Three-dimensional earthquake cycle simulation on subduction planes with rate- and state-dependent friction

What control dynamic rupture propagation of megathrust earthquakes? How do different sizes of earthquakes on a subduction plane interact with one another? How may various slow slip behaviors be related to megathrust earthquakes? These questions may be addressed by earthquake cycle modeling that fully captures both the co-seismic dynamic process and other quasi-static processes. However, existing earthquake simulators in the community either significantly simplify the co-seismic process or are limited to simple vertical strike-slip faults. In this study, we develop an earthquake cycle simulator for subduction planes with rate- and state- dependent friction that fully capture all stages of an earthquake cycle. This earthquake simulator bases on our explicit, dynamic finite element method code EQdyna. EQdyna is developed to simulate spontaneous rupture propagation on geometrically complex faults and seismic wave propagation in complex geologic media. To simulate other quasi-static processes of an earthquake cycle, including the nucleation, post-seismic, and inter-seismic phases, we make use of the dynamic relaxation technique, which allows us to use EQdyna to obtain solutions for these quasi-static processes. Our preliminary results suggest that this newly developed earthquake simulator successfully reproduces all four major phases of an earthquake cycle on a thrust fault, with major characteristics including stable sliding during interseismic phase, smooth but rapid growth of slip velocity during the nucleation phase, spontaneous rupture propagation during the coseismic phase, and gradual decay of slip velocity during the post-seismic phase. With all stages of an earthquake cycle captured, multiple cycle simulations will allow us to address the above questions from a physical point of view, in conjunction with available observations at subduction zones.