巴颜喀拉块体北东地区现今水平运动与变形  

Present-day Horizontal Motion and Deformation in the Northeast Part of the BarYan Har Block

作　　者：陈长云[1,2,3] 任金卫[3] 孟国杰[3] 张军龙[3] 杨攀新[3] 杨永林[4] 苏小宁[3] 苏建峰[2] 

机构地区：[1]中国地震局地质研究所,北京100029 [2]中国地震局第一监测中心,天津300180 [3]中国地震局地震预测研究所,北京100036 [4]四川省地震局测绘工程院,四川雅安625000

出　　处：《地震》2012年第4期73-82,共10页Earthquake

基　　金：国家"973"计划项目(2008CB425701);岷江断裂北部活动性及危险性评价(02092437)

摘　　要：本文利用GPS数据研究了巴颜喀拉块体北东地区现今水平运动与变形特征。在球坐标系中解算了各应变分量,分析了应变率场的空间分布特征,并与地球物理学和地震地质学研究结果进行了综合对比分析。最新的GPS速度场结果表明,巴颜喀拉块体北东地区与高原整体运动性质一样具有顺时针向南东方向旋转的特征,自西向东和北东方向测站水平运动速度呈现明显的衰减特征。应变场结果显示,研究区以北东向的主压应变为主,伴随着近北西向的张性应变。应变较强的区域主要分布在活动块体的边界断裂——东昆仑断裂带的东段塔藏段和龙门山断裂带上。东昆仑断裂带东段塔藏段的主压应变明显,结合地震地质和活动构造资料,认为东昆仑断裂带东段塔藏段的运动性质自西向东发生了改变,水平滑动速率逐渐减小,垂向运动逐渐增强。研究区GPS速度场和应变场的这一变形特征表明,青藏高原内部的块体运动特征较为明显,变形主要集中在作为活动块体边界的活动断裂带上,边界断裂带的运动特征在调节活动块体间的相互运动中起着重要作用。We have collected GPS data in the period of 2001—2009 from the Crustal Motion Observation Network of China in northwest of Sichuan,and the newest observation data from observed campaign stations which were built under the support of the National Key Basic Research Development Program,to study the characteristics of present-day crustal horizontal motion velocities in the research zone.Strain rate components are computed in spheric coordinate system.Analyses of the spatial distribution strain rate fileds derived from GPS measurements are carried out in contrast with seismological and geological results.Results show that the horizontal motion of the GPS stations are consistent with the clockwise rotation of the whole Tibetan Pleatau around the Eastern Himalayan syntaxis.From west to east and northeast,the velocity decreases obviously.The principal compression strain rates are apparently greater than principal extension strain rates,especially in Tazang fault,the eastern part of Dongkunlun fault and the middle part of the Longmenshan fault.The principal compress strain is obviously in the eastern segment of the Dongkunlun fault.Combining analysises with the data of earthquake geology and active tectonics,we suggest that the motion characteristics may be changed from west to east,in the west,the fault shows an obviously left lateral strike-slip,but in the eastern segment,it not only show a left lateral motion but also an compress movement.The motion characteristics of the boundary fault plays an important part in adjusting the relative motion with the blocks.Based on the velocity filed and strain filed from GPS data,we think that the motion in the reasearch zone can be thought as a block motion,most obvious deformation mainly on the boundary faults of the active blocks.

关 键 词：GPS观测 水平运动 应变率场 速度场 巴颜喀拉块体 

分 类 号：P315.7[天文地球—地震学]