Accession Number : ADP204499

Title :   Broadband Signal Enhancement of Seismic Array Data: Application to Long-period Surface Waves and High-frequency Wavefields,

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

Personal Author(s) : Vernon, Frank ; Mellors, Robert ; Thomson, David

PDF Url : ADP204499

Report Date : 14 AUG 1995

Pagination or Media Count : 8

Abstract : We are developing a radically new approach to the problem of low signal-to-noise long-period surface waves using a newly developed approach that Thomson (1990) calls quadratic inverse theory. Analysis of surface wave dispersion requires precise measurements of relative phase. The double coherence estimate provides the the coherence and phase between different frequencies in the same signal. We tested the multitaper double-coherence technique with simple signals. The signals were designed to mimic the characteristics of idealized seismic data (both surface and body waves) but with defined frequency and amplitude. Initially, pure signals were processed and plotted. The signals were then degraded by adding random noise and plotted. We compared the results from the pure signals and the noisy signals to identify robust features in the coherence plots. Tests with real seismic data yield patterns similar to those seen in synthetic tests. We plan to conduct further tests with seismic data and investigate methods to further improve signal resolution.

Descriptors :   *SEISMIC DETECTION, *SEISMIC WAVES, *ARMS CONTROL, *NUCLEAR EXPLOSION DETECTION, *SEISMIC DISCRIMINATION, *EARTHQUAKES, DATA PROCESSING, SYMPOSIA, SURFACE WAVES, VERIFICATION, MONITORING, SIGNAL TO NOISE RATIO, UNDERGROUND EXPLOSIONS, NUCLEAR EXPLOSION TESTING, SEISMIC DATA, BROADBAND, TREATIES, SEISMIC ARRAYS.

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

Distribution Statement : APPROVED FOR PUBLIC RELEASE