional and unconventional analysis to image crustal structure using reflected seismic waves. The work presented here includes the use of explosions to investigate the Taiwanese lithosphere, the use of 'noise' from railroads to investigate the shallow subsurface of the Rio Grande rift, and the use of microearthquakes to image subsurface structure near an active fault zone within the Appalachian mountains. Chapter 1 uses recordings from the land refraction and wide-angle reflection component of the Taiwan Integrated Geodynamic Research (TAIGER) project. The most prominent reflection feature imaged by these surveys is an anomalously strong reflector found in northeastern Taiwan. The goal of this chapter is to analyze the TAIGER recordings and to place the reflector into a geologic framework that fits with the modern tectonic kinematics of the region. Chapter 2 uses railroad traffic as a source for reflection profiling within the Rio Grande rift. Here the railroad recordings are treated in an analogous way to Vibroseis recordings. These results suggest that railroad noise in general can be a valuable new tool in imaging and characterizing the shallow subsurface in environmental and geotechnical studies. In chapters 3 and 4, earthquakes serve as the seismic imaging source. In these studies the methodology of Vertical Seismic Profiling (VSP) is borrowed from the oil and gas industry to develop reflection images. In chapter 3, a single earthquake is used to probe a small area beneath Waterboro, Maine. In chapter 4, the same method is applied to multiple earthquakes to take advantage of the increased redundancy that results from multiple events illuminating the same structure. The latter study demonstrates how dense arrays can be a powerful new tool for delineating, and monitoring temporal changes of deep structure in areas characterized by significant

Research on the spatial analysis method of seismic hazard for island

NASA Astrophysics Data System (ADS)

Jia, Jing; Jiang, Jitong; Zheng, Qiuhong; Gao, Huiying

2017-05-01

Seismic hazard analysis(SHA) is a key component of earthquake disaster prevention field for island engineering, whose result could provide parameters for seismic design microscopically and also is the requisite work for the island conservation planning’s earthquake and comprehensive disaster prevention planning macroscopically, in the exploitation and construction process of both inhabited and uninhabited islands. The existing seismic hazard analysis methods are compared in their application, and their application and limitation for island is analysed. Then a specialized spatial analysis method of seismic hazard for island (SAMSHI) is given to support the further related work of earthquake disaster prevention planning, based on spatial analysis tools in GIS and fuzzy comprehensive evaluation model. The basic spatial database of SAMSHI includes faults data, historical earthquake record data, geological data and Bouguer gravity anomalies data, which are the data sources for the 11 indices of the fuzzy comprehensive evaluation model, and these indices are calculated by the spatial analysis model constructed in ArcGIS’s Model Builder platform.

Slope Stability Analysis In Seismic Areas Of The Northern Apennines (Italy)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lo Presti, D.; Fontana, T.; Marchetti, D.

2008-07-08

Several research works have been published on the slope stability in the northern Tuscany (central Italy) and particularly in the seismic areas of Garfagnana and Lunigiana (Lucca and Massa-Carrara districts), aimed at analysing the slope stability under static and dynamic conditions and mapping the landslide hazard. In addition, in situ and laboratory investigations are available for the study area, thanks to the activities undertaken by the Tuscany Seismic Survey. Based on such a huge information the co-seismic stability of few ideal slope profiles have been analysed by means of Limit equilibrium method LEM - (pseudo-static) and Newmark sliding block analysismore » (pseudo-dynamic). The analysis--results gave indications about the most appropriate seismic coefficient to be used in pseudo-static analysis after establishing allowable permanent displacement. Such indications are commented in the light of the Italian and European prescriptions for seismic stability analysis with pseudo-static approach. The stability conditions, obtained from the previous analyses, could be used to define microzonation criteria for the study area.« less

Seismic performance of an I-girder to inverted-T bent cap connection.

DOT National Transportation Integrated Search

2011-09-01

This report presents the research conducted as part of an investigation for the California Department of Transportation (Caltrans) regarding the seismic response and overall moment capacity of precast I-girder to inverted-T bent cap bridge connection...

Report for explosion and earthquake data acquired in the 1999 Seismic Hazards Investigation of Puget Sound (SHIPS), Washington

USGS Publications Warehouse

Brocher, Thomas M.; Pratt, Thomas L.; Miller, Kate C.; Tréhu, Anne M.; Snelson, Catherine M.; Weaver, Craig S.; Creager, Ken C.; Crosson, Robert S.; ten Brink, Uri S.; Alvarez, Marcos G.; Harder, Steven H.; Asudeh, Isa

2000-01-01

This report describes the acquisition, processing, and quality of seismic reflection and refraction data obtained in the Seattle basin, central Puget Lowland, western Washington, in September 1999 during the Seismic Hazards Investigation of Puget Sound (SHIPS). As a sequel to the 1998 SHIPS air gun experiment (also known as 'Wet SHIPS'), the 1999 experiment, nicknamed 'Dry SHIPS,' acquired a 112-km-long east-west trending multichannel seismic reflection and refraction line in the Seattle basin. One thousand and eight seismographs were deployed at a nominal spacing of 100 meters, and 29 shot points were detonated at approximately 4 km intervals along the seismic line. The wide-angle seismic profile was designed to (1) determine the E-W geometry of Seattle basin, (2) measure the seismic velocities within the basin, and (3) define the basement structure underlying the Seattle basin. In this report, we describe the acquisition of these data, discuss the processing and merging of the data into common shot gathers, and illustrate the acquired profiles. We also describe the format and content of the archival tapes containing the SEGY-formatted, common-shot gathers. Data quality is variable, but useful data were acquired from all 29 shot points fired along the Dry SHIPS seismic line. The data show pronounced travel time delays associated with the low velocity sedimentary rocks filling the Seattle basin. Thirty-five REFTEK stations, deployed at 4 km intervals along the Dry SHIPS line, recorded 26 regional earthquakes and blasts and 17 teleseismic events, including the main shock and several aftershocks of the Mw=7.6 Chi-Chi (Taiwan) earthquake of 9/20/1999. The teleseismic recordings of the Chi-Chi (Taiwan) mainshock provide useful signals down to 10 second periods. They document a significant (factor between 5 and 10) focusing of compressional- and shear-wave energy by the Seattle basin at periods between 1 and 2 seconds relative to 'bedrock' sites east and west of the

Multi-scale investigation into the mechanisms of fault mirror formation in seismically active carbonate rocks

NASA Astrophysics Data System (ADS)

Ohl, Markus; Chatzaras, Vasileios; Niemeijer, Andre; King, Helen; Drury, Martyn; Plümper, Oliver

2017-04-01

Mirror surfaces along principal slip zones in carbonate rocks have recently received considerable attention as they are thought to form during fault slip at seismic velocities and thus may be a marker for paleo-seismicity (Siman-Tov et al., 2013). Therefore, these structures represent an opportunity to improve our understanding of earthquake mechanics in carbonate faults. Recent investigations reported the formation of fault mirrors in natural rocks as well as in laboratory experiments and connected their occurrence to the development of nano-sized granular material (Spagnuolo et al., 2015). However, the underlying formation and deformation mechanisms of these fault mirrors are still poorly constrained and warrant further research. In order to understand the influence and significance of these fault products on the overall fault behavior, we analysed the micro-, and nanostructural inventory of natural fault samples containing mirror slip surfaces. Here we present first results on the possible formation mechanisms of fault mirrors and associated deformation mechanisms operating in the carbonate fault gouge from two seismically active fault zones in central Greece. Our study specifically focuses on mirror slip surfaces obtained from the Arkitsa fault in the Gulf of Evia and the Schinos fault in the Gulf of Corinth. The Schinos fault was reactivated by a magnitude 6.7 earthquake in 1981 while the Arkitsa fault is thought to have been reactivated by a magnitude 6.9 earthquake in 1894. Our investigations encompass a combination of state-of-the-art analytical techniques including X-ray computed tomography, focused ion beam scanning electron microscopy (FIB-SEM), transmission electron microscopy (TEM) and Raman spectroscopy. Using this multiscale analytical approach, we report decarbonation-reaction structures, considerable calcite twinning and grain welding immediately below the mirror slip surface. Grains or areas indicating decarbonation reactions show a foam

High Voltage Seismic Generator

NASA Astrophysics Data System (ADS)

Bogacz, Adrian; Pala, Damian; Knafel, Marcin

2015-04-01

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

Finite-Difference Numerical Simulation of Seismic Gradiometry

NASA Astrophysics Data System (ADS)

Aldridge, D. F.; Symons, N. P.; Haney, M. M.

2006-12-01

We use the phrase seismic gradiometry to refer to the developing research area involving measurement, modeling, analysis, and interpretation of spatial derivatives (or differences) of a seismic wavefield. In analogy with gradiometric methods used in gravity and magnetic exploration, seismic gradiometry offers the potential for enhancing resolution, and revealing new (or hitherto obscure) information about the subsurface. For example, measurement of pressure and rotation enables the decomposition of recorded seismic data into compressional (P) and shear (S) components. Additionally, a complete observation of the total seismic wavefield at a single receiver (including both rectilinear and rotational motions) offers the possibility of inferring the type, speed, and direction of an incident seismic wave. Spatially extended receiver arrays, conventionally used for such directional and phase speed determinations, may be dispensed with. Seismic wave propagation algorithms based on the explicit, time-domain, finite-difference (FD) numerical method are well-suited for investigating gradiometric effects. We have implemented in our acoustic, elastic, and poroelastic algorithms a point receiver that records the 9 components of the particle velocity gradient tensor. Pressure and particle rotation are obtained by forming particular linear combinations of these tensor components, and integrating with respect to time. All algorithms entail 3D O(2,4) FD solutions of coupled, first- order systems of partial differential equations on uniformly-spaced staggered spatial and temporal grids. Numerical tests with a 1D model composed of homogeneous and isotropic elastic layers show isolation of P, SV, and SH phases recorded in a multiple borehole configuration, even in the case of interfering events. Synthetic traces recorded by geophones and rotation receivers in a shallow crosswell geometry with randomly heterogeneous poroelastic models also illustrate clear P (fast and slow) and S

SH-wave reflection seismic and VSP as tools for the investigation of sinkhole areas in Germany

NASA Astrophysics Data System (ADS)

Wadas, Sonja; Tschache, Saskia; Polom, Ulrich; Buness, Hermann; Krawczyk, Charlotte M.

2017-04-01

Sinkholes can lead to damage of buildings and infrastructure and they can cause life-threatening situations, if they occur in urban areas. The process behind this phenomenon is called subrosion. Subrosion is the underground leaching of soluble rocks, e.g. anhydrite and gypsum, due to the contact with ground- and meteoric water. Depending on the leached material, and especially the dissolution rate, different kinds of subrosion structures evolve in the subsurface. The two end members are collapse and depression structures. For a better understanding of the subrosion processes a detailed characterization of the resulting structures is necessary. In Germany sinkholes are a problem in many areas. In northern Germany salt and in central and southern Germany sulfate and carbonate deposits are affected by subrosion. The study areas described here are located in Thuringia in central Germany and the underground is characterized by soluble Permian deposits. The occurrence of 20 to 50 sinkholes is reported per year. Two regions, Bad Frankenhausen and Schmalkalden, are investigated, showing a leaning church tower and a sinkhole of 30 m diameter and 20 m depth, respectively. In Bad Frankenhausen four P-wave and 16 SH-wave reflection seismic profiles were carried out, supplemented by three zero-offset VSPs. In Schmalkalden five SH-wave reflection seismic profiles and one zero-offset VSP were acquired. The 2-D seismic sections, in particular the SH-wave profiles, showed known and unknown near-surface faults in the vicinity of sinkholes and depressions. For imaging the near-surface (< 100 m depth) high-resolution SH-waves are advantageous in order to detect subrosion structures at different stages. The reflection patterns of the 2-D seismic sections indicate a heterogeneous underground with lateral and vertical variations in forms of discontinuous reflectors, depressions, small-scale fractures and near-surface faults. Probably the faults and fractures serve as pathways for

Evaluation Seismicity west of block-lut for Deterministic Seismic Hazard Assessment of Shahdad ,Iran

NASA Astrophysics Data System (ADS)

Ney, B.; Askari, M.

2009-04-01

Evaluation Seismicity west of block-lut for Deterministic Seismic Hazard Assessment of Shahdad ,Iran Behnoosh Neyestani , Mina Askari Students of Science and Research University,Iran. Seismic Hazard Assessment has been done for Shahdad city in this study , and four maps (Kerman-Bam-Nakhil Ab-Allah Abad) has been prepared to indicate the Deterministic estimate of Peak Ground Acceleration (PGA) in this area. Deterministic Seismic Hazard Assessment has been preformed for a region in eastern Iran (Shahdad) based on the available geological, seismological and geophysical information and seismic zoning map of region has been constructed. For this assessment first Seimotectonic map of study region in a radius of 100km is prepared using geological maps, distribution of historical and instrumental earthquake data and focal mechanism solutions it is used as the base map for delineation of potential seismic sources. After that minimum distance, for every seismic sources until site (Shahdad) and maximum magnitude for each source have been determined. In Shahdad ,according to results, peak ground acceleration using the Yoshimitsu Fukushima &Teiji Tanaka'1990 attenuation relationship is estimated to be 0.58 g, that is related to the movement of nayband fault with distance 2.4km of the site and maximum magnitude Ms=7.5.

Proceedings of the 11th Annual DARPA/AFGL Seismic Research symposium

NASA Astrophysics Data System (ADS)

Lewkowicz, James F.; McPhetres, Jeanne M.

1990-11-01

The following subjects are covered: near source observations of quarry explosions; small explosion discrimination and yield estimation; Rg as a depth discriminant for earthquakes and explosions: a case study in New England; a comparative study of high frequency seismic noise at selected sites in the USSR and USA; chemical explosions and the discrimination problem; application of simulated annealing to joint hypocenter determination; frequency dependence of Q(sub Lg) and Q in the continental crust; statistical approaches to testing for compliance with a threshold test ban treaty; broad-band studies of seismic sources at regional and teleseismic distances using advanced time series analysis methods; effects of depth of burial and tectonic release on regional and teleseismic explosion waveforms; finite difference simulations of seismic wave excitation at Soviet test sites with deterministic structures; stochastic geologic effects on near-field ground motions; the damage mechanics of porous rock; nonlinear attenuation mechanism in salt at moderate strain; compressional- and shear-wave polarizations at the Anza seismic array; and a generalized beamforming approach to real time network detection and phase association.

Multivariate Formation Pressure Prediction with Seismic-derived Petrophysical Properties from Prestack AVO inversion and Poststack Seismic Motion Inversion

NASA Astrophysics Data System (ADS)

Yu, H.; Gu, H.

2017-12-01

A novel multivariate seismic formation pressure prediction methodology is presented, which incorporates high-resolution seismic velocity data from prestack AVO inversion, and petrophysical data (porosity and shale volume) derived from poststack seismic motion inversion. In contrast to traditional seismic formation prediction methods, the proposed methodology is based on a multivariate pressure prediction model and utilizes a trace-by-trace multivariate regression analysis on seismic-derived petrophysical properties to calibrate model parameters in order to make accurate predictions with higher resolution in both vertical and lateral directions. With prestack time migration velocity as initial velocity model, an AVO inversion was first applied to prestack dataset to obtain high-resolution seismic velocity with higher frequency that is to be used as the velocity input for seismic pressure prediction, and the density dataset to calculate accurate Overburden Pressure (OBP). Seismic Motion Inversion (SMI) is an inversion technique based on Markov Chain Monte Carlo simulation. Both structural variability and similarity of seismic waveform are used to incorporate well log data to characterize the variability of the property to be obtained. In this research, porosity and shale volume are first interpreted on well logs, and then combined with poststack seismic data using SMI to build porosity and shale volume datasets for seismic pressure prediction. A multivariate effective stress model is used to convert velocity, porosity and shale volume datasets to effective stress. After a thorough study of the regional stratigraphic and sedimentary characteristics, a regional normally compacted interval model is built, and then the coefficients in the multivariate prediction model are determined in a trace-by-trace multivariate regression analysis on the petrophysical data. The coefficients are used to convert velocity, porosity and shale volume datasets to effective stress and then

Investigation of the seismic resistance of interior building partitions, phase 1

NASA Astrophysics Data System (ADS)

Anderson, R. W.; Yee, Y. C.; Savulian, G.; Barclay, B.; Lee, G.

1981-02-01

The effective participation of wood-framed interior shear wall partitions when determining the ultimate resistance capacity of two- and three-story masonry apartment buildings to seismic loading was investigated. Load vs. deflection tests were performed on 8 ft by 8 ft wall panel specimens constructed of four different facing materials, including wood lath and plaster, gypsum lath and plaster, and gypsum wallboard with joints placed either horizontally or vertically. The wood lath and plaster construction is found to be significantly stronger and stiffer than the other three specimens. Analyses of the test panels using finite element methods to predict their static resistance characteristics indicates that the facing material acts as the primary shear-resisting structural element. Resistance of shear wall partitions to lateral loads was assessed.

Map showing seismicity and sandblows in the vicinity of New Madrid, Missouri

USGS Publications Warehouse

Rhea, B. Susan; Tarr, Arthur C.; Wheeler, Russell L.

1994-01-01

This is one of a series of five seismotectic maps of the seismically active New Madrid, Missouri, area (table 1; Wheeler and others, 1992). The map area centers near the sites of three great earthquakes that struck during the winter of 1811-12 (Fuller, 1912; Nuttli, 1973). These earthquakes and continuing subsequent seismicity rank the New Madrid area with Cherlevoix, Quebec, as the two most seismically active areas in North America east of the Rocky Mountains. The threat posed by New Madrid seismicity to the central United States makes the area the focus of many investigations (for examples, Heyl and McKeown, 1978; McKeown and Pakiser, 1982; Algemissen and Hopper, 1984; Hamilton and Johnston, 1990; Applied Technology Council, 1991; Johnston and others, 1992). The map area includes the most intense seismic activity in the New Madrid region. A seismotectic map shows some of the geologic and geophysical information needed to assess seismic hazard (Hadley and Devine, 1974; Pavoni, 1985). A previous seismotectonic map of the central Mississippi River valley (Heyl and McKeown, 1978) has had wide use for planning field surveys, as a base map for plotting data collected during single investigations, and for compiling a range of information. Since 1978 numcrous researchers have greatly advanced our knowledge of the geology and geophysics of the central Mississippi Valley. The New Madrid seismotectonic map folio updates approximately the south-central sixth of the central Mississippi Valley seismotectonic map of Heyl and McKeown (1978).

Deep Seismic Reflection Images of the Sumatra Seismic and Aseismic Gaps

NASA Astrophysics Data System (ADS)

Singh, S. C.; Hananto, N. D.; Chauhan, A.; Carton, H. D.; Midenet, S.; Djajadihardja, Y.

2009-12-01

The Sumatra subduction zone is seismically most active region on the Earth, and has been the site of three great earthquakes only in the last four years. The first of the series, the 2004 Boxing Day earthquake, broke 1300 km of the plate boundary and produced the devastating tsunami around the Indian Ocean. The second great earthquake occurred three months later in March 2005, about 150 km SE of the 2004 event. The Earth waited for three years, and then broke again in September 2007 at 1300 km SE of the 2004 event producing a twin earthquake of magnitudes of 8.5 and 7.9 at an interval of 12 hours, leaving a seismic gap of about 600 km between the second and third earthquake, the Sumatra Seismic Gap. Seismological and geodetic studies suggest that this gap is fully locked and may break any time. In order to study the seismic and tsunami risk in this locked region, a deep seismic reflection survey (Tsunami Investigation Deep Evaluation Seismic -TIDES) was carried out in May 2009 using the CGGVeritas vessel Geowave Champion towing a 15 long streamer, the longest ever used during a seismic survey, to image the nature of the subducting plate and associated features, including the seismogenic zone, from seafloor down to 50 km depth. A total of 1700 km of deep seismic reflection data were acquired. Three dip lines traverse the Sumatra subduction zone; one going through the Sumatra Seismic Gap, one crossing the region that broke during the 2007 great earthquake, and one going through the aseismic zone. These three dip profiles should provide insight about the locking mechanism and help us to understand why an earthquake occurs in one zone and not in aseismic zone. A strike-line was shot in the forearc basin connecting the locked zone with broken zone profiles, which should provide insight about barriers that might have stopped propagation of 2007 earthquake rupture further northward.

Experimental investigation of damage behavior of RC frame members including non-seismically designed columns

NASA Astrophysics Data System (ADS)

Chen, Linzhi; Lu, Xilin; Jiang, Huanjun; Zheng, Jianbo

2009-06-01

Reinforced concrete (RC) frame structures are one of the mostly common used structural systems, and their seismic performance is largely determined by the performance of columns and beams. This paper describes horizontal cyclic loading tests of ten column and three beam specimens, some of which were designed according to the current seismic design code and others were designed according to the early non-seismic Chinese design code, aiming at reporting the behavior of the damaged or collapsed RC frame strctures observed during the Wenchuan earthquake. The effects of axial load ratio, shear span ratio, and transverse and longitudinal reinforcement ratio on hysteresis behavior, ductility and damage progress were incorporated in the experimental study. Test results indicate that the non-seismically designed columns show premature shear failure, and yield larger maximum residual crack widths and more concrete spalling than the seismically designed columns. In addition, longitudinal steel reinforcement rebars were severely buckled. The axial load ratio and shear span ratio proved to be the most important factors affecting the ductility, crack opening width and closing ability, while the longitudinal reinforcement ratio had only a minor effect on column ductility, but exhibited more influence on beam ductility. Finally, the transverse reinforcement ratio did not influence the maximum residual crack width and closing ability of the seismically designed columns.

The effect of reservoir geometry, injection and production parameters and permeability structure on induced seismicity

NASA Astrophysics Data System (ADS)

Hosseini, S. M.; Goebel, T.; Aminzadeh, F.

2015-12-01

The recent increase in injection induced seismicity (IIS) in previously less seismically active regions highlighted a need for better mitigation strategies and physics-based models of induced seismicity. Previous models of pressure diffusion and fluid flow investigated the change in Coulomb stress as a result of induced pore-pressure perturbations (e.g. Zhang et al., 2013; Keranen et al., 2014; Hornbach et al., 2015; Segall and Lu, 2015). Here, we consider the additional effects of permeability structure, operational parameters and reservoir geometry. We numerically investigate the influence of net fluid injection volumes; linear, radial, and spherical reservoir geometry; as well as reservoir size. The latter can have a substantial effect on changes in Coulomb stress and subsequent induced seismicity. We report on results from two series of model runs, which explored pressure changes caused by wastewater disposal and water flooding. We observed that a typical water flooding operation that includes production wells and injectors has a lower probability of inducing seismicity. Our observations are in agreement with assessment by National Research Council report on induced seismicity (2012). We developed a third suite of models that investigate the effect of permeability structure on injection-induced seismicity. We examine two cases of wastewater disposal in proximity to active faults: 1) in Central Illinois Basin and 2) in central California. In both cases, we observed that the size of the reservoir, presence of faults, and permeability contrast relative to the host rock, strongly influences the pressure changes with distance and time. These pressure changes vary widely but can easily lead to fault instability and seismic activity at up to 10 km distance from the injection well. The results of this study may help to select safe injection sites and operational conditions in order to minimize injection induced seismicity hazard.

Investigation on the real-time prediction of ground motions using seismic records observed in deep boreholes

NASA Astrophysics Data System (ADS)

Miyakoshi, H.; Tsuno, S.

2013-12-01

The present method of the EEW system installed in the railway field of Japan predicts seismic ground motions based on the estimated earthquake information about epicentral distances and magnitudes using initial P-waves observed on the surface. In the case of local earthquakes beneath the Tokyo Metropolitan Area, however, a method to directly predict seismic ground motions using P-waves observed in deep boreholes could issue EEWs more simply and surely. Besides, a method to predict seismic ground motions, using S-waves observed in deep boreholes and S-wave velocity structures beneath seismic stations, could show planar distributions of ground motions for train operation control areas in the aftermath of earthquakes. This information is available to decide areas in which the emergency inspection of railway structures should be performed. To develop those two methods, we investigated relationships between peak amplitudes on the surface and those in deep boreholes, using seismic records of KiK-net stations in the Kanto Basin. In this study, we used earthquake accelerograms observed in boreholes whose depths are deeper than the top face of Pre-Neogene basement and those on the surface at 12 seismic stations of KiK-net. We selected 243 local earthquakes whose epicenters are located around the Kanto Region. Those JMA magnitudes are in the range from 4.5 to 7.0. We picked the on-set of P-waves and S-waves using a vertical component and two horizontal components, respectively. Peak amplitudes of P-waves and S-waves were obtained using vertical components and vector sums of two horizontal components, respectively. We estimated parameters which represent site amplification factors beneath seismic stations, using peak amplitudes of S-waves observed in the deep borehole and those on the surface, to minimize the residuals between calculations by the theoretical equation and observations. Correlation coefficients between calculations and observations are high values in the range

Seismic Tomography

NASA Astrophysics Data System (ADS)

Nowack, Robert L.; Li, Cuiping

The inversion of seismic travel-time data for radially varying media was initially investigated by Herglotz, Wiechert, and Bateman (the HWB method) in the early part of the 20th century [1]. Tomographic inversions for laterally varying media began in seismology starting in the 1970’s. This included early work by Aki, Christoffersson, and Husebye who developed an inversion technique for estimating lithospheric structure beneath a seismic array from distant earthquakes (the ACH method) [2]. Also, Alekseev and others in Russia performed early inversions of refraction data for laterally varying upper mantle structure [3]. Aki and Lee [4] developed an inversion technique using travel-time data from local earthquakes.

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

NASA Astrophysics Data System (ADS)

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.

Research and development support for the Center for Seismic Studies

NASA Astrophysics Data System (ADS)

Romney, C. F.; Huszar, L.; Frazier, G. A.

1984-07-01

Work during the second and third quarters of FY1984 continued to be focused on the development of the Center for Seismic Studies, and on planning and developments to prepare for a test of Seismic data exchange and event determination, as proposed by the group of Scientific Experts, UN Committee on Disarmament. A help system was designed and partially completed, and other aids for new users of the Center's data and facilities were developed. An introduction to Ingres was prepared, and new experimental data bases were installed.

Basic Research on Seismic and Infrasonic Monitoring of the European Arctic

DTIC Science & Technology

2010-09-01

efficient high-frequency seismic energy propagation characteristics of the Barents Sea area. Seismic and infrasound signals at ARCES have recently been...detected since June 2006 have been associated with infrasound detections at ARCES and at stations of the infrasound networks of Sweden, Finland, and...efficient generators of infrasound than the military munitions explosions at Hukkakero, the blasts occur throughout the year and so will sample a far

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

NASA Astrophysics Data System (ADS)

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

2016-04-01

is seismic moment density (Mo/m3) and V stim is stimulated rock volume (m3). Mopossible = D ∗ V stim(1) We applied this conceptual model to real microseismic data set from Basel EGS project where several induced seismicity with large magnitude occurred and brought constructive damage. Using the hypocenter location determined by the researcher of Tohoku Univ., Japan and moment magnitude estimated from Geothermal Explorers Ltd., operating company, we were able to estimate reasonable seismic moment density meaning that one representative parameter exists and can characterize seismic activity at Basel at each time step. With stimulated rock volume which was also inferred from microseismic information, we estimated possible seismic moment and assess the difference with observed value. Possible seismic moment significantly increased after shut-in when the seismic cloud (stimulated zone) mostly progressed, resulting that the difference with the observed cumulative seismic moment automatically became larger. This suggests that there is moderate seismic moment which will be released in near future. In next few hours, the largest event actually occurred. Therefore, our proposed model was successfully able to forecast occurrence of the large events. Furthermore, best forecast of maximum magnitude was Mw 3 level and the largest event was Mw 3.41, showing reasonable performance in terms of quantitative forecast in magnitude. Our attempt to assess the seismic activity from microseismic information was successful and it also suggested magnitude release can be correlate with the expansion of seismic cloud as the definition of possible seismic moment model indicates. This relationship has been observed in microseismic observational study and several previous study also suggested their correlation with stress released rock volume. Our model showed harmonic results with these studies and provide practical method having clear physical meaning to assess the seismic activity in real

Influence of High Energy Electromagnetic Pulses on the Dynamics of the Seismic Process Around the Bishkek Test Area (Central Asia)

NASA Astrophysics Data System (ADS)

Matcharashvili, Teimuraz N.; Chelidze, Tamaz L.; Zhukova, Natalia N.

2015-07-01

Investigation of dynamical features of the seismic process as well as the possible influence of different natural and man-made impacts on it remains one of the main interdisciplinary research challenges. The question of external influences (forcings) acquires new importance in the light of known facts on possible essential changes, which occur in the behavior of complex systems due to different relatively weak external impacts. Seismic processes in the complicated tectonic system are not an exclusion from this general rule. In the present research we continued the investigation of dynamical features of seismic activity in Central Asia around the Bishkek (Kyrgyzstan) test area, where strong electromagnetic (EM) soundings were performed in the 1980s. The unexpected result of these experiments was that they revealed the impact of strong electromagnetic discharges on the microseismic activity of investigated area. We used an earthquake catalogue of this area to investigate dynamical features of seismic activity in periods before, during, and after the mentioned man-made EM forcings. Different methods of modern time series analysis have been used, such as wavelet transformation, Hilbert Huang transformation, detrended fluctuation analysis, and recurrence quantification analysis. Namely, inter-event (waiting) time intervals, inter-earthquake distances and magnitude sequences, as well as time series of the number of daily occurring earthquakes have been analyzed. We concluded that man-made high-energy EM irradiation essentially affects dynamics of the seismic process in the investigated area in its temporal and spatial domains; namely, the extent of order in earthquake time and space distribution increase. At the same time, EM influence on the energetic distribution is not clear from the present analysis. It was also shown that the influence of EM impulses on dynamical features of seismicity differs in different areas of the examined territory around the test site. Clear

50 years of Global Seismic Observations

NASA Astrophysics Data System (ADS)

Anderson, K. R.; Butler, R.; Berger, J.; Davis, P.; Derr, J.; Gee, L.; Hutt, C. R.; Leith, W. S.; Park, J. J.

2007-12-01

Seismological recordings have been made on Earth for hundreds of years in some form or another, however, global monitoring of earthquakes only began in the 1890's when John Milne created 40 seismic observatories to measure the waves from these events. Shortly after the International Geophysical Year (IGY), a concerted effort was made to establish and maintain a more modern standardized seismic network on the global scale. In the early 1960's, the World-Wide Standardized Seismograph Network (WWSSN) was established through funding from the Advanced Research Projects Agency (ARPA) and was installed and maintained by the USGS's Albuquerque Seismological Laboratory (then a part of the US Coast and Geodetic Survey). This network of identical seismic instruments consisted of 120 stations in 60 countries. Although the network was motivated by nuclear test monitoring, the WWSSN facilitated numerous advances in observational seismology. From the IGY to the present, the network has been upgraded (High-Gain Long-Period Seismograph Network, Seismic Research Observatories, Digital WWSSN, Global Telemetered Seismograph Network, etc.) and expanded (International Deployment of Accelerometers, US National Seismic Network, China Digital Seismograph Network, Joint Seismic Project, etc.), bringing the modern day Global Seismographic Network (GSN) to a current state of approximately 150 stations. The GSN consists of state-of-the-art very broadband seismic transducers, continuous power and communications, and ancillary sensors including geodetic, geomagnetic, microbarographic, meteorological and other related instrumentation. Beyond the GSN, the system of global network observatories includes contributions from other international partners (e.g., GEOSCOPE, GEOFON, MEDNET, F-Net, CTBTO), forming an even larger backbone of permanent seismological observatories as a part of the International Federation of Digital Seismograph Networks. 50 years of seismic network operations have provided

Bayesian identification of multiple seismic change points and varying seismic rates caused by induced seismicity

NASA Astrophysics Data System (ADS)

Montoya-Noguera, Silvana; Wang, Yu

2017-04-01

The Central and Eastern United States (CEUS) has experienced an abnormal increase in seismic activity, which is believed to be related to anthropogenic activities. The U.S. Geological Survey has acknowledged this situation and developed the CEUS 2016 1 year seismic hazard model using the catalog of 2015 by assuming stationary seismicity in that period. However, due to the nonstationary nature of induced seismicity, it is essential to identify change points for accurate probabilistic seismic hazard analysis (PSHA). We present a Bayesian procedure to identify the most probable change points in seismicity and define their respective seismic rates. It uses prior distributions in agreement with conventional PSHA and updates them with recent data to identify seismicity changes. It can determine the change points in a regional scale and may incorporate different types of information in an objective manner. It is first successfully tested with simulated data, and then it is used to evaluate Oklahoma's regional seismicity.

Planning Tools For Seismic Risk Mitigation. Rules And Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Paoli, Rosa Grazia

2008-07-08

Recently, Italian urban planning research in the field of seismic risk mitigation are renewing. In particular, it promotes strategies that integrate urban rehabilitation and aseismic objectives, and also politicizes that are directed to revitalizes urban systems, coupling physical renewal and socio-economic development.In Italy the first law concerning planning for seismic mitigation dates back 1974, the law n. 64 'Regulation for buildings with particular rules for the seismic areas' where the rules for buildings in seismic areas concerning also the local hazard. This law, in fact, forced the municipalities to acquire, during the formation of the plans, a preventive opinion ofmore » compatibility between planning conditions and geomorphology conditions of the territory. From this date the conviction that the seismic risk must be considered inside the territorial planning especially in terms of strategies of mitigation has been strengthened.The town planners have started to take an interest in seismic risk in the [80]s when the Irpinia's earthquake took place. The researches developed after this earthquake have established that the principal cause of the collapse of buildings are due to from the wrong location of urban settlements (on slopes or crowns) After Irpinia's earthquake the first researches on seismic risk mitigation, in particular on the aspects related to the hazards and to the urban vulnerability were made.« less

Small aperture seismic arrays for studying planetary interiors and seismicity

NASA Astrophysics Data System (ADS)

Schmerr, N. C.; Lekic, V.; Fouch, M. J.; Panning, M. P.; Siegler, M.; Weber, R. C.

2017-12-01

Seismic arrays are a powerful tool for understanding the interior structure and seismicity across objects in the Solar System. Given the operational constraints of ground-based lander investigations, a small aperture seismic array can provide many of the benefits of a larger-scale network, but does not necessitate a global deployment of instrumentation. Here we define a small aperture array as a deployment of multiple seismometers, with a separation between instruments of 1-1000 meters. For example, small aperture seismic arrays have been deployed on the Moon during the Apollo program, the Active Seismic Experiments of Apollo 14 and 16, and the Lunar Seismic Profiling Experiment deployed by the Apollo 17 astronauts. Both were high frequency geophone arrays with spacing of 50 meters that provided information on the layering and velocity structure of the uppermost kilometer of the lunar crust. Ideally such arrays would consist of instruments that are 3-axis short period or broadband seismometers. The instruments must have a sampling rate and frequency range sensitivity capable of distinguishing between waves arriving at each station in the array. Both terrestrial analogs and the data retrieved from the Apollo arrays demonstrate the efficacy of this approach. Future opportunities exist for deployment of seismic arrays on Europa, asteroids, and other objects throughout the Solar System. Here we will present both observational data and 3-D synthetic modeling results that reveal the sensing requirements and the primary advantages of a small aperture seismic array over single station approach. For example, at the smallest apertures of < 1 m, we constrain that sampling rates must exceed 500 Hz and instrument sensitivity must extend to 100 Hz or greater. Such advantages include the improved ability to resolve the location of the sources near the array through detection of backazimuth and differential timing between stations, determination of the small-scale structure

Georgia-Armenia Transboarder seismicity studies

NASA Astrophysics Data System (ADS)

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

Spatial Temporal Analysis Of Mine-induced Seismicity

NASA Astrophysics Data System (ADS)

Fedotova, I. V.; Yunga, S. L.

The results of analysis of influence mine-induced seismicity on state of stress of a rock mass are represented. The spatial-temporal analysis of influence of mass explosions on rock massif deformation is carried out in the territory of a mine field Yukspor of a wing of the Joined Kirovsk mine JSC "Apatite". Estimation of influence of mass explosions on a massif were determined based firstly on the parameters of natural seismicic regime, and secondly taking into consideration change of seismic energy release. After long series of explosions variations in average number of seismic events was fixed. Is proved, that with increase of a volume of rocks, involved in a deforma- tion the released energy of seismic events, and characteristic intervals of time of their preparation are also varied. At the same time, the mechanism of destruction changes also: from destruction's, of a type shift - separation before destruction's, in a quasi- solid heterogeneous massif (in oxidized zones and zones of actuated faults). Analysis of a database seismicity of a massif from 1993 to 1999 years has confirmed, that the response of a massif on explosions is connected to stress-deformations state a mas- sif and parameters of a mining working. The analysis of spatial-temporal distribution of hypocenters of seismic events has allowed to allocate migration of fissile regions of destruction after mass explosions. The researches are executed at support of the Russian foundation for basic research, - projects 00-05-64758, 01-05-65340.

Manifestations Of Mine-induced Seismicity At Large-scale Mining Operations In Khibiny Massive

NASA Astrophysics Data System (ADS)

Fedotova, I. V.; Kozyrev, A. A.; Yunga, S. L.

The focal mechanisms of seismic events in the Khibiny massive and their interrelation with spent mining operations were investigated. As a result it is detected, that redistri- bution of stresses stipulated by structural features of a rock mass and ore technology, is the basic reason of origin of dynamic rock pressure manifestations. On the basis of the available plan tectonic disturbances of an investigated lease of a massif and anal- ysis of seismic activity, in view of events with the detected focal mechanism, some bands, various on a degree of potential seismic activity are chosen. For each band the calculations of mechanisms of rock bumps with separation of planes of adjustments with engaging of the geologic data are held. As a result of this analysis it is approved, that the basic forerunner of cracking of a separation at a roof fall of the cantilever of hanging wall (on decryption of focal mechanisms) is the reorientation of axes of prin- cipal stresses. And, at conducting coal-face works in a trailing side of ore deposits, at cracking a separation in the cantilever of hanging wall there are seismic events pre- dominantly to a fault type of the focal mechanism. In a massif of soils of the working excavation, located in limits, and under it, most typical focal mechanisms are mainly strike-slip and normal faults. The researches are executed at support of the Russian foundation for basic research, - projects 00-05-64758, 01-05-65340.

Induced seismicity and the potential for liability under U.S. law

NASA Astrophysics Data System (ADS)

Cypser, Darlene A.; Davis, Scott D.

1998-04-01

Research by seismologists over the past 30+ years has firmly established that some human activities induce seismicity. Sometimes induced seismicity causes injuries to people or property. The activities which induce seismicity generally involve extraction of energy, or natural resources, or the disposal of wastes. As the human population increases these extraction and disposal activities will increase in number of sites and intensity of effort as the demands become greater and the resources scarcer. With these increases the number and severity of damaging induced earthquakes is likely to increase. Induced seismicity may cause injuries by vibrations or by seismically induced ground failure. In either case compensation for injuries caused by induced seismicity should be paid for by the inducer. In the United States the inducer of damaging seismicity can be made to pay for the harm caused. Liability for damage caused by vibrations can be based on several legal theories: trespass, strict liability, negligence and nuisance. Our research revealed no cases in which an appellate court has upheld or rejected the application of tort liability to an induced earthquake situation. However, there are numerous analogous cases that support the application of these legal theories to induced seismicity. Vibrations or concussions due to blasting or heavy machinery are sometimes viewed as a `trespass' analogous to a physical invasion. In some states activities which induce earthquakes might be considered `abnormally dangerous' activities that require companies engaged in them to pay for injuries the quakes cause regardless of how careful the inducers were. In some circumstances, a court may find that an inducer was negligent in its site selection or in maintenance of the project. If induced seismicity interferes with the use or enjoyment of another's land, then the inducing activity may be a legal nuisance, even if the seismicity causes little physical damage. In most states of the

Seismic Velocity Measurements at Expanded Seismic Network Sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woolery, Edward W; Wang, Zhenming

2005-01-01

Structures at the Paducah Gaseous Diffusion Plant (PGDP), as well as at other locations in the northern Jackson Purchase of western Kentucky may be subjected to large far-field earthquake ground motions from the New Madrid seismic zone, as well as those from small and moderate-sized local events. The resultant ground motion a particular structure is exposed from such event will be a consequence of the earthquake magnitude, the structures' proximity to the event, and the dynamic and geometrical characteristics of the thick soils upon which they are, of necessity, constructed. This investigation evaluated the latter. Downhole and surface (i.e., refractionmore » and reflection) seismic velocity data were collected at the Kentucky Seismic and Strong-Motion Network expansion sites in the vicinity of the Paducah Gaseous Diffusion Plant (PGDP) to define the dynamic properties of the deep sediment overburden that can produce modifying effects on earthquake waves. These effects are manifested as modifications of the earthquake waves' amplitude, frequency, and duration. Each of these three ground motion manifestations is also fundamental to the assessment of secondary earthquake engineering hazards such as liquefaction.« less

Investigating Deep-Marine Sediment Waves in the Northern Gulf of Mexico Using 3D Seismic Data

NASA Astrophysics Data System (ADS)

Wang, Z.; Gani, M. R.

2016-12-01

Deep-water depositional elements have been studied for decades using outcrop, flume tank, sidescan sonar, and seismic data. Even though they have been well recognized by researchers, the improvements in the quality of 3D seismic data with increasingly larger dimension allow detailed analysis of deep-water depositional elements with new insights. This study focuses on the deep-marine sediment waves in the northern Gulf of Mexico. By interpreting a 3D seismic dataset covering 635 km2 at Mississippi Canyon and Viosca Knoll areas, large sediment waves, generated by sediment gravity flows, were mapped and analyzed with various seismic attributes. A succession of sediment waves, approximately 100 m in thickness, is observed on the marine slope that tapers out at the toe of the slope. The individual sediment wave exhibits up to 500 m in wavelength and up to 20 m in height. The wave crests oriented northeast-southwest are broadly aligned parallel to the regional slope-strike, indicating their sediment gravity flow origin. The crestlines are straight or slightly sinuous, with sinuosity increasing downslope. Their anti-dune patterns likely imply the presence of supercritical flows. The sediment waves have a retrogradational stacking pattern. Seismic amplitude maps of each sediment wave revealed that after depositing the majority of sheet-like sands on the upper slope, sediment gravity flows started to form large sediment waves on the lower slope. The steep and narrow upcurrent flanks of the sediment waves always display higher amplitudes than the gentle and wide downcurrent flanks, indicating that the sands were likely preferentially trapped along the upcurrent flanks, whereas the muds spread along the downcurrent flanks. The formation of sediment waves likely requires a moderate sand-mud ratio, as suggested by these observations: (1) absence of sediment waves on the upper slope where the sands were mainly deposited as unconfined sheets with a high sand-mud ratio; (2

Numerical investigation of the seismic detectability of carbonate thin beds in the Boom Clay formation

NASA Astrophysics Data System (ADS)

Carcione, José M.; Gei, Davide

2016-07-01

The present study evaluates the capacity of the Boom Clay as a host rock for disposal purposes, more precisely its seismic characterization, which may assess its long-term performance to store radioactive wastes. Although the formation is relatively uniform and homogeneous, there are embedded thin layers of septaria (carbonates) that may affect the integrity of the Boom Clay. Therefore, it is essential to locate these geobodies. The seismic data to characterize the Boom Clay has been acquired at the Kruibeke test site. The inversion, which allowed us to obtain the anisotropy parameters and seismic velocities of the clay, is complemented with further information such as log and laboratory data. The attenuation properties have been estimated from equivalent formations (having similar composition and seismic velocities). The inversion yields quite consistent results although the symmetry of the medium is unusual but physically possible, since the anisotropy parameter ɛ is negative. According to a time-domain calculation of the energy velocity at four frequency bands up to 900 Hz, velocity increases with frequency, a behaviour described by the Zener model. Then, we use this model to describe anisotropy and anelasticity that are implemented into the equation of motion to compute synthetic seismograms in the space-time domain. The technique is based on memory variables and the Fourier pseudospectral method. We have computed reflection coefficients of the septaria thin layer. At normal incidence, the P-wave coefficient vanishes at specific thicknesses of the layer and there is no conversion to the S wave. For example, calculations at 600 Hz show that for thicknesses of 1 m the septarium can be detected more easily since the amplitudes are higher (nearly 0.8). Converted PS waves have a high amplitude at large offsets (between 30° and 80°) and can be useful to identify the target on this basis. Moreover, we have investigated the effect of septaria embedded in the Boom

Enhancement of seismic monitoring in hydrocarbon reservoirs

NASA Astrophysics Data System (ADS)

Caffagni, Enrico; Bokelmann, Götz

2017-04-01

Hydraulic Fracturing (HF) is widely considered as one of the most significant enablers of the successful exploitation of hydrocarbons in North America. Massive usage of HF is currently adopted to increase the permeability in shale and tight-sand deep reservoirs, despite the economical downturn. The exploitation success is less due to the subsurface geology, but in technology that improves exploration, production, and decision-making. This includes monitoring of the reservoir, which is vital. Indeed, the general mindset in the industry is to keep enhancing seismic monitoring. It allows understanding and tracking processes in hydrocarbon reservoirs, which serves two purposes, a) to optimize recovery, and b) to help minimize environmental impact. This raises the question of how monitoring, and especially seismic techniques could be more efficient. There is a pressing demand from seismic service industry to evolve quickly and to meet the oil-gas industry's changing needs. Nonetheless, the innovative monitoring techniques, to achieve the purpose, must enhance the characterization or the visualization of a superior-quality images of the reservoir. We discuss recent applications of seismic monitoring in hydrocarbon reservoirs, detailing potential enhancement and eventual limitations. The aim is to test the validity of these seismic monitoring techniques, qualitatively discuss their potential application to energy fields that are not only limited to HF. Outcomes from our investigation may benefit operators and regulators in case of future massive HF applications in Europe, as well. This work is part of the FracRisk consortium (www.fracrisk.eu), funded by the Horizon2020 research programme, whose aims is to help minimize the environmental footprint of the shale-gas exploration and exploitation.

Seismic retrofit workshop

DOT National Transportation Integrated Search

2006-11-01

Metallic dampers were proposed for the seismic retrofit of deficient highway bridges by the University of Missouri-Rolla (UMR) under the sponsorship of Missouri Department of Transportation (MODOT). A research project (MODOT Study No. RI 01-028) on t...

Numerical Investigations On The Seismic Behaviour Of Confined Masonry Walls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calderini, Chiara; Cattari, Serena; Lagomarsino, Sergio

2008-07-08

In the last century, severe earthquakes highlighted the seismic vulnerability of unreinforced masonry buildings. Many technological innovations have been introduced in time in order to improve resistance, ductility, and dissipation properties of this type of constructions. The most widely diffused are reinforced masonry and confined masonry. Damage observation of recent earthquakes demonstrated the effectiveness of the response of confined masonry structures to seismic actions. In general, in this type of structures, reinforced concrete beams and columns are not main structural elements, however, they have the following functions: to confine masonry in order to increase its ductility; to bear tensile stressesmore » derived from bending; to contrast the out-of-plane overturning of masonry panels. It is well evident that these functions are as much effectively performed as the connection between masonry and reinforced concrete elements is good (for example by mean of local interlocking or reinforcements). Confined masonry structures have been extensively studied in the last decades both from a theoretical point of view and by experimental tests Aims of this paper is to give a contribution to the understanding of the seismic behaviour of confined masonry walls by means of numerical parametrical analyses. There latter are performed by mean of the finite element method; a nonlinear anisotropic constitutive law recently developed for masonry is adopted. Comparison with available experimental results are carried out in order to validate the results. A comparison between the resistance obtained from the numerical analyses and the prevision provided by simplified resistance criteria proposed in literature and in codes is finally provided.« less

Seismic local site effects characterization in the Andarax River Valley (SE Spain) from ambient seismic noise

NASA Astrophysics Data System (ADS)

Carmona, Enrique; García-Jerez, Antonio; Luzón, Francisco; Sánchez-Martos, Francisco; Sánchez-Sesma, Francisco J.; Piña, José

2014-05-01

This work is focused on the characterization of seismic local effects in the Low Andarax River Valley (SE Spain). The Low Andarax River valley is located in an active seismic region, with the higher seismic hazard values in Spain. The landform is composed mainly by sedimentary materials which increase its seismic hazard due to the amplification of the seismic inputs and spectral resonances. We study seismic local effects in the Low Andarax River by analyzing the Horizontal-to-Vertical Spectral Ratio (HVSR) of ambient noise records. The noise data were recorded during two field campaigns in 2012 and 2013. There have been a total of 374 noise measurements with 15 and 30 minutes duration. The acquisition was performed with a Digital Broadband Seismometer Guralp CMG-6TD. The distance between measurements was about 200 meters, covering an area around 40 km2. There have been 6 significant peak frequencies between 0.3 Hz and 5 Hz. It was possible to find interesting areas with similar spectral peaks that coincide with zones with similar microgravimetric anomalies at the alluvial valley. It is also observed a decrease in the frequency peaks from West to East suggesting increased sediment layer. We also compute the soil models at those sites where geotechnical information is available, assuming that the seismic noise is diffuse. We invert the HVSR for these places using horizontally layered models and in the imaginary part the Green functions at the source. It is observed that the S wave velocity inverted models are consistent with the known geotechnical information obtained from drilled boreholes. We identify the elastodynamic properties of the limestone-dolomite materials with a formation of phyllites and quartzite that form the basement of the depression, and those properties of the Miocene and Pliocene detrital deposits (marls, sandy silts, sands and conglomerates) that fill the valley. These results together with the observed resonant frequencies along the Andarax

The deep Algerian margin structure revisited by the Algerian-French SPIRAL research program, stage 2 : Wide-ange seismic experiment

NASA Astrophysics Data System (ADS)

Klingelhoefer, Frauke; Yellès, Abdelkarim; Bracène, Rabah; Graindorge, David; Ouabadi, Aziouz; Schnürle, Philippe; Scientific Party, Spiral

2010-05-01

During the second leg of the Algerien - French SPIRAL (Sismique Profonde et Investigation Regionale du Nord de l'ALgerie) cruise conducted on the R/V Atalante in October and November 2009 an extensive wide-angle seismic data-set was acquired on 5 regional transects off Algeria, from Arzew bay to the west, to Annaba to the east. The profiles are between 80 and 180 km in length and around 40 ocean-bottom seismometers were deployed on each profile. A 8350 cu. inch tuned airgun array consisting of 10 Bolt airguns was used to generate of deep frequency to allow for a good penetration. All profiles were extended on land up to 150 km by land-stations to better constrain the structure of the margin and the nature of the ocean-continent transition zone. Coincident reflection seismic, gravity and magnetic data were acquired on all profiles during the first leg of the cruise. The resulting data quality is very good with deep penetrating arrivals on most of the instruments. Only on very few instruments a deep salt layer inhibits deeper penetration of the seismic energy. Two instruments were lost and all other yielded useful information on geophone and hydrophone channels. Instruments located close to the coast show arrivals from thick sedimentary layers. Instruments located on oceanic crust indicate a relatively thin crust overlying a mantle layer characterised by seismic velocities of 8 km/s. Forward and inverse modelling of the wide-angle seismic data will help constrain the deep structure of the margin, the nature of the crust and might help to constrain possible existence of a detached slab in the upper mantle. Integration of the wide-angle seismic data with multichannel seismic, gravity and magnetic data will enable us to better understand the tectonic history and the structure of the Algerian margin.

Romanian Educational Seismic Network Project

NASA Astrophysics Data System (ADS)

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

Application of seismic-refraction techniques to hydrologic studies

USGS Publications Warehouse

Haeni, F.P.

1986-01-01

During the past 30 years, seismic-refraction methods have been used extensively in petroleum, mineral, and engineering investigations, and to some extent for hydrologic applications. Recent advances in equipment, sound sources, and computer interpretation techniques make seismic refraction a highly effective and economical means of obtaining subsurface data in hydrologic studies. Aquifers that can be defined by one or more high seismic-velocity surfaces, such as (1) alluvial or glacial deposits in consolidated rock valleys, (2) limestone or sandstone underlain by metamorphic or igneous rock, or (3) saturated unconsolidated deposits overlain by unsaturated unconsolidated deposits,are ideally suited for applying seismic-refraction methods. These methods allow the economical collection of subsurface data, provide the basis for more efficient collection of data by test drilling or aquifer tests, and result in improved hydrologic studies.This manual briefly reviews the basics of seismic-refraction theory and principles. It emphasizes the use of this technique in hydrologic investigations and describes the planning, equipment, field procedures, and intrepretation techniques needed for this type of study.Examples of the use of seismic-refraction techniques in a wide variety of hydrologic studies are presented.

Application of seismic-refraction techniques to hydrologic studies

USGS Publications Warehouse

Haeni, F.P.

1988-01-01

During the past 30 years, seismic-refraction methods have been used extensively in petroleum, mineral, and engineering investigations and to some extent for hydrologic applications. Recent advances in equipment, sound sources, and computer interpretation techniques make seismic refraction a highly effective and economical means of obtaining subsurface data in hydrologic studies. Aquifers that can be defined by one or more high-seismic-velocity surface, such as (1) alluvial or glacial deposits in consolidated rock valleys, (2) limestone or sandstone underlain by metamorphic or igneous rock, or (3) saturated unconsolidated deposits overlain by unsaturated unconsolidated deposits, are ideally suited for seismic-refraction methods. These methods allow economical collection of subsurface data, provide the basis for more efficient collection of data by test drilling or aquifer tests, and result in improved hydrologic studies. This manual briefly reviews the basics of seismic-refraction theory and principles. It emphasizes the use of these techniques in hydrologic investigations and describes the planning, equipment, field procedures, and interpretation techniques needed for this type of study. Further-more, examples of the use of seismic-refraction techniques in a wide variety of hydrologic studies are presented.

Comparison of smoothing methods for the development of a smoothed seismicity model for Alaska and the implications for seismic hazard

NASA Astrophysics Data System (ADS)

Moschetti, M. P.; Mueller, C. S.; Boyd, O. S.; Petersen, M. D.

2013-12-01

In anticipation of the update of the Alaska seismic hazard maps (ASHMs) by the U. S. Geological Survey, we report progress on the comparison of smoothed seismicity models developed using fixed and adaptive smoothing algorithms, and investigate the sensitivity of seismic hazard to the models. While fault-based sources, such as those for great earthquakes in the Alaska-Aleutian subduction zone and for the ~10 shallow crustal faults within Alaska, dominate the seismic hazard estimates for locations near to the sources, smoothed seismicity rates make important contributions to seismic hazard away from fault-based sources and where knowledge of recurrence and magnitude is not sufficient for use in hazard studies. Recent developments in adaptive smoothing methods and statistical tests for evaluating and comparing rate models prompt us to investigate the appropriateness of adaptive smoothing for the ASHMs. We develop smoothed seismicity models for Alaska using fixed and adaptive smoothing methods and compare the resulting models by calculating and evaluating the joint likelihood test. We use the earthquake catalog, and associated completeness levels, developed for the 2007 ASHM to produce fixed-bandwidth-smoothed models with smoothing distances varying from 10 to 100 km and adaptively smoothed models. Adaptive smoothing follows the method of Helmstetter et al. and defines a unique smoothing distance for each earthquake epicenter from the distance to the nth nearest neighbor. The consequence of the adaptive smoothing methods is to reduce smoothing distances, causing locally increased seismicity rates, where seismicity rates are high and to increase smoothing distances where seismicity is sparse. We follow guidance from previous studies to optimize the neighbor number (n-value) by comparing model likelihood values, which estimate the likelihood that the observed earthquake epicenters from the recent catalog are derived from the smoothed rate models. We compare likelihood

Comparison of smoothing methods for the development of a smoothed seismicity model for Alaska and the implications for seismic hazard

USGS Publications Warehouse

Moschetti, Morgan P.; Mueller, Charles S.; Boyd, Oliver S.; Petersen, Mark D.

2014-01-01

In anticipation of the update of the Alaska seismic hazard maps (ASHMs) by the U. S. Geological Survey, we report progress on the comparison of smoothed seismicity models developed using fixed and adaptive smoothing algorithms, and investigate the sensitivity of seismic hazard to the models. While fault-based sources, such as those for great earthquakes in the Alaska-Aleutian subduction zone and for the ~10 shallow crustal faults within Alaska, dominate the seismic hazard estimates for locations near to the sources, smoothed seismicity rates make important contributions to seismic hazard away from fault-based sources and where knowledge of recurrence and magnitude is not sufficient for use in hazard studies. Recent developments in adaptive smoothing methods and statistical tests for evaluating and comparing rate models prompt us to investigate the appropriateness of adaptive smoothing for the ASHMs. We develop smoothed seismicity models for Alaska using fixed and adaptive smoothing methods and compare the resulting models by calculating and evaluating the joint likelihood test. We use the earthquake catalog, and associated completeness levels, developed for the 2007 ASHM to produce fixed-bandwidth-smoothed models with smoothing distances varying from 10 to 100 km and adaptively smoothed models. Adaptive smoothing follows the method of Helmstetter et al. and defines a unique smoothing distance for each earthquake epicenter from the distance to the nth nearest neighbor. The consequence of the adaptive smoothing methods is to reduce smoothing distances, causing locally increased seismicity rates, where seismicity rates are high and to increase smoothing distances where seismicity is sparse. We follow guidance from previous studies to optimize the neighbor number (n-value) by comparing model likelihood values, which estimate the likelihood that the observed earthquake epicenters from the recent catalog are derived from the smoothed rate models. We compare likelihood

Multiparametric statistical investigation of seismicity occurred at El Hierro (Canary Islands) from 2011 to 2014

NASA Astrophysics Data System (ADS)

Telesca, Luciano; Lovallo, Michele; Lopez, Carmen; Marti Molist, Joan

2016-03-01

A detailed statistical investigation of the seismicity occurred at El Hierro volcano (Canary Islands) from 2011 to 2014 has been performed by analysing the time variation of four parameters: the Gutenberg-Richter b-value, the local coefficient of variation, the scaling exponent of the magnitude distribution and the main periodicity of the earthquake sequence calculated by using the Schuster's test. These four parameters are good descriptors of the time and magnitude distributions of the seismic sequence, and their variation indicate dynamical changes in the volcanic system. These variations can be attributed to the causes and types of seismicity, thus allowing to distinguish between different host-rock fracturing processes caused by intrusions of magma at different depths and overpressures. The statistical patterns observed among the studied unrest episodes and between them and the eruptive episode of 2011-2012 indicate that the response of the host rock to the deformation imposed by magma intrusion did not differ significantly from one episode to the other, thus suggesting that no significant local stress changes induced by magma intrusion occurred when comparing between all them. Therefore, despite the studied unrest episodes were caused by intrusions of magma at different depths and locations below El Hierro island, the mechanical response of the lithosphere was similar in all cases. This suggests that the reason why the first unrest culminated in an eruption while the other did not, may be related to the role of the regional/local tectonics acting at that moment, rather than to the forceful of magma intrusion.

4-D Visualization of Seismic and Geodetic Data of the Big Island of Hawai'i

NASA Astrophysics Data System (ADS)

Burstein, J. A.; Smith-Konter, B. R.; Aryal, A.

2017-12-01

For decades Hawai'i has served as a natural laboratory for studying complex interactions between magmatic and seismic processes. Investigating characteristics of these processes, as well as the crustal response to major Hawaiian earthquakes, requires a synthesis of seismic and geodetic data and models. Here, we present a 4-D visualization of the Big Island of Hawai'i that investigates geospatial and temporal relationships of seismicity, seismic velocity structure, and GPS crustal motions to known volcanic and seismically active features. Using the QPS Fledermaus visualization package, we compile 90 m resolution topographic data from NASA's Shuttle Radar Topography Mission (SRTM) and 50 m resolution bathymetric data from the Hawaiian Mapping Research Group (HMRG) with a high-precision earthquake catalog of more than 130,000 events from 1992-2009 [Matoza et al., 2013] and a 3-D seismic velocity model of Hawai'i [Lin et al., 2014] based on seismic data from the Hawaiian Volcano Observatory (HVO). Long-term crustal motion vectors are integrated into the visualization from HVO GPS time-series data. These interactive data sets reveal well-defined seismic structure near the summit areas of Mauna Loa and Kilauea volcanoes, where high Vp and high Vp/Vs anomalies at 5-12 km depth, as well as clusters of low magnitude (M < 3.5) seismicity, are observed. These areas of high Vp and high Vp/Vs are interpreted as mafic dike complexes and the surrounding seismic clusters are associated with shallow magma processes. GPS data are also used to help identify seismic clusters associated with the steady crustal detachment of the south flank of Kilauea's East Rift Zone. We also investigate the fault geometry of the 2006 M6.7 Kiholo Bay earthquake event by analyzing elastic dislocation deformation modeling results [Okada, 1985] and HVO GPS and seismic data of this event. We demonstrate the 3-D fault mechanisms of the Kiholo Bay main shock as a combination of strike-slip and dip

Seismic performance for vertical geometric irregularity frame structures

NASA Astrophysics Data System (ADS)

Ismail, R.; Mahmud, N. A.; Ishak, I. S.

2018-04-01

This research highlights the result of vertical geometric irregularity frame structures. The aid of finite element analysis software, LUSAS was used to analyse seismic performance by focusing particularly on type of irregular frame on the differences in height floors and continued in the middle of the building. Malaysia’s building structures were affected once the earthquake took place in the neighbouring country such as Indonesia (Sumatera Island). In Malaysia, concrete is widely used in building construction and limited tension resistance to prevent it. Analysing structural behavior with horizontal and vertical static load is commonly analyses by using the Plane Frame Analysis. The case study of this research is to determine the stress and displacement in the seismic response under this type of irregular frame structures. This study is based on seven-storey building of Clinical Training Centre located in Sungai Buloh, Selayang, Selangor. Since the largest earthquake occurs in Acheh, Indonesia on December 26, 2004, the data was recorded and used in conducting this research. The result of stress and displacement using IMPlus seismic analysis in LUSAS Modeller Software under the seismic response of a formwork frame system states that the building is safe to withstand the ground and in good condition under the variation of seismic performance.

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

NASA Astrophysics Data System (ADS)

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).

Seismic experiment ross ice shelf 1990/91: Characteristics of the seismic reflection data

USGS Publications Warehouse

1993-01-01

The Transantarctic Mountains, with a length of 3000-3500 km and elevations of up to 4500 m, are one of the major Cenozoic mountain ranges in the world and are by far the most striking example of rift-shoulder mountains. Over the 1990-1991 austral summer Seismic Experiment Ross Ice Shelf (SERIS) was carried out across the Transantarctic Mountain front, between latitudes 82 degrees to 83 degrees S, in order to investigate the transition zone between the rifted area of the Ross Embayment and the uplifted Transantarctic Mountains. This experiment involved a 140 km long seismic reflection profile together with a 96 km long coincident wide-angle reflection/refraction profile. Gravity and relative elevation (using barometric pressure) were also measured along the profile. The primary purpose was to examine the boundary between the rift system and the uplifted rift margin (represented by the Transantarctic Mountains) using modern multi-channel crustal reflection/refraction techniques. The results provide insight into crustal structure across the plate boundary. SERIS also represented one of the first large-scale and modern multi-channel seismic experiments in the remote interior of Antarctica. As such, the project was designed to test different seismic acquisition techniques which will be involved in future seismic exploration of the continent. This report describes the results from the analysis of the acquisition tests as well as detailing some of the characteristics of the reflection seismic data. (auths.)

Seismic vulnerability of new highway construction, executive summary.

DOT National Transportation Integrated Search

2002-03-01

This executive summary gives an overview of the results of FHWA Contract DTFH61-92-C-00112, Seismic Research Program, : which performed a series of special studies addressing the seismic design of new construction. The objectives of this project : we...

Seismic Vulnerability of New Highway Construction, Executive Summary.

DOT National Transportation Integrated Search

2002-03-01

This executive summary gives an overview of the results of FHWA Contract DTFH61-92-C-00112, Seismic Research Program, which performed a series of special studies addressing the seismic design of new construction. The objectives of this project were t...

Seismic activity monitoring in the Izvorul Muntelui dam region

NASA Astrophysics Data System (ADS)

Borleanu, Felix; Otilia Placinta, Anca; Popa, Mihaela; Adelin Moldovan, Iren; Popescu, Emilia

2016-04-01

Earthquakes occurrences near the artificial water reservoirs are caused by stress variation due to the weight of water, weakness of fractures or faults and increasing of pore pressure in crustal rocks. In the present study we aim to investigate how Izvorul Muntelui dam, located in the Eastern Carpathians influences local seismicity. For this purpose we selected from the seismic bulletins computed within National Data Center of National Institute for Earth Physics, Romania, crustal events occurred between 984 and 2015 in a range of 0.3 deg around the artificial lake. Subsequently to improve the seismic monitoring of the region we applied a cross-correlation detector on the continuous recordings of Bicaz (BIZ) seismic stations. Besides the tectonic events we detected sources within this region that periodically generate artificial evens. We couldn't emphasize the existence of a direct correlation between the water level variations and natural seismicity of the investigated area.

Multi-sensor investigation of the Sumatran Tsunami: observations and analysis of hydroacoustic, seismic, infrasonic, and tide gauge data

NASA Astrophysics Data System (ADS)

Bhattacharyya, J.; Pulli, J.; Gibson, R.; Upton, Z.

2005-05-01

around the Indian Ocean to identify the arrival time of the Tsunami. The acoustic and seismic signals associated with the earthquakes arrive at the remote stations significantly ahead of the Tsunami. We combine the information from the various sensors to investigate the ability of the acoustic stations to detect the Tsunami.

Long Term Seismic Observation in Mariana by OBSs : Double Seismic Zone and Upper Mantle Structure

NASA Astrophysics Data System (ADS)

Shiobara, H.; Sugioka, H.; Mochizuki, K.; Oki, S.; Kanazawa, T.; Fukao, Y.; Suyehiro, K.

2005-12-01

In order to obtain the deep arc structural image of Mariana, a large-scale seismic observation by using 58 long-term ocean bottom seismometers (LTOBS) had been performed from June 2003 until April 2004, which is a part of the MARGINS program funded by the NSF. Prior to this observation, a pilot long-term seismic array observation was conducted in the same area by using 10 LTOBSs from Oct. 2001 until Feb. 2003. At that time, 8 LTOBSs were recovered but one had no data. Recently, 2 LTOBSs, had troubles in the releasing, were recovered by the manned submersible (Shinkai 6500, Jamstec) for the research of the malfunction in July 2005. By using all 9 LTOBS's data, those are about 11 months long, hypocenter determination was performed and more than 3000 local events were found. Even with the 1D velocity structure based on the iasp91 model, double seismic zones and a systematic shift of epicenters between the PDE and this study were observed. To investigate the detail of hypocenter distribution and the 3D velocity structure, the DD inversion (tomoDD: Zhang and Thurber, 2003) was applied for this data set with the 1D structure initial model except for the crust, which has been surveyed by using a dense airgun-OBS system (Takahashi et al., 2003). The result of relocated hypocenters shows clear double seismic zones until about 200 km depth, a high activity area around the fore-arc serpentine sea-mount, the Big Blue, and a lined focuses along the current ridge axis in the back-arc basin, and the result of the tomography shows a image of subducting slab and a low-Vs region below the same sea-mount mentioned. The wedge mantle structure was not clearly resolved due to the inadequate source-receiver coverage, which will be done in the recent experiment.

Global Seismic Cross-Correlation Results: Characterizing Repeating Seismic Events

NASA Astrophysics Data System (ADS)

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

2016-12-01

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

Seismic Investigation of the Glacier de la Plaine Morte, Switzerland

NASA Astrophysics Data System (ADS)

Laske, Gabi; Lindner, Fabian; Walter, Fabian; Krage, Manuel

2017-04-01

Glacier de la Plaine Morte is a plateau glacier along the border between Valais and Berne cantons. It covers a narrow elevation range and is extremely vulnerable to climate change. During snow melt, it feeds three marginal lakes that have experienced sudden subglacial drainage in recent years, thereby causing flooding in the Simme Valley below. Of greatest concern is Lac des Faverges at the southeastern end of the glacier that has drained near the end of July in recent years, with flood levels reaching capacity of flood control systems downstream. The lake levels are carefully monitored but precise prediction has not yet been achieved. In the search for precursory ice fracturing to the lake drainage to improve forecast, four seismic arrays comprised of five short-period borehole seismometers provided by Eidgenössische Technische Hochschule (ETH), Zürich as well as fifteen 3-component geophones from the Geophysical Instrument Pool Potsdam (GIPP) collected continuous seismic data for about seven weeks during the summer of 2016. We present initial results on discharge dynamics as well as changing noise levels and seismicity before, during and after the drainage of Lac des Faverges. Compared to previous recent years, the 2016 drainage of Lac des Faverges occurred unusually late on August 28. With an aperture between 100 and 200 m, the small arrays recorded many hundred ice quakes per day. A majority of the events exhibits clearly dispersed, high-frequency Rayleigh waves at about 10 Hz and higher. A wide distribution of events allows us to study azimuthal anisotropy and its relationship with the orientation of glacial crevasses.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

Injection induced seismicity (IIS) is an undesired dynamic rockmass response to massive fluid injections. This includes reactions, among others, to hydro-fracturing for shale gas exploitation. Complexity and changeability of technological factors that induce IIS, may result in significant deviations of the observed distributions of seismic process parameters from the models, which perform well in natural, tectonic seismic processes. Classic formulations of probabilistic seismic hazard analysis in natural seismicity assume the seismic marked point process to be a stationary Poisson process, whose marks - magnitudes are governed by a Gutenberg-Richter born exponential distribution. It is well known that the use of an inappropriate earthquake occurrence model and/or an inappropriate of magnitude distribution model leads to significant systematic errors of hazard estimates. It is therefore of paramount importance to check whether the mentioned, commonly used in natural seismicity assumptions on the seismic process, can be safely used in IIS hazard problems or not. Seismicity accompanying shale gas operations is widely studied in the framework of the project "Shale Gas Exploration and Exploitation Induced Risks" (SHEER). Here we present results of SHEER project investigations of such seismicity from Oklahoma and of a proxy of such seismicity - IIS data from The Geysers geothermal field. We attempt to answer to the following questions: • Do IIS earthquakes follow the Gutenberg-Richter distribution law, so that the magnitude distribution can be modelled by an exponential distribution? • Is the occurrence process of IIS earthquakes Poissonian? Is it segmentally Poissonian? If yes, how are these segments linked to cycles of technological operations? Statistical tests indicate that the Gutenberg-Richter relation born exponential distribution model for magnitude is, in general, inappropriate. The magnitude distribution can be complex, multimodal, with no ready

On-line Data Transmission, as Part of the Seismic Evaluation Process in the Buildings Field

NASA Astrophysics Data System (ADS)

Sorin Dragomir, Claudiu; Dobre, Daniela; Craifaleanu, Iolanda; Georgescu, Emil-Sever

2017-12-01

The thorough analytical modelling of seismic actions, of the structural system and of the foundation soil is essential for a proper dynamic analysis of a building. However, the validation of the used models should be made, whenever possible, with reference to results obtained from experimental investigations, building instrumentation and monitoring of vibrations generated by various seismic or non-seismic sources. In Romania, the permanent seismic instrumentation/monitoring of buildings is part of a special follow-up activity, performed in accordance with the P130/1999 code for the time monitoring of building behaviour and with the seismic design code, P100-2013. By using the state-of-the-art modern equipment (GeoSIG and Kinemetrics digital accelerographs) in the seismic network of the National Institute for Research and Development URBAN-INCERC, the instrumented buildings can be monitored remotely, with recorded data being sent to authorities or to research institutes in the field by a real-time data transmission system. The obtained records are processed, computing the Fourier amplitude spectra and the response spectra, and the modal parameters of buildings are determined. The paper presents some of the most important results of the institute in the field of building monitoring, focusing on the situation of some significant instrumented buildings located in different parts of the country. In addition, maps with data received from seismic stations after the occurrence of two recent Vrancea (Romania) earthquakes, showing the spatial distribution of ground accelerations, are presented, together with a comparative analysis, performed with reference to previous studies in the literature.

Martian seismicity

NASA Technical Reports Server (NTRS)

Phillips, Roger J.; Grimm, Robert E.

1991-01-01

The design and ultimate success of network seismology experiments on Mars depends on the present level of Martian seismicity. Volcanic and tectonic landforms observed from imaging experiments show that Mars must have been a seismically active planet in the past and there is no reason to discount the notion that Mars is seismically active today but at a lower level of activity. Models are explored for present day Mars seismicity. Depending on the sensitivity and geometry of a seismic network and the attenuation and scattering properties of the interior, it appears that a reasonable number of Martian seismic events would be detected over the period of a decade. The thermoelastic cooling mechanism as estimated is surely a lower bound, and a more refined estimate would take into account specifically the regional cooling of Tharsis and lead to a higher frequency of seismic events.

Updated Colombian Seismic Hazard Map

NASA Astrophysics Data System (ADS)

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

2013-05-01

possible to determinate environments and scenarios where the seismic hazard is a function of distance and magnitude and also the principal seismic sources that contribute to the seismic hazard at each site (dissagregation). This project was conducted by the Servicio Geológico Colombiano (Colombian Geological Survey) and the Universidad Nacional de Colombia (National University of Colombia), with the collaboration of national and foreign experts and the National System of Prevention and Attention of Disaster (SNPAD). It is important to stand out that this new seismic hazard map was used in the updated national building code (NSR-10). A new process is ongoing in order to improve and present the Seismic Hazard Map in terms of intensity. This require new knowledge in site effects, in both local and regional scales, checking the existing and develop new acceleration to intensity relationships, in order to obtain results more understandable and useful for a wider range of users, not only in the engineering field, but also all the risk assessment and management institutions, research and general community.

Tunnel Detection Using Seismic Methods

NASA Astrophysics Data System (ADS)

Miller, R.; Park, C. B.; Xia, J.; Ivanov, J.; Steeples, D. W.; Ryden, N.; Ballard, R. F.; Llopis, J. L.; Anderson, T. S.; Moran, M. L.; Ketcham, S. A.

2006-05-01

Surface seismic methods have shown great promise for use in detecting clandestine tunnels in areas where unauthorized movement beneath secure boundaries have been or are a matter of concern for authorities. Unauthorized infiltration beneath national borders and into or out of secure facilities is possible at many sites by tunneling. Developments in acquisition, processing, and analysis techniques using multi-channel seismic imaging have opened the door to a vast number of near-surface applications including anomaly detection and delineation, specifically tunnels. Body waves have great potential based on modeling and very preliminary empirical studies trying to capitalize on diffracted energy. A primary limitation of all seismic energy is the natural attenuation of high-frequency energy by earth materials and the difficulty in transmitting a high- amplitude source pulse with a broad spectrum above 500 Hz into the earth. Surface waves have shown great potential since the development of multi-channel analysis methods (e.g., MASW). Both shear-wave velocity and backscatter energy from surface waves have been shown through modeling and empirical studies to have great promise in detecting the presence of anomalies, such as tunnels. Success in developing and evaluating various seismic approaches for detecting tunnels relies on investigations at known tunnel locations, in a variety of geologic settings, employing a wide range of seismic methods, and targeting a range of uniquely different tunnel geometries, characteristics, and host lithologies. Body-wave research at the Moffat tunnels in Winter Park, Colorado, provided well-defined diffraction-looking events that correlated with the subsurface location of the tunnel complex. Natural voids related to karst have been studied in Kansas, Oklahoma, Alabama, and Florida using shear-wave velocity imaging techniques based on the MASW approach. Manmade tunnels, culverts, and crawl spaces have been the target of multi-modal analysis

Evaluation of seismic design spectrum based on UHS implementing fourth-generation seismic hazard maps of Canada

NASA Astrophysics Data System (ADS)

Ahmed, Ali; Hasan, Rafiq; Pekau, Oscar A.

2016-12-01

Two recent developments have come into the forefront with reference to updating the seismic design provisions for codes: (1) publication of new seismic hazard maps for Canada by the Geological Survey of Canada, and (2) emergence of the concept of new spectral format outdating the conventional standardized spectral format. The fourth -generation seismic hazard maps are based on enriched seismic data, enhanced knowledge of regional seismicity and improved seismic hazard modeling techniques. Therefore, the new maps are more accurate and need to incorporate into the Canadian Highway Bridge Design Code (CHBDC) for its next edition similar to its building counterpart National Building Code of Canada (NBCC). In fact, the code writers expressed similar intentions with comments in the commentary of CHBCD 2006. During the process of updating codes, NBCC, and AASHTO Guide Specifications for LRFD Seismic Bridge Design, American Association of State Highway and Transportation Officials, Washington (2009) lowered the probability level from 10 to 2% and 10 to 5%, respectively. This study has brought five sets of hazard maps corresponding to 2%, 5% and 10% probability of exceedance in 50 years developed by the GSC under investigation. To have a sound statistical inference, 389 Canadian cities are selected. This study shows the implications of the changes of new hazard maps on the design process (i.e., extent of magnification or reduction of the design forces).

Implied preference for seismic design level and earthquake insurance.

PubMed

Goda, K; Hong, H P

2008-04-01

Seismic risk can be reduced by implementing newly developed seismic provisions in design codes. Furthermore, financial protection or enhanced utility and happiness for stakeholders could be gained through the purchase of earthquake insurance. If this is not so, there would be no market for such insurance. However, perceived benefit associated with insurance is not universally shared by stakeholders partly due to their diverse risk attitudes. This study investigates the implied seismic design preference with insurance options for decisionmakers of bounded rationality whose preferences could be adequately represented by the cumulative prospect theory (CPT). The investigation is focused on assessing the sensitivity of the implied seismic design preference with insurance options to model parameters of the CPT and to fair and unfair insurance arrangements. Numerical results suggest that human cognitive limitation and risk perception can affect the implied seismic design preference by the CPT significantly. The mandatory purchase of fair insurance will lead the implied seismic design preference to the optimum design level that is dictated by the minimum expected lifecycle cost rule. Unfair insurance decreases the expected gain as well as its associated variability, which is preferred by risk-averse decisionmakers. The obtained results of the implied preference for the combination of the seismic design level and insurance option suggest that property owners, financial institutions, and municipalities can take advantage of affordable insurance to establish successful seismic risk management strategies.

Application of Neutral Networks to Seismic Signal Discrimination

DTIC Science & Technology

1993-05-15

AD-A276 626 PL-TR-93-2154 Application of Neural Networks to Seismic Signal Discrimination James A. Cercone V. Shane Foster W. Mike Clark Larry... Networks to Seismic Signal Discrimination PE 61101E PR 1DMO TA DA WU AA .AUTHOR(S) Stephen Goodman John Martin C James A. Cercone Don J. Smith G...of Technology Applications of Neural Networks to Seismic Classification project. The first year of research focused on identification and collection

Analytical Prediction of the Seismic Response of a Reinforced Concrete Containment Vessel

DOE Office of Scientific and Technical Information (OSTI.GOV)

James, R.J.; Rashid, Y.R.; Cherry, J.L.

Under the sponsorship of the Ministry of International Trade and Industry (MITI) of Japan, the Nuclear Power Engineering Corporation (NUPEC) is investigating the seismic behavior of a Reinforced Concrete Containment Vessel (RCCV) through scale-model testing using the high-performance shaking table at the Tadotsu Engineering Laboratory. A series of tests representing design-level seismic ground motions was initially conducted to gather valuable experimental measurements for use in design verification. Additional tests will be conducted with increasing amplifications of the seismic input until a structural failure of the test model occurs. In a cooperative program with NUPEC, the US Nuclear Regulatory Commission (USNRC),more » through Sandia National Laboratories (SNL), is conducting analytical research on the seismic behavior of RCCV structures. As part of this program, pretest analytical predictions of the model tests are being performed. The dynamic time-history analysis utilizes a highly detailed concrete constitutive model applied to a three-dimensional finite element representation of the test structure. This paper describes the details of the analysis model and provides analysis results.« less

Bayesian Inference for Signal-Based Seismic Monitoring

NASA Astrophysics Data System (ADS)

Moore, D.

2015-12-01

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

Bananas, Doughnuts and Seismic Traveltimes

NASA Astrophysics Data System (ADS)

Dahlen, F. A.

2002-12-01

Most of what we know about the 3-D seismic heterogeneity of the mantle is based upon ray-theoretical traveltime tomography. In this infinite-frequency approximation, a measured traveltime anomaly depends only upon the wavespeed along an infinitesimally thin geometrical ray between a seismic source and a seismographic station. In this lecture I shall describe a new formulation of the seismic traveltime inverse problem which accounts for the ability of a finite-frequency wave to ``feel'' 3-D structure off of the source-receiver ray. Finite-frequency diffraction effects associated with this off-ray sensitivity act to ``heal'' the corrugations that develop in a wavefront propagating through a heterogeneous medium. Ray-theoretical tomography is based upon the premise that a seismic wave ``remembers'' all of the traveltime advances or delays that it accrues along its path, whereas actual finite-frequency waves ``forget''. I shall describe a number of recent analytical and numerical investigations, which have led to an improved theoretical understanding of this phenomenon.

Automatic Seismic-Event Classification with Convolutional Neural Networks.

NASA Astrophysics Data System (ADS)

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

3D Seismic Experimentation and Advanced Processing/Inversion Development for Investigations of the Shallow Subsurface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levander, Alan Richard; Zelt, Colin A.

2015-03-17

The work plan for this project was to develop and apply advanced seismic reflection and wide-angle processing and inversion techniques to high resolution seismic data for the shallow subsurface to seismically characterize the shallow subsurface at hazardous waste sites as an aid to containment and cleanup activities. We proposed to continue work on seismic data that we had already acquired under a previous DoE grant, as well as to acquire additional new datasets for analysis. The project successfully developed and/or implemented the use of 3D reflection seismology algorithms, waveform tomography and finite-frequency tomography using compressional and shear waves for highmore » resolution characterization of the shallow subsurface at two waste sites. These two sites have markedly different near-surface structures, groundwater flow patterns, and hazardous waste problems. This is documented in the list of refereed documents, conference proceedings, and Rice graduate theses, listed below.« less

Uncertainty analysis in seismic tomography

NASA Astrophysics Data System (ADS)

Owoc, Bartosz; Majdański, Mariusz

2017-04-01

Velocity field from seismic travel time tomography depends on several factors like regularization, inversion path, model parameterization etc. The result also strongly depends on an initial velocity model and precision of travel times picking. In this research we test dependence on starting model in layered tomography and compare it with effect of picking precision. Moreover, in our analysis for manual travel times picking the uncertainty distribution is asymmetric. This effect is shifting the results toward faster velocities. For calculation we are using JIVE3D travel time tomographic code. We used data from geo-engineering and industrial scale investigations, which were collected by our team from IG PAS.

Co- and post-seismic shallow fault physics from near-field geodesy, seismic tomography, and mechanical modeling

NASA Astrophysics Data System (ADS)

Nevitt, J.; Brooks, B. A.; Catchings, R.; Goldman, M.; Criley, C.; Chan, J. H.; Glennie, C. L.; Ericksen, T. L.; Madugo, C. M.

2017-12-01

The physics governing near-surface fault slip and deformation are largely unknown, introducing significant uncertainty into seismic hazard models. Here we combine near-field measurements of surface deformation from the 2014 M6.0 South Napa earthquake with high-resolution seismic imaging and finite element models to investigate the effects of rupture speed, elastic heterogeneities, and plasticity on shallow faulting. We focus on two sites that experienced either predominantly co-seismic or post-seismic slip. We measured surface deformation with mobile laser scanning of deformed vine rows within 300 m of the fault at 1 week and 1 month after the event. Shear strain profiles for the co- and post-seismic sites are similar, with maxima of 0.012 and 0.013 and values exceeding 0.002 occurring within 26 m- and 18 m-wide zones, respectively. That the rupture remained buried at the two sites and produced similar deformation fields suggests that permanent deformation due to dynamic stresses did not differ significantly from the quasi-static case, which might be expected if the rupture decelerated as it approached the surface. Active-source seismic surveys, 120 m in length with 1 m geophone/shot spacing, reveal shallow compliant zones of reduced shear modulus. For the co- and post-seismic sites, the tomographic anomaly (Vp/Vs > 5) at 20 m depth has a width of 80 m and 50 m, respectively, much wider than the observed surface displacement fields. We investigate this discrepancy with a suite of finite element models in which a planar fault is buried 5 m below the surface. The model continuum is defined by either homogeneous or heterogeneous elastic properties, with or without Drucker-Prager plastic yielding, with properties derived from lab testing of similar near-surface materials. We find that plastic yielding can greatly narrow the surface displacement zone, but that the width of this zone is largely insensitive to changes in the elastic structure (i.e., the presence of a

Effects of Pre-existing Structures on the Seismicity of the Charlevoix Seismic Zone

NASA Astrophysics Data System (ADS)

Fadugba, O. I.; Choi, E.; Powell, C. A.

2017-12-01

The Charlevoix Seismic Zone (CSZ) occurs along the early Paleozoic St. Lawrence rift zone in southeastern Quebec at the location of a major Devonian impact crater. The crater superimposed major, steeply dipping basement faults trending N35°E. Many earthquakes are recorded each year in the CSZ and are concentrated within and beneath the impact crater. Some large-magnitude earthquakes associated with the rift faults occurred outside the crater. The primary goal of this research is to investigate combined effects of the pre-existing structures and regional stresses on earthquake activity in the CSZ. We set up some models using PyLith, an open-source finite-element code for simulations of crustal deformation. Our models will be compared with those of Baird et al. (2010), which took a different numerical approach for the same purpose of relating the regional structures, stresses, and seismicity. Adopting the results from recent hypocenter relocation study, we will modify the locations and dips of the rift faults and assess the effect of the new fault geometries on stress distributions. Finally, we will discuss whether modeled stress distributions can explain the seismicity distribution in the CSZ and published focal mechanism solutions. As a part of our efforts to enhance the reproducibility of these types of complex geodynamic models, selected models in this study will be made available in the form of sharable and reproducible packages. Such packaging is enabled by GeoTrust, an EarthCube-funded project that aims to automate the creation of a self-contained metadata package that provides a complete description of all data elements associated with a computational experiment.

Tutorial review of seismic surface waves' phenomenology

NASA Astrophysics Data System (ADS)

Levshin, A. L.; Barmin, M. P.; Ritzwoller, M. H.

2018-03-01

In recent years, surface wave seismology has become one of the leading directions in seismological investigations of the Earth's structure and seismic sources. Various applications cover a wide spectrum of goals, dealing with differences in sources of seismic excitation, penetration depths, frequency ranges, and interpretation techniques. Observed seismic data demonstrates the great variability of phenomenology which can produce difficulties in interpretation for beginners. This tutorial review is based on the many years' experience of authors in processing and interpretation of seismic surface wave observations and the lectures of one of the authors (ALL) at Workshops on Seismic Wave Excitation, Propagation and Interpretation held at the Abdus Salam International Center for Theoretical Physics (Trieste, Italy) in 1990-2012. We present some typical examples of wave patterns which could be encountered in different applications and which can serve as a guide to analysis of observed seismograms.

The experience of the Antarctic Seismic Data Library System (SDLS) as a hub for researchers in antarctic crustal studies.

NASA Astrophysics Data System (ADS)

Diviacco, Paolo; Wardell, Nigel

2010-05-01

The SDLS was created in April 1991 under the auspices of the Scientific Committee on Antarctic Research to provide open access to Antarctic multichannel seismic-reflection data (MCS) for use in cooperative research projects. The SDLS operates under the mandates of the Antarctic Treaty System, by which all institutions that collect MCS data in Antarctica must submit their MCS data to the SDLS. The SDLS has library branches worldwide at which researchers may view and study the MCS data. MCS data are submitted to the SDLS within 4 years of collection and remain in the library under SDLS guidelines until 8 years after collection. Thereafter, the data go to World Data Centers or equivalents for unrestricted use. The SDLS offers a clearing house, based at Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS) where data are processed when needed and georeferenced, so that the end user can be provided with usable, although basic, post-stack seismic sections. Re-processing of data is beyond the scope of the SDLS, so that if a researcher is interested in reviewing pre-stack data he/she must resort to the data owner. So far 228,000 km of seismic data have been made public in all sectors of the Antarctic region. To augment the concept of physical repositories where data can be accessed by researchers travelling to one of the branches or from where data could be copied to digital media and sent to users, in 2003 it was decided to develop a web interface where data could be searched for and accessed directly. At that moment no previous non-commercial experience was available in this data field, so that the system was designed from scratch. Several technologies were introduced, tested, and after a period of use, reviewed and tuned. Particular attention was devoted to the seismic data viewing facility, which was tailored to the needs of a community with specific practices and legacies. Seismic data are sensitive data that are very important for the E&P industry, so

Demonstration of improved seismic source inversion method of tele-seismic body wave

NASA Astrophysics Data System (ADS)

Yagi, Y.; Okuwaki, R.

2017-12-01

Seismic rupture inversion of tele-seismic body wave has been widely applied to studies of large earthquakes. In general, tele-seismic body wave contains information of overall rupture process of large earthquake, while the tele-seismic body wave is inappropriate for analyzing a detailed rupture process of M6 7 class earthquake. Recently, the quality and quantity of tele-seismic data and the inversion method has been greatly improved. Improved data and method enable us to study a detailed rupture process of M6 7 class earthquake even if we use only tele-seismic body wave. In this study, we demonstrate the ability of the improved data and method through analyses of the 2016 Rieti, Italy earthquake (Mw 6.2) and the 2016 Kumamoto, Japan earthquake (Mw 7.0) that have been well investigated by using the InSAR data set and the field observations. We assumed the rupture occurring on a single fault plane model inferred from the moment tensor solutions and the aftershock distribution. We constructed spatiotemporal discretized slip-rate functions with patches arranged as closely as possible. We performed inversions using several fault models and found that the spatiotemporal location of large slip-rate area was robust. In the 2016 Kumamoto, Japan earthquake, the slip-rate distribution shows that the rupture propagated to southwest during the first 5 s. At 5 s after the origin time, the main rupture started to propagate toward northeast. First episode and second episode correspond to rupture propagation along the Hinagu fault and the Futagawa fault, respectively. In the 2016 Rieti, Italy earthquake, the slip-rate distribution shows that the rupture propagated to up-dip direction during the first 2 s, and then rupture propagated toward northwest. From both analyses, we propose that the spatiotemporal slip-rate distribution estimated by improved inversion method of tele-seismic body wave has enough information to study a detailed rupture process of M6 7 class earthquake.

Statistical Seismology and Induced Seismicity

NASA Astrophysics Data System (ADS)

Tiampo, K. F.; González, P. J.; Kazemian, J.

2014-12-01

While seismicity triggered or induced by natural resources production such as mining or water impoundment in large dams has long been recognized, the recent increase in the unconventional production of oil and gas has been linked to rapid rise in seismicity in many places, including central North America (Ellsworth et al., 2012; Ellsworth, 2013). Worldwide, induced events of M~5 have occurred and, although rare, have resulted in both damage and public concern (Horton, 2012; Keranen et al., 2013). In addition, over the past twenty years, the increase in both number and coverage of seismic stations has resulted in an unprecedented ability to precisely record the magnitude and location of large numbers of small magnitude events. The increase in the number and type of seismic sequences available for detailed study has revealed differences in their statistics that previously difficult to quantify. For example, seismic swarms that produce significant numbers of foreshocks as well as aftershocks have been observed in different tectonic settings, including California, Iceland, and the East Pacific Rise (McGuire et al., 2005; Shearer, 2012; Kazemian et al., 2014). Similarly, smaller events have been observed prior to larger induced events in several occurrences from energy production. The field of statistical seismology has long focused on the question of triggering and the mechanisms responsible (Stein et al., 1992; Hill et al., 1993; Steacy et al., 2005; Parsons, 2005; Main et al., 2006). For example, in most cases the associated stress perturbations are much smaller than the earthquake stress drop, suggesting an inherent sensitivity to relatively small stress changes (Nalbant et al., 2005). Induced seismicity provides the opportunity to investigate triggering and, in particular, the differences between long- and short-range triggering. Here we investigate the statistics of induced seismicity sequences from around the world, including central North America and Spain, and

Introduction of digital object identifiers (DOI) for seismic networks

NASA Astrophysics Data System (ADS)

Evans, Peter; Strollo, Angelo; Clark, Adam; Ahern, Tim; Newman, Rob; Clinton, John; Pequegnat, Catherine; Pedersen, Helle

2015-04-01

Proper attribution for scientific source data is important in promoting transparency and recognising the role of data providers in science. Data sets such as those produced by seismic networks now need to be citable and permanently locatable for research users. Recently the EIDA and IRIS-DMC communities have worked together on development of methods for generation, maintenance and promotion of persistent identifiers for seismic networks. This resulted in a 2014 Recommendation by the International Federation of Digital Seismograph Networks (FDSN) on the use of Digital Object Identifiers (DOI) for seismic networks. These can be cited equivalently to scientific papers, and tools such as DataCite allow the tracking of citations to these datasets. The GEOFON, IRIS and RESIF data centres have now begun to roll-out of these seismic network DOIs. This has involved working with principal investigators to prepare metadata consistent with the FDSN recommendation, preparation of landing pages, and changes to the web sites to promote DOIs where available. This has involved preparing improved descriptions of the data (metadata) and clarifying how individuals and institutions should best be recognised for their contributions to making the data available. We illustrate this process for a few representative networks. We will be in contact with additional network operators to help them establish DOIs for their networks in future.

Two types of seismicity accompanying hydraulic fracturing in Harrison County, Ohio - implications for seismic hazard and seismogenic mechanism

NASA Astrophysics Data System (ADS)

Kozlowska, M.; Brudzinski, M.; Friberg, P. A.; Skoumal, R.; Baxter, N. D.; Currie, B.

2017-12-01

While induced seismicity in the United States has mainly been attributed to wastewater disposal, Eastern Ohio has provided cases of seismicity induced by both hydraulic fracturing (HF) and wastewater disposal. In this study, we investigate five cases of seismicity associated with HF in Harrison County, OH. Because of their temporal and spatial isolation from other injection activities, this provide an ideal setting for studying the relationships between high pressure injection and earthquakes. Our analysis reveals two distinct groups of seismicity. Deeper earthquakes occur in the Precambrian crystalline basement, reach larger magnitudes (M>2), have lower b-values (<1), and continue for weeks following stimulation shut down. Shallower earthquakes, on the other hand, occur in Paleozoic sedimentary rocks 400 m below HF, are limited to smaller magnitudes (M<1), have higher b-values (>1.5), and lack post-stimulation activity. We seek the physical explanation of observed difference in earthquakes character and hypothesize that the maturity of faults is the main factor determining sequences b-values. Based on published results of laboratory experiments and fault modeling, we interpret the deep seismicity as slip on more mature faults in the older crystalline rocks and the shallow seismicity as slip on immature faults in the younger, lower viscosity sedimentary rocks. This suggests that HF inducing seismicity on deeper, more mature faults poses higher seismic hazards. The analysis of water and gas production data from these wells suggests that wells inducing deeper seismicity produced more water than wells with shallow seismicity. This indicates more extensive hydrologic connections outside the target reservoir, which may explain why gas production drops more quickly for wells with deeper seismicity. Despite these indications that hydraulic pressure fluctuations induce seismicity, we also find only 2-3 hours between onset of stimulation of HF wells and seismicity that is

Seismic Source Scaling and Discrimination in Diverse Tectonic Environments

DTIC Science & Technology

2009-09-30

3349-3352. Imanishi, K., W. L. Ellsworth, and S. G. Prejean (2004). Earthquake source parameters determined by the SAFOD Pilot Hole seismic array ... seismic discrimination by performing a thorough investigation of* earthquake source scaling using diverse, high-quality datascts from varied tectonic...these corrections has a direct impact on our ability to identify clandestine explosions in the broad regional areas characterized by low seismicity

Multicomponent ensemble models to forecast induced seismicity

NASA Astrophysics Data System (ADS)

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

2018-01-01

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

Seismic activity in northeastern Brazill-new perspectives

NASA Astrophysics Data System (ADS)

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.

Seismic investigation of an ocean-continent transition zone in the northern South China Sea

NASA Astrophysics Data System (ADS)

Zhu, J.; Qiu, X.; Xu, H.; Zhan, W.; Sun, Z.

2011-12-01

Rifted continental margins and basins are mainly formed by the lithospheric extension. Thined lithosphere of passive continental margins results in decompression melt of magma and created oceanic crust and thined ocean-continent transition (OCT) zone. Two refraction profiles used ocean bottom seismometers deployed in the broad continental shelf and three multi-channel seismic reflection lines in the northern South China Sea, acquired by the ship "Shiyan 2" of the South China Sea Institute of Oceanology, Chinese Academy of Sciences in 2010, are processed and interpreted in this study. Seismic reflection lines cut through the Dongsha rise, Zhu-1 and Zhu-2 depression within a Tertiary basin, Pear River Mouth basin (called as Zhujiangkou basin). These tectonic features are clear imaged in the seismic reflection records. Numerous normal faults, cutted through the basement and related to the stretch of the northern South China Sea margin, are imaged and interpreted. Reflection characteristics of the ocean-continent transition (OCT) zone are summaried and outlined. The COT zone is mainly divided into the northern syn-rift subsidence zone, central volcano or buried volcano uplift zone and tilt faulted block near the South Chia Sea basin. Compared to the previous seismic reflection data and refraction velocity models, the segmentation range of the OCT zone is outlined, from width of about 225 km in the northeastern South China Sea , of 160 km in the central to of 110 km in the north-central South China Sea. Based on the epicenter distribution of sporadic and large than 6 magnitude earthquakes, it suggests the OCT zone in the northern South China Sea at present is still an active seismic zone.

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

NASA Astrophysics Data System (ADS)

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

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

Evaluation of the Seismic Hazard in Venezuela with a revised seismic catalog that seeks for harmonization along the country borders

NASA Astrophysics Data System (ADS)

Rendon, H.; Alvarado, L.; Paolini, M.; Olbrich, F.; González, J.; Ascanio, W.

2013-05-01

Probabilistic Seismic Hazard Assessment is a complex endeavor that relies on the quality of the information that comes from different sources: the seismic catalog, active faults parameters, strain rates, etc. Having this in mind, during the last several months, the FUNVISIS seismic hazard group has been working on a review and update of the local data base that form the basis for a reliable PSHA calculation. In particular, the seismic catalog, which provides the necessary information that allows the evaluation of the critical b-value, which controls how seismic occurrence distributes with magnitude, has received particular attention. The seismic catalog is the result of the effort of several generations of researchers along the years; therefore, the catalog necessarily suffers from the lack of consistency, homogeneity and completeness for all ranges of magnitude over any seismic study area. Merging the FUNVISIS instrumental catalog with the ones obtained from international agencies, we present the work that we have been doing to produce a consistent seismic catalog that covers Venezuela entirely, with seismic events starting from 1910 until 2012, and report the magnitude of completeness for the different periods. Also, we present preliminary results on the Seismic Hazard evaluation that takes into account such instrumental catalog, the historical catalog, updated known fault geometries and its correspondent parameters, and the new seismic sources that have been defined accordingly. Within the spirit of the Global Earthquake Model (GEM), all these efforts look for possible bridges with neighboring countries to establish consistent hazard maps across the borders.

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

NASA Astrophysics Data System (ADS)

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

2013-04-01

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

The Propagation of Seismic Waves in the Presence of Strong Elastic Property Contrasts

NASA Astrophysics Data System (ADS)

Saleh, R.; Jeyaraj, R.; Milkereit, B.; Liu, Q.; Valley, B.

2012-12-01

In an active underground mine there are many seismic activities taking place, such as seismic noises, blasts, tremors and microseismic events. In between the activities, the microseismic events are mainly used for monitoring purposes. The frequency content of microseismic events can be up to few KHz, which can result in wavelengths on the order of a few meters in hard rock environment. In an underground mine, considering the presence of both small wavelength and strong elastic contrasts, the simulation of seismic wave propagation is a challenge. With the recent availability of detailed 3D rock property models of mines, in addition to the development of efficient numerical techniques (such as Spectral Element Method (SEM)), and parallel computation facilities, a solution for such a problem is achievable. Most seismic wave scattering studies focus on large scales (>1 km) and weak elastic contrasts (velocity perturbations less than 10%). However, scattering in the presence of small-scale heterogeneities and large elastic contrasts is an area of ongoing research. In a mine environment, the presence of strong contrast discontinuities such as massive ore bodies, tunnels and infrastructure lead to discontinuities of displacement and/or stress tensor components, and have significant impact on the propagation of seismic waves. In order to obtain an accurate image of wave propagation in such a complex media, it is necessary to consider the presence of these discontinuities in numerical models. In this study, the effects of such a contrast are illustrated with 2D/3D modeling and compared with real broadband 3-component seismic data. The real broadband 3-component seismic data will be obtained in one of the Canadian underground mines in Ontario. One of the possible scenarios investigated in this study that may explain the observed complexity in seismic wavefield pattern in hard rock environments is the effect of near field displacements rather than far field. Considering the

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

NASA Astrophysics Data System (ADS)

Ramanathan, Karthik Narayan

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

Intensity Based Seismic Hazard Map of Republic of Macedonia

NASA Astrophysics Data System (ADS)

Dojcinovski, Dragi; Dimiskovska, Biserka; Stojmanovska, Marta

2016-04-01

The territory of the Republic of Macedonia and the border terrains are among the most seismically active parts of the Balkan Peninsula belonging to the Mediterranean-Trans-Asian seismic belt. The seismological data on the R. Macedonia from the past 16 centuries point to occurrence of very strong catastrophic earthquakes. The hypocenters of the occurred earthquakes are located above the Mohorovicic discontinuity, most frequently, at a depth of 10-20 km. Accurate short -term prognosis of earthquake occurrence, i.e., simultaneous prognosis of time, place and intensity of their occurrence is still not possible. The present methods of seismic zoning have advanced to such an extent that it is with a great probability that they enable efficient protection against earthquake effects. The seismic hazard maps of the Republic of Macedonia are the result of analysis and synthesis of data from seismological, seismotectonic and other corresponding investigations necessary for definition of the expected level of seismic hazard for certain time periods. These should be amended, from time to time, with new data and scientific knowledge. The elaboration of this map does not completely solve all issues related to earthquakes, but it provides basic empirical data necessary for updating the existing regulations for construction of engineering structures in seismically active areas regulated by legal regulations and technical norms whose constituent part is the seismic hazard map. The map has been elaborated based on complex seismological and geophysical investigations of the considered area and synthesis of the results from these investigations. There were two phases of elaboration of the map. In the first phase, the map of focal zones characterized by maximum magnitudes of possible earthquakes has been elaborated. In the second phase, the intensities of expected earthquakes have been computed according to the MCS scale. The map is prognostic, i.e., it provides assessment of the

The Salton Seismic Imaging Project: Seismic velocity structure of the Brawley Seismic Zone, Salton Buttes and Geothermal Field, Salton Trough, California

NASA Astrophysics Data System (ADS)

Delph, J.; Hole, J. A.; Fuis, G. S.; Stock, J. M.; Rymer, M. J.

2011-12-01

The Salton Trough is an active rift in southern California in a step-over between the plate-bounding Imperial and San Andreas Faults. In March 2011, the Salton Seismic Imaging Project (SSIP) investigated the rift's crustal structure by acquiring several seismic refraction and reflection lines. One of the densely sampled refraction lines crosses the northern-most Imperial Valley, perpendicular to the strike-slip faults and parallel to a line of small Quaternary rhyolitic volcanoes. The line crosses the obliquely extensional Brawley Seismic Zone and goes through one of the most geothermally productive areas in the United States. Well logs indicate the valley is filled by several kilometers of late Pliocene-recent lacustrine, fluvial, and shallow marine sediment. The 42-km long seismic line was comprised of eleven 110-460 kg explosive shots and receivers at a 100 m spacing. First arrival travel times were used to build a tomographic seismic velocity image of the upper crust. Velocity in the valley increases smoothly from <2 km/s to >5 km/s, indicating diagenesis and gradational metamorphism of rift sediments at very shallow depth due to an elevated geotherm. The velocity gradient is much smaller in the relatively low velocity (<6 km/s) crystalline basement comprised of recently metamorphosed sediment reaching greenschist to lower amphibolite facies. The depth of this basement is about 4-km below the aseismic region of the valley west of the Brawley Seismic Zone, but rises sharply to ~2 km depth beneath the seismically, geothermally, and volcanically active area of the Brawley Seismic Zone. The basement deepens to the northeast of the active tectonic zone and then is abruptly offset to shallower depth on the northeast side of the valley. This offset may be the subsurficial expression of a paleofault, most likely an extension of the Sand Hills Fault, which bounds the basin to the east. Basement velocity east of the fault is ~5.7 km/s, consistent with the granitic rocks

Instant Variations in Velocity and Attenuation of Seismic Waves in a Friable Medium Under a Vibrational Dynamic Loading

NASA Astrophysics Data System (ADS)

Geza, N.; Yushin, V.

2007-12-01

Instant variations of the velocities and attenuation of seismic waves in a friable medium subjected to dynamic loading have been studied by new experimental techniques using a powerful seismic vibrator. The half-space below the operating vibrator baseplate was scanned by high-frequency elastic waves, and the recorded fluctuations were exposed to a stroboscopic analysis. It was found that the variations of seismic velocities and attenuation are synchronous with the external vibrational load but have phase shift from it. Instant variations of the seismic waves parameters depend on the magnitude and absolute value of deformation, which generally result in decreasing of the elastic-wave velocities. New experimental techniques have a high sensitivity to the dynamic disturbance in the medium and allow one to detect a weak seismic boundaries. The relaxation process after dynamic vibrational loading were investigated and the results of research are presented.

Seismic Fragility Analysis of a Condensate Storage Tank with Age-Related Degradations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nie, J.; Braverman, J.; Hofmayer, C

2011-04-01

The Korea Atomic Energy Research Institute (KAERI) is conducting a five-year research project to develop a realistic seismic risk evaluation system which includes the consideration of aging of structures and components in nuclear power plants (NPPs). The KAERI research project includes three specific areas that are essential to seismic probabilistic risk assessment (PRA): (1) probabilistic seismic hazard analysis, (2) seismic fragility analysis including the effects of aging, and (3) a plant seismic risk analysis. Since 2007, Brookhaven National Laboratory (BNL) has entered into a collaboration agreement with KAERI to support its development of seismic capability evaluation technology for degraded structuresmore » and components. The collaborative research effort is intended to continue over a five year period. The goal of this collaboration endeavor is to assist KAERI to develop seismic fragility analysis methods that consider the potential effects of age-related degradation of structures, systems, and components (SSCs). The research results of this multi-year collaboration will be utilized as input to seismic PRAs. This report describes the research effort performed by BNL for the Year 4 scope of work. This report was developed as an update to the Year 3 report by incorporating a major supplement to the Year 3 fragility analysis. In the Year 4 research scope, an additional study was carried out to consider an additional degradation scenario, in which the three basic degradation scenarios, i.e., degraded tank shell, degraded anchor bolts, and cracked anchorage concrete, are combined in a non-perfect correlation manner. A representative operational water level is used for this effort. Building on the same CDFM procedure implemented for the Year 3 Tasks, a simulation method was applied using optimum Latin Hypercube samples to characterize the deterioration behavior of the fragility capacity as a function of age-related degradations. The results are summarized in

Seismic and tsunami hazard investigation in Valparaiso in the framework of the project "MAR VASTO"

NASA Astrophysics Data System (ADS)

Romanelli, F.; Razafindrakoto, H.

2009-04-01

In the framework of the MAR VASTO Project ("Risk Management in Valparaíso/Manejo de Riesgos en Valparaíso"), completed in 2008 and funded by BID/IDB (Banco InterAmericano de Desarrollo/ InterAmerican Development Bank), managed by ENEA (Italian Agency for New Technologies, Energy and Environment), with the participation of Italian and Chilean partners and the support of local stakeholders, the most important hazards have been investigated carried out. Valparaíso represents a distinctive case of growth, inside a remarkable landscape, of an important Pacific Ocean seaport (over the 19th and 20th centuries), up to reaching a strategic importance in shipping trade, declined after the Panama Canal opening (1914). Thus, Valparaíso tells the never-ending story of a tight interaction between society and environment, stratifying different urban and architectonic layers, sometimes struck by disasters and always in danger. Certainly, the city has been subjected to various natural hazards (seismic events, but also tsunamis, landslides, etc.) and anthropic calamities (mainly wild and human-induced fires). These features make Valparaíso a paradigmatic study case about hazard mitigation, and risk factors must be very well evaluated during the restoration phases to be planned in the future. Seismic Hazrad. The major goal is to provide a dataset of synthetic time series representative of the potential ground motion at the bedrock of Valparaiso, especially at selected sites (e.g. the three important churches located in the Valparaiso urban area: La Matriz, San Francisco, Las Hermanitas de la Providencia), for different scenarios; the characteristics of the calculated signals (e.g. amplitude, frequency content and duration of shaking) are determined by the earthquake source process and the wave propagation effects of the path between the source and the site. The synthetic signals, to be used as seismic input in a subsequent engineering analysis, have been produced at a very low

Earthquakes in Action: Incorporating Multimedia, Internet Resources, Large-scale Seismic Data, and 3-D Visualizations into Innovative Activities and Research Projects for Today's High School Students

NASA Astrophysics Data System (ADS)

Smith-Konter, B.; Jacobs, A.; Lawrence, K.; Kilb, D.

2006-12-01

The most effective means of communicating science to today's "high-tech" students is through the use of visually attractive and animated lessons, hands-on activities, and interactive Internet-based exercises. To address these needs, we have developed Earthquakes in Action, a summer high school enrichment course offered through the California State Summer School for Mathematics and Science (COSMOS) Program at the University of California, San Diego. The summer course consists of classroom lectures, lab experiments, and a final research project designed to foster geophysical innovations, technological inquiries, and effective scientific communication (http://topex.ucsd.edu/cosmos/earthquakes). Course content includes lessons on plate tectonics, seismic wave behavior, seismometer construction, fault characteristics, California seismicity, global seismic hazards, earthquake stress triggering, tsunami generation, and geodetic measurements of the Earth's crust. Students are introduced to these topics through lectures-made-fun using a range of multimedia, including computer animations, videos, and interactive 3-D visualizations. These lessons are further enforced through both hands-on lab experiments and computer-based exercises. Lab experiments included building hand-held seismometers, simulating the frictional behavior of faults using bricks and sandpaper, simulating tsunami generation in a mini-wave pool, and using the Internet to collect global earthquake data on a daily basis and map earthquake locations using a large classroom map. Students also use Internet resources like Google Earth and UNAVCO/EarthScope's Jules Verne Voyager Jr. interactive mapping tool to study Earth Science on a global scale. All computer-based exercises and experiments developed for Earthquakes in Action have been distributed to teachers participating in the 2006 Earthquake Education Workshop, hosted by the Visualization Center at Scripps Institution of Oceanography (http

Accessing seismic data through geological interpretation: Challenges and solutions

NASA Astrophysics Data System (ADS)

Butler, R. W.; Clayton, S.; McCaffrey, B.

2008-12-01

Between them, the world's research programs, national institutions and corporations, especially oil and gas companies, have acquired substantial volumes of seismic reflection data. Although the vast majority are proprietary and confidential, significant data are released and available for research, including those in public data libraries. The challenge now is to maximise use of these data, by providing routes to seismic not simply on the basis of acquisition or processing attributes but via the geology they image. The Virtual Seismic Atlas (VSA: www.seismicatlas.org) meets this challenge by providing an independent, free-to-use community based internet resource that captures and shares the geological interpretation of seismic data globally. Images and associated documents are explicitly indexed by extensive metadata trees, using not only existing survey and geographical data but also the geology they portray. The solution uses a Documentum database interrogated through Endeca Guided Navigation, to search, discover and retrieve images. The VSA allows users to compare contrasting interpretations of clean data thereby exploring the ranges of uncertainty in the geometric interpretation of subsurface structure. The metadata structures can be used to link reports and published research together with other data types such as wells. And the VSA can link to existing data libraries. Searches can take different paths, revealing arrays of geological analogues, new datasets while providing entirely novel insights and genuine surprises. This can then drive new creative opportunities for research and training, and expose the contents of seismic data libraries to the world.

Hydrostratigraphy characterization of the Floridan aquifer system using ambient seismic noise

NASA Astrophysics Data System (ADS)

James, Stephanie R.; Screaton, Elizabeth J.; Russo, Raymond M.; Panning, Mark P.; Bremner, Paul M.; Stanciu, A. Christian; Torpey, Megan E.; Hongsresawat, Sutatcha; Farrell, Matthew E.

2017-05-01

We investigated a new technique for aquifer characterization that uses cross-correlation of ambient seismic noise to determine seismic velocity structure of the Floridan aquifer system (FAS). Accurate characterization of aquifer systems is vital to hydrogeological research and groundwater management but is difficult due to limited subsurface data and heterogeneity. Previous research on the carbonate FAS found that confining units and high permeability flow zones have distinct seismic velocities. We deployed an array of 9 short period seismometers from 11/2013 to 3/2014 in Indian Lake State Forest near Ocala, Florida, to image the hydrostratigraphy of the aquifer system using ambient seismic noise. We find that interstation distance strongly influences the upper and lower frequency limits of the data set. Seismic waves propagating within 1.5 and 7 wavelengths between stations were optimal for reliable group velocity measurements and both an upper and lower wavelength threshold was used. A minimum of 100-250 hr of signal was needed to maximize signal-to-noise ratio and to allow cross-correlation convergence. We averaged measurements of group velocity between station pairs at each frequency band to create a network average dispersion curve. A family of 1-D shear-wave velocity profiles that best represents the network average dispersion was then generated using a Markov Chain Monte Carlo (MCMC) algorithm. The MCMC algorithm was implemented with either a fixed number of layers, or as transdimensional in which the number of layers was a free parameter. Results from both algorithms require a prominent velocity increase at ∼200 m depth. A shallower velocity increase at ∼60 m depth was also observed, but only in model ensembles created by collecting models with the lowest overall misfit to the observed data. A final round of modelling with additional prior constraints based on initial results and well logs produced a mean shear-wave velocity profile taken as the

Seismicity and Crustal Anisotropy Beneath the Western Segment of the North Anatolian Fault: Results from a Dense Seismic Array

NASA Astrophysics Data System (ADS)

Turkelli, N.; Teoman, U.; Altuncu Poyraz, S.; Cambaz, D.; Mutlu, A. K.; Kahraman, M.; Houseman, G. A.; Rost, S.; Thompson, D. A.; Cornwell, D. G.; Utkucu, M.; Gülen, L.

2013-12-01

The North Anatolian Fault (NAF) is one of the major strike slip fault systems on Earth comparable to San Andreas Fault in some ways. Devastating earthquakes have occurred along this system causing major damage and casualties. In order to comprehensively investigate the shallow and deep crustal structure beneath the western segment of NAF, a temporary dense seismic network for North Anatolia (DANA) consisting of 73 broadband sensors was deployed in early May 2012 surrounding a rectangular grid of by 70 km and a nominal station spacing of 7 km with the aim of further enhancing the detection capability of this dense seismic array. This joint project involves researchers from University of Leeds, UK, Bogazici University Kandilli Observatory and Earthquake Research Institute (KOERI), and University of Sakarya and primarily focuses on upper crustal studies such as earthquake locations (especially micro-seismic activity), receiver functions, moment tensor inversions, shear wave splitting, and ambient noise correlations. To begin with, we obtained the hypocenter locations of local earthquakes that occured within the DANA network. The dense 2-D grid geometry considerably enhanced the earthquake detection capability which allowed us to precisely locate events with local magnitudes (Ml) less than 1.0. Accurate earthquake locations will eventually lead to high resolution images of the upper crustal structure beneath the northern and southern branches of NAF in Sakarya region. In order to put additional constraints on the active tectonics of the western part of NAF, we also determined fault plane solutions using Regional Moment Tensor Inversion (RMT) and P wave first motion methods. For the analysis of high quality fault plane solutions, data from KOERI and the DANA project were merged. Furthermore, with the aim of providing insights on crustal anisotropy, shear wave splitting parameters such as lag time and fast polarization direction were obtained for local events recorded

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

health monitoring'' and by the "Centre of Integrated Geomorphology for the Mediterranean Area - CGIAM" within the Framework Agreement with the University of Basilicata "Study, Research and Experimentation in the Field of Analysis and Monitoring of Seismic Vulnerability of Strategic and Relevant Buildings for the purposes of Civil Protection and Development of Innovative Strategies of Seismic Reinforcement".

Validating induced seismicity forecast models—Induced Seismicity Test Bench

NASA Astrophysics Data System (ADS)

Király-Proag, Eszter; Zechar, J. Douglas; Gischig, Valentin; Wiemer, Stefan; Karvounis, Dimitrios; Doetsch, Joseph

2016-08-01

Induced earthquakes often accompany fluid injection, and the seismic hazard they pose threatens various underground engineering projects. Models to monitor and control induced seismic hazard with traffic light systems should be probabilistic, forward-looking, and updated as new data arrive. In this study, we propose an Induced Seismicity Test Bench to test and rank such models; this test bench can be used for model development, model selection, and ensemble model building. We apply the test bench to data from the Basel 2006 and Soultz-sous-Forêts 2004 geothermal stimulation projects, and we assess forecasts from two models: Shapiro and Smoothed Seismicity (SaSS) and Hydraulics and Seismics (HySei). These models incorporate a different mix of physics-based elements and stochastic representation of the induced sequences. Our results show that neither model is fully superior to the other. Generally, HySei forecasts the seismicity rate better after shut-in but is only mediocre at forecasting the spatial distribution. On the other hand, SaSS forecasts the spatial distribution better and gives better seismicity rate estimates before shut-in. The shut-in phase is a difficult moment for both models in both reservoirs: the models tend to underpredict the seismicity rate around, and shortly after, shut-in.

