| Systematic Differences in the Spectral Excitation of Pn and Lg by the Last Lop Nor Explosions and Nearby Earthquakes: Implications on the Pn/Lg Spectral Ratio Discriminant |
01 FEB 1998 |
43 pages |
| Authors:
Jiakang Xie; SAINT LOUIS UNIV MO DEPT OF EARTH AND ATMOSPHERIC SCIENCES
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 | PD and Lg spectra from the last eight Lop Nor explosions and many nearby earthquakes are collected from many broadband seismic stations, and analyzed to obtain source spectral characteristics and path Q. Pn spectra are unstable in amplitude with varying paths and source mechanisms. Much improvement has been made to stablize Pn spectral analysis. The main findings of this study include: (1) Pn spectra from explosions ... |
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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
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 | 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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| Effect of 3-D Heterogeneities and Topography on Seismic Wave Propagation and the Use of Empirical Green's Functions for Source Characterization and Discrimination |
01 SEP 96 |
174 pages |
| Authors:
Michel Bouchon; Ningya Cheng; Matthias G. Imhof; Yingping Li; William L. Rodi; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
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| We investigate two topics related to seismic nuclear monitoring and discrimination. The first is elastic wave propagation in complex earth models containing lateral variations in elastic properties or irregular interfaces. We describe an improved boundary element technique based on the conjugate gradient method and apply it to study the effects of surface topography. We also investigate the usefulness of a hybrid modeling method that combines multiple multipole and finite element ... |
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| Analysis of 3D Complex Structure and Heterogeneity Effects on Formation and Propagation of Regional Phases in Eurasia |
13 DEC 94 |
66 pages |
| Authors:
Thorne Lay; Ru-Shan Wu; CALIFORNIA UNIV SANTA CRUZ INST OF TECTONICS
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| This is the final report for this grant to develop new three- dimensional wave propagation techniques for high frequency waves in heterogeneous media. The report is divided into four sections, each being a published paper sponsored by this grant. In the first section we formulate a one-way wide-angle elastic wave propagation method for arbitrarily heterogeneous media in both the space and wavenumber domains using elastic Rayleigh integrals and local elastic ... |
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| Advanced Waveform Research Methods for GERESS Recordings |
15 JUN 94 |
98 pages |
| Authors:
H. -p. Harjes; M. Jost; J. Schweitzer; G. Bokelmann; BOCHUM UNIV (GERMANY F R)
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| Two major research projects were finished and separated papers are included in this report. The first paper (Jost et al) summarizes the GERESS recordings of underground nuclear explosions. Path-specific detection thresholds at GERESS are derived for NTS, Tuamotu Archipelago, Kazakhstan, Novaya Zemlya, and Lop Nor. These empirical detection thresholds substantially deviate from those calculated from global amplitude-distance relations (i.e. Gutenbergy- Richter). This case history again casts some doubts on theoretical ... |
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| Single-Station Backazimuth Estimation from P- and Rg-Waves at Regional Distance in the Central Appalachians. |
30 NOV 1993 |
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| Authors:
Martin C. Chapman; Shaosong Huang; J. A. Snoke; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF GEOLOGICAL SCIENC ES
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| The study examines the accuracy of single-station backazimuth measurements from polarization analysis of near regional P- and Rg-wave arrivals. The data set consists of 37 signals from mining explosions in the distance range 100 to 300 km, recorded at station BLA, Blacksburg, Virginia. The station-source backazimuth estimates derived from the three-component station are compared with results derived from independent information, primarily from regional network epicenter locations. For P-wave signal/noise ratios ... |
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| Advanced Discrimination Technology |
11 NOV 93 |
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| Authors:
L. J. Burdick; D. V. Helmberger; C. K. Saikia; WOODWARD-CLYDE CONSULTANTS PASADENA CA
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| In this era of increased concern for the proliferation of nuclear weapons, the need for effective seismic discrimination techniques is as important as ever. As more countries attain or near the technology threshold needed to develop nuclear weapons, more regions of the world need to be monitored for verification purposes. Many of these countries are within tectonically active environments, and since small magnitude events are too weak to be seen ... |
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| Advanced Waveform Research Methods for GERESS Recordings. |
15 APR 1993 |
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| Authors:
