青海玉树Ms7.1级地震同震地表破裂构造  

Structural analysis of the co-seismic surface ruptures associated with the Yushu Ms7.1 earthquake,Qinghai Province

作　　者：周春景[1,2] 吴中海[1] 尼玛次仁 李家存[4] 蒋瑶[5] 刘艳辉[5] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]中国地质科学院,北京100026 [3]西藏地质调查院一分院,西藏堆龙德庆851400 [4]首都师范大学,北京100048 [5]中国地质大学(北京),北京100083

出　　处：《地质通报》2014年第4期551-566,共16页Geological Bulletin of China

基　　金：中国地质科学院地质力学研究所基本科研业务费(编号:DZLXJK201212);中国地质调查局项目(编号:1212011120163)

摘　　要：分析了青海玉树Ms7.1级地震中形成的同震地表破裂分布与构造特征.本次地震造成的地表破裂长这46km,地震造成240cm的最大相对水平走滑错动量,最大垂直错动量60cm.地表破裂所经之处可看到原有断层新近活动的明显迹线.依次分析了按空间尺度划分的4个层次破裂的走向变化、同级破裂排列、破裂末端变化等构造特征.Ⅰ级破裂作为本次地震产生的整个破裂带,总体走向119°,由3段自然分开、左阶斜列的Ⅱ级破裂组成.3段Ⅱ级破裂自NW向SE依次为隆宝镇段、结古镇段和禅古寺段,破裂性质总体以左旋走滑为主,各段略有不同.各Ⅱ级破裂带内部,分别由若干Ⅲ级破裂段落组成,总体呈现右阶斜列排列模式.Ⅲ级破裂本身由一系列简单的Ⅳ级破裂雁列或羽列右阶斜列构成.不同层次的地表破裂具有简单剪切构造带的变形特征,共识别出R、R’、Y、T和P五组基本破裂面.其初始破裂面展布特征可以用库伦破裂准则来解释,其中岩土体材料的内摩擦角大致为26～44°.各级破裂端部出现分叉、转向及逐渐消失等变形特征.The Yushu Ms7.1 earthquake in Yushu area,Qinghai Province,China,caused a 46km-long surface rupture,with a maximum horizontal left-slip displacement of 240cm and a maximum vertical displacement of about 60cm.The surface rupture distributed along the pre-existing Garzi-Yushu active fault.Four levels of ruptures can be classed on different scales and structural characters.They are level Ⅰ,Ⅱ,Ⅲ and Ⅳ from large scale to small one in sequence.Level Ⅰ rupture,the surface rupture as a whole caused by this earthquake,generally strkes E119°S and comprises three level Ⅱ ruptures,i.e.Longbao Town Section,Jiegu Town Section and Changu Temple Section respectively from the northwest to southeast.A level Ⅱ rupture usually consists of a dozen of level Ⅲ ruptures.Leve Ⅳ rupture is the smallest one which can be figured out on the ground in the field survey.Tens or hundreds of level Ⅳ ruptures constitute a level Ⅲ rupture.Different levels of rupture may have different mode in arrangement,with a left step among the Level Ⅱ ruptures and a right step mode among both level Ⅲ and Ⅳ respectively.However,different level ruptures have the similar character of the Riedel Shear structures and five basic shear planes,R,R＇,Y,T and P,can be identified.The angles of internal friction of the initial fault plane is 26～44°according to Coulomb failure criterion.

关 键 词：玉树地震 同震地表破裂 破裂分级 里德尔剪切 走滑断裂 

分 类 号：P315.2[天文地球—地震学]