| An Analysis of the Seismic Source Characteristics of Explosions in Low-Coupling Dry Porous Media |
30-Sep-2009 |
11 pages |
| Authors:
John R Murphy; Brian W Barker; SCIENCE APPLICATIONS INTERNATIONAL CORP SAN DIEGO CA
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 | The dependence of seismic source coupling of underground nuclear explosions on the characteristics of the Q explosion source medium is an important consideration in any assessment of nuclear test monitoring capability. In particular, while experience has indicated that normal depth explosions in almost all hardrock and water saturated emplacement media (i.e., good-coupling media) are roughly consistent with a single nib/yield relation for any fixed tectonic source region, explosions in dry, ... |
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| Regionalization of Crustal and Upper Mantle Q Structure in Eastern Eurasia Using Multiple Regional Waves |
05 FEB 2007 |
62 pages |
| Authors:
James Gaherty; Arthur Lerner-Lam; COLUMBIA UNIV PALISADES NY LAMONT-DOHERTY EARTH OBSERVATORY
|
| We have mapped lateral variations in seismic Q in eastern Eurasia, including continental China, central Asia, Mongolia and Siberia, using high-frequency regional phases Lg and Pn, as well as long-period Rayleigh waves. We measured Q of crustal Lg waves in eastern Eurasia using two-station methods. Over 5,000 spectral ratios from 594 interstation paths were used to estimate Lg Q Omicron and Eta(Q at1 Hz and its frequency dependence). These path ... |
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| Continent-Wide Maps of Lg Coda Q Variation and Rayleigh-wave Attenuation Variation for Eurasia |
30 JAN 2007 |
50 pages |
| Authors:
Brian J. Mitchell; Lianli Cong; SAINT LOUIS UNIV MO
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| We present new maps of Lg coda Q and its frequency dependence at 1 Hz (Qo and eta, respectively) as well as Rayleigh-wave attenuation coefficients at 5, 10, 20 and 50 s across virtually all of Eurasia. Qo is relatively high, 700 or more, in most cratonic regons but is surprisingly low in the Arabian craton (300-450), the Siberian trap portion of the Siberian Platform (~450) and the Deccan trap ... |
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| Report on the International Workshop River Deltas: Evolution, Environmental, Challenges and Sustainable Management |
SEP 2006 |
10 pages |
| Authors:
CORPS OF ENGINEERS WASHINGTON DC
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| "The most important landform produced where a river enters a body of standing water is known as a delta. The term is normally applied to a depositional plain formed by a river at its mouth, with the implication that sediment accumulation at this position results in an irregular progradation of the shoreline. Their evolution and shapes are depending on (1) characteristics within the drainage basin that provides the sediment (climate, ... |
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| Amplitude Analysis and Modeling of Regional Phases in PNE Profiles in Northern Eurasia and Seismic Regionalization |
30 JUN 2006 |
150 pages |
| Authors:
Igor B. Morozov; Hongyan Li; Elena Morozova; Joel Duenow; Haishan Zheng; Scott B. Smithson; WYOMING UNIV LARAMIE DEPT OF GEOLOGY
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| Seismological observations play an important role in detecting and locating all nuclear events, determining their yields and distinguishing them from earthquakes and other chemical explosions. Regional phases play a critical role for small-yield nuclear test monitoring. Regional phases travel in the crust and the upper mantle, which are very heterogeneous, therefore, calibration of phase propagation characteristics within different tectonic and geologic environments is necessary to use regional phases for nuclear ... |
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| The Influence of Ridge Geometry at the Ultraslow-Spreading Southwest Indiean Ridge (9 deg - 25 deg E): Basalt Composition Sensitivity to Variations in Source and Process |
FEB 2006 |
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| Authors:
Jared J. Standish; MASSACHUSETTS INST OF TECH CAMBRIDGE JOINT PROGRAM IN APPLIED OCEAN SCIENCE AND ENGINEERING
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 | Between 9 deg - 25 deg E on the ultraslow-spreading Southwest Indian Ridge lie two sharply contrasting supersegments. One 630 km long supersegment erupts N-MORB that is progressively enriched in incompatible element concentrations from east to west. The second 400 km long supersegment contains three separate volcanic centers erupting E-MORB and connected by long amagmatic accretionary segments, where mantle is emplaced directly to the seafloor with only scattered N-MORB and ... |
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| Slip on Ridge Transform Faults: Insights From Earthquakes and Laboratory Experiments |
JUN 2005 |
125 pages |
| Authors:
Margaret S. Boettcher; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| The relatively simple tectonic environment of mid-ocean ridge transform fault (RTF) seismicity provides a unique opportunity for investigation of earthquake and faulting processes. We develop a scaling model that is complete in that all the seismic parameters are related to the RTF tectonic parameters. Laboratory work on the frictional stability of olivine aggregates shows that the depth extent of oceanic faulting is thermally controlled and limited by the 600C isotherm. ... |
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| Tsunami Disaster Mitigation Research in the United States |
JAN 2005 |
15 pages |
| Authors:
Michael J. Briggs; Jose C. Borrero; Costas E. Synolakis; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
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| This paper presents an update of the Corps of Engineers tsunami disaster mitigation research in the United States. Because the U.S. has not had any major tsunami disasters in many years, the Corps does not have a formal mission or policy for incorporating tsunami runup considerations in the design wave height for coastal structures. In the 1990's the Corps Coastal and Hydraulics Laboratory did participate in substantial physical modeling of ... |
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| Improved Focal Depth Determination for Use in Seismic Monitoring of the Underground Nuclear Explosions |
19 NOV 2003 |
60 pages |
| Authors:
J. R. Murphy; B. W. Barker; M. E. Marshall; W. L. Rodi; SCIENCE APPLICATIONS INTERNATIONAL CORPSAN DIEGO CA
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| Seismic event location remains as one of the most important discriminants for separating natural tectonic and explosive events. For example, it has been estimated that approximately 8O%of known global earthquakes have focal depths greater than 50 km or are located more than 25 km at sea. Since underwater nuclear explosions can be confidently identified to very low yields using hydroacoustic data, it follows that the vast majority of earthquakes can ... |
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| Kinematic and Dynamic Studies of the Coso Geothermal and Surrounding Areas |
12 SEP 2003 |
99 pages |
| Authors:
Jonathan C. Lewis; Christopher J. Pluhar; MASSACHUSETTS UNIV AMHERST DEPT OF GEOLOGY
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| During the final stages of this project we encountered some delays in securing a no-cost extension that was requested in order to complete additional analyses that were not originally anticipated. These analyses include one additional radiometric age and geochemical analyses of lava flow units. This Final Technical Report serves to convey the results of the efforts of Tasks 1,2, 3 and 4 (Table 1.1). Because Task 4 represents Integration and ... |
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| Discrimination, Detection, Depth, Location, and Wave Propagation Studies Using Intermediate Period Surface Waves in the Middles East, Central Asia, and the Far East |
JUL 2003 |
152 pages |
| Authors:
Anatoli L. Levshin; Michael H. Ritzwoller; COLORADO UNIV AT BOULDER DEPT OF PHYSICS
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| The objective of this research was to construct surface wave group velocity maps at intermediate periods for the Near East, Central Asia and the Far East and to estimate the possibility of using these maps to extract weak surface wave signals and measure their amplitude spectra. To reach these goals we acquired broadband digital records of more than 1600 events that occurred in and around Eurasia during the period 1976-1998 ... |
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| Electronic Sensors for Microfluidics |
JUN 2003 |
54 pages |
| Authors:
Lydia L. Sohn; PRINCETON UNIV NJ DEPT OF PHYSICS
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| The goal of this ARO/DARPA funded project is to develop a fully integrated microfluidic device that would be capable of electronically detecting specific bacterial pathogens in whole blood, and other fluids such as sputum and urine. The integrated device consists of two sensors: a microscale Coulter counter that sizeds and then fractionates blood samples based on particulate size; and an on-chip high frequency spectrometer that interrogates the dielectric response of ... |
