地震地质 ›› 2015, Vol. 37 ›› Issue (2): 413-429.DOI: 10.3969/j.issn.0253-4967.2015.02.006

• 研究论文 • 上一篇    下一篇

1739年平罗8级地震发震构造

雷启云1,2, 柴炽章2, 杜鹏2, 俞晶星1, 王银2, 谢晓峰2   

  1. 1. 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029;
    2. 宁夏回族自治区地震局, 银川 750001
  • 收稿日期:2014-03-11 修回日期:2014-07-16 出版日期:2015-06-20 发布日期:2015-08-19
  • 作者简介:雷启云,1981年生,2005年于兰州大学获地质工程专业硕士学位,高级工程师,现为中国地震局地质研究所在读博士研究生,主要从事活动构造与新构造研究,电话:0951-5068227,E-mail:leiqy624@163.com。
  • 基金资助:

    国家自然科学基金(41202158)、地震行业科研专项(201308012)、地震科技星火计划(XH14052)和全国地震重点监视防御区活断层危险性评价项目(1520930027)共同资助。

THE SEISMOGENIC STRUCTURE OF THE M8.0 PINGLUO EARTHQUAKE IN 1739

LEI Qi-yun1,2, CHAI Chi-zhang2, DU Peng2, YU Jing-xing1, WANG Yin2, XIE Xiao-feng2   

  1. 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;
    2. Earthquake Administration of Ningxia Hui Autonomous Region, Yinchuan 750001, China
  • Received:2014-03-11 Revised:2014-07-16 Online:2015-06-20 Published:2015-08-19

摘要:

1739年平罗8级地震是银川平原上有史以来发生的最大一次破坏性地震。关于该地震的发震构造尚有不同认识。在近年获得的探槽、钻探、浅层地震勘探等资料的基础上, 对红果子长城及周边台地的地震位错现象开展了调查和详细测量, 并再次探讨了1739年平罗8级地震的发震构造。结果表明, 贺兰山东麓断裂的最后一次破裂事件发生在距今600~700a之后, 修筑于500a前的明长城被错断。尽管银川隐伏断裂的展布和极震区相吻合, 但该断裂向北终止于姚伏镇, 全新世活动段长度不超过36km, 其最后一次地表破裂事件发生在距今3 400a之前不久, 银川隐伏断裂在1739年平罗8级地震中没有发生地表破裂。断裂附近生长地层的发育和地层无同步变形的事实表明, 银川隐伏断裂并没有发生被松散层吸收而未抵达地表的破裂。因此, 1739年8级地震的发震构造是贺兰山东麓断裂而非银川隐伏断裂, 2条断裂没有发生同步牵连活动。平罗8级地震的发震构造和极震区分布的异位, 可能与断裂倾向、地下水位深度、盆地结构、松散地层厚度、居民聚集等因素有关, 这类由盆地边界铲形断裂发震而极震区向盆地中心偏移的现象, 应在类似地区的抗震设防中予以重视。

关键词: 贺兰山东麓断裂, 平罗地震, 发震构造, 银川隐伏断裂, 长城错动

Abstract:

The 1739 M8.0 Pingluo earthquake is the largest destructive earthquake occurring on the Yinchuan plain in history. However, there are different understandings about the seismogenic structure of this earthquake. In this paper, we re-evaluate the seismogenic structure of the 1739 M8.0 Pingluo earthquake after our investigation and detailed measurement of the seismic dislocations on the Great Wall and the surrounding tableland, and also the latest results of trenching, drilling, and shallow seismic exploration are considered as well. The results show that the latest rupture event of the Helanshan piedmont fault occurred after 600~700a BP, the Great Wall built in Ming Dynasty about 500 years ago was faulted by Helanshan piedmont fault. Although the distribution of Yinchuan buried fault coincides much with the distribution of the meizoseismal area, the fault's northward extending stopped at Yaofu town, and its Holocene active segment is less than 36km in length. The latest surface rupture occurred shortly before 3400a BP. The 1739 Pingluo earthquake did not rupture the ground surface along the Yinchuan buried fault. The presence of growth strata and the non-synchronous deformation of strata near the fault demonstrate that Yinchuan buried fault did not rupture at all or there was rupture but absorbed by the loose layers in the 1739 Pingluo earthquake. Therefore, the Helanshan piedmont fault is the seismogenic structure of the 1739 M8 Pingluo earthquake, rather than the Yinchuan buried fault, and there is no synchronous rupture between two faults. The difference of location between the seismogenic structures and the meizoseismal area of the Pingluo M8 earthquake may be caused by the factors, such as fault dip, groundwater depth, basin structure, loose formations, the degree of residents gathering, so on. The phenomenon that the meizoseismal area shifts to the center of the basin of earthquake generated by faulting of a listric fault on the boundary of the basin should be paid more attention to in seismic fortification in similar areas.

Key words: Helanshan piedmont fault, Pingluo earthquake, seismogenic structure, Yinchuan buried fault, dislocation of the Great Wall

中图分类号: