青海玉树地区中强震震源参数特征研究

STUDY ON THE SOURCE PARAMETERS OF MODERATE EARTHQUAKES IN YUSHU AREA OF QINGHAI PROVINCE

利用数字化地震资料,对玉树地区2006年5.0、5.6级和2010年7.1级地震的震源机制解、尾波Q值、波速比及应力降等进行了对比研究,结果表明2010年玉树7.1级地震为走滑型与该地区历史地震的震源机制一致。2个地震序列的尾波Q值、波速比和应力降存在明显的不同,特别是玉树7.1级地震前的Ms4.7级地震出现显著差异,应力降值在地震序列的活跃、平静段表现出不同的特征。

The focal-mechanism solution, coda wave Q -value, Vp/Vs ratio and stress drop of Ms 5.6 and Ms 5.0 earthquakes in 2006 and Ms 7. 1 earthquake in 2010 in Yushu area of Qinghai province are comparatively studied by using the digital seismic data, the results show that the slide of the Ms 7. 1 earthquake is consistent with the historical earthquake focal-mechanism solution. The coda wave Q-value, Vp/Vs ratio and stress drop of the two earthquake sequences are quite different, especially the obviously precursors appeared in the Ms 4. 7 earthquake before Yushu 7. 1 earthquake, stress drop values characterized different in the active and quiet periods in the two sequences.