Theoretical Models of Earthquake Phenomena and the Physical Significance of Seismic Moment Tensor Expansions
Abstract
The objective of this study is to formulate a physically sound analytical representation of the seismic radiation field produced by spontaneous failure in an arbitrarily prestressed solid. Such formulations, usually given in terms of a Green's function integral equation, may then be expanded in a moment series which is used as a basis of interpretation of observed seismic wave fields from naturally occuring earthquakes. Consequently, a meaningful understanding of the physics involved in such an event, as can be gained from an inversion of observed seismic wave fields, as well as the ability to provide reliable predictions of the seismic radiation to be expected from such events, is dependent on the completeness and accuracy with which the basic integral equation (or numerically based formulation) represents the conservation laws involved in both the failure process and the energy release associated with the seismic radiation. The present study develops an approach that incorporates the (nonlinear) conservation relations on the failure surface, as well as those appropriate in the surrounding linear zone, to generate a Greens function integral equation describing both the failure growth and the (interacting) seismic radiation field. The method involves the explicit decomposition of total stress-displacement fields into dynamic and equilibrium parts, with the latter dependent on time because of the growth of a new boundary corresponding to the failure zone boundary within the prestressed medium; with this boundary growth necessitating a time dependent readjustment of the prestress state to maintain equilibrium.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1989
- Accession Number
- ADA213813
Entities
People
- Charles B. Archambeau
- John Scales