历史以来，鲜水河-小江-龙门山“Y”形断裂带系破坏性地震频发，该断裂带系的地震活动性与危险性问题是我国地学研究的热点之一。本项目将通过有限元方法数值模拟该断裂带系的应力演化过程，包括：初始应力场、震间构造应力积累、历史地震应力扰动；定量地分析该裂带系的构造应力积累分布状态；重点探讨断层的几何形态与不同部位的耦合程度，对断层的应力积累分布细节的影响；寻找应力时空演化与地震活动性之间的关联及规律，厘清震间构造应力积累与历史地震应力扰动在应力演化过程中的具体贡献，探讨该区域孕震机制，为分析板内地震发生机理提供一定的认识；在此基础上，结合其它地球物理、地质观测资料，如：地应力测量、地热流、居里面深度、和GPS形变数据等，分析该断裂带系的地震危险性，特别“Y”形断裂带系交叉区域与地震空区的地震危险性。其研究结果可以为判定该区域的地震危险性提供必要的约束，为当地的防震减灾工作提供一定的理论依据。

The Xianshuihe-Xiaojiang-Longmenshan fault system is a very seismically active region where devastating earthquakes frequently occurred. This study aims to investigate the seismic activities and hazards in this region from the point view of stress evolution by 3D numerical modelling. On the basis of the high resolution lithospheric structure revealed by seismological investigation, several finite element models are set up with boundary conditions of steady compressional deformation rate constrained by GPS observations. We calculate stress evolution process in the fault system, including the initial stress, the inter-seismic stress accumulation, and stress change induced by the earthquakes in the fault zone and nearby regions. The influence of the stress results by the complicated fault geometry and coupling degree will be fully discussed. On the basis of the stress results the controlling factors of stress heterogeneity on the seismic activities of the fault zone will be analyzed. Combining with the data provided by other geological and geophysical investigation, we analyze the seismic activities of the fault system by demonstrating the stress distribution in the fault system. This research will provide some useful constraints on estimating the seismic hazards, and important information for the earthquake prevention and disaster relief in this area.