云南地磁台地震前地磁谐波振幅比分析

采用云南永胜和通海地磁台2010年1月至2018年12月记录的地磁分钟值数据,计算谐波振幅比随时间的变化,分析发现:2014年8月3日鲁甸6.5级地震、 2018年9月8日墨江5.9级地震前,谐波振幅比曲线有2次明显下降—转折—恢复异常,分别于第1次异常恢复上升过程和第2次异常转折过程中发震,异常持续时间分别为3年和2年多,持续时间越长,震级越高;距震中较近的地磁台站谐波振幅比曲线出现不同步现象,即Y_(ZHx)(NS)向与Y_(ZHy)(EW)向的不同步及长短周期不同步。

Analysis of geomagnetic harmonic amplitude ratio before earthquakes in Yunnan geomagnetic stations

The series of geomagnetic harmonic wave amplitude ratios are calculated in this paper, by using minute sampling data of 2 geomagnetic stations in Yunnan from January 2010 to October 2018. The asynchronous changes of the long period and the short period of geomagnetic harmonic wave amplitude ratios are considered anomalous observed before earthquakes. The geomagnetic harmonic wave amplitude ratio anomalies of Yunnan stations were found before Ludian M_S 6.5 earthquake on August 3, 2014 and Mojiang M_S 5.9 earthquake on September 8, 2018. The harmonic amplitude ratio curve had two obvious declining-turn-recovery anomalies. The curve had two obvious declining-turn-recovery anomalies. Earthquakes occurred in the process of the first abnormal recovery rising and the second abnormal turning, with the abnormal duration of 3 years and more than 2 years. The longer the duration, the higher the magnitude. The harmonic amplitude ratio curve of a geomagnetic station near the epicenter appears to be out of sync, namely the SN and EW are not synchronized, and long and short duration are not synchronized.