Deterministic Methods of Seismic Source Identification
Abstract
In this report we describe methods of modal synthesis which provide very detailed theoretical seismograms in the near and regional distance ranges. We give the mathematical basis for the method, along with some examples of its use. We also describe a sophisticated automatic signal analysis program, which is to be used to generate discrimination variables from observed data. The program and underlying procedures were tested using synthetic seismic signals in order to evaluate its performance in the presence of interfering noise. The signal analysis program was also applied to observed seismic data. The purpose of this program is to isolate particular, important, seismic phases (discrete signals) and to obtain accurate estimates of the spectral characteristics of these signals for purposes of event discrimination. Based on its performance, on a variety of observed and synthetic seismic data, it appears that the method can provide much enhanced discrimination/event identification capability, over currently used methods. Finally we illustrate, and discuss, the use of theoretical event magnitude data (m sub b and M sub s) as a basis for event identification. In particular we show that, based on theoretical m sub b versus M sub s relations obtained by synthesizing seismic wave fields in the teleseismic distance range, we can obtain good estimates of seismic source parameters, in particular stress changes and failure zone dimensions for earthquakes and effective stress and nonlinear zone dimensions for explosions, and can use these parameters to form a discrimination available which can serve as a very effective means of discriminating underground explosions from earthquakes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 20, 1981
- Accession Number
- ADA102333
Entities
People
- C. B. Archambeau