九寨沟地震发震断层属性及青藏高原东南缘现今应变状态讨论  

Discussion on seismogenic structure of Jiuzhaigou earthquake and its implication for current strain state in the southeastern Qinghai-Tibet Plateau

作　　者：徐锡伟[1] 陈桂华[1] 王启欣[1] 陈立春[1] 任治坤[1] 许冲[1] 魏占玉[1] 鲁人齐[1] 谭锡斌[1] 董绍鹏[1] 石峰[1] XU Xi-Wei CHEN Gui-Hua WANG Qi-Xin CHEN Li-Chun REN Zhi-Kuri XU Chong WEI Zhan-Yu LU Ren-Qi TAN Xi-Bin DONG Shao-Peng SHI Feng(Key Lab of Active Tectonics ＆ Volcano, Institute of Geology, China Earthquake Administration, Beij ing 100029, China)

机构地区：[1]中国地震局地质研究所活动构造与火山重点实验室,北京100029

出　　处：《地球物理学报》2017年第10期4018-4026,共9页Chinese Journal of Geophysics

基　　金：国家公益性重大行业科研专项"中国地震活动断层探察"(201108001;201408023);国家自然科学基金重大计划课题(91214201)联合资助

摘　　要：九寨沟地震(M_s7.0或M_w6.5)震中位于青藏高原巴颜喀拉块体东缘东昆仑断裂带东端塔藏断裂、岷江断裂和虎牙断裂交汇部位,中国地震局相关科研机构的研究人员曾将该震中区判定为玛沁—玛曲高震级地震危险区.地震应急科学考察期间没有发现地震地表破裂带,但地震烈度等震线长轴方位、极震区基岩崩塌和滑坡集中带、重新定位余震空间展布和震源机制解等显示出发震断层为NNW向虎牙断裂北段,左旋走滑性质,属东昆仑断裂带东端分支断层之一.此外,汶川地震后,在青藏高原东缘和东南缘次级活动断层上发生了包括2017年九寨沟地震(Mw6.5)、2014年鲁甸(M_w6.2)、景谷(M_w6.2)、康定(M_w6.0)等多次中强地震,显示出青藏高原东缘至东南缘各块体主干边界活动断层现今处于中等偏高的应变积累状态,即在巴颜喀拉、川滇等块体主干边界活动断层上具备了发生高震级(M_w≥7.0)地震的构造应力-应变条件,未来发生高震级地震的危险性不容忽视.The Jiuzhaigou earthquake （MS7.0 or MW6.5） occurred in the intersection area among the Tazang, Minjiang and Huya faults in the eastern part of the Bayan Har block of the Qinghai-Tibet Plateau. Some researchers from the relevant research institutions of China Earthquake Administration have identified the epicenter of the Jiuzhaigou earthquake and its adjacent areas as a high-magnitude earthquake risk area. Although no surface rupture zone was discovered during the emergency scientific investigation, the focal solutions, spatial linear distributions of the relocated aftershocks and earthquake-triggered bedrock collapses or landslides in the epicenter, with a dominated axial azimuth of the earthquake intensities display that the northern segment of the Huya fault, a NW-trending left-lateral strike-slip fault is the seismogenic fault of the Jiuzhaigou earthquake, and belongs to one of the tail structure at the easternmost end of the eastern Kunlun fault zone. In addition, after the Wenchuan earthquake, repeatedly occurred on the secondary active faults in the eastern and southeastern Qinghai-Tibet Plateau, the 2017 Jiuzhaigou （MW6.5）, 2014 Ludian （MW6.2）, Jinggu （MW6.2）, and Kangding （MW6.0） earthquakes. According to the GPS data, it is shown that the major active faults along the boundaries of the Bayan Har and the Sichuan-Yunnan blocks in the eastern and southeastern Qinghai-Tibet Plateau are now in a middle-high strain accumulation state and the risk of occurrence of high-magnitude earthquakes （MW ≥ 7.0） can not be ignored in the future.

关 键 词：九寨沟地震 发震断层 应变积累条件 青藏高原 

分 类 号：P541[天文地球—构造地质学]