地震前后岩石圈磁场变化特征分析
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摘要
本文以九江瑞昌M_s 5.7级地震和汶川M_s 8.0级地震为研究对象,根据两个震区地震后观测所得地磁场三分量数据和"2005.0中国地磁图"项目所积累的地磁场三分量数据,建立了两个震区的岩石圈磁场模型.通过对比分析两个震区岩石圈磁场总强度、磁偏角、磁倾角三个独立分量地震前后的时空变化特征,初步探讨地震与岩石圈磁场变化关系,寻找有效震磁变化信息.结果表明:(1)两次震中均位于岩石圈磁场的磁偏角和磁倾角零值线附近;(2)震后震中百公里范围内岩石圈磁场分量均出现了不同程度的异常变化;(3)震中附近岩石圈磁场出现了明显的与地震相关的变化,该变化在两个震区表现出相近的规律性.
This paper focuses on the geomagnetic field variation produced by lithosphere before and after the M_s = 5.7 Jiujiang-Ruichang earthquake and the M_s = 8.0 Wenchuan earthquake.According to the three-component survey data after these earthquakes and "2005.0 China Geomagnetic Chart" before the earthquakes,lithospheric geomagnetic field models of the two research regions are established.The relations between the earthquakes and different components of the geomagnetic field are preliminarily researched,by comparing and analyzing the variation characteristics of the geomagnetic field (F,D,I,) in the Jiujiang-Ruichang and Wenchuan region.The results show that two earthquake epicenters are located in the vicinity of declination and inclination zero line.After the earthquakes,different components of the geomagnetic field produce different abnormal changes.There are some obvious changes of the geomagnetic field related with the earthquakes in the vicinity of epicenters,and the changes of two earthquake regions have similar regularity.
This paper focuses on the geomagnetic field variation produced by lithosphere before and after the M_s = 5.7 Jiujiang-Ruichang earthquake and the M_s = 8.0 Wenchuan earthquake.According to the three-component survey data after these earthquakes and "2005.0 China Geomagnetic Chart" before the earthquakes,lithospheric geomagnetic field models of the two research regions are established.The relations between the earthquakes and different components of the geomagnetic field are preliminarily researched,by comparing and analyzing the variation characteristics of the geomagnetic field (F,D,I,) in the Jiujiang-Ruichang and Wenchuan region.The results show that two earthquake epicenters are located in the vicinity of declination and inclination zero line.After the earthquakes,different components of the geomagnetic field produce different abnormal changes.There are some obvious changes of the geomagnetic field related with the earthquakes in the vicinity of epicenters,and the changes of two earthquake regions have similar regularity.
引文
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[2] Chapman S,Bartels J.Geomagnetisml [J].Clarendon Press,Oxford.1940
[3] Langel R A.The main geomagnetic field[J].In:Geomagnetism,Vol.1,ed.Jacobs J A.USA:Academic Arkani Hamed.1987,249～ 512．
[4] 顾左文,张毅,姚同起,等.九江瑞昌Ms5． 7地震地磁异常地观测与分析[J].地震学报,2006,28(6) :611～621． Gu Z W,Zhang Y,Yao T Q,etal.Observation and analysis of geomagnetic abnormity associated with the M_s = 5． 7 Jiujiang-Ruichang earthquake[J].ACTA Seimologica Sinica ,2006,28(6) :611～621．
[5] 高金田,安振昌,顾左文,等.地磁正常场的选取与地磁异常场的计算[J].地球物理学报,2005,48(1) :56～62． Gao J T,An Z C,Gu Z W,et al.Selections of the geomagnetic normal field and calculations of the geomagnetic anomalous field[J].Chinese Journal of geophysics,2005,48 (1) :56～62．
[6] 安振昌.计算震磁背景场的数学方法[J].地震地磁观测与研究,2000,21(5) :9～15． An Z C.Mathematical methods to calculate the seismogeomagnetic background field [J].Seismological observation and research,2000,21(5) :9～15．
[7] 丁鉴海.地磁预报地震方法探索[A].地震监测与预报方法清理成果汇编-地磁地电分册[M].1988,108～122． Ding J H.Explore earthquake forecast method by geomagnetism[A].Compilation of earthquake monitoring and forecast method sorting out result-geomagnetism and seismic electrical fascicule[M].1988,108～122．
[8] 王墩,肖和平,姚运生,等.九江瑞昌地震序列的构造背景与发震构造探讨[J].大地测量与地球动力学,2007,27(7) :15～20． Wang D,Xiao H P,Yao Y S,et al.On seismogenic and its background tectonics of Jiujiang-Ruichang seismic sequence[J].Journal of geodesy and geodynamics,2007,27(7) :15～20．
[9] Burchfiel B C,Royden L H,Vander Hilst R D,等.中国四川2008年5月12日汶川地震的地质与地球物理背景[J].国际地震动态,2008,8(8) :13～21． Burchfiel B C,Royden L H,Vander Hilst R D,et al.A geological and geophysical context for the Wenchuan earthquake of 12 May 2008,Si-chuan,People's Republic of China,Recent Developments in World Seismology,2008,8 (8) :13～21．
[10] 徐胜峰,李勇根,曹宏.地震岩石物理研究概述[J].地球物理学进展,2009,24(2) :680～691． Xu S F,Li Y G,Cao H.A review of seismic rock physics ,Progress in Geophys [J].(in Chinese) ,2009,24(2) :680～ 691．
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