Transportable Seismic Discriminants
Abstract
This research addresses the issue of discriminant transportability, that is, the development of discriminants which can be applied to events in a variety of geographic areas. The failure of discriminants to work for events in new areas of study is most often attributed to the effects of changes in the propagation path (Q, phase blockage, scattering, focusing (defocusing, etc.). An additional factor is the instability of spectral ratio measurements. The spectra of Pri and Lg waves for small explosions often exhibit spectral nulls due to the time%dayed multiple shots. often these spectral nulls occur at slightly different frequencies, contributing to artificial maxima and nunima ol the LgIPn spectral ratio. In our approach, we deconvolve the source effects separately for Lg and Pri before the spectral ratio is computed. This is accomplished by detrending the array averaged log-spectra and then computing a source time function based on the spectral null% We use both the deconvolved spectral ratio and the derived source time function for event identification. This procedure has been tested on a number of Ground Truth Databases which include events from Scandinavia, central Europe, Spain, and the Middle EasL
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1997
- Accession Number
- ADA353942
Entities
People
- Jay J. Pulli