On strike-slip dislocation in an elastic half space in the presence of localized distributions of strain nuclei

Summary The Somigliana dislocation theory is applied to the study of strike-slip faulting in an isotropic, homogeneous, elastic half space in the presence of localized distributions of strain nuclei. Vanishing shear tractions on the dislocation surface are assumed and the slip amplitude as a function of depth is derived, together with the stress drop pattern and the energy release. The results show indications that the condition of continuous stable sliding prevailing at depth along the locked sections of faults may strongly affect the slip, the stress drop and the energy release of a seismic dislocation event. Moreover, fault widths derived from dislocation models driven from underneath are greater than those evaluated from models with a uniform initial stress field and thus tend to explain in simple terms the common finding in some regions that earthquake foci are deeper than evaluated widths of dislocation surfaces.