Strain field in a semi-infinite medium due to an inclined rectangular fault

Abstract

Analytical expressions are derived for the strain fields at an arbitrary depth due to an inclined fault in a semi-infinite medium. These expressions, being composed of elementary functions, are suitable for numerical computations. Basing upon these expressions, we develop a computer program, by which contour maps of deformation fields can be drawn in an arbitrary area designated by input parameters. Using this program, several examples of the strain fields in a semi-infinite medium are shown. Effect of the free surface is clarified by comparing patterns for a semi-infinite medium with those for an infinite medium. For example, in the vertical cross sections, this effect yields saddle points and concentration of contour lines and also the “reverse area”, where sense of the deformation is opposite to that for the case of an infinite medium. The reverse area appears clearly in the shear strain components given by differentiating horizontal displacements with respect to depth. © 1979, The Seismological Society of Japan, The Volcanological Society of Japan, The Geodetic Society of Japan. All rights reserved.