Accession Number:

ADP204462

Title:

Making Accurate Continental Broadband Surface Wave Measurements,

Descriptive Note:

Corporate Author:

COLORADO UNIV AT BOULDER DEPT OF PHYSICS

Report Date:

1995-08-14

Pagination or Media Count:

9.0

Abstract:

Described herein are methods designed to obtain accurate broadband surface wave dispersion measurements on two spatialfrequency scales continent-wide Eurasia 20 - 300 s and regional Central Asia, within 20 deg of KNET 5 - 50 s. These methods are based on well developed frequency-time and floating-filter analyses, and are included within procedures that utilize relational parametric and waveform database structures with rapid graphics, which allow measurements to be made quickly on relatively large volumes of data from a variety of source regions recorded on heterogeneous networks. These methods are currently being applied systematically to GSNCDSNGEOSCOPEMEDNET data and Kyrghyz Telemetered Seismic Network KNET data to yield Rayleigh and Love wave group velocity, phase velocity, polarization, and amplitude measurements. The complexity of Eurasian structure implies that the crucial problem is to extract the desired signals, related to nearly directly arriving waves that can be interpreted deterministically, from the essentially stochastic interfering multipaths and coda. Continent-wide, 200 events have been processed yielding dispersion measurements for more than 3000 paths to date Levshin et aL, 1995. Regionally, data from KNETs continuous channels have been accumulated for future analysis. All waveform including cleaned waveforms and parametric data including dispersion measurements and irequency-time images are stored in CSS v. 3.0 with appropriate extensions. In the near future, experiments will be performed to automate this method, which currently depends critically on human interaction. The resulting measurements and cleaned waveforms will be used.

Subject Categories:

  • Government and Political Science
  • Seismology
  • Seismic Detection and Detectors
  • Nuclear Weapons
  • Geology, Geochemistry and Mineralogy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE