Conditions for Consecutive Rupture of Adjacent Asperities
Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
Numerical simulation of earthquake cycles is carried out using a three-dimensional infinite uniform elastic model with a planar fault in which frictional stress obeys a rate- and state-dependent law. Two circular asperities with velocity-weakening frictional properties are embedded in a model fault plane, and velocity-strengthening friction is assumed in remaining regions. Different values of the characteristic slip distance L are given to the two asperities so that seismic rupture nucleated at the asperity with smaller L may be arrested at the asperity with larger L. Seismic rupture is arrested in the large L asperity for high contrast in L when shear stress at the large L asperity is low. The condition for rupture arrest is examined using a phase plane plot of frictional stress and slip velocity to show that varying effective stiffness of an asperity is important for consecutive rupture. Effective stiffness of an asperity decreases during an interseismic period due to inward propagation of aseismic sliding.
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