Numerical Simulation of Earthquake Dynamic Rupture along Curved/ Branched fault Segments

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We have conducted simulations of earthquake dynamic rupture on non-planar faults using boundary integral equation method. We found that in the simulation, fault geometry, shear stress applied on the fault and fault constitutive relation are important for the computation of dynamic rupture. Based on these information, we computed the dynamic ruptures of the 2000 western Tottori earthquake, 1891 Nobi earthquake, and 1995 Kobe earthquake. For the western Tottori earthquake, assuming the preexisting fault geometry and uniform constitutive relation, we estimated the stress field around the fault, which was found to be consistent with that estimated by the stress tensor inversion. For the Nobi earthquake there has been a debate whether the buried fault slipped during the earthquake or not. To accelerate the discussion, we conducted a dynamic rupture simulation using the preexisting fault geometry and found that whether or not the buried fault slipped depends on the connectivity to the adjacent fault. Finally, we investigated the Kobe earthquake. Using the fault geometry obtained, the rupture could not propagate bi-laterally. We found that to make a bi-lateral rupture, a small strike slip fault is required just beneath the Akashi trout, which was required by the inversion analysis with GPS data at Akashi bridge. In addition, using the near-fault seismograms observed at the western Tottori earthquake and the 2002 Denali, Alaska earthquake, we showed that the slip-weakening distance is size dependent.We organized two special sessions in 2004 and 2005 American Geophysical Union Fall Meeting. And we had more than 150 abstracts in total for these sessions. We recognized that this is one of the high-lighted topics that many people are interested in. We are now preparing a book to publish the major issues in the sessions.