伴随断层蠕动传播的准静态变形--模型理论分析及唐山地震前孕震断裂运动过程的讨论 |
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引用本文: | 张超.伴随断层蠕动传播的准静态变形--模型理论分析及唐山地震前孕震断裂运动过程的讨论[J].地震学报,1984,6(1):29-40. |
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作者姓名: | 张超 |
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作者单位: | 国家地震局地震地质大队 |
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摘 要: | 根据形变测量资料和有关实验结果以及某些地震前兆特征,本文提出了一种在粘弹性介质半空间中断层滑动面沿断裂带走向扩展,即断层蠕动传播的力学模型.为了研究其附近的形变特征,导出了蠕动传播所产生位移场的解析表达式,并通过数值积分计算了在广义开尔文介质中,滑动时间函数为△U=B(1-e-t/T),而蠕动事件沿断裂带单侧和双侧传播导致的附近介质位移的时空分布.根据1976年唐山地震前沧东断裂带上的短周期测量资料并参考模型所得出的结果,对震前的断层运动作了反推.结果表明,地震前沿沧东断裂带发生过明显的蠕动传播,其初始蠕动发生在小站和沧州之间,随后蠕动沿着断裂带向东北和西南传播,向西南扩展的滑动面是顺扭走滑运动,向东北扩展的滑动面以顺扭走滑运动为主并略有压性倾滑运动分量.
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QUASI-STATIC DEFORMATION ACCOMPANIED BY PROPA-GATION OF FAULT CREEP--A THEORETICAL MODEL ANALYSIS AND DISCUSSION ON THE CHARACTERI- STICS OF EARTHQUAKE FAULT MOVEMENT BEFORE THE 1976 TANGSHAN EARTHQUAKE |
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Abstract: | According to the geodetic data and the results from laboratory experimentation, as well as the precursory features of some earthquakes, in this paper a fault creep propagation model is given. The model simulates an extension of the dislocation surface along the fault belt in viscoelastic half-space. For studying the features of deformation nearby the belt, the analytical expressions for quasi-static deformation due to the creep propagation is derived and the author has obtained the theoretical fields of the displacement by the aid of numerical integration. In calculation, the material is taken to be the generalized Kelvin substance and we presume that the slip-time function is △U = B(1-e-t/T) and the creep events propagate unilaterally or bilaterally along the fault.With reference to the results from the model and by analysing the short period geodetic data observed in the stations along Candong fault belt before the 1976 Tangshan earthquake, an inversion of the development of the fault motion is made. It can be demonstrated that the obvious propagation of creep occurred along the belt and the initial creep source appears between the Xiao2han station and the Canzhou station. Then, the creep event propagated from this location to the northeast and south west directions along the belt, and the dislocation at the south west side of the initial creep source is right-lateral strike-slip, the dislocation at the northeast side is the same as above described, but with less compressional dip-slip component. |
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