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ViscoSim. USGS, Menlo Park. Fred Pollitz. Representation of Fault Friction. Static frictional stress. Dynamic frictional stress. Arrest stress. Dynamic overshoot parameter:. D = ( s s - s a )/( s s - s d ). Stress reduction parameter: Ds = s s - s a.
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ViscoSim USGS, Menlo Park Fred Pollitz
Representation of Fault Friction Static frictional stress Dynamic frictional stress Arrest stress Dynamic overshoot parameter: D = (ss - sa)/(ss - sd) Stress reduction parameter: Ds = ss - sa
Representation of Viscoelasticity h = 3 x1019Pa s h = 1019Pa s
Approximations to Elastodynamics • Representation of inertia • None • Representation of rupture propagation • Cascade model
# Viscoelastic Greens functions = x 3721 [map points] X 16 [source depths] X 16 [obs. depths] x 11 [sample times] x 6 [stress tensor components] =6x 107
Simulator parameters Dynamic overshoot parameter: D = (ss - sa)/(ss - sd) Stress reduction parameter: Ds = ss - sa Shape of slip-weakening curve Mantle viscosity hm
Results with ViscoSim • Fault system behavior is sensitive to simple parameters • Simulations capture Gutenberg-Richter and characteristic-earthquake behavior • Characteristic magnitude and mean recurrence interval may exhibit a systematic dependence on mantle viscosity