The objective of the work presented here is to develop and evaluate the adequacy of an elastic source description of the near-in surface recordings of ground motion from the underground nuclear test 'Milrow'. Generalized ray, mode and discrete wavenumber techniques have been applied to model four of the available vertical and radial L-7 records. Preliminary results indicate that an elastic description will be adequate for distances greater than 7 km. No clear azimuthal trends are manifest in...

Topics: DTIC Archive, Cole, David M, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...

The objective of the work presented here is to develop and evaluate the adequacy of an elastic source description of the near-in surface recordings of ground motion from the underground nuclear test 'Milrow'. Generalized ray, mode and discrete wavenumber techniques have been applied to model four of the available vertical and radial L-7 records. Preliminary results indicate that an elastic description will be adequate for distances greater than 7 km. No clear azimuthal trends are manifest in...

Topics: DTIC Archive, Cole, David M, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...

The objective of the work presented here is to develop and evaluate the adequacy of an elastic source description of the near-in surface recordings of ground motion from the underground nuclear test 'Milrow'. Generalized ray, mode and discrete wavenumber techniques have been applied to model four of the available vertical and radial L-7 records. Preliminary results indicate that an elastic description will be adequate for distances greater than 7 km. No clear azimuthal trends are manifest in...

Topics: DTIC Archive, Cole, David M, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...

The first part compares the Mueller Murphy and Helmberger Hadley source representations and investigate whether there are any features of the near-field observations which tend to favor one over the other. The scaling relations in the two formalisms are such that the spectra are virtually indistinguishable between 2 and 5 Hz. Although the Mueller Murphy source is too rich in high frequency energy, a moderately low Q value for the near-field crust can make it agree with the observations. In the...

Topics: DTIC Archive, Barker, Jeffrey S, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSIONS,...

A regional event discriminant is being developed and tested based on the waveform of high frequency P sub n. The data base being used in the development consists of signals from explosions and earthquakes recorded on the western U.S. digital network. It has been discovered that at most stations the waveform of P sub n onset is remarkably stable and different from the corresponding waveforms from earthquakes. A forward modeling study of broad band explosion P sub n's revealed that the...

Topics: DTIC Archive, Burdick, L J, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...

The objective of the work presented here is to develop and evaluate the adequacy of an elastic source description of the near-in surface recordings of ground motion from the underground nuclear test 'Milrow'. Generalized ray, mode and discrete wavenumber techniques have been applied to model four of the available vertical and radial L-7 records. Preliminary results indicate that an elastic description will be adequate for distances greater than 7 km. No clear azimuthal trends are manifest in...

Topics: DTIC Archive, Cole, David M, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...

It is unlikely that regional data recorded at a newly installed array of stations could be used immediately to reliably discriminate events because of uncertainties about the local characteristics of wave propagation. However, the stations would immediately begin to record P sub nl data from small local events. This raises the possibility that the earthquake data base could be used to calibrate the array for discrimination purposes. The relationships is studied between long period P sub nl data...

Topics: DTIC Archive, Burdick, L J, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *SEISMIC DETECTION, SEISMOLOGY

Time domain waveform modeling studies of short period P sub nl and high frequency P sub n have been carried out in an attempt to improve event discrimination capabilities with regional data. The purpose was to develop discriminants with a well understood physical basis which could be reliably transported to different areas of the world. The study of P sub nl involved adapting methods developed to fit long period data for observations with periods as short as two seconds. To accomplish this, we...

Topics: DTIC Archive, Burdick, L J, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *SEISMIC DETECTION,...

It is well established that near fields records of nuclear explosions can be analyzed to obtain detailed information about the seismic source function and its dependence on yield. This information is generally formulated in terms of parametrized models for the RDP and for the test site crustal structure. In this study, we review the results of forward modeling studies to obtain the source and structure parameters for Pahute Mesa. These models fit the observed near field records well, but there...

Topics: DTIC Archive, Burdick, L J, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSIONS, *SEISMIC...

The objective of the work presented here is to develop and evaluate the adequacy of an elastic source description of the near-in surface recordings of ground motion from the underground nuclear test 'Milrow'. Generalized ray, mode and discrete wavenumber techniques have been applied to model four of the available vertical and radial L-7 records. Preliminary results indicate that an elastic description will be adequate for distances greater than 7 km. No clear azimuthal trends are manifest in...

Topics: DTIC Archive, Cole, David M, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...

Although the main problems with test ban treaty monitoring involve improving methods for discrimination of source types, there are certain problems of continuing interest in the field of yield estimation. In terms of short period body waves and the dependence of mb on yield, these involve the effects of anelastic attenuation, pP, nonlinear phenomena such as spall and influence of 3D structure on amplitude,. A related problem involves the transportability of yield scaling relation, hips between...

