Accession Number : ADP204422

Title :   The Portability of Some Regional Seismic Discriminants and Related Broadband Waveform Modeling,

Corporate Author : WOODWARD-CLYDE FEDERAL SERVICES PASADENA CA

Personal Author(s) : Woods, Bradley B. ; Saikia, Chandan K.

PDF Url : ADP204422

Report Date : 14 AUG 1995

Pagination or Media Count : 10

Abstract : We are investigating the portability of regional seismic discriminants which were developed from the analysis of data for southwestern U.S. earthquakes and NTS explosions. Besides determining whether or not these discriminants are effective for seismic events in other tectonically active regions, it will be possible to calibrate the effective discriminant parameters for these different regions, so that an event from any such area can be incorporated into a unified database. Events studied are the U.S. PNE's and earthquakes in the Colorado Plateau/Rockies region, explosions at the Kazaldi (CIS) and Lop Nor (PRC) test sites, as well as earthquakes in and around this region of Asia. Events in Pakistan are analyzed by these discriminants, too, although no explosion data are available. This region includes significant deep seismicity (d>50km). The discriminants being used here are the ratio of integrated short-period P-wave to long-period energy (predominantly surface wave) summed over the three components (sp sub z-P/lp sub 3), the ratio of integrated short-period vertical component energy between the P and S wavetrains (sp sub z-P/sp sub z-S), and the ratio of M sub L to scalar seismic moment (M sub 0). For the Colorado Plateau data set the energy ratio discriminants were modified to use peak amplitudes, as many of the records could not be digitized. The sp sub z-P/lp sub 3 discriminant is most effective at distinguishing source-types. The sp sub z-P/sp sub z-S energy ratio appears to be useful to identify deep events from shallower crustal earthquakes. The M sub L:M sub 0 discriminant is deterministic, requiring Green's functions that reflect the crustal structure of a region with which to invert waveform data to obtain the source parameters for any event.

Descriptors :   *SEISMIC DETECTION, *ARMS CONTROL, *NUCLEAR EXPLOSION DETECTION, *SEISMIC DISCRIMINATION, PAKISTAN, SYMPOSIA, SURFACE WAVES, VERIFICATION, UNDERGROUND EXPLOSIONS, NUCLEAR EXPLOSION TESTING, EARTH CRUST, SEISMIC WAVES, TREATIES, EARTHQUAKES, GREENS FUNCTIONS, AMPLITUDE, ASIA, COLORADO, CIS.

Subject Categories : Government and Political Science
      Seismology
      Seismic Detection and Detectors
      Nuclear Weapons

Distribution Statement : APPROVED FOR PUBLIC RELEASE