野外地震地磁测量的主磁场长期变化改正方法研究

Correction method for secular variation in the main geomagnetic field using a field seismogeomagnetic survey

本文应用野外测点的重复测量数据,通过加权最小二乘方法,对测量数据进行了长期变改正,并与现行方法的结果进行了对比。统计数据表明:①新方法显著改善了原方法存在的长期变空间畸变问题,产出的主磁场长期变化结果与IGRF_SV模型的线性相关程度更高。“F、D、I”3要素与IGRF_SV模型“差值的均方差”,分别为原方法结果的“10.7%、47.0%、14.5%”;②应用新的长期变化改正方法,可获得更加稳定、合理的地壳磁场变化结果。“F、D、I”3要素地壳磁场变化的“平均幅度”分别为原结果的“28.5%、55.4%、34.4”,“均方差”分别为原结果的“59.1%、56.5%、40.3%”,“平均梯度”分别为原结果的“93.6%、91.9%、97.0%”;③在新方法的处理结果中,震磁信息得到明显的优化,震中位置与地壳磁场变化“0”值线的吻合程度明显更好。新方法的处理结果明显优于原方法,具备较高的应用价值。

Using the repeated survey data from field stations and the weighted least-squares method,this study obtained the long-term correction results of the measurement data and compared these results with those of current methods.The results were as follows:1.The new method substantially improved long-term spatial distortion compared to the old method.The secular variation(SV)results of the main geomagnetic field produced by the new method have a higher linear correlation to those of the international geomagnetic reference field(IGRF)_SV model.The mean square error(MSE)of the difference in the three elements F,D,and I between the new method and the IGRF_SV model is 10.7%,47.0%,and 14.5% of that of the original method,respectively.2.Applying the new SV correction method obtains more stable and reasonable variations in Earth’s crustal magnetic field.The average amplitude of the Earth’s crustal magnetic field variation in F,D,and I is 28.5%,55.4%,and 34.4 of the original results,the MSE is 59.1%,56.5%,and 40.3% of the original results,and the mean gradient is 93.6%,91.9%,and 97.0%,respectively.3.In the processed results of the new method,the seismomagnetic information is clearly optimized,and the epicenter location is more consistent with the 0 value line of the Earth’s crustal magnetic field.The processed results of the new method are considerably better than those of the original method and have a higher application value.