| Analysis of Digitized Seismograms from Russian Geophysical Survey Stations of Soviet Peaceful Nuclear Explosions |
30-Sep-2009 |
11 pages |
| Authors:
Kevin G Mackey; Hans E Hartse; MICHIGAN STATE UNIV EAST LANSING
|
 | Throughout the 1970s and 1980s, the permanent seismic stations of the Soviet Union recorded over 100 peaceful nuclear explosions (PNEs) detonated within the Soviet Union. These records represent a large data set that has not been fully utilized. Digitization and analysis of the historic seismograms has allowed the extension of long-range PNE profile data into geographic regions not previously covered. Although the resolution of the profiles is limited by the ... |
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| Seismo-Acoustic Generation by Earthquakes and Explosions and Near-Regional Propagation |
30-Sep-2009 |
10 pages |
| Authors:
Relu Burlacu; Kristine Pankow; Tae-Sung Kim; Stephen J Arrowsmith; Brian W Stump; Christopher T Hayward; Rongmao Zhou; SOUTHERN METHODIST UNIV DALLAS TX
|
| Seismo-acoustic measurements provide an opportunity to quantify natural and man-made sources that are at or near the Earth's surface. We have operated three acoustic arrays collocated with seismometers from the University of Utah Seismograph Stations (BGU, EPU, NOQ). We report on progress in three separate areas of research related to these seismo-acoustic databases. The first topic investigates seismo-acoustic signals from the Wells, Nevada earthquake that occurred on February 21, 2008 ... |
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| Crustal Structure of the Iran Region from In-Country and Ground-Truth Data |
30-Sep-2008 |
8 pages |
| Authors:
Eric A Bergman; Eric R Engdahl; Michael H Ritzwoller; Stephen C Myers; COLORADO UNIV AT BOULDER
|
| We are investigating the crustal and upper mantle structure of the Iran region using in-country data sets of seismic phase arrival times, supplemented by ground-truth data sets developed from our previous research efforts. Other data sets from global, regional, and national bulletins in the region are being integrated as well. The in-country data sets, covering approximately the last 10 years of seismicity in the region, are being carefully reviewed for ... |
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| Initial Steps Toward Next-Generation, Waveform-Based, Three-Dimensional Models and Metrics to Improve Nuclear Explosion Monitoring in the Middle East |
30-Sep-2008 |
8 pages |
| Authors:
Brian Savage; Arthur J Rodgers; Jeroen Tromp; Brian Covellone; RHODE ISLAND UNIV KINGSTON
|
| In an effort toward improving current seismic-velocity models for the Middle East, the initial Step of building a high-quality database of recordings from well characterized sources is essential. This high-quality database of recordings, or broadband waveforms, encompassing the region from the Mediterranean to the eastern edge of Tibet, will be the primary measure for evaluation and improvement in the iterative, waveform-based, adjoint-inversion process. Adjoint inversions, as with any waveform-based method, ... |
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| Finite-Frequency Seismic Tomography of Body Waves and Surface Waves from Ambient Seismic Noise: Crustal and Mantle Structure Beneath Eastern Eurasia |
30-Sep-2008 |
11 pages |
| Authors:
Wei Zhang; Xiaoping Yang; Yong Ren; Ting Yang; Yang Shen; SCIENCE APPLICATIONS INTERNATIONAL CORP SAN DIEGO CA
|
| To improve seismic calibration for nuclear explosion monitoring, we use 3D sensitivity kernels of finite-frequency body and surface waves to develop models of the crustal and mantle structures beneath eastern Eurasia. We have collected and processed available broadband data from both permanent stations and temporary networks in eastern Eurasia. We obtained a regional P-wave velocity model for the mantle structures down to 1,500 km beneath the eastern Eurasia. We also ... |
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| Surface Wave Dispersion Measurements and Tomography from Ambient Seismic Noise Correlation in China |
30-Sep-2008 |
12 pages |
| Authors:
Zhen Xu; Xiaodong Song; Michael H Ritzwoller; Xinlei Sun; Sihua Zheng; Yingjie Yang; ILLINOIS UNIV AT URBANA-CHAMAPIGN
|
| We perform ambient noise tomography of China using the data from the China National Seismic Network and global and PASSCAL stations. The results so far are summarized below. (1) Dispersion measurements and tomography. For most of the station pairs, we retrieve good Rayleigh waveforms from ambient noise correlations using 18 months of continuous data at all distance ranges across the entire region (over 5000 km) and for periods from 70 ... |
