青藏高原东缘汶川地震断层陡坎类型与级联破裂模型

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• 出版年：2010
• 作者：Guihua Yu；Xiwei Xu(徐锡伟）；Yann Klinger；Guilin Diao；Guihua Chen；Xiangdong Feng；Chenxia Li；Ailan Zhu；Renmao Yuan；Tingting Guo；Xinze Sun；Xibin Tan and Yanfeng An
• 单位1：National Center for Active Fault Studies,Institute of Geology
• 语种：中文
• 起始页：26
• 总页数：2
• 刊名：国际地震动态
• 是否内版：否
• 刊频：月刊
• 创刊时间：1971
• 主管单位：中国科学技术协会
• 主办单位：中国地震学会；中国地震局地球物理研究所
• 主编：许绍燮
• 地址：北京市海淀区民族大学南路5号
• 邮编：100081
• 电子信箱：rdws@cea-igp.ac.cn
• 网址：http://www.gjdzdt.org.cn
• 期：6
• 期刊索取号：P263.06 627-3
• 数据库收录：中国核心期刊（遴选）数据库收录期刊；中国学术期刊综合评价数据库统计源期刊；中国期刊全文数据库（CJFD）全文收录期刊；中文科技期刊数据库原文收录期刊
• 核心期刊：中国核心期刊（遴选）数据库收录期刊

摘要

The post-earthquake field investigations reveal that the Mw7. 9 Wenchuanearthquake of 12th May 2008 ruptured three NE-striking imbricate reverse faults and anotherNW-trending reverse fault, along the middle Longmenshan fold-and-thrust belt at the east-ern margin of the Tibetan plateau. The fault-scarp features can be categorized into eightgroups: simple thrust scarp, hanging-wall collapse scarp, simple pressure ridge, dextralpressure ridge, fault-related fold scarp, back-thrust pressure ridge, local normal fault scarpand crocodile-mouth-like scarp. The local normal scarp is first discovered in the reverse-faul-ting earthquakes as ever reported in the world. Field observation indicates that the Wen-chuan earthquake surface rupture is dominated by reverse faulting with a minus right-lateralcomponent, but the relative ratio varies from site to site. Also, the surface ruptures can bedivided, for the first order, into two segments, the Yingxiu and Beichuan segments, corre-sponding to Mw7. 8 and Mw7. 57 events, respectively. The two segments further can be di-vided, for the second order, into four sub-segments in total, which are equivalent to foursub-events of Mw 7. 46, Mw 7. 69, Mw6. 99 and Mw 7. 52, respectively. The fault segmenta-tion, for different orders, shows a cascade-rupturing pattern and can explain why the quaketime of the Wenchuan earthquake was so long as up to 100 second. Aftershock focal mecha-nisms are also used to constrain the fault geometry for the sub-segments, indicating that theseismogenic faults are listric at depth and in general, the fault plane becomes steeper north-ward, which enables the fault to accommodate larger strike-slip motion. This earthquake al-so confirms that the crustal shortening across the Longmenshan fold-and-thrust belt shouldbe responsible for the growth of high topographic relief along the eastern margin of the Ti-betan Plateau.