1985: TANGSHAN 1976 EARTHQUAKE AND THE OPTIMUM OBSERVATION STRATEGY FOR SEISMOMAGNETISM. Acta Seismologica Sinica, 7(3): 300-313.
Citation: 1985: TANGSHAN 1976 EARTHQUAKE AND THE OPTIMUM OBSERVATION STRATEGY FOR SEISMOMAGNETISM. Acta Seismologica Sinica, 7(3): 300-313.

TANGSHAN 1976 EARTHQUAKE AND THE OPTIMUM OBSERVATION STRATEGY FOR SEISMOMAGNETISM

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  • Published Date: August 31, 2011
  • Based on the theory of three-dimensional seismomagnetic modelling proposed by the author,Hastie and Staeey,a computation for the Tangshan 1976 earthquake is undertaken. The piezomagnetic anomalies of seven models with different orientations,dip angles and depths of the fault at different magnetic latitudes are compared. The results indicate that seismomagnetic effect is strongly dependent on the focal mechanism of the earthquake. It appears that strike-slip fault with a dip angle of 45-60 provides the optimum observation condition where the maximum piezomagnetic anomaly is as high as 12 nT. The worst condition for seismomagnetic observation appears when the fault is located at the magnetic equator,or orients magnetic E-W,or with a focal depth of 10 km o>r more. Under one of such circumstances the corresponding piezomagnetic anomaly can hardly be detected. In most of the models,anomaly of the vertical component is slightly higher than that of the total field strength and reaches an extreme value of three fold of the latter when the fault is located at the magnetic equator. Computation for the Tangshan earthquake shows that the maximum anomaly is about 3-4 nT and the ratio of the linear extension of the area with an anomaly exceeding InT to the fault length is only 1.04-1.10. Since the piezomagnetic field is a weakly induced field by an earthquake,the fact that no obvious magnetic precursor to this earthquake had been measured seems to 'be due to the low sensitivity of the magnetometers involved and their large epicentral distances.
  • [1] 郝锦绮,L. M. Hastie和F. D. Stacey,三维位错模式的地震压磁效应,地震学报,6,558——5i3,1984,

    [2] Mansinha, L. and D. E. Smylie, The displacement fields of inclined faults, Bull. Seismol. Soc. Am.,61, 1433——1440, 1971.

    [3] 陈运泰,黄立人、林邦慧、刘妙龙和王新华,用大地测量资料反演的1976年唐山地震的位错模式,地球物理学报,22, 201——217, 1979,

    [4] Butler, R., G. S. Stewart and H. Kanamori, The July 27, 1976 Tangshan, China Earthquake——a complex sequence of intraplate events, Bull. Seism. Soc. Am., 69, 207——220, 1979.

    [5] 张之立,唐山地震的破裂过程及其力学分析,地震学报,2, 111——129, 1980,

    [6] Gao, L., M. Xu and P. Huang, Variations of the susceptibility of rock samples before and after fracture under uniaxial compression,J.Geornag. Geoelectr., 34, 265——281, 1982.

    [7] 国家地震局《一九七六年唐山地震》编辑组,一九七六年唐山地震,地震出版社,228——245, 1982,

    [8] 林云芳、曾小苹、郭启华,中国华北地区地磁长期变化的分析,地震学报,4, 7 4——83,1982,

    [9] 孙若昧、卢振业,唐山地震前磁场长期变的局部异常,地震研究,5, 391——408, 1982,

    [10] 范国华、侯作中、詹志佳、黄平章,唐山地震对北京地区地磁场总强度的影响,地震学报,1,39——89, 1979,

    [11] 任熙宪、祁贵仲、詹志佳,唐山地震前后北京地区地磁场总强度的变化,地震学报,271——286,1988

    [12] 曾融生、张少泉、周海南、何正勤,唐山地震区的地壳结构及大陆地震成因的探讨,地震学报,7, 2, 126——142,1985,

    [13] 孙武城、刘昌锉,从地震测深看华北盆地地壳深部构造的若干特征,朱夏主编,中国中新生代盆地构造和演化,科学出版社,1984,

    [14] 邵学钟等,利用地震转换波探测地壳、上地馒构造试验,地球物理学报,21, 89——100.1978,

    [15] 郝书俭、高华根、王春华,京津唐地区居里等温面及其与地震的关系,地球物理学报,25, 264——269, 1982

    [1] 郝锦绮,L. M. Hastie和F. D. Stacey,三维位错模式的地震压磁效应,地震学报,6,558——5i3,1984,

    [2] Mansinha, L. and D. E. Smylie, The displacement fields of inclined faults, Bull. Seismol. Soc. Am.,61, 1433——1440, 1971.

    [3] 陈运泰,黄立人、林邦慧、刘妙龙和王新华,用大地测量资料反演的1976年唐山地震的位错模式,地球物理学报,22, 201——217, 1979,

    [4] Butler, R., G. S. Stewart and H. Kanamori, The July 27, 1976 Tangshan, China Earthquake——a complex sequence of intraplate events, Bull. Seism. Soc. Am., 69, 207——220, 1979.

    [5] 张之立,唐山地震的破裂过程及其力学分析,地震学报,2, 111——129, 1980,

    [6] Gao, L., M. Xu and P. Huang, Variations of the susceptibility of rock samples before and after fracture under uniaxial compression,J.Geornag. Geoelectr., 34, 265——281, 1982.

    [7] 国家地震局《一九七六年唐山地震》编辑组,一九七六年唐山地震,地震出版社,228——245, 1982,

    [8] 林云芳、曾小苹、郭启华,中国华北地区地磁长期变化的分析,地震学报,4, 7 4——83,1982,

    [9] 孙若昧、卢振业,唐山地震前磁场长期变的局部异常,地震研究,5, 391——408, 1982,

    [10] 范国华、侯作中、詹志佳、黄平章,唐山地震对北京地区地磁场总强度的影响,地震学报,1,39——89, 1979,

    [11] 任熙宪、祁贵仲、詹志佳,唐山地震前后北京地区地磁场总强度的变化,地震学报,271——286,1988

    [12] 曾融生、张少泉、周海南、何正勤,唐山地震区的地壳结构及大陆地震成因的探讨,地震学报,7, 2, 126——142,1985,

    [13] 孙武城、刘昌锉,从地震测深看华北盆地地壳深部构造的若干特征,朱夏主编,中国中新生代盆地构造和演化,科学出版社,1984,

    [14] 邵学钟等,利用地震转换波探测地壳、上地馒构造试验,地球物理学报,21, 89——100.1978,

    [15] 郝书俭、高华根、王春华,京津唐地区居里等温面及其与地震的关系,地球物理学报,25, 264——269, 1982
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