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| High-Resolution Seismic Velocity and Attenuation Structure of the Sichuan-Yunnan Region, Southwest China, Using Seismic Catalog and Waveform Data |
13 JUL 2007 |
62 pages |
| Authors:
Haijiang Zhang; Yunfeng Liu; Clifford H. Thurber; Zhen Xu; Xiaodong Song; WISCONSIN UNIV-MADISON
|
| The Sichuan-Yunnan region in southwestern China lies in the transition zone between the uplifted Tibetan plateau to the west and the Yangtze continental platform to the east. This region has a very complicated geological structure and is one of the most active areas of continental earthquakes in the world. This two-year project is to develop high-resolution models of the velocity and attenuation structure of the Sichuan-Yunnan region (longitudes ~97-108 degrees ... |
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| Discrepancies Between Prototype International Data Centre, International Seismological Centre & USGS Seismic Magnitudes |
MAR 2007 |
66 pages |
| Authors:
Paul G. Richards; John P. Granville; Won-Young Kim; COLUMBIA UNIV PALISADES NY LAMONT-DOHERTY EARTH OBSERVATORY
|
| A discrepancy between body-wave magnitudes, from the Prototype International Data Centre (PIDC) and the U.S. Geological Survey (USGS), has persisted since 1995, and amounts to a few tenths of a magnitude unit. Since 1999 we have studied the discrepancy between magnitudes published by different agencies and this final report is comprised of two sections. The first, is a stand-alone paper (published in the 2002 November/December issue of the Seismological Society ... |
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| Condition Assessment of Levees, U.S. Section of the International Boundary and Water Commission. Report 5: Flood Simulation Study of Retamal Levee, Lower Rio Grande Valley, Texas, Using Seismic and Electrical Geophysical Models |
JAN 2007 |
332 pages |
| Authors:
Joseph B. Dunbar; Jose L. Llopis; George L. Sills; Eric W. Smith; Rick D. Miller; Julian Ivanov; Robert F. Corwin; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
|
| In November 2004, a team from the U.S. Army Engineer Research and Development Center conducted a ponding test on a reach of the Retamal levee in the Lower Rio Grande Valley to simulate performance of the levee during a flood event. The work was performed for and with the assistance of the International Boundary and Water Commission, U.S. Section, on a levee reach with a significant number of surface cracks. ... |
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| Detection of Atmospheric Explosions at IMS Monitoring Stations using Infrasound Techniques |
SEP 2006 |
12 pages |
| Authors:
Douglas R. Christie; Brian L. Kennett; Chris Tarlowski; AUSTRALIAN NATIONAL UNIV CANBERRA
|
| Work is continuing on the development of infrasound techniques that can be used to improve detection, location and discrimination capability for atmospheric nuclear explosions at International Monitoring System (IMS) infrasound monitoring stations. In particular, we are continuing to focus on the detection of atmospheric explosions in the distance range from about 500 to 4500 km. We note that good detection capability in this distance range is essential to ensure that ... |
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| A Regional Seismic Experiment in India to Increase Knowledge of Velocity Structure |
MAY 2006 |
170 pages |
| Authors:
James F. Lewkowicz; Keith Priestley; Vinod Gaur; Jessie L. Bonner; Sara G. Russell; Delaine Ritter; Alessia Maggi; Supryio Mitra; WESTON GEOPHYSICAL LEXINGTON MA
|
| Weston Geophysical Corporation, Cambridge University and India Institute of Astrophysics formed a consortium in 2000 to deploy a network of high-quality broadband seismometers distributed across India. This network began operation in April 2001, and is now fully operational providing important data for studies focusing on the characterization of the velocity structure and propagation of seismic waves throughout Southern Asia. Each station consists of a Guralp CMG-3TD digital output seismometer plus ... |
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| Station Calibration and Regionalization in China and Surrounding Areas |
JAN 2005 |
72 pages |
| Authors:
