Dynamic and static interaction of two thrust faults: A case study with general implications

Abstract

We use a dynamic analysis (the 3‐D finite element method) to study the dynamic and static interactions between segments in a system of two thrust faults. The simulated fault geometry is modeled after a specific fault system in central California. However, we find that by varying both the degree of segment overlap along strike and the stress heterogeneity, we arrive at results that may have broader implications for the dynamics of interacting fault segments. We find that the degree of dynamic interaction between fault segments depends strongly on the overlap between the segments and the heterogeneity of stress. In some cases, a static analysis predicts the aspects of dynamic behavior of the fault system, including rupture jumping from one segment to the other. In other cases, there is a complex two‐way interaction between the fault segments, which can only be captured by a full three‐dimensional dynamic analysis. The results show the limitations of a static analysis for predicting the behavior of geometrically complex fault systems and the importance of dynamic stress waves in mediating the interaction between nearby fault segments. The results also help to shed light on the mechanism by which rupture terminates on some segments and jumps to others.