H. P. Harjes; M. Jost; J. Schweitzer; J. Wuster; BOCHUM UNIV (GERMANY F R)
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| The GERESS array project is a cooperative research program, jointly undertaken by Southern Methodist University Dallas (USA) and Ruhr-University Bochum in Germany. It is part of a multi-array network which includes NORESS, ARCESS, and FINESA in Scandinavia. This report summarizes research activities carried out at the data center in the Institute of Geophysics in Bochum during 1992. GERESS data are continuously transmitted from the array hub in Bavaria to Bochum ... |
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| Wave Propagation Characteristics of Short-Period Crustal Phases Near ARCESS and NORESS |
FEB 93 |
54 pages |
| Authors:
Kristin S. Vogfjord; Charles A. Langston; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF GEOSCIENCES
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| Wave propagation of crustal phases near the ARCESS array is examined and compared to characteristics near the NORESS array, with emphasis on Lg and its composition. f-k analysis is applied to the data, to identify arrivals in the records, then a composite of array beams is used to approximate each event. Record sections of composite-seismograms are constructed for different directions from ARCESS, to study propagational characteristics with distance and azimuth. ... |
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| Computational Modeling of Metal Matrix Composite Materials-I. Isothermal Deformation Patterns in Ideal Microstructures. |
1993 |
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| Authors:
P. E. McHugh; R. J. Asaro; C. F. Shih; BROWN UNIV PROVIDENCE RI DEPT OF ENGINEERING
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| The mechanical behavior of particulate reinforced mmc, in particular an sic reinforced al-3wt% cu model system, was analyzed numerically. the computational micromechanics approach was taken, i.e. a detailed representation of microstructure in which the material was characterized by a finite deformation, thermo-elastic-viscoplastic crystallographic theory. individual matrix grains and reinforcing particles were represented, in the context of two dimensional repeating unit cell models. the performance of the microstructure under variation in ... |
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| Computational Modeling of Metal Matrix Composite Materials-III. Comparisons With Phenomenological Models. |
1993 |
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| Authors:
P. E. McHugh; R. J. Asaro; C. F. Shih; BROWN UNIV PROVIDENCE RI DEPT OF ENGINEERING
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| The mechanical behavior of particulate mmc, an sic reinforced al-3wt% cu model system, was analyzed numerically and analytically. the results of computational micromechanics modeling are compared with those of simpler analytical/numerical models. models that predict overall composite behavior make use of a result, valid for incompressible materials in small strain, that both pure matrix material and composite harden with the same hardening exponent. results of micromechanical simulations, with power-law hardening ... |
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| Computational Modeling of Metal Matrix Composite Materials-IV. Thermal Deformations. |
1993 |
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| Authors:
P. E. McHugh; R. J. Asaro; C. F. Shih; BROWN UNIV PROVIDENCE RI DEPT OF ENGINEERING
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| The mechanical behavior of particulate reinforced mmc, an sic reinforced al-3wt% cu model system, was analyzed using the computational micromechanics approach. the microscale effects of thermo-mechanical processing is investigated in detail. two ideal processes are considered. the first represents a simple quench and the second combines a high temperature compression with a quench. these processes, through applied deformation and thermal expansion mismatch, produce inhomogeneous, and localized, stress and plastic strain ... |
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| Cavity Formation During Tensile Straining of Particulate and Short Fibre Metal Matrix Composites. |
1993 |
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| Authors:
A. F. Whitehouse; T. W. Clyne; CAMBRIDGE UNIV (UNITED KINGDOM) DEPT OF METALLURGY AND MATERIALS SCIENCE
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| The formulation of cavities in commercially pure aluminum composites, made by both powder and casting routes and reinforced with alumina, has been monitored using periodic density measurements during tensile testing and microstructural examinations. stable cavities always form well before final failure, usually adjacent to the reinforcement, particularly when it is elongated in the loading direction and has a relatively flat surface normal to the stress axis. sharp corners are not ... |
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| Fracture Mechanics of Ti/Al2O3 Interfaces. |
1993 |
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| Authors:
H. F. Wang; W. W. Gerberich; C. J. Skowronek; MINNESOTA UNIV MINNEAPOLIS DEPT OF CHEMICAL ENGINEERING AND MATERIALS SCIENCE