Thomas Hearn; James Ni; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| NMSU seismologists, in conjunction with seismologists from the Institute of Geophysics of the China Seismological Bureau (IG/CSB), have collected seismic data to calibrate International Monitoring System stations in China and document propagation characteristics of regional phases in China. Much of the work is focused on the Annual Bulletin of Chinese Earthquakes. We obtained copies of these bulletins for 1983-1995. A tomographic image of Pn velocity beneath China was made and ... |
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| Seismological and Lithospheric Studies of the Libya Region |
DEC 2004 |
71 pages |
| Authors:
W. A. Brown; D. I. Doser; T. F. VanDeMark; A. A. Velasco; G. R. Keller; TEXAS UNIV AT EL PASO
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| This report constitutes an integrated geophysical investigation of the lithospheric structure in the region of Libya. I' is separated into five sections. The final four sections represent papers that will be submitted to different scientific journals for publication. In the first part of the study, we utilized a seamless mosaicking approach based on the commercial Environment for Visualizing Images (ENVI) software package to create mosaics of two geologically interesting portions ... |
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| Quantifying Source Excitation and Path Effects for High Frequency Regional Waves |
01 OCT 2004 |
59 pages |
| Authors:
Ru-Shan Wu; Xiao-Bi Xie; Thorne Lay; CALIFORNIA UNIV SANTA CRUZ
|
| This research is directed at investigation of regional wave excitation and propagation in complicated crustal waveguides using numerical simulations. The report covers three major approaches: (1) A finite-difference plus slowness analysis method for investigating near-source Lg-wave excitation and partitioning; (2) The half-space screen method for simulating high frequency Lg-wave propagation; and (3) A boundaty element method for calculating Lg-wave propagation in the crustal waveguide with uneven surface topography. |
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| Location, Characterization and Quantification of Hydroacoustic Signals in the Indian Ocean |
OCT 2004 |
60 pages |
| Authors:
M. Tolstoy; D. R. Bohnenstiehl; LAMONT-DOHERTY EARTH OBSERVATORY PALISADES NY
|
| In this final report we summarize research accomplished on the project titled, Location, Characterization and Quantification of Hydroacoustic Signals in the Indian Ocean. Our initial goals were to locate, characterize and quantify hydroacoustic signals recorded on the three available hydroacoustic stations in the Indian Ocean, and this was accomplished for available data through May 2003. However, shortly thereafter our contract was rescoped to focus on high frequency propagation through the ... |
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| The Evolution of Lithospheric Deformation and Crustal Structure from Continental Margins to Oceanic Spreading Centers |
JUN 2002 |
|
| Authors:
Mark D. Behn; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
 | This thesis investigates the evolution of lithospheric deformation and crustal structure from continental margins to mid-ocean ridges. The first part (Ch. 2) examines the style of segmentation along the U.S. East Coast Margin and investigates the relationship between incipient margin structure and segmentation at the modern Mid-Atlantic Ridge. The second part (Chs. 3-5) focuses on the mechanics of faulting in extending lithosphere. In Ch. 3, 1 show that the incorporation ... |
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| A Rolling Line Source for a Seismic Sonar |
JUN 2002 |
84 pages |
| Authors:
Scott C. McClelland; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| This thesis builds on ideas of a seismo-acoustic sonar as a mine detection tool and is part of an ongoing Naval Postgraduate School (NPS) research project. Building on this foundation of research, a source was developed to enable mobility. The previous NPS array Sheetz design employed an array of sources, buried in the sediment in a line. This arrangement is somewhat cumbersome for direct application. A practical device should be ... |
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| Recent Sedimentation and Stratigraphic Development in the Arabian Gulf |
DEC 2001 |
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| Authors:
Stephen A. Swift; David A. Ross; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF GEOLOGY AND GEOPHYSICS
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| The Persian/Arabian Gulf is subsiding in response to the collision between the Arabian and Asian plates and to growth during the last 5-10 years of the Zagros mountains. Uplifted fold belts, thickened continental crust, and poorly understood subcrustal loads depress the northeast edge of the Arabian plate creating, by lithospheric plate flexure, a foreland basin that is filled to the southeast with the shallow Gulf sea and to the northwest ... |
