Mechanism of Postseismic Deformation of Ground Surface Following the 1999 Chi‐Chi Earthquake, Taiwan
Mechanism of Postseismic Deformation of Ground Surface Following the 1999 Chi‐Chi Earthquake, Taiwan
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DOI：
10.1002/cjg2.20042
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发表时间：
2013-07
期刊：
影响因子：
--
通讯作者：
Fu Zhen;Zhang Hai-ming;Cai Yong-en
中科院分区：
文献类型：
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作者：
Fu Zhen;Zhang Hai-ming;Cai Yong-en
1999年台湾集集地震后450天的GPS测量显示，震后位移从几十毫米到数百毫米不等。引起地表震后变形的两种可能机制是下地壳的粘性松弛和地震断层的无震蠕变引起的后滑。本文采用粘弹性接触问题的有限元方法，以GPS数据为约束条件，模拟了1999年集集地震的震后变形过程。并讨论了粘性松弛和后滑移两种可能的机制。结果表明，GPS观测到的震后形变可以很好地用粘滞松弛机制来解释。用试错法估算出台湾地区下地壳的粘性为1017Pa.S。采用速率和状态相关摩擦定律的数值方法，研究了余滑机制对集集地震震后变形的影响。结果表明，GPS数据不能单独用余滑机制来解释，它只影响主震后50d的震后形变。这些研究将有助于理解1999年台湾集集地震震后形变的机制。
GPS measurements of 450 days after the 1999 Chi-Chi, Taiwan, earthquake revealed large postseismic displacement from dozens to hundreds of millimeters. Two possible mechanisms responsible for the postseismic deformation of the surface are the viscous relaxation of the lower crust and the afterslip caused by the aseismic creep of the earthquake fault. In this study, the finite element method (LDDA) for the viscoelastic contact problems is used to simulate the postseismic deformation process of the 1999 Chi-Chi earthquake with the GPS data as constraints. And the two possible mechanisms, viscous relaxation and afterslip, are discussed. The results indicate that the postseismic deformation observed by GPS can be well explained by the viscous relaxation mechanism. The viscosity of the lower crust below the Taiwan area is estimated as 1017 Pa·s by the trial-and-error method. The effect of afterslip mechanism on the postseismic deformation of the Chi-Chi earthquake is investigated by the numerical method with rate-and-state dependent frictional law. The results suggest that the GPS data cannot be explained by the afterslip mechanism alone, which only affects the postseismic deformation in the early 50 days after the mainshock. These studies will throw light on understanding the mechanism of the postseismic deformation of the 1999 Chi-Chi, Taiwan, earthquake.