Seismic investigation of the Kunlun Fault: Analysis of the INDEPTH IV 2-D active-source seismic dataset

NASA Astrophysics Data System (ADS)

Seelig, William George

The Tibetan Plateau has experienced significant crustal thickening and deformation since the continental subduction and collision of the Asian and Indian plates in the Eocene. Deformation of the northern Tibetan Plateau is largely accommodated by strike-slip faulting. The Kunlun Fault is a 1000-km long strike-slip fault near the northern boundary of the Plateau that has experienced five magnitude 7.0 or greater earthquakes in the past 100 years and represents a major rheological boundary. Active-source, 2-D seismic reflection/refraction data, collected as part of project INDEPTH IV (International Deep Profiling of Tibet and the Himalaya, phase IV) in 2007, was used to examine the structure and the dip of the Kunlun fault. The INDEPTH IV data was acquired to better understand the tectonic evolution of the northeastern Tibetan Plateau, such as the far-field deformation associated with the continent-continent collision and the potential subduction of the Asian continent beneath northern Tibet. Seismic reflection common depth point (CDP) stacks were examined to look for reflectivity patterns that may be associated with faulting. A possible reflection from the buried North Kunlun Thrust (NKT) is identified at 18-21 km underneath the East Kunlun Mountains, with an estimated apparent dip of 15°S and thrusting to the north. Minimally-processed shot gathers were also inspected for reflections off near-vertical structures such as faults and information on first-order velocity structure. Shot offset and nearest receiver number to reflection was catalogued to increase confidence of picks. Reflections off the North Kunlun (NKF) and South Kunlun Faults (SKF) were identified and analyzed for apparent dip and subsurface geometry. Fault reflection analysis found that the North Kunlun Fault had an apparent dip of approximately 68ºS to an estimated depth of 5 km, while the South Kunlun Fault dipped at approximately 78ºN to an estimated 3.5 km depth. Constraints on apparent dip and

Short-Period Seismic Noise in Vorkuta (Russia)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kishkina, S B; Spivak, A A; Sweeney, J J

Cultural development of new subpolar areas of Russia is associated with a need for detailed seismic research, including both mapping of regional seismicity and seismic monitoring of specific mining enterprises. Of special interest are the northern territories of European Russia, including shelves of the Kara and Barents Seas, Yamal Peninsula, and the Timan-Pechora region. Continuous seismic studies of these territories are important now because there is insufficient seismological knowledge of the area and an absence of systematic data on the seismicity of the region. Another task of current interest is the necessity to consider the seismic environment in the design,more » construction, and operation of natural gas extracting enterprises such as the construction of the North European Gas Pipeline. Issues of scientific importance for seismic studies in the region are the complex geodynamical setting, the presence of permafrost, and the complex tectonic structure. In particular, the Uralian Orogene (Fig. 1) strongly affects the propagation of seismic waves. The existing subpolar seismic stations [APA (67,57{sup o}N; 33,40{sup o}E), LVZ (67,90{sup o}N; 34,65{sup o}E), and NRIL (69,50{sup o}N; 88,40{sup o}E)] do not cover the extensive area between the Pechora and Ob Rivers (Fig. 1). Thus seismic observations in the Vorkuta area, which lies within the area of concern, represent a special interest. Continuous recording at a seismic station near the city of Vorkuta (67,50{sup o}N; 64,11{sup o}E) [1] has been conducted since 2005 for the purpose of regional seismic monitoring and, more specifically, detection of seismic signals caused by local mining enterprises. Current surveys of local seismic noise [7,8,9,11], are particularly aimed at a technical survey for the suitability of the site for installation of a small-aperture seismic array, which would include 10-12 recording instruments, with the Vorkuta seismic station as the central element. When constructed, this

Cluster Computing For Real Time Seismic Array Analysis.

NASA Astrophysics Data System (ADS)

Martini, M.; Giudicepietro, F.

A seismic array is an instrument composed by a dense distribution of seismic sen- sors that allow to measure the directional properties of the wavefield (slowness or wavenumber vector) radiated by a seismic source. Over the last years arrays have been widely used in different fields of seismological researches. In particular they are applied in the investigation of seismic sources on volcanoes where they can be suc- cessfully used for studying the volcanic microtremor and long period events which are critical for getting information on the volcanic systems evolution. For this reason arrays could be usefully employed for the volcanoes monitoring, however the huge amount of data produced by this type of instruments and the processing techniques which are quite time consuming limited their potentiality for this application. In order to favor a direct application of arrays techniques to continuous volcano monitoring we designed and built a small PC cluster able to near real time computing the kinematics properties of the wavefield (slowness or wavenumber vector) produced by local seis- mic source. The cluster is composed of 8 Intel Pentium-III bi-processors PC working at 550 MHz, and has 4 Gigabytes of RAM memory. It runs under Linux operating system. The developed analysis software package is based on the Multiple SIgnal Classification (MUSIC) algorithm and is written in Fortran. The message-passing part is based upon the LAM programming environment package, an open-source imple- mentation of the Message Passing Interface (MPI). The developed software system includes modules devote to receiving date by internet and graphical applications for the continuous displaying of the processing results. The system has been tested with a data set collected during a seismic experiment conducted on Etna in 1999 when two dense seismic arrays have been deployed on the northeast and the southeast flanks of this volcano. A real time continuous acquisition system has been simulated by

Seismological investigation of earthquakes in the New Madrid Seismic Zone. Final report, September 1986--December 1992

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herrmann, R.B.; Nguyen, B.

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 toolmore » 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.« less

Mass Wasting in Planetary Environments: Implications for Seismicity

NASA Technical Reports Server (NTRS)

Weber, Renee; Nahm, Amanda; Schmerr, Nick

2015-01-01

On Earth, mass wasting events such as rock falls and landslides are well known consequences of seismic activity. Here we investigate the regional effects of seismicity in planetary environments with the goal of determining whether such surface features on the Moon, Mars, and Mercury could be triggered by fault motion.

Influence of LOD variations on seismic energy release

NASA Astrophysics Data System (ADS)

Riguzzi, F.; Krumm, F.; Wang, K.; Kiszely, M.; Varga, P.

2009-04-01

Tidal friction causes significant time variations of geodynamical parameters, among them geometrical flattening. The axial despinning of the Earth due to tidal friction through the change of flattening generates incremental meridional and azimuthal stresses. The stress pattern in an incompressible elastic upper mantle and crust is symmetric to the equator and has its inflection points at the critical latitude close to ±45°. Consequently the distribution of seismic energy released by strong, shallow focus earthquakes should have also sharp maxima at this latitude. To investigate the influence of length of day (LOD) variations on earthquake activity an earthquake catalogue of strongest seismic events (M>7.0) was completed for the period 1900-2007. It is shown with the use of this catalogue that for the studied time-interval the catalogue is complete and consists of the seismic events responsible for more than 90% of released seismic energy. Study of the catalogue for earthquakes M>7.0 shows that the seismic energy discharged by the strongest seismic events has significant maxima at ±45°, what renders probably that the seismic activity of our planet is influenced by an external component, i.e. by the tidal friction, which acts through the variation of the hydrostatic figure of the Earth caused by it. Distribution along the latitude of earthquake numbers and energies was investigated also for the case of global linear tectonic structures, such as mid ocean ridges and subduction zones. It can be shown that the number of the shallow focus shocks has a repartition along the latitude similar to the distribution of the linear tectonic structures. This means that the position of foci of seismic events is mainly controlled by the tectonic activity.

Using geologic maps and seismic refraction in pavement-deflection analysis

DOT National Transportation Integrated Search

1999-10-01

The researchers examined the relationship between three data types -- geologic maps, pavement deflection, and seismic refraction data -- from diverse geologic settings to determine whether geologic maps and seismic data might be used to interpret def...

Seismic hazard estimation of northern Iran using smoothed seismicity

NASA Astrophysics Data System (ADS)

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

2017-07-01

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

Impact of Reservoir Fluid Saturation on Seismic Parameters: Endrod Gas Field, Hungary

NASA Astrophysics Data System (ADS)

El Sayed, Abdel Moktader A.; El Sayed, Nahla A.

2017-12-01

Outlining the reservoir fluid types and saturation is the main object of the present research work. 37 core samples were collected from three different gas bearing zones in the Endrod gas field in Hungary. These samples are belonging to the Miocene and the Upper - Lower Pliocene. These samples were prepared and laboratory measurements were conducted. Compression and shear wave velocity were measured using the Sonic Viewer-170-OYO. The sonic velocities were measured at the frequencies of 63 and 33 kHz for compressional and shear wave respectively. All samples were subjected to complete petrophysical investigations. Sonic velocities and mechanical parameters such as young’s modulus, rigidity, and bulk modulus were measured when samples were saturated by 100%-75%-0% brine water. Several plots have been performed to show the relationship between seismic parameters and saturation percentages. Robust relationships were obtained, showing the impact of fluid saturation on seismic parameters. Seismic velocity, Poisson’s ratio, bulk modulus and rigidity prove to be applicable during hydrocarbon exploration or production stages. Relationships among the measured seismic parameters in gas/water fully and partially saturated samples are useful to outline the fluid type and saturation percentage especially in gas/water transitional zones.

Application of random seismic inversion method based on tectonic model in thin sand body research

NASA Astrophysics Data System (ADS)

Dianju, W.; Jianghai, L.; Qingkai, F.

2017-12-01

The oil and gas exploitation at Songliao Basin, Northeast China have already progressed to the period with high water production. The previous detailed reservoir description that based on seismic image, sediment core, borehole logging has great limitations in small scale structural interpretation and thin sand body characterization. Thus, precise guidance for petroleum exploration is badly in need of a more advanced method. To do so, we derived the method of random seismic inversion constrained by tectonic model.It can effectively improve the depicting ability of thin sand bodies, combining numerical simulation techniques, which can credibly reducing the blindness of reservoir analysis from the whole to the local and from the macroscopic to the microscopic. At the same time, this can reduce the limitations of the study under the constraints of different geological conditions of the reservoir, accomplish probably the exact estimation for the effective reservoir. Based on the research, this paper has optimized the regional effective reservoir evaluation and the productive location adjustment of applicability, combined with the practical exploration and development in Aonan oil field.

Active seismic experiment

NASA Technical Reports Server (NTRS)

Kovach, R. L.; Watkins, J. S.; Talwani, P.

1972-01-01

The Apollo 16 active seismic experiment (ASE) was designed to generate and monitor seismic waves for the study of the lunar near-surface structure. Several seismic energy sources are used: an astronaut-activated thumper device, a mortar package that contains rocket-launched grenades, and the impulse produced by the lunar module ascent. Analysis of some seismic signals recorded by the ASE has provided data concerning the near-surface structure at the Descartes landing site. Two compressional seismic velocities have so far been recognized in the seismic data. The deployment of the ASE is described, and the significant results obtained are discussed.

Seismic reflection imaging of shallow oceanographic structures

NASA Astrophysics Data System (ADS)

Piété, Helen; Marié, Louis; Marsset, Bruno; Thomas, Yannick; Gutscher, Marc-André

2013-05-01

Multichannel seismic (MCS) reflection profiling can provide high lateral resolution images of deep ocean thermohaline fine structure. However, the shallowest layers of the water column (z < 150 m) have remained unexplored by this technique until recently. In order to explore the feasibility of shallow seismic oceanography (SO), we reprocessed and analyzed four multichannel seismic reflection sections featuring reflectors at depths between 10 and 150 m. The influence of the acquisition parameters was quantified. Seismic data processing dedicated to SO was also investigated. Conventional seismic acquisition systems were found to be ill-suited to the imaging of shallow oceanographic structures, because of a high antenna filter effect induced by large offsets and seismic trace lengths, and sources that typically cannot provide both a high level of emission and fine vertical resolution. We considered a test case, the imagery of the seasonal thermocline on the western Brittany continental shelf. New oceanographic data acquired in this area allowed simulation of the seismic acquisition. Sea trials of a specifically designed system were performed during the ASPEX survey, conducted in early summer 2012. The seismic device featured: (i) four seismic streamers, each consisting of six traces of 1.80 m; (ii) a 1000 J SIG sparker source, providing a 400 Hz signal with a level of emission of 205 dB re 1 μPa @ 1 m. This survey captured the 15 m thick, 30 m deep seasonal thermocline in unprecedented detail, showing images of vertical displacements most probably induced by internal waves.

Investigation of the local stress perturbation in Long Valley, California, by coupling seismic analyses and FEM numerical modeling

NASA Astrophysics Data System (ADS)

Lin, G.; Albino, F.; Amelung, F.

2017-12-01

Long Valley Caldera in eastern California is well known for producing numerous volcanic eruptions over the past 3 Myr. There has been a stress perturbation in the vicinity of the caldera with respect to the regional stress field. In this study, we combine seismic analyses and finite-element numerical modeling to investigate this local stress anomaly. We first compute focal mechanisms for earthquakes relocated by using a three-dimensional (3-D) seismic velocity model and waveform cross-correlation data. The final 42,000 good-quality focal solutions show that the mechanisms are dominated by approximately the same amount of normal faulting and strike-slip and much fewer reverse focal types. These focal mechanisms are then used to invert for the stress field in the study area by applying the SATSI algorithm. The orientations of the inverted minimum horizontal principal stress (ShMIN) greatly agree with those in previous studies based on analyses of focal mechanisms, borehole breakouts, and fault offsets. The NE-SW oriented ShMIN in the resurgent dome and south moat of the caldera is in contrast to the dominating E-W orientation in the western Basin and Range province and Mammoth Mountain. We then investigate which mechanism most likely causes this local stress perturbation by applying 3-D Finite Element Modeling (FEM). Mechanical properties (e.g., density, Poisson's ratio, and Young's Modulus) used in the model are derived from the latest 3-D seismic tomography model. Taking into account an initial stress field, we examine stress perturbations resulting from different sources: (1) pressurization of a magma reservoir, (2) dyking event, and (3) tectonic faulting; and compute the corresponding stress field orientation for each and compare it with the observations.

Mobile seismic exploration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dräbenstedt, A., E-mail: a.draebenstedt@polytec.de, E-mail: rembe@iei.tu-clausthal.de, E-mail: ulrich.polom@liag-hannover.de; Seyfried, V.; Cao, X.

2016-06-28

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

Marine and land active-source seismic investigation of geothermal potential, tectonic structure, and earthquake hazards in Pyramid Lake, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eisses, A.; Kell, A.; Kent, G.

Amy Eisses, Annie M. Kell, Graham Kent, Neal W. Driscoll, Robert E. Karlin, Robert L. Baskin, John N. Louie, Kenneth D. Smith, Sathish Pullammanappallil, 2011, Marine and land active-source seismic investigation of geothermal potential, tectonic structure, and earthquake hazards in Pyramid Lake, Nevada: presented at American Geophysical Union Fall Meeting, San Francisco, Dec. 5-9, abstract NS14A-08.

The Novaya Zemlya Event of 31 December 1992 and Seismic Identification Issues: Annual Seismic Research Symposium (15th) Held in Vail, Colorado on 8-10 September 1993

DTIC Science & Technology

1993-09-10

1993). A bootstrap generalizedlikelihood ratio test in discriminant analysis, Proc. 15th Annual Seismic Research Symposium, in press. I Hedlin, M., J... ratio indicate that the event does not belong to the first class. The bootstrap technique is used here as well to set the critical value of the test ...Methodist University. Baek, J., H. L. Gray, W. A. Woodward and M.D. Fisk (1993). A Bootstrap Generalized Likelihood Ratio Test in Discriminant

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woolery, Edward W; Wang, Zhenming; Sturchio, Neil C

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 bedrockmore » 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).« less

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

NASA Astrophysics Data System (ADS)

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

2017-10-01

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

Seismic Risk Assessment of Italian Seaports Using GIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartolomei, Anna; Corigliano, Mirko; Lai, Carlo G.

Seaports are crucial elements in the export and import of goods and/or on the flow of travellers in the tourism industry of many industrialised nations included Italy. Experience gained from recent earthquakes (e.g. 1989 Loma Prieta in USA, 1995 Hyogoken-Nanbu and 2003 Tokachi-Oki in Japan) have dramatically demonstrated the seismic vulnerability of seaport structures and the severe damage that can be caused by ground shaking. In Italy, the Department of Civil Protection has funded a research project to develop a methodology for the seismic design of new marginal wharves and assessment of existing structures at seaports located in areas ofmore » medium or high seismicity. This paper shows part of the results of this research project, currently underway, with particular reference to the seismic risk assessment through an interactive, geographically referenced database (GIS). Standard risk assessment have been carried out for the Gioia Tauro port in Calabria (Italy) using the empirical curves implemented by the National Institute of Building Sciences (NIBS, 2004)« less

Investigation of Seismic Events associated with the Sinkhole at Napoleonville Salt Dome, Louisiana

NASA Astrophysics Data System (ADS)

Nayak, A.; Dreger, D. S.

2015-12-01

This study describes the ongoing efforts in analysis of the intense sequence of complex seismic events associated with the formation of a large sinkhole at Napoleonville Salt Dome, Assumption Parish, Louisiana in August 2012. Point source centroid seismic moment tensor (MT) inversion of these events using data from a temporary network of broadband stations established by the United States Geological Survey had previously revealed large volume-increase components. We investigate the effect of 3D velocity structure of the salt dome on wave propagation in the frequency range of interest (0.1-0.3 Hz) by forward modeling synthetic waveforms using MT solutions that were computed using Green's functions assuming two separate 1D velocity models for stations over the salt dome and stations on the sedimentary strata surrounding the salt dome separately. We also use a matched filter technique to detect smaller events that went undetected by the automated grid-search based scanning and MT inversion algorithm using the waveforms of the larger events as templates. We also analyze the change in spectral content of the events, many of which exhibit a spectral peak at 0.4 Hz with a duration of > 60 seconds. The decrease in spectral amplitudes with distance also gives an estimate of high anelastic attenuation that damps reverberations within the shallow low velocity layers. Finally, we use noise cross-correlation analysis to explore changes in the green's functions during the development of the sinkhole and verify the sediment velocity model by comparing observed and synthetic surface wave dispersion.

Investigating the Concept of Using Airglow Measurements to Detect Seismicity on Venus

NASA Astrophysics Data System (ADS)

Kenda, Balthasar; Lognonné, Philippe; Komjathy, Attila; Banerdt, Bruce; Cutts, Jim; Soret, Lauriane; Jackson, Jennifer

2017-04-01

The internal structure and dynamics of Venus are poorly constrained by observations. Seismology is among the best candidates for probing the interior of the planet, and it would also provide indispensable information about the present-day tectonic activity of Venus. However, due to the extreme surface temperatures, a long-duration seismic station seems to be beyond the technical capabilities achievable today. Nonetheless, the thick and dense atmosphere, which strongly couples with the ground, gives rise to the attractive option of detecting seismic waves from quakes within the atmosphere itself (Garcia et al., 2005, Lognonné and Johnson, 2007, 2015) using in-situ or remote-sensing measurements (Cutts et al., 2015). Here, we consider the bright airglow emission of O2 at 1.27 μm on the nightside of Venus and we model the intensity fluctuations induced by Venus quakes. Synthetic seismograms in the airglow layer, at 90-120 km altitude, are computed using normal-mode summation for a fully coupled solid planet-atmosphere system, including the effects of molecular relaxation of CO2 and a radiative boundary condition at the top of the atmosphere (Lognonné et al., 2016). The corresponding variations in the volumetric emission rate, calculated for realistic background intensities of the airglow (Soret et al., 2012), are then vertically integrated to reproduce the signals that would be seen from orbit. The noise level of existing airglow cameras suggests that the Rayleigh waves generated by quakes of magnitude 5 and above occurring on the nightside of the planet may be detectable up to about 60° in epicentral distance. A significant advantage of this technique is that a single orbiting camera may be sufficient to serve the role of a seismic network. By identifying and tracking the waves it is indeed possible to locate the source, estimate the magnitude and measure the horizontal surface-wave propagation velocities on Venus. In particular, it is expected that this would

CAFE: a seismic investigation of water percolation in the Cascadia subduction zone

NASA Astrophysics Data System (ADS)

Rondenay, S.; Abers, G. A.; Creager, K. C.; Malone, S. D.; MacKenzie, L.; Zhang, Z.; van Keken, P. E.; Wech, A. G.; Sweet, J. R.; Melbourne, T. I.; Hacker, B. R.

2008-12-01

Subduction zones transport water into the Earth's interior. The subsequent release of this water through dehydration reactions may trigger intraslab earthquakes and arc volcanism, regulate slip on the plate interface, control plate buoyancy, and regulate the long-term budget of water on the planet's surface. As part of Earthscope, we have undertaken an experiment named CAFE (Cascadia Arrays for Earthscope) seeking to better constrain these effects in the Cascadia subduction zone. The basic experiment has four components: (1) a 47-element broadband imaging array of Flexible Array instruments integrated with Bigfoot; (2) three small-aperture seismic arrays with 15 additional short-period instruments near known sources of Episodic Tremor and Slip (ETS) events; (3) analysis of the PBO and PANGA GPS data sets to define the details of episodic slip events; and (4) integrative modeling with complementary constraints from petrology and geodynamics. Here, we present a summary of the results that have been obtained to date by CAFE, with a focus on high-resolution seismic imaging. A 250 km-long by 120 km-deep seismic profile extending eastward from the Washington coast was generated by 2-D Generalized Radon Transform Inversion of the broadband data. It images the subducted crust as a shallow-dipping, low-velocity layer from 20km depth beneath the coast to 40km depth beneath the forearc. The termination of the low-velocity layer is consistent with the depth at which hydrated metabasalts of the subducted crust are expected to undergo eclogitization, a reaction that is accompanied by the release of water and an increase in seismic velocities. Slab earthquakes are located in both the oceanic crust and mantle at depths <40 km, and exclusively in the oceanic mantle at greater depth, as would be expected if they are related to slab dehydration. Two ETS events have occurred during the course of the deployment. They were precisely located and are confined to the region above which the

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

NASA Astrophysics Data System (ADS)

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

2014-07-01

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

Seismic modeling of Earth's 3D structure: Recent advancements

NASA Astrophysics Data System (ADS)

Ritsema, J.

2008-12-01

Global models of Earth's seismic structure continue to improve due to the growth of seismic data sets, implementation of advanced wave propagations theories, and increased computational power. In my presentation, I will summarize seismic tomography results from the past 5-10 years. I will compare the most recent P and S velocity models, discuss model resolution and model interpretation, and present an, admittedly biased, list of research directions required to develop the next generation 3D models.

Application of uphole data from petroleum seismic surveys to groundwater investigations, Abu Dhabi (United Arab Emirates)

USGS Publications Warehouse

Woodward, D.; Menges, C.M.

1991-01-01

Velocity data from uphole surveys were used to map the water table and the contact at the base dune sand/top alluvium as part of a joint National Drilling Company-United States Geological Survey Ground Water Research Project in the Emirate of Abu Dhabi. During 1981-1983, a reconnaissance seismic survey was conducted for petroleum exploration in the eastern region of Abu Dhabi. Approximately 2800 kilometers of seismic data, consisting of 92 lines, were acquired in the 2500 km2 concession area near Al Ain. Uphole surveys were conducted about 2 km apart along each seismic line, and were used to calculate weathering corrections required to further process in the seismic data. Approximately 1300 uphole surveys were completed in the concession area between March 1981 and June 1983. Reinterpretation of the velocity profiles derived from the uphole surveys provided data for determining the following subsurface layers, listed in descending order: (1) a surficial, unconsolidated weathering layer with a velocity from 300 to 450 m/s; (2) surficial dune sand, from 750 to 900 m/s; (3) unsaturated, unconsolidated alluvium, from 1000 to 1300 m/s; and (4) saturated, unconsolidated alluvium, from 1900 to 2200 m/s. Two interfaces-the water table and the base dune sand/top alluvium - were identified and mapped from boundaries between these velocity layers. Although the regional water table can fluctuate naturally as much as 3 m per year in this area and the water-table determinations from the uphole data span a 27-month period, an extremely consistent and interpretable water-table map was derived from the uphole data throughout the entire concession area. In the northern part of the area, unconfined groundwater moves northward and northwestward toward the Arabian Gulf; and in the central and southern parts of the area, groundwater moves westward away from the Oman Mountains. In the extreme southern area east of Jabal Hafit, groundwater moves southward into Oman. The map of the base

A seismic refraction technique used for subsurface investigations at Meteor Crater, Arizona

NASA Technical Reports Server (NTRS)

Ackermann, H. D.; Godson, R. H.; Watkins, J. S.

1975-01-01

A seismic refraction technique for interpreting the subsurface shape and velocity distribution of an anomalous surface feature such as an impact crater is described. The method requires the existence of a relatively deep refracting horizon and combines data obtained from both standard shallow refraction spreads and distant offset shots by using the deep refractor as a source of initial arrivals. Results obtained from applying the technique to Meteor crater generally agree with the known structure of the crater deduced by other investigators and provide new data on an extensive fractured zone surrounding the crater. The breccia lens is computed to extend roughly 190 m below the crater floor, about 30 m less than the value deduced from early drilling data. Rocks around the crater are fractured as distant as 900 m from the rim crest and to a depth of at least 800 m beneath the crater floor.

Progressive Seismic Failure, Seismic Gap, and Great Seismic Risk across the Densely Populated North China Basin

NASA Astrophysics Data System (ADS)

Yin, A.; Yu, X.; Shen, Z.

2014-12-01

Although the seismically active North China basin has the most complete written records of pre-instrumentation earthquakes in the world, this information has not been fully utilized for assessing potential earthquake hazards of this densely populated region that hosts ~200 million people. In this study, we use the historical records to document the earthquake migration pattern and the existence of a 180-km seismic gap along the 600-km long right-slip Tangshan-Hejian-Cixian (THC) fault zone that cuts across the North China basin. The newly recognized seismic gap, which is centered at Tianjin with a population of 11 million people and ~120 km from Beijing (22 million people) and Tangshan (7 million people), has not been ruptured in the past 1000 years by M≥6 earthquakes. The seismic migration pattern in the past millennium suggests that the epicenters of major earthquakes have shifted towards this seismic gap along the THC fault, which implies that the 180- km gap could be the site of the next great earthquake with M≈7.6 if it is ruptured by a single event. Alternatively, the seismic gap may be explained by aseismic creeping or seismic strain transfer between active faults.

Investigating the relationship between seismicity and fluid injection in the Barnett Shale, Texas using coupled poroelastic model and surface deformation data

NASA Astrophysics Data System (ADS)

Zhai, G.; Shirzaei, M.

2017-12-01

Across the Barnett Shale, Texas a noticeable increase in seismic activity was observed during 2007 and 2015, which was accompanied by high volume injection at several nearby disposal wells. Many studies focused on the positive correlation between injection rate at individual wells and the adjacent seismicity, suggesting that seismicity is triggered or induced due to increased pore fluid pressure associated with fluid injection in hydraulically connected geological units. However, investigating temporal evolution of total volume of injected fluid and concurrent earthquakes in a larger area indicates more complex patterns, requiring a more comprehensive analysis of the spatiotemporal evolution of coupled poroelastic stress and pore fluid pressure. In this study, we created a coupled poroelastic model to simulate large scale spatiotemporal evolution of pore pressure, poroelastic stresses, and Coulomb failure stress in the Barnett Shale using injection time series of 96 high-volume injection wells spanning from 2007 to 2015. We additionally account for a layered poroelastic medium, where its parameters are set up using geological maps and seismic tomographic data sets. Fault orientations and relevant frictional properties are also extracted from published literatures. We further integrate observation of surface deformation obtained from interferometric processing of 16 ALOS L-Band SAR images to optimize rock hydraulic diffusivity and constrain the extent to which fluid may migrate. The preliminary modeling result shows that poroelastic stress is only 10% of pore pressure. However, the superimposition of these two effects is spatially and temporally responsible for the occurrence of earthquakes in the Barnett Shale. Also, not all area with increased Coulomb failure stress experiences elevated seismicity, suggesting possible heterogeneous background tectonic stresses, lacking pre-existing faults, and/or heterogeneous fault orientations.

National Seismic Network of Georgia

NASA Astrophysics Data System (ADS)

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

2016-12-01

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

Seismic Sources for the Territory of Georgia

NASA Astrophysics Data System (ADS)

Tsereteli, N. S.; Varazanashvili, O.

2011-12-01

The southern Caucasus is an earthquake prone region where devastating earthquakes have repeatedly caused significant loss of lives, infrastructure and buildings. High geodynamic activity of the region expressed in both seismic and aseismic deformations, is conditioned by the still-ongoing convergence of lithospheric plates and northward propagation of the Afro-Arabian continental block at a rate of several cm/year. The geometry of tectonic deformations in the region is largely determined by the wedge-shaped rigid Arabian block intensively intended into the relatively mobile Middle East-Caucasian region. Georgia is partner of ongoing regional project EMME. The main objective of EMME is calculation of Earthquake hazard uniformly with heights standards. One approach used in the project is the probabilistic seismic hazard assessment. In this approach the first parameter requirement is the definition of seismic source zones. Seismic sources can be either faults or area sources. Seismoactive structures of Georgia are identified mainly on the basis of the correlation between neotectonic structures of the region and earthquakes. Requirements of modern PSH software to geometry of faults is very high. As our knowledge of active faults geometry is not sufficient, area sources were used. Seismic sources are defined as zones that are characterized with more or less uniform seismicity. Poor knowledge of the processes occurring in deep of the Earth is connected with complexity of direct measurement. From this point of view the reliable data obtained from earthquake fault plane solution is unique for understanding the character of a current tectonic life of investigated area. There are two methods of identification if seismic sources. The first is the seimsotectonic approach, based on identification of extensive homogeneous seismic sources (SS) with the definition of probability of occurrence of maximum earthquake Mmax. In the second method the identification of seismic sources

Time-Independent Annual Seismic Rates, Based on Faults and Smoothed Seismicity, Computed for Seismic Hazard Assessment in Italy

NASA Astrophysics Data System (ADS)

Murru, M.; Falcone, G.; Taroni, M.; Console, R.

2017-12-01

In 2015 the Italian Department of Civil Protection, started a project for upgrading the official Italian seismic hazard map (MPS04) inviting the Italian scientific community to participate in a joint effort for its realization. We participated providing spatially variable time-independent (Poisson) long-term annual occurrence rates of seismic events on the entire Italian territory, considering cells of 0.1°x0.1° from M4.5 up to M8.1 for magnitude bin of 0.1 units. Our final model was composed by two different models, merged in one ensemble model, each one with the same weight: the first one was realized by a smoothed seismicity approach, the second one using the seismogenic faults. The spatial smoothed seismicity was obtained using the smoothing method introduced by Frankel (1995) applied to the historical and instrumental seismicity. In this approach we adopted a tapered Gutenberg-Richter relation with a b-value fixed to 1 and a corner magnitude estimated with the bigger events in the catalogs. For each seismogenic fault provided by the Database of the Individual Seismogenic Sources (DISS), we computed the annual rate (for each cells of 0.1°x0.1°) for magnitude bin of 0.1 units, assuming that the seismic moments of the earthquakes generated by each fault are distributed according to the same tapered Gutenberg-Richter relation of the smoothed seismicity model. The annual rate for the final model was determined in the following way: if the cell falls within one of the seismic sources, we merge the respective value of rate determined by the seismic moments of the earthquakes generated by each fault and the value of the smoothed seismicity model with the same weight; if instead the cells fall outside of any seismic source we considered the rate obtained from the spatial smoothed seismicity. Here we present the final results of our study to be used for the new Italian seismic hazard map.

Implosion, earthquake, and explosion recordings from the 2000 Seattle Kingdome Seismic Hazards Investigation of Puget Sound (SHIPS), Washington

USGS Publications Warehouse

Brocher, Thomas M.; Pratt, Thomas L.; Weaver, Craig S.; Snelson, Catherine M.; Frankel, Arthur D.

2002-01-01

This report describes seismic data obtained in Seattle, Washington, March 24-28, 2000, during a Seismic Hazards Investigation of Puget Sound (SHIPS). The seismic recordings obtained by this SHIPS experiment, nicknamed Kingdome SHIPS, were designed to (1) measure site responses throughout Seattle and to (2) help define the location of the Seattle fault. During Kingdome SHIPS, we recorded the Kingdome implosion, four 150-lb (68-kg) shots, and a Mw = 7.6 teleseism using a dense network of seismographs deployed throughout Seattle. The seismographs were deployed at a nominal spacing of 1 km in a hexagonal grid extending from Green Lake in the north to Boeing Field in the south. The Seattle Kingdome was a domed sports stadium located in downtown Seattle near the Seattle fault. The Seattle Kingdome was imploded (demolished) at 8:32 AM local time (16:32 UTC) on March 26 (JD 086), 2000. The seismic energy produced by implosion of the Kingdome was equivalent to a local earthquake magnitude of 2.3. Strong impacts produced by the implosion of the Kingdome generated seismic arrivals to frequencies as low as 0.1 Hz. Two shots located north of the Seattle fault, where the charges were detonated within the ground water column (Discovery and Magnuson Parks), were much more strongly coupled than were the two shots to the south of the Seattle fault, where the shots were detonated above the water table (Lincoln and Seward Parks). Thirty-eight RefTek stations, scattered throughout Seattle, recorded the Mw = 7.6 Japan Volcano Islands earthquake (22.4°N, 143.6°E, 104 km depth) of 28 March 2000 (JD 088). This teleseism produced useful signals for periods between 4 and 7 seconds. Only a few recordings of small magnitude local earthquakes were made, and these recordings are not presented. In this report, we describe the acquisition of these data, discuss the processing and merging of the data into common shot gathers, and illustrate the acquired data. We also describe the format and

Seismic investigation on the Littoral Faults Zone in the northern continental margin of South China Sea

NASA Astrophysics Data System (ADS)

Sun, J.; Xu, H.; Xia, S.; Cao, J.; Wan, K.

2017-12-01

The continental margin of the northern South China Sea (SCS) had experienced continuous evolution from an active continental margin in the late Mesozoic to a passive continental margin in the Cenozoic. The 1200km-long Littoral Faults Zone (LFZ) off the mainland South China was suggested to represent one of the sub-plate boundaries and play a key role during the evolution. Besides, four devastating earthquakes with magnitude over 7 and another 11 destructive events with M>6 were documented to have occurred along the LFZ. However, its approximity to the shoreline, the shallow water depth, and the heavy fishing activities make it hard to conduct a marine seismic investigation. As a result, understandings about the LFZ before 2000 were relatively poor and mostly descriptive. After two experiments of joint onshore-offshore wide-angle seismic surveys in the 1st decade of this century, several cruses aiming to unveil the deep structure of the LFZ were performed in the past few years, with five joint onshore-offshore wide-angle seismic survey profiles completed. Each of these profiles is perpendicular to the shoreline, with four to five seismometers of campaign mode deployed on the landside and over ten Ocean Bottom Seismometers (OBSs) spacing at 20km deployed on the seaside. Meanwhile, multi-channel seismic (MCS) data along these profiles were obtained simultaneously. Based on these data, velocity models from both forward modeling and inversion were obtained. According to these models, the LFZ was imaged to be a low-velocity fractured zone dipping to the SSE-SE at a high-angle and cutting through the thinned continental crust at some locations. Width of the fractured zone varies from 6km to more than 10km from site to site. With these results, it is suggested that the LFZ accommodates the stresses from both the east side, where the Eurasia/Philippine Sea plate converging and mountain building is ongoing, and the west side, where a strike-slip between the Indochina

Anisotropic Lithospheric Structure of Southern Madagascar from Ambient Seismic Noise

NASA Astrophysics Data System (ADS)

Dreiling, J.; Tilmann, F. J.; Yuan, X.; Rumpker, G.

2016-12-01

The island of Madagascar occupied a key region in both the assembly and the multi-stage breakup of Gondwana. Madagascar consists of amalgamated continental material comprising several distinct tectonic units. Because of its key role in the assembly of Gondwana, numerous geological and geophysical investigations have been carried out in Madagascar to understand the evolution of Gondwana.The aim of this study is to characterize the lithospheric structure of Southern Madagascar using ambient seismic noise correlation. Radial anisotropy is determined to learn about the crust/mantle deformation around the central Southern Madagascan shear zones (i.e. the Ampanihy, Beraketa and Ranotsara shear zones) and to shed light on the geological development of Madagascar and its role during the breakup of Gondwana. In the analysis we included seismic data from the SELASOMA project in Southern Madagascar, which is a passive seismic experiment carried out by the GFZ German Research Centre for Geosciences from May 2012 to May 2014. Seismic data recorded by 61 three-component seismometers were pre-processed and cross-correlated. Group velocity dispersion curves were picked manually for the vertical-vertical and transverse-transverse component correlations, which represent the Rayleigh (ZZ) and Love (TT) surface waves, respectively. Velocities from periods between 0.7 and 20 seconds are used for tomography and computation of radial anisotropy of the lithosphere.

Measuring the effects of pore-pressure changes on seismic amplitude using crosswell continuous active-source seismic monitoring (CASSM)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchesini, Pierpaolo; Daley, Thomas; Ajo-Franklin, Jonathan

Monitoring of time-varying reservoir properties, such as the state of stress, is a primary goal of geophysical investigations, including for geological sequestration of CO 2, enhanced hydrocarbon recovery (EOR), and other subsurface engineering activities. In this work, we used Continuous Active-Source Seismic Monitoring (CASSM), with cross-well geometry, to measure variation in seismic coda amplitude, as a consequence of effective stress change (in the form of changes in pore fluid pressure). To our knowledge, the presented results are the first in-situ example of such crosswell measurement at reservoir scale and in field conditions. Data compliment the findings of our previous workmore » which investigated the relationship between pore fluid pressure and seismic velocity (velocity-stress sensitivity) using the CASSM system at the same field site (Marchesini et al., 2017, in review). We find that P-wave coda amplitude decreases with decreasing pore pressure (increasing effective stress).« less

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

NASA Astrophysics Data System (ADS)

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

2017-10-01

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

Complete Moment Tensor Determination of Induced Seismicity in Unconventional and Conventional Oil/Gas Fields

NASA Astrophysics Data System (ADS)

Gu, C.; Li, J.; Toksoz, M. N.

2013-12-01

Induced seismicity occurs both in conventional oil/gas fields due to production and water injection and in unconventional oil/gas fields due to hydraulic fracturing. Source mechanisms of these induced earthquakes are of great importance for understanding their causes and the physics of the seismic processes in reservoirs. Previous research on the analysis of induced seismic events in conventional oil/gas fields assumed a double couple (DC) source mechanism. However, recent studies have shown a non-negligible percentage of a non-double-couple (non-DC) component of source moment tensor in hydraulic fracturing events (Šílený et al., 2009; Warpinski and Du, 2010; Song and Toksöz, 2011). In this study, we determine the full moment tensor of the induced seismicity data in a conventional oil/gas field and for hydrofrac events in an unconventional oil/gas field. Song and Toksöz (2011) developed a full waveform based complete moment tensor inversion method to investigate a non-DC source mechanism. We apply this approach to the induced seismicity data from a conventional gas field in Oman. In addition, this approach is also applied to hydrofrac microseismicity data monitored by downhole geophones in four wells in US. We compare the source mechanisms of induced seismicity in the two different types of gas fields and explain the differences in terms of physical processes.

Induced Seismicity Potential of Energy Technologies

NASA Astrophysics Data System (ADS)

Hitzman, Murray

2013-03-01

Earthquakes attributable to human activities-``induced seismic events''-have received heightened public attention in the United States over the past several years. Upon request from the U.S. Congress and the Department of Energy, the National Research Council was asked to assemble a committee of experts to examine the scale, scope, and consequences of seismicity induced during fluid injection and withdrawal associated with geothermal energy development, oil and gas development, and carbon capture and storage (CCS). The committee's report, publicly released in June 2012, indicates that induced seismicity associated with fluid injection or withdrawal is caused in most cases by change in pore fluid pressure and/or change in stress in the subsurface in the presence of faults with specific properties and orientations and a critical state of stress in the rocks. The factor that appears to have the most direct consequence in regard to induced seismicity is the net fluid balance (total balance of fluid introduced into or removed from the subsurface). Energy technology projects that are designed to maintain a balance between the amount of fluid being injected and withdrawn, such as most oil and gas development projects, appear to produce fewer seismic events than projects that do not maintain fluid balance. Major findings from the study include: (1) as presently implemented, the process of hydraulic fracturing for shale gas recovery does not pose a high risk for inducing felt seismic events; (2) injection for disposal of waste water derived from energy technologies does pose some risk for induced seismicity, but very few events have been documented over the past several decades relative to the large number of disposal wells in operation; and (3) CCS, due to the large net volumes of injected fluids suggested for future large-scale carbon storage projects, may have potential for inducing larger seismic events.

Data Quality Parameters and Web Services Facilitate User Access to Research-Ready Seismic Data

NASA Astrophysics Data System (ADS)

Trabant, C. M.; Templeton, M. E.; Van Fossen, M.; Weertman, B.; Ahern, T. K.; Casey, R. E.; Keyson, L.; Sharer, G.

