2009年“霍山窗”小震群S波分裂研究

Shear wave splitting of a small earthquake swarm in the “Huoshan seismic window”

摘要:

采用互相关系数法，计算了2009 年“霍山窗”地区小震群S 波分裂参数，结果表明，S波分裂现象明显，快S 波平均偏振方向为NEE，与区域最大水平主压应力方向基本一致。通过分析延迟时间随时间的变化趋势，发现延迟时间在几次较大地震前呈现增加的趋势，并且在临震前短时间内出现减小的现象。这一现象符合震前应力长时间积累和短时间应力释放的地震孕育发生机制，而时间延迟在强震前出现下降则可能具有重要的地震短临预测意义。

Abstract:

Using the correlation coefficient method，it studies shear wave splitting on the basis of the records of a small earthquake swarm in the“Huoshan seismic window”． The results show that the preponderant polarization of fast shear wave is NEE． It accords with the regional predominant direction of principal compressional stress． The time delay would basically increase before strong shocks． However，it was observed that the time delay abruptly decreased immediately before one strong shock． It is consistent with the conclusion that long-term stress accumulation and short-term stress relaxation exist before earthquakes． It is significant for the short-term earthquake prediction that the time delay will decrease before strong earthquakes． The result suggests the parameters of shear wave splitting may reflect the dynamic change of region stress field and provide useful information for the study of stress field and earthquake prediction．