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| Field Evaluation of Sediment Structure and Content Relative to Associated Hydrates |
21 JAN 2003 |
16 pages |
| Authors:
Richard B. Coffin; NAVAL RESEARCH LAB WASHINGTON DC
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| The goal of the first year in the program is to initiate sample analysis of hydrates and sediments to provide a database that will contribute to the development of a hydrate dissociation simulator. This work was conducted primarily on samples previously taken in the Cascadia Margin (CM) and Gulf of Mexico (GOM). In addition there is some comparison with data from samples taken in 1998 on the Haakon-Mosby Mud Volcano ... |
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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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| Renovating U.S. Strategic Arms Control Policy. Strategic Forum, Number 178, February 2001 |
FEB 2001 |
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| Authors:
Richard Sokolsky; NATIONAL DEFENSE UNIV WASHINGTON DC INST FOR NATIONAL STRATEGIC STUDIES
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| There has been a tectonic shift in the strategic landscape since the Strategic Arms Reduction Treaty (START) negotiations concluded in the early 1990s. The Soviet Union and the Warsaw Pact are defunct. America and Russia are no longer enemies and the nuclear arms race between the two countries, for all intents and purposes, over. The threat of a surprise nuclear attack has all but vanished along with any plausible scenario ... |
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| Rockburst Research Applied to Nuclear Event Discrimination |
30 SEP 1999 |
92 pages |
| Authors:
Holly Hoffman; Misty Cook; Hana Baker; Marvin Speece; Bill Sill; MONTANA TECH OF THE UNIV OF MONTANA BUTTE
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| Rockbursts produce seismic signals that are similar to those associated with near surface earthquakes and explosions. Some of the methods developed for source mechanism studies also encompass imaging techniques appropriate for nuclear event verification, and, as a result, have implications for the Comprehensive Test Ban Treaty (CTBT). Past experiments have demonstrated a clear relationship between Barkhausen Noise (BN) and stress in pipeline steel samples. Stress ... |
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| Intraplate Earthquakes and State of Stress in the former Soviet Union |
24 AUG 1998 |
31 pages |
| Authors:
Lynn R. Sykes; Sergey Yunga; Tatiana Rautian; COLUMBIA UNIV NEW YORK
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| Information on intraplate earthquakes in the Former Soviet Union and adjacent regions is collected from historical and instrumental records. Since most of the territory of the Russian Republic is intraplate in its tectonic character, intraplate earthquakes and the stresses that generate them are of importance to the monitoring of the Comprehensive Test Ban Treaty (CTBT). Data from a number of catalogs are merged so as to study locations and sizes ... |
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| Knowledge-Based Visualization of Multidisciplinary Databases for IDC interactive Analysis: Region Specific and Global |
15 JUL 1998 |
46 pages |
| Authors:
Muawia Barazangi; David Steer; CORNELL UNIV ITHACA NY INST FOR THE STUDY OF THE CONTINENTS
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| A prototype Geographical Information System (GIS) with global coverage was developed at Cornell University in order to assist the Prototype International Data Center (PIDC) in merging the results of the four monitoring technologies (seismic, hydroacoustic, infrasound, and radionuclide) and to assist in ongoing calibration and location studies during the implementation of the Comprehensive Test Ban Treaty (CTBT). This system is intended to expand the ... |
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| Seafloor Geomorphology, Gas and Fluid flow, and slope Failure on the Southern Cascadia Continental Margin |
30 JUN 1998 |
12 pages |
| Authors:
Daniel L. Orange; MONTEREY BAY AQUARIUM RESEARCH INST PACIFIC GROVE CA
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| The objective of this project is to evaluate the role of fluid flow, overpressuring, and gas migration in the creation and moderation of submarine geomorphology. This project addresses questions about: 1) the lateral and vertical extent of detectable overpressued fluids and gas in the subsurface, 2) gas-related structures and manifestations of flow on the surface, 3) seafloor geomorphology related to gas and fluid expulsion, and 4) structural controls on gas ... |
