Abstract:

The EM measurement of earthquake monitoring for M_S 6.4 Ning'er aftershock series has been done at a continuous observation site after the earthquake on June 3,2007.The data was observed for 14 days.Very strong coseismic signals of aftershocks were found in the magnetic and electric fields' time series data.Electric and magnetic auto power spectrums have been obtained by using FFT in the bihourly data.The spectrum variations for the same frequency were compared.It was found that the peak of all components bounced before and after earthquakes of M_S≥3.0.This phenomenon may be corresponding to the coseismic signal and the electromagnetic precursor before and after the earthquake.We also discussed the mechanism in the paper and the seismo-dynamo effect seems to be a plausible mechanism.

Key words: Ning’er earthquake, aftershock, coseismic signal, electromagnetic field

摘要：

2007年6月3日宁洱县境内发生6.4级地震,在地震区跨越宁洱东支断裂进行了为期14d的余震序列宽频带电磁异常连续观测。在固定台站的电场和磁场时间序列记录中,观测到多次余震事件的电磁同震现象。取每2h观测资料进行了加窗傅氏变换,得到不同频率的功率谱随时间的变化曲线。结果表明,M_S3.0以上的余震发生前后,电磁场各分量频率谱峰值出现了显著的变化,地震后的峰值波动也许与时间域的同震效应相对应,而地震前发生的峰值跳跃有可能为电磁前兆现象。此外,本文对同震电磁信号产生机理进行了讨论,推测这种现象可能与地震发电机机制有关。

关键词: 宁洱地震, 余震, 同震信号, 电磁场