Seismic wave radiation, propagation and event location in laterally heterogeneous media. Final report, 1 July 1993-31 December 1994

Abstract : Three studies related to nuclear monitoring and discrimination are reported. First, we present a new approach to modeling elastic wave scattering, based on multiple multipole Expansions. Numerical examples demonstrate that the new algorithm is a very general tool for solving relatively large and complex two dimensional scattering. problems. Second, we apply relative event location and waveform cross-correlation techniques to relocate four presumed nuclear explosions at the Balapan, Kazakhstan Test Site. The relative locations obtained from differential P and PoP arrival times at a small number of far-regional and teleseismic stations are more accurate than conventional seismic locations obtained with hundreds of arrival time picks. The third study addresses the effects of non-sphericity of an explosion cavity on seismic wave radiation. A new analytical technique is presented for computing the effects of cavities of arbitrary shape. The technique is applied to study far-field P and S wave radiation from explosions as a function of frequency.