Dynamic Rupture Simulations Performed on the Northern and Eastern Boundary Faults of the Sichuan-Yunnan block, China

As one of the most seismicity active regions in China, the Sichuan-Yunnan block has been giving birth to lots of damaging earthquakes on its boundaries since its existence. In general, the northern and eastern boundary faults of this block are more active than the southern and western boundary faults. The northern boundary faults of this block can be listed as the Ganzi-Yushu fault and the Xianshuihe fault, while the eastern boundary faults mainly consisted of the Anninghe-Zemuhe fault and the Xiaojiang fault. Devastating earthquakes with magnitude great than or equal to 7 have occurred in all these faults in history. Motivated by the potential seismic hazard posed to the nearby regions, we first simulate some representative historical earthquakes on the above boundary faults using the curved grid finite difference method (CG-FDM), and then we obtain the optimized modeling parameters, such as maximum principle stress azimuth, friction coefficients μ_s and μ_d, through comparing the documented surface displacements, magnitude and seismic intensity distribution with the synthetic data. After that, we simulate potential earthquake scenarios on the above boundary faults with previous preferred simulation parameters to give a glance at destructive earthquakes that may happen in the future. The preliminary simulation results presented that the maximum principle stress orientation along the northern and eastern boundary rotates clockwisely from north to south, and the effective friction coefficients are similar between different fault systems. Some of the simulations also indicated that the dynamic rupture propagation is closely controlled by the fault geometry. The sharp change in strike along the fault can arrests the rupture spontaneously. Future potential earthquake scenarios showed that all the mentioned boundary faults have the possibility to occurring devastating event with moment magnitude larger than 7.