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| Seismic Characterization Using the Belbasi Array |
JUN 1998 |
32 pages |
| Authors:
Sadi Kuleli; KANDILLI OBSERVATORY AND EARTHQUAKE RESEARCH INST ISTANBUL (TURKEY)
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| This report results from a contract tasking Kandilli Observatory and Earthquake Research Institute as follows: The contractor will characterize the seismic structure and behavior of the Anatolian region using data from the Belbasi and Keskin arrays near Ankara, Turkey. The research will include studies to understand the amplitude and phase behavior of seismic signals received at Belbasi and other regional stations operated by KOERI. It will ... |
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| Seismic Hazards of the Upper Mississippi Embayment |
JAN 1998 |
132 pages |
| Authors:
Roy Van Arsdale; MEMPHIS UNIV TN
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| Earthquakes are a major hazard in the middle Mississippi River valley of the upper Mississippi embayment. Microseismicity along the New Madrid seismic zone is illuminating faults that are believed responsible for the great New Madrid earthquakes of 1811-1812. These faults are right lateral strike slip faults within the Blytheville arch and western margin of the Reelfoot rift that are linked by the southwest dipping Reelfoot reverse fault. The Bootheel lineament ... |
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| Propagation of Regional Phases and Their Codas in Southern Asia and the Middle East |
17 NOV 1997 |
64 pages |
| Authors:
Lianli Cong; Brian J. Mitchell; SAINT LOUIS UNIV MO DEPT OF EARTH AND ATMOSPHERIC SCIENCES
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| Observed velocities and attenuation of fundamental-mode Rayleigh waves in the period range 7-82 sec were inverted for shear-wave velocity and shear-wave Q structure in the Middle East using a two-station method. Additional information on Q structure variation within each region was obtained by studying amplitude spectra of fundamental-mode and higher-mode Rayleigh waves. We obtained models for the Turkish and Iranian Plateaus (Region 1), areas surrounding and including the Black and ... |
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| Interaction of Regional and Teleseismic Waves with 3-D Earth Structure |
16 APR 97 |
83 pages |
| Authors:
Brian L. Kennett; AUSTRALIAN NATIONAL UNIV CANBERRA RESEARCH SCHOOL OF EARTH SCIENCES
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| This report describes a range of studies which have been directed at improved delineation of structure at regional scales which can be used in calibrating seismic information from regional or teleseismic sources. The first two sections describe the development of fine-scale three- dimensional models for the crust and lithosphere incorporating a broad class of seismic information and the extension of such procedures to include anisotropy. The next part develops a ... |
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| A Qualitative and Quantitative Study of the Distribution of Pelagic Sediment in the Atlantic Basin |
FEB 97 |
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| Authors:
Helen F. Webb; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| By numerically modeling pelagic sedimentation as a diffusive process, we study sedimentation effects in terms of stochastic parameters including seafloor RMS height, abyssal hill spacing, and slope distribution. Understanding gained allows the construction of inverse problems to obtain information about sediment distribution and basement morphology from multibeam bathymetric data. Using maximum likelihood estimation to compare slope distribution functions calculated from data to those from filtered model topographies, we estimate average ... |
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| Fine-Scale Record of Faulting in ONR Natural Laboratories |
15 JAN 97 |
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| Authors:
Brian E. Tucholke; Gary E. Jaroslow; W. K. Stewart; Martin C. Kleinrock; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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| We analyzed fault patterns in ocean crust on the west flank of the Mid-Atlantic Ridge at 25 deg 25' - 27 deg 10'N, 45 deg 00' - 49 deg 00'W, using HMR1 long-range sidescan-sonar data and multibeam bathymetry. Our studies show that brittle strain on normal faults varies with respect to intrasegment tectonic setting and with respect to variation in magma input at the rift axis. Our analyses clearly document ... |
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| Implications of Fine-Scale Magnetics for the Structure and Evolution of Slowly Accreted Oceanic Crust |
02 JAN 97 |
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| Authors:
Maurice A. Tivey; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF GEOLOGY AND GEOPHYSICS
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| The long range objective of this program is to understand the structure of oceanic crust created at slow-spreading ridges by investigating the patterns of magnetization that reside in the crust. The project seeks to investigate how crustal magnetic fields are related to the structural deformation history of oceanic crust formed in slow spreading environments and how magnetization may be used to predict the properties of the underlying crust. Scientific Objectives ... |
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| The Geological Record of Oceanic Crustal Accretion and Tectonism at Slow-Spreading Ridges |
DEC 96 |
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| Authors:
Gary E. Jaroslow; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| Studies of the morphology of slow-spreading ridges have contributed enormously to our understanding of the generation of oceanic crust. However, such work has largely been confined to the ridge axis, and therefore is limited in its application. The objective of this Thesis was to interpret the structural development of slow-spreading ridge segments by: (1) delineating the nature, magnitude, and relative importance of primary tectonic and volcanic processes that control crustal ... |
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| Source Functions of Nuclear Explosions from Spectral Synthesis and Inversion |
20 NOV 96 |
32 pages |
| Authors:
Peter Puster; Thomas H. Jordan; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
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| We apply methods for the recovery of the frequency dependent moment rate tensor, M(w), to the study of Lop Nor nuclear explosions. This approach encompasses many source parameter diagnostics that have been traditionally used to discriminate nuclear explosions from chemical explosions and earthquakes and has the potential to provide new discrimination tools. We parameterize the source as M(w) = M1(a)) + MD(a)), where M1(co) and MD((O) are isotropic and deviatoric ... |
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| Nonlinear Analysis of Seafloor Topography |
19 NOV 96 |
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| Authors:
Sarah A. Little; Deborah K. Smith; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF GEOLOGY AND GEOPHYSICS
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| Large- and small-scale tectonism and volcanism shape seafloor topography near Mid-Ocean Ridges (MOR) and produce a variety of both regular and irregular morphological features. Large consistent features such as the Mid- Atlantic Ridge (MAR), central valley, and crestal mountains, are superimposed by smaller and more irregular features such as ridge offsets, ridge-parallel faults, and volcanic constructions. Many of these features are observable on Sea Beam swath-collected bathymetry. Our long-term objective ... |
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| The Off-Axis Volcanic Record in the ONR Atlantic Natural Laboratory |
05 NOV 96 |
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| Authors:
Deborah K. Smith; B. E. Tucholke; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF GEOLOGY AND GEOPHYSICS
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| Our long range scientific objective is to understand the operation and distribution of processes that control construction and degradation of volcanic adifices on the seafloor. Submarine volcanoes (seamounts) significantly contribute or even dominate roughness characteristics of the seafloor in many parts of the world's oceans. Despite this fact their fundamental distributions and the controls on their distributions remain poorly understood. To begin to address this problem, our short term objective ... |
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| Slope Failure, Tectonics, and Gas and Fluid Expulsion on the Southern Cascadia Continental Shelf and Slope: Effects on Seafloor Geomorphology |
14 OCT 96 |
7 pages |
| Authors:
Daniel L. Orange; MONTEREY BAY AQUARIUM RESEARCH INST PACIFIC GROVE CA
|
| The objective of this project is to evaluate the role of fluid flow, overpressuring, and gas migration in the creation of failure features on the seafloor of a tectonically active continental margin. This project addresses questions about the lateral and vertical extent of detectable gas and gas- related structures in the subsurface, the regional distribution of failure features, the locations of overpressured fluids in the subsurface, and how the structural ... |