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| Measurement of mixed mode interfacial fracture toughness in ti/al2o3 bimaterial couples has been accomplished by the four-point bending test of sandwich specimens with symmetrical cracks for different processing temperatures and thicknesses of ti interlayers. fracture surfaces and sample cross sections were analyzed by sem, wps, edax, epma and aes. the interfacial fracture toughness measured with four-point bending tests increases with increasing applied bonding temperature up to 950c. above this temperature ... |
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| Resistive Transition and Fluctuation Conductivity in YBaCuO-Ag Nonrandom Composites. |
1993 |
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| Authors:
P. Rodrigues Jr.; L. Ghivelder; P. Pureur; S. Reich; UNIVERSIDADE FEDERAL DO RIO GRANDE DO SUL PORTO ALEGRE (BRAZIL)*
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| Detailed resistivity measurements were made on yba2cu3o7-ag nonrandom composites, prepared by coating the superconducting grains with silver. investigated were samples with 6, 11, and 23 wt%ag and yba2cu3o7 reference material. the results show that the resistive transition proceeds in two steps. as the temperature is lowered, the superconducting transition first stabilizes inside the grains, followed by the establishment of superconductivity through the grain boundaries, or weak-links. silver addition to yba2cu3o7 ... |
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| Seismic Velocity Structure and Event Relocation in Kazakhstan from Observation and Modeling of Secondary P Phases |
20 APR 92 |
32 pages |
| Authors:
H. R. Quin; C. H. Thurber; WISCONSIN UNIV-MADISON
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| Data from presumed explosions in Kazakhstan recorded by NRDC/SAS stations were analyzed to model the crustal structure of the region and to examine the use of arrival times of secondary P phases in event location. Data from 20 events were modeled using a reflectivity algorithm. A good fit to the first five seconds of the P wave was obtained in the epicentral distance range of 100 to 300 km. The ... |
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| Regional Seismograms: Attenuation and Scattering |
06 MAR 92 |
364 pages |
| Authors:
M. N. Toksoz; E. E. Charrette; N. Cheng; A. M. Dainty; B. Mandal; MASSACHUSETTS INST OF TECH CAMBRIDGE EARTH RESOURCES LAB
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| The objective of this study was to examine the influence of attenuation and scattering on regional high frequency seismograms. This report consists of a Ph.D. thesis, a paper, and three preprints of papers either submitted or in preparation, on work supported by this project; they include both basic work on attenuation, scattering and anisotropy, and applications to regional seismograms. The Ph.D. thesis discusses the application of the finite difference method ... |
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| Waveform Inversion of Seismic Data |
01 JAN 92 |
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| Authors:
Peter R. Shaw; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF GEOLOGY AND GEOPHYSICS
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| Long range scientific objectives are to understand the variations of the oceanic crust as expressed by variabilities in its seismic velocity structure. Such variations occur both with geological age (caused by hydrothermal alteration and pore sealing) and spatially, such as, distance along-ridge (variations caused by ridge segmentation, faulting, hydrothermal cells, etc). For this project I have developed and applied seismic waveform inversion methods that allow variations in seismic velocities from ... |
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| Studies of Near-Source and Near-Receiver Scattering and Low-Frequency Lg from East Kazakh and NTS Explosions |
04 DEC 91 |
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| Authors:
I. N. Gupta; C. S. Lynnes; R. A. Wagner; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| This study consists of three sections: (1) Evidence for Rg-to-P scattering in Teleseismic P-coda and Rg-to-S Scattering in Regional Lg of East Kazakh Explosions, (2) Generation of Low-frequency Lg from NTS Explosions, and (3) An Array Study of the Effects of Known Local Scatterer on Regional Phases. In Section A, analysis of teleseismic data from Degelen and Shagan River explosions recorded at NORSAR and EKA arrays suggests that the low-frequency ... |
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| Wave Propagation at Regional Distances |
23 APR 91 |
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| Authors:
Charles A. Langston; PENNSYLVANIA STATE UNIV UNIVERSITY PARK
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| Wave propagation in Fennoscandia is generally understandable in terms of simple plane layered structure models. Although the data show deviations from such models in terms of effects of layer dip, discrete phases are generated by these crust and mantle structures and are not significantly degraded by heterogeneity. Phase attributes, such as time and phase velocity, can be used to accurately identify arrivals. It was found that S waves are often ... |
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| A Method to Test the Composite Strength in Fibre Reinforced Materials. |
1991 |
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| Authors:
Von K. Breuer; Th. Jung; TECHNISCHE UNIV CHEMNITZ (GERMANY)
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| This paper concerned mmc in some important way and contained information about, utilized, or discussed these subjects: basic topics:, composite materials, cr mmc, experimental, mmc, theoretical, pmc materials and material types:, (c)f/al, (sic)f/epoxy, al matrix, c fibers, c/al, epoxy matrix, sic fibers, sic/epoxy material characteristics and data fields:, composite strength, interlaminar shear strength miscellaneous and special technical terms:, german papers. |
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| Formation and Propagation of Love Waves in a Surface Layer with a P-Wave Source |
APR 90 |
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| Authors:
A. L. Florence; S. A. Miller; SRI INTERNATIONAL MENLO PARK CA
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| The objective of this research is to investigate experimentally, and support with theoretical calculations, the formation and propagation of Love waves from a P-wave source due to scattering at material heterogeneities. The P- wave source is a spherical piezoelectric crystal cast in a surface layer of rock simulant overlaying a higher impedance granite substrate. Excitation of the piezoelectric crystal with a known voltage applies a spherical compressional pulse of known ... |
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| The Phase-Screen Method for Elastic Wave and Seismic Discrimination |
15 DEC 89 |
82 pages |
| Authors:
Mark D. Fisk; Gary D. McCartor; MISSION RESEARCH CORP SANTA BARBARA CA
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| The phase-screen method to compute elastic vector wave propagation in three-dimensional heterogeneous media is developed, accounting for the difference in phase velocities of the transverse and longitudinal polarizations. The method replaces the heterogeneous medium with a homogeneous one and a set of phase screens. Between the screens the displacement is propagated by the uniform elastodynamic wave equation. The phase of each polarization of the wave, accumulated from propagating in the ... |
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| Analysis of Teleseismic P Wave Amplitude and Coda Variations for Underground Explosions |
01 JAN 89 |
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| Authors:
Thorne Lay; Christopher S. Lynnes; Brian Cohee; MICHIGAN UNIV ANN ARBOR DEPT OF GEOLOGICAL SCIENCES
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| This report presents the results of four investigations which have as their common goal, the development and application of techniques for determining near-source contributions to the observed variations in short-period P wave amplitudes, travel times, waveforms and coda for underground explosions. A waveform modeling analysis of long-period teleseismic SH and SV waves from two large underground explosions at the Southern Novaya Zemlya test site indicates that the appropriate equivalent double ... |
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| Further Studies of Seismic Variability at the Shagan River Test Site |
JAN 88 |
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| Authors:
Brian W. Barker; John R. Murphy; S-CUBED LA JOLLA CA
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| Large samples of teleseismic P wave data recorded from Shagan River underground explosions have been systematically analyzed in an attempt to develop a better quantitative understanding of the sources of m sub b variability observed for these explosions. Results indicate that large differences in station-corrected m sub b residuals between explosions in close proximity are associated with changes in the near-source proximity are associated with changes in the near-source P ... |
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| Source Depths Utilizing Broad Band Data |
11 APR 86 |
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| Authors:
George H. Sutton; Jerry A. Carter; Noel Barstow; RONDOUT ASSOCIATES INC STONE RIDGE NY
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| This report covers the first year's effort of a two year research project to improve our ability to discriminate between nuclear explosions and earthquakes based on the depth of an event determined from local and regional phases. The approach taken has been to improve phase identification and picking abilities for depth phases pP and sP throughy adaptive filtering to reduce effects of mode conversion and scattering. Three-component polarization methods are ... |
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| Attenuation in the Western Great Basin |
11 FEB 86 |
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| Authors:
Keith Priestley; MACKAY SCHOOL OF MINES RENO NV SEISMOLOGICAL LAB
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| In comparing teleseismic P-wave delays in the vicinity of the Central Nevada Test Site in Hot Creek Valley, NV, with P-delay data over a wider region in the Great Basin, we found that upper mantle speeds under Hot Creek Valley stations are higher than the average for the Great Basin as a whole, but lower than those beneath Pahute Mesa. These observations indicate that the caldera complex in Hot Creek ... |
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| Body Wave Magnitudes and Locations of French Underground Explosions at the Mururoa Test Site |
