Accession Number:

ADP204499

Title:

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

Descriptive Note:

Corporate Author:

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

Report Date:

1995-08-14

Pagination or Media Count:

8.0

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.

Subject Categories:

  • Government and Political Science
  • Seismology
  • Seismic Detection and Detectors
  • Nuclear Weapons
  • Computer Programming and Software

Distribution Statement:

APPROVED FOR PUBLIC RELEASE