龙门山和鲜水河断裂带对区域构造加载作用的动态响应  

Dynamic responses of the Xianshuihe and Longmenshan fault zones to regional tectonic loading

作　　者：王晓芳[1] 肖捷[2] 许鹤华[1] 何建坤[2] 

机构地区：[1]边缘海地质重点实验室,中国科学院南海海洋研究所,广州510301 [2]大陆碰撞与隆升重点实验室,中国科学院青藏高原研究所,北京100101

出　　处：《地球物理学报》2016年第4期1403-1413,共11页Chinese Journal of Geophysics

基　　金：中国科学院南海海洋研究所青年人才领域前沿项目(SQ201211)资助

摘　　要：为了研究汶川地震和鲜水河断裂带上的地震之间是否有触发作用及区域构造加载作用在这些地震发生过程中对应力场的影响.我们以汶川地震和鲜水河断裂带所在区域上的共7次地震为研究对象,区域构造加载作用由GPS速度边界近似,用分裂节点技术模拟上地壳地震的发生,并采用三维黏弹性有限元方法,模拟库仑应力的演化.研究结果表明：鲜水河断裂带上的地震震前积累的库仑应力的17%～38%来自区域构造加载的持续作用,其他的地震形变引起的库仑应力的积累约占49%～67%,故地震触发作用明显（除1948年理塘地震和1973年炉霍地震外）;而汶川地震震前1893—1981年发生的地震释放了该区部分库仑应力,不可能对汶川地震有触发作用.汶川地震的库仑应力积累可能主要来自区域构造加载作用,地震发生以后几乎释放了所在区域的所有库仑应力,形成新的格局.In order to study the trigger interaction between the Wenchuan earthquake and the earthquakes on the Xianshuihe fault zone as well as the stress changing with the effect of regional tectonic loading,we have studied the seven major earthquakes in the Xianshuihe and Longmenshan fault zones.The regional tectonic loading is approximated by velocity boundaries from GPS data.The split-node technique was used to simulate the earthquakes in upper crust. With the threedimensional viscoelastic finite element code we simulated the evolution of Coulomb stress.The results show that the trigger interaction between the Wenchuan earthquake and the earthquakes on Xianshuihe fault zone is different.The trigger interaction is obvious on the Xianshuihe fault zone（except the Litang earthquake in 1948 and the Luhuo earthquake in 1973）,as 17 to 38percentages′Coulomb stress increasing was caused by regional tectonic loading,other49 to 67percentages of stress was contributed by earthquake deformation.However,part of theCoulomb stress was released by the earthquakes that happened from 1893 to 1981.So it is impossible that the Wenchuan earthquake was triggered by the earthquakes in the past.The Coulomb stress in the Wenchuan earthquake was mainly increased from regional tectonic loading.With occurrence of this earthquake,the certain region released almost all the Coulomb stress and became into a new condition.

关 键 词：汶川地震 龙门山断裂带 鲜水河断裂带 破裂库仑应力 有限元方法 

分 类 号：P315[天文地球—地震学]