A special issue on the great 12 May 2008 Wenchuan earthquake (Mw7.9): Observations and unanswered questions
A special issue on the great 12 May 2008 Wenchuan earthquake (Mw7.9): Observations and unanswered questions
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DOI：
10.1016/j.tecto.2010.05.019
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发表时间：
2010-08
期刊：
影响因子：
2.9
通讯作者：
A. Yin
中科院分区：
文献类型：
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作者：
A. Yin
2008年5月12日的汶川地震（Mw 7.9）破坏了活动的龙门山冲断带，该冲断带将青藏高原东缘与四川盆地相结合（图1）（Burchfiel等人，2008年）。这场毁灭性地震的初步观测结果在几篇专注于同震滑动和地震断层几何学的短文中报道（例如，Wang等人，2008年; Xu等人，2009; Lin等人，2009; Liu-Zeng等人，2009; Hubbard和Shaw，2009; Shen等人，2009; Feng等人，2010年）。随后的工作解决了水库是否引发了地震的问题（Ge等人，2009年），如果西藏东部的软弱中地壳和下地壳控制了地震断裂带的位置（Xu et al.，2010 a; Zhang等人，2010年a）。早期的研究已经确立了汶川地震的一些基本事实。首先，主震破坏了龙门山冲断带东部的两条北西向断裂：西北侧的北川-映秀断裂（长约230 km）和东南侧的彭关断裂（长约110 km）（图2）。第二，同震滑动在彭官断裂上以逆冲运动为主，在北川-映秀断裂上以右旋和逆冲混合运动为主。北川-映秀断裂的同震滑动向北东方向发生了系统性的变化，从以浅倾破裂面为主的逆冲运动到沿沿着断层走向的近纯右滑运动。第三，龙门山冲断带位于沿着一个地壳尺度的边界上，该边界介于西北部较年轻、可能较弱的三叠纪松潘-甘孜地块和东南部较古老、因而较强的华南地块之间。本期共收录了22篇关于汶川地震早期报道的论文。该卷包括以下六个主题：（1）同震滑动，（2）由汶川地震和西藏东部近期地震活动引起的静态库仑应力的演化，（3）晚第四纪地震活动的重现时间，（4）龙门山逆冲带的构造背景和结构框架，（5）青藏高原东部的岩石圈结构，（6）在不同的时间尺度上龙门山逆冲带的折返和构造之间的相互作用。现将本期论文的主要观点作一综述，并就汶川地震与青藏高原东部构造演化的一些突出问题作一概述。
The 12 May 2008 Wenchuan earthquake (Mw 7.9) ruptured the active Longmen Shan thrust belt bounding the eastern margin of the Tibetan plateau against the Sichuan basin (Fig. 1)(Burchfiel et al., 2008). Initial observations of this devastating earthquake were reported in several short papers focusing on coseismic slip and earthquake-fault geometry (eg, Wang et al., 2008; Xu et al., 2009; Lin et al., 2009; Liu-Zeng et al., 2009; Hubbard and Shaw, 2009; Shen et al., 2009; Feng et al., 2010). Subsequent work has addressed the questions of whether reservoir had triggered the earthquake (Ge et al., 2009) and if a weak middle and lower crust in eastern Tibet had controlled the location of the earthquake fault zone (Xu et al., 2010a; Zhang et al., 2010a). The early studies have established some of the basic facts about the Wenchuan earthquake. First, the main shock ruptured two northwest-dipping faults in the eastern part of the Longmen Shan thrust belt: the sub-parallel Beichuan–Yingxiu fault (∼ 230 km) in the northwest and the Pengguan fault (∼ 110 km) in the southeast (Fig. 2). Second, coseismic slip was accommodated dominantly by thrust motion on the Pengguan fault and by mixed right-slip and thrust motion on the Beichuan–Yingxiu fault. Specifically, coseismic slip on the Beichuan–Yingxiu fault changes systematically northeastward, from dominant thrust motion on shallowdipping rupture planes to nearly pure right-slip motion along fault strike. Third, the Longmen Shan thrust belt lies along a crustal-scale boundary between the younger and possibly weaker Triassic Songpan–Ganze terrane in the northwest from the much older and thus stronger South China block in the southeast. The current issue collects a total of 22 papers that expand greatly on the early reports of the Wenchuan earthquake. The volume covers the following six subjects:(1) coseismic slip,(2) evolution of static Coulomb stresses induced by the Wenchuan earthquake and recent seismicity in eastern Tibet,(3) recurrence times of late Quaternary seismicity,(4) tectonic setting and structural framework of the Longmen Shan thrust belt that hosts the Wenchuan earthquake fault,(5) lithospheric structure of the eastern Tibetan plateau, and (6) interplay between exhumation and tectonics across the Longmen Shan thrust belt at various time scales. Below I summarize the main points of the papers presented in this issue and outline some of the outstanding issues with regard to the Wenchuan earthquake and the tectonic evolution of the eastern Tibetan plateau.