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| Analysis of Digital Teleseismic Array Data Collected in South Central Siberia and Northern Mongolia, GSN SKS Waves and S Waves from Lop Nor Nuclear Explosions |
02 JAN 2001 |
80 pages |
| Authors:
Paul M. Davis; Shangxing Gao; Laura Borton; CALIFORNIA UNIV LOS ANGELES DEPT OF EARTH AND SPACE SCIENCES
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| Analysis of data we collected in south central Siberia and Northern Mongolia along with digital data from the Global Seismic Network have been analyzed to identify effects on propagation of large scale heterogeneity in the mantle that need to be taken into account when using seismic arrays to monitor the Comprehensive Test Ban Treaty. We find that in the vicinity of the Baikal rift zone in Siberia, P and S ... |
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| Magmatism and Dynamics of Continental Breakup in the Presence of a Mantle Plume |
FEB 2000 |
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| Authors:
Jun Korenaga; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| This thesis studies the dynamics of mantle melting during continental breakups by geophysical, geochemical, and numerical analyses. The first part focuses on the mantle melting and crustal accretion processes during the formation of the Southeast Greenland margin, on the basis of deep-crustal seismic data. A seismic tomographic method is developed to jointly invert refraction and reflection travel times for a compressional velocity structure. Together with ... |
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| Seismic Acoustic Ratio Estimates Using a Moving Vehicle Source |
AUG 1999 |
14 pages |
| Authors:
Roy Greenfield; mark Moran; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF GEOSCIENCES
|
| Seismic and acoustic noise from moving tracked vehicles was used to determine the seismic to acoustic signal coupling ratio (SAR) in the ground. The seismic signal received on a geophone contains some energy that has propagated as seismic waves and some energy that couples from acoustic waves to seismic waves in the vicinity of the geophone. We use the frequency domain coherence between the microphone and geophone signals to determine ... |
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| Broadband Seismic Characterization of the Arabian Shield |
07 OCT 1998 |
46 pages |
| Authors:
Frank L. Vernon; Jonathan Berger; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA INST OF GEOPHYSICS AND PLANETARY PHYSICS
|
| From November 1995 to March 1997 a total of nine broadband temporary stations were deployed across the Saudi Arabian shield. These stations consisted of STS-2 seismometers that recorded continuously at 40 sps on Refraction Technology RT72A-07 dataloggers. All installations were at bedrock sites. The results from our field deployment of nine portable broadband stations suggest that sites in the Arabian shield are extremely quiet with ground noise near or equal ... |
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| Wave Propagation in the Arabian Plate |
28 JUN 1998 |
63 pages |
| Authors:
R. B. Herrmann; T. A. Mokhtar; T. M. Chang; C. J. Ammon; H. A. Ghalib; SAINT LOUIS UNIV MO DEPT OF EARTH AND ATMOSPHERIC SCIENCES
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| This report presents a tomographic analysis of surface-wave group velocity dispersion through the Arabian Plate and studies on the usefulness of genetic algorithms for the inversion of surface-wave waveforms for earth structure. The raw group velocity dispersion measurements are available by anonymous ftp to ftp.eas.slu.edu in the directory pub/rbh/ARABIA. |
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| Stratigraphic Development of the Central Persian Gulf During the Neogene |
07 APR 98 |
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| Authors:
Stephen A. Swift; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF GEOLOGY AND GEOPHYSICS
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| Industry seismic reflection profiles shot in the 60's and early 70's in the central Persian (Arabian) Gulf are used to map two late Tertiary unconformities, and velocity data from a centrally located well is used to convert travel time to depth to the unconformities. The deeper horizon correlates with a regional unconformity at the end of the Eocene in most wells and dips monotonically to ... |