Topics: DTIC Archive, Burdick, L J, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *YIELD(NUCLEAR EXPLOSIONS),...

Two regional discriminants are being developed and tested on western U.S. data bases. The first is based on the observation that the onset of the Pn waveform is stable in character and typically much different than most earthquake Pn waveforms. The results were reasonably consistent between stations. The average waveform at a fixed station is exceptionally consistent between the Pahute Mesa and Yucca test sites indicating that average Pn waveform is a stable function of time. Synthetics were...

Topics: DTIC Archive, Burdick, L J, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *COMPARISON, *SEISMIC...

The objective of the work presented here is to develop and evaluate the adequacy of an elastic source description of the near-in surface recordings of ground motion from the underground nuclear test 'Milrow'. Generalized ray, mode and discrete wavenumber techniques have been applied to model four of the available vertical and radial L-7 records. Preliminary results indicate that an elastic description will be adequate for distances greater than 7 km. No clear azimuthal trends are manifest in...

Topics: DTIC Archive, Cole, David M, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...

Most regional discriminants developed to date have been based purely on empirics, and many rely on the characteristics of spectra. At Woodward Clyde, a unique type of time domain discriminant has been developed based on a theoretical understanding of wave propagation and the direct identification of depth phases in P sub n and Pg. This work has involved original basic research into the nature of the short period P sub n waveform and the effect of pP sub n on it; development of an understanding...

Topics: DTIC Archive, Burdick, L J, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *WAVE PROPAGATION, *SEISMIC...

The first part of this report presents a method for simultaneous inversion of near-field explosion waveforms for parameters of the source and structure. The inversion automatically provides information on the trade offs between parameters and error analyses of the resultant models. The source may be parameterized by any of several effective source functions. The structure is parameterized as a layered stack of gradients defined by the velocity at the top of the layer, the velocity gradient...

Topics: DTIC Archive, Barker,Jeffrey S, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *SEISMIC DATA, *SEISMIC...

The objective of the work presented here is to develop and evaluate the adequacy of an elastic source description of the near-in surface recordings of ground motion from the underground nuclear test 'Milrow'. Generalized ray, mode and discrete wavenumber techniques have been applied to model four of the available vertical and radial L-7 records. Preliminary results indicate that an elastic description will be adequate for distances greater than 7 km. No clear azimuthal trends are manifest in...

Topics: DTIC Archive, Cole, David M, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...

Laboratory evidence indicates that when strains exceed 10 to the -6 in media under low confining pressure, certain nonlinear processes begin to occur. They are manifested by a reduction in apparent Q. Since direct measurement of near field strain are rare, it has been difficult to evaluate whether or not this phenomenon is significant near to realistic seismic sources. A high frequency theory for computing stresses and strains using generalized ray theory has been developed. It can be shown...

Topics: DTIC Archive, Burdick,L J, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *EXPLOSIONS, *EARTHQUAKES,...

The objective of the work presented here is to develop and evaluate the adequacy of an elastic source description of the near-in surface recordings of ground motion from the underground nuclear test 'Milrow'. Generalized ray, mode and discrete wavenumber techniques have been applied to model four of the available vertical and radial L-7 records. Preliminary results indicate that an elastic description will be adequate for distances greater than 7 km. No clear azimuthal trends are manifest in...

Topics: DTIC Archive, Cole, David M, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...

The objective of the work presented here is to develop and evaluate the adequacy of an elastic source description of the near-in surface recordings of ground motion from the underground nuclear test 'Milrow'. Generalized ray, mode and discrete wavenumber techniques have been applied to model four of the available vertical and radial L-7 records. Preliminary results indicate that an elastic description will be adequate for distances greater than 7 km. No clear azimuthal trends are manifest in...

Topics: DTIC Archive, Cole, David M, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...

The objective of the work presented here is to develop and evaluate the adequacy of an elastic source description of the near-in surface recordings of ground motion from the underground nuclear test 'Milrow'. Generalized ray, mode and discrete wavenumber techniques have been applied to model four of the available vertical and radial L-7 records. Preliminary results indicate that an elastic description will be adequate for distances greater than 7 km. No clear azimuthal trends are manifest in...

Topics: DTIC Archive, Cole, David M, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...

The objective of the work presented here is to develop and evaluate the adequacy of an elastic source description of the near-in surface recordings of ground motion from the underground nuclear test 'Milrow'. Generalized ray, mode and discrete wavenumber techniques have been applied to model four of the available vertical and radial L-7 records. Preliminary results indicate that an elastic description will be adequate for distances greater than 7 km. No clear azimuthal trends are manifest in...

Topics: DTIC Archive, Cole, David M, WOODWARD-CLYDE CONSULTANTS PASADENA CA, *NUCLEAR EXPLOSION TESTING,...