地震地质 ›› 2008, Vol. 30 ›› Issue (3): 630-643.

• 研究论文 • 上一篇    下一篇

汶川MS8.0地震发震断裂大地震原地重复现象初析

冉勇康, 陈立春, 陈桂华, 尹金辉, 陈杰, 宫会玲, 史翔, 李陈侠   

  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
  • 收稿日期:2008-08-05 修回日期:2008-08-10 出版日期:2008-09-18 发布日期:2009-11-27
  • 作者简介:冉勇康,男,1955年生,1979年毕业于北京大学地貌专业,1997年在中国地震局地质研究所获得博士学位,研究员,博士生导师,主要从事活动构造、古地震和工程地震等方面的研究,电话:010-62009213,E-mail:ykran@263.net.
  • 基金资助:
    国家自然科学基金(40841007);国家重点基础研究发展计划项目(2004CB418401);中国地震局汶川8.0级地震应急科学考察项目共同资助

PRIMARY ANALYSES OF IN-SITU RECURRENCE OF LARGE EARTHQUAKE ALONG SEISMOGENIC FAULT OF THE MS8.0 WENCHUAN EARTHQUAKE

RAN Yong-kang, CHEN Li-chun, CHEN Gui-hua, YIN Jin-hui, CHEN Jie, GONG Hui-ling, SHI Xiang, LI Chen-xia   

  1. National Centre of Active Fault Studies, Institute of Geology, China Earthquake Administration, Beijing 100029, China
  • Received:2008-08-05 Revised:2008-08-10 Online:2008-09-18 Published:2009-11-27

摘要: 在历史记录中,成都和龙门山地区没有发生过类似汶川MS8.0地震强度的地震。那么,在地质记录中是否会存在类似震级的古地震遗迹?作者分别在中央和前山断裂中段的地表破裂带上4个地点开挖了探槽4个和剖面1个,并进行了断错地貌面的实测。文中从几个地点新老地貌面累计变形量、探槽揭露的古地震遗迹等方面讨论汶川地震发震断裂大地震原地重复现象存在的基本事实。结果表明:无论在中央断裂的小鱼洞、擂鼓镇还是前山断裂的白鹿镇、汉旺等地,汶川5.12地震之后Ⅱ级阶地断层陡坎与Ⅰ级阶地陡坎高度基本呈倍数关系,探槽揭露Ⅱ级阶地标志地层(黄砂土层)在断裂两盘的位差也是5.12地震的约2倍,显示在龙门山地区区域Ⅱ级阶地形成之后,汶川5.12地震发生之前,存在一次与汶川MS8.0地震地表变形规模相当的地震事件。

关键词: 汶川MS8.0地震, 龙门山, 古地震, 大地震重复

Abstract: In the historical rocords,there have been no comparable earthquakes with the May 12 Wenchuan earthquake in Chengdu and Longmenshan mountain region.Then,whether the ancient earthquake traces with comparable magnitude in the geological records can be found has become an important scientific issue.The authors and other members of Wenchuan earthquake geological investigation team did fieldwork in the earthquake region for more than one month.Four trenches and one geologic section were excavated along the middle segment of surface faulting of both the central fault and the mountain front fault.And geomorphologic surfaces of deformation were measured.In this paper,we discuss the fact that there is prehistory large earthquake along the seismogenic fault of Wenchuan earthquake from analyzing the accumulated deformation of old and young fault scarps or geomorphologic surfaces,trenching,and comparing the activities of related faults and so on.The result shows that whether at Xiaoyudong,Leigu located on the central fault or Bailu,Hanwang on the mountain front fault,or at other places along the surface faulting of the the Wenchuan earthquake,the height of the fault scarp on the second terrace has a multiple relation with that on the first terrace after the Wenchuan earthquake.The 4 trenches reveal that the dislocation of the marker strata of the second terrace on both sides of fault is twice of that of the Wenchuan earthquake,which shows that there was an earthquake event with the same scale of surface deformation of this MS8.0 Wenchuan earthquake between the formation time of the second terrace in Lomhmenshan area and the May 12 Wenhucan earthquake.

Key words: MS8.0 Wenchuan Earthquake, Longmenshan Mountains, paleoearthquake, earthquake recurrence

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