Accession Number : ADA192212

Title :   Forward and Inverse Modeling of Near-Field Seismic Waveforms from Underground Nuclear Explosions for Effective Source Functions and Structure Parameters.

Descriptive Note : Final rept. 5 Sep 86-5 Mar 87,

Corporate Author : WOODWARD-CLYDE CONSULTANTS PASADENA CA

Personal Author(s) : Burdick, L J ; Barker, J S

PDF Url : ADA192212

Report Date : 05 Apr 1987

Pagination or Media Count : 127

Abstract : 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 is some question as to how errors in crustal structure might affect seismic source parameters. Furthermore, there is a general need to be able to develop source-structure models in a consistent, unbiased fashion. To address these issues, we have developed a simultaneous inversion for source and structure parameters. In previous reports, we discussed the development of the method and applied it to Pahute Mesa data. In this report, we present an application of an improved technique for inverting for parameters in these types of problems known as the jumping method. A second problem with analysis of near-field records from explosions is that there is some question as to whether crustal materials respond in a linear anelastic or anelastic fashion or whether they have significant nonlinear response because of the high shear strain levels. Near-field data sets from several nuclear explosions and an earthquake are examined to address this question. It is shown that if nonlinear material response occurs it does not have a large enough effect to have a significant effect on data interpretation.

Descriptors :   *NUCLEAR EXPLOSIONS, *SEISMIC DATA, *SEISMIC WAVES, *SEISMOLOGY, *UNDERGROUND EXPLOSIONS, DATA BASES, DATA PROCESSING, EARTH CRUST, EARTHQUAKES, FORWARD AREAS, FUNCTIONS, INVERSION, LEVEL(QUANTITY), MATERIALS, MODELS, NEAR FIELD, NONLINEAR SYSTEMS, PARAMETERS, RECORDS, RESPONSE, SHEAR STRENGTH, SOURCES, STRAIN(MECHANICS), SYNCHRONISM, TEST FACILITIES, WAVEFORMS, AIR FORCE RESEARCH

Subject Categories : Seismology
      Nuclear Weapons

Distribution Statement : APPROVED FOR PUBLIC RELEASE