Regional Attenuation at PIDC Stations and the Transportability of the S/P Discriminant
Abstract
Frequency-dependent regional-wave amplitudes for nine subnetworks of the pIDC in varying geologic and tectonic environments were inverted for source and attenuation models. These models were used to normalize and evaluate variants of the S/P regional discriminant (e.g., various frequency bands and regional phases) using a data set of earthquakes, presumed industrial explosions, and a few nuclear explosions from the Lop Nor test site. Path and source corrections derived from the models were effective at removing the distance and magnitude dependence of the S/P ratios. Several variants of the normalized S/P ratios were successful at separating nuclear explosions from earthquakes. In particular, low to mid-frequency bands performed best. As expected, nuclear explosions are characterized by lower S/P ratios than earthquakes. However, the average S/P ratios are only slightly lower for industrial explosions than for earthquakes, and there is considerable overlap. Average "stable" and "tectonic" attenuation models were developed that are generally within one standard deviation of the region-specific models. Thus, the models and normalized S/P discriminant appear to be transportable to uncalibrated regions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 31, 1998
- Accession Number
- ADA375481
Entities
People
- Douglas A. Brumbaugh
- Richard D. Jenkins
- Thomas J. Sereno