Abstract
The Partial differential equation, which represents approximately the propagation of a crack, obtained by YAMASHITA (1976) is solved numerically, and the dependence on the tectonic field of the source parameters is studied in detail. Main results are as follows:
The importance of effective stress and the fracture strength distribution for the dynamical process of fault motion is ascertained from the numerical computation and in the interpretation of observed data. The proportional relation between effective stress and dislocation velocity exists, but the ratio is widely different from BRUNE'S (1970) result. Effective stress is linearly proportional to stress drop. When initial stress fields are represented by a pair of linear functions and a quadratic function of the distance in the direction of dislocation surface, the approximate relations σeff≅10Δσ andσeff≅6Δσ hold respectively. Initial stress field of a Japanese inland earthquake is approximated by a pair of linear functions with small slopes. That of an earthquake along the trench is approximated by a quadratic function with a firly large coefficient. The dislocation velocity is in direct proportion to the stress drop.
