汶川地震的发生对周围断层稳定性影响的数值模拟  

Numerical Simulation on Influences of Wenchuan Earthquake on the Stability of Faults in the Neighborhood

作　　者：李玉江[1] 陈连旺[1] 陆远忠[1] 詹自敏[1] 

机构地区：[1]中国地震局地壳应力研究所地壳动力学重点实验室,北京100085

出　　处：《地球科学（中国地质大学学报）》2013年第2期398-410,共13页Earth Science-Journal of China University of Geosciences

基　　金：中国地震局地壳应力研究所基本科研业务专项(No.ZDJ2010-12;2012-09);国家科技支撑项目(No.2012BAK19B03)

摘　　要：大地震发生后,研究地震的发生对周围断层的影响尤为重要.利用川西-藏东地区三维粘弹性有限元模型,考虑地表高程和粘弹性松弛等因素的影响,研究主要断裂带库仑应力累积速率和汶川地震的发生对周围断层的影响.结果表明:(1)龙门山断裂带年累积速率为0.28×10-3～0.35×10-3MPa/a,这种较小的累积速率与龙门山断裂带强震较长复发间隔一致;(2)汶川地震的发生除造成震源区应力减小外,还造成断裂带北东段不同程度的应力增加,这与震后余震的分布基本吻合;(3)鲜水河断裂北西段、东昆仑、龙日坝、岷江以及虎牙断裂库仑应力水平增加显著,且汶川地震对于玉树地震的发生有微弱的加载效应;(4)汶川地震的发生造成鲜水河断裂带强震复发间隔缩短约52～104a,是值得关注的强震危险区.When a major earthquake occurred, it＇s critical to analyze the influences on the surrounding faults and the potential seismic activity. In this paper, a complex viscoelastic model of western Sichuan and eastern Tibet regions is constructed including the topography, and then we find out the Coulomb failure stressing rate on these major faults and calculate the stress change caused by the Wenchuan earthquake taking the post-seismic relaxation into consideration. Our preliminary results indicate that： （1） the Coulomb stressing rate in the Longmen Shan fault is lower with values from 0. 28 × 10^-3 MPa/a to 0. 35 × 10^- 3 MPa/a, which is consistent with the previous long reccurrence interval of Wenchuan earthquake; （2） The Wenchuan earthquake not only caused the Coulomb failure stress decrease in the source region, but also the stress increase in the northeastern segment, and it＇s comparatively consistent with the aftershock distribution; （3） The Coulomb failure stress change caused by Wenchuan earthquake showed significant increase on five major fault segments, which were northwestern segment of Xianshui fault, eastern Kunlun fault, Longriba fault, Minjiang fault and Huya fault respectively, also the Coulomb failure stress on the fault plane of the Yushu earthquake was faintly increased; （4） The characteristic earthquake recurrence interval of the Xianshui fault is delayed by 52-104 a deduced from the Wenchuan earthquake, so it＇s ranked the high seismic hazard region in the future.

关 键 词：龙门山断裂带 汶川地震 应力累积速率 库仑破裂应力 数值模拟 

分 类 号：P553[天文地球—构造地质学]