2016-12-01

IRIS Data Services has the mission of providing efficient access to a wide variety of seismic and related geoscience data to the user community. With our vast archive of freely available data, we recognize that there is a constant challenge to provide data to scientists and students that are of a consistently useful level of quality. To address this issue, we began by undertaking a comprehensive survey of the data and generating metrics measurements that provide estimates of data quality. These measurements can inform the scientist of the level of suitability of a given set of data for their scientific investigation. They also serve as a quality assurance check for network operators, who can act on this information to improve their current recording or mitigate issues with already recorded data and metadata. Following this effort, IRIS Data Services is moving forward to focus on providing tools for the scientist that make it easier to access data of a quality and characteristic that suits their investigation. Data that fulfill this criterion are termed "research-ready". In addition to filtering data by type, geographic location, proximity to events, and specific time ranges, we will offer the ability to filter data based on specific quality assessments. These include signal-to-noise ratio measurements, data continuity, timing quality, absence of channel cross-talk, and potentially many other factors. Our goal is to ensure that the user receives only the data that meets their specifications and will not require extensive review and culling after delivery. We will present the latest developments of the MUSTANG automated data quality system and introduce the Research-Ready Data Sets (RRDS) service. Together these two technologies serve as a data quality assurance ecosystem that will provide benefit to the scientific community by aiding efforts to readily find appropriate and suitable data for use in any number of objectives.

Angola Seismicity MAP

NASA Astrophysics Data System (ADS)

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

Induced seismicity in Carbon and Emery counties, Utah

NASA Astrophysics Data System (ADS)

Brown, Megan R. M.

Utah is one of the top producers of oil and natural gas in the United States. Over the past 18 years, more than 4.2 billion gallons of wastewater from the petroleum industry have been injected into the Navajo Sandstone, Kayenta Formation, and Wingate Sandstone in two areas in Carbon and Emery County, Utah, where seismicity has increased during the same period. In this study, I investigated whether or not wastewater injection is related to the increased seismicity. Previous studies have attributed all of the seismicity in central Utah to coal mining activity. I found that water injection might be a more important cause. In the coal mining area, seismicity rate increased significantly 1-5 years following the commencement of wastewater injection. The increased seismicity consists almost entirely of earthquakes with magnitudes of less than 3, and is localized in areas seismically active prior to the injection. I have established the spatiotemporal correlations between the coal mining activities, the wastewater injection, and the increased seismicity. I used simple groundwater models to estimate the change in pore pressure and evaluate the observed time gap between the start of injection and the onset of the increased seismicity in the areas surrounding the injection wells. To ascertain that the increased seismicity is not fluctuation of background seismicity, I analyzed the magnitude-frequency relation of these earthquakes and found a clear increase in the b-value following the wastewater injection. I conclude that the marked increase of seismicity rate in central Utah is induced by both mining activity and wastewater injection, which raised pore pressure along pre-existing faults.

Scenarios for local seismic effects of Tulcea (Romania) crustal earthquakes, preliminary approach for the seismic microzoning of Tulcea city

NASA Astrophysics Data System (ADS)

Florin Bǎlan, Å.žTefan; Apostol, Bogdan; Chitea, F.; Anghelache, Mirela Adriana; Cioflan, Carmen O.; Serban, A.

2010-05-01

nonlinear variations of shear modulus and damping function with state of strain during the earthquakes are expected in superficial soil deposits. Also, the epicenter distributions, the isobats map and 3D image of focal distribution surface will be presented together with the focal mechanisms of the most significant earthquakes which had affected the zone. All these give us a very complete image of the crustal seismic hazard of the Tulcea zone. This study proposes itself to take in consideration only the local effects of the crustal seismic hazard from Tulcea zone, like a preliminary step for the seismic microzoning of Tulcea city. The latter is a broader research which implies the interdisciplinary work between specialists from different fields of research. Finally, by comparing the seismic microzoning map with the vulnerability distribution mapping for each building type and damage distribution maps, the general aspect of the real earthquake effects over the city is figured out. Acknowledgements: The research was performed with financial support from the CNMP within 31036/ 2007 scientific project.

Seismic imaging of post-glacial sediments - test study before Spitsbergen expedition

NASA Astrophysics Data System (ADS)

Szalas, Joanna; Grzyb, Jaroslaw; Majdanski, Mariusz

2017-04-01

This work presents results of the analysis of reflection seismic data acquired from testing area in central Poland. For this experiment we used total number of 147 vertical component seismic stations (DATA-CUBE and Reftek "Texan") with accelerated weight drop (PEG-40). The profile was 350 metres long. It is a part of pilot study for future research project on Spitsbergen. The purpose of the study is to recognise the characteristics of seismic response of post-glacial sediments in order to design the most adequate survey acquisition parameters and processing sequence for data from Spitsbergen. Multiple tests and comparisons have been performed to obtain the best possible quality of seismic image. In this research we examine the influence of receiver interval size, front mute application and surface wave attenuation attempts. Although seismic imaging is the main technique we are planning to support this analysis with additional data from traveltime tomography, MASW and other a priori information.

H-fractal seismic metamaterial with broadband low-frequency bandgaps

NASA Astrophysics Data System (ADS)

Du, Qiujiao; Zeng, Yi; Xu, Yang; Yang, Hongwu; Zeng, Zuoxun

2018-03-01

The application of metamaterial in civil engineering to achieve isolation of a building by controlling the propagation of seismic waves is a substantial challenge because seismic waves, a superposition of longitudinal and shear waves, are more complex than electromagnetic and acoustic waves. In this paper, we design a broadband seismic metamaterial based on H-shaped fractal pillars and report numerical simulation of band structures for seismic surface waves propagating. Comparative study on the band structures of H-fractal seismic metamaterials with different levels shows that a new level of fractal structure creates new band gap, widens the total band gaps and shifts the same band gap towards lower frequencies. Moreover, the vibration modes for H-fractal seismic metamaterials are computed and analyzed to clarify the mechanism of widening band gaps. A numerical investigation of seismic surface waves propagation on a 2D array of fractal unit cells on the surface of semi-infinite substrate is proposed to show the efficiency of earthquake shielding in multiple complete band gaps.

Spatial and temporal variation of seismic velocity during earthquakes and volcanic eruptions in western Japan: Insight into mechanism for seismic velocity variation

NASA Astrophysics Data System (ADS)

Tsuji, T.; Ikeda, T.; Nimiya, H.

2017-12-01

We report spatio-temporal variations of seismic velocity around the seismogenic faults in western Japan. We mainly focus on the seismic velocity variation during (1) the 2016 Off-Mie earthquake in the Nankai subduction zone (Mw5.8) and (2) the 2016 Kumamoto earthquake in Kyushu Island (Mw7.0). We applied seismic interferometry and surface wave analysis to the ambient noise data recorded by Hi-net and DONET seismometers of National Research Institute for Earth Science and Disaster Resilience (NIED). Seismic velocity near the rupture faults and volcano decreased during the earthquake. For example, we observed velocity reduction around the seismogenic Futagawa-Hinagu fault system and Mt Aso in the 2016 Kumamoto earthquake. We also identified velocity increase after the eruptions of Mt Aso. During the 2016 Off-Mie earthquake, we observed seismic velocity variation in the Nankai accretionary prism. After the earthquakes, the seismic velocity gradually returned to the pre-earthquake value. The velocity recovering process (healing process) is caused by several mechanisms, such as pore pressure reduction, strain change, and crack sealing. By showing the velocity variations obtained at different geologic settings (volcano, seismogenic fault, unconsolidated sediment), we discuss the mechanism of seismic velocity variation as well as the post-seismic fault healing process.

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

NASA Astrophysics Data System (ADS)

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

Preliminary seismic evaluation and ranking of bridges along I-24 in Western Kentucky.

DOT National Transportation Integrated Search

2006-09-01

This study represents one of the Seismic Evaluation of I-24 Bridges investigative series. The focus is on preliminary seismic evaluation and ranking of bridges according to their seismic vulnerability. Bridges along I-24 are considered in this invest...

Seismic response of a full-scale wind turbine tower using experimental and numerical modal analysis

NASA Astrophysics Data System (ADS)

Kandil, Kamel Sayed Ahmad; Saudi, Ghada N.; Eltaly, Boshra Aboul-Anen; El-khier, Mostafa Mahmoud Abo

2016-12-01

Wind turbine technology has developed tremendously over the past years. In Egypt, the Zafarana wind farm is currently generating at a capacity of 517 MW, making it one of the largest onshore wind farms in the world. It is located in an active seismic zone along the west side of the Gulf of Suez. Accordingly, seismic risk assessment is demanded for studying the structural integrity of wind towers under expected seismic hazard events. In the context of ongoing joint Egypt-US research project "Seismic Risk Assessment of Wind Turbine Towers in Zafarana wind Farm Egypt" (Project ID: 4588), this paper describes the dynamic performance investigation of an existing Nordex N43 wind turbine tower. Both experimental and numerical work are illustrated explaining the methodology adopted to investigate the dynamic behavior of the tower under seismic load. Field dynamic testing of the full-scale tower was performed using ambient vibration techniques (AVT). Both frequency domain and time domain methods were utilized to identify the actual dynamic properties of the tower as built in the site. Mainly, the natural frequencies, their corresponding mode shapes and damping ratios of the tower were successfully identified using AVT. A vibration-based finite element model (FEM) was constructed using ANSYS V.12 software. The numerical and experimental results of modal analysis were both compared for matching purpose. Using different simulation considerations, the initial FEM was updated to finally match the experimental results with good agreement. Using the final updated FEM, the response of the tower under the AQABA earthquake excitation was investigated. Time history analysis was conducted to define the seismic response of the tower in terms of the structural stresses and displacements. This work is considered as one of the pioneer structural studies of the wind turbine towers in Egypt. Identification of the actual dynamic properties of the existing tower was successfully performed

The Search for Fluid Injection-induced Seismicity in California Oilfields

NASA Astrophysics Data System (ADS)

Layland-Bachmann, C. E.; Brodsky, E. E.; Foxall, W.; Goebel, T.; Jordan, P. D.

2017-12-01

During recent years, earthquakes associated with human activity have become a matter of heightened public concern. Wastewater injection is a major concern, as seismic events with magnitudes larger than M5.5 have been linked to this practice. Much of the research in the United States is focused on the mid-continental regions, where low rates of naturally-occurring seismicity and high-volume injection activities facilitate easier identification by statistical correlation of potentially induced seismic events . However, available industry data are often limited in these regions and therefore limits our ability to connect specific human activities to earthquakes. Specifically, many previous studies have focused primarily on injection activity in single wells, ignoring the interconnectivity of production and injection in a reservoir. The situation in California differs from the central U.S. in two ways: (1) A rich dataset of oilfield activity is publically available from state agencies, which enables a more in-depth investigation of the human forcing; and (2) the identification of potential anthropogenically-induced earthquakes is complex as a result of high tectonic activity. Here we address both differences. We utilize a public database of hydrologically connected reservoirs to assess whether there are any statistically significant correlations between the net injected volumes, reservoir pressures and injection depths, and the earthquake locations and frequencies of occurrence. We introduce a framework of physical and empirical models and statistical techniques to identify potentially induced seismic events. While the aim is to apply the methods statewide, we first apply our methods in the Southern San Joaquin Valley. Although, we find an anomalously high earthquake rate in Southern Kern County oilfields, which is consistent with previous studies, we do not find a simple straightforward correlation. To successfully study induced seismicity we need a seismic catalog

78 FR 13097 - Electric Power Research Institute; Seismic Evaluation Guidance

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-26

... outcrop motion for which the soil layers above the foundation elevation have been removed. Updating the... performing soil-structure interaction analyses. Consistent with guidance described in DC/COL-ISG-017, ``Ensuring Hazard-Consistent Seismic Input for Site Response and Soil Structure Interaction Analyses,'' the...

Investigation of River Seismic Signal Induced by Sediment Transport and Water Flow: Controlled Dam Breaking Experiments

NASA Astrophysics Data System (ADS)

Chen, H. Y.; Chen, S. C.; Chao, W. A.

2015-12-01

Natural river's bedload often hard to measure, which leads numerous uncertainties for us to predict the landscape evolution. However, the measurement of bedload flux has its certain importance to estimate the river hazard. Thus, we use seismometer to receive the seismic signal induced by bedload for partially fill the gap of field measurement capabilities. Our research conducted a controlled dam breaking experiments at Landao River, Huisun Forest since it has advantage to well constraining the spatial and temporal variation of bedload transport. We set continuous bedload trap at downstream riverbed of dam to trap the transport bedload after dam breaking so as to analyze its grain size distribution and transport behavior. In the meantime we cooperate with two portable velocity seismometers (Guralp CMG6TD) along the river to explore the relationship between bedload transport and seismic signal. Bedload trap was divided into three layers, bottom, middle, and top respectively. After the experiment, we analyzed the grain size and found out the median particle size from bottom to top is 88.664mm, 129.601mm, and 214.801mm individually. The median particle size of top layer is similar with the upstream riverbed before the experiment which median particle size is 230.683mm. This phenomena indicated that as the river flow become stronger after dam breaking, the sediment size will thereupon become larger, which meant the sediment from upstream will be carried down by the water flow and turned into bedload. Furthermore, we may tell apart the seismic signal induced by water flow and bedload by means of two different position seismometers. Eventually, we may estimate the probable error band of bedload quantity via accurately control of water depth, time-lapse photography, 3D LiDAR and other hydrology parameters.

Assessing the seismic risk potential of South America

USGS Publications Warehouse

Jaiswal, Kishor; Petersen, Mark D.; Harmsen, Stephen; Smoczyk, Gregory M.

2016-01-01

We present here a simplified approach to quantifying regional seismic risk. The seismic risk for a given region can be inferred in terms of average annual loss (AAL) that represents long-term value of earthquake losses in any one year caused from a long-term seismic hazard. The AAL are commonly measured in the form of earthquake shaking-induced deaths, direct economic impacts or indirect losses caused due to loss of functionality. In the context of South American subcontinent, the analysis makes use of readily available public data on seismicity, population exposure, and the hazard and vulnerability models for the region. The seismic hazard model was derived using available seismic catalogs, fault databases, and the hazard methodologies that are analogous to the U.S. Geological Survey’s national seismic hazard mapping process. The Prompt Assessment of Global Earthquakes for Response (PAGER) system’s direct empirical vulnerability functions in terms of fatality and economic impact were used for performing exposure and risk analyses. The broad findings presented and the risk maps produced herein are preliminary, yet they do offer important insights into the underlying zones of high and low seismic risks in the South American subcontinent. A more detailed analysis of risk may be warranted by engaging local experts, especially in some of the high risk zones identified through the present investigation.

Comparative statistical and spectral studies of seismic and non-seismic sub-ionospheric VLF anomalies

NASA Astrophysics Data System (ADS)

Wolbang, Daniel; Biernat, Helfried; Schwingenschuh, Konrad; Eichelberger, Hans; Prattes, Gustav; Besser, Bruno; Boudjada, Mohammed Y.; Rozhnoi, Alexander; Solovieva, Maria; Biagi, Pier Francesco; Friedrich, Martin

2013-04-01

We present a comparative study of seismic and non-seismic sub-ionospheric VLF anomalies. Our method is based on parameter variations of the sub-ionospheric VLF waveguide formed by the surface and the lower ionosphere. The used radio links working in the frequency range between 10 and 50 kHz, the receivers are part of the European and Russian networks. Various authors investigated the lithopsheric-atmospheric-ionospheric coupling and predicted the lowering of the ionosphere over earthquake preparation zones [1]. The received nighttime signal of a sub-ionospheric waveguide depends strongly on the height of the ionospheric E-layer, typically 80 to 85 km. This height is characterized by a typical gradient of the electron density near the atmospheric-ionospheric boundary [2]. In the last years it has been turned out that one of the major issues of sub-ionospheric seismo-electromagnetic VLF studies are the non-seismic influences on the links, which have to be carefully characterized. Among others this could be traveling ionospheric disturbances, geomagnetic storms as well as electron precipitation. Our emphasis is on the analysis of daily, monthly and annual variations of the VLF amplitude. To improve the statistics we investigate the behavior and typical variations of the VLF amplitude and phase over a period of more than 2 years. One important parameter considered is the rate how often the fluctuations are falling below a significant level derived from a mean value. The temporal variations and the amplitudes of these depressions are studied for several years for sub-ionospheric VLF radio links with the receivers in Graz and Kamchatka. In order to study the difference between seismic and non-seismic turbulences in the lower ionosphere a power spectrum analysis of the received signal is performed too. We are especially interested in variations T>6 min which are typical for atmospheric gravity waves causing the lithospheric-atmospheric-ionospheric coupling [3]. All

Expected Seismicity and the Seismic Noise Environment of Europa

NASA Astrophysics Data System (ADS)

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

2018-01-01

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

The Apollo passive seismic experiment

NASA Technical Reports Server (NTRS)

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

1979-01-01

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coleman, Justin

2015-02-01

) structure. Figure 1: Project activities The study will consider a representative NPP reinforced concrete reactor building and representative plant safety system. This study will leverage existing research and development (R&D) activities at INL. Figure 1 shows the proposed study steps with the steps in blue representing activities already funded at INL and the steps in purple the activities that would be funded under this proposal. The following results will be documented: 1) Comparison of seismic risk for the non-seismically isolated (non-SI) and seismically isolated (SI) NPP, and 2) an estimate of construction cost savings when implementing SI at the site of the generic NPP.« less

Cavity Detection and Delineation Research. Report 2. Seismic Methodology: Medford Cave Site, Florida.

DTIC Science & Technology

1983-06-01

energy. A distance of 50 ft was maintained between source and detector for one test and 25 ft for the other tests. Since the seismic unit was capable...during the tests. After a recording was made, the seismic source and geophone were each moved 5 ft, thus maintaining the 50- or 25-ft source-to- detector ...produced by cavities; therefore, detection using this technique was not achieved. The sensitivity of the uphole refraction method to the presence of

A critical review of the potential impacts of marine seismic surveys on fish & invertebrates.

PubMed

Carroll, A G; Przeslawski, R; Duncan, A; Gunning, M; Bruce, B

2017-01-15

Marine seismic surveys produce high intensity, low-frequency impulsive sounds at regular intervals, with most sound produced between 10 and 300Hz. Offshore seismic surveys have long been considered to be disruptive to fisheries, but there are few ecological studies that target commercially important species, particularly invertebrates. This review aims to summarise scientific studies investigating the impacts of low-frequency sound on marine fish and invertebrates, as well as to critically evaluate how such studies may apply to field populations exposed to seismic operations. We focus on marine seismic surveys due to their associated unique sound properties (i.e. acute, low-frequency, mobile source locations), as well as fish and invertebrates due to the commercial value of many species in these groups. The main challenges of seismic impact research are the translation of laboratory results to field populations over a range of sound exposure scenarios and the lack of sound exposure standardisation which hinders the identification of response thresholds. An integrated multidisciplinary approach to manipulative and in situ studies is the most effective way to establish impact thresholds in the context of realistic exposure levels, but if that is not practical the limitations of each approach must be carefully considered. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

A quantitative analysis of global intermediate and deep seismicity

NASA Astrophysics Data System (ADS)

Ruscic, Marija; Becker, Dirk; Le Pourhiet, Laetitita; Agard, Philippe; Meier, Thomas

2017-04-01

The seismic activity in subduction zones around the world shows a large spatial variabilty with some regions exhibiting strong seismic activity down to depths of almost 700km while in other places seismicity terminates at depths of about 200 or 300 km. Also the decay of the number of seismic events or of the seismic moment with depth is more pronounced in some regions than in others. The same is true for the variability of the ratio of large to small events (the b-value of the Gutenberg-Richter relation) that is varying with depth. These observations are often linked to parameters of the downgoing plate like age or subduction velocity. In this study we investigate a subset of subduction zones utilizing the revised ISC catalogue of intermediate and deep seismicity to determine statistical parameters well suited to describe properties of intermediate deep and deep events. The seismicity is separated into three depth intervals from 50-175km, 175-400km and >400km based on the depth at which the plate contact decouples, the observed nearly exponential decay of the event rate with depth and the supposed depth of phase transition at 410 km depth where also an increase of the event number with depth is observed. For estimation of the b-value and the exponential decay with depth, a restriction of the investigated time interval to the period after 1997 produced significantly better results indicating a globally homogeneous magnitude scale with the magnitude of completeness of about Mw 5. On a global scale the b-value decreases with depth from values of about 1 at 50-175km to values of slightly below 0.8 for events below 400km. Also, there is a slight increase of the b-value with the age of the subducting plate. These changes in the b-value with depth and with age may indicate a varying fragmentation of the slab. With respect to the ratio of the seismic moment between deeper and shallower parts of the subduction zones a dependence on the age is apparent with older slabs

Seismic tomography for charaterization of an ore vein in the research and education mine Reiche Zeche

NASA Astrophysics Data System (ADS)

Winter, Sebastian; Schlüter, Ralf; Hlousek, Felix; Buske, Stefan

2017-04-01

A test site for the design, implementation and operation of an underground in-situ bioleaching unit has been installed by the „Biohydrometallurgical Center for Strategic Elements" at the research and education mine "Reiche Zeche" of Technical University Bergakademie Freiberg. For this purpose an ore vein block will be developed and mined with the bio-hydrometallurgical in-situ leaching technology. As a site survey an underground seismic tomography experiment has been performed to investigate the spatial distribution of the ore vein within this block consisting mainly of gneiss and with dimensions of about 30 x 10 meters. The experiment was performed with a sledgehammer as source and 76 three-component receivers with source and receiver point intervals of about 1 m surrounding the approximately rectangular block. High precision laser scanning was performed to obtain accurate source and receiver positions which was particularly necessary to obtain reliable results due to the generally high wave velocities of the gneiss. The resulting seismic data set showed a high signal-to-noise ratio with clear first arrivals which were picked for all source and receiver combinations and subsequently used as input to a first-arrival tomographic inversion scheme. The resulting velocity model has very good ray coverage and shows well resolved high- and low-velocity regions within the block. These regions can be clearly assigned to mapped outcrops of the ore vein along the galleries surrounding the block, including a correlation of low velocities to fractured rock parts as well as high velocities to the undisturbed ore vein core, respectively. In summary the obtained velocity model and the inferred spatial distribution of the ore vein provides a good basis for planning and implementing the actual ore mining step using the envisaged bioleaching technology.

Detecting Seismic Activity with a Covariance Matrix Analysis of Data Recorded on Seismic Arrays

NASA Astrophysics Data System (ADS)

Seydoux, L.; Shapiro, N.; de Rosny, J.; Brenguier, F.

2014-12-01

Modern seismic networks are recording the ground motion continuously all around the word, with very broadband and high-sensitivity sensors. The aim of our study is to apply statistical array-based approaches to processing of these records. We use the methods mainly brought from the random matrix theory in order to give a statistical description of seismic wavefields recorded at the Earth's surface. We estimate the array covariance matrix and explore the distribution of its eigenvalues that contains information about the coherency of the sources that generated the studied wavefields. With this approach, we can make distinctions between the signals generated by isolated deterministic sources and the "random" ambient noise. We design an algorithm that uses the distribution of the array covariance matrix eigenvalues to detect signals corresponding to coherent seismic events. We investigate the detection capacity of our methods at different scales and in different frequency ranges by applying it to the records of two networks: (1) the seismic monitoring network operating on the Piton de la Fournaise volcano at La Réunion island composed of 21 receivers and with an aperture of ~15 km, and (2) the transportable component of the USArray composed of ~400 receivers with ~70 km inter-station spacing.

Evaluation of induced seismicity forecast models in the Induced Seismicity Test Bench

NASA Astrophysics Data System (ADS)

Király, Eszter; Gischig, Valentin; Zechar, Jeremy; Doetsch, Joseph; Karvounis, Dimitrios; Wiemer, Stefan

2016-04-01

Induced earthquakes often accompany fluid injection, and the seismic hazard they pose threatens various underground engineering projects. Models to monitor and control induced seismic hazard with traffic light systems should be probabilistic, forward-looking, and updated as new data arrive. Here, we propose an Induced Seismicity Test Bench to test and rank such models. We apply the test bench to data from the Basel 2006 and Soultz-sous-Forêts 2004 geothermal stimulation projects, and we assess forecasts from two models that incorporate a different mix of physical understanding and stochastic representation of the induced sequences: Shapiro in Space (SiS) and Hydraulics and Seismics (HySei). SiS is based on three pillars: the seismicity rate is computed with help of the seismogenic index and a simple exponential decay of the seismicity; the magnitude distribution follows the Gutenberg-Richter relation; and seismicity is distributed in space based on smoothing seismicity during the learning period with 3D Gaussian kernels. The HySei model describes seismicity triggered by pressure diffusion with irreversible permeability enhancement. Our results show that neither model is fully superior to the other. HySei forecasts the seismicity rate well, but is only mediocre at forecasting the spatial distribution. On the other hand, SiS forecasts the spatial distribution well but not the seismicity rate. The shut-in phase is a difficult moment for both models in both reservoirs: the models tend to underpredict the seismicity rate around, and shortly after, shut-in. Ensemble models that combine HySei's rate forecast with SiS's spatial forecast outperform each individual model.

Implications from palaeoseismological investigations at the Markgrafneusiedl Fault (Vienna Basin, Austria) for seismic hazard assessment

NASA Astrophysics Data System (ADS)

Hintersberger, Esther; Decker, Kurt; Lomax, Johanna; Lüthgens, Christopher

2018-02-01

Intraplate regions characterized by low rates of seismicity are challenging for seismic hazard assessment, mainly for two reasons. Firstly, evaluation of historic earthquake catalogues may not reveal all active faults that contribute to regional seismic hazard. Secondly, slip rate determination is limited by sparse geomorphic preservation of slowly moving faults. In the Vienna Basin (Austria), moderate historical seismicity (Imax, obs / Mmax, obs = 8/5.2) concentrates along the left-lateral strike-slip Vienna Basin Transfer Fault (VBTF). In contrast, several normal faults branching out from the VBTF show neither historical nor instrumental earthquake records, although geomorphological data indicate Quaternary displacement along those faults. Here, located about 15 km outside of Vienna, the Austrian capital, we present a palaeoseismological dataset of three trenches that cross one of these splay faults, the Markgrafneusiedl Fault (MF), in order to evaluate its seismic potential. Comparing the observations of the different trenches, we found evidence for five to six surface-breaking earthquakes during the last 120 kyr, with the youngest event occurring at around 14 ka. The derived surface displacements lead to magnitude estimates ranging between 6.2 ± 0.5 and 6.8 ± 0.4. Data can be interpreted by two possible slip models, with slip model 1 showing more regular recurrence intervals of about 20-25 kyr between the earthquakes with M ≥ 6.5 and slip model 2 indicating that such earthquakes cluster in two time intervals in the last 120 kyr. Direct correlation between trenches favours slip model 2 as the more plausible option. Trench observations also show that structural and sedimentological records of strong earthquakes with small surface offset have only low preservation potential. Therefore, the earthquake frequency for magnitudes between 6 and 6.5 cannot be constrained by the trenching records. Vertical slip rates of 0

Inferring crustal viscosity from seismic velocity: Application to the lower crust of Southern California

NASA Astrophysics Data System (ADS)

Shinevar, William J.; Behn, Mark D.; Hirth, Greg; Jagoutz, Oliver

2018-07-01

We investigate the role of composition on the viscosity of the lower crust through a joint inversion of seismic P-wave (Vp) and S-wave (Vs) velocities. We determine the efficacy of using seismic velocity to constrain viscosity, extending previous research demonstrating robust relationships between seismic velocity and crustal composition, as well as crustal composition and viscosity. First, we calculate equilibrium mineral assemblages and seismic velocities for a global compilation of crustal rocks at relevant pressures and temperatures. Second, we use a rheological mixing model that incorporates single-phase flow laws for major crust-forming minerals to calculate aggregate viscosity from predicted mineral assemblages. We find a robust correlation between crustal viscosity and Vp together with Vs in the α-quartz regime. Using seismic data, geodetic surface strain rates, and heat flow measurements from Southern California, our method predicts that lower crustal viscosity varies regionally by four orders of magnitude, and lower crustal stress varies by three orders of magnitude at 25 km depth. At least half of the total variability in stress can be attributed to composition, implying that regional lithology has a significant effect on lower crustal geodynamics. Finally, we use our method to predict the depth of the brittle-ductile transition and compare this to regional variations of the seismic-aseismic transition. The variations in the seismic-aseismic transition are not explained by the variations in our model rheology inferred from the geophysical observations. Thus, we conclude that fabric development, in conjunction with compositional variations (i.e., quartz and mica content), is required to explain the regional changes in the seismic-aseismic transition.

Characterising Seismicity at Alutu, an Actively Deforming Volcano in the Main Ethiopian Rift

NASA Astrophysics Data System (ADS)

Wilks, M.; Nowacki, A.; Kendall, J. M.; Wookey, J. M.; Biggs, J.; Bastow, I. D.; Ayele, A.; Bedada, T.

2013-12-01

The Main Ethiopian Rift (MER) provides a unique example of the tectonic and volcanic processes occuring during the transition from continental rifting to oceanic spreading. Situated 100 km south of Addis Ababa along the eastern rift margin, Alutu is a silicic stratovolcano that geodetic measurements (InSAR and GPS) have shown is actively deforming. Though the volcano has received relatively little scientific attention it is also a site of economic significance as a geothermal power plant resides within the caldera. As part of ARGOS (Alutu Research Geophysical ObservationS), a multi-disciplinary project aiming to investigate the magmatic and hydrothermal processes occuring at Alutu, a seismic network of 12 broadband seismometers was deployed in January 2012. Other components of ARGOS include InSAR, GPS, geologic mapping and magnetotellurics. From the seismic dataset, P- and S-wave arrivals across the array were manually picked and used to locate events using a non-linear earthquake location algorithm (NonLinLoc) and a predefined 1D velocity model. Perturbations were later applied to this velocity model to investigate the sensitivity of the locations and evaluate the true uncertainties of the solutions. Over 1000 events were successfully located during 2012, where picks were possible at 4 or more stations. Seismicity clusters at both shallow depths (z<2 km) beneath the caldera and at deeper depths of 5-15 km. There is a significant increase in seismicity during the rainy months, suggesting the shallow events may be related to the hydrothermal system. We interpret the deeper events as being magmatic in origin. Events are also located along the eastern border faults that bound the outer edges of the MER and highlights that seismicity arises concurrently via tectonic processes. An adapted version of Richter's original local magnitude scale (ML) to account for attenuation within the MER (Keir et al., 2006) was then used to compute magnitudes for the best located events

Rippability Assessment of Weathered Sedimentary Rock Mass using Seismic Refraction Methods

NASA Astrophysics Data System (ADS)

Ismail, M. A. M.; Kumar, N. S.; Abidin, M. H. Z.; Madun, A.

2018-04-01

Rippability or ease of excavation in sedimentary rocks is a significant aspect of the preliminary work of any civil engineering project. Rippability assessment was performed in this study to select an available ripping machine to rip off earth materials using the seismic velocity chart provided by Caterpillar. The research area is located at the proposed construction site for the development of a water reservoir and related infrastructure in Kampus Pauh Putra, Universiti Malaysia Perlis. The research was aimed at obtaining seismic velocity, P-wave (Vp) using a seismic refraction method to produce a 2D tomography model. A 2D seismic model was used to delineate the layers into the velocity profile. The conventional geotechnical method of using a borehole was integrated with the seismic velocity method to provide appropriate correlation. The correlated data can be used to categorize machineries for excavation activities based on the available systematic analysis procedure to predict rock rippability. The seismic velocity profile obtained was used to interpret rock layers within the ranges labelled as rippable, marginal, and non-rippable. Based on the seismic velocity method the site can be classified into loose sand stone to moderately weathered rock. Laboratory test results shows that the site’s rock material falls between low strength and high strength. Results suggest that Caterpillar’s smallest ripper, namely, D8R, can successfully excavate materials based on the test results integration from seismic velocity method and laboratory test.

Mass Wasting on the Moon: Implications for Seismicity

NASA Technical Reports Server (NTRS)

Weber, Renee; Nahm, Amanda; Schmerr, Nick; Yanites, Brian

2016-01-01

Seismicity estimates play an important role in creating regional geological characterizations, which are useful for understanding a planet's formation and evolution, and are of key importance to site selection for landed missions. Here we investigate the regional effects of seismicity in planetary environments with the goal of determining whether such surface features on the Moon, could be triggered by fault motion.

Mass Wasting on the Moon: Implications for Seismicity

NASA Technical Reports Server (NTRS)

Weber, R. C.; Nahm, A. L.; Yanites, B.; Schmerr, N.

2016-01-01

Introduction: Seismicity estimates play an important role in creating regional geological characterizations, which are useful for understanding a planet's formation and evolution, and of key importance to site selection for landed missions. Here we investigate the regional effects of lunar seismicity with the goal of determining whether surface features such as landslides and boulder trails on the Moon are triggered by fault motion.

Geophysical investigations in Jordan

NASA Astrophysics Data System (ADS)

Kovach, Robert L.; Andreasen, Gordon E.; Gettings, Mark E.; El-Kaysi, Kays

1990-08-01

A number of geophysical investigations have been undertaken in the Hashemite Kingdom of Jordan to provide data for understanding the tectonic framework, the pattern of seismicity, earthquake hazards and geothermal resources of the country. Both the historical seismic record and the observed recent seismicity point to the dominance of the Dead Sea Rift as the main locus of seismic activity but significant branching trends and gaps in the seismicity pattern are also seen. A wide variety of focal plane solutions are observed emphasizing the complex pattern of fault activity in the vicinity of the rift zone. Geophysical investigations directed towards the geothermal assessment of the prominent thermal springs of Zerga Ma'in and Zara are not supportive of the presence of a crustal magmatic source.

Geophysical investigations in Jordan

USGS Publications Warehouse

Kovach, R.L.; Andreasen, G.E.; Gettings, M.E.; El-Kaysi, K.

1990-01-01

A number of geophysical investigations have been undertaken in the Hashemite Kingdom of Jordan to provide data for understanding the tectonic framework, the pattern of seismicity, earthquake hazards and geothermal resources of the country. Both the historical seismic record and the observed recent seismicity point to the dominance of the Dead Sea Rift as the main locus of seismic activity but significant branching trends and gaps in the seismicity pattern are also seen. A wide variety of focal plane solutions are observed emphasizing the complex pattern of fault activity in the vicinity of the rift zone. Geophysical investigations directed towards the geothermal assessment of the prominent thermal springs of Zerga Ma'in and Zara are not supportive of the presence of a crustal magmatic source. ?? 1990.

Gas and seismicity within the Istanbul seismic gap.

PubMed

Géli, L; Henry, P; Grall, C; Tary, J-B; Lomax, A; Batsi, E; Riboulot, V; Cros, E; Gürbüz, C; Işık, S E; Sengör, A M C; Le Pichon, X; Ruffine, L; Dupré, S; Thomas, Y; Kalafat, D; Bayrakci, G; Coutellier, Q; Regnier, T; Westbrook, G; Saritas, H; Çifçi, G; Çağatay, M N; Özeren, M S; Görür, N; Tryon, M; Bohnhoff, M; Gasperini, L; Klingelhoefer, F; Scalabrin, C; Augustin, J-M; Embriaco, D; Marinaro, G; Frugoni, F; Monna, S; Etiope, G; Favali, P; Bécel, A

2018-05-01

Understanding micro-seismicity is a critical question for earthquake hazard assessment. Since the devastating earthquakes of Izmit and Duzce in 1999, the seismicity along the submerged section of North Anatolian Fault within the Sea of Marmara (comprising the "Istanbul seismic gap") has been extensively studied in order to infer its mechanical behaviour (creeping vs locked). So far, the seismicity has been interpreted only in terms of being tectonic-driven, although the Main Marmara Fault (MMF) is known to strike across multiple hydrocarbon gas sources. Here, we show that a large number of the aftershocks that followed the M 5.1 earthquake of July, 25 th 2011 in the western Sea of Marmara, occurred within a zone of gas overpressuring in the 1.5-5 km depth range, from where pressurized gas is expected to migrate along the MMF, up to the surface sediment layers. Hence, gas-related processes should also be considered for a complete interpretation of the micro-seismicity (~M < 3) within the Istanbul offshore domain.

Probabilistic Seismic Hazard Analysis for Georgia

NASA Astrophysics Data System (ADS)

Tsereteli, N. S.; Varazanashvili, O.; Sharia, T.; Arabidze, V.; Tibaldi, A.; Bonali, F. L. L.; Russo, E.; Pasquaré Mariotto, F.

2017-12-01

Nowadays, seismic hazard studies are developed in terms of the calculation of Peak Ground Acceleration (PGA), Spectral Acceleration (SA), Peak Ground Velocity (PGV) and other recorded parameters. In the frame of EMME project PSH were calculated for Georgia using GMPE based on selection criteria. In the frame of Project N 216758 (supported by Shota Rustaveli National Science Foundation (SRNF)) PSH maps were estimated using hybrid- empirical ground motion prediction equation developed for Georgia. Due to the paucity of seismically recorded information, in this work we focused our research on a more robust dataset related to macroseismic data,and attempted to calculate the probabilistic seismic hazard directly in terms of macroseismicintensity. For this reason, we started calculating new intensity prediction equations (IPEs)for Georgia taking into account different sets, belonging to the same new database, as well as distances from the seismic source.With respect to the seismic source, in order to improve the quality of the results, we have also hypothesized the size of faults from empirical relations, and calculated new IPEs also by considering Joyner-Boore and rupture distances in addition to epicentral and hypocentral distances. Finally, site conditions have been included as variables for IPEs calculation Regarding the database, we used a brand new revised set of macroseismic data and instrumental records for the significant earthquakes that struck Georgia between 1900 and 2002.Particularly, a large amount of research and documents related to macroseismic effects of individual earthquakes, stored in the archives of the Institute of Geophysics, were used as sources for the new macroseismic data. The latter are reported in the Medvedev-Sponheuer-Karnikmacroseismic scale (MSK64). For each earthquake the magnitude, the focal depth and the epicenter location are also reported. An online version of the database, with therelated metadata,has been produced for the 69

Seismic Catalogue and Seismic Network in Haiti

NASA Astrophysics Data System (ADS)

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

2013-05-01

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

Spectral Decomposition and Other Seismic Attributes for Gas Hydrate Prospecting

DOE Office of Scientific and Technical Information (OSTI.GOV)

McConnell, Dan

Studying the sediments at the base of gas hydrate stability is ideal for determining the seismic response to gas hydrate saturation. First, assuming gas migration to the shallow section, this area is more likely to have concentrated gas hydrate because it encompasses the zone in which upward moving buoyant gas transitions to form immobile gas hydrate deposits. Second, this zone is interesting because these areas have the potential to show a hydrate filled zone and a gas filled zone within the same sediments. Third, the fundamental measurement within seismic data is impedance contrasts between velocity*density layers. High saturation gas hydratesmore » and free gas inhabit opposite ends of these measurements making the study of this zone ideal for investigating the seismic characteristics of gas hydrate and, hence, the investigation of other seismic attributes that may indicate gas hydrate fill.« less

Space geodetic investigation of the co- and post-seismic deformation due to the 2003 Mw7.3 Altai (Russia) earthquake: Implications for the local lithospheric rheology

NASA Astrophysics Data System (ADS)

Hamiel, Y.; Barbot, S.; Fialko, Y.

