利用谱振幅相关系数法对发生在我国东北地区的2 次中强地震进行研究。结果显示，1999 年辽宁岫岩5. 4 级地震前震序列谱振幅相关系数平均值为0. 90，2013 年吉林前郭5. 8级震群谱振幅相关系数平均值为0. 88，表明二者均表现出较强的震源机制相似性，具有发生强震的背景条件，与已有研究结果一致。此外，岫岩5. 4 级地震余震序列的谱振幅相关系数有所下降。值得注意的是，前郭震群序列前期相关系数维持在高值，5 次强震发生后其值有下降的趋势，表现出震源机制相似性的减弱，这对中强震群后续趋势的判定具有一定的启发意义。

The paper applies the method of correlation coefficient of spectral amplitude to two mid-strong earthquakes in northeast China． The results show the mean correlation coefficient of spectral amplitude of the Xiuyan MS5． 4 foreshock sequence in 1999 is 0． 90，and the Qianguo MS5. 8 earthquake swarm is 0． 88． It suggests that both earthquake sequences have the feature in focal mechanism similarity，and have the background condition of strong earthquake． This result conforms to the former research． In addition，the correlation coefficient of spectral amplitude of Xiuyan MS5. 4 aftershock sequence has a trend of reduction． It is worth noting that the correlation coefficient of spectral amplitude is larger before the five strong earthquakes in the Qianguo earthquake swarm． But it becomes smaller afterward，which means focal mechanism similarity has been less． The findings give us a meaningful enlightenment in determining the trend of the medstrong earthquake swarm．

中国地震局地震预测研究所基本科研业务专项(2012IES0201)、中国地震局监测预报司震情跟踪青年课题(2015010126)共同资助