DEEP STRUCTURE IN SHIJIAZHUANG AND THE VICINITY BY MAGNETOTELLURICS

doi:10.3969/j.issn.0253-4967.2011.04.015

Abstract

Abstract:

The Shijiazhuang City in Hebei Province lies at the junction between the Taihangshan uplift in the west and the Jizhong depression of North China in the east,abutting the front-range fault zone of the Taihangshan in the west.The Xingtai M7.2 earthquake of March 1966 occurred southeast to this area.In October 2010,a broadband magnetelluric(MT)survey was conducted in the Shijiazhuang City and adjacent regions to probe the deep structure.The 167km-long MT profile began from the Niangziguan town,extended southeastward through southern Shijiazhuang City,and terminated at Wangchang town of Jixian county.MT data were collected at 64 sites along this profile.In MT data processing,in addition to the remote reference and robust techniques,the multi-point and multi-frequency tensor decomposition was employed to determine the regional electric strike,and the NLCG 2D inversion was performed on TE and TM data.The result shows that a combination of an east-dipping low-angle normal fault in the shallow subsurface and a steep electric boundary at depth characterizes the deep structure beneath the study area.The electric structures in the shallow crust(above 10km)and deep crust(below 10km)seem to be independent.The Jinxian Fault and Xinhe Fault extend to a depth of less than～7km.High conductivity layer(HCL) is present below the depth of 10km between the front-range fault zone of the Taihangshan and the Xinhe Fault.There is a low resistivity boundary zone below the HCL and it cuts through the Moho.The hypocenter of the 1966 Xingtai Baichikou strong aftershock is located at the linkage between Xinhe Fault and deep electrical boundary,and on its top is a high resistance body and below it is the high conductivity layer(HCL).The HCL and the deep low resistivity boundary zone below the HCL are a channel of deep thermal upwelling and elastic energy migration.The 1966 Xingtai earthquake swarm is closely related to the deep material damping.

Key words: the piedmont fault zone of Taihangshan, Jizhong depression, deep electrical structure, high conductivity layer

摘要：

石家庄位于太行山隆起带和华北平原冀中坳陷盆地接触区,西邻太行山山前断裂带,1966年在其东南曾发生邢台7.2级强震。为研究该区的深部构造背景,并为分析地震活动性趋势提供基础资料,2010年10月采用宽频带大地电磁法对该区的深部结构进行探测研究。大地电磁剖面穿过石家庄南侧区域,长约167km,获得了64个测点数据。采用远参考和Roubst技术进行数据处理,使用多点、多频率GB张量分解方法计算分析区域的电性走向,使用NLCG二维反演方法对TE和TM模式进行联合反演,获得深部电性结构。太行山山前断裂带浅部东倾的低角度滑脱断层和深部陡立西倾的电性边界带,构成了太行山隆起带和华北平原冀中坳陷接触区的深、浅构造的组合形态; 太行山山前断裂带东侧深(10km以下)、浅部(10km以上)结构具有相互独立性,冀中坳陷内的晋县断裂、新和断裂延伸深度不超过10km; 邢台百尺口6.2级强余震震源位于上陡、下缓的新河断裂和其下隐伏的深部电性差异带的交会区,交会区上方及其东西两侧为具一定厚度和宽度的高阻体。在太行山山前断裂和新河断裂之间的中下地壳存在高导层,其中心对应石家庄-晋县凹陷。高导层中心部位比东西两侧浅,推测与深部热物质的上升有关。1966年邢台地震群就发生在该地区附近。

关键词: 太行山山前断裂带, 冀中坳陷, 电性结构, 壳内高导层

CLC Number:

P631.3⁺25

ZHAN Yan, ZHAO Guo-ze, WANG Li-feng, WANG Ji-jun, XIAO Qi-bin. DEEP STRUCTURE IN SHIJIAZHUANG AND THE VICINITY BY MAGNETOTELLURICS[J]. SEISMOLOGY AND GEOLOGY, 2011, 33(4): 913-927.

詹艳, 赵国泽, 王立凤, 王继军, 肖骑彬. 河北石家庄地区深部结构大地电磁探测[J]. 地震地质, 2011, 33(4): 913-927.

