Fault slip rates in southern California predicted by geodetically constrained non-block viscoelastic model

Monday, 15 December 2014
Ray Y Chuang, Indiana University Bloomington, Bloomington, IN, United States and Kaj M Johnson, Indiana University, Bloomington, IN, United States
We develop mechanical models of present-day surface motions in which deformation is a response to plate boundary forces, gravitational loading, and rheological properties of the lithosphere and active fault interfaces. To model fault-slip rates in southern California, we populate an elastic-visco thin sheet (plane stress) with viscous shear zones (faults) and impose far-field stress tensor and gravitational loading to compute the long-term fault slip rates and crustal motions. The mechanical models inherently allow slips along through-going and discontinuous faults and the viscosity of the lithospheric sheet relaxes unreasonable stress build-up. The models predict long-term fault-slip rates in southern California and incorporate backslip as interseismic deformation due to locking of faults to compare the total present-day deformation field (long-term plus intersesismic) with the GPS-derived velocity field.