Static deformation of a laterally inhomogeneous half-space by a two-dimensional strike-slip fault

Abstract

On the basis of the elastic dislocation theory, formulas are derived for the displacement, strain and stress fields of an arbitrarily situated, twodimensional strike-slip fault in a laterally inhomogeneous medium. It is assumed that the elastic half-space is made up of n+l isotropic and homogeneous media being in welded contact and separated by n vertical interfaces. The explicit expressions of coefficients which appear in the formulas are listed for the case n=2. They are checked with the previous results obtained with the help of the method of images. As an application of the formulas derived, the surface displacement field of a vertical strike-slip fault is determined. Three different models are analyzed on the basis of the data concerning medium structure along a section of the San-Andreas fault near Bear Valley. In the presence of lateral inhomogeneities of the medium, it is shown that the elastic field of an earthquake should exhibit distinct asymmetry. This conclusion is confirmed by the existing geodetic data. In particular, the Tango earthquake of 1927 is discussed in greater detail. © 1978, The Seismological Society of Japan, The Volcanological Society of Japan, The Geodetic Society of Japan. All rights reserved.