References

陈乐寿,王光锷.1990.大地电磁测深法［M］.北京: 地质出版社.
CHEN Le-shou,WANG Guang-e.1990.Method of Magetotelluric Sounding［M］.Geological Publishing House,Beijing(in Chinese).
邓起东,张培震,冉勇康,等.2002.中国活动构造基本特征［J］.中国科学(D辑),32(12): 1020-1030.
DENG Qi-dong,ZHANG Pei-zhen,RAN Yong-kang,et al.2002.Basic characteristics of active tectonics of China［J］.Science in China(Ser D),46(4): 356-372.
邓前辉,张木生,詹艳,等.1997.邢台震区地壳上地幔电性结构及其构造意义［J］.地震地质,19(2): 155-163.
DENG Qian-hui,ZHANG Mu-sheng,ZHAN Yan,et al.1997.Geoelectrical structure of the crust and upple mantle in the Xingtai earthquake area and its tectonic implications［J］.Seismology and Geology,19(2): 155-163(in Chinese).
邓前辉,张木生,詹艳,等.1998.邢台7.2级地震震源区的电磁阵列剖面测量与电性特征研究［J］.地球物理学报,41(2): 218-225.
DENG Qian-hui,ZHANG Mu-sheng,ZHAN Yan,et al.1998.The observation of electromagnetic array profile and electrical characteristics of the crust in Xingtai M7.2 earthquake area［J］.Chinese J Geophysics,41(2): 218-225(in Chinese).
河北地质局.1968.高邑幅1:20万地质图［Z］.北京: 地质出版社.
Hebei Geological Bureau.1968.Gaoyi Geological Map(1 :200,000)［Z］.Geological Publishing House,Beijing(in Chinese).
嘉世旭,刘昌铨.1996.邢台震源区波速比异常与地震的关系［J］.地球物理学报,39(增刊): 205-215.
JIA Shi-xu,LIU Chang-quan.1996.Vp/Vs anomaly and earthquake in Xingtai epicentral region［J］.Chinese J Geophys,39(Suppl): 205-215(in Chinese).
嘉世旭,张先康.2005.华北不同构造块体地壳结构及其对比研究［J］.地球物理学报,48(36): 611-620.
JIA Shi-xu,ZHANG Xian-kang.2005.Crustal structure and comparison of different tectonic blocks in North China［J］.Chinese J Geophys,48(36): 611-620(in Chinese).
刘国栋,史书林,王宝钧.1984.华北地区壳内高导层及其与地壳构造活动性的关系［J］.中国科学(B辑),9: 839-848.
LIU Guo-dong,SHI Shu-lin,WANG Bao-jun.1984.The crust high-conductivity layer in North China and its tectonic activity［J］.Science in China(Ser B),9: 839-848(in Chinese).
马瑾,马胜利,刘力强,等.1996.断层几何结构与物理场的演化及失稳特征［J］. 地震学报,18(2):200-207.
MA Jin, MA Sheng-li, LIU Li-qiang,et al. 1996. Geometrical textures of faults, evolution of physical field and instability characteristics［J］. Acta Seismological Sinica,9(2):261-291.
邵学钟,张家茹,章思亚,等.1993.邢台地震区深部构造背景的地震转换波探测和研究［J］.地球物理学报,36(5): 609-620.
SHAO Xue-zhong,ZHANG Jia-ru,ZHANG Si-ya,et al.1993.Study of deep structure in Xingtai earthquake area by method of converted waves of earthquakes［J］.Chinese J Geophysics,36(5): 609-620(in Chinese).
腾吉文,王国正,刘道洪,等.1975.华北平原中部地区深部构造背景及邢台地震(二)［J］.地球物理学报,18(3): 196-207.
TENG Ji-wen,WANG Guo-zheng,LIU Dao-hong,et al.1975.Crustal structure of the central part of the North China plain and the Xingtai earthquake(Ⅱ)［J］.Chinese J Geophys,18(3): 196-207(in Chinese).
肖骑彬.2004.大地电磁测深反演方法对比与可视化及应用研究［D］: 北京: 中国科学院地质与地球物理研究所.
XIAO Qi-bin.2004.Application study of magnetotelluric inversion method comparison and visualizaion［D］.Ph D thesis.Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing(in Chinese).
徐常芳.1996.中国大陆地壳上地慢电性结构及地震分布规律(一)［J］.地震学报,18(2): 254-261.
XU Chang-fang.1996.The earthquake distribution and the resistivity structure in the Chinese mainland(Ⅰ)［J］.Acta Seismologica Sinica,18(2): 254-261(in Chinese).
徐杰,方仲景,杨理华.1988.1966年邢台7.2级地震的构造背景和发震构造［J］.地震地质,10(4): 51-59.
