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Title:: Analysis of Paleoseismic Events of the Dahuzhuang Trench at the Xiadian Fault

作者:: 邓梅¹; 沈军^1; 李西²; 祁高¹; 戴训也¹; 王昌盛¹; 刘泽众¹; (1.防灾科技学院,河北燕郊 065201; 2.云南省地震局,云南昆明 650224)

Author(s):: DENG Mei¹; SHEN Jun¹; LI Xi²; QI Gao¹; DAI Xunye¹; WANG Changsheng¹; LIU Zezhong¹; (1. Institute of Disaster Prevention,Yanjiao 065201,Hebei,China)(2. Yunnan Earthquake Agency,Kunming 650224,Yunnan,China)

Keywords:: the Xiadian fault; paleaoseismic event; collapse wedge; sand liquefaction; symbol layers

摘要:: 夏垫断裂是北京平原区内1条极为重要的隐伏活动断裂,同时也是1679年三河—平谷M_S8.0地震的发震断层。为获取该断裂完整的古地震序列,主要开展了2方面工作:①以大胡庄探槽原始资料为基础,重新对探槽进行了解译,共识别出3个埋藏古土壤,6个崩积楔和1次砂土液化现象; ②结合该断裂其它部位探槽揭示的古地震事件,通过对比各探槽标志性地层,建立不同探槽中古地震事件在同一时间轴上的联系,得到夏垫断裂完整的古地震序列。结果表明:距今31 ka以来,夏垫断裂共发生过11次古地震事件,古地震平均复发间隔约为2.8 ka,但距今25～15 ka存在1个古地震丛集期,丛集期内共发生5次强震,平均复发间隔约为2.0 ka,反映出夏垫断裂活动性存在阶段性的差异。

Abstract:: The Xiadian fault is an important buried active fault located in the Beijing plain. It is also the seismogenic fault of the Sanhe-Pinggu M_S8.0 earthquake occurred in 1679. In order to obtain the complete paleoseismic sequence of the fault,the following two aspects are carried out. First,we reinterpret the Dahuzhuang trench based on the origin trench datum and reveal three paleosol,six collapse wedges and one sand liquefaction. Second,combined with the events revealed by the trenches in other parts of the fault,we established the relationship between the seismic events of different trenches at the same time axis. Then,we get intact paleoseismic sequence of the Xiadian fault. The results show that the Xiadian fault has occurred 11 paleoseismic events(including the 1679 earthquake)since 31 ka and the average recurrence interval of earthquake was 2.82 ka. Meanwhile,there were five strong earthquakes from 25 ka to 15 ka and the average recurrence interval was 2 ka. It reflects that the activity of the Xiadian fault exists differences at different stages.