Three-dimensional earthquake cycle simulation on a rate- and state-dependent non-planar subduction plane

The 2011 Tohoku-Oki earthquake (Mw 9.0) has revealed to the science community the potential of the Japan Trench subduction zone in hosting extremely large earthquakes that have not been anticipated before. Combined with the Jogan earthquake that possibly occurred in the year 869 with the similar magnitude and location inferred from tsunami records [Minoura et al., 2001], these giant events are likely to be part of a supercycle of M9-class earthquake sequences spanning over hundreds or even thousands of years. One of the possible reasons that give rise to such long interseismic intervals and large magnitudes of these events is the geometrical complexity of the subduction fault plane. Our preliminary results of spontaneous dynamic simulation on a subduction fault plane with a presumed subducted seamount pre-stressed by assuming certain on-fault slip equivalent to interseismic creeping over one thousand years suggest that the compressional side of the seamount could accumulate an amount of normal stress significantly higher than the background level, resulting in a great hazard capable of generating M9-class earthquakes once triggered. To study more details about the pre-stressing process and characteristics of earthquake cycle on a rate- and state-dependent non-planar thrust fault system, we carry out complete earthquake cycle simulation using finite element method to simulate both the dynamic process (coseismic phase) and the quasi-static aseismic processes (interseismic, nucleation and postseismic phases). With all phases of an earthquake cycle captured, we track the evolution of stress and slip to understand the role of geometrical complexity and other physical factors in generating giant earthquake supercycles.