川滇地块东边界中南段构造应力分布特征与历史强震活动关系的数值模拟

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

本文以构造应力场观测结果、岩石圈流变特性为约束,采用摩擦接触单元反映断裂带空间分段特征,以最接近真实地下环境的非线性黏弹性材料为模型的本构关系,建立包括安宁河—则木河—小江断裂带的三维有限元模型,模拟在速度边界条件和重力势能等动力因素共同作用下的断裂带应力分布特性.研究结果表明,模拟得到的断裂带现今构造应力场与地震活动有明显的对应关系,应力比较集中的区域,如石棉、西昌、巧家、东川附近,极有可能是未来的地震危险区域.

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.