3D simulations of multi-segment thrust fault rupture

Abstract

Thrust faults, such as those that underlie the Los Angeles basin, are typically segmented by tear faults that offset the thrust fault segments. We perform 3D finite difference simulations of earthquake rupture to evaluate the effectiveness of these offsets in retarding rupture. The simulations include orthogonal, intersecting faults to model the interaction of the thrust fault segments with the tear fault. For reasonable assumptions for fault segment 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 studied thrust earthquakes. Absent a tear fault, the maximum offset that can be breached is an order of magnitude smaller. Copyright 1999 by the American Geophysical Union.