Accession Number : ADP204406

Title :   Cross Region Analysis, Path Corrections and the Transportability of Regional Seismic Discriminants,

Corporate Author : ENSCO INC SPRINGFIELD VA

Personal Author(s) : Baumgardt, Douglas R.

PDF Url : ADP204406

Report Date : 14 AUG 1995

Pagination or Media Count : 9

Abstract : This study has investigated the problem of transporting regional discriminants, principally the regional P/S amplitude ratio and Lg spectral discriminants, between regions of differing tectonic type. The effects of differential regional phase attenuation and propagation blockages need to be taken into account and corrected before decision criteria for discriminants developed in one tectonic region can be transported to a different tectonic region. We have developed a set of frequency-dependent distance correction curves to correct the Pn/Sn and Pn/Lg amplitude ratio to a standard distance. Similar corrections have been developed for the Lg spectral ratio using a standard Lg attenuation model. Also, we have developed a method, called cross-region seismic event characterization, to characterize and identify new events which occur in aseismic regions or regions lacking known source types. Discrimination processing results of the Intelligent Seismic Event Identification System (ISEIS) for many different regions are stored in an Oracle database and can be called up on a regionalized basis. When a new event occurs, the method of cross-region seismic event characterization tries to find reference events from different regions, probably recorded at different stations than the new event, but at comparable distance for comparison which can be used as reference or training events to identify the new event. We construct crustal cross sections for the different propagation paths and determine if the new event has similar cross sections as the reference events. If the paths are not too different, the discriminants can be directly compared, after correcting for differences in distance.

Descriptors :   *ARMS CONTROL, *NUCLEAR EXPLOSION DETECTION, *SEISMIC DISCRIMINATION, *EARTHQUAKES, *TECTONICS, DATA BASES, SYMPOSIA, NUCLEAR EXPLOSION TESTING, MINING ENGINEERING, SEISMIC DATA, WAVE PROPAGATION, EARTH CRUST, SEISMIC WAVES, ATTENUATION, RUSSIA, TREATIES, SEISMIC VELOCITY, SEISMOLOGY, CHINA, SEISMIC ARRAYS, ASEISMIC AREAS.

Subject Categories : Government and Political Science
      Geology, Geochemistry and Mineralogy
      Seismology
      Seismic Detection and Detectors
      Nuclear Weapons

Distribution Statement : APPROVED FOR PUBLIC RELEASE