中文摘要：

为了提取2013年10月至11月吉林省松原市Ms5.0以上震群前后地磁异常变化信息,利用短时快速傅里叶变换方法,分析平均震中距为79 km的长春地磁台地磁场能量波动,发现该台Z分量在震前4个月于0.02 Hz频点能量出现异常波动,震前2个月达到峰值,随后逐渐平稳,恢复到正常水平期间发生地震.排除空间变化磁场影响和环境干扰,认为该异常变化与2013年松原Ms5.0以上震群有关.

英文摘要：

In order to find geomagnetic abnormality associated with Songyuan earthquakes, the vari- ance of geomagnetic energy of Changchun station, which is 79 km away from the epicenter, was calculated based on SFFT-transform. The result showed that there was an obvious en- hancement around 50s of Z component about 4 months before earthquake and which reached to the maximum about 2 month before. The earthquake happened when it back to normal. We think the unusual enhancement of Z component related to Songyuan earthquake swarms.