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《Earth Science Frontiers》 2009-03
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The striations character of M_s 8.0 Wenchuan Earthquake and its application research

Zhang Junlong Insititute of Earthquake Science,China Earthquake Administration,Beijing 100036,China  
On May 12th,2008,a great Ms 8.0 earthquake occurred in Wenchuan County,Sichuan Province.The Beichuan-Yingxiu fault extending about 220 km characterized by dextral strike-slip faulting is one of the three main seismogenic faults along the Longmenshan Fault zone,and its activity is much more important than the other two.The major shock had induced clear striations presenting at some local places along the rupture of the Beichuan-Yingxiu fault,the location and size of the striations may be the surface response to the peak value of the deep rupture.Based on the stress field reflected by the striations and on the relationship between displacement and surface rupture length,the Beichuan-Yingxiu rupture zone are able to be subdivided into three segments,namely the Hongkou subsection,the Beichuan subsection and the Nanba subsection.Among them,Hongkou subsection extends 22-45 km,with coseismic displacement of 4.5 m with σ1 stress in the direction of NWW-NW,which had undergone at least three phases of activation.It is indicated that the phase Ⅲ is the most intensive reverse faulting which reconstructs the phaseⅠandⅡ dextral strike slip activity,which all are controlled by the main shock.The Beichuan subsection extends 90-100 km,with coseismic displacement of 3.5 m,and σ1 stress in the direction of NWW and is approximately horizontal,and its intensity is weaker than the phase III of Hongkou.The Nanba subsection extends 35-50 km,with coseismic displacement of 2.5 m and σ1 stress in the direction of NWW characterized by nearly horizontal compression.The σ1 azimuth is 180°different from those of the south and middle segments,and its intensity is similar to that of the phaseⅠandⅡ of the south segment.
【Fund】: 国家重点基础研究发展计划“973”项目(2008C13425701);; 中国地震局基本科研业务专项(02076902-07);; 中国地震局地震科学联合基金课题“华北克拉通东北部地震构造动力环境研究”
【CateGory Index】: P542.3;P315.2
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