Continuum distribution of dislocations on faults with finite friction

An analysis is made of continuous distributions of infinitesimal dislocations on faults with finite friction. The analysis was undertaken in an attempt to explain the fact that dislocations produced by earthquakes commonly lie at depths that are shallower than the average depth of earthquake foci in continents. (The depths of dislocations are determined from displacements around faults.) It is found that this discrepancy can be explained if, at some depth, there exists a region where the frictional stress on faults is anomalously low.