| Improved Methods for Regionalized Surface Wave Analysis |
SEP 1997 |
68 pages |
| Authors:
J. L. Stevens; K. L. McLaughlin; MAXWELL TECHNOLOGIES INC SAN DIEGO CA
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 | We develop optimized methods for measuring surface waves for event screening under a CTBT. The optimization techniques are: a regionalized earth model, phase-matched filtering, path corrected surface wave spectral magnitude; maximum likelihood magnitudes and upper bounds. A regionalized earth model is developed by tomographic inversion of surface wave data starting with the Crust 5.1 earth models, and using dispersion measurements from PIDC data, historic explosion data, and data sets from ... |
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| Physical Mechanisms of Quarry Blast Sources |
JAN 97 |
52 pages |
| Authors:
T. G. Barker; K. L. McLaughlin; J. Bonner; MAXWELL TECHNOLOGIES INC SAN DIEGO CA FEDERAL DIV
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| Models of quarry blasts may serve to develop efficient and robust methods for discriminating quarry blasts from other sources. In this report, we present progress on modeling quarry blasts at the Chemline quarry in central Texas and the Black Thunder mine in the Powder River Basin of Wyoming. We observe strong variations in near field ground motions at the Black Thunder mine. Using estimates of site response derived from signal ... |
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| Regionalized Maximum Likelihood Surface Wave Analysis |
SEP 96 |
27 pages |
| Authors:
J. L. Stevens; K. L. McLaughlin; S-CUBED LA JOLLA CA
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| We develop a method for regionalization of surface wave magnitudes, replacing the traditional Ms measurement with a new type of magnitude, the scalar moment, derived from the equations for surface waves from point sources in layered media. This has the effect of minimizing the frequency dependence and distance dependence of the magnitude, and allows worldwide regionalization so that the magnitude is a consistent measure of source size for any source ... |
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| Network Identification Capability Evaluation (NICE) of Regional Networks |
JUL 94 |
51 pages |
| Authors:
T. G. Barker; K. L. McLaughlin; J. L. Stevens; S-CUBED LA JOLLA CA
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| The computer program NICE, for Network Identification Capability Evaluation, was written to assess the ability of a seismic network to discriminate earthquakes from explosions. In this report on the progress during the first phase of a two-year project, we describe enhancements to the program which allow assessment of regional networks and discriminants. The enhanced program, called XCNICE simulates the detection, location and identification of a suite of events using a ... |
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| Numerical Models of Quarry Blast Sources: The Effects of the Bench |
01 MAY 93 |
39 pages |
| Authors:
T. G. Barker; K. L. McLaughlin; J. L. Stevens; S. M. Day; MAXWELL LABS INC SAN DIEGO CA
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| A set of finite difference calculations were performed to modal the effects of a quarry bench on the excitation of seismic signals from a quarry. This work complements other S-CUBED research on the nonlinear behavior of the quarry blast source (spall from the quarry face) and interference effects from ripple-fired explosions. We find that the excitation of seismic phases depends strongly on the location of the explosion source near the ... |
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| Numerical Simulation of Quarry Blast Sources |
01 JAN 93 |
66 pages |
| Authors:
T. G. Barker; K. L. McLaughlin; J. L. Stevens; S-CUBED LA JOLLA CA
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| Quarry blast sources are developed based on well-documented blasting practices from decades of blasting in quarries and used to simulate seismic signals from quarry blasts, and to examine the 'hide-in-quarry blast' scenario for evading detection of nuclear weapons testing. Blasting is designed to break rock through spallation, and the resultant spall is an important part of the quarry blast source. The quarry blast source models include the finite size of ... |
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| Three-Dimensional Finite Difference Modeling of Surface Wave Propagation Across the Barents Shelf |
OCT 91 |
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| Authors:
K. L. McLaughlin; T G. Barker; J. L. Stevens; B. Shkoller; S. M. Day; S-CUBED LA JOLLA CA
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 | A three-dimensional (3D) finite difference simulation has been conducted of surface waves propagating across a laterally heterogeneous velocity and density model of the Barents Shelf. The 3D model encompasses a region of 1620 by 810 km to a depth of 210 km. The calculations were designed to model 0. 02 to 0.05 Hz surface waves from an isotropic source at Novaya Zemlya in a 3D heterogeneous model. Extensive focusing/defocusing of ... |
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| Two-Dimensional Axisymmetric Calculations of Surface Waves Generated by an Explosion in an Island, Mountain and Sedimentary Basin |
OCT 91 |
50 pages |
| Authors:
J. L. Stevens; K. L. McLaughlin; S. M. Day; B. Shkoller; S-CUBED LA JOLLA CA
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| The generation of long period (20-50 second) surface waves by an explosion on an island, inside a mountain, or near a material discontinuity is studied using two-dimensional axisymmetric finite difference calculations. The generation of surface waves can be reduced substantially if the explosion is close to a vertical boundary such as a material velocity reduction, mountain slope, or island/ocean boundary. This occurs because the horizontal components of the static stress ... |
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| Development of a Comprehensive Seismic Yield Estimation System for Underground Nuclear Explosions |
MAY 91 |
36 pages |
| Authors:
J. R. Murphy; J. L. Stevens; D. C. O'Neill; B. W. Barker; K. L. McLaughlin; S-CUBED LA JOLLA CA
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| This report summarizes the progress which has been achieved during the past year in the development of a comprehensive new seismic yield estimation system for underground nuclear explosions. Specifically, a preliminary prototype version of this system, which has now been successfully implemented at the DARPA Center for Seismic Studies (CSS), is described in detail and its functionality is graphically illustrated through a sample application to the seismic data recorded from ... |
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| Two and Three Dimensional Numeical Modeling of Surface Waves from Underground Explosions, Analysis of Data from the Soviet JVE, and Magnitude/ Yield Relations for East Kazakh Explosions |
JAN 91 |
58 pages |
| Authors:
K. L. McLaughlin; T. G. Barker; S. M. Day; B. Shkoller; J. L. Stevens; S-CUBED LA JOLLA CA
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| We perform three dimensional finite difference simulation of surface waves generated at the Amchitka test site and find that the Aleutian arc structure causes higher amplitudes to the east relative to the north and south, and that this structure can also generate rapid amplitude changes over a small range of azimuths and generate Love waves with substantial amplitudes. A series of two-dimensional finite difference simulations show that long period surface ... |
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| Effects of Subduction Zone Structure on the Propagation of Explosion- Generated Long-Period Rayleigh Waves |
JAN 91 |
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| Authors:
K. L. McLaughlin; T. G. Barker; S. M. Day; B. Shkoller; J. L. Stevens; S-CUBED LA JOLLA CA
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| 3D linear elastic finite difference calculations were used to investigate effects of near-source scattering on long-period surface waves radiated by shallow explosions located in the arc of a subduction zone. These simulations were motivated by the teleseismic Rayleigh-wave amplitude patterns of explosions detonated at the Amchitka test site. Amplitude patterns of these explosion-generated 20-40 second surface waves show evidence of both tectonic release and source-receiver path effects. A 3D velocity ... |
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| An Analysis of the Effects of Spall on Regional and Teleseismic Waveforms Using Two-Dimensional Numerical Modeling of Underground Explosions |
MAY 90 |
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| Authors:
T. G. Barker; S. M. Day; K. L. McLaughlin; B. Shkoller; J. L. Stevens; S-CUBED LA JOLLA CA
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| A simple, physical model for spall is developed by comparing the waveforms from two-dimensional explosion simulations with the waveforms generated by a one-dimensional explosion plus a shallow tension crack in the same layered medium. The tension crack is parameterized by its radius, depth, and a distribution of takeoff velocities over its surface. This model accurately reproduces the P-waves from the two-dimensional simulations. The parameters for the spall model a ... |
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| Implications of Explosion Generated Spall Models: Regional Seismic Signals |
MAY 90 |
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| Authors:
K. L. McLaughlin; T. G. Barker; S. M. Day; S-CUBED LA JOLLA CA
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| The contribution of the spall source to the short period regional explosion seismogram is studied using new parametric models for the spallation seismic source derived from (2-D) axisymmetric nonlinear finite difference simulations for underground nuclear explosions. It is concluded that in high- velocity crustal structures spall may be a significant source of short period Lg and may significantly affect the Pg excitation. Regional phase excitation from a vertical point force ... |
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| Regional Discrimination of Quarry Blasts, Earthquakes and Underground Nuclear Explosions |
