| 2008年汶川大地震同震、震后形变和应力及对松坪沟地质灾害的影响 |
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| 引用本文：谢世亮,孙玉军.2021.2008年汶川大地震同震、震后形变和应力及对松坪沟地质灾害的影响[J].地球学报,42(5):691-700. |
| DOI：10.3975/cagsb.2021.010401 |
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| 基金项目:国家自然科学基金项目“龙门山前缘新生代沉积不均匀性的动力学机制模拟研究”(编号: 41874114);中国地质科学院基本科研业务费项目“青藏高原东缘地表过程与深部动力作用研究”(编号: YYWF201720) |
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| 中文摘要:2017年在四川茂县松坪沟发生的新磨滑坡造成了重大人员伤亡。除了分析降雨、工程地质等因素外, 前人提出地震对滑坡的形成也起到了重要作用, 然而目前还缺乏详细的定量分析。本研究根据龙门山地区地壳结构和GPS观测, 结合美国地质调查局USGS反演得出的汶川地震同震破裂模型, 利用粘弹性分层半无限空间模型(PSGRN/PSCMP程序)计算了汶川地震引起的同震和震后形变及应力场变化, 并详细分析了对松坪沟地区的形变和应力。结果表明汶川地震同震破裂造成松坪沟地区发生了明显地表位移, 并且震后的粘弹性松弛效应使得变形在该区持续加强。汶川地震同震破裂在松坪沟地区造成的东向位移为26.8~42.3 cm, 北向位移为7.4~8.0 cm, 该区处于垂向位移上升和下降的过渡地带, 变化量为–0.1~1.7 cm; 震后9年在同震的基础上东向位移继续增加约2.5 cm, 北向位移增加约7.4~8.0 cm, 松坪沟的北西段处于垂向位移持续上升区, 而南东段处于垂向位移下降区, 震后形变造成平均地形梯度增大, 有利于滑坡灾害的发生。鉴于松坪沟断裂性质的不确定, 汶川地震同震和震后引起的库仑应力改变对其活动性会产生不同的影响。 |
| 中文关键词:龙门山 汶川地震 新磨滑坡 震后形变 库仑应力 |
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| The Co-seismic and Post-seismic Deformation and Stress of Wenchuan Earthquake in 2008 and Their Influence on the Songpinggou Geohazards |
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| Abstract:In 2017, the Xinmo landslide in Songpinggou, Maoxian County, Sichuan Province, caused serious casualties. In addition to analyzing factors such as rainfall and engineering geology, previous researchers have proposed that the earthquakes also played an important role in the formation of Xinmo landslides. However, there is still a lack of detailed quantitative analysis. In this study, based on the crustal structure and GPS observations in the Longmen Shan area and combined with the co-seismic rupture model of Wenchuan earthquake obtained by USGS, the authors calculated the co-seismic and post-seismic deformation and stress caused by the Wenchuan earthquake by using a viscoelastic layered semi-infinite space model (PSGRN/PSCMP program). The deformation and stress in Songpinggou were analyzed in detail. The results show that the co-seismic rupture of Wenchuan earthquake caused significant surface displacement in Songpinggou area, and the post-seismic deformation continued to strengthen in this area due to the viscoelastic relaxation effect. The eastward and northward displacements caused by the co-seismic rupture of Wenchuan earthquake in Songpinggou area were 26.8~42.3 cm and 7.4~8.0 cm respectively. This area is in the transition zone of vertical displacement rising or descending, with a change of –0.1~1.7 cm. 9 years after the earthquake, on the basis of the co-seismic results, the eastward displacement continued to increase by about 2.5 cm, and the northward displacement increased by 7.4~8.0 cm. The northwestern section of Songpinggou was in the vertical displacement upward zone, while the southeastern section was in the vertical displacement downward zone. The post-seismic deformation caused the average topographic gradient to increase, which has been conducive to the the occurrence of landslide disaster. In view of the uncertain pattern of Songpinggou fault slipping, the coulomb stress changes caused by the Wenchuan earthquake will have different effects on its seismicity. |
| keywords:Longmen Shan Wenchuan earthquake Xinmo landslide post-seismic deformation Coulomb stress |
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