根据2001年Mw7.8可可西里强震InSAR同震测量结果反演东昆仑断裂两侧地壳弹性介质差异  

Crustal elasticity contrast across the East Kunlun fault in northern Tibet inferred from InSAR measurements of the 2001 Mw 7.8 Kokoxili earthquake

作　　者：陶玮[1] 沈正康[1] 万永革[1] 单新建[1] 马超[1] 

机构地区：[1]中国地震局地质研究所

出　　处：《地球物理学报》2007年第3期744-751,共8页Chinese Journal of Geophysics

基　　金：国家自然科学基金重点项目(40334042);科技部国家重点基础研究发展计划"973项目"(2004CB418403);和国家自然科学基金项目(40504014)资助

摘　　要：利用2001年Mw 7．8可可西里强震InSAR同震测量结果，反演了青藏高原北部东昆仑断裂两侧地壳弹性介质差异．InSAR测量结果显示断层南侧的同震位移比北侧的大20％～30％．根据人工地震反射剖面建立岩石圈模型，以断层两侧杨氏模量差异和震源破裂深度为反演变量，通过有限元方法模拟实测得到的同震位移剖面．反演得到最佳断层破裂深度为20～22km，断层南侧杨氏模量相对北侧比值为81％～92％．结果表明，断层两侧弹性介质性质存在明显差异，由于构造运动作用，断层南部地壳不及北部地壳坚硬．前人利用地震层析成像和大地电磁测深等手段推断青藏高原内昆仑山断裂以南可可西里一羌塘地块地壳内广泛发育低速高导层，我们通过形变场力学分析得到与此相一致的结果．We use coseismic deformation data of the 2001 Mw 7.8 Kokoxili earthquake obtained from InSAR measurements to study crustal elasticity contrast across the East Kunlun fault. Coseismic deformation field of the earthquake documented by InSAR studies indicated that the displacements on the south side were 20 % - 30 % higher than that on the north side of the fault. We develop an elastic finite element model and invert InSAR data from two deformation profiles to estimate two parameters： the Young＇ s modulus contrast across the fault and the fault rupture depth. The starting lithospheric structural model is adopted from a seismic reflection study on the north side of the East Kunlun fault. Our result shows optimal estimates of the earthquake rupture depth as 20 - 22 km and the crustal Young＇ s modulus contrast between the south and north side as 81% -92%. Such a result, obtained from study of crustal deformation, suggests a softer crust south than north of the fault, which is cdnsistent with previous tomographic and magnetotelluric studies of a low-velocity and high-conductivity layer existing in lower crust of the Kokoxili-Qiangtang block south of the Kunlun fault.

关 键 词：INSAR 同震变形 反演 弹性差异 青藏高原 

分 类 号：P227[天文地球—大地测量学与测量工程] P541[天文地球—测绘科学与技术]