Numerical simulation of the relationship between the tectonic stress distribution and the historical strong earthquake activities of the middle-southern segment of eastern boundary of the Sichuan-Yunnan block

As the middle-southern segment of eastern boundary of Sichuan-Yunnan block, Anninghe-Zemuhe-Xiaojiang fault zone is very important to understand activities of strong earthquakes on the fault zone. This paper mainly focuses on the tectonic stress and the Coulomb stress caused by the earthquake rupture on the fault zone and their relationship with history strong earthquakes. Using different-size contact pairs to describe the spatial segment characteristic of the fault zone, and using the viscoelastic constitutive relation to discribe the different blocks, this paper establishes a three-dimensional finite-element model of the Anninghe-Zemuhe-Xiaojiang fault zone based on the latest data on crustal structure, seismotectonics, stress field, GPS, and rheology of the lithosphere. Considering the impact of the gravitational potential of the Qinghai-Xizang (Tibet) Plateau and the velocity boundary conditions, the stress distributon of the fault zones is obtained. The results indicate that the distribution of tectonic stress corresponds to activities of the strong earthquakes more obviously. And some places with tectonic stress concentration, such as Shimian, Xichang, Qiaojia, and Dongchuan, may be future seismic hazard areas.