2013年8月德钦—得荣MS5.9地震序列S波分裂

摘要

In this paper, combing aspect ratio method and the polarization analysis method, the polarization direction of fast shear wave and the delay time of slow shear waveform in the seismic data from August 2013 to February 2015 are measured. Finally, we got 272 pairs shear waves splitting parameters at BZL station. The equal area rose diagram shows the dominant polarization directions of fast shear waves are NWW,consistent with the strike of fault and the major axis of distribution of earthquakes. The shear waves splitting become disorder after the MS 5.9 earthquake occurred. The delay times of slow shear waves decrease quickly in 1 day after the MS 5.9 earthquake occurred, indicating the crustal stress released suddenly before the big earthquakes.%2013年8月28日、31日云南德钦、四川得荣交界地区分别发生MS 5.2、MS 5.9地震,采用纵横比与偏振分析相结合的方法,测定此次地震序列S波分裂参数,即快波偏振方向和慢波延迟时间.BZL流动地震台得到272对S波分裂参数,等面积玫瑰图显示快波优势方向为NWW向,与台站附近断层走向和地震序列分布长轴方向一致;在MS 5.9地震发生后,快波偏振方向出现紊乱现象;观测到在MS 5.9地震发生的前一天慢波延迟时间迅速下降,表明较大地震发生前地壳应力突然释放.