2001年东昆仑地震(Ms=8.1)不对称的同震地表破裂构造——单侧块体运动为主及青藏高原内部物质向东滑移的证据  

Asymmetrical Co-seismic Surface Ruptures in the East Kunlun Earthquake (Ms=8.1), Northern Tibetan Plateau, China

作　　者：李海兵[1] 戚学祥[1] 朱迎堂 杨经绥[1] Paul TAPPONNIER 史连昌 王永文 

机构地区：[1]中国地质科学院地质研究所大陆动力学实验室 [2]青海地质调查院 [3]Institut de Physique du Globe de Paris, 4, Place Jussieu, 75252 Paris Cedex 05, France

出　　处：《地质学报》2004年第5期633-640,i004-i006,共11页Acta Geologica Sinica

基　　金：科技部重大基础研究前期研究专项 (编号 2 0 0 2 CCA0 5 10 0 );国家重点基础研究发展规划项目 (编号 G19980 40 80 0 );国土资源大调查地质调查项目 (编号 DKD2 0 0 10 0 3 );国家自然科学基金项目 (编号 40 2 72 0 96)资助的成果

摘　　要：通过对 2 0 0 1年 11月 14日发生的东昆仑地震 (Ms=8.1)地表破裂带的野外考察 ,发现沿东昆仑断裂带发育一类不对称的同震地表破裂构造 :单侧垂直破裂带的张裂隙构造、不对称式拉分构造以及冻土层范围内的低角度逆冲构造。这些不对称的同震地表破裂构造不仅指示发震断裂为左行走滑 ,而且表明以断裂南侧块体向东运动为主、北侧块体向西甚微运动 (以地震前同地为参照系 )的运动学特征。与 GPS的观测数据结果所反映的运动特征基本一致 ,同时与不对称的区域稳定性相吻合。这种反映单侧块体运动为主的不对称同震地表破裂构造在大陆地震破裂带中是少有的 ,它的发现不仅表明东昆仑断裂以南的青藏高原内部物质向东滑移 ,而且由此认为自全新世以来其向东滑移的速率有可能约略小于 10～ 12 m m/ a,并同时指示断裂南侧相对于北侧为地震地质灾害更严重地域。Field investigations show that the East Kunlun earthquake (Ms=8.1) on November 14th 2001 produced a type of asymmetrical co-seismic surface rupture structures, such as open-crack systems perpendicular to surface rupture zones, asymmetrical pull-apart structures and low-angle thrusts within frozen soil layers. These asymmetrical co-seismic surface rupture structures show that faults are left-lateral slipping and the southern sides of the faults moved eastward, i.e., the southern sides of the faults are the main active part. GPS data also show basically the same kinematics on the south (Tibet) and the north (the Qaidam Basin) sides of the faults. In addition, this kinematics results also accord with asymmetric district stability across the faults. The asymmetrical co-seismic rupture structures reflected a single-side movement along the active Kunlun Fault, and are an unwonted structure in typical interseismic structures, which indicate that the Kunlun Fault partitions its deformation into an eastward extrusion of Tibet to accommodate the continuing penetration of the Indian plate into the Eurasian plate, and the southern side of the Kunlun Fault moves eastward. The long-term eastward slip rate is determined to be about 10～12 mm/a or less, and the southern sides are more dangerous than the northern sides of the faults.

关 键 词：地表破裂 东昆仑 块体运动 青藏高原 地震 逆冲构造 左行走滑 滑移 冻土层 断裂 

分 类 号：P315.2[天文地球—地震学]