We attempt to develop a physical basis for earthquake dynamics and seismic hazard on large strike-slip faults by joint analysis of model realizations, with parameters representing specific fault zones, and multidisciplinary observations of deformation phenomena. The model consists of discrete slip patches (representing structural segmentation) on a vertical plane in a 3-D solid, and it accounts for brittle slip, creep slip, realistic boundary conditions, and 3-D elastic stress transfer. Recent developments extended the framework to incorporate quasidynamic rupture propagation, gradual healing, and creeping barriers along the fault.
We show that the model produces realistic frequency-size and
temporal statistics of earthquakes, hypocenter distributions,
foreshock-mainshock-aftershock sequences, slip histories, approach
to and retreat from criticality, and accelerating seismic release.
Systematic analytical and numerical parameter-space studies
indicate the existence of basic dynamic regimes. The first is
associated with strong fault heterogeneities, power law
frequency-size statistics of earthquakes, and random or clustered
temporal statistics of intermediate and large events. The second
is associated with homogeneous or relatively regular faults,
peaked frequency-size statistics (compatible with the
characteristic earthquake distribution), and quasi-periodic
temporal occurrence of large events. For a range of parameters,
there is a third regime in which the response switches back and
forth between the forgoing two modes of behavior. The results can
be understood in terms of the phase diagram technique and the
concept of intermittent criticality.
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