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| Ridge Segmentation, Tectonic Evolution and Rheology of Slow-Spreading Oceanic Crust |
SEP 96 |
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| Authors:
Javier E. Guiral; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| Slow spreading ridges are composed of ridge segments, which are fundamental units of magmatic accretion and tectonic deformation. The objective of this thesis is to characterize these tectonic processes, identify factors controlling segment propagation, and constrain lithospheric strength with deformation experiments. In chapter 2, bathymetry and gravity analyses show that here is a marked asymmetry in bathymetry and gravity near segment offsets. A model of faulting explains these observations suggests ... |
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| High Resolution Intermediate Period (10-40 s) Group Velocity Variations Across Central Asia |
10 AUG 96 |
22 pages |
| Authors:
Anatoli L. Levshin; Michael H. Ritzwoller; COLORADO UNIV AT BOULDER DEPT OF PHYSICS
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| This research is dedicated to investigating the relevance and use of intermediate period (10 - 40 s) surface wave data in problems of detection, discrimination, and the accurate location of small events using regional array data. It is focused on the analysis of data from events throughout Central and Southern Asia within 27 degrees of the Kyrgyz Telemetered Seismic Network. The main efforts during the 1 year time period covered ... |
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| Digital Database Development and Seismic Characterization and Calibration for the Middle East and North Africa |
31 JUL 96 |
81 pages |
| Authors:
Muawia Barazangi; Dogan Seber; Eric Sandvol; Marisa Vallve; CORNELL UNIV ITHACA NY INST FOR THE STUDY OF THE CONTINENTS
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| It is essential for the CTBT monitoring efforts that multidisciplinary information on any given region is readily available and accessible in a digital, on-line format via electronic networks for use by concerned researchers and decision makers. Our objective is to collect and organize all available seismological, geophysical, and geological data sets for the Middle East and North Africa into a comprehensive Geographic Information System (GIS). In addition, we are producing ... |
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| Uppermost Mantle Structure in Southern Eurasia from PN Tomography and Sn Attenuation |
JUN 96 |
60 pages |
| Authors:
Thomas M. Hearn; James F. Ni; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| This project has investigated the seismic characteristics of southern Eurasia through Pn travel time tomography and the regional mapping of attenuation for high frequency Sn and Lg waves. Pn tomography results indicate that much of the uppermost mantle beneath southern Eurasia has low P-wave velocity and a small amount of melt. Mapping of Sn propagation efficiency confirms that regions with low Pn velocity generally do not propagate Sn waves efficiently. ... |
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| Wave Propagation and Source Parameters in Eurasia |
12 FEB 96 |
85 pages |
| Authors:
Charles A. Langston; Daejin Kang; Mingguang Wang; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF GEOSCIENCES
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| Regional seismograms from the Soviet JVE explosion were modeled. The explosion part of the source contained considerable RDP overshoot with possible spall contribution. The tectonic release part was composed of stress relaxation and secondary high frequency sources. Pn, Sn, Rayleigh and Love waves were modeled. SsPmp phases were discovered in regional waves and modeled using ray theory and synthetic seismogram computations. SsPmp is an important wave in broadband data for ... |
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| Seismoacoustic Studies of the Norwegian Sea, |
14 AUG 1995 |
6 pages |
| Authors:
Donna K. Blackman; John A. Orcutt; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA INST OF GEOPHYSICS AND PLANET ARY PHYSICS
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| The U.S. Navy hydrophone arrays (SOSUS) record seismoacoustic events in a range of frequencies which includes earthquake and explosive sources as well as those relevant to submarine detection, for which they were designed. In the Norwegian Sea we compare detection of seismoacoustic events on SOSUS with seismic detection by the arrays on land in Norway. We also study seismic activity along the spreading centers between Iceland and Svalbard in an ... |
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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
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| 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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| The Physical Basis for the Lg/P Discriminant, |
14 AUG 1995 |
1 pages |
| Authors:
T. J. Bennett; K. L. McLaughlin; S-CUBED RESTON VA
|
| Recent interest in a Comprehensive Test Ban Treaty (CTBT) has stimulated a desire to detect and identify much smaller seismic events. Furthermore, concern for possible proliferation of nuclear weapons into countries where nuclear weapons testing was not previously at issue requires extending seismic capabilities into new geographic regions. To reach these goals at magnitude levels of interest will require utilization of regional seismic signals. Unfortunately, implementation of effective regional discriminants ... |
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| Transportability of Regional Phase Spectral Ratio Discriminants, |
14 AUG 1995 |
1 pages |
| Authors:
T. J. Bennett; J. R. Murphy; S-CUBED RESTON VA
|
| This research program is intended to provide a thorough assessment of the transportability of regional phase spectral ratios as discriminants between underground nuclear explosions and other source types. Although Lg spectral ratios appeared to offer considerable promise for distinguishing between nuclear explosions and nearby earthquakes based on experience from the vicinity of the Nevada Test Site, attempts to extend this spectral ratio discriminant into other geographic regions (e.g. the vicinity ... |
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| Application of Soviet PNE Data to the Assessment of the Transportability of Regional Discriminants, |
14 AUG 1995 |
1 pages |
| Authors:
J. R. Murphy; I. O. Kitov; B. W. Barker; D. D. Suitanov; MAXWELL LABS INC LA JOLLA CA S-CUBED DIV
|
| In order to discriminate the regional seismic signals produced by underground nuclear explosions from those produced by earthquakes, rockbursts and conventional mining explosions of comparable magnitude, it is necessary to know the range of nuclear explosion signal variation that can be expected as a function of source and propagation path conditions over the entire ranges of these conditions which may be encountered in global test monitoring. However, most research conducted ... |
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| Regional Wave Attenuation and the Lg/P Discriminant, |
14 AUG 1995 |
11 pages |
| Authors:
Thomas J. Sereno Jr.; Darrin D. Wahl; Richard D. Jenkins; Donna J. Williams; SCIENCE APPLICATIONS INTERNATIONAL CORP SAN DIEGO CA
|
| Results from previous empirical studies indicate that the high-frequency Lg/P ratio is one of the most promising discriminants at regional distances. However, many of these studies are based on co-located earthquakes and explosions in limited geographic regions, and their results must be recalibrated for each new source region. We just started a two-year research project to develop frequency-dependent attenuation models for regional phases and to use them to generalize the ... |
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| Surface Wave Group Velocity Measurements Across Eurasia, |
14 AUG 1995 |
11 pages |
| Authors:
A. L. Levshin; M. H. Ritzwoller; L. I. Ratnikova; COLORADO UNIV AT BOULDER DEPT OF PHYSICS
|
| Earthquake and nuclear explosion data recorded by the GSN, GEOSCOPE, CDSN, and MEDNET broadband networks and the IRIS/Kyrghyz regional network (KNET) during 1988-1995 have been used to study the characteristics of surface wave propagation across Eurasia. More than 3500 three-component records for different epicenter - station pairs have been processed. Group and phase velocity dispersion curves, spectral amplitude curves, as well as frequency - dependent azimuthal particle - motion anomalies ... |
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| Regional Wave Propagation in and around the Tibetan Plateau, |
14 AUG 1995 |
10 pages |
| Authors:
T. J. Owens; H. P. Crotwell; D. E. McNamara; G. E. Randall; SOUTH CAROLINA UNIV COLUMBIA
|
| The Tibetan Plateau is a dominant structural feature influencing seismic wave propagation in Central Asia. Using data from the 1991-92 Tibetan Plateau Seismic Experiment deployment of broadband PASSCAL sensors, we are studying the effects of the Tibetan Plateau on a variety of regional phases propagating within the plateau and crossing its boundaries. In this report, we summarize results from two such studies. First, the propagation and attenuation characteristics of Lg ... |
