芦山Ms7.0地震产生的静态库仑应力影响研究

The Coulomb stress change caused by the 2013 Ms7.0 Lushan Earthquake

2013年4月20日在四川芦山发生了Ms7.0地震,震源深度17 km,发震断层位于龙门山断裂带南段的前山断裂附近,为逆冲断层机制,芦山地震震中位置位于2008年汶川Ms8.0地震西南方向85 km处,两个地震的余震分布区中间存在一个约20~30 km的破裂空段。首先计算汶川地震的静态库伦应力,明确汶川地震对芦山地震的触发影响,芦山地震的发震位置处于汶川地震后的应力加载区域;进一步计算芦山地震对周围的静态库仑应力,结果显示,芦山地震对二者之间破裂空段的影响为应力加载;最后计算汶川地震和芦山地震周围的静态库仑应力的综合影响,二者对川滇交界东部的应力加载作用是明确的,对中间存在的20~30 km的空段也存在一定的应力加载影响。

The Ms7.0 Lushan Earthquake on 20 April 2013,Sichuan Province,resulted from a north-south striking fault with reverse-type motion.This event occurred on the southern part of Longmenshan fault.The epicenter of the Ms7.0 Lushan Earthquake locates southwest 85 km from the Ms8.0 Wenchuan Earthquake on 12 May 2008.There is a seismic gap segment with 20 to 30 km long along the main rupture fault between two earthquake groups.In this study,we calculated the Coulomb stress change induced by the Ms8.0 Wenchuan Earthquake at first and then find that the Ms7.0 Lushan Earthquake was induced by the Ms8.0 Wenchuan Earthquake.Our analysis results show the Ms7.0 Lushan Earthquake epicenter is located in the increasing region of Coulomb stress after the Ms8.0 Wenchuan Earthquake.Then we calculate the Coulomb stress change caused by the Ms7.0 Lushan Earthquake and find that the influence of the Ms7.0 Lushan Earthquake on the gap segment results from the increasing of Coulomb stress.Furthermore we calculated the stress change of the region nearby induced by both the Wenchuan and the Lushan earthquakes.The Coulomb stress of the eastern border between Sichuan and Yunnan provinces has been increased as well.