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| Nonlinear Nearfield Wave Propagation in an Endochronic Solid |
APR 1998 |
79 pages |
| Authors:
Steven M. Day; J. B. Minster; Heming Xu; SAN DIEGO STATE UNIV CA DEPT OF GEOLOGICAL SCIENCES
|
| CTBT verification requires an understanding of the propagation of seismic phases over complex regional paths which cut across major structural boundaries. The computation of synthetic seismograms by finite difference methods plays an important role in developing such understanding. In order for synthetic seismograms to be realistic, the models must account not only for regional elastic structure of the path, but also for anelastic losses. In ... |
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| Synthetic Seismograms in Heterogeneous Elastic Waveguides and Applications in Investigating LG-Wave Propagation |
20 MAR 1998 |
48 pages |
| Authors:
R. S. Wu; S. Jin; X. B. Xie; T. Lay; CALIFORNIA UNIV SANTA CRUZ INST OF TECTONICS
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| This study is aimed at development and application of a new wave propagation and modeling method for regional waves in heterogeneous crustal waveguides using one-way wave approximation. As the first step, we solve the 2D SH-wave problem. A half-space GSP (Generalized Screen Propagator) is formulated for the SH half space problem. We apply our method to simulating regional wave propagation in different types of complex crustal waveguides including those with ... |
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| Broadband Seismic Characterization of the Arabian Shield |
FEB 1998 |
49 pages |
| Authors:
J. E. Zollweg; Dean M. Childs; BOISE STATE UNIV ID DEPT OF GEOSCIENCES
|
| Seismograms recorded on broadband instruments in Saudi Arabia for events occurring in the Zagros Folded Belt of Iran often show a P phase with an apparent velocity of about 5.7 km/sec. We refer to this phase as P(x). Its amplitude rapidly diminishes along Arabian Shield paths, suggesting it is a guided wave in the sedimentary section of the Arabian Platform. P(x) blockage is observed for event-station paths crossing the Zagros ... |
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| Seismic Sources in China and Korea |
FEB 1998 |
71 pages |
| Authors:
Paul G. Richards; Won-Yong Kim; LAMONT-DOHERTY EARTH OBSERVATORY PALISADES NY
|
| This final report is in four parts, consisting of: (1) a five-page summary of Ph. D. thesis of Jinghua Shi entitled "Quantification of Earthquakes based on Improved Estimates of Energy using Regional Waves"; (2) an application of methods developed by this thesis, to estimate the spatial variability of seismic wave attenuation in Western China; (3) a description of an unusual swarm of seismic activity in Western China; and (4) a ... |
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| Crustal Waveguide Effects on Regional Phases in China and Southeast Asia |
01 DEC 97 |
149 pages |
| Authors:
Thorne Lay; Guangwei Fan; Arthur Rodgers; CALIFORNIA UNIV SANTA CRUZ INST OF TECTONICS
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| This research program addressed the issue of reducing scatter in regional phase discriminant measures associated with waveguide irregularity. We empirically reduce discriminant measure variance, using along path measures obtained from data bases for surface topography, crustal thickness, and sedimentary layer thickness. Several path specific measures are found to have significant correlations with regional discriminant measurements, both before and after correction for propagation distance, for ... |
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| Semiannual Technical Summary, 1 April - 30 September 1997 |
NOV 1997 |
148 pages |
| Authors:
NORWEGIAN SEISMIC ARRAY (NORSAR) KJELLER
|
| This Semiannual Technical Summary describes the operation, maintenance and research activities at the Norwegian Seismic Array (NORSAR) , the Norwegian Regional Seismic Array (NORESS), the Arctic Regional Seismic Array (ARCESS) and the Spitsbergen Regional Array for the period 1 April - 30 September 1997. Statistics are also presented for additional seismic stations, which through cooperative agreements with institutions in the host countries provide continuous data to the NORSAR Data processing ... |
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| Development of a Lithospheric Model and Geophysical Data Base for North Africa |
20 OCT 97 |
85 pages |
| Authors:
D. I. Doser; G. R. Keller; S. Harder; K. C. Miller; P. J. Dial; TEXAS UNIV AT EL PASO DEPT OF GEOLOGICAL SCIENCES
