强震前重力场等位面二次偏微商异常变化分析
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摘要
采用相关分析方法对北京平谷台 1971～ 1977年获得的重力位 2次偏微商曲率值 K进行处理 ,消除降雨等噪声对观测值的影响 ,得到较真实的重力等位面弯曲变化值 KS。分析研究的结果表明 ,1975年 2月 4日海城 7.3级地震、1976年 7月 2 8日唐山 7.8级地震、1976年 11月 15日宁河 6 .9级地震、1977年 5月 12日宁河 6 .5级地震前 ,曲率值 KS均有明显的震前异常出现。在此基础上进行定量分析处理 ,求得各次地震前 KS值的真正异常变化量△ KS,并运用近似积分法求得异常面积与地震震级之间的关系 ,初步建立了预报方程 ,从而为单台重力异常预报不同距离发生的地震震级提供一种借鉴方法
A correlation analysis method was used to process the quadratic partial derivative curvature vector of gravity potential (\%K\%) obtained at Pinggu station from 1970 to 1977, so as to remove the influence of the noises from rainfall and the like, and get vector \%K\-s\% which represents the true value of the bending degree of equi potential surface of gravity. Analysis of \%K\-s\% shows that obvious anomalies appeared prior to the Haicheng earthquake of \%M\%s7.3 on Feb. 4, 1975, the Tangshan earthquake of \%M\%s7.8 on Jul. 28, 1976, the Ninghe earthquake of \%M\%s6.9 on Nov. 15, and the Ninghe earthquake of \%M\%s6.5 on May 12, 1977. We use a parameter \%△K\-s\% to quantitatively describe the anomalous change of \%K\-s\% prior to earthquakes, and then a prediction equation was established by studying the statistic relationship between the time integration of \%△K\-s\% and the magnitude of earthquakes, and this way supply a reference prediction method for the estimation of the magnitude of coming earthquakes with different epicentral distance by using gravity data from a single station.
A correlation analysis method was used to process the quadratic partial derivative curvature vector of gravity potential (\%K\%) obtained at Pinggu station from 1970 to 1977, so as to remove the influence of the noises from rainfall and the like, and get vector \%K\-s\% which represents the true value of the bending degree of equi potential surface of gravity. Analysis of \%K\-s\% shows that obvious anomalies appeared prior to the Haicheng earthquake of \%M\%s7.3 on Feb. 4, 1975, the Tangshan earthquake of \%M\%s7.8 on Jul. 28, 1976, the Ninghe earthquake of \%M\%s6.9 on Nov. 15, and the Ninghe earthquake of \%M\%s6.5 on May 12, 1977. We use a parameter \%△K\-s\% to quantitatively describe the anomalous change of \%K\-s\% prior to earthquakes, and then a prediction equation was established by studying the statistic relationship between the time integration of \%△K\-s\% and the magnitude of earthquakes, and this way supply a reference prediction method for the estimation of the magnitude of coming earthquakes with different epicentral distance by using gravity data from a single station.
引文
1 FengDeyi.Observational results and theory on the de-velopment process of three stages of earthquake precur-sor[J].EarthquakeResearch,1983,6(2):90-99.(inChinese)
2 SongZhiping,et al.Stage- by- stage characteristics ofearthquake swarm activity in theNorthChina[J].Earthquake,2001,21(1):47-52.(inChinese)
3 WuBing andXuHouze.Characteristics of gravitationalprecursor prior toTangshan earthquake[A ].See:Re-view and research on theTangshan earthquake[C].Bei-jing:SeismologicalPress,1981,198-206.(inChinese)
4 WangGuixuan,YuShuping andL iaoGuancheng.Thesecondary derivative change of gravitational potentialbeforeTangshan earthquake[J].Earthquake,1995,15(1):37-43.(inChinese)
5 FangJun.Gravity survey and figure of theEarth[M].Beijing:SciencePress,1965,219-222.
2 SongZhiping,et al.Stage- by- stage characteristics ofearthquake swarm activity in theNorthChina[J].Earthquake,2001,21(1):47-52.(inChinese)
3 WuBing andXuHouze.Characteristics of gravitationalprecursor prior toTangshan earthquake[A ].See:Re-view and research on theTangshan earthquake[C].Bei-jing:SeismologicalPress,1981,198-206.(inChinese)
4 WangGuixuan,YuShuping andL iaoGuancheng.Thesecondary derivative change of gravitational potentialbeforeTangshan earthquake[J].Earthquake,1995,15(1):37-43.(inChinese)
5 FangJun.Gravity survey and figure of theEarth[M].Beijing:SciencePress,1965,219-222.
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