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Epistemic uncertainty in California-wide simulations of synthetic seismicity. Fred Pollitz, USGS Menlo Park. Acknowledgments: David Schwartz, Steve Ward. Ward (2000). Rundle et al. (2008). Capabilities of this simulator. Inherently discrete fault zone (Ben-Zion and Rice model)
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Epistemic uncertainty in California-wide simulations of synthetic seismicity Fred Pollitz, USGS Menlo Park Acknowledgments: David Schwartz, Steve Ward
Capabilities of this simulator
Inherently discrete fault zone (Ben-Zion and Rice model) • Homogeneous, planar faults • Viscoelasticity of lower crust/upper mantle --> loading through backslip in the fully relaxed limit
Fault network and • slip rates courtesy of • Steve Ward (June, 2009) • Original set of ~4 x 3 km2 • patches are re-grouped • and subdivided into set • of smoothly-connected, • non-overlapping • ~1 x 1 km2 patches • 101208 fault patches
Stress history on a single fault patch Static frictional stress Dynamic frictional stress Arrest stress Dynamic overshoot parameter: D = (ss - sa)/(ss - sd) Stress reduction parameter: Ds = ss - sa
Simulator parameters Dynamic overshoot parameter: D = (ss - sa)/(ss - sd) Stress reduction parameter: Ds = ss - sa Shape of slip-weakening curve Mantle viscosity hm
Simulator results • mean recurrence interval (for given magnitude threshold) • magnitude-frequency statistics, e.g. b-value • coefficient of variation • conditional rupture probability
With slip weakening D=1.25 hm= 1.2 x 1019 Pa s log10 [earthquake production rate (yr-1)] magnitude
With slip weakening D=1.25 hm= 1.2 x 1019 Pa s