Dynamic Rupture and Strong Ground Motion Simulations Performed on the Northern and Eastern Boundaries of the Sichuan-Yunnan Block, China

Date: 4/25/2019

Time: 10:45 AM

Room: Elliott Bay

The Sichuan-Yunnan block is one of the most seismicity active regions in China and it give birth to many documented devastating earthquakes in history on its boundaries. In general, the northern and eastern boundaries of this block are more active than the southern and western boundaries. The northern boundary of the Sichuan-Yunnan block mainly consisted of the Ganzi-Yushu fault system and the Xianshuihe fault system, while the Anninghe-Zemuhe fault system and the Xiaojiang fault system are acting as the eastern boundary of the block. Motivated by the potential seismic risk posed to the neighboring residences, we first simulated some typical historical earthquakes using the curved grid finite difference method (CG-FDM), and then we compared the synthetic surface displacement, magnitude and seismic intensity distribution with the documented data to get optimized modeling parameters, such as maximum principle stress azimuth, static friction coefficient μ_s and dynamic coefficient μ_d. After that, we simulated earthquake scenarios on the above boundary with different nucleation points and initial stress states, in order to give a glance at disastrous earthquakes that may happen in the future. Our preliminary simulation results demonstrated that the maximum principle stress orientation along the northern and eastern boundary changes regularly, clockwise from north to south, the effective friction coefficients are similar between different fault systems. The modeling also illustrates that the dynamic rupture propagation is close controlled by the fault geometries. The sharp changes in strike arrest the rupture spontaneously. Future scenario earthquakes show that no matter which the seismogenic fault is, there is possibility of occurring catastrophic event with moment magnitude larger than 7 on that fault.

Presenting Author: Houyun Yu

Authors