XU Jie,FANG Zhong-jing,YANG Li-hua.1988.Tectonic background and causative fault of 1966 Xingtai M_S 7.2 earthquakes［J］.Seismology and Geology,10(4): 51-59(in Chinese).
徐杰,高占武,宋长青,等.2000.太行山前断裂带的构造特征［J］.地震地质,22(2): 111-122.
XU Jie,GAO Zhan-wu,SONG Chang-qing,et al.2000.The strucrural characters of the piedmont fault zone of Taihang Mountains［J］.Seismology and Geology,22(2): 111-122(in Chinese).
徐锡伟,于贵华,马文涛,等.2002.活断层地震地表破裂 "避让带"宽度确定依据与方法［J］.地震地质,24(4): 471-483.
XU Xi-wei,YU Gui-hua,MA Wen-tao,et al.2002.Evidence and methods for determining the safety distance from the potential earthquake surface rupture on active fault［J］.Seismology and Geology,24(4): 471-483(in Chinese).
徐锡伟,于贵华,王峰,等.2000.1966年邢台地震的发震构造模型: 新生断层形成？先存断层摩擦黏滑？［J］. 中国地震,16(4): 364-378.
XU Xi-wei,YU Gui-hua,WANG Feng,et al.2000.Seismogenic model for the 1966 Xingtai earthquakes: Nucleation of newborn fault or stick-slip of pre-existing fault?［J］. Earthquake Research in China,16(4): 364-378(in Chinese).
尹京苑,梅世蓉,薛艳.1999.邢台地震区地壳速度结构特征与强震孕育发生的关系［J］.地球物理学报,42(5): 629-639.
YIN Jing-yan,MEI Shi-rong,XUE Yan.1999.Relationship between the deep crustal features in velocity structure and the preparation of strong earthquakes in Xingtai area［J］.Chinese J Geophysics,42(5): 629-639(in Chinese).
于湘伟,张怀,陈运泰.2010.华北地区地震重新定位结果分析［J］.大地测量与地球动力学,30(2): 29-33.
YU Xiang-wei,ZHANG Huai,CHEN Yun-tai.2010.Analysis of relocated earthquakes in North China region［J］.Journal of Geodesy and Geodynamics,30(2): 29-33(in Chinese).
詹艳,赵国泽,陈小斌,等.2004.宁夏海原大震区西安州-韦州剖面大地电磁探测与研究［J］.地球物理学报,47(2): 274-281.
ZHAN Yan,ZHAO Guo-ze,CHEN Xiao-bin,et al.2004.Imaging of crustal structure from magnetotelluric profiling in the Haiyuan earthauake area,Ningxia Hui Autonomous Region,China［J］.Chinese J Geophysics,47(2): 305-313.
詹艳,赵国泽,王继军,等.2008.1927年古浪地震区及其两侧地块的深部电性结构［J］.地球物理学报,51(2): 220-229.
ZHAN Yan,ZHAO Guo-ze,WANG Ji-jun,et al.2008.Deep electric structure beneath the epicentre of the 1927 Gulang M8 earthquake and its adjacent areas from magnetotelluric sounding［J］.Chinese J Geophysics,51(2): 220-229(in Chinese).
张汝慧,赵国泽.1993.河北邢束地区地壳上地幔的热作用［J］.中国地震,9(3): 235-245.
ZHANG Ru-hui,ZHAO Guo-ze.1993.Geothermal action in crust and upper mantle beneath the Xingtai-Shulu region in Hebei Province［J］.Earthquake Research in China,9(3): 235-245(in Chinese).
赵成斌,孙振国,刘保金,等.1999.邢台地震区浅部构造特征及其与深部构造的耦合关系［J］.地震地质,21(4): 417-424.
ZHAO Cheng-bin,SUN Zhen-guo,LIU Bao-jin,et al.1999.A study of the shallow structural characteristics and the coupling relation between deep and shallow structures in Xingtai earthquake area［J］.Seismology and Geology,21(4): 417-424(in Chinese).
赵国泽,刘国栋,詹艳,等.1998.张北-尚义地震区及其邻区地壳上地幔结构［J］.地震地质,20(2): 155-162.
ZHAO Guo-ze,LIU Guo-dong,ZHAN Yan,et al.1998.The structure of the crust and upper mantle for the Zhangbei-Shangyi seismic area and its neighbouring region［J］.Seismology and Geology,20(2): 155-162(in Chinese).
赵国泽,赵永贵.1986.华北平原盆地演化中深部热、重力作用初探［J］.地质学报,1: 102-113.
