Accession Number : ADA319766

Title :   Regional Small-Event Identification Using Seismic Networks and Arrays.

Descriptive Note : Scientific rept. no. 1,

Corporate Author : CALIFORNIA UNIV SAN DIEGO LA JOLLA INST OF GEOPHYSICS AND PLANETARY PHYSICS

Personal Author(s) : Hedlin, Michael ; Vernon, Frank ; Minster, J. B. ; Orcutt, John

PDF Url : ADA319766

Report Date : 15 JUL 1996

Pagination or Media Count : 41

Abstract : The CTBT negotiations have endowed small seismo/acoustic events (mb ^ 2.5) with a much greater significance than they have had in the past and have increased the need for automated regional discrimination. We have been contracted by AFTAC to develop a small event discriminant that uses a time frequency expansion (sonogram) of seismic coda to discriminate ripple fired mining explosions from single explosions and earthquakes. The Automated Time Frequency Discriminant (ATFD) which we have developed uses a binary sonogram which is derived from the original, spectral, sonogram by the application of filters which replace the spectral information with a binary code which simply reflects local spectral highs and lows. We have found that the binary patterns which we extract from the coda of ripple-fired events are banded and thus distinct from those obtained from single explosions and earthquakes. The bands, which result from source finiteness, intershot delays or a combination of the two, are largely independent of time and of the recording component. The ATFD uses three statistical tests to measure the time and recording component independence and automatically recognize these bands. All of the raw discrimination parameters produced by these tests are merged into a single discriminant score with multivariate statistics.

Descriptors :   *SEISMIC DISCRIMINATION, *SEISMIC ARRAYS, TIME DEPENDENCE, NETWORKS, MULTIVARIATE ANALYSIS, STATISTICAL TESTS, EXPLOSIONS, GEOACOUSTICS, EARTHQUAKES, SEISMOLOGICAL STATIONS.

Subject Categories : Seismology
      Seismic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE