| 中国华北地区地磁长期变化的分析 |
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| 引用本文： | 林云芳,曾小苹,郭启华.中国华北地区地磁长期变化的分析[J].地震学报,1982,4(1):74-83. |
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| 作者姓名： | 林云芳 曾小苹 郭启华 |
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| 作者单位： | 国家地震局地球物理研究所 |
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| 摘 要： | 本文分析处理了华北及其邻近地区以及日本三个地磁台1960——1977年的水平分量(H)、垂直分量(Z)和总强度(F)的观测资料。结果表明,华北地区Z的逐年变化在1974————1976年呈现一个由下降到上升的转折,但华北南部和北部的转折时间和速率存在着局部性差异,同时,等变线在空间上亦有由南向北的移动现象。H和F同样具有类似的区域性特征。 华北地区的上述差异,曾被一些作者认为是唐山地震的磁效应。他们提出:北京、昌黎地区地震前出现约数伽马至十几伽马的负异常。从本文的分析可以看出,这种负异常并非局部性的,它只不过是长期变化大尺度区域性特征的一种表现而已。
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AN ANALYSIS OF THE GEOMAGNETIC SECULAR VARIATION OF NORTH CHINA |
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| Institution: | Institute of Geophysics, State Seismological Bureau |
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| Abstract: | In this paper, the geomagnetic observational data of the horizontal intensity (H), the vertical intensity (Z) and the total intensity(F) for the period 1960-1977 at several observatories in North China and its vicinity and also at three observatories in Japan are analysed. The results show that from 1974 to 1976 in North China, the yearly variation of the vertical intensity consists of a stage from decreasing to increasing in values. But there is a local difference in the time length of the stage and rate of change between the northern and southern parts of North China. Also, there appears a displacement of the isomagnetic lines of the rate of annual variation from the south to the north. For H and F of this area, similar regional difference can be seen.The above differences has been interpreted by some authors as the geomagnetic effect of the Tangshan Earthquake. They maintain that there occurred in Beijing and Changli prior to the earthquake a negative anomaly of a few to more than 10 gammas. But according to our analysis, the negative magnetic anomaly is not a local phenomenon but a large scale regional exihibition of a secular magnetic variation. |
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