Analysis of characteristics of geological hazards by "4·20" Lushan earthquake in Sichuan,China
Analysis of characteristics of geological hazards by "4·20" Lushan earthquake in Sichuan,China
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发表时间：
2013
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通讯作者：
Huang Run-qiu
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作者：
Huang Run-qiu
“4·20”芦山地震是继“5·12”汶川地震后，龙门山断裂带发生的又一强震。芦山地震引发有害地质灾害1800余处，较震前增加14%。地质灾害高发区位于Ⅷ、Ⅸ级烈度区，包括龙门—宝胜—太平—双石、大溪-灵关-中坝-牟平。地质灾害主要类型有浅层滑坡、崩塌、落石，特别是塌陷体。其破坏模式为振动-断裂-滑动、振动-断裂-散落和振动-偏心滚动。地震地质灾害除地震触发作用外，还受地形陡峭、地形和高程放大效应的突出特点控制。岩性薄弱，地震强度大。风化卸荷岩体是地质灾害的物质基础。根据现场调查，许多地质灾害是由地震人员伤亡直接造成的。地震崩塌落石危险区范围为Dmax=(0.7~1.3)Hmax，落石移动距离为dmax≈1.1404Hmax+6.42。这与汶川地震崩塌的研究结果一致。
The "4·20" Lushan earthquake is another strong earthquake occurred in the Longmenshan fault zone after the "5·12" Wenchuan earthquake.The Lushan earthquake triggered more than 1800 harmful geological hazards,which increased by 14 percent than before the earthquake.The areas where geological hazards occur high frequently are located in that with Ⅷ and Ⅸ grade intensity,including Longmen-Baosheng-Taiping-Shuangshi and Daxi-Lingguan-Zhongba-Muping.The main types of geological hazards include shallow landslides and collapses,rockfall,particularly the collapsed bodies.Their failure mode is vibration-fracturing-sliding,vibration-fracturing-scattered and vibration-eccentric rolling.Besides the earthquake triggering effect the earthquake geological hazards are controlled by the prominent characteristics of steep topography,terrain and elevation amplification effect.And the weak lithology and the strongly weathered unloading rock mass are the material basis of geological hazards.According to the field survey,many geological hazards are directly caused by the earthquake casualties.The range of the earthquake collapse and rockfall danger zone is Dmax=(0.7~1.3)Hmax and the rockfall movement distance is dmax≈1.1404Hmax+6.42.These are consistent with the research results of the Wenchuan earthquake's collapse.