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Title:: Seismic Distribution and Tectonic Significance of the Northern Segment of the Tangshan Fault

Author(s):: ZHANG Suxin; BIAN Qingkai; ZHANG Ziguang; WANG Xiaoshan; CAO Jun; LI Yongqing; (Hebei Earthquake Agency,Shijiazhuang 050021,Hebei,China)

Keywords:: northern segment of the Tangshan fault; temporal and spatial evolution; tectonic distribution; stress state distribution; tectonic significance

摘要:: 自1976年唐山7.8级地震后40多年的余震时空图像演化显示,老震区余震的空间分布呈现出不均匀特征,尤其是1996年以来,老震区震中附近几乎没有4级以上地震发生,而在主震发震断裂(唐山断裂)北段赵各庄至榛子镇沿线形成了一个新的NW向4级以上地震密集区,2012年5.2级、2010年4.8级地震就发生在该区域。针对1996年前、后唐山地震余震空间分布图像对比所呈现的特点,通过对余震空间分布、前人研究成果、断裂带应力状态以及现场考察等的研究,综合分析唐山断裂北段地震分布特征及其构造意义,认为赵各庄到榛子镇的旧断裂存在新活动特征,未来中等强度以上地震危险区可能是古冶及其邻区。

Abstract:: The spatial evolution of 40 years after the Tangshan M7.8 earthquake shows that the aftershock distribution is uneven.There was no M4 earthquake near the epicenter region since 1996.The M4 earthquake has formed a new dense area near Zhaogezhuang to Zhenzizhen in the eastern end of the main seismic fault,and the M5.2 earthquake in 2012,the M4.8 earthquake in 2010 occurred in this region.In view of these characteristics shown in the aftershock spatial distribution images before 1996,through the aftershock spatial distribution,previous research results,stress status of the fault zone,and site inspection and other works,we comprehensively analyze the seismic distribution characteristics and tectonic significance of the northern segment of the Tangshan fault.At the same time,the old faults from Zhaogezhuang to Zhenzi Town have new activity characteristics.In the future,moderate earthquake may occur in Guye and its adjacent areas.