张家口—渤海地震带天津—塘沽段的电性结构及其意义  

Electrical structure of the Tianjin-Tanggu segment of the Zhangjiakou-Bohai seismic belt and its importance

作　　者：高武平[1] 林逸 张文朋[1] 徐新学[2] 闫成国[1] 曹井泉[1] 刘红艳[1] GAO Wuping;LIN Yi;ZHANG Wenpeng;XU Xinxue;YAN Chengguo;CAO Jingquan;LIU Hongyan(Tianjin Earthquake Agency,Tianjin 300201,China;Tianjin North China Geological Exploration Bureau,Tianjin 300170,China)

机构地区：[1]天津市地震局,天津300201 [2]天津华北地质勘察局,天津300170

出　　处：《地震工程学报》2023年第2期410-420,共11页China Earthquake Engineering Journal

基　　金：国家自然科学基金(41772123);天津市科技重大专项与工程(18ZXAQSF00110)联合资助

摘　　要：华北北部的张家口—渤海地震带是一条新生地震断裂带。位于其中段的蓟运河断裂构成了唐山菱形块体的西边界,一直被认为与1979年宁河M 6.9地震密切相关。然而,该区域的深部结构与孕震动力学环境尚未得到有效揭示。大港—玉田大地电磁测深剖面直接穿越宁河M 6.9地震的震中区,大致与张家口—渤海断裂带相垂直。探测结果显示,区域电性结构具有显著的“横向分块、纵向分层”特征。大地电磁测深剖面还揭示了张家口—渤海断裂带中段的海河断裂、汉沽断裂、蓟运河断裂等区域性断裂的深部构造特征,且汉沽断裂可能为切穿地壳的深断裂。深部低阻体边缘的高低阻梯度带与宁河M 6.9地震和汉沽两次M 6.2地震的震中具有良好的对应关系,揭示了研究区中强地震的发生与深部显著高低阻梯度带的发育密切相关。The Zhangjiakou-Bohai seismic belt is a seismic fault zone in the northern part of North China.The Jiyunhe fault zone in its middle segment constitutes the western boundary of the Tangshan rhombus block,and it is considered the seismogenic fault of the Ninghe M 6.9 earthquake in 1979.To effectively reveal the deep structure and seismogenic dynamic environment of this region,we conducted a magnetotelluric sounding profile in the Dagang—Yutian area,which directly crosses the epicenter of the Ninghe M 6.9 earthquake and is almost perpendicular to the Zhangjiakou—Bohai fault zone.Detection results show that the electrical structure in the study area is layered vertically and partitioned horizontally.Additionally,the magnetotelluric sounding profile reveals the deep structural characteristics of some regional faults,i.e.,the Haihe fault,Hangu fault,and Jiyunhe fault in the middle section of the Zhangjiakou—Bohai fault zone,in which the Hangu fault may be a deep fault that runs through the crust.The good correlation between the high and low resistivity gradient zones and the epicenters of the Ninghe M 6.9 earthquake and the other two M 6.2 earthquakes in Hangu suggests that the moderate-strong earthquakes in the study area are closely related to the development of obvious high and low resistivity gradient zones in the deep area.

关 键 词：大地电磁测深 电性结构 张家口—渤海地震带 蓟运河断裂 

分 类 号：P315[天文地球—地震学]