广州地区活动断裂的数值模拟

NUMERICAL SIMULATION OF ACTIVE FAULTS IN GUANGZHOU AREA

根据广州地区地震地质、地球物理、震源机制解以及GPS观测等相关资料,用三维有限元模型,模拟计算了广州地区4条断裂的现今活动方式以及库仑破裂应力年累积速率。数值模拟结果显示:广州-从化断裂活动方式为压性逆冲;瘦狗岭断裂西段为右旋走滑,东段以右旋走滑为主兼逆冲;珠江口断裂西支和东支活动方式均以左旋走滑为主兼逆冲。广州-从化断裂和瘦狗岭断裂东段断裂面上的库仑破裂应力年累积速率明显高于瘦狗岭断裂西段和珠江口断裂西支、东支。数值模拟计算结果与该地区地震活动特征相一致。

On the basis of the related data of seismogeology, geophysics, focal mechanism solutions and GPS a 3D finite element model of active faults in Guangzhou area was built up to simulate recent the motion mode and the Coulomb rupture stress rate p.a. of four active faults in Guangzhou area under the given boundary condition . The computed results are as follows ： the motion modes of the south and the north segments of Guangzhou-Conghua fault are both compressive thrust;the motion mode of the west segment of Shougouling fault is right-lateral strike slip while its east segment is dominantly right-lateral strike slip and thrust also; the motion modes of the west and the east branches of Zhujiangkou fault are both left-lateral strike slip and thrust also. The average Coulomb rupture stress rates p.a. of Guangzhou-Conghua fault and the east segment of Shougouling fault are evidently higher than those of the west segment of Shougouling fault and the west and the east branches of Zhujiangkou fault. The simulation results comparatively accord with the seismic activity features in this area.