2006-12-01

We use ENVISAT Advanced Synthetic Aperture Radar data and SPOT optical imagery to investigate the co- seismic and post-seismic deformation due to the September 27th 2003, Mw7.3 Altai earthquake that occurred in the Chuya Basin area near the Russia-China-Mongolia border. Based on the SAR and SPOT data we determined the location of the ruptured fault trace and developed a co-seismic slip model for the Altai earthquake. The geodetic moment from our slip model was found to be consistent with the seismic moment determined from the teleseismic data. While the epicentral area of the Altai earthquake is not optimal for radar interferometry (in particular, due to temporal decorrelation), we were able to detect the post-seismic relaxation signal over a time period of 2.5 years following the earthquake. The signal is robust in that it allows us to discriminate between several commonly considered mechanisms of post-seismic relaxation. We find that the post-earthquake InSAR data do not warrant poro-elastic rebound in the upper crust, or simple Maxwellian visco-elastic relaxation in the upper mantle. The data can be explained in terms of afterslip on a downdip extension of the earthquake rupture, non-linear visco-elastic rheology of the ductile substrate (kinematically, similar to afterslip at early stages of relaxation), or the bulk visco-elastic relaxation in the lower crust. Continued InSAR observations may further constrain the mechanisms driving the post-seismic relaxation. The observed post-seismic deformation due to the Altai earthquake is qualitatively different from deformation due to other similar-size earthquakes (in particular, the Landers and Hector Mine earthquakes in the Mojave desert, southern California). These variations in the deformation pattern may be indicative of different rheologic structure of the continental lithosphere in different tectonically active areas.

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

NASA Astrophysics Data System (ADS)

Lyubushin, Alexey

2013-04-01

region of Nankai Trough. The analysis of seismic noise after March 2011 indicates increasing of probability of the 2nd mega-earthquake starting from the middle of 2013 within the region of Nankai Trough which remains to be SSD. References 1. Lyubushin A. Multifractal Parameters of Low-Frequency Microseisms // V. de Rubeis et al. (eds.), Synchronization and Triggering: from Fracture to Earthquake Processes, GeoPlanet: Earth and Planetary Sciences 1, DOI 10.1007/978-3-642-12300-9_15, Springer-Verlag Berlin Heidelberg, 2010, 388p., Chapter 15, pp.253-272. http://www.springerlink.com/content/hj2l211577533261/ 2. Lyubushin A.A. Synchronization of multifractal parameters of regional and global low-frequency microseisms - European Geosciences Union General Assembly 2010, Vienna, 02-07 of May, 2010, Geophysical Research Abstracts, Vol. 12, EGU2010-696, 2010. http://meetingorganizer.copernicus.org/EGU2010/EGU2010-696.pdf 3. Lyubushin A.A. Synchronization phenomena of low-frequency microseisms. European Seismological Commission, 32nd General Assembly, September 06-10, 2010, Montpelier, France. Book of abstracts, p.124, session ES6. http://alexeylyubushin.narod.ru/ESC-2010_Book_of_abstracts.pdf 4. Lyubushin A.A. Seismic Catastrophe in Japan on March 11, 2011: Long-Term Prediction on the Basis of Low-Frequency Microseisms - Izvestiya, Atmospheric and Oceanic Physics, 2011, Vol. 46, No. 8, pp. 904-921. http://www.springerlink.com/content/kq53j2667024w715/ 5. Lyubushin, A. Prognostic properties of low-frequency seismic noise. Natural Science, 4, 659-666.doi: 10.4236/ns.2012.428087. http://www.scirp.org/journal/PaperInformation.aspx?paperID=21656

The ISC Seismic Event Bibliography

NASA Astrophysics Data System (ADS)

Di Giacomo, Domenico; Storchak, Dmitry

2015-04-01

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

A Community Seismic Experiment in the ENAM Primary Site

NASA Astrophysics Data System (ADS)

Van Avendonk, H. J.

2012-12-01

Eastern North America (ENAM) was chosen as a GeoPRISMS Rift Initiation and Evolution primary site because it represents a mature continental margin with onshore and offshore rift basins in which the record of extension and continental break-up is preserved. The degree to which syn-rift magmatism and preexisting lithospheric weaknesses controlled the evolution of the margin can be further investigated if we image its 3-D structure at small and large length scales with active-source and earthquake seismic imaging. In the Summer of 2012 we submitted a proposal to the US National Science Foundation for an ambitious plan for data acquisition on a 400 km wide section of the mid-Atlantic East Coast margin around Cape Hatteras, from unextended continental lithosphere onshore to mature oceanic lithosphere offshore. This area includes an important along-strike transition in the morphology of the margin from the Carolina Trough to the Baltimore Canyon Trough, and two major fracture zones that are associated with significant offsets at the modern Mid-Atlantic Ridge. The study area also covers several features representing the post-rift modification of the margin by slope instability and fluid flow. As the Earthscope Transportable Array reaches the East Coast of the US in 2013 and 2014, we will have an unprecedented opportunity to image the detailed structure of the rifted margin. To make effective use of the research infrastructure, including the seismic vessel R/V Marcus Langseth, the Earthscope seismic instrumentation, and US OBS Instrument Pool, we propose to collect a suite of seismic data at the mid-Atlantic margin in the context of a community-driven experiment with completely open data access. This multi-faceted seismic experiment offers an immense opportunity for education of young scientists. We propose an integrated education effort during and after acquisition. The science and field parties for data acquisition will largely consist of young scientists, who will be

Discriminating Induced-Microearthquakes Using New Seismic Features

NASA Astrophysics Data System (ADS)

Mousavi, S. M.; Horton, S.

2016-12-01

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

Building an educational seismic network in Romanian schools

NASA Astrophysics Data System (ADS)

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

Development of seismic tomography software for hybrid supercomputers

NASA Astrophysics Data System (ADS)

Nikitin, Alexandr; Serdyukov, Alexandr; Duchkov, Anton

2015-04-01

Seismic tomography is a technique used for computing velocity model of geologic structure from first arrival travel times of seismic waves. The technique is used in processing of regional and global seismic data, in seismic exploration for prospecting and exploration of mineral and hydrocarbon deposits, and in seismic engineering for monitoring the condition of engineering structures and the surrounding host medium. As a consequence of development of seismic monitoring systems and increasing volume of seismic data, there is a growing need for new, more effective computational algorithms for use in seismic tomography applications with improved performance, accuracy and resolution. To achieve this goal, it is necessary to use modern high performance computing systems, such as supercomputers with hybrid architecture that use not only CPUs, but also accelerators and co-processors for computation. The goal of this research is the development of parallel seismic tomography algorithms and software package for such systems, to be used in processing of large volumes of seismic data (hundreds of gigabytes and more). These algorithms and software package will be optimized for the most common computing devices used in modern hybrid supercomputers, such as Intel Xeon CPUs, NVIDIA Tesla accelerators and Intel Xeon Phi co-processors. In this work, the following general scheme of seismic tomography is utilized. Using the eikonal equation solver, arrival times of seismic waves are computed based on assumed velocity model of geologic structure being analyzed. In order to solve the linearized inverse problem, tomographic matrix is computed that connects model adjustments with travel time residuals, and the resulting system of linear equations is regularized and solved to adjust the model. The effectiveness of parallel implementations of existing algorithms on target architectures is considered. During the first stage of this work, algorithms were developed for execution on

Analysis and Simulation of Far-Field Seismic Data from the Source Physics Experiment

DTIC Science & Technology

2012-09-01

ANALYSIS AND SIMULATION OF FAR-FIELD SEISMIC DATA FROM THE SOURCE PHYSICS EXPERIMENT Arben Pitarka, Robert J. Mellors, Arthur J. Rodgers, Sean...Security Site (NNSS) provides new data for investigating the excitation and propagation of seismic waves generated by buried explosions. A particular... seismic model. The 3D seismic model includes surface topography. It is based on regional geological data, with material properties constrained by shallow

Seismic gradiometry using ambient seismic noise in an anisotropic Earth

NASA Astrophysics Data System (ADS)

de Ridder, S. A. L.; Curtis, A.

2017-05-01

We introduce a wavefield gradiometry technique to estimate both isotropic and anisotropic local medium characteristics from short recordings of seismic signals by inverting a wave equation. The method exploits the information in the spatial gradients of a seismic wavefield that are calculated using dense deployments of seismic arrays. The application of the method uses the surface wave energy in the ambient seismic field. To estimate isotropic and anisotropic medium properties we invert an elliptically anisotropic wave equation. The spatial derivatives of the recorded wavefield are evaluated by calculating finite differences over nearby recordings, which introduces a systematic anisotropic error. A two-step approach corrects this error: finite difference stencils are first calibrated, then the output of the wave-equation inversion is corrected using the linearized impulse response to the inverted velocity anomaly. We test the procedure on ambient seismic noise recorded in a large and dense ocean bottom cable array installed over Ekofisk field. The estimated azimuthal anisotropy forms a circular geometry around the production-induced subsidence bowl. This conforms with results from studies employing controlled sources, and with interferometry correlating long records of seismic noise. Yet in this example, the results were obtained using only a few minutes of ambient seismic noise.

Urban seismic risk assessment: statistical repair cost data and probable structural losses based on damage scenario—correlation analysis

NASA Astrophysics Data System (ADS)

Eleftheriadou, Anastasia K.; Baltzopoulou, Aikaterini D.; Karabinis, Athanasios I.

2016-06-01

The current seismic risk assessment is based on two discrete approaches, actual and probable, validating afterwards the produced results. In the first part of this research, the seismic risk is evaluated from the available data regarding the mean statistical repair/strengthening or replacement cost for the total number of damaged structures (180,427 buildings) after the 7/9/1999 Parnitha (Athens) earthquake. The actual evaluated seismic risk is afterwards compared to the estimated probable structural losses, which is presented in the second part of the paper, based on a damage scenario in the referring earthquake. The applied damage scenario is based on recently developed damage probability matrices (DPMs) from Athens (Greece) damage database. The seismic risk estimation refers to 750,085 buildings situated in the extended urban region of Athens. The building exposure is categorized in five typical structural types and represents 18.80 % of the entire building stock in Greece. The last information is provided by the National Statistics Service of Greece (NSSG) according to the 2000-2001 census. The seismic input is characterized by the ratio, a g/ a o, where a g is the regional peak ground acceleration (PGA) which is evaluated from the earlier estimated research macroseismic intensities, and a o is the PGA according to the hazard map of the 2003 Greek Seismic Code. Finally, the collected investigated financial data derived from different National Services responsible for the post-earthquake crisis management concerning the repair/strengthening or replacement costs or other categories of costs for the rehabilitation of earthquake victims (construction and function of settlements for earthquake homeless, rent supports, demolitions, shorings) are used to determine the final total seismic risk factor.

The social psychology of seismic hazard adjustment: re-evaluating the international literature

NASA Astrophysics Data System (ADS)

Solberg, C.; Rossetto, T.; Joffe, H.

2010-08-01

The majority of people at risk from earthquakes do little or nothing to reduce their vulnerability. Over the past 40 years social scientists have tried to predict and explain levels of seismic hazard adjustment using models from behavioural sciences such as psychology. The present paper is the first to synthesise the major findings from the international literature on psychological correlates and causes of seismic adjustment at the level of the individual and the household. It starts by reviewing research on seismic risk perception. Next, it looks at norms and normative beliefs, focusing particularly on issues of earthquake protection responsibility and trust between risk stakeholders. It then considers research on attitudes towards seismic adjustment attributes, specifically beliefs about efficacy, control and fate. It concludes that an updated model of seismic adjustment must give the issues of norms, trust, power and identity a more prominent role. These have been only sparsely represented in the social psychological literature to date.

Investigation of upper mantle seismic discontinuities beneath the Indian Ocean using array seismology methods

NASA Astrophysics Data System (ADS)

van Driel, J.; Reiss, A. S.; Thomas, C.

2016-12-01

The topography of upper mantle seismic discontinuities can be used to constrain regional variations in composition and temperature of the Earths mantle. The 410 km discontinuity is caused by the solid-solid phase transition from olivine to wadsleyite. Due to its positive Clapeyron slope, the discontinuity is depressed in hot regimes. The phase transition from ringwoodite to bridgemanite and magnesiowüstite in contrast has a negative Clapeyron slope and therefore is elevated when hot material is present. Cold material is expected to yield an opposing topographic signature, culminating in an elevated 410 km and a depressed 660 km discontinuity. As part of the RHUM-RUM project (Réunion Hotspot and Upper Mantle - Réunions Unterer Mantel) we extract relevant geophysical parameters, by investigating the properties of upper mantle seismic discontinuities beneath the Indian Ocean. The topography of the 410 and 660 km discontinuities, which define the upper and lower bounds of the mantle transition zone, have been mapped using PP and SS underside reflections. This study has utilised over 8500 events with Mw ≥ 5.8, distributed over the entire Indian Ocean. Our robust data set yields a dense coverage of points, which are defined by consistently crossing ray paths. Array seismology methods, such as vespagrams and slowness-backazimuth analysis, are used to enhance the signal-to-noise-ratio and detect and identify weak precursor signals. The differential travel times are corrected for crustal features and converted into depth values of the discontinuities by comparing the measured travel times with theoretical ones derived from ray tracing through the 1D reference Earth model ak135. A `travel-time' stacking method has also been applied for 4° radius bins around each of the bounce points. The addition of a secondary method derives greater stability of our results and allows an enhanced error analysis procedure. In order to better constrain the mineralogical processes taking

Exposure to seismic survey alters blue whale acoustic communication

PubMed Central

Di Iorio, Lucia; Clark, Christopher W.

2010-01-01

The ability to perceive biologically important sounds is critical to marine mammals, and acoustic disturbance through human-generated noise can interfere with their natural functions. Sounds from seismic surveys are intense and have peak frequency bands overlapping those used by baleen whales, but evidence of interference with baleen whale acoustic communication is sparse. Here we investigated whether blue whales (Balaenoptera musculus) changed their vocal behaviour during a seismic survey that deployed a low-medium power technology (sparker). We found that blue whales called consistently more on seismic exploration days than on non-exploration days as well as during periods within a seismic survey day when the sparker was operating. This increase was observed for the discrete, audible calls that are emitted during social encounters and feeding. This response presumably represents a compensatory behaviour to the elevated ambient noise from seismic survey operations. PMID:19776059

Impact of magnitude uncertainties on seismic catalogue properties

NASA Astrophysics Data System (ADS)

Leptokaropoulos, K. M.; Adamaki, A. K.; Roberts, R. G.; Gkarlaouni, C. G.; Paradisopoulou, P. M.

2018-05-01

Catalogue-based studies are of central importance in seismological research, to investigate the temporal, spatial and size distribution of earthquakes in specified study areas. Methods for estimating the fundamental catalogue parameters like the Gutenberg-Richter (G-R) b-value and the completeness magnitude (Mc) are well established and routinely applied. However, the magnitudes reported in seismicity catalogues contain measurement uncertainties which may significantly distort the estimation of the derived parameters. In this study, we use numerical simulations of synthetic data sets to assess the reliability of different methods for determining b-value and Mc, assuming the G-R law validity. After contaminating the synthetic catalogues with Gaussian noise (with selected standard deviations), the analysis is performed for numerous data sets of different sample size (N). The noise introduced to the data generally leads to a systematic overestimation of magnitudes close to and above Mc. This fact causes an increase of the average number of events above Mc, which in turn leads to an apparent decrease of the b-value. This may result to a significant overestimation of seismicity rate even well above the actual completeness level. The b-value can in general be reliably estimated even for relatively small data sets (N < 1000) when only magnitudes higher than the actual completeness level are used. Nevertheless, a correction of the total number of events belonging in each magnitude class (i.e. 0.1 unit) should be considered, to deal with the magnitude uncertainty effect. Because magnitude uncertainties (here with the form of Gaussian noise) are inevitable in all instrumental catalogues, this finding is fundamental for seismicity rate and seismic hazard assessment analyses. Also important is that for some data analyses significant bias cannot necessarily be avoided by choosing a high Mc value for analysis. In such cases, there may be a risk of severe miscalculation of

Seismic Hazard Implication of the Seismotectonics of southern Africa

NASA Astrophysics Data System (ADS)

Midzi, Vunganai; Mulabisana, Thifelimbilu; Manzunzu, Brassnavy

2014-05-01

The work presented in this report / presentation was prepared as part of the requirements for the SIDA/IGCP Project 601 titled "Seismotectonics and Seismic Hazards in Africa" as well as part of the seismic source characterisation of the GEM-Africa Seismic hazard study. An effort was made to compile information necessary to prepare a seismotectonic map of Africa which can then be used in carrying out a seismic hazard assessment of the continent or locations within the continent. Information on major faults, fault plane solutions, geophysical data as well as stress data has so far been collected and included in a database for the southern Africa region. Reports published by several experts contributed much to the collected information. The seismicity data used are part of the earthquake catalogue being prepared for the GEM-Africa project, which includes historical and instrumental records as collected from various sources. An effort has been made to characterise the identified major faults and through further analysis investigate their possible impact on the seismic hazard of southern Africa.

Seismic risk management of non-engineered buildings

NASA Astrophysics Data System (ADS)

Winar, Setya

Earthquakes have long been feared as one of nature's most terrifying and devastating events. Although seismic codes clearly exist in countries with a high seismic risk to save lives and human suffering, earthquakes still continue to cause tragic events with high death tolls, particularly due to the collapse of widespread non-engineered buildings with non-seismic resistance in developing countries such as Indonesia. The implementation of seismic codes in non-engineered construction is the key to ensuring earthquake safety. In fact, such implementation is not simple, because it comprises all forms of cross disciplinary and cross sectoral linkages at different levels of understanding, commitment, and skill. This fact suggests that a widely agreed framework can help to harmonise the various perspectives. Hence, this research is aimed at developing an integrated framework for guiding and monitoring seismic risk reduction of non-engineered buildings in Indonesia via a risk management method.Primarily, the proposed framework for the study has drawn heavily on wider literature, the three existing frameworks around the world, and on the contribution of various stakeholders who participated in the study. A postal questionnaire survey, selected interviews, and workshop event constituted the primary data collection methods. As a robust framework needed to be achieved, the following two workshop events, which were conducted in Yogyakarta City and Bengkulu City in Indonesia, were carried out for practicality, validity, and moderation or any identifiable improvement requirements. The data collected was analysed with the assistance of SPSS and NVivo software programmes.This research found that the content of the proposed framework comprises 63 pairs of characteristic-indicators complemented by (a) three important factors of effective seismic risk management of non-engineered buildings, (b) three guiding principles for sustainable dissemination to the grass root communities and (c

Maturity of nearby faults influences seismic hazard from hydraulic fracturing.

PubMed

Kozłowska, Maria; Brudzinski, Michael R; Friberg, Paul; Skoumal, Robert J; Baxter, Nicholas D; Currie, Brian S

2018-02-20

Understanding the causes of human-induced earthquakes is paramount to reducing societal risk. We investigated five cases of seismicity associated with hydraulic fracturing (HF) in Ohio since 2013 that, because of their isolation from other injection activities, provide an ideal setting for studying the relations between high-pressure injection and earthquakes. Our analysis revealed two distinct groups: ( i ) deeper earthquakes in the Precambrian basement, with larger magnitudes (M > 2), b-values < 1, and many post-shut-in earthquakes, versus ( ii ) shallower earthquakes in Paleozoic rocks ∼400 m below HF, with smaller magnitudes (M < 1), b-values > 1.5, and few post-shut-in earthquakes. Based on geologic history, laboratory experiments, and fault modeling, we interpret the deep seismicity as slip on more mature faults in older crystalline rocks and the shallow seismicity as slip on immature faults in younger sedimentary rocks. This suggests that HF inducing deeper seismicity may pose higher seismic hazards. Wells inducing deeper seismicity produced more water than wells with shallow seismicity, indicating more extensive hydrologic connections outside the target formation, consistent with pore pressure diffusion influencing seismicity. However, for both groups, the 2 to 3 h between onset of HF and seismicity is too short for typical fluid pressure diffusion rates across distances of ∼1 km and argues for poroelastic stress transfer also having a primary influence on seismicity.

Maturity of nearby faults influences seismic hazard from hydraulic fracturing

NASA Astrophysics Data System (ADS)

Kozłowska, Maria; Brudzinski, Michael R.; Friberg, Paul; Skoumal, Robert J.; Baxter, Nicholas D.; Currie, Brian S.

2018-02-01

Understanding the causes of human-induced earthquakes is paramount to reducing societal risk. We investigated five cases of seismicity associated with hydraulic fracturing (HF) in Ohio since 2013 that, because of their isolation from other injection activities, provide an ideal setting for studying the relations between high-pressure injection and earthquakes. Our analysis revealed two distinct groups: (i) deeper earthquakes in the Precambrian basement, with larger magnitudes (M > 2), b-values < 1, and many post–shut-in earthquakes, versus (ii) shallower earthquakes in Paleozoic rocks ˜400 m below HF, with smaller magnitudes (M < 1), b-values > 1.5, and few post–shut-in earthquakes. Based on geologic history, laboratory experiments, and fault modeling, we interpret the deep seismicity as slip on more mature faults in older crystalline rocks and the shallow seismicity as slip on immature faults in younger sedimentary rocks. This suggests that HF inducing deeper seismicity may pose higher seismic hazards. Wells inducing deeper seismicity produced more water than wells with shallow seismicity, indicating more extensive hydrologic connections outside the target formation, consistent with pore pressure diffusion influencing seismicity. However, for both groups, the 2 to 3 h between onset of HF and seismicity is too short for typical fluid pressure diffusion rates across distances of ˜1 km and argues for poroelastic stress transfer also having a primary influence on seismicity.

EMERALD: Coping with the Explosion of Seismic Data

NASA Astrophysics Data System (ADS)

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

2009-12-01

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

Investigation of Nonlinear Site Response and Seismic Compression from Case History Analysis and Laboratory Testing

NASA Astrophysics Data System (ADS)

Yee, Eric

). Aside from the expected strong influence of RC, increasing fines content is found to generally decrease volume change for fines fractions consisting of silts and clayey silts with moderate to low plasticity. With truly non-plastic fines (rock flour), cyclic volume change increases with FC. Some materials also exhibit an effect of as-compacted saturation in which moderate saturation levels associated with high matric suction cause volume change to decrease. A preliminary empirical model to capture these effects is presented. The balance of the dissertation is related to a case history of strongly nonlinear site response and seismic compression associated with a free-field downhole array installed near the Service Hall at the Kashiwazaki-Kariwa nuclear power plant, which recorded strong ground motions from the Mw 6.6 2007 Niigata-ken Chuetsu-oki earthquake. Site conditions at the array consist of about 70 m of medium-dense sands overlying clayey bedrock, with ground water located at 45 m. Ground shaking at the bedrock level had geometric mean peak accelerations of 0.55 g which is reduced to 0.4 g at the ground surface, indicating nonlinear site response. Ground settlements of approximately 15+/-5 cm occurred at the site. A site investigation was performed to develop relevant soil properties for ground response and seismic compression analysis, including shear wave velocities, shear strength, relative density, and modulus reduction and damping curves. (Abstract shortened by UMI.)

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Properties of seismic absorption induced reflections

NASA Astrophysics Data System (ADS)

Zhao, Haixia; Gao, Jinghuai; Peng, Jigen

2018-05-01

Seismic reflections at an interface are often regarded as the variation of the acoustic impedance (product of seismic velocity and density) in a medium. In fact, they can also be generated due to the difference in absorption of the seismic energy. In this paper, we investigate the properties of such reflections. Based on the diffusive-viscous wave equation and elastic diffusive-viscous wave equation, we investigate the dependency of the reflection coefficients on frequency, and their variations with incident angles. Numerical results at a boundary due to absorption contrasts are compared with those resulted from acoustic impedance variation. It is found that, the reflection coefficients resulted from absorption depend significantly on the frequency especially at lower frequencies, but vary very slowly at small incident angles. At the higher frequencies, the reflection coefficients of diffusive-viscous wave and elastic diffusive-viscous wave are close to those of acoustic and elastic cases, respectively. On the other hand, the reflections caused by acoustic impedance variation are independent of frequency but vary distinctly with incident angles before the critical angle. We also investigate the difference between the seismograms generated in the two different media. The numerical results show that the amplitudes of these reflected waves are attenuated and their phases are shifted. However, the reflections obtained by acoustic impedance contrast, show no significant amplitude attenuation and phase shift.

Effects on Chilean Vertical Reference Frame due to the Maule Earthquake co-seismic and post-seismic effects

NASA Astrophysics Data System (ADS)

Montecino, Henry D.; de Freitas, Silvio R. C.; Báez, Juan C.; Ferreira, Vagner G.

2017-12-01

The Maule Earthquake (Mw = 8.8) of February 27, 2010 is among the strongest earthquakes that occurred in recent years throughout the world. The crustal deformation caused by this earthquake has been widely studied using GNSS, InSAR and gravity observations. However, there is currently no estimation of the possible vertical deformations produced by co-seismic and post-seismic effects in segments of the Chilean Vertical Reference Frame (CHVRF). In this paper, we present an estimation of co-seismic and post-seismic deformations on the CHVRF using an indirect approach based on GNSS and Gravity Recovery and Climate Experiment (GRACE) data as well as by applying a trajectory model. GNSS time series were used from 10 continuous GNSS stations in the period from 2007 to 2015, as well as 28 GNSS temporary stations realized before and after the earthquake, and 34 vertical deformation vectors in the region most affected by the earthquake. We considered a set of 147 monthly solutions of spherical harmonic gravity field that were expanded up to degree, as well as order 96 of the GRACE mission provided by Center for Space Research, University of Texas at Austin (UT-CSR) process center. The magnitude of vertical deformation was estimated in part of the Chilean vertical network due to the co-seismic and post-seismic effects. Once we evaluated the hydrological effect, natural and artificial jumps, and the effect of glacial isostatic adjustment in GNSS and GRACE time series, the maximum values associated to co- and post-seismic deformations on orthometric height were found to be ∼-34 cm and 5 cm, respectively. Overall, the deformation caused by the Maule earthquake in orthometric heights is almost entirely explained by the variation in the ellipsoidal heights (over 85% in co-seismic jump); however, coseismic jump in the geoid reached -3.3 mm, and could influence the maintenance of a modern vertical reference network in a medium to long term. We evaluated the consistency for a

Full Waveform Modelling for Subsurface Characterization with Converted-Wave Seismic Reflection

NASA Astrophysics Data System (ADS)

Triyoso, Wahyu; Oktariena, Madaniya; Sinaga, Edycakra; Syaifuddin, Firman

2017-04-01

While a large number of reservoirs have been explored using P-waves seismic data, P-wave seismic survey ceases to provide adequate result in seismically and geologically challenging areas, like gas cloud, shallow drilling hazards, strong multiples, highly fractured, anisotropy. Most of these reservoir problems can be addressed using P and PS seismic data combination. Multicomponent seismic survey records both P-wave and S-wave unlike conventional survey that only records compressional P-wave. Under certain conditions, conventional energy source can be used to record P and PS data using the fact that compressional wave energy partly converts into shear waves at the reflector. Shear component can be recorded using down going P-wave and upcoming S-wave by placing a horizontal component geophone on the ocean floor. A synthetic model is created based on real data to analyze the effect of gas cloud existence to PP and PS wave reflections which has a similar characteristic to Sub-Volcanic imaging. The challenge within the multicomponent seismic is the different travel time between P-wave and S-wave, therefore the converted-wave seismic data should be processed with different approach. This research will provide a method to determine an optimum converted point known as Common Conversion Point (CCP) that can solve the Asymmetrical Conversion Point of PS data. The value of γ (Vp/Vs) is essential to estimate the right CCP that will be used in converted-wave seismic processing. This research will also continue to the advanced processing method of converted-wave seismic by applying Joint Inversion to PP&PS seismic. Joint Inversion is a simultaneous model-based inversion that estimates the P&S-wave impedance which are consistent with the PP&PS amplitude data. The result reveals a more complex structure mirrored in PS data below the gas cloud area. Through estimated γ section resulted from Joint Inversion, we receive a better imaging improvement below gas cloud area tribute to

ANZA Seismic Network- From Monitoring to Science

NASA Astrophysics Data System (ADS)

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

2007-05-01

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

Alaska Volcano Observatory Seismic Network Data Availability

NASA Astrophysics Data System (ADS)

Dixon, J. P.; Haney, M. M.; McNutt, S. R.; Power, J. A.; Prejean, S. G.; Searcy, C. K.; Stihler, S. D.; West, M. E.

2009-12-01

The Alaska Volcano Observatory (AVO) established in 1988 as a cooperative program of the U.S. Geological Survey, the Geophysical Institute at the University of Alaska Fairbanks, and the Alaska Division of Geological and Geophysical Surveys, monitors active volcanoes in Alaska. Thirty-three volcanoes are currently monitored by a seismograph network consisting of 193 stations, of which 40 are three-component stations. The current state of AVO’s seismic network, and data processing and availability are summarized in the annual AVO seismological bulletin, Catalog of Earthquake Hypocenters at Alaska Volcanoes, published as a USGS Data Series (most recent at http://pubs.usgs.gov/ds/467). Despite a rich seismic data set for 12 VEI 2 or greater eruptions, and over 80,000 located earthquakes in the last 21 years, the volcanic seismicity in the Aleutian Arc remains understudied. Initially, AVO seismic data were only provided via a data supplement as part of the annual bulletin, or upon request. Over the last few years, AVO has made seismic data more available with the objective of increasing volcano seismic research on the Aleutian Arc. The complete AVO earthquake catalog data are now available through the annual AVO bulletin and have been submitted monthly to the on-line Advanced National Seismic System (ANSS) composite catalog since 2008. Segmented waveform data for all catalog earthquakes are available upon request and efforts are underway to make this archive web accessible as well. Continuous data were first archived using a tape backup, but the availability of low cost digital storage media made a waveform backup of continuous data a reality. Currently the continuous AVO waveform data can be found in several forms. Since late 2002, AVO has burned all continuous waveform data to DVDs, as well as storing these data in Antelope databases at the Geophysical Institute. Beginning in 2005, data have been available through a Winston Wave Server housed at the USGS in

ASDF: An Adaptable Seismic Data Format with Full Provenance

NASA Astrophysics Data System (ADS)

Smith, J. A.; Krischer, L.; Tromp, J.; Lefebvre, M. P.

2015-12-01

In order for seismologists to maximize their knowledge of how the Earth works, they must extract the maximum amount of useful information from all recorded seismic data available for their research. This requires assimilating large sets of waveform data, keeping track of vast amounts of metadata, using validated standards for quality control, and automating the workflow in a careful and efficient manner. In addition, there is a growing gap between CPU/GPU speeds and disk access speeds that leads to an I/O bottleneck in seismic workflows. This is made even worse by existing seismic data formats that were not designed for performance and are limited to a few fixed headers for storing metadata.The Adaptable Seismic Data Format (ASDF) is a new data format for seismology that solves the problems with existing seismic data formats and integrates full provenance into the definition. ASDF is a self-describing format that features parallel I/O using the parallel HDF5 library. This makes it a great choice for use on HPC clusters. The format integrates the standards QuakeML for seismic sources and StationXML for receivers. ASDF is suitable for storing earthquake data sets, where all waveforms for a single earthquake are stored in a one file, ambient noise cross-correlations, and adjoint sources. The format comes with a user-friendly Python reader and writer that gives seismologists access to a full set of Python tools for seismology. There is also a faster C/Fortran library for integrating ASDF into performance-focused numerical wave solvers, such as SPECFEM3D_GLOBE. Finally, a GUI tool designed for visually exploring the format exists that provides a flexible interface for both research and educational applications. ASDF is a new seismic data format that offers seismologists high-performance parallel processing, organized and validated contents, and full provenance tracking for automated seismological workflows.

Preface to the focus section on injection-induced seismicity

USGS Publications Warehouse

Eaton, David; Rubinstein, Justin L.

2015-01-01

The ongoing, dramatic increase in seismicity in the central United States that began in 2009 is believed to be the result of injection‐induced seismicity (Ellsworth, 2013). Although the basic mechanism for activation of slip on a fault by subsurface fluid injection is well established (Healy et al., 1968; Raleighet al., 1976; Nicholson and Wesson, 1992; McGarr et al., 2002; Ellsworth, 2013), the occurrence of damaging M≥5 earthquakes and the dramatic increase in seismicity in the central United States has brought heightened attention to this issue. The elevated seismicity is confined to a limited number of areas, and accumulating evidence indicates that the seismicity in these locations is directly linked to nearby industrial operations. This Seismological Research Letters (SRL) focus section presents a selected set of seven technical papers that cover various aspects of this topic, including basic seismological and ground‐motion observations, case studies, numerical simulation of fault activation, and risk mitigation.

Geological investigation for CO2 storage: from seismic and well data to storage design

NASA Astrophysics Data System (ADS)

Chapuis, Flavie; Bauer, Hugues; Grataloup, Sandrine; Leynet, Aurélien; Bourgine, Bernard; Castagnac, Claire; Fillacier, Simon; Lecomte, Antony; Le Gallo, Yann; Bonijoly, Didier

2010-05-01

Geological investigation for CO2 storage: from seismic and well data to storage design Chapuis F.1, Bauer H.1, Grataloup S.1, Leynet A.1, Bourgine B.1, Castagnac C.1, Fillacier, S.2, Lecomte A.2, Le Gallo Y.2, Bonijoly D.1. 1 BRGM, 3 av Claude Guillemin, 45060 Orléans Cedex, France, f.chapuis@brgm.fr, d.bonijoly@brgm.fr 2 Geogreen, 7, rue E. et A. Peugeot, 92563 Rueil-Malmaison Cedex, France, ylg@greogreen.fr The main purpose of this study is to evaluate the techno-economical potential of storing 200 000 tCO2 per year produced by a sugar beat distillery. To reach this goal, an accurate hydro-geological characterisation of a CO2 injection site is of primary importance because it will strongly influence the site selection, the storage design and the risk management. Geological investigation for CO2 storage is usually set in the center or deepest part of sedimentary basins. However, CO2 producers do not always match with the geological settings, and so other geological configurations have to be studied. This is the aim of this project, which is located near the South-West border of the Paris Basin, in the Orléans region. Special geometries such as onlaps and pinch out of formation against the basement are likely to be observed and so have to be taken into account. Two deep saline aquifers are potentially good candidates for CO2 storage. The Triassic continental deposits capped by the Upper Triassic/Lower Jurassic continental shales and the Dogger carbonate deposits capped by the Callovian and Oxfordian shales. First, a data review was undertaken, to provide the palaeogeographical settings and ideas about the facies, thicknesses and depth of the targeted formations. It was followed by a seismic interpretation. Three hundred kilometres of seismic lines were reprocessed and interpreted to characterize the geometry of the studied area. The main structure identified is the Étampes fault that affects all the formations. Apart from the vicinity of the fault where drag

A seismic hazard uncertainty analysis for the New Madrid seismic zone

USGS Publications Warehouse

Cramer, C.H.

2001-01-01

A review of the scientific issues relevant to characterizing earthquake sources in the New Madrid seismic zone has led to the development of a logic tree of possible alternative parameters. A variability analysis, using Monte Carlo sampling of this consensus logic tree, is presented and discussed. The analysis shows that for 2%-exceedence-in-50-year hazard, the best-estimate seismic hazard map is similar to previously published seismic hazard maps for the area. For peak ground acceleration (PGA) and spectral acceleration at 0.2 and 1.0 s (0.2 and 1.0 s Sa), the coefficient of variation (COV) representing the knowledge-based uncertainty in seismic hazard can exceed 0.6 over the New Madrid seismic zone and diminishes to about 0.1 away from areas of seismic activity. Sensitivity analyses show that the largest contributor to PGA, 0.2 and 1.0 s Sa seismic hazard variability is the uncertainty in the location of future 1811-1812 New Madrid sized earthquakes. This is followed by the variability due to the choice of ground motion attenuation relation, the magnitude for the 1811-1812 New Madrid earthquakes, and the recurrence interval for M>6.5 events. Seismic hazard is not very sensitive to the variability in seismogenic width and length. Published by Elsevier Science B.V.

a Comparative Case Study of Reflection Seismic Imaging Method

NASA Astrophysics Data System (ADS)

Alamooti, M.; Aydin, A.

2017-12-01

Seismic imaging is the most common means of gathering information about subsurface structural features. The accuracy of seismic images may be highly variable depending on the complexity of the subsurface and on how seismic data is processed. One of the crucial steps in this process, especially in layered sequences with complicated structure, is the time and/or depth migration of seismic data.The primary purpose of the migration is to increase the spatial resolution of seismic images by repositioning the recorded seismic signal back to its original point of reflection in time/space, which enhances information about complex structure. In this study, our objective is to process a seismic data set (courtesy of the University of South Carolina) to generate an image on which the Magruder fault near Allendale SC can be clearly distinguished and its attitude can be accurately depicted. The data was gathered by common mid-point method with 60 geophones equally spaced along an about 550 m long traverse over a nearly flat ground. The results obtained from the application of different migration algorithms (including finite-difference and Kirchhoff) are compared in time and depth domains to investigate the efficiency of each algorithm in reducing the processing time and improving the accuracy of seismic images in reflecting the correct position of the Magruder fault.

Seismic imaging in hardrock environments: The role of heterogeneity?

NASA Astrophysics Data System (ADS)

Bongajum, Emmanuel; Milkereit, Bernd; Adam, Erick; Meng, Yijian

2012-10-01

We investigate the effect of petrophysical scale parameters and structural dips on wave propagation and imaging in heterogeneous media. Seismic wave propagation effects within the heterogeneous media are studied for different velocity models with scale lengths determined via stochastic analysis of petrophysical logs from the Matagami mine, Quebec, Canada. The elastic modeling study reveals that provided certain conditions of the velocity fluctuations are met, strong local distortions of amplitude and arrival times of propagating waves are observed as the degree of scale length anisotropy in the P-wave velocity increases. The location of these local amplitude anomalies is related to the dips characterizing the fabric of the host rocks. This result is different from the elliptical shape of direct waves often defined by effective anisotropic parameters used for layered media. Although estimates of anisotropic parameters suggest weak anisotropy in the investigated models, these effective anisotropic parameters often used in VTI/TTI do not sufficiently describe the effects of scale length anisotropy in heterogeneous media that show such local amplitude, travel time, and phase distortions in the wavefields. Numerical investigations on the implications for reverse time migration (RTM) routines corroborate that mean P-wave velocity of the host rocks produces reliable imaging results. Based on the RTM results, we postulate the following: weak anisotropy in hardrock environments is a sufficient assumption for processing seismic data; and seismic scattering effects due to velocity heterogeneity with a dip component is not sufficient to cause mislocation errors of target structures as observed in the discrepancy between the location of the strong seismic reflections associated to the Matagami sulfide orebody and its true location. Future work will investigate other factors that may provide plausible explanations for these mislocation problems, with the objective of providing a

Seismic cross-coupling noise in torsion pendulums

NASA Astrophysics Data System (ADS)

Shimoda, Tomofumi; Aritomi, Naoki; Shoda, Ayaka; Michimura, Yuta; Ando, Masaki

2018-05-01

Detection of low-frequency gravitational waves around 0.1 Hz is one of the important targets for future gravitational wave observation. One of the main sources of the expected signals is gravitational waves from binary intermediate-mass black hole coalescences which is proposed as one of the formation scenarios of supermassive black holes. By using a torsion pendulum, which can have a resonance frequency of a few millihertz, such signals can be measured on the ground since its rotational motion can act as a free mass down to 0.01 Hz. However, sensitivity of a realistic torsion pendulum will suffer from torsional displacement noise introduced from translational ground motion in the main frequency band of interest. Such noise is called seismic cross-coupling noise, and there has been little research on it. In this paper, systematic investigation is performed to identify routes of cross-coupling transfer for standard torsion pendulums. Based on the results, this paper also proposes reduction schemes of cross-coupling noise, and they were demonstrated experimentally in agreement with theory. This result establishes a basic way to reduce seismic noise in torsion pendulums for the most significant coupling routes.

