3D simulations of multi-segment thrust fault rupture

Thrust faults, such as those that underlie the Los Angeles basin, are typic ally segmented by tear faults that offset the thrust fault segments. We per form 3D finite difference simulations of earthquake rupture to evaluate the effectiveness of these offsets in retarding rupture. The simulations inclu de orthogonal, intersecting faults to model the interaction of the thrust f ault segments with the tear fault. For reasonable assumptions for fault seg ment length, strength, and stress drop, rupture can jump offsets of up to 2 km if a tear fault is present, consistent with observations of well studie d thrust earthquakes. Absent a tear fault, the maximum offset that can be b reached is an order of magnitude smaller.