Deterministic Methods of Seismic Source Identification
Abstract
In order to interpret seismic event discrimination in terms of the physical properties of the source and to be able to establish new discrimination techniques we have generalized seismic source models based on relaxation source theory to include the effects of non-homogeneous initial prestress. In particular we have considered the effects of strongly concentrated prestress in the vicinity of the shatter zone produced by an explosion. The important result from the work so far completed are: (1) the spectra of P and S waves radiated due to stress relaxation effects can be strongly peaked, with the nature of the peaking being azimuthally dependent in general and quite strongly dependent on the size and location of the initial stress concentration; (2) the corners or peak frequencies of the P and S wave radiation are different from one another (S lower) and are both shifted to higher frequencies when the stress concentration is close to the shatter zone. In addition, the corner or peak frequency value is related to the size of the stress concentration rather than to the size of the shatter zone; (3) the pattern of first motions from the tectonic release, when the prestress is inhomogeneous, is not pure quadrupole with higher order multiples also involved. The ordinary quadrupolar pattern predicted from a homogeneous prestress can be strongly distorted when the prestress is concentrated and can be highly non-quadrupole in form.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1979
- Accession Number
- ADA088123
Entities
People
- C. B. Archambeau
Organizations
- University of Colorado Boulder