07 APR 89 |
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| Authors:
T. J. Bennett; B. W. Barker; K. L. McLaughlin; J. R. Murphy; S-CUBED LA JOLLA CA
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| The investigations conducted under this contract focused on analyses of the higher-frequency phases observed at regional distances from underground nuclear explosions, earthquakes, and commercial blasts. These analyses systematically compared the time-domain amplitude and spectral characteristics of the observed regional seismic signals in order to identify diagnostic differences which would be indicative of source type. The sources were located in three tectonic environments: (1) eastern North America, (2) southern Soviet Union, ... |
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| Effects of Depth of Burial and Tectonic Strain Release on Regional and Teleseismic Explosion Waveforms |
04 NOV 88 |
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| Authors:
K. L. McLaughlin; T. G. Barker; S. M. Day; B. Shkoller; J. L. Stevens; S-CUBED LA JOLLA CA
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| The seismic motions from nonlinear two dimensional (2D) axisymmetric finite difference calculations of underground explosions are propagated to regional and teleseismic distances. Synthetic seismograms are computed and examined to study the effects of depth of burial, medium structure, and prestress on seismic waveforms. The elastodynamic representation theorem is used to couple the results of finite difference source calculations to regional Green's functions computed using a wavenumber integration algorithm. The 2D ... |
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| Yield Estimation of Novaya Zemlya Explosions from Short-Period Body Waves |
AUG 88 |
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| Authors:
W. W. Chan; K. L. McLaughlin; R. K. Cessaro; M. E. Marshall; A. C. Lees; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| This study investigates the characteristics of Novaya Zemlya explosions using various body wave phases. This information will be used to calibrate the yields of these explosions. The azimuthal variation of amplitude for the Novaya Zemlya explosions as seen from WWSSN recordings indicates that there is a strong component of near-source heterogeneity due to multiple source excitation, near-source structural heterogeneity, or source anisotropy. The systematic azimuthal variation in amplitude may be ... |
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| Comprehensive Magnitude Yield Estimation for Nuclear Explosions: A maximum Likelihood General Linear Model (MLE-GLM88) |
JUN 88 |
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| Authors:
W. W. Chan; K. L. McLaughlin; R-s. Jih; M. E. Marshall; R. A. Wagner; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| This study performs maximum likelihood event magnitudes and station effects for 111 nuclear explosions from more than 8 different test sites using a general linear model. The estimates are performed for the three P-wave phases a, b, and max by considering the signals, non-detection, and clipping information. The bias between a model that does not include censoring effects from non- detection and clipping is demonstrated. The maximum-likelihood magnitude estimates are ... |
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| Finite Difference Cratering Support. Analysis of Regional Data from Cratering and Non-Cratering Nuclear Explosions |
FEB 88 |
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| Authors:
I. N. Gupta; K. L. McLaughlin; R. W. Wagner; TELEDYNE GEOTECH ALEXANDRIA VA
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| A comparison of regional phases generated by contained and cratering nuclear explosions is made by examining the amplitudes of various phases and by spectral analyses. Using Ringdal's maximum likelihood method, in which one can also make use of clipped readings as well as noise measurements, amplitudes of the regional phases Pn, Pg, Lg (corrected for spatial attenuation) and the ratio Pmax/Pa (where Pmax is the largest amplitude in the first ... |
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| Maximum-Likelihood Multichannel Deconvolution of P Waves at Seismic Arrays |
NOV 87 |
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| Authors:
Z. A. Der; A. C. Lees; W. W. Chan; R. H. Shumway; K. L. McLaughlin; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| The results of maximum-likelihood multichannel deconvolution applied to array recordings and three component station networks for teleseismic P waves, are presented and interpreted in terms of possible surface reflections and other arrivals from explosions conducted at many of the world's major nuclear test sites. The deconvolution method utilizes the well known fact that P wave spectra can be decomposed into source and receiver spectral factors. The source functions obtained in ... |
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| Miscellaneous Studies in Decoupling |
NOV 87 |
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| Authors:
I. N. Gupta; K. L. McLaughlin; R. A. Wagner; T. W. McElfresh; M. E. Marshall; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| Keywords: Decoupling; Regional phases; Scaled depth; Frequency dependent; Strain dependent. Contents: Analysis of Project Cowboy Strong Motion Data; Effect of Scaled Depth on Regional Phases; Deconvolution and Spectral Ratios from Soviet Salt Shots; and Deconvolution and Spectral Ratios from Soviet Salt Short; and Analysis of Data from Soviet Salt Shots with Known Yields. |
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| Finite Difference Simulations of Rayleigh Wave Scattering by 2-D Rough Topography |
NOV 86 |
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| Authors:
K. L. McLaughlin; R. S. Jih; TELEDYNE GEOTECH ALEXANDRIA VA
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| Rayleigh waves normally incident upon 2 D simple or rough topographic structures are simulated by the linear finite difference method to study the attenuation, transmission, and reflection of Rayleigh waves and to measure the Rayleigh-to-P and -SV bodywave conversion. For simple ramp structures, transmission, reflection, and scattering depend on the sign of change of slope of the topographic feature, as well as the ratio of the ramp height to the ... |
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| Studies in Decoupling |
NOV 86 |
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| Authors:
I. N. Gupta; K. L. McLaughlin; R. A. Wagner; T. W. McElfresh; M. E. Marshall; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| This report contains studies on seismic decoupling using Salmon, Sterling, and Pahute Mesa Nuclear Explosions, and on strain and frequency dependent attenuation estimates in salt from salmon and sterling near-field recording. An understanding of the frequency dependence of decoupling is essential for monitoring nuclear explosions detonated in large underground cavities. Analysis of available data from the nuclear explosions Salmon and Sterling recorded at shot-receiver distances of 16,32, and 27 km, ... |
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| Effects of Local Geologic Structure for Yucca Flats, NTS, Explosion Waveforms: 2-Dimensional Linear Finite Difference Simulations |
OCT 86 |
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| Authors:
K. L. McLaughlin; L. M. Anderson; A. C. Lees; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| Two-dimensional linear elastic finite difference calculations were performed for two-dimensional geologic model of Yucca Flats, Nevada Test Site, Nevada. The calculations were used to produce synthetic teleseismic P-wave seismograms for explosive line sources in Yucca Flats. P-wave coda (first 5 seconds) is observed to be highly dependent on takeoff angle for the teleseismic synthetics. P-wave coda varies with the position of the source in the valley structure and may produce ... |
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| Finite Difference Cratering Support. Magnitude Determination of Cratering and Non-Cratering Nuclear Explosions |
MAY 85 |
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| Authors:
K. L. McLaughlin; I. N. Gupta; R. Wagner; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| The ratio of the 'a' phase and 'max' phase of presumed Shagan River contained and cratering explosions are studied across the WWSSN network of short period stations. The amplitude of the 'a' phase of the presumed cratering explosion of Jan 15, 1965 is found to e systematically larger in comparison to the 'max' amplitude of this cratering explosion when compared to contained explosions in the vicinity of the cratering explosion. ... |
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| Pearce Focal Sphere Analysis of Explosion and Earthquake Mechanisms |
10 NOV 1983 |
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| Authors:
K. L. McLaughlin; D. W. Rivers; M. A. Brennan; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| Pearce's (1977) processor for analyzing seismic focal mechanisms has been implemented on two seismic analysis systems, and it has been given limited testing for use as a discrimination aid. This algorithm uses relative amplitudes of the pP and sP depth phases with respect to the P-wave amplitude at each station in a network. If pP and/or sP cannot be identified, then the amplitude of the P-wave coda at the anticipated ... |
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| Evaluation of the RSTN (Regional Seismic Test Network) Network and Further Improvement to Automatic Association |
30 OCT 1983 |
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| Authors:
R. R. Blandford; J. Goncz; R. Baumstark; K. L. McLaughlin; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| The Regional Seismic Test Network (RSTN) is a 5-station seismic network designed to monitor regional seismicity on the scale of a large continental shield. The RSTN serves as a prototype for a network that could be deployed for test ban treaty verification. Both regional and teleseismic signals are digitally recorded for three components of earth motion in three overlapping frequency bands covering 0.02 to 10 Hz. The approach of this ... |
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Reports by Author
