Elastodynamic Event Sequences on Rough Faults

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Geometrical and material heterogeneities in faults have long been viewed as a crucial feature affecting earthquake behavior. More recently, the role ofstress 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-likebehaviors on uniform planar faults. What is missing is an understanding of howthe two types of heterogeneities, the static geometrical and materialheterogeneities, and the dynamic stress heterogeneities, might combineand 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 attractordevelops, and thus the interaction of stress heterogeneities with anygeometrical heterogeneities can be examined. As well as developing the technology, we are applying the modelto a set of observations, including normal stress effects, ruptureinitiation and termination, and aftershocks. These applicationshave relevance to understanding friction better, improving long term hazard estimation based on segmentation, and short term hazard estimationbased on aftershocks.