TWO-DIMENSIONAL RUPTURE PROPAGATION CONTROLLED BY IRWIN'S CRITERION

Abstract

Spontaneous propagation of an anti-plane shear crack is studied using Irwin's fracture criterion. We obtain the numerical solution of crack tip loci and slip motion when the critical stress intensity factor K_c and the dynamic stress drop Δσ^d are non-uniformly distributed on a fault plane. When rupture prop-agates along a fault plane with a localized high K_c region, the rupture process is divided into three stages. In the first stage, the rupture smoothly propagates with the radiation of elastic waves. In the second stage, when the rupture front reaches the high K_c region, the slip motion is decelerated and the radiated elastic wave is weakened. In the third stage, after the crack tip passes the high K_c region, the slip motion is accelerated again and the intensity of radiated wave increases. This gives a possible interpretation of multiple shock events. In Irwin's criterion, the rupture cannot propagate beyond the high K_c region leaving behind an unbroken area. The rupture process controlled by Griffith's fracture criterion is also studied. The rupture process in Griffith's criterion is similar to that in Irwin's criterion, except that the rupture velocity and the radiated seismic wave energy are somewhat greater than the case of Irwin's criterion.