| 华北和东北地区地磁场变化与大地震的关系 |
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| 引用本文： | 林云芳,曾小萍,董玉兰,郭启华,侯东翔,郭树林,钟国英,于明鑫.华北和东北地区地磁场变化与大地震的关系[J].地震学报,1988,10(4):396-405. |
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| 作者姓名： | 林云芳 曾小萍 董玉兰 郭启华 侯东翔 郭树林 钟国英 于明鑫 |
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| 作者单位： | 1. 国家地震局地球物理研究所
2. 辽宁省地震局
3. 吉林省地震办公室长春地磁台
4. 辽宁省地震局大连地磁台 |
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| 摘 要： | 本文采用按距离加权最小二乘曲面拟合方法计算分析了东亚及其邻区50个地磁台站地磁偏角D,水平强度H,垂直分量Z和总强度F 1970——1979年的逐年变化和结果表明,大约在纬度=37——40N,经度=123——126E附近,（1——13）104平方公里的空间范围內,地磁场三要素及总强度的逐年变化存在明显的负异常。 这些负异常的出现和消失与1975年在海城发生的震级M=7.3级地震和1976年在唐山发生的M=7.8级地震有较好的对应关系。地磁负异常中心处对应上述两次大震前的最大值分别为=1.5和2.0/a并指向震中方向,10和25nT/a,10和30FnT/a,10和45nT/a。这种磁异常可能是太平洋板块向中国大陆板块俯冲运动和上地幔中某种物质流动的结果。
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| 关 键 词： | 地磁异常 震磁效应 曲面拟合 |
GEOMAGNETIC ANOMALOUS CHANGES AND EARTHQUAKES IN NORTH AND NORTHEASTERN CHINA |
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| Institution: | 1. Institute of Geophysics, State Seismological Bureau;
2. Seismological Bureau of Liaoning Province;
3. Changchun Geomagnetic Observatory, Seismological Office of Jinlin Province;
4. Dalian Geomagnetic Observatory, Seismological Bureau of Liaoning Province. |
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| Abstract: | In this paper the method of distance-dependent weights and least squares surface fitting has been applied to the calculation and analysis of the changes from the year 1970.0 through year 1979.0 of the geomagnetic declination D, horizontal intensity H, vertical component Z and total intensity F at 50 geomagnetic observatories in East Asia and its vicinity.The results show that there exist geomagnetic anomalies in the four magnetic quantities mentioned above in the years from 1971 through 1976 in a region about 13104km2 covering latitudes(37-40) N, longitudes (123-126) E. A good correspondence has been found between the appearance of the negative anomalies and the two earthquakes in Northeastern China which occurred in 1975 at Haicheng with M = 7.3 and in 1976 at Tangshan with M = 7.8. This anomaly did not last long after the latter earthquake. The maximum negative geomagnetic anomalies of declination and intensities at the central part of the anomalous region before the Haicheng and the Tangshan earthquakes were respectively D=1.5' and 2.0' per year all pointed toward the epicenters; H=10 and 25nT per year; Z =10 and 30nT per year; F = 10 and 45nT per year. It seems that geomagnetic anomalies were caused by the su-bduction of the Pacific Plate beneath the China Plate along the Japan Trench and by the flow of mass in the upper mantle. |
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