The Xianshuihe fault zone is situated at the eastern margin of the Tibetan Plateau, with a highly active left-lateral strike-slip fault in the late quaternary. In the past few hundred years, there occurred at least eight M ≥7.0 earthquakes, and most distribute along the northwestern segment. In this paper, we employ the three dimensional viscoelastic finite element model of Xianshuihe fault and its surrounding region to explore the relation between fault slip rate and stress field, even the seismic distribution difference, according to the optimal boundary condition. And finally the slip rate pattern in different Young modulus of the fault gauge is discussed.
The preliminarily modeled results show that the slip rate is relatively higher along the northwestern segment of the Xianshuihe fault zone. Meanwhile, the maximum shear stress is mainly located in the fault terminal, intersections and the bend of the fault geometry, the stress level on the northwestern segment that has the high slip rate is relatively high, which may be responsible for the seismic differential distribution. Additionally, with the reduction of the Young's modulus in the fault zone, the fault acts as the detachment layer, and it is conducive to generate the higher slip rate.
The Xianshuihe fault zone is located altha eastern margin of the Tibetan Plateau, which is a highly active left-lateral strike-slip fault in the late quaternary (Fig. 1). The slip rate is 15±5mm/a in the northwestern segment, while the southeastern less than 10mmla, according to geological method (Allen et a1.,1991).1n the past few hundred years, there occurred at least eight M≥7.0 earthquakes, and five distributed along the northwestern segment, the seismic activity expresses the spatial differential distribution (Wen et at., 2008). The previous results suggest that the obstructing effect from the South China block and fault strike difference should be responsible for the difference (Pan et al., 1994; Wang et al., 201 0). However, it remains unclear as how these factors influence the difference in detail.