昆仑山大地震震后形变反映的地壳岩石流变特性  

Numerical simulation of crust rheological property reflected by post-seiemic deformations of Kunlun large earthquake

作　　者：张晁军[1,2] 石耀霖[2] 马丽[3] 

机构地区：[1]中国地震台网中心信息网络部,北京100045 [2]中国科学院研究生院地球科学学院计算地球动力学实验室,北京100049 [3]中国地震局地震预测研究所,北京100036

出　　处：《岩土力学》2009年第9期2552-2558,共7页Rock and Soil Mechanics

基　　金：中国科学院知识创新工程重要方向项目资助(No.KZCX2-VW-134);国家自然科学重大研究项目重点基金(No.90814014)资助;973课题(2004CB418405)资助;地震基本科研业务项目(0207690205)资助

摘　　要：2001年昆仑山地震是我国近50年来最大的地震。用3种模型对震后中国地震局跨断层布设的4个GPS站点记录到显著的震后形变进行了模拟研究。结果表明:单纯的上地壳10km为滞弹性的模型不能解释震后形变的幅度;30km的弹性上地壳覆盖在40km的柔性下地壳上的松弛模型可以解释变形速率指数衰减的主要特征;而两个模型的结合不但能解释整体指数衰减的特征,而且还能更好地拟合震后最初几周的较高形变速率。结果表明,在昆仑山断层两侧存在着流变性质的差异。The Mw7.8 Kunlun earthquake of 14 November, 2001, in the northern Tibetan Plateau of China, is the largest event in the Chinese continent in the latest 50 years. In this paper, layered viscoelastic models are calculated by PSGRN/PSCMP code; and the results are used to fit post-seismic deformation obtained from four GPS stations of CEA across the earthquake fault. The results show that model of a single anelastic layer of 10 km thick upper crust overlying an elastic lower crust cannot explain the amplitude of deformation; the relaxation model of 30 km elastic upper crust overriding 40 km ductile lower crust can explain the main features of exponential attenuation of post-seismic deformation. Combination of the two models, however, can fit the character better with deformation rate being higher in the first few weeks and slower rate thereafter. The viscous layer of lower crust provide the main control of the post-seismic deformation of long term decay of deformation in months, while the upper anelastic layer may contribute to the high rate of initial few weeks after the main earthquake. The result also suggests that rheological differences exist at two sides of the Kunlun Mountains fault.

关 键 词：震后形变 黏滞系数 流变模型 滞弹性 标准线性固体 Maxwell体 

分 类 号：P554[天文地球—构造地质学]