中文摘要：

2010年4月14日在青海玉树发生的Ms7.1级地震造成了严重的人员伤亡和重大的财产损失.根据现场考察结果,本次地震形成了长约51km的地震地表破裂带,性质为左旋走滑,最大水平位错约1.8m,其发震断裂为甘孜-玉树断裂的玉树段.在此之前,于1738年12月23日前在玉树附近还发生过另外一次大地震,造成全户伤亡无存或不堪成户的达56户,被伤157户.现行地震目录将其震级确定为6（1/2）级.本文通过对地震史料的考证研究,结合历史地震形变带特征分析,认为本次地震的震级可达7（1/2）级左右,发震断裂为甘孜-玉树断裂的玉树段和当江段的组合破裂,而2010年玉树7.1级地震仅是其中的玉树段再次破裂的结果,因此,其西侧的当江段具有再次破裂活动的较大危险性.

英文摘要：

An earthquake occurred in Yushu of Qinghai Province with Ms 7. 1 on April 14,2010. This earthquake caused lots of people dead or injured and serious property loss. According to the field investigation, there was about 51 km rupture by left-lateral strike-slip faulting. The largest horizontal offset is about 1.8 m and the Yushu segment of Ganzi-Yushu active fault is the causative structure. There was another large earthquake occurred in Yushu nearby before December 23,1738 A. D. and caused about 56 family members dead or couldn＇t be a whole family again, about 157 family members serious injured. The magnitude of this earthquake is about 6 1/2 drawn from the present earthquake catalogs. The basis of textual research on the historical earthquake data and the features of historical rupture,we definitely suggest that the magnitude of this earthquake in 1738 A. D. reaches about 7 1/2, and the causative structure is the combination of Dangjiang and Yushu two segments of the Ganzi-Yushu active fault. But the earthquake of Ms 7. 1 in 2010 is only the result of Yushu single segment rupturing. So the western Dangjaing segment has high risk to rupture again in the future.