瀑布沟库区地震活动及应力场特征  

Characteristic of seismicity and stress field of the Pubugou reservoir

作　　者：阮祥[1] 张永久[1] 谢蓉华[1] 胡先明[1] 杜瑶[1] 

机构地区：[1]四川省地震局,成都市人民南路三段29号610041

出　　处：《中国地震》2013年第3期316-326,共11页Earthquake Research in China

基　　金：中国地震局地震科技星火计划项目(XH-1022);国家科技支撑项目"汶川地震断裂带科学钻探--断裂带深部流体观测及其与余震活动关系研究(WFSD-10-03)"共同资助

摘　　要：通过对瀑布沟水库和成都数字遥测地震台网记录的波形数据的研究发现,四川瀑布沟水库库区大量的所谓小震活动皆是爆破成因,从而改变了此前对该库区蓄水前地震活动密集,蓄水后地震活动骤然平静的认识。2009年11月水库蓄水后在蓄水区域周边10km范围内仅发生M L1.5以上地震1次,即2010年8月8日M L1.7地震,蓄水前后小震稀少。水库西侧的2个地震密集区的走滑型地震占较大比例,区域主压应力为NWW向。水库东、北部区域的地震震源机制解呈多种类型。瀑布沟水库区小震活动总体受区域应力场控制,NWW向近水平主压应力有利于库区NNW向中小断裂发生走滑型错动。By using waveform data from the Pubugou reservoir seismographic network and Chengdu digital telemeter seismographic network,we found lots of small earthquakes in reservoir area are results of explosions.The research has changed the previous understanding that seismicity level is higher before the impoundments rather than after.There was one earthquake with magnitude greater than ML1.5 within 10km of water area of the Pubugou area after impoundment：ML1.7 on August 8,2010.In fact,earthquake occurring before or after impoundment is rare.The proportion of strike-slip earthquakes is larger than others in the two clusters which are on the west of Pubugou reservoir,and the direction of principal compressive stress of these clusters is NWW.On the east and north of reservoir the focal mechanisms take on diversity.The small earthquake activity is totally controlled by region stress field,and NWW horizontal principal comprehensive stress may help generate the strike-slip rupture of moderate and small faults with direction of NNW.

关 键 词：水库地震 瀑布沟水库 震源机制 应力场特征 

分 类 号：P315[天文地球—地震学]