ZHAO Guo-ze,ZHAO Yong-gui.1986.The formation mechanism of the North China plain basin: A comprehensive analysis of thermal and gravitational action［J］.Acta Geologica Sinica,1: 102-113(in Chinese).
Bedrosian P A,Unsworth M,Egbert G,et al.2002.Magnetotelluric imaging of the creeping segment of the San Andreas Fault near Hollister［J］.Geophys Res Lett,29(11): 1-4.
Chave A D,Thomson D J,Ander M E,1987.On the robust estimation of power spectra,coherences and transfer functions［J］.J Geophys Res,92: 633-648.
Chow Son Chen,Chien Chih Chen.2000.Magnetotelluric soundings of the source area of the 1999 Chi-Chi earthquake in Taiwan: Evidence of fluids at the hypocenter［J］.TAO,11(3): 679-688.
Egbert G,Booker J R.1986.Robust estimation of geomagnetic transfer functions［J］.Geophys J R Astr Soc,87: 173-194.
Electromagnetic Research Group for the Active Fault.1982.Low electrical resistivity along an active fault［J］.J Geomag Geoelectr,34: 103-127.
Gamble T D,Goubau W M,Clarke J.1979.Magnetotellurics with a remote magnetic reference［J］.Geophysics,44: 53-68.
Gary W McNeice and Alan G Jones.2001.Multisite,multifrequency tensor decomposition of magnetotelluric data［J］.Geophysics,66(1): 158-173.
Gurer A,Bayrak,Gurer O F.2004.Magnetotelluric images of the crust and mantle in the southwestern Taurides,Turkey［J］.Tectonophysics,391: 131-145.
Johnson P A and McEvilly T V.1995.Parkfield seismicity: Fluid-driven?［J］.J Geophys Res,100: 12937-12950.
Malcom Ingham.2005.High resolution electrical image of fault zone［J］.Physics of the Earth and Planetary Interiors,150: 93-105.
Rodi W and Mackie R L.2001.Nonlinear conjugate gradients algorithm for 2-D magnetotelluric inversion［J］.Geophysics,66(1): 174-187.
Tadanori Goto,Yasuo Wada,Naoto Oshiman,et al.2005.Resistivity structure of a seismic gap along the Atotsugawa Fault,Japan［J］.Physics of the Earth and Planetary Interiors,148: 55-72.
Tank S B,Honkura Y,Ogawa Y.2003.Resistivity structure in the western part of the fault rupture zone associated with the 1999 Izmit earthquake and its seismogenic implication［J］.Earth Planets Space,55: 437-442.
Sleep N H, Blanpied M L. 1992. Creep, compaction and the weak rheology of major faults［J］. Nature, 359: 687-692.
Unsworth M,Bedrosian P,Eisel M,et al.2000.Along strike variations in the electrical structure of the San Andreas Fault at Parkfield,California［J］.Geophys Res Lett,27(18): 3021-3024.
Unsworth M,Bedrosian P A.2004.Electrical resistivity structure at the SAFOD site from magnetotelluric exploration［J］.Geophys Res Lett,31(L12s05): 1-4.
Wang C Y,Zheng X K,Lin Z Y,et al.1997.Crustal structure beneath the Xingtai earthquake area in North China and its tectonic implications［J］.Tectonophysics,274: 307-319.
Yasuo Ogawa and Yoshimori Honkura.2004.Mid-crustal electrical conductors and their correlations to seismicity and deformation at Itoigawa-Shizuoka Tectonic Line,Central Japan［J］.Earth Planets Space,56: 1285-1291.
Zhao Guoze,Wang Lifeng,Chen Xiaobin,et al.2010.The active fault belts in eastern Tibet margin inferred using magnetotellurics［J］.Geologica Acta,8: 99-110.