【摘要】 利用2004年8月16日—2008年5月11日双差精定位后的地震S波资料,采用衰减层析成像方法对紫坪铺水库区域地壳QS进行动态衰减成像,反演得到了该区的QS动态演化特征.以1个月为步长、1年为窗长,计算了紫坪铺水库地区不同大小区域按月滑动的平均QS值,统计了不同震级范围按月滑动的地震频次,并分别与水位进行了对比分析.研究结果表明,水位首次快速加载后,紫坪铺水库低QS值区域范围扩大,QS值下降,水库西南区、东北区、库区中段、东北岸QS值的变化较为明显.紫坪铺水库不同大小区域按月滑动的平均QS值随蓄水时间的增加、水位的升高而减小,库区中段QS值下降最为剧烈.水库蓄水增强了该区的地震活动性,对ML0.0—2.0的小震活动影响较为显著.更多还原

【Abstract】 Using a two-dimensional seismic attenuation tomography technique,the crustal QS dynamic variation in Zipingpu reservoir area,Sichuan Province,was obtained by inverting S-wave data from relocated earthquakes from 16 Aug.2004 to 11 May 2008 with the double-difference algorithm.Monthly moving average QS value in different-sized regions and earthquake frequency for different magnitude range were compared with the water level of the Zipingpu reservoir,respectively(the window length is 1 year and the step length is 1 month).The result shows that low-QS region expanded and QS value dropped significantly around the reservoir area during the first fast water-loading period.In particular,QS value varied remarkably in the southwestern,northeastern and middle parts of the reservoir area.Monthly moving average QS values for different-sized regions in the Zipingpu reservoir area decrease with elapsed impoundment time and increased water level,and the QS value in the middle reservoir area dropped sharply.Furthermore,the impoundment enhanced seismic activity in the reservoir area,and mainly increased activity of small earthquakes of ML0.0—2.0.更多还原