【摘要】 2010年4月14日,青海省玉树地区发生Ms7.1级地震,造成大量人员伤亡和财产损失。地震发生后,我们对地震地表破裂带进行了详细的考察,并对同震位移量进行了精确的测量。根据野外考察和测量的结果,对玉树地震的地表破裂特征、同震位移量及其分布特征进行了分析,并对地震的破裂机制和破裂过程进行了探讨,取得如下认识:(1)玉树地震形成了沿鲜水河断裂带西北段(甘孜-玉树断裂)分布的东、西两条地表破裂带,西段破裂带分布在微观震中附近的隆宝湖拉分盆地中,长约19km;东段破裂带沿扎曲河南岸及巴塘河西岸山坡展布,长度约31km;上述两条破裂带之间存在约15km的地表破裂空区;(2)野外测量获得玉树地震的最大同震位移量为2.3m,位于东段地表破裂带中部郭央烟宋多附近;(3)地表破裂和野外构造地貌特征均反映了发震断层处于走滑伸展环境,断层左旋走滑过程中伴随正断作用;(4)地震波反演结果和地表破裂分布特征表明,玉树地震的破裂过程包括两次子事件,分别在地表形成了隆宝湖破裂带和扎曲河、巴塘河破裂带,隆宝湖及玉树县城西侧的山间谷地是在甘孜-玉树断裂长期活动的破裂带阶区转换拉张过程中形成的两个拉分盆地。更多还原

【Abstract】 On 14 April 2010,an earthquake(Ms7.1) happened in the Yushu region,Qinghai Province,causing large casualties and property losses.After the earthquake,we carried out a detailed investigation of the earthquake surface rupture zone,and accurately measured co-seismic displacements.Based on our field investigation and measurements,the characteristics of the Yushu earthquake surface ruptures and coseismic displacements and their distribution pattern were analyzed.The earthquake rupture mechanism and the rupture process were discussed.According to our research,the following understandings were obtained:(1) The Yushu earthquake produced two surface ruptures along the northwest section of the Xianshuihe fault(Ganzi-Yushu fault).The western surface rupture is located in the Longbao lake pull-apart basin near the micro-epicenter,and is about 19km long.The eastern surface rupture is located along the hillsides south of Zhaqu river and the west of the Batang river,and is about 31km long.There is a ～15km gap between the former two segments of the surface rupture zone.(2) Field measurements show that the maximum coseismic displacement for the Yushu earthquake is 2.3m,located at the center of the eastern surface rupture,near the Guoyangyansongduo village.(3) The characteristics of the surface rupture as well as field tectonic geomorphology indicate that the ruptured fault is developed in transtensional setting.Tension normal fault developed during the sinistral strike-slip process of the fault.(4) Seismic data invertion result and the distribution of the surface rupture show that the Yushu earthquake consist of two sub-events,which formed the Longbao lake surface rupture zone and Zhaqu river-Batang river surface rupture zone,respectively.The valley west of Yushu City and the Longbao Lake are both pull-apart basins formed during the transtension activity of the fault.更多还原