A decade of passive seismic monitoring experiments with local networks in four Italian regions

NASA Astrophysics Data System (ADS)

Chiaraluce, L.; Valoroso, L.; Anselmi, M.; Bagh, S.; Chiarabba, C.

2009-10-01

We report on four seismic monitoring experiments that in the past ten years we carried out with dense local networks in seismically active Italian areas where for at least a year, tens of three component seismic stations were set up to record microseismicity. The areas observed are Alpago-Cansiglio, located in the Venetian Alps, Città di Castello in the Northern Apennines, Marsica in the Central Apennines and Val d'Agri located in the Southern Apennines. We produced homogeneous catalogues regarding earthquake locations and local magnitudes to investigate seismicity patterns during an inter-seismic period. The four regions are characterised by different kinematics, strain rates and historical/recent seismicity. We investigate earthquake distribution in space, time and size obtaining reference seismic rates and parameters of the Gutenberg and Richter law. We declustered the catalogues to look for coherent signs in the background seismic activity. Despite a difference in the catalogues magnitudes of completeness due both to the diverse detection threshold of the local networks and different seismic release, we detect and observe two common main behaviours: a) The Alpago-Cansiglio and Marsica regions are characterised by a relatively lower rate of seismic release associated to the episodic occurrence of seismic sequences with the largest event being 3 < ML < 4. In these areas the seismicity is not localised around the main faults. b) The Città di Castello and Val d'Agri regions have a relatively high rate of seismicity release almost continuously with time, and the increase in earthquake production is not clearly related to seismic sequences. In these areas the seismicity nucleates around defined fault systems and is usually lower than ML < 3. We suggest that the presence of over-pressured fluids in the Città di Castello and Val d'Agri uppermost crustal volume may favour and mould the higher rate of microseismic release.

United States National Seismic Hazard Maps

USGS Publications Warehouse

Petersen, M.D.; ,

2008-01-01

The U.S. Geological Survey?s maps of earthquake shaking hazards provide information essential to creating and updating the seismic design provisions of building codes and insurance rates used in the United States. Periodic revisions of these maps incorporate the results of new research. Buildings, bridges, highways, and utilities built to meet modern seismic design provisions are better able to withstand earthquakes, not only saving lives but also enabling critical activities to continue with less disruption. These maps can also help people assess the hazard to their homes or places of work and can also inform insurance rates.

Seismic behavior of a low-rise horizontal cylindrical tank

NASA Astrophysics Data System (ADS)

Fiore, Alessandra; Rago, Carlo; Vanzi, Ivo; Greco, Rita; Briseghella, Bruno

2018-05-01

Cylindrical storage tanks are widely used for various types of liquids, including hazardous contents, thus requiring suitable and careful design for seismic actions. The study herein presented deals with the dynamic analysis of a ground-based horizontal cylindrical tank containing butane and with its safety verification. The analyses are based on a detailed finite element (FE) model; a simplified one-degree-of-freedom idealization is also set up and used for verification of the FE results. Particular attention is paid to sloshing and asynchronous seismic input effects. Sloshing effects are investigated according to the current literature state of the art. An efficient methodology based on an "impulsive-convective" decomposition of the container-fluid motion is adopted for the calculation of the seismic force. The effects of asynchronous ground motion are studied by suitable pseudo-static analyses. Comparison between seismic action effects, obtained with and without consideration of sloshing and asynchronous seismic input, shows a rather important influence of these conditions on the final results.

Seismic Interface Waves in Coastal Waters: A Review

DTIC Science & Technology

1980-11-15

Being at the low- 4 frequency end of classical sonar activity and at the high-frequency end of seismic research, the propagation of infrasonic energy...water areas. Certainly this and other seismic detection methods will never replace the highly-developed sonar techniques but in coastal waters they...for many sonar purposes [5, 85 to 90) shows that very simple bottom models may already be sufficient to make allowance for the influence of the sea

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

the Great Maule earthquake the Collaborative Research Center SFB 574 'Volatiles and Fluids in Subduction Zones' shot several wide-angle profiles and operated a network, also consisting of OBS and land stations for six months in 2008. Both projects provide a great opportunity to study the evolution of a subduction zone within the seismic cycle of a great earthquake. The most profound features are (i) a sharp reduction in intraslab seismic activity after the Maule earthquake and (ii) a sharp increase in seismic activity at the slab interface above 50 km depth, where large parts of the rupture zone were largely aseismic prior to the Maule earthquake. Further, the aftershock seismicity shows a broader depth distribution above 50 km depth.

The Collaborative Seismic Earth Model: Generation 1

NASA Astrophysics Data System (ADS)

Fichtner, Andreas; van Herwaarden, Dirk-Philip; Afanasiev, Michael; SimutÄ--, SaulÄ--; Krischer, Lion; ćubuk-Sabuncu, Yeşim; Taymaz, Tuncay; Colli, Lorenzo; Saygin, Erdinc; Villaseñor, Antonio; Trampert, Jeannot; Cupillard, Paul; Bunge, Hans-Peter; Igel, Heiner

2018-05-01

We present a general concept for evolutionary, collaborative, multiscale inversion of geophysical data, specifically applied to the construction of a first-generation Collaborative Seismic Earth Model. This is intended to address the limited resources of individual researchers and the often limited use of previously accumulated knowledge. Model evolution rests on a Bayesian updating scheme, simplified into a deterministic method that honors today's computational restrictions. The scheme is able to harness distributed human and computing power. It furthermore handles conflicting updates, as well as variable parameterizations of different model refinements or different inversion techniques. The first-generation Collaborative Seismic Earth Model comprises 12 refinements from full seismic waveform inversion, ranging from regional crustal- to continental-scale models. A global full-waveform inversion ensures that regional refinements translate into whole-Earth structure.

Imaging near surface mineral targets with ambient seismic noise

NASA Astrophysics Data System (ADS)

Dales, P.; Audet, P.; Olivier, G.

2017-12-01

To keep up with global metal and mineral demand, new ore-deposits have to be discovered on a regular basis. This task is becoming increasingly difficult, since easily accessible deposits have been exhausted to a large degree. The typical procedure for mineral exploration begins with geophysical surveys followed by a drilling program to investigate potential targets. Since the retrieved drill core samples are one-dimensional observations, the many holes needed to interpolate and interpret potential deposits can lead to very high costs. To reduce the amount of drilling, active seismic imaging is sometimes used as an intermediary, however the active sources (e.g. large vibrating trucks or explosive shots) are expensive and unsuitable for operation in remote or environmentally sensitive areas. In recent years, passive seismic imaging using ambient noise has emerged as a novel, low-cost and environmentally sensitive approach for exploring the sub-surface. This technique dispels with active seismic sources and instead uses ambient seismic noise such as ocean waves, traffic or minor earthquakes. Unfortunately at this point, passive surveys are not capable of reaching the required resolution to image the vast majority of the ore-bodies that are being explored. In this presentation, we will show the results of an experiment where ambient seismic noise recorded on 60 seismic stations was used to image a near-mine target. The target consists of a known ore-body that has been partially exhausted by mining efforts roughly 100 years ago. The experiment examined whether ambient seismic noise interferometry can be used to image the intact and exhausted ore deposit. A drilling campaign was also conducted near the target which offers the opportunity to compare the two methods. If the accuracy and resolution of passive seismic imaging can be improved to that of active surveys (and beyond), this method could become an inexpensive intermediary step in the exploration process and result

Hydrophone Investigations of Earthquakes and Explosion Generated High-Frequency Seismic Phases

DTIC Science & Technology

1989-06-30

stacked along three axes, a temperature sensor , a 2- component tiltmeter , and floating point analog-to-digital electronics. It is clamped inside the... sensors within the ocean- sediment-basement column in order to maximize the signal-to-noise ratio and the signal fidelity of various seismic and acoustic...improved by siting the sensors below the ocean-sediment interface. These changes are especially pronounced on horizontal sensors . Although siting the

Effect of dewatering on seismic performance of multi-anchor wall due to high ground water level

NASA Astrophysics Data System (ADS)

Kobayashi, Makoto; Miura, Kinya; Konami, Takeharu; Hayashi, Taketo; Sato, Hiroki

2017-10-01

Previous research reported that the ground water in the backfill of reinforced soil wall made it deteriorate. According to the damage investigation of Great East Earthquake 2011, the reinforced soil structure due to high ground water level by seismic wave were deformed remarkably. Some of them classified ultimate limit state or restorability limit state. However, more than 90% of reinforced soil structure, which suffered from this earthquake, were classified into no damage condition. Therefore, it is necessary that the seismic behaviors of multi-anchor wall due to seepage flow should be clarified in order to adopt the performance-based design in such reinforced soil structure. In this study, a series of centrifugal shaking table tests were conducted to investigate the seismic behavior of multi-anchor wall due to high ground water level. The reinforced drainage pipes were installed into the backfill in order to verify the dewatering effect and additional reinforcement. Furthermore, to check only the dewatering effect, the model tests was carried out with several ground water table that was modeled the case reinforced drainage pipes installed. The test results show unique behavior of reinforced region that moved integrally. This implies that the reinforced region has been behaved as if it became one mass, and this behavior make this structure increase seismic performance. Thus, the effectiveness of dewatering was observed remarkably because of decreasing the inertial force during earthquake.

Seismic Structural Setting of Western Farallon Basin, Southern Gulf of California, Mexico.

NASA Astrophysics Data System (ADS)

Pinero-Lajas, D.; Gonzalez-Fernandez, A.; Lopez-Martinez, M.; Lonsdale, P.

2007-05-01

Data from a number of high resolution 2D multichannel seismic (MCS) lines were used to investigate the structure and stratigraphy of the western Farallon basin in the southern Gulf of California. A Generator-Injector air gun provided a clean seismic source shooting each 12 s at a velocity of 6 kts. Each signal was recorded during 6- 8 s, at a sampling interval of 1 ms, by a 600 m long digital streamer with 48 channels and a spacing of 12.5 m. The MCS system was installed aboard CICESE's (Centro de Investigacion Cientifica y de Educacion Superior de Ensenada) 28 m research vessel Francisco de Ulloa. MCS data were conventionally processed, to obtain post- stack time-migrated seismic sections. The MCS seismic sections show a very detailed image of the sub-bottom structure up to 2-3 s two-way travel time (aprox. 2 km). We present detailed images of faulting based on the high resolution and quality of these data. Our results show distributed faulting with many active and inactive faults. Our study also constrains the depth to basement near the southern Baja California eastern coast. The acoustic basement appears as a continuous feature in the western part of the study area and can be correlated with some granite outcrops located in the southern Gulf of California islands. To the East, near the center of the Farallon basin, the acoustic basement changes, it is more discontinuous, and the seismic sections show a number of diffracted waves.

Seismic sequences in the Sombrero Seismic Zone

NASA Astrophysics Data System (ADS)

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

Alaska Seismic Hazards Safety Commission

Science.gov Websites

State Employees ASHSC State of Alaska search Alaska Seismic Hazards Safety Commission View of Anchorage and Commissions Alaska Seismic Hazards Safety Commission (ASHSC) main contant Alaska Seismic Hazards Safety Commission logo Alaska Seismic Hazards Safety Commission (ASHSC) - Mission The Alaska Seismic

Present-Day Mars' Seismicity Predicted From 3-D Thermal Evolution Models of Interior Dynamics

NASA Astrophysics Data System (ADS)

Plesa, A.-C.; Knapmeyer, M.; Golombek, M. P.; Breuer, D.; Grott, M.; Kawamura, T.; Lognonné, P.; Tosi, N.; Weber, R. C.

2018-03-01

The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport mission, to be launched in 2018, will perform a comprehensive geophysical investigation of Mars in situ. The Seismic Experiment for Interior Structure package aims to detect global and regional seismic events and in turn offer constraints on core size, crustal thickness, and core, mantle, and crustal composition. In this study, we estimate the present-day amount and distribution of seismicity using 3-D numerical thermal evolution models of Mars, taking into account contributions from convective stresses as well as from stresses associated with cooling and planetary contraction. Defining the seismogenic lithosphere by an isotherm and assuming two end-member cases of 573 K and the 1073 K, we determine the seismogenic lithosphere thickness. Assuming a seismic efficiency between 0.025 and 1, this thickness is used to estimate the total annual seismic moment budget, and our models show values between 5.7 × 1016 and 3.9 × 1019 Nm.

Seismic performance of low-rise wood buildings

Treesearch

Lawrence A. Soltis; Robert H. Falk

1992-01-01

This article updates a previous literature review paper on the performance of woodframe buildings during earthquakes and summarizes recent research related to understanding seismic behavior of low-rise wood buildings.

Seismic Prediction While Drilling (SPWD): Seismic exploration ahead of the drill bit using phased array sources

NASA Astrophysics Data System (ADS)

Jaksch, Katrin; Giese, Rüdiger; Kopf, Matthias

2010-05-01

maximize the energy of the seismic source in order to reach a sufficient exploration range. The next step for focusing is to use the method of phased array. Dependent of the seismic wave velocities of the surrounding rock, the distance of the actuators to each other and the used frequencies the signal phases for each actuator can be determined. Since one year several measurements with the prototype have been realized under defined conditions at a test site in a mine. The test site consists of a rock block surrounded from three galleries with a dimension of about 100 by 200 meters. For testing the prototype two horizontal boreholes were drilled. They are directed to one of the gallery to get a strong reflector. The quality of the data of the borehole seismics in amplitude and frequency spectra show overall a good signal-to-noise ratio and correlate strongly with the fracture density along the borehole and are associated with a lower signal-to-noise ratio. Additionally, the geophones of the prototype show reflections from ahead and rearward in the seismic data. In particular, the reflections from the gallery ahead are used for the calibration of focusing. The direct seismic wave field indicates distinct compression and shear waves. The analysis of several seismic measurements with a focus on the direct seismic waves shows that the phased array technology explicit can influence the directional characteristics of the radiated seimic waves. The amplitudes of the seismic waves can be enhanced up to three times more in the desired direction and simultaneously be attenuated in the reverse direction. A major step for the directional investigation in boreholes has accomplished. But the focusing of the seismic waves has to be improved to maximize the energy in the desired direction in more measurements by calibrating the initiating seismic signals of the sources. A next step this year is the development of a wireline prototype for application in vertical boreholes with depths not

Baby-Plumes beneath Central Europe - Indications from seismic studies

NASA Astrophysics Data System (ADS)

Achauer, U.; Granet, M.

2011-12-01

The most important result of the seismic investigations in the French Massif Central at the beginning of the 1990' (French-German co-operative project Limagne 91/92) was the proof of an ascending material stream from larger depth (250km), which due to its geochemical, petrological and temperature characteristics and its appearance was classified as a plume and which confirmed an already 20 years earlier expressed hypothesis. The really new of the results were that for the first time the exact size and shape of this plume at upper mantle depths was determined, as well as the fact that no plume head ("mushroom") could be found. This led to the expression of "baby plume" for this kind of material up-streaming in order to differentiate this feature to the classical idea of a plume (such as the model by Shilling). The results from the Massif Central triggered similar seismic experiments in other regions of Central Europe with variscan basement and recent volcanism, such as the Eifel plume project and BOHEMA and led to the proof of another such structure beneath the Eifel volcanic region. In contrast to that does the Bohemian massif anomaly more look like a classic asthenospheric upwarp. Recent investigations, in particularily based on additional data from a project across the southern Massif Central, let assume that the origin of these plume like structures lies in the mantle transition zone and that they might be connected to a fossil slab. In this lecture an overview will be given of the current state of affairs concerning the seismic research on baby plumes, as well as possible causes for their presence will be discussed.

An investigation of the seismic behavior of a deck-type reinforced concrete arch bridge

NASA Astrophysics Data System (ADS)

Farahani, Emadoddin Majdabadi; Maalek, Shahrokh

2017-07-01

This paper attempts to explore potential benefits of form in a deck-type reinforced concrete (RC) arch bridge in connection with its overall seismic behavior and performance. Through a detailed three-dimensional finite element modeling and analysis of an actual existing deck-type RC arch bridge, some useful quantitative information have been derived that may serve for a better understanding of the seismic behavior of such arch bridges. A series of the nonlinear dynamic analyses has been carried out under the action of seven different time histories of ground motion scaled to the AASHTO 2012 response spectrum. The concept of demand to capacity ratios has been employed to provide an initial estimation of the seismic performance of the bridge members. As a consequence of the structural form, a particular type of irregularity is introduced due to variable heights of columns transferring the deck loads to the main arch. Hence, a particular attention has been paid to the internal force/moment distributions within the short, medium, and long columns as well as along the main arch. A study of the effects of the vertical component of ground motion has demonstrated the need for the inclusion of these effects in the analysis of such bridges.

Investigation of the nonlinear seismic behavior of knee braced frames using the incremental dynamic analysis method

NASA Astrophysics Data System (ADS)

Sheidaii, Mohammad Reza; TahamouliRoudsari, Mehrzad; Gordini, Mehrdad

2016-06-01

In knee braced frames, the braces are attached to the knee element rather than the intersection of beams and columns. This bracing system is widely used and preferred over the other commonly used systems for reasons such as having lateral stiffness while having adequate ductility, damage concentration on the second degree convenience of repairing and replacing of these elements after Earthquake. The lateral stiffness of this system is supplied by the bracing member and the ductility of the frame attached to the knee length is supplied through the bending or shear yield of the knee member. In this paper, the nonlinear seismic behavior of knee braced frame systems has been investigated using incremental dynamic analysis (IDA) and the effects of the number of stories in a building, length and the moment of inertia of the knee member on the seismic behavior, elastic stiffness, ductility and the probability of failure of these systems has been determined. In the incremental dynamic analysis, after plotting the IDA diagrams of the accelerograms, the collapse diagrams in the limit states are determined. These diagrams yield that for a constant knee length with reduced moment of inertia, the probability of collapse in limit states heightens and also for a constant knee moment of inertia with increasing length, the probability of collapse in limit states increases.

Questa Baseline and Pre-Mining Ground-Water Quality Investigation. 1. Depth to Bedrock Determinations Using Shallow Seismic Data Acquired in the Straight Creek Drainage Near Red River, New Mexico

USGS Publications Warehouse

Powers, Michael H.; Burton, Bethany L.

2004-01-01

In late May and early June of 2002, the U.S. Geological Survey (USGS) acquired four P-wave seismic profiles across the Straight Creek drainage near Red River, New Mexico. The data were acquired to support a larger effort to investigate baseline and pre-mining ground-water quality in the Red River basin (Nordstrom and others, 2002). For ground-water flow modeling, knowledge of the thickness of the valley fill material above the bedrock is required. When curved-ray refraction tomography was used with the seismic first arrival times, the resulting images of interval velocity versus depth clearly show a sharp velocity contrast where the bedrock interface is expected. The images show that the interpreted buried bedrock surface is neither smooth nor sharp, but it is clearly defined across the valley along the seismic line profiles. The bedrock models defined by the seismic refraction images are consistent with the well data.

Overview of Seismic Noise and it’s Relevance to Personnel Detection

DTIC Science & Technology

2008-04-01

production sites. Young et al. (1996) measured seismic noise with seismometers at the surface and within boreholes at three sites, and generated...ER D C/ CR R EL T R -0 8 -5 Overview of Seismic Noise and its Relevance to Personnel Detection Lindamae Peck April 2008 C ol d R...April 2008 Overview of Seismic Noise and its Relevance to Personnel Detection Lindamae Peck Cold Regions Research and Engineering Laboratory

A GIS-based time-dependent seismic source modeling of Northern Iran

NASA Astrophysics Data System (ADS)

Hashemi, Mahdi; Alesheikh, Ali Asghar; Zolfaghari, Mohammad Reza

2017-01-01

The first step in any seismic hazard study is the definition of seismogenic sources and the estimation of magnitude-frequency relationships for each source. There is as yet no standard methodology for source modeling and many researchers have worked on this topic. This study is an effort to define linear and area seismic sources for Northern Iran. The linear or fault sources are developed based on tectonic features and characteristic earthquakes while the area sources are developed based on spatial distribution of small to moderate earthquakes. Time-dependent recurrence relationships are developed for fault sources using renewal approach while time-independent frequency-magnitude relationships are proposed for area sources based on Poisson process. GIS functionalities are used in this study to introduce and incorporate spatial-temporal and geostatistical indices in delineating area seismic sources. The proposed methodology is used to model seismic sources for an area of about 500 by 400 square kilometers around Tehran. Previous researches and reports are studied to compile an earthquake/fault catalog that is as complete as possible. All events are transformed to uniform magnitude scale; duplicate events and dependent shocks are removed. Completeness and time distribution of the compiled catalog is taken into account. The proposed area and linear seismic sources in conjunction with defined recurrence relationships can be used to develop time-dependent probabilistic seismic hazard analysis of Northern Iran.

Triple seismic source, double research ship, single ambitious goal: integrated imaging of young oceanic crust in the Panama Basin

NASA Astrophysics Data System (ADS)

Wilson, Dean; Peirce, Christine; Hobbs, Richard; Gregory, Emma

2016-04-01

Understanding geothermal heat and mass fluxes through the seafloor is fundamental to the study of the Earth's energy budget. Using geophysical, geological and physical oceanography data we are exploring the interaction between the young oceanic crust and the ocean in the Panama Basin. We acquired a unique geophysical dataset that will allow us to build a comprehensive model of young oceanic crust from the Costa Rica Ridge axis to ODP borehole 504B. Data were collected over two 35 x 35 km2 3D grid areas, one each at the ridge axis and the borehole, and along three 330 km long 2D profiles orientated in the spreading direction, connecting the two grids. In addition to the 4.5 km long multichannel streamer and 75 ocean-bottom seismographs (OBS), we also deployed 12 magnetotelluric (MT) stations and collected underway swath bathymetry, gravity and magnetic data. For the long 2D profiles we used two research vessels operating synchronously. The RRS James Cook towed a high frequency GI-gun array (120 Hz) to image the sediments, and a medium frequency Bolt-gun array (50 Hz) for shallow-to-mid-crustal imaging. The R/V Sonne followed the Cook, 9 km astern and towed a third seismic source; a low frequency, large volume G-gun array (30 Hz) for whole crustal and upper mantle imaging at large offsets. Two bespoke vertical hydrophone arrays recorded real far field signatures that have enabled us to develop inverse source filters and match filters. Here we present the seismic reflection image, forward and inverse velocity-depth models and a density model along the primary 330 km north-south profile, from ridge axis to 6 Ma crust. By incorporating wide-angle streamer data from our two-ship, synthetic aperture acquisition together with traditional wide-angle OBS data we are able to constrain the structure of the upper oceanic crust. The results show a long-wavelength trend of increasing seismic velocity and density with age, and a correlation between velocity structure and basement

Extracting physical parameters from marine seismic data: New methods in seismic oceanography and velocity inversion

NASA Astrophysics Data System (ADS)

Fortin, Will F. J.

The utility and meaning of a geophysical dataset is dependent on good interpretation informed by high-quality data, processing, and attribute examination via technical methodologies. Active source marine seismic reflection data contains a great deal of information in the location, phase, and amplitude of both pre- and post-stack seismic reflections. Using pre- and post-stack data, this work has extracted useful information from marine reflection seismic data in novel ways in both the oceanic water column and the sub-seafloor geology. In chapter 1 we develop a new method for estimating oceanic turbulence from a seismic image. This method is tested on synthetic seismic data to show the method's ability to accurately recover both distribution and levels of turbulent diffusivity. Then we apply the method to real data offshore Costa Rica where we observe lee waves. Our results find elevated diffusivities near the seafloor as well as above the lee waves five times greater than surrounding waters and 50 times greater than open ocean diffusivities. Chapter 2 investigates subsurface geology in the Cascadia Subduction Zone and outlines a workflow for using pre-stack waveform inversion to produce highly detailed velocity models and seismic images. Using a newly developed inversion code, we achieve better imaging results as compared to the product of a standard, user-intensive method for building a velocity model. Our results image the subduction interface ~30 km farther landward than previous work and better images faults and sedimentary structures above the oceanic plate as well as in the accretionary prism. The resultant velocity model is highly detailed, inverted every 6.25 m with ~20 m vertical resolution, and will be used to examine the role of fluids in the subduction system. These results help us to better understand the natural hazards risks associated with the Cascadia Subduction Zone. Chapter 3 returns to seismic oceanography and examines the dynamics of nonlinear

INSPIRE Project (IoNospheric Sounding for Pre-seismic anomalies Identification REsearch): Main Results and Future Prospects

NASA Astrophysics Data System (ADS)

Pulinets, S. A.; Andrzej, K.; Hernandez-Pajares, M.; Cherniak, I.; Zakharenkova, I.; Rothkaehl, H.; Davidenko, D.

2017-12-01

The INSPIRE project is dedicated to the study of physical processes and their effects in ionosphere which could be determined as earthquake precursors together with detailed description of the methodology of ionospheric pre-seismic anomalies definition. It was initiated by ESA and carried out by international consortium. The physical mechanisms of the ionospheric pre-seismic anomalies generation from ground to the ionosphere altitudes were formulated within framework of the Lithosphere-Atmosphere-Ionosphere-Magnetosphere Coupling (LAIMC) model (Pulinets et al., 2015). The general algorithm for the identification of the ionospheric precursors was formalized which also takes into account the external Space Weather factors able to generate the false alarms. Importance of the special stable pattern called the "precursor mask" was highlighted which is based on self-similarity of pre-seismic ionospheric variations. The role of expert decision in pre-seismic anomalies interpretation for generation of seismic warning is important as well. The algorithm performance of the LAIMC seismo-ionospheric effect detection module has been demonstrated using the L'Aquila 2009 earthquake as a case study. The results of INSPIRE project have demonstrated that the ionospheric anomalies registered before the strong earthquakes could be used as reliable precursors. The detailed classification of the pre-seismic anomalies was presented in different regions of the ionosphere and signatures of the pre-seismic anomalies as detected by ground and satellite based instruments were described what clarified methodology of the precursor's identification from ionospheric multi-instrumental measurements. Configuration for the dedicated multi-observation experiment and satellite payload was proposed for the future implementation of the INSPIRE project results. In this regard the multi-instrument set can be divided by two groups: space equipment and ground-based support, which could be used for real

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

USGS Publications Warehouse

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

Patterns of significant seismic quiescence in the Pacific Mexican coast

NASA Astrophysics Data System (ADS)

Muñoz-Diosdado, Alejandro; Rudolf-Navarro, Adolfo; Barrera-Ferrer, Amilcar; Angulo-Brown, Fernando

2014-05-01

Mexico is one of the countries with higher seismicity. During the 20th century, 8% of all the earthquakes in the world of magnitude greater than or equal to 7.0 have taken place in Mexico. On average, an earthquake of magnitude greater than or equal to 7.0 occurred in Mexico every two and a half years. Great earthquakes in Mexico have their epicenters in the Pacific Coast in which some seismic gaps have been identified; for example, there is a mature gap in the Guerrero State Coast, which potentially can produce an earthquake of magnitude 8.2. With the purpose of making some prognosis, some researchers study the statistical behavior of certain physical parameters that could be related with the process of accumulation of stress in the Earth crust. Other researchers study seismic catalogs trying to find seismicity patterns that are manifested before the occurrence of great earthquakes. Many authors have proposed that the study of seismicity rates is an appropriate technique for evaluating how close a seismic gap may be to rupture. We designed an algorithm for identification of patterns of significant seismic quiescence by using the definition of seismic quiescence proposed by Schreider (1990). This algorithm shows the area of quiescence where an earthquake of great magnitude will probably occur. We apply our algorithm to the earthquake catalogue of the Mexican Pacific coast located between 14 and 21 degrees of North latitude and 94 and 106 degrees West longitude; with depths less or equal to 60 km and magnitude greater or equal to 4.2, which occurred from September, 1965 until December, 2014. We have found significant patterns of seismic quietude before the earthquakes of Oaxaca (November 1978, Mw = 7.8), Petatlán (March 1979, Mw = 7.6), Michoacán (September 1985, Mw = 8.0, and Mw = 7.6) and Colima (October 1995, Mw = 8.0). Fortunately, in this century have not occurred earthquakes of great magnitude in Mexico, however, we have identified well-defined seismic

Background noise model development for seismic stations of KMA

NASA Astrophysics Data System (ADS)

Jeon, Youngsoo

2010-05-01

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

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

NASA Astrophysics Data System (ADS)

Zieger, Toni; Ritter, Joachim R. R.

2018-01-01

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

Lattice Boltzmann Simulation of Seismic Mobilization of Residual Oil in Sandstone

NASA Astrophysics Data System (ADS)

Guo, R.; Jiang, F.; Deng, W.

2017-12-01

Seismic stimulation is a promising technology for enhanced oil recovery. However, current mechanism studies are mainly in the single constricted tubes or idealized porous media, and no study has been conducted in real reservoir porous media. We have developed a numerical simulation which uses the lattice Boltzmann method to directly calculate the characteristics of residual oil clusters to quantify seismic mobilization of residual oil in real Berea sandstone in a scale of 400μm x 400μm x 400μm. The residual oil clusters will be firstly obtained by applying the water flooding scheme to the oil-saturated sandstone. Then, we will apply the seismic stimulation to the sandstone by converting the seismic effect to oscillatory inertial force and add to the pore fluids. This oscillatory inertial force causes the mobilization of residual oil by overcoming the capillary force. The response of water and oil to the seismic stimulation will be observed in our simulations. Two seismic oil mobilization mechanisms will be investigated: (1) the passive response of residual oil clusters to the seismic stimulation, and (2) the resonance of oil clusters subject to low frequency seismic stimulation. We will then discuss which mechanism should be the dominant mechanism for the seismic stimulation oil recovery for practical applications.

Challenges in making a seismic hazard map for Alaska and the Aleutians

USGS Publications Warehouse

Wesson, R.L.; Boyd, O.S.; Mueller, C.S.; Frankel, A.D.; Freymueller, J.T.

2008-01-01

We present a summary of the data and analyses leading to the revision of the time-independent probabilistic seismic hazard maps of Alaska and the Aleutians. These maps represent a revision of existing maps based on newly obtained data, and reflect best current judgments about methodology and approach. They have been prepared following the procedures and assumptions made in the preparation of the 2002 National Seismic Hazard Maps for the lower 48 States, and will be proposed for adoption in future revisions to the International Building Code. We present example maps for peak ground acceleration, 0.2 s spectral amplitude (SA), and 1.0 s SA at a probability level of 2% in 50 years (annual probability of 0.000404). In this summary, we emphasize issues encountered in preparation of the maps that motivate or require future investigation and research.

Seismicity and Seismotectonic Properties of The Sultandağı Fault Zone (Afyonkarahisar-Konya): Western Anatolia,Turkey

NASA Astrophysics Data System (ADS)

Kalafat, D.; Gunes, Y.; Kekovali, K.; Kara, M.; Gorgun, E.

2017-12-01

n this study we investigated seismicity and source characteristics of the Sultandağı Fault Zone (SFZ). As known Western Anatolia is one of the most important seismically active region in Turkey. The relative movement of the African-Arabian plates, it causes the Anatolian Plate to movement to the west-Southwest direction 2.5 cm per year and this result provides N-S direction with extensional regime in the recent tectonic. In this study, especially with the assessment of seismic activity occurring in Afyon and around between 200-2002 years, we have been evaluated to date with seismic activity as well as fault mechanism solution. We analyzed recent seismicity and distribution of earthquakes in this region. In the last century, 3 important earthquakes occurred in the Sultandağı Fault zone (Afyon-Akşehir Graben), this result shown it was seismic active and broken fault segments caused stress balance in the region and it caused to occur with short intervals of earthquakes in 2000 and 2002, triggering each other. The scope of this tudy, we installed new BB stations in the region and we have been done of the fault plane solutions for important earthquakes. The focal mechanisms clearly exhibit the activation of a NE-SW trending normal faulting system along the SFZ region. The results of stress analysis showed that the effective current tectonic evolution of normal faulting in this region. This study is supported by Bogazici University Research Projects Commission under SRP/BAP project No. 12280. Key Words: Sultandağı fault zone, normal faulting, seismicity, fault mechanism

Towards Exascale Seismic Imaging and Inversion

NASA Astrophysics Data System (ADS)

Tromp, J.; Bozdag, E.; Lefebvre, M. P.; Smith, J. A.; Lei, W.; Ruan, Y.

2015-12-01

Post-petascale supercomputers are now available to solve complex scientific problems that were thought unreachable a few decades ago. They also bring a cohort of concerns tied to obtaining optimum performance. Several issues are currently being investigated by the HPC community. These include energy consumption, fault resilience, scalability of the current parallel paradigms, workflow management, I/O performance and feature extraction with large datasets. In this presentation, we focus on the last three issues. In the context of seismic imaging and inversion, in particular for simulations based on adjoint methods, workflows are well defined.They consist of a few collective steps (e.g., mesh generation or model updates) and of a large number of independent steps (e.g., forward and adjoint simulations of each seismic event, pre- and postprocessing of seismic traces). The greater goal is to reduce the time to solution, that is, obtaining a more precise representation of the subsurface as fast as possible. This brings us to consider both the workflow in its entirety and the parts comprising it. The usual approach is to speedup the purely computational parts based on code optimization in order to reach higher FLOPS and better memory management. This still remains an important concern, but larger scale experiments show that the imaging workflow suffers from severe I/O bottlenecks. Such limitations occur both for purely computational data and seismic time series. The latter are dealt with by the introduction of a new Adaptable Seismic Data Format (ASDF). Parallel I/O libraries, namely HDF5 and ADIOS, are used to drastically reduce the cost of disk access. Parallel visualization tools, such as VisIt, are able to take advantage of ADIOS metadata to extract features and display massive datasets. Because large parts of the workflow are embarrassingly parallel, we are investigating the possibility of automating the imaging process with the integration of scientific workflow

Seismic-reflection profiles of the New Madrid seismic zone-data along the Mississippi River near Caruthersville, Missouri

USGS Publications Warehouse

Crone, A.J.; Harding, S.T.; Russ, D.P.; Shedlock, K.M.

1986-01-01

Three major seismic-reflection programs have been conducted by the USGS in the New Madrid seismic zone. The first program consisted of 32 km of conventional Vibroseis profiling designed to investigate the subsurface structure associated with scarps and lineaments in northwestern Tennessee (Zoback, 1979). A second, more extensive Vibroseis program collected about 250 km of data from all parts of the New Madrid seismic zone in Missouri, Arkansas, and Tennessee (Hamilton and Zoback, 1979, 1982; Zoback and others, 1980). The profiles presented here are part of the third program that collected about 240 km of high-resolution seismic-reflection data from a boat along the Mississippi River between Osceola, Ark., and Wickliffe, Ky. (fig. 1). The data for profiles A, B, C, and D were collected between river miles 839-1/2 and 850-1/2 from near the Interstate-155 bridge to upstream of Caruthersville, Mo. (fig. 2). Profiles on this part of the river are important for three reasons: (1) they connect many of the land-based profiles on either side of the river, (2) they are near the northeast termination of a linear, 120km-long, northeast-southwest zone of seismicity that extends from northeast Arkansas to Caruthersville, Mo. (Stauder, 1982; fig. 1), and (3) they cross the southwesterly projection of the Cottonwood Grove fault (fig. 1), a fault having a substantial amount of vertical Cenozoic offset (Zoback and others, 1980).

An open source, web based, simple solution for seismic data dissemination and collaborative research

NASA Astrophysics Data System (ADS)

Diviacco, Paolo

2005-06-01

Collaborative research and data dissemination in the field of geophysical exploration need network tools that can access large amounts of data from anywhere using any PC or workstation. Simple solutions based on a combination of Open Source software can be developed to address such requests, exploiting the possibilities offered by the web technologies, and at the same time avoiding the costs and inflexibility of commercial systems. A viable solution consists of MySQL for data storage and retrieval, CWP/SU and GMT for data visualisation and a scripting layer driven by PHP that allows users to access the system via an Apache web server. In the light of the experience building the on-line archive of seismic data of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), we describe the solutions and the methods adopted, with a view to stimulate both the attitude of network collaborative research of other institutions similar to ours, and the development of different applications.

Evaluation of soil-foundation-structure interaction effects on seismic response demands of multi-story MRF buildings on raft foundations

NASA Astrophysics Data System (ADS)

Abdel Raheem, Shehata E.; Ahmed, Mohamed M.; Alazrak, Tarek M. A.

2015-03-01

Soil conditions have a great deal to do with damage to structures during earthquakes. Hence the investigation on the energy transfer mechanism from soils to buildings during earthquakes is critical for the seismic design of multi-story buildings and for upgrading existing structures. Thus, the need for research into soil-structure interaction (SSI) problems is greater than ever. Moreover, recent studies show that the effects of SSI may be detrimental to the seismic response of structure and neglecting SSI in analysis may lead to un-conservative design. Despite this, the conventional design procedure usually involves assumption of fixity at the base of foundation neglecting the flexibility of the foundation, the compressibility of the underneath soil and, consequently, the effect of foundation settlement on further redistribution of bending moment and shear force demands. Hence the SSI analysis of multi-story buildings is the main focus of this research; the effects of SSI are analyzed for typical multi-story building resting on raft foundation. Three methods of analysis are used for seismic demands evaluation of the target moment-resistant frame buildings: equivalent static load; response spectrum methods and nonlinear time history analysis with suit of nine time history records. Three-dimensional FE model is constructed to investigate the effects of different soil conditions and number of stories on the vibration characteristics and seismic response demands of building structures. Numerical results obtained using SSI model with different soil conditions are compared to those corresponding to fixed-base support modeling assumption. The peak responses of story shear, story moment, story displacement, story drift, moments at beam ends, as well as force of inner columns are analyzed. The results of different analysis approaches are used to evaluate the advantages, limitations, and ease of application of each approach for seismic analysis.

Seismic Techniques for Subsurface Voids Detection

NASA Astrophysics Data System (ADS)

Gritto, Roland; Korneev, Valeri; Elobaid Elnaiem, Ali; Mohamed, Fathelrahman; Sadooni, Fadhil

2016-04-01

A major hazards in Qatar is the presence of karst, which is ubiquitous throughout the country including depressions, sinkholes, and caves. Causes for the development of karst include faulting and fracturing where fluids find pathways through limestone and dissolve the host rock to form caverns. Of particular concern in rapidly growing metropolitan areas that expand in heretofore unexplored regions are the collapse of such caverns. Because Qatar has seen a recent boom in construction, including the planning and development of complete new sub-sections of metropolitan areas, the development areas need to be investigated for the presence of karst to determine their suitability for the planned project. In this paper, we present the results of a study to demonstrate a variety of seismic techniques to detect the presence of a karst analog in form of a vertical water-collection shaft located on the campus of Qatar University, Doha, Qatar. Seismic waves are well suited for karst detection and characterization. Voids represent high-contrast seismic objects that exhibit strong responses due to incident seismic waves. However, the complex geometry of karst, including shape and size, makes their imaging nontrivial. While karst detection can be reduced to the simple problem of detecting an anomaly, karst characterization can be complicated by the 3D nature of the problem of unknown scale, where irregular surfaces can generate diffracted waves of different kind. In our presentation we employ a variety of seismic techniques to demonstrate the detection and characterization of a vertical water collection shaft analyzing the phase, amplitude and spectral information of seismic waves that have been scattered by the object. We used the reduction in seismic wave amplitudes and the delay in phase arrival times in the geometrical shadow of the vertical shaft to independently detect and locate the object in space. Additionally, we use narrow band-pass filtered data combining two

Young Investigator Research Program (YIP)

NASA Astrophysics Data System (ADS)

Robinson, Ellen

The Air Force YIP supports scientists and engineers who have received Ph.D. or equivalent degrees in the last five years and show exceptional ability and promise for conducting basic research. The objective of this program is to foster creative basic research in science and engineering; enhance early career development of outstanding young investigators; and increase opportunities for the young investigator to recognize the Air Force mission and related challenges in science and engineering. Individual awards will be made to U.S. institutions of higher education, industrial laboratories or non-profit research organizations where the principal investigator is a U.S. citizen, national or permanent resident; employed on a full-time basis and hold a regular position. Researchers working at the Federally Funded Research and Development Centers and DoD Laboratories will not be considered for the YIP competition. Each award will be funded at the 120K level for three years. Exceptional proposals will be considered individually for higher funding levels and longer duration. http://www.wpafb.af.mil/Welcome/Fact-Sheets/Display/Article/842100#anchor2 I will brief Air Force Office Of Scientific Research Young Investigator Research Program.

