张北6.2级地震前电磁波频谱分析

ANALYSIS OF ELECTROMAGNETIC SPECTRUM BEFORE ZHANGBEI Ms6.2 EARTHQUAKE

基于波谱的FFT和小波变换理论,研究了张北地震前北京东三旗地磁台电磁波频谱变化特征。结果表明:1)张北地震前异常信息确实存在;2)电场较磁场异常显著,且NS分量强于EW分量;3)异常出现的时间主要集中在1997年12月31日、1998年1月1日,在时间进程上显示了明显的阶段性变化,这可能反映了地震不同孕育阶段的特征。

On the basis of the FFT spectrum and wavelet transform theory, the changing characteristics of electromagnetic wave frequence spectran of Dongsanqi station in Beijing before the Zhangbei earthquake are studied The results are as follows. 1 ） Anomalies did exist before the Zhangbei earthquake. 2） Anomalous signals of the e- lectric field are more significant than those of the magnetic field, and the NS component is stronger than the EW component. 3） Anomalies appeared concentrately on Dec. 31,1997 and Jan. 1 , 1998 and there were significant phase changes that it might reflect the different stage characteristics of earthquake preparation.