中国大陆西部强震前超低频磁场时空变化特征

Spatio-temporal variation characteristic of the ultra-low frequency magnetic field prior to strong earthquakes of western Chinese mainland

  • 摘要: 对2015年至2019年期间中国大陆西部的磁通门磁力仪秒采样观测资料开展了5—100 s频段的地磁垂直强度极化分析,并运用一些数学方法对分析结果进行了处理。结果显示,极化高值在经向和纬向均无明显的形态和幅值变化,且极化高值与地磁外源场扰动无关。在此基础上筛选出18次极化高值异常事件,利用插值方法得到了极化高值异常的空间分布图,并分析了18次高值异常与中国大陆西部及周边15次强震的时空关系。分析结果表明:地磁场出现多台同步极化高值现象后的半年内,高值区可能发生M6.0以上强震;高值现象出现后,多个高值区均有可能发生强震;后续强震的震级与高值区面积呈正相关。

     

    Abstract: Based on the one second sampling data from fluxgate magnetometers in western Chinese mainland from 2015 to 2019, this paper carried out the vertical component polarization analysis of the frequency band between 5 s to 100 s, and then processed the analysis results by some mathematical methods. The results show that the high polarization value has no obvious shape and amplitude change in both meridional and zonal directions, and the high polarization value has nothing to do with geomagnetic field disturbance. On this basis, 18 high-value anomalies were screened out, and their spatial distribution map was obtained by interpolation method. The results show that within half a year after the synchronous appearance of multiple high-value anomalies of the vertical component polarization of geomagnetic field, the high-value region may have a strong earthquake with magnitude over M6.0. After the appearance of high value phenomenon, several high value regions are likely to have strong earthquakes; furthermore the magnitude of subsequent strong earthquake seems to be positively correlated with the area of the high-value zone.

     

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