|
| We have collected seismic, geologic gravity and other potential data to develop a model of North African lithosphere via an integrated approach. We have generated a Bouguer gravity map and modeled gravity data along 3 transects. Seismograms from Worldwide Standardized Seismograph Network Stations of magnitude greater than 4.9 earthquakes occurring within North Africa (1963-1988) have also been collected and digitized. The regional waveforms of these seismograms have been used to ... |
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| Investigation of Characteristics of Seismic Waves from the May 21, 1992 Lop Nor Nuclear Explosion Using IRIS Broadband Data |
06 OCT 97 |
28 pages |
| Authors:
Jiajun Zhang; CALIFORNIA UNIV SANTA CRUZ
|
| This is the final report for this grant to develop new seismological techniques for source characterization of nuclear explosions and earthquakes using broadband waveforms. Two studies are presented. The first study demonstrated that source parameters determined using routine methods are often biased due to unmodeled effects of the earth's structure. For the January 17, 1994 Northridge, California earthquake, we examined the results obtained using various techniques and concluded that a ... |
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| Calibration of Regional Wave Discriminants in Diverse Geological Environments: Topographic Correlations |
12 SEP 97 |
43 pages |
| Authors:
Thorne Lay; CALIFORNIA UNIV SANTA CRUZ EARTH SCIENCE BOARD
|
| This is the final report for this grant to explore waveguide effects on high frequency regional signals. Three studies are presented. The first is a theoretical investigation of the effects of thin crustal structure on Lg propagation. This study demonstrates that standard Lg in the frequency band 0.3 to 2 Hz does not develop in crustal structures less than 10 km thick due to a lack of overtone energy. This ... |
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| Earthquake Engineering Site Characterization - Proceedings of Research Needs Workshop |
SEP 97 |
319 pages |
| Authors:
Joseph P. Koester; Tina L. Holmes; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS GEOTECHNICAL LAB
|
| The Earthquake Engineering Site characterization - Research Needs Workshop was held at the U.S. Army Engineer Waterways Experiment Station (WES) 27 and 28 June 1995 to bring together technical specialists from WES, Corps of Engineers Districts, the U.S. Bureau of Reclamation (USER), and academia to solicit input for development of improved geophysical techniques for earthquake engineering site characterization. The ultimate goal of the work unit is to develop tools to ... |
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| Analysis of Soviet DSS Records for Propagation and Modeling of Lg Blockage across Major Crustal Features |
04 APR 97 |
46 pages |
| Authors:
Scott B. Smithson; James C. Schatzman; WYOMING UNIV LARAMIE DEPT OF GEOLOGY
|
| To develop our model, we analyze the data obtained using 42 chemical explosions along the profile. Applying a travel-time tomographic inversion method, we developed a velocity model and estimates of its resolution. Two important resolved features of the model are: 1) high velocity block at the base of the crust under the Baltic Shield, 2) crustal roots under the Ural Mountains. Using the data from 3 nuclear explosions in the ... |
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| UGT Ground Shock Data and Effects Technology Transfer. Phase 1- Feasibility Study |
APR 97 |
85 pages |
| Authors:
Danny N. Burgess; Gary L. Wintergerst; DEPARTMENT OF ENERGY LAS VEGAS NV NEVADA OPERATIONS OFFICE
|
| This effort was a brief feasibility study directed toward determining whether ground motion and structural response data developed at the Nevada Test Site during the Defense Nuclear Agency underground nuclear test (UGT) program might be useful to the earthquake engineering community. Response spectra were computed for ground motions from four UGT events. They were compared with response spectra from selected records from the Northridge Earthquake and with predicted spectra for ... |
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| The Physical Basis for the Lg/P Discriminant: General Properties and Preliminary Modeling |
MAR 1997 |
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| Authors:
Theron J. Bennett; Keith L. McLaughlin; Margaret E. Marshall; Jeffry L. Stevens; MAXWELL TECHNOLOGIES INC SAN DIEGO CA
|
