地震地质 ›› 2008, Vol. 30 ›› Issue (4): 1023-1032.

• 地震地表破裂带 • 上一篇    下一篇

从两个地表破裂点的几何学与运动学特征分析汶川地震的破裂方式

魏占玉1, 何宏林1, 董绍鹏1, 陈杰1, 高翔1, 孙海清2, 嘉世旭3, 王世元4   

  1. 1. 中国地震局地质研究所, 国家地震活动断层研究中心, 北京, 100029;
    2. 浙江省地震局, 杭州, 310013;
    3. 中国地震局地球物理勘探中心, 郑州, 450002;
    4. 四川省地震局, 成都, 610041
  • 收稿日期:2008-07-21 修回日期:2008-12-02 出版日期:2008-12-18 发布日期:2009-11-27
  • 作者简介:魏占玉,男,1981年生,2000年毕业于中国矿业大学地理信息系统应用专业,2004年硕士毕业于中国矿业大学(北京)地球探测与信息技术专业,现为中国地震局地质研究所构造地质专业博士研究生,研究方向为活动构造,电话:13811420178,E-mail:weizhanyu@gmail.com.
  • 基金资助:
    中国地震局汶川8.0级地震应急科学考察项目资助

RUPTURE ANALYSIS OF THE WENCHUAN EARTHQUAKE AT TWO OBSERVATION STATIONS BY GEOMETRY AND KINEMATICS

WEI Zhan-yu1, HE Hong-lin1, DONG Shao-peng1, CHEN Jie1, GAO Xiang1, SUN Hai-qing2, JIA Shi-xu3, WANG Shi-yuan4   

  1. 1. National Center for Active Fault Studies, Institute of Geology, China Earthquake Administration, Beijing 100029, China ;
    2. Earthquake Administration of Zhejiang Province, Hangzhou 310013, China;
    3. Geophysical Exploration Center, China Earthquake Administration, Zhengzhou 450002, China;
    4. Earthquake Administration of Sichuan Province, Chengdu 610041, China
  • Received:2008-07-21 Revised:2008-12-02 Online:2008-12-18 Published:2009-11-27

摘要: 汶川MS 8.0地震的地表破裂出现在中央和前山2条断裂上,分别形成了235km和72km长的地震地表破裂带,而且地表破裂表现出复杂的几何学和运动学特征。文中选取了中央断裂上虹口乡桐麻坎和擂鼓镇石岩村2个地表破裂点,通过几何学与运动学特征分析其地表破裂方式。桐麻坎的白沙河河床上4条右阶斜列的主破裂西南侧发育了一条反冲断层坎,精细地形测量反映出了破裂带内的断块特征与破裂过程中的地表掀斜;擂鼓镇石岩村逆冲破裂前缘的2条次级断层形成叠瓦式结构,地貌上表现为挠曲和其上部的地震鼓包。该两点地表破裂的几何学、运动学特征分析表明,本次地震在龙门山中央断裂上的破裂方式以逆冲为主,兼有右旋走滑。这一结果与美国地质调查局、哈佛大学和中国地震台网中心提供的震源机制解基本一致。此外,桐麻坎和石岩村横切破裂带的地形剖面显示出不同的地表掀斜方向,这种不一致主要由于前者位于断裂挠曲后缘,后者位于断裂挠曲前缘。

关键词: 汶川地震, 龙门山断裂, 断层反坎, 地震鼓包, 地表破裂

Abstract: Surface ruptures of the MS 8.0 Wenchuan earthquake are distributed mainly on the Longmenshan central fault and front-range fault,extending 235km and 72km,respectively.The ruptures exhibit complicated characters in geometry and kinematics.On the riverbed of Baisha river,a backthrust scarp was formed in the southwest of the major fault that comprises four right-step sub-faults,and precise topographical measurement shows a kinematic character of fault block and surface tilting in the rupture process;In Shiyan village,the master fault and the secondary fault formed an imbricate structure,and show as flexures and earthquake swells on ground surface.We analyzed the ruptures at Tongmakan village and Shiyan village,both locating on the central fault,by geometry and kinematics,and the results indicate that the earthquake rupturing along the central fault is mainly characterized by thrusting associated with right-lateral strike-slipping.This result is consistent with the focal-mechanism solutions which are promulgated by U.S.Geological Survey,Harvard University and China Earthquake Networks Center.In addition,the profiles of Tongmakan and Shiyan display different tilting directions,and the reason is that the former locates at the trailing edge of the fault,while the latter in the leading edge of fault.

Key words: Wenchuan earthquake, Longmenshan Fault, backthrust scarp, earthquake swell, surface rupture

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