NOV 85 |
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| Authors:
P. D. Marshall; R. C. Lilwall; Penelope J. Warburton; ATOMIC WEAPONS RESEARCH ESTABLISHMENT ALDERMASTON (ENGLAND)
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| Since 1975 the French have conducted underground nuclear weapon tests beneath the Mururoa atoll in the Tuamotu Archipelago in the Southern Pacific. A least squares joint estimate of origin time and epicentre together with a least squares joint estimate of magnitude is presented for presumed explosions in this area. These are based on data taken from bulletins of the International Seismological Centre. Some seismograms, recorded in Canada, are included to ... |
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| Frequency Dependence of Q in the Mantle Underlying the Shield Areas of Eurasia |
11 JAN 85 |
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| Authors:
Z. A. Der; A. C. Lees; V. F. Cormier; L. Anderson; J. Burnetti; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| In Part I; the results of short and intermediate period data analyses for the determination of a frequency dependent Q model of the mantle under the shield areas of Eurasia are presented. The spectra of short period P waves from nuclear explosions in the 1-8 Hz frequency range give t* sub p = approx. 0.15-0. 2 seconds. Part II presents analyses of long period data. Long period multiple S and ... |
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| Detailed Oceanic Crustal Modeling |
07 NOV 1984 |
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| Authors:
D. V. Helmberger; CALIFORNIA INST OF TECH PASADENA SEISMOLOGICAL LAB
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| The research performed under this contract can be divided into 3 main topics: changes in existing methods, Cagniard de-Hoop and WKBJ, which enable construction of synthetics for mixed path simulations; use of long period SH waves with source in the Northwest Atlantic and receivers on the northeast coast of North America to derive an oceanic upper mantle shear velocity model; and a technique based on evaluating the Kirchoff-Helmholtz integral for ... |
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| Active Detection of Tunnels by Induced Seismic Spectra |
SEP 84 |
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| Authors:
R. F. Ballard Jr.; T. B. Kean Ii; R. D. Lewis; G. E. Smith Jr; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS GEOTECHNICAL LAB
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| A series of crosshole tests were conducted at the Colorado School of Mines Test Facility located near Idaho Springs, Colo. The primary objective of the study was to determine the modifications imposed on a seismic signal originating from a repeatable source caused by presence of a tunnel. The seismic source was a modified air gun, designed for generation of midfrequency range P- waves. In this study, 50- to 500 Hz ... |
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| Body and Surface Wave Modeling of Observed Seismic Events |
31 OCT 1981 |
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| Authors:
David G. Harkrider; Donald V. Helmberger; William J. Best; CALIFORNIA INST OF TECH PASADENA SEISMOLOGICAL LAB
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| This research dealt with three main topics: coupling of surface waves in laterally inhomogeneous source regions to teleseismic propagation paths, using regional waveforms to determine the source parameters of moderate-size earthquakes and the application of the Kirchoff-Helmholtz integral to seismic problems. First, the Representation Theorem is used to numerically evaluate the effectiveness of two commonly used algorithms for modeling Rayleigh wave propagation across lateral inhomogenities. Of the two, the conservation ... |
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| Research in Seismology |
31 MAR 1977 |
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| Authors:
Brian J. Mitchell; Otto W. Nuttli; SAINT LOUIS UNIV MO
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| Research for this program period has been concerned with the effect which various propagation effects and source properties have on the spectra and wave forms of body- and surface waves. The research is divided into four different but related reports which are presented in the following sections. The first report is concerned with the scaling of teleseismic P-wave ground-motion spectra of underground nuclear explosions. The second describes the use of ... |
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| Theoretical Amplitudes and Travel Times of Explosion-Generated Seismic PWaves |
05 APR 1967 |
12 pages |
| Authors:
John Roberts; CALIFORNIA UNIV BERKELEY LAWRENCE RADIATION LAB
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| Amplitudes and travel times have been calculated for the first half- cycle of seismic P waves generated by nuclear explosions at distances varying from 140 to 2900 km. The head-wave-body-wave model constructed yields travel times within 13.9 sec of the mean experimental values over the indicated range of distances and also provides an interpretation of the large-small-large nature of the amplitudes. ... |
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Reports by Keyword(s)
PRIMARY WAVES(SEISMIC WAVES)
