A shallow aftershock sequence in the north-eastern end of the Wenchuan earthquake aftershock zone

查看全文 作　　者：Luo [1,2]Yan;Ni [1]SiDao;Zeng [1]XiangFang;Zheng [3]Yong;Chen [2]QiFu;Chen [2]Yong

机构地区：[1]Univ Sci & Technol China, Sch Earth & Space Sci, Hefei 230026, Peoples R China;[2]China Earthquake Adm, Inst Earthquake Sci, Beijing 100036, Peoples R China;[3]Chinese Acad Sci, Inst Geodesy & Geophys, Wuhan 430077, Peoples R China;

出　　处：《Science China Earth Sciences》索引2010年第53卷第11期,共10页

基　　金：supported by Institute of Earthquake Science China Earthquake Adminis-trator (Grant No.02092410);Knowledge Innovation Program of the Chi-nese Academy of Sciences (Grant Nos.KZCX2-YW-116-1, KZCX2-YW-142);National Natural Science Foundation of China (Grant Nos.40674027,40604004);Earthquake Hazard Reduction Program (Grant No.200808078) 摘　　要：Previous studies show that mature faults are filled with fault gouge in the shallow part and thus cannot accumulate enough strain energy for earthquakes. Therefore most earthquakes are deeper than 5 km, except those events occurring on new faults or in intact rocks. From field observation, Wenchuan earthquake is found to rupture the free surface about 200 km, but the rupture may extend underground much further from teleseismic body waves inversion and aftershocks distribution. In the northeastern end of the rupture zone, deep rupture may induce stress increase near the free surface, and trigger shallow earthquakes. An Ms 5.7 aftershock occurred at Qingchuan, northeast end of Wenchuan earthquake fault on July 24, 2008, featuring thrust mechanism with a 3 km source centroid depth. The shallow focal depth is confirmed with the sPL phase recorded at station L0205. As Rayleigh wave is well only developed for source depth less than 1/5 of epicentral distance, the observed large amplitude of Rg at a distance of 15 km implied depth of 3 km or less. Dozens of aftershocks' sPL waveforms are also analyzed to confirm the source depths less than 3 km. On the other hand, no surface ruptures are found by geological survey or InSAR studies. It is strongly suggested that these aftershock sequences initiate fresh rupture in intact rocks triggered by stress increase from the deep co-seismic rupture of the Wenchuan mainshock. 关键词：WENCHUAN EARTHQUAKE SHALLOW EARTHQUAKE FOCAL depth wave modeling

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A shallow aftershock sequence in the north-eastern end of the Wenchuan earthquake aftershock zone

参考文献(40)

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耦合文献(1808)

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