| A critical problem for reliable implementation of regional discrimination is incomplete understanding of how regional seismic signals depend on physical characteristics of the source and propagation path to the recording station. This research is directed at improving understanding of effects of these characteristics on an important regional discriminant, the Lg/P ratio. An empirical element in this research program has aimed at describing behavior of Lg/P ratios and their dependence on ... |
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| Analysis of Digital Teleseismic Array Data Collected in South Central Siberia and Northern Mongolia, GSN SKS Waves and S Waves from Lop Nor Nuclear Explosions |
27 FEB 97 |
74 pages |
| Authors:
Paul M. Davis; Shangxing Gao; Laura Borton; CALIFORNIA UNIV LOS ANGELES DEPT OF EARTH AND SPACE SCIENCES
|
| The objective of this research is to provide information on seismic wave propagation in areas of large scale heterogeneity. Data collected in south central Siberia and northern Mongolia have been analyzed along with digital data from the Global Seismic Network in order to identify effects on the propagation caused by large scale heterogeneity in the mantle. These effects need to be taken into account when using seismic arrays to monitor ... |
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| Eurasian Surface Wave Phenomenology and Inversion for Crustal and Upper Mantle Structures |
10 FEB 97 |
90 pages |
| Authors:
Anatoli Levshin; Michael H. Ritzwoller; COLORADO UNIV AT BOULDER DEPT OF PHYSICS
|
| Earthquake seismograms recorded by several global and regional networks between 1988 and late-1995 were used to measure the group velocity dispersion of fundamental Rayleigh and Love waves crossing Eurasia. More than 9, 000 three-component long period seismograms following more than 600 events with Ms greater than 4.5 were processed. This data set was reduced by clustering' observations along similar paths into measurements along the unique path,' and rejecting outliers. The ... |
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| Laboratory Studies of Pore Pressure, Attenuation, Anisotropy and Inhomogeneities in the Oceanic Crust |
97 |
5 pages |
| Authors:
Nikolas I. Christensen; PURDUE UNIV LAFAYETTE IN
|
| The purpose of this project was to study the composition, genesis and evolution of oceanic crustal rocks by investigating the relationships between mineralogy, porosity, seismic velocity and seismic attenuation. These properties are dependent on the processes which form the oceanic crust and change as the crust evolves. |
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| Evolution of Fracture Networks in the Upper Oceanic Crust |
97 |
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| Authors:
Geoffrey Thompson; Kathryn M. Gillis; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| The long term objective of this project was to establish realistic geologic constraints on the variables which contribute to the seismic signal in the upper oceanic crust, and to determine how these variables evolve with age. To begin to address this problem, our short term objective was to characterize the nature of porosity in a section of oceanic crust exposed in the Troodos Ophiolite, Cyprus. By comparing the distribution of ... |
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| An Integrated Study of Lithospheric Structure, Regional Seismic Wave Propagation, and Seismic Discrimination Capability in the Middle East |
07 OCT 96 |
127 pages |
| Authors:
Keith Priestley; CAMBRIDGE UNIV (UNITED KINGDOM) DEPT OF EARTH SCIENCES
|
| The upper mantle compressional wave velocity beneath the Iranian Plateau is determined by measuring two station interval velocities from first arrivals in the distance range 2 to 18 degrees reported in the ISC. The Pn velocity is near 8.1 km/s beneath the Zagros Mts. and most of the northern part of the plateau. A lower Pn velocity of about 7.8 km/s occur beneath NW Iran. Additional Pn velocity estimates are ... |
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| Final Technical Report on Contract N00014-93-1-0068 (Pacific Geoscience Centre) |
07 DEC 95 |
7 pages |
| Authors:
Kristin Rohr; GEOLOGICAL SURVEY OF CANADA SIDNEY (BRITISH COLUMBIA) PACIFIC GEOSCIENCE CEN TRE
|
| Summary of analysis and interpretation of data funded by this grant. (AN) |
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| Seismic Studies of the Caspian Basin and Surrounding Regions |
14 NOV 95 |
85 pages |
| Authors:
Keith Priestley; Stephen Mangino; CAMBRIDGE UNIV (UNITED KINGDOM)
|
| In order to investigate the anomalous crust and upper mantle structure of the south Caspian Basin, we installed a network of six three component seismograph stations within the countries of Turkmenistan and Azerbaijan. Improved knowledge of the crust and upper mantle structure of the south Caspian Basin is important in a seismic verification context because of the anomalous effect it has on regional seismic waveforms. Our objective is to determine ... |
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| Proceedings of the Annual Seismic Research Symposium on Monitoring a Comprehensive Test Ban Treaty (17th) Held in Scottsdale, Arizona on 12-15 September, 1995 |
14 AUG 95 |
1071 pages |
| Authors:
James F. Lewkowicz; Jeanne M. McPhetres; Delaine T. Reiter; PHILLIPS LAB HANSCOM AFB MA
|
| Limitation Code: APPROVED FOR PUBLIC RELEASE DOCUMENT PARTIALLY ILLEGIBLE |
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| Stability of the P to S Energy Ratio in the Diffusive Regime, |
14 AUG 1995 |
10 pages |
| Authors:
George C. Papanicolaou; Leonid V. Ryzhik; Joseph B. Keller; STANFORD UNIV CA DEPT OF MATHEMATICS
|
| In the presence of inhomogeneities the propagation of elastic wave energy can be modeled by radiative transport equations. This is a good approximation when typical wavelengths are short compared to the overall propagation distance, correlation lengths are comparable to wavelengths so that the inhomogeneities have appreciable effect and the fluctuations are weak. The relevant transport equations are derived in starting from the elastic wave equations in an unbounded medium. |
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| Effects of Explosion Depth and Crustal Heterogeneity of Lg Waves, |
14 AUG 1995 |
8 pages |
| Authors:
H. Keers; K. Vogfjoerd; G. Nolet; F. A. Dahlen; PRINCETON UNIV NJ DEPT OF GEOLOGICAL AND GEOPHYSICAL SCIENCES
|
| We use ray theory to model the propagation of Lg waves through 2D and 3D layered crustal models. The layers are homogeneous, and the discontinuities are undulating. The Lg wave train is modelled by multiple S reflections within the crustal layers. The ray tracing system is reduced from a set of linear differential equations to a set of maps. If the medium has three or more discontinuities the number of ... |
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| Statistical Frameworks for Seismic Discrimination, |
14 AUG 1995 |
9 pages |
| Authors:
D. N. Anderson; K. K. Anderson; D. N. Hagedorn; S. R. Sain; C. J. Young; BATTELLE PACIFIC NORTHWEST LABS RICHLAND WA
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| To verify compliance with a Comprehensive Test Ban Treaty (CTBT), low energy seismic activity must be detected and discriminated. Monitoring small-scale seismic activity will require regional monitoring capabilities (within approximately 2000 km, U.S. Congress (1988)). The reliable discrimination of small-scale seismic events requires a multi-dimensional representation of the seismic signal. A multi-dimensional characterization might include wave arrival times, magnitudes, and incidence and azimuth angles. These measurements can be used singly ... |
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| Development of Regional Discriminants, |
14 AUG 1995 |
10 pages |
| Authors:
Don V. Helmberger; Xi Song; CALIFORNIA INST OF TECH PASADENA SEISMOLOGICAL LAB
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| With the installation of broadband, high dynamic range instruments, it has become possible to compare the regional waveforms of earthquakes and explosions at magnitudes 3 to 6. These waveforms are similar for event sequences in many situations and can be inverted for source mechanisms. We find that flat-layered models are sufficient for inverting seismograms at periods greater than a few seconds. This paper presents three studies aimed at determining crustal ... |
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| Constraints on the Upper Mantle Velocity Beneath the Yellow Sea, Eastern China, |
14 AUG 1995 |
8 pages |
| Authors:
John J. Cipar; PHILLIPS LAB HANSCOM AFB MA
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| Detailed models of the crust and upper mantle are crucial for precise event location and computation of realistic synthetic seismograms for earthquake/explosion identification. However, such models are not available for most of the globe, including eastern China. In this report, data from the 1992 Yellow Sea earthquake is used to put constraints on the upper mantle velocity beneath the Yellow Sea and eastern China. The average velocity in the upper ... |
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SEISMIC VELOCITY
