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地质力学学报:2021,27(4):614-627
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2008年汶川大地震孕震、同震及震后变形和应力演化全过程的数值模拟
(1.中国科学院大学地球与行星科学学院, 北京 100049;2.中国科学院计算地球动力学重点实验室, 北京 100049;3.山东省嘉祥县精锐工业有限公司, 山东 济宁 272400)
Seismogenic, coseismic and postseismic deformation and stress evolution of the 2008 Wenchuan earthquake: Numerical simulation analysis
(1.College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China;2.Key Laboratory of Computational Geodynamics, Chinese Academy of Sciences, Beijing 100049, China;3.Shandong Jiaxiang Jingrui Industry Co., Ltd, Jining 272400, Shandong, China)
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投稿时间:2020-11-30    修订日期:2021-01-15
中文摘要: 2008年MS 8.0级汶川大地震发生在具有复杂的地质构造背景、强烈的地表起伏、不均匀的弹性和黏性结构的龙门山断裂带上。由于震前地震活动性不够强烈且地表构造变形较小,龙门山断裂带的地震危险性在汶川地震之前被低估。从数值模拟的角度,建立黏弹性有限元模型,考虑了初始地形、重力、构造加载、黏弹性松弛等因素对2008年汶川大地震的孕震、同震及震后150年变形全过程的影响,定量研究了映秀-北川断裂带的同震及震后变形,分析了弹性层、黏弹性层的应力积累、释放、调整的特点,模拟得到地表同震和震后位移与大地测量资料较为吻合,对汶川大地震的余震分布进行了力学上的解释,模拟得到震前、同震及震后的应力变化有助于深入分析大地震的动力学成因及其对周围区域的地震危险性影响。
Abstract:The 2008 MS 8.0 Wenchuan earthquake occurred in the Longmenshan fault zone, which has complex geological background, strong surface relief, and heterogeneous elastic-viscous structures; however, the seismic risk of the Longmenshan fault zone was underestimated before the Wenchuan earthquake due to the low seismicity and slight surface tectonic deformation. We established an elastic-viscous finite element model from the perspective of numerical simulation, taking multiple factors into consideration, such as initial topography, gravity, tectonic loading, and viscoelastic relaxation of the middle and lower crusts and the upper mantle. The effects of the mentioned factors on the dynamic process of seismogenic and coseismic deformations of the 2008 Wenchuan earthquake as well as the postseismic deformation in 150 years were analyzed. We quantitively studied the coseismic and postseismic deformations of the Yingxiu-Beichuan fault zone, and summerized the characteristics of stress accumulation, release, and adjustment in both the elastic and viscoelastic layers. The simulation results of the surface coseismic and postseismic displacements showed a good agreement with the geodetic data, and the aftershock distribution of the Wenchuan earthquake was explained in mechanics. The changes in preseismic, coseismic, and postseismic stress were calculated to analyze the dynamic cause of the Wenchuan earthquake and the influence on the seismic risk of surrounding areas.
文章编号:     中图分类号:P313.2;P313.4;P313.5    文献标志码:
基金项目:国家自然基金面上项目(42074117,41474085)
引用文本:
孟秋,高宽,陈启志,等,2021.2008年汶川大地震孕震、同震及震后变形和应力演化全过程的数值模拟[J].地质力学学报,27(4):614-627.DOI:10.12090/j.issn.1006-6616.2021.27.04.051
MENG Qiu,GAO Kuan,CHEN Qizhi,et al,2021.Seismogenic, coseismic and postseismic deformation and stress evolution of the 2008 Wenchuan earthquake: Numerical simulation analysis[J].Journal of Geomechanics,27(4):614-627.DOI:10.12090/j.issn.1006-6616.2021.27.04.051

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