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Journal: |
Chinese Journal of Geophysics 2009 No.2
clicks:748 |
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Title:
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Author:
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FU Bi-Hong; SHI Pi-Long; WANG Ping; LI Qi; KONG Ping; ZHENG Guo-Dong |
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Adress: |
Key Laboratory of Earth′s Deep Interior, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China |
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Abstract:
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The NE-trending Yingxiu-Beichuan and Guanxian-Anxian faults in the Longmen Shan fault zone are responsible for the 12 May 2008 MS8.0 Wenchuan earthquake. Based on the interpretation of post-quake high-resolution remote sensing imagery and field geologic observations, the geometry and kinematics of co-seismic surface rupture as well as the seismic and geologic hazards along the Beichuan segment between Leigu Town and Qushan Town, Beichuan County, are analyzed in detail. Results indicate that surface deformation appears as an oblique thrusting with near equal vertical and right-lateral displacements ranged from 2 to 10 m, in which the largest displacement occurred along this segment in the Yingxiu-Beichuan fault. A notable distribution feature of geologic disasters and building damages induced by this earthquake shows strong hanging wall effects across the surface rupture zone: the highest density of landslides, rock falls, debris flows and building damages occurred on the northwest (hanging wall) side of the fault, but few geologic disasters developed on the southeast (foot wall) side of the fault. These effects are caused directly by the asymmetric fault geometry and the stress interaction between the fault motion and free surface of the slopes. Other factors such as material heterogeneity and spatial variation in frictional properties along the fault strike may further affect the rupture and slip patterns of oblique thrust faulting with a right-lateral strike-slip component.
From view of disaster mitigation, the geometry and kinematics of surface rupture zone associated with the MS8.0 Wenchuan earthquake also taught a realistic lesson to how to mitigate potential seismic and geologic disasters associated with future great earthquakes in highly populated region through pre-earthquake analysis and evaluation of active faults using remote sensing technique combined with field reconnaissance. |
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