Broadband Discrimination Studies
Abstract
A seismic array consisting of 9 stations arranged as three nested triangles with minimum spacing of 100 m and maximum spacing of 400 m was used to record the two NTS explosions, LIPTAUER in Yucca Valley on 3 April 1980 and COLWICK on Pahute Mesa on 26 April 1980. The distance of the array from the explosion was 1.9 km for LIPTAUER and 6.0 km for COLWICK. So far our analysis has concentrated on the COLWICK data. Preliminary results show that most of the energy in the first 5 sec of the seismograms is propagating at an azimuth and velocity which are consistent with generation at or very near the explosive sourcel The spatial coherence decays by a factor of 1/e at distances that range between 400 and 1200 m, depending upon direction and component of motion. In a direction parallel to the wavefront, the vertical and radial components are much more coherent than the transverse component, while all of the components have comparable coherence in a direction perpendicular to the wavefront. Coherence generally decreases as frequency increases. In addition to aiding our interpretation of elastic waves generated by an explosion, these array data should provide useful constraints on the possible mechanisms by which elastic waves can be scattered by inhomogeneities near the surface of the earth.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 29, 1980
- Accession Number
- ADA222133
Entities
People
- L. R. Johnson
- Thomas V. McEvilly
Organizations
- University of California, Berkeley