Elastodynamic Event Sequences on Rough Faults

Columbia University, New York NY

Investigators

Abstract

Geometrical and material heterogeneities in faults have long been viewed as a crucial feature affecting earthquake behavior. More recently, the role of stress heterogeneities has begun to be recognized as a potentially central feature, particularly with the demonstration that stress heterogeneities alone already can produce a remarkably rich and complex set of earthquake-like behaviors on uniform planar faults. What is missing is an understanding of how the two types of heterogeneities, the static geometrical and material heterogeneities, and the dynamic stress heterogeneities, might combine and interact to produce even more realistic behavior. This research seeks to further develop a line of modeling which extends elastodynamic simulations to nonplanar geometries. Specifically, the aim is to develop simulations of rough fault geometries. By studying long sequences of events on the faults, the dynamical attractor develops, and thus the interaction of stress heterogeneities with any geometrical heterogeneities can be examined. As well as developing the technology, we are applying the model to a set of observations, including normal stress effects, rupture initiation and termination, and aftershocks. These applications have relevance to understanding friction better, improving long term hazard estimation based on segmentation, and short term hazard estimation based on aftershocks.