昆仑山大地震震后形变反映的地壳岩石流变特性

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10 km为滞弹性的模型不能解释震后形变的幅度；30 km的弹性上地壳覆盖在 40 km 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。

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

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.