MODELING OF RUPTURE PROPAGATION ALONG AN ACTIVE FAULT WITH HETEROGENEOUS FRICTION

Abstract

The analysis of geological information indicates the presence in the fault zone of segments radically different in structure, material composition and, as a result, frictional characteristics. In this work, on the basis of numerical calculations, we consider the role of regions with different properties during the development of a dynamic fault initiated in the area of a heterogeneous tectonic fault. It is shown that the characteristic size of frictional inhomogeneities on the slip plane and the density of their arrangement largely determine the features of the fracture propagation, including such poorly studied stages as its start and stop. The initiation of a rupture of a local area can be caused by various reasons – a change in pore pressure, the impact of seismic vibrations from remote events, and intergeospheric interactions. After initiation on one of the «locked» segments, a dynamic fracture can propagate even at a relatively small level of shear stresses compared to the peak contact strength. The condition for this is the presence on the fault plane of other contact regions with properties of frictional weakening. In this case, it turns out to be necessary to ensure the conditions of initiation only in a local area, and then the dynamic shear can be maintained by a stress wave radiated from the surface of a propagating discontinuity.