Elastic Dislocations in a Layered Half-Space?II The Point Source

Abstract

The static displacement and strain fields caused by the introduction of a shear dislocation point source into a layered elastic half space have been evaluated using a Thomson-Haskell matrix method (Singh). The point source was found to be an adequate representation of a fault at distances greater than four fault lengths. Gross earth structure (oceanic, shield and tectonic models) cause fields that differ little from those of a uniform half space. However, significant departures from the uniform half-space fields are found to be caused by low rigidity layers, both at the surface (representing sediment cover) and at depth (representing possible zones of partial melt). Both of these features cause complexities in the strain fields that depend on the source orientation and source-receiver distance, and these may result in amplification or attenuation of the uniform half-space fields by factors of up to 10.