Accession Number : ADP204462

Title :   Making Accurate Continental Broadband Surface Wave Measurements,

Corporate Author : COLORADO UNIV AT BOULDER DEPT OF PHYSICS

Personal Author(s) : Ritzwoller, M. H. ; Levshin, A. L. ; Smith, S. S. ; Lee, C. S.

PDF Url : ADP204462

Report Date : 14 AUG 1995

Pagination or Media Count : 9

Abstract : Described herein are methods designed to obtain accurate broadband surface wave dispersion measurements on two spatial/frequency 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 GSN/CDSN/GEOSCOPE/MEDNET 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 KNET's 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.

Descriptors :   *SURFACE WAVES, *SEISMIC DETECTION, *ARMS CONTROL, *NUCLEAR EXPLOSION DETECTION, SYMPOSIA, MONITORING, UNDERGROUND EXPLOSIONS, NUCLEAR EXPLOSION TESTING, BROADBAND, EARTH CRUST, HETEROGENEITY, SEISMIC DISCRIMINATION, TREATIES, AMPLITUDE, SEISMIC VELOCITY, EURASIA, ASIA, RAYLEIGH WAVES, EARTH MANTLE, LOVE WAVES, TELEMETER SYSTEMS, PHASE VELOCITY.

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

Distribution Statement : APPROVED FOR PUBLIC RELEASE