The Origin of the 2008 Wenchuan Earthquake Determined by the Analysis on the Active Longmenshan Nappe in Terms of Rockmass Mechanics

查看全文 作　　者：YAN [1,2]Zhixin;MA [1]Guozhe;YUAN [1,2]Binxiang;NIU [3]Fujun

机构地区：[1]School of Civil Engineering and Mechanics,Lanzhou University,222 South Tianshui Road,Lanzhou 730000,China;[2]Key Laboratory of Mechanics on Western Disaster and Environment Ministry of Education,China,222 South Tianshui Road,Lanzhou 730000,China;[3]Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academic of Science,320 West Donggang Road,Lanzhou 73oooo,China

出　　处：《Journal of Mountain Science》索引2012年第9卷第3期,共8页

摘　　要：On 12 May 2008, the magnitude 8.0 Wenchuan Earthquake occurred along the Longmen Shan nappe, Sichuan, China. This devastating earthquake led to a heavy death toll of greater than 80,000. The seismic origin of this earthquake is currently hotly debated. We suppose that it is a special type of intraplate earthquake called an active-nappe-type earthquake. Using a holistic methodology, incorporating rockmass structure cybernetics and Byerlee's law, we present a comprehensive study on the geological origin of macroseisms in the Longmen Shan area and the seismic origin of the 2008 Wenchuan earthquake. Previous studies of neotectonic activity indicate that the Longmen Shan nappe moves at a rate of 1~3 mm/yr, due to horizontal compressive stress from the Tibetan Plateau. The difference between movement rates in the Bayankala block, Longmen Shan nappe and Sichuan Basin cause slow shear stress and strain accumulation in the Longmen Shan nappe. It is exhibited a relatively simple linear relations for the shear strength and the buried depth of the structural planes, and the detachment layer of the nappe has a higher shearing-sliding strength compared to the overlying fault planes and the underlying ductile shear belts, thus making it more prone to stick-slip deformation. Therefore, the detachment layer was the main section responsible for the Wenchuan earthquake. The initial rupture burst in the detachment layer under the Yingxiu-Beichuan fault, the rupture area nearly 1.4454 × 104 km2,encompassed the cross point of the Yingxiu and the Anxian-Guanxian faults with the detachment layer, then caused the Yingxiu-Beichuan and Anxian-Guanxian faults took an active part in this earthquake, so this earthquake might consist of three chain-like earthquake stages, totally increasing the duration of this earthquake an unusually large amount, to 120 s. The focal depth spanned range of 10-20km,consistent with the observed result of this focal depth by several agencies. 关键词：龙门山地区岩体力学分析推覆构造大地震汶川韧性剪切带测定起源

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The Origin of the 2008 Wenchuan Earthquake Determined by the Analysis on the Active Longmenshan Nappe in Terms of Rockmass Mechanics

参考文献(35)

引证文献(2)

耦合文献(865)

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