Abstract: The focal mechanism parameters of 262 small earthquakes recorded by Zipingpu reservoir earthquake monitoring network are calculated.The