Accession Number : ADA316168

Title :   Effect of 3-D Heterogeneities and Topography on Seismic Wave Propagation and the Use of Empirical Green's Functions for Source Characterization and Discrimination.

Descriptive Note : Final technical rept. 15 May 94-14 May 96,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES

Personal Author(s) : Bouchon, Michel ; Cheng, Ningya ; Imhof, Matthias G. ; Li, Yingping ; Rodi, William L.

PDF Url : ADA316168

Report Date : 01 SEP 1996

Pagination or Media Count : 174

Abstract : 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 techniques. Additionally, finite difference modeling is applied to a comparison of 2-D and 3-D scattering from irregular interfaces. The second topic area is the development of improved seismic discriminants. We find that the empirical Green's function method is effective for estimating the source time functions of earthquakes and explosions, and that the duration of the source time function is a good discriminant for large and very small events. For small events (M<3) and near regional distances (<250 km), Lg spectral ratio is a good discriminant between earthquakes and industrial explosions.

Descriptors :   *SEISMIC WAVES, *SEISMIC DISCRIMINATION, MATHEMATICAL MODELS, ALGORITHMS, NUCLEAR EXPLOSIONS, TIME DEPENDENCE, FINITE ELEMENT ANALYSIS, GROUND SHOCK, GROUND MOTION, THREE DIMENSIONAL, FINITE DIFFERENCE THEORY, SEISMIC DATA, WAVE PROPAGATION, BOUNDARY VALUE PROBLEMS, PARTIAL DIFFERENTIAL EQUATIONS, SYSTEMS ANALYSIS, EARTH SURFACE, EARTHQUAKES, EARTH MODELS, ACOUSTIC SCATTERING, GREENS FUNCTIONS, INTEGRAL EQUATIONS, PRIMARY WAVES(SEISMIC WAVES), RAYLEIGH WAVES.

Subject Categories : Seismology

Distribution Statement : APPROVED FOR PUBLIC RELEASE