3D GEOMETRIC MODELS OF THE HAYWARD FAULT FOR USE IN DISTINCT-ELEMENT MODELS OF BAY AREA DEFORMATION AND SEISMICITY
These fault models are being used to define a realistic HF geometry for use with distinct-element that are currently in development. The distinct-element method treats a rockmass as a bonded - in tension and shear - assembly of frictional, elastic spheres. Loading the boundary of the assembly forces bonds between particles to fail in a progressive manner, very effectively simulating rock fractures, which subsequently link up to form thoroughgoing faults. The geometry of the Hayward fault, which has been constructed from relocated hypocenter locations, is introduced into the particle assembly as an irregular plane of particles that separates the intact blocks on either side of the fault. Fault surface asperities within the models will be sites of stress concentration and resist slip.
This work is based on the hypothesis that fault surface topography is the major factor that determines the location of earthquakes upon pre-existing faults. These models will predict possible locations of future faulting, both strike- and dip-slip.