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宁河地区地震探测结果与桐城断裂浅部结构特征初探
投稿时间:2017-12-27  修订日期:2018-07-20  点此下载全文
引用本文:尹海权,何庆龙,王生文,徐玉健,常明.2018.宁河地区地震探测结果与桐城断裂浅部结构特征初探[J].地质论评,64(5):1132-1140
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作者单位E-mail
尹海权 中国地震局第一监测中心天津300180 742946697@qq.com 
何庆龙 中国地震局第一监测中心天津300180  
王生文 中国地震局第一监测中心天津300180  
徐玉健 中国地震局第一监测中心天津300180  
常明 中国地震局第一监测中心天津300180  
基金项目:本文为全国跨断层场地优化改造项目(编号:15230010)的成果。
中文摘要:桐城断裂是一条对唐山地震有地壳形变反映的活动断裂,是沧县隆起与黄骅凹陷北部的分界线。本次研究在桐城断裂宁河跨断层场地采用浅层地震探测方法,布设了两条近南北向的浅层人工地震物探剖面,获得了两条反映不同深度的高质量叠加时间、深度剖面图,查明了目标断裂的结构特征。本次工作在研究区探测出7条断裂,发现桐城断裂是由多条主断裂和次级断裂组成的断裂带,但本次工作测线布设相对较短且探测深度有限,因此,通过总结相关部门专家和学者在研究区周边的地震探测成果,初步认为断裂带在浅部呈“花状”,并向下呈汇聚趋势。另外,结合前人学者对研究区及周边的钻孔和地层研究工作,通过钻孔地层对比,认为桐城断裂是一条中更新世活动断裂。根据断裂上断点的准确坐标位置以及桐城断裂产状特征,发现宁河跨断层监测场地有效的对F2、F3和F4三条断裂进行了监控,并根据前人对研究区应力应变研究结果,认为宁河跨断层监测场地的巨幅形变反映了F2和F3两条断裂的垂直运动特征。但其形变特征与唐山地震的关系是需要进一步探索的。
中文关键词:桐城断裂  断层形变  浅层地震探测  唐山地震
 
Seismic Survey Result of Ninghe Area and Charactertistics of Tongcheng Fault in Shallow Lateral Structure
NameInstitution
YIN HaiquanFirst Crust Monitoring and Application Center, CEA, Tianjin, 300180
HE QinglongFirst Crust Monitoring and Application Center, CEA, Tianjin, 300180
WANG ShengwenFirst Crust Monitoring and Application Center, CEA, Tianjin, 300180
XU YujianFirst Crust Monitoring and Application Center, CEA, Tianjin, 300180
CHANG MingFirst Crust Monitoring and Application Center, CEA, Tianjin, 300180
Abstract:Objectives:Tongcheng fault is located between the Jixian uplift and the Huanghua depression. Before the Tangshan Ms7.8 earthquake in 1976, the strong crustal deformation of the Tongcheng fault has been observed. We use shallow seismic exploration methods to identify structural features of the Tongcheng fault. It is believed that the large deformation of the Ninghe cross fault monitoring site reflects the vertical motion characteristics of the F2 and F3.Methods:In this study, shallow seismic exploration methods are used in the study area, and two shallow artificial seismic geophysical profiles near the north—south direction are laid. We obtain two high quality superposition time and depth profiles and the structural characteristics of the target fault are identified.Results:According to the stratigraphic characteristics of the study area and the structural characteristics of the Tongcheng fault, the fault is considered to be a mid Pleistocene active fault. It is preliminarily believed that the fault zone is “flower like” in the shallow part and tends to converge downward. Conclusions:The Tongcheng fault is an active fault that reflects the crustal deformation of the Tangshan earthquake and is the dividing line between the Cangxian uplift and the northern part of the Huanghua depression. In this study, two shallow artificial geophysical prospecting sections are arranged at the cross fault site of Ninghe according to the shallow seismic exploration methods. And the structural characteristics of the target fracture are identified on the basis of two high quality superposition time and depth profiles which are reflecting different depths of the Tongcheng fault. In this work, seven faults are detected in the study area. It is found that the Tongcheng fault is a fault zone composed of multiple primary faults and secondary faults. However, the work line is relatively short and the detection depth is limited. Therefore, by summarizing the results of seismic exploration around the study area by experts and scholars from relevant departments, it is preliminarily believed that the fault zone is “flower like” in the shallow part and tends to converge downward. In addition, combined with previous scholars’ research on borehole and stratum in the study area and surrounding areas, through the comparison of borehole strata, Tongcheng fault is considered to be a mid Pleistocene active fault. According to the exact coordinates of the breakpoint on the fault and characteristics of the Tongcheng fault, it is found that F2, F3 and F4 are effectively monitored in the cross fault monitoring sites in Ninghe. According to previous studies on the stress in the study area, the large deformation in Ninghe Field reflects the vertical movement characteristics of two faults F2 and F3. However, the relationship between its deformation characteristics and the Tangshan earthquake needs further exploration.
keywords:Tongcheng Fault  Fault deformation  High-resolution seismic reflection profiling  Tangshan earthquake
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