高邮­宝应4.9级地震地磁谐波振幅比异常特征初步分析

The preliminary analysis on the characteristics of geomagnetic harmonic wave amplitude ratios before the Gaoyou­Baoying MS4.9 earthquake

摘要:

针对高邮-宝应4.9级地震发生前后附近地区未发生其它中等以上地震、地震事件孤立及周边地磁台站分布较密有利于研究地震地磁异常时空特征的特点，较为系统地分析总结了该地震发生前后地磁谐波振幅比的变化特征。研究结果进一步验证了目前对地磁谐波振幅比异常特征的认识，即地磁谐波振幅比异常特征表现出与地电阻率类似的下降-转折-恢复上升的异常变化过程，地震一般发生在异常转折或恢复上升过程中，距震中较近的台站会出现不同步现象，即SN向与EW向的不同步以及长短周期的不同步。

Abstract:

In this paper，the Gaoyou-Baoying MS4.9 earthquake was analyzed by the geomagnetic harmonic wave amplitude ratios method. As the earthquake was an isolated seismic event，before and after which there were no other earthquake occurring in this region，and the distribution of geomagnetic observation stations was dense，there is an advantageous condition for the characteristics analysis of the geomagnetic harmonic amplitude ratio. The analysis results verify the former knowledge about anomaly characteristics of the geomagnetic harmonic amplitude ratio，that is，the anomalous characteristics of the earthquake mostly appeared in the twist-recovery process. The results also show that the observation stations close to the epicenter didn't show the same phenomena. The anomalous characteristics were different between the northern stations to the southern stations. The difference also existed between the long and short periods.