2003 Volume 56 Issue 1 Pages 1-9
It has been shown in recent theoretical or numerical studies that nucleation, propagation and termination of earthquake rupture growth are affected by non-planar geometry of fault system, such as bending, branching and stepping. However, most of these studies have assumed a pre-existing fault system and the formation process of the fault system has not been considered. While the formation of fault system is studied in some of recent studies, they have two important limitations: (1) quasi-static deformation is assumed when interacting faults are considered, (2) an isolated fault is assumed when dynamic deformation is treated. We overcome these limitations and investigate a dynamic formation process of a non-planar fault system. We first develop a numerical method, which can treat dynamic interactions between non-planar fault segments, and then simulate a dynamic growth of two interacting faults. We show that resulting fault geometry significantly depends on initial arrangement of the faults and rupture velocity. The two faults coalesce or repel each other according to the initial fault distribution; the two faults are assumed to be of the same size and parallel at an initial state. We find the following important simulation results. The coalescence occurs when two non-coplanar faults are non-overlapped, or partly overlapped, and a strike slip offset, d2, is much smaller than an initial length of the faults. On the contrary, the two faults tend to repel each other when d2 is larger than the initial length of the faults. Our simulation suggests that large earthquakes tend to occur with evolutions of a fault system when the strike slip offset of the fault system is much smaller than the lengths of the segments.
