Accession Number : ADA323147
Title : Investigations of Regional Phase Spectral Ratios: Transportability and Measurement Algorithms.
Descriptive Note : Scientific rept. no. 1,
Corporate Author : MAXWELL TECHNOLOGIES INC SAN DIEGO CA
Personal Author(s) : Bennett, Theron J. ; Marshall, Margaret E. ; Barker, Brian W. ; Murphy, John R.
PDF Url : ADA323147
Report Date : OCT 1996
Pagination or Media Count : 72
Abstract : Use of regional phase spectral ratios as discriminants involves parameterization of differences in the relative spectral shape of regional phase signals from different source types. This research program has been directed at improved understanding of the influences of source excitation and propagation on the transportability of regional phase spectral ratio discriminants. For use in these investigations, high quality digital waveform data from regional seismic stations have been compiled for underground nuclear explosions and comparable earthquakes in the western U.S. and Eurasia. We have used some simple bandpass filter algorithms to extract consistent signal spectra and spectral ratios for group velocity windows associated with individual regional phases. Effects of source size and group velocity windows have been analyzed for selected event samples. In the western U.S. our observations indicate Lg and Pg spectral ratio differences between nuclear explosions and earthquakes; but these are diminished when source size differences are taken into account. Similar measurements for Eurasian events show only small differences between source types; and, if source scaling is applied, trends in the spectral ratios for explosions and earthquakes may be opposite to those seen in the western U.S.
Descriptors : *NUCLEAR EXPLOSION DETECTION, *SEISMIC DISCRIMINATION, ALGORITHMS, MONITORING, UNDERGROUND EXPLOSIONS, GROUP VELOCITY, MATHEMATICAL FILTERS, SCALING FACTOR, SPECTRUM ANALYSIS, BANDPASS FILTERS.
Subject Categories : Seismic Detection and Detectors
Distribution Statement : APPROVED FOR PUBLIC RELEASE