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| Stochastic Modeling of Small-Scale, Anisotropic Structures in the Continental Upper Mantle, |
14 AUG 1995 |
12 pages |
| Authors:
Thomas H. Jordan; James B. Gaherty; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| New methods for the analysis of three-component seismograms have been applied to data from both continental and oceanic regions. Polarization anisotropy, manifested as the splitting of surface, guided, and shear body waves, has been observed in all regions, but no significant azimuthal anisotropy has been detected. This is expected if the local orientation of olivine crystals in the upper mantle is incoherent on the scale of the path lengths used ... |
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| The Influence of 3-D Structure on Seismic Wave Propagation at Regional and Teleseismic Distances, |
14 AUG 1995 |
7 pages |
| Authors:
B. L. Kennett; AUSTRALIAN NATIONAL UNIV CANBERRA RESEARCH SCHOOL OF EARTH SCIENCES
|
| Three-dimensional heterogeneity is pervasive in the Earth on a wide variety of scales. The aim of this project is to improve understanding of the influence of lateral variations in structure in the upper mantle on wave propagation at regional to far-regional and teleseismic distances. At regional scales we have investigated how to map the seismic velocity structure of a region exploiting records from natural events as a model for upgrading ... |
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| The Effects of Anisotropy on Regional Seismic Wave Propagation, |
14 AUG 1995 |
10 pages |
| Authors:
Jeffrey Park; Liqiang Su; Jonathan Lilly; YALE UNIV NEW HAVEN CT DEPT OF GEOLOGY AND GEOPHYSICS
|
| We have examined the effect of seismic anisotropy on the scattering of surface waves in actively-deforming continental regions, many of which occur in areas of nonproliferation concern. We have approached the problem from three angles, (1) we have developed waveform inversion methods for Love-Rayleigh coupling in seismic data from the Tibetan Plateau and Tien Shan region, (2) we have developed a flat-layered surface wave code to study the effect of ... |
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| Seismic Characteristics and Mechanisms of Rockbursts, |
14 AUG 1995 |
10 pages |
| Authors:
T. J. Bennett; M. E. Marshall; K. L. McLaughlin; B. W. Barker; J. R. Murphy; S-CUBED RESTON VA
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| Rockbursts and related mining-induced seismicity present several interesting problems for seismic monitoring of potential underground nuclear explosion tests. Such events occur in mining areas throughout the world and may be quite frequent at levels currently of interest for CTBT. The shallow focal depths of rockbursts prevent their discrimination from nuclear tests on the basis of depth identification. Many rockbursts also appear to be inefficient in excitation of long-period surface waves ... |
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| Seismic Sources and Structure in Iran and the Caucasus from Joint Seismic Program Array Data, |
14 AUG 1995 |
7 pages |
| Authors:
G. A. Abers; W. Y. Kim; A. Lerner-Lam; KANSAS UNIV LAWRENCE DEPT OF GEOLOGY
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| Amplitudes of seismic waves recorded at the Caucasus network, along the north flanks of the Greater Caucasus, are measured and analyzed for attenuation characteristics. From one year of observation, 96 events between 1 and 10 from the network provide stable measures of RMS Pn, Sn, Lg, and late coda amplitudes. Measurements were taken from seismograms filtered at several narrow frequency bands centered from 0.5 to 8.0 Hz, where signal levels ... |
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| Crustal Heterogeneity in the Basin and Range, |
14 AUG 1995 |
10 pages |
| Authors:
A. Levander; S. P. Larkin; L. M. La Flame; S. Pullammanapallil; TEXAS UNIV AT AUSTIN INST FOR GEOPHYSICS
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| We are investigating the fine-scale structure of the Earth's crust in order to understand its influence on high frequency (0.5-30 Hz) regional wave propagation. We have developed geologically based stochastic models of crustal heterogeneity for a number of different tectonic provinces and crustal levels. Here we have focused on examining geologic maps from extended terranes, and seismic data from the northern and southern Basin and Range. We have developed two ... |
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