Angola seismicity

NASA Astrophysics Data System (ADS)

Neto, Francisco António Pereira; França, George Sand; Condori, Cristobal; Sant'Anna Marotta, Giuliano; Chimpliganond, Cristiano Naibert

2018-05-01

This work describes the development of the Angolan earthquake catalog and seismicity distribution in the Southwestern African Plate, in Angola. This region is one of the least seismically active, even for stable continental regions (SCRs) in the world. The maximum known earthquake had a magnitude of 6.0 Ms, while events with magnitudes of 4.5 have return period of about 10 years. Events with magnitude 5 and above occur with return period of about 20 years. Five seismic zones can be confirmed in Angola, within and along craton edges and in the sedimentary basins including offshore. Overall, the exposed cratonic regions tend to have more earthquakes compared to other regions such as sedimentary basins. Earthquakes tend to occur in Archaic rocks, especially inside preexisting weakness zones and in tectonic-magmatic reactivation zones of Mesozoic and Meso-Cenozoic, associated with the installation of a wide variety of intrusive rocks, strongly marked by intense tectonism. This fact can be explained by the models of preexisting weakness zones and stress concentration near intersecting structures. The Angolan passive margin is also a new region where seismic activity occurs. Although clear differences are found between different areas along the passive margin, in the middle near Porto Amboim city, seismic activity is more frequent compared with northwestern and southwestern regions.

Rescaled Range analysis of Induced Seismicity: rapid classification of clusters in seismic crisis

NASA Astrophysics Data System (ADS)

Bejar-Pizarro, M.; Perez Lopez, R.; Benito-Parejo, M.; Guardiola-Albert, C.; Herraiz, M.

2017-12-01

Different underground fluid operations, mainly gas storing, fracking and water pumping, can trigger Induced Seismicity (IS). This seismicity is normally featured by small-sized earthquakes (M<2.5), although particular cases reach magnitude as great as 5. It has been up for debate whether earthquakes greater than 5 can be triggered by IS or this level of magnitude only corresponds to tectonic earthquakes caused by stress change. Whatever the case, the characterization of IS for seismic clusters and seismic series recorded close but not into the gas storage, is still under discussion. Time-series of earthquakes obey non-linear patterns where the Hurst exponent describes the persistency or anti-persistency of the sequence. Natural seismic sequences have an H-exponent close to 0.7, which combined with the b-value time evolution during the time clusters, give us valuable information about the stationarity of the phenomena. Tectonic earthquakes consist in a main shock with a decay of time-occurrence of seismic shocks obeying the Omori's empirical law. On the contrary, IS does not exhibit a main shock and the time occurrence depends on the injection operations instead of on the tectonic energy released. In this context, the H-exponent can give information about the origin of the sequence. In 2013, a seismic crisis was declared from the Castor underground gas storing located off-shore in the Mediterranean Sea, close to the Northeastern Spanish cost. The greatest induced earthquake was 3.7. However, a 4.2 earthquake, probably of tectonic origin, occurred few days after the operations stopped. In this work, we have compared the H-exponent and the b-value time evolution according to the timeline of gas injection. Moreover, we have divided the seismic sequence into two groups: (1) Induced Seismicity and (2) Triggered Seismicity. The rescaled range analysis allows the differentiation between natural and induced seismicity and gives information about the persistency and long

New comprehensive standard seismic noise models and 3D seismic noise variation for Morocco territory, North Africa, obtained using seismic broadband stations

NASA Astrophysics Data System (ADS)

El Fellah, Younes; El-Aal, Abd El-Aziz Khairy Abd; Harnafi, Mimoun; Villaseñor, Antonio

2017-05-01

In the current work, we constructed new comprehensive standard seismic noise models and 3D temporal-spatial seismic noise level cubes for Morocco in north-west Africa to be used for seismological and engineering purposes. Indeed, the original global standard seismic noise models published by Peterson (1993) and their following updates by Astiz and Creager (1995), Ekström (2001) and Berger et al. (2003) had no contributing seismic stations deployed in North Africa. Consequently, this preliminary study was conducted to shed light on seismic noise levels specific to north-west Africa. For this purpose, 23 broadband seismic stations recently installed in different structural domains throughout Morocco are used to study the nature and characteristics of seismic noise and to create seismic noise models for Morocco. Continuous data recorded during 2009, 2010 and 2011 were processed and analysed to construct these new noise models and 3D noise levels from all stations. We compared the Peterson new high-noise model (NHNM) and low-noise model (NLNM) with the Moroccan high-noise model (MHNM) and low-noise model (MLNM). These new noise models are comparable to the United States Geological Survey (USGS) models in the short period band; however, in the period range 1.2 s to 1000 s for MLNM and 10 s to 1000 s for MHNM display significant variations. This variation is attributed to differences in the nature of seismic noise sources that dominate Morocco in these period bands. The results of this study have a new perception about permanent seismic noise models for this spectacular region and can be considered a significant contribution because it supplements the Peterson models and can also be used to site future permanent seismic stations in Morocco.

Seismic Characterization and Continuity Analysis of Gas Hydrate Horizons Near the Mallik Research Wells, Mackenzie Delta, Canada

NASA Astrophysics Data System (ADS)

Bellefleur, G.; Riedel, M.; Brent, T.

2005-12-01

Gas hydrate deposits in arctic environment generally lack the BSR signature diagnostic of their presence in marine seismic data. The absence of the BSR signature complicates the estimation of the resources within or below the permafrost and the determination of their potential impact on future energy supplies, geohazard and climate change. We present results from a detailed seismic characterization of three gas hydrate horizons (A, B and C) intersected below the permafrost in five wells of the Mallik gas hydrate field located in the Mackenzie delta (Northwest Territories, Canada). The detailed seismic characterization included attribute analyses, synthetic modeling and acoustic impedance inversion and allowed estimation of the lateral continuity of the three horizons in the vicinity of the wells. Vertical Seismic Profiling (VSP) data, 3D and 2D industry seismic data and the 5L/2L-38 geophysical logs (density, P-wave sonic velocity) were used for this study. Synthetic modeling using the sonic and density logs reveals that the base of the lower gas hydrate horizons B and C can be identified on the industry 3D and 2D seismic sections as prominent isolated reflections. The uppermost gas hydrate occurrence (horizon A) and potentially other additional smaller-scale layers are identified only on the higher-resolution VSP data. The 3D industry seismic data set processed to preserve the relative true-amplitudes was used for attribute calculations and acoustic impedance inversion. The attribute maps defined areas of continuous reflectivity for horizons B and C and structural features disrupting them. Results from impedance inversion indicate that such continuous reflectivity around the wells is most likely attributable to gas hydrates. The middle gas hydrate occurrence (horizon B) covers an area of approximately 25 000m2. Horizon C, which marks the base of gas hydrate occurrence zone, extends over a larger area of approximately 120 000m2.

Non-seismic tsunamis: filling the forecast gap

NASA Astrophysics Data System (ADS)

Moore, C. W.; Titov, V. V.; Spillane, M. C.

2015-12-01

Earthquakes are the generation mechanism in over 85% of tsunamis. However, non-seismic tsunamis, including those generated by meteorological events, landslides, volcanoes, and asteroid impacts, can inundate significant area and have a large far-field effect. The current National Oceanographic and Atmospheric Administration (NOAA) tsunami forecast system falls short in detecting these phenomena. This study attempts to classify the range of effects possible from these non-seismic threats, and to investigate detection methods appropriate for use in a forecast system. Typical observation platforms are assessed, including DART bottom pressure recorders and tide gauges. Other detection paths include atmospheric pressure anomaly algorithms for detecting meteotsunamis and the early identification of asteroids large enough to produce a regional hazard. Real-time assessment of observations for forecast use can provide guidance to mitigate the effects of a non-seismic tsunami.

CORSSA: Community Online Resource for Statistical Seismicity Analysis

NASA Astrophysics Data System (ADS)

Zechar, J. D.; Hardebeck, J. L.; Michael, A. J.; Naylor, M.; Steacy, S.; Wiemer, S.; Zhuang, J.

2011-12-01

Statistical seismology is critical to the understanding of seismicity, the evaluation of proposed earthquake prediction and forecasting methods, and the assessment of seismic hazard. Unfortunately, despite its importance to seismology-especially to those aspects with great impact on public policy-statistical seismology is mostly ignored in the education of seismologists, and there is no central repository for the existing open-source software tools. To remedy these deficiencies, and with the broader goal to enhance the quality of statistical seismology research, we have begun building the Community Online Resource for Statistical Seismicity Analysis (CORSSA, www.corssa.org). We anticipate that the users of CORSSA will range from beginning graduate students to experienced researchers. More than 20 scientists from around the world met for a week in Zurich in May 2010 to kick-start the creation of CORSSA: the format and initial table of contents were defined; a governing structure was organized; and workshop participants began drafting articles. CORSSA materials are organized with respect to six themes, each will contain between four and eight articles. CORSSA now includes seven articles with an additional six in draft form along with forums for discussion, a glossary, and news about upcoming meetings, special issues, and recent papers. Each article is peer-reviewed and presents a balanced discussion, including illustrative examples and code snippets. Topics in the initial set of articles include: introductions to both CORSSA and statistical seismology, basic statistical tests and their role in seismology; understanding seismicity catalogs and their problems; basic techniques for modeling seismicity; and methods for testing earthquake predictability hypotheses. We have also begun curating a collection of statistical seismology software packages.

Theoretical and experimental investigation of position-controlled semi-active friction damper for seismic structures

NASA Astrophysics Data System (ADS)

Lu, Lyan-Ywan; Lin, Tzu-Kang; Jheng, Rong-Jie; Wu, Hsin-Hsien

2018-01-01

A semi-active friction damper (SAFD) can be employed for the seismic protection of structural systems. The effectiveness of an SAFD in absorbing seismic energy is usually superior to that of its passive counterpart, since its slip force can be altered in real time according to structural response and excitation. Most existing SAFDs are controlled by adjusting the clamping force applied on the friction interface. Thus, the implementation of SAFDs in practice requires precision control of the clamping force, which is usually substantially larger than the slip force. This may increase the implementation complexity and cost of SAFDs. To avoid this problem, this study proposes a novel position-controlled SAFD, named the leverage-type controllable friction damper (LCFD). The LCFD system combines a traditional passive friction damper and a leverage mechanism with a movable central pivot. By simply controlling the pivot position, the damping force generated by the LCFD system can be adjusted in real time. In order to verify the feasibility of the proposed SAFD, a prototype LCFD was tested by using a shaking table. The test results demonstrate that the equivalent friction force and hysteresis loop of the LCFD can be regulated by controlling the pivot position. By considering 16 ground motions with two different intensities, the adaptive feature of the LCFD for seismic structural control is further demonstrated numerically.

Two applications of time reversal mirrors: seismic radio and seismic radar.

PubMed

Hanafy, Sherif M; Schuster, Gerard T

2011-10-01

Two seismic applications of time reversal mirrors (TRMs) are introduced and tested with field experiments. The first one is sending, receiving, and decoding coded messages similar to a radio except seismic waves are used. The second one is, similar to radar surveillance, detecting and tracking a moving object(s) in a remote area, including the determination of the objects speed of movement. Both applications require the prior recording of calibration Green's functions in the area of interest. This reference Green's function will be used as a codebook to decrypt the coded message in the first application and as a moving sensor for the second application. Field tests show that seismic radar can detect the moving coordinates (x(t), y(t), z(t)) of a person running through a calibration site. This information also allows for a calculation of his velocity as a function of location. Results with the seismic radio are successful in seismically detecting and decoding coded pulses produced by a hammer. Both seismic radio and radar are highly robust to signals in high noise environments due to the super-stacking property of TRMs. © 2011 Acoustical Society of America

Retrieving both phase and amplitude information of Green's functions by ambient seismic wave field cross-correlation: A case study with a limestone mine induced seismic event

NASA Astrophysics Data System (ADS)

Kwak, S.; Song, S. G.; Kim, G.; Shin, J. S.

2015-12-01

Recently many seismologists have paid attention to ambient seismic field, which is no more referred as noise and called as Earth's hum, but as useful signal to understand subsurface seismic velocity structure. It has also been demonstrated that empirical Green's functions can be constructed by retrieving both phase and amplitude information from ambient seismic field (Prieto and Beroza 2008). The constructed empirical Green's functions can be used to predict strong ground motions after focal depth and double-couple mechanism corrections (Denolle et al. 2013). They do not require detailed subsurface velocity model and intensive computation for ground motion simulation. In this study, we investigate the capability of predicting long period surface waves by the ambient seismic wave field with a seismic event of Mw 4.0, which occurred with a limestone mine collapse in South Korea on January 31, 2015. This limestone-mine event provides an excellent opportunity to test the efficiency of the ambient seismic wave field in retrieving both phase and amplitude information of Green's functions due to the single force mechanism of the collapse event. In other words, both focal depth and double-couple mechanism corrections are not required for this event. A broadband seismic station, which is about 5.4 km away from the mine event, is selected as a source station. Then surface waves retrieved from the ambient seismic wave field cross-correlation are compared with those generated by the event. Our preliminary results show some potential of the ambient seismic wave field in retrieving both phase and amplitude of Green's functions from a single force impulse source at the Earth's surface. More comprehensive analysis by increasing the time length of stacking may improve the results in further studies. We also aim to investigate the efficiency of retrieving the full empirical Green's functions with the 2007 Mw 4.6 Odaesan earthquake, which is one of the strongest earthquakes occurred

A seismic survey of the Manson disturbed area

NASA Technical Reports Server (NTRS)

Sendlein, L. V. A.; Smith, T. A.

1971-01-01

The region in north-central Iowa referred to as the Manson disturbed area was investigated with the seismic refraction method and the bedrock configuration mapped. The area is approximately 30 km in diameter and is not detectable from the surface topography; however, water wells that penetrate the bedrock indicate that the bedrock is composed of disturbed Cretaceous sediments with a central region approximately 6 km in diameter composed of Precambrian crystalline rock. Seismic velocity differences between the overlying glacial till and the Cretaceous sediments were so small that a statistical program was developed to analyze the data. The program developed utilizes existing 2 segment regression analyses and extends the method to fit 3 or more regression lines to seismic data.

Seismic intrusion detector system

DOEpatents

Hawk, Hervey L.; Hawley, James G.; Portlock, John M.; Scheibner, James E.

1976-01-01

A system for monitoring man-associated seismic movements within a control area including a geophone for generating an electrical signal in response to seismic movement, a bandpass amplifier and threshold detector for eliminating unwanted signals, pulse counting system for counting and storing the number of seismic movements within the area, and a monitoring system operable on command having a variable frequency oscillator generating an audio frequency signal proportional to the number of said seismic movements.

Study on Seismicity of Sino-Mongolia Arc Areas

NASA Astrophysics Data System (ADS)

Xu, Guangyin; Wang, Suyun

2016-04-01

Using the earthquake catalogue from China, Mongolia and the global catalogue, the uniform catalogue of North China, Mongolia and adjacent areas, which is within the region 80-130°E, 40-55°N, has been established by Institute of Geophysics, China Earthquake Administration and Research Center of Astronomy and Geophysics, Mongolian Academy of Science for the seismic hazard analysis and seismic zoning map of Mongolia according to the following principles. 1) Earthquakes, which just exist in one catalogue, need to be verified further. If the earthquakes occurred in the country where the catalog comes from, then they will be adopted. If not, it should be checked with other more data. 2) The events that come from the three data sources have be checked and verified as followings. (1) The parameters of earthquakes that occurred in China will be taken from China catalog. (2)The parameters of earthquakes that occurred in Mongolia will be taken from Mongolia catalog. (3) The parameters of earthquakes that occurred in the adjacent areas will be taken from the global catalog by Song et al. According to the uniform catalogue, the seismicity of the North China, Mongolia and adjacent areas is analyzed, and the conclusions as followings are made. 1) The epicenter map can be roughly divided into two parts, bounded by the longitude line 105°E , in accordance with the "North-South Seismic Belt" of China. The seismicity is in a high level with many strong earthquakes in the west and is in a low level with little strong events in the east. 2) Most earthquakes are shallow-focus events, but there are also several middle or deep-focus events in the study area. 3) Earthquakes with magnitude greater than 5 are basically complete since 1450 A.D., and the seismicity of the study areas is in a high level since 1700 A. 4) Two seismic belts, Altay seismic belt and Bolnay-Baikal seismic belt, are determined according to the epicenters and tectonics. 5) The b-values of magnitude - frequency

Southern Appalachian Regional Seismic Network

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1994-08-01

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

Seismic properties of fluid bearing formations in magmatic geothermal systems: can we directly detect geothermal activity with seismic methods?

NASA Astrophysics Data System (ADS)

Grab, Melchior; Scott, Samuel; Quintal, Beatriz; Caspari, Eva; Maurer, Hansruedi; Greenhalgh, Stewart

2016-04-01

Seismic methods are amongst the most common techniques to explore the earth's subsurface. Seismic properties such as velocities, impedance contrasts and attenuation enable the characterization of the rocks in a geothermal system. The most important goal of geothermal exploration, however, is to describe the enthalpy state of the pore fluids, which act as the main transport medium for the geothermal heat, and to detect permeable structures such as fracture networks, which control the movement of these pore fluids in the subsurface. Since the quantities measured with seismic methods are only indirectly related with the fluid state and the rock permeability, the interpretation of seismic datasets is difficult and usually delivers ambiguous results. To help overcome this problem, we use a numerical modeling tool that quantifies the seismic properties of fractured rock formations that are typically found in magmatic geothermal systems. We incorporate the physics of the pore fluids, ranging from the liquid to the boiling and ultimately vapor state. Furthermore, we consider the hydromechanics of permeable structures at different scales from small cooling joints to large caldera faults as are known to be present in volcanic systems. Our modeling techniques simulate oscillatory compressibility and shear tests and yield the P- and S-wave velocities and attenuation factors of fluid saturated fractured rock volumes. To apply this modeling technique to realistic scenarios, numerous input parameters need to be indentified. The properties of the rock matrix and individual fractures were derived from extensive literature research including a large number of laboratory-based studies. The geometries of fracture networks were provided by structural geologists from their published studies of outcrops. Finally, the physical properties of the pore fluid, ranging from those at ambient pressures and temperatures up to the supercritical conditions, were taken from the fluid physics

Intraplate seismicity across the Cape Verde swell

NASA Astrophysics Data System (ADS)

Vales, Dina; Matias, Luís.; Haberland, Christian; Silveira, Graça.; Weber, Michael; Carrilho, Fernando; Dias, Nuno

2010-05-01

, to the SW. This activity was concentrated mainly during January 2008. The Brava and nearby Fogo Islands are known for their recent volcanic activity (last eruption in Fogo was in April 1995) and earthquake swarms. Therefore, we infer that the recorded seismic activity may be also triggered by magma flow. This study was funded by project "CV-PLUME: An investigation on the geometry and deep signature of the Cape Verde mantle plume", reference - PTDC/CTE-GIN/64330/2006; and Germany - "COBO: Cape Verdes Origin from Broadband Observations, GFZ, Geophysical Deep Sounding Section. The operation was possible thanks to the cooperation between the GeoForschungsZentrum Potsdam (Germany's National Research Centre for Geosciences) with the Instituto Dom Luiz.

Seismic Design of a Single Bored Tunnel: Longitudinal Deformations and Seismic Joints

NASA Astrophysics Data System (ADS)

Oh, J.; Moon, T.

2018-03-01

The large diameter bored tunnel passing through rock and alluvial deposits subjected to seismic loading is analyzed for estimating longitudinal deformations and member forces on the segmental tunnel liners. The project site has challenges including high hydrostatic pressure, variable ground profile and high seismic loading. To ensure the safety of segmental tunnel liner from the seismic demands, the performance-based two-level design earthquake approach, Functional Evaluation Earthquake and Safety Evaluation Earthquake, has been adopted. The longitudinal tunnel and ground response seismic analyses are performed using a three-dimensional quasi-static linear elastic and nonlinear elastic discrete beam-spring elements to represent segmental liner and ground spring, respectively. Three components (longitudinal, transverse and vertical) of free-field ground displacement-time histories evaluated from site response analyses considering wave passage effects have been applied at the end support of the strain-compatible ground springs. The result of the longitudinal seismic analyses suggests that seismic joint for the mitigation measure requiring the design deflection capacity of 5-7.5 cm is to be furnished at the transition zone between hard and soft ground condition where the maximum member forces on the segmental liner (i.e., axial, shear forces and bending moments) are induced. The paper illustrates how detailed numerical analyses can be practically applied to evaluate the axial and curvature deformations along the tunnel alignment under difficult ground conditions and to provide the seismic joints at proper locations to effectively reduce the seismic demands below the allowable levels.

Pre-seismic anomalies from optical satellite observations: a review

NASA Astrophysics Data System (ADS)

Jiao, Zhong-Hu; Zhao, Jing; Shan, Xinjian

2018-04-01

Detecting various anomalies using optical satellite data prior to strong earthquakes is key to understanding and forecasting earthquake activities because of its recognition of thermal-radiation-related phenomena in seismic preparation phases. Data from satellite observations serve as a powerful tool in monitoring earthquake preparation areas at a global scale and in a nearly real-time manner. Over the past several decades, many new different data sources have been utilized in this field, and progressive anomaly detection approaches have been developed. This paper reviews the progress and development of pre-seismic anomaly detection technology in this decade. First, precursor parameters, including parameters from the top of the atmosphere, in the atmosphere, and on the Earth's surface, are stated and discussed. Second, different anomaly detection methods, which are used to extract anomalous signals that probably indicate future seismic events, are presented. Finally, certain critical problems with the current research are highlighted, and new developing trends and perspectives for future work are discussed. The development of Earth observation satellites and anomaly detection algorithms can enrich available information sources, provide advanced tools for multilevel earthquake monitoring, and improve short- and medium-term forecasting, which play a large and growing role in pre-seismic anomaly detection research.

Searching for the corner seismic moment in worldwide data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Felgueiras, Miguel; Santos, Rui; Martins, João Paulo

2015-12-31

In this paper the existence of the corner frequency value for the seismic moment distribution is investigated, analysing worldwide data. Pareto based distributions, usually considered as the most suitable to this type of data, are fitted to the most recent data, available in a global earthquake catalog. Despite the undeniable finite nature of the seismic moment data, we conclude that no corner frequency can be established considering the available data set.

Method of migrating seismic records

DOEpatents

Ober, Curtis C.; Romero, Louis A.; Ghiglia, Dennis C.

2000-01-01

The present invention provides a method of migrating seismic records that retains the information in the seismic records and allows migration with significant reductions in computing cost. The present invention comprises phase encoding seismic records and combining the encoded seismic records before migration. Phase encoding can minimize the effect of unwanted cross terms while still allowing significant reductions in the cost to migrate a number of seismic records.

Core-seismic investigation of Surveyor Channel tributaries: Glacial history of the southern Alaskan margin

NASA Astrophysics Data System (ADS)

Somchat, K.; Reece, R.; Gulick, S. P. S.; Asahi, H.; Mix, A. C.

2016-12-01

The low angle subduction and collision of the Yakutat microplate with the North America Plate created, and continues to contribute to the uplift of the Chugach-St. Elias Range. This heavily glaciated, high topography proximal to the shoreline creates a unique source-to-sink system in which glacial sediment is transported and preserved offshore in a deep sea fan without much interruption. The product of this sediment is the Surveyor Fan and Channel system. Four tributary channels form the head of the Surveyor Channel complex and merge into the main channel trunk 200 km from the shelf edge. We integrate drill core and seismic reflection data to study the evolution of these tributaries in order to decipher glacial history of the southern Alaskan margin since the mid-Pleistocene (1.2 Ma). Updated age models from Integrated Ocean Drilling Program Expedition 341 Sites U1417 and U1418 provide a higher resolution chronology of sediment delivery to the Surveyor Fan than previous studies. We regionally extended the mapping of seismic subunits previously identified by Exp. 341 scientists at sites U1417 and U1418 and analyzed regional patterns of sediment deposition. Two-way travel time (isopach) maps of the three subunits show a trend of sediment depocenter shifting to the east since 1.2 Ma, where the Yakutat and Alsek tributaries have increasing sediment flux through time. Changes in sediment flux in each system represent the changes in locations and amplitudes of glacial ice over successive glacial intervals. Additionally, seismic analysis of channel geomorphology shows that each system contains distinct geomorphological evolutions. Since glacial erosion provides the sediment for the fan, the history of glacial ice onshore can be inferred from seismic geomorphology, where changes in glacial ice affect sediment supply and therefore shifts in depocenters and sedimentation pathways. This study shows an interaction between glacial activity onshore and deep sea fan sediment

Experimental study on the seismic performance of new sandwich masonry walls

NASA Astrophysics Data System (ADS)

Xiao, Jianzhuang; Pu, Jie; Hu, Yongzhong

2013-03-01

Sandwich masonry walls are widely used as energy-saving panels since the interlayer between the outer leaves can act as an insulation layer. New types of sandwich walls are continually being introduced in research and applications, and due to their unique bond patterns, experimental studies have been performed to investigate their mechanical properties, especially with regard to their seismic performance. In this study, three new types of sandwich masonry wall have been designed, and cyclic lateral loading tests were carried out on five specimens. The results showed that the specimens failed mainly due to slippage along the bottom cracks or the development of diagonal cracks, and the failure patterns were considerably influenced by the aspect ratio. Analysis was undertaken on the seismic response of the new walls, which included ductility, stiffness degradation and energy dissipation capacity, and no obvious difference was observed between the seismic performance of the new walls and traditional walls. Comparisons were made between the experimental results and the calculated results of the shear capacity. It is concluded that the formulas in the two Chinese codes (GB 50011 and GB 50003) are suitable for the calculation of the shear capacity for the new types of walls, and the formula in GB 50011 tends to be more conservative.

The availability of hydrogeologic data associated with areas identified by the US Geological Survey as experiencing potentially induced seismicity resulting from subsurface injection

NASA Astrophysics Data System (ADS)

Barnes, Caitlin; Halihan, Todd

2018-05-01

A critical need exists for site-specific hydrogeologic data in order to determine potential hazards of induced seismicity and to manage risk. By 2015, the United States Geological Survey (USGS) had identified 17 locations in the USA that are experiencing an increase in seismicity, which may be potentially induced through industrial subsurface injection. These locations span across seven states, which vary in geological setting, industrial exposure and seismic history. Comparing the research across the 17 locations revealed patterns for addressing induced seismicity concerns, despite the differences between geographical locations. Most induced seismicity studies evaluate geologic structure and seismic data from areas experiencing changes in seismic activity levels, but the inherent triggering mechanism is the transmission of hydraulic pressure pulses. This research conducted a systematic review of whether data are available in these locations to generate accurate hydrogeologic predictions, which could aid in managing seismicity. After analyzing peer-reviewed research within the 17 locations, this research confirms a lack of site-specific hydrogeologic data availability for at-risk areas. Commonly, formation geology data are available for these sites, but hydraulic parameters for the seismically active injection and basement zones are not available to researchers conducting peer-reviewed research. Obtaining hydrogeologic data would lead to better risk management for injection areas and provide additional scientific evidential support for determining a potentially induced seismic area.

A comparative study of two statistical approaches for the analysis of real seismicity sequences and synthetic seismicity generated by a stick-slip experimental model

NASA Astrophysics Data System (ADS)

Flores-Marquez, Leticia Elsa; Ramirez Rojaz, Alejandro; Telesca, Luciano

2015-04-01

The study of two statistical approaches is analyzed for two different types of data sets, one is the seismicity generated by the subduction processes occurred at south Pacific coast of Mexico between 2005 and 2012, and the other corresponds to the synthetic seismic data generated by a stick-slip experimental model. The statistical methods used for the present study are the visibility graph in order to investigate the time dynamics of the series and the scaled probability density function in the natural time domain to investigate the critical order of the system. This comparison has the purpose to show the similarities between the dynamical behaviors of both types of data sets, from the point of view of critical systems. The observed behaviors allow us to conclude that the experimental set up globally reproduces the behavior observed in the statistical approaches used to analyses the seismicity of the subduction zone. The present study was supported by the Bilateral Project Italy-Mexico Experimental Stick-slip models of tectonic faults: innovative statistical approaches applied to synthetic seismic sequences, jointly funded by MAECI (Italy) and AMEXCID (Mexico) in the framework of the Bilateral Agreement for Scientific and Technological Cooperation PE 2014-2016.

Ultrasonic laboratory measurements of the seismic velocity changes due to CO2 injection

NASA Astrophysics Data System (ADS)

Park, K. G.; Choi, H.; Park, Y. C.; Hwang, S.

2009-04-01

Monitoring the behavior and movement of carbon dioxide (CO2) in the subsurface is a quite important in sequestration of CO2 in geological formation because such information provides a basis for demonstrating the safety of CO2 sequestration. Recent several applications in many commercial and pilot scale projects and researches show that 4D surface or borehole seismic methods are among the most promising techniques for this purpose. However, such information interpreted from the seismic velocity changes can be quite subjective and qualitative without petrophysical characterization for the effect of CO2 saturation on the seismic changes since seismic wave velocity depends on various factors and parameters like mineralogical composition, hydrogeological factors, in-situ conditions. In this respect, we have developed an ultrasonic laboratory measurement system and have carried out measurements for a porous sandstone sample to characterize the effects of CO2 injection to seismic velocity and amplitude. Measurements are done by ultrasonic piezoelectric transducer mounted on both ends of cylindrical core sample under various pressure, temperature, and saturation conditions. According to our fundamental experiments, injected CO2 introduces the decrease of seismic velocity and amplitude. We identified that the velocity decreases about 6% or more until fully saturated by CO2, but the attenuation of seismic amplitude is more drastically than the velocity decrease. We also identified that Vs/Vp or elastic modulus is more sensitive to CO2 saturation. We note that this means seismic amplitude and elastic modulus change can be an alternative target anomaly of seismic techniques in CO2 sequestration monitoring. Thus, we expect that we can estimate more quantitative petrophysical relationships between the changes of seismic attributes and CO2 concentration, which can provide basic relation for the quantitative assessment of CO2 sequestration by further researches.

Seismic source parameters of the induced seismicity at The Geysers geothermal area, California, by a generalized inversion approach

NASA Astrophysics Data System (ADS)

Picozzi, Matteo; Oth, Adrien; Parolai, Stefano; Bindi, Dino; De Landro, Grazia; Amoroso, Ortensia

2017-04-01

The accurate determination of stress drop, seismic efficiency and how source parameters scale with earthquake size is an important for seismic hazard assessment of induced seismicity. We propose an improved non-parametric, data-driven strategy suitable for monitoring induced seismicity, which combines the generalized inversion technique together with genetic algorithms. In the first step of the analysis the generalized inversion technique allows for an effective correction of waveforms for the attenuation and site contributions. Then, the retrieved source spectra are inverted by a non-linear sensitivity-driven inversion scheme that allows accurate estimation of source parameters. We therefore investigate the earthquake source characteristics of 633 induced earthquakes (ML 2-4.5) recorded at The Geysers geothermal field (California) by a dense seismic network (i.e., 32 stations of the Lawrence Berkeley National Laboratory Geysers/Calpine surface seismic network, more than 17.000 velocity records). We find for most of the events a non-selfsimilar behavior, empirical source spectra that requires ωγ source model with γ > 2 to be well fitted and small radiation efficiency ηSW. All these findings suggest different dynamic rupture processes for smaller and larger earthquakes, and that the proportion of high frequency energy radiation and the amount of energy required to overcome the friction or for the creation of new fractures surface changes with the earthquake size. Furthermore, we observe also two distinct families of events with peculiar source parameters that, in one case suggests the reactivation of deep structures linked to the regional tectonics, while in the other supports the idea of an important role of steeply dipping fault in the fluid pressure diffusion.

South-Central Tibetan Seismicity from HiCLIMB Seismic Array Data

NASA Astrophysics Data System (ADS)

Carpenter, S.; Nabelek, J.; Braunmiller, J.

2010-12-01

The HiCLIMB broadband passive seismic experiment (2002-2005) operated 233 sites along a 800-km long north-south array extending from the Himalayan foreland into the Central Tibetan Plateau and a flanking 350x350 km lateral array in southern Tibet and eastern Nepal. We use data from the experiment’s second phase (June 2004 to August 2005), when stations operated in Tibet, to locate earthquakes in south-central Tibet, a region with no permanent seismic network where little is known about its seismicity. We used the Antelope software for automatic detection and arrival time picking, event-arrival association and event location. Requiring a low detection and event association threshold initially resulted in ~110,000 declared events. The large database size rendered manual inspection unfeasible and we developed automated post-processing modules to weed out spurious detections and erroneous phase and event associations, which stemmed, e.g., from multiple coincident earthquakes within the array or misplaced seismicity from the great 2004 Sumatra earthquake. The resulting database contains ~32,000 events within 5° distance from the closest station. We consider ~7,600 events defined by more than 30 P and S arrivals well located and discuss them here. Seismicity in the subset correlates well with mapped faults and structures seen on satellite imagery attesting to high location quality. This is confirmed by non-systematic, kilometer-scale differences between automatic and manual locations for selected events. Seismicity in south-central Tibet is intense north of the Yarlung-Tsangpo Suture. Almost 90% of events occurred in the Lhasa Terrane mainly along north-south trending rifts. Vigorous activity (>4,800 events) accompanied two M>6 earthquakes in the Payang Basin (84°E), ~100 km west of the linear array. The Tangra-Yum Co (86.5°E) and Pumqu-Xianza (88°E) rifts were very active (~1,000 events) without dominant main shocks indicating swarm like-behavior possibly related

Seismic-wave attenuation associated with crustal faults in the New Madrid seismic zone

USGS Publications Warehouse

Hamilton, R.M.; Mooney, W.D.

1990-01-01

The attenuation of upper crustal seismic waves that are refracted with a velocity of about 6 kilometers per second varies greatly among profiles in the area of the New Madrid seismic zone in the central Mississippi Valley. The waves that have the strongest attenuation pass through the seismic trend along the axis of the Reelfoot rift in the area of the Blytheville arch. Defocusing of the waves in a low-velocity zone and/ or seismic scattering and absorption could cause the attenuation; these effects are most likely associated with the highly deformed rocks along the arch. Consequently, strong seismic-wave attenuation may be a useful criterion for identifying seismogenic fault zones.

Seismic sounding of convection in the Sun

NASA Astrophysics Data System (ADS)

Sreenivasan, Katepalli R.

2015-11-01

Thermal convection is the dominant mechanism of energy transport in the outer envelope of the Sun (one-third by radius). It drives global fluid circulations and magnetic fields observed on the solar surface. Convection excites a broadband spectrum of acoustic waves that propagate within the interior and set up modal resonances. These acoustic waves, also called seismic waves, are observed at the surface of the Sun by space- and ground-based telescopes. Seismic sounding, the study of these seismic waves to infer the internal properties of the Sun, constitutes helioseismology. Here we review our knowledge of solar convection, especially that obtained through seismic inference. Several characteristics of solar convection, such as differential rotation, anisotropic Reynolds stresses, the influence of rotation on convection and supergranulation, are considered. On larger scales, several inferences suggest that convective velocities are substantially smaller than those predicted by theory and simulations. This discrepancy challenges the models of internal differential rotation that rely on convective stresses as a driving mechanism and provide an important benchmark for numerical simulations. In collaboration with Shravan Hanasoge, Tata Institute of Fundamental Research, Mumbai and Laurent Gizon, Max-Planck-Institut fuer Sonnensystemforschung, Goettingen.

Seismic hazard assessment: Issues and alternatives

USGS Publications Warehouse

Wang, Z.

2011-01-01

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

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

NASA Astrophysics Data System (ADS)

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.

Excavatability Assessment of Weathered Sedimentary Rock Mass Using Seismic Velocity Method

NASA Astrophysics Data System (ADS)

Bin Mohamad, Edy Tonnizam; Saad, Rosli; Noor, Muhazian Md; Isa, Mohamed Fauzi Bin Md.; Mazlan, Ain Naadia

2010-12-01

Seismic refraction method is one of the most popular methods in assessing surface excavation. The main objective of the seismic data acquisition is to delineate the subsurface into velocity profiles as different velocity can be correlated to identify different materials. The physical principal used for the determination of excavatability is that seismic waves travel faster through denser material as compared to less consolidated material. In general, a lower velocity indicates material that is soft and a higher velocity indicates more difficult to be excavated. However, a few researchers have noted that seismic velocity method alone does not correlate well with the excavatability of the material. In this study, a seismic velocity method was used in Nusajaya, Johor to assess the accuracy of this seismic velocity method with excavatability of the weathered sedimentary rock mass. A direct ripping run by monitoring the actual production of ripping has been employed at later stage and compared to the ripper manufacturer's recommendation. This paper presents the findings of the seismic velocity tests in weathered sedimentary area. The reliability of using this method with the actual rippability trials is also presented.

Very-long-period seismic signals - filling the gap between deformation and seismicity

NASA Astrophysics Data System (ADS)

Neuberg, Jurgen; Smith, Paddy

2013-04-01

Good broadband seismic sensors are capable to record seismic transients with dominant wavelengths of several tens or even hundreds of seconds. This allows us to generate a multi-component record of seismic volcanic events that are located in between the conventional high to low-frequency seismic spectrum and deformation signals. With a much higher temporal resolution and accuracy than e.g. GPS records, these signals fill the gap between seismicity and deformation studies. In this contribution we will review the non-trivial processing steps necessary to retrieve ground deformation from the original velocity seismogram and explore which role the resulting displacement signals have in the analysis of volcanic events. We use examples from Soufriere Hills volcano in Montserrat, West Indies, to discuss the benefits and shortcomings of such methods regarding new insights into volcanic processes.

Storage of fluids and melts at subduction zones detectable by seismic tomography

NASA Astrophysics Data System (ADS)

Luehr, B. G.; Koulakov, I.; Rabbel, W.; Brotopuspito, K. S.; Surono, S.

2015-12-01

During the last decades investigations at active continental margins discovered the link between the subduction of fluid saturated oceanic plates and the process of ascent of these fluids and partial melts forming a magmatic system that leads to volcanism at the earth surface. For this purpose the geophysical structure of the mantle and crustal range above the down going slap has been imaged. Information is required about the slap, the ascent paths, as well as the reservoires of fluids and partial melts in the mantle and the crust up to the volcanoes at the surface. Statistically the distance between the volcanoes of volcanic arcs down to their Wadati Benioff zone results of approximately 100 kilometers in mean value. Surprisingly, this depth range shows pronounced seismicity at most of all subduction zones. Additionally, mineralogical laboratory investigations have shown that dehydration of the diving plate has a maximum at temperature and pressure conditions we find at around 100 km depth. The ascent of the fluids and the appearance of partial melts as well as the distribution of these materials in the crust can be resolved by seismic tomographic methods using records of local natural seismicity. With these methods these areas are corresponding to lowered seismic velocities, high Vp/Vs ratios, as well as increased attenuation of seismic shear waves. The anomalies and their time dependence are controlled by the fluids. The seismic velocity anomalies detected so far are within a range of a few per cent to more than 30% reduction. But, to explore plate boundaries large and complex amphibious experiments are required, in which active and passive seismic investigations should be combined to achieve best results. The seismic station distribution should cover an area from before the trench up to far behind the volcanic chain, to provide under favorable conditions information down to 150 km depth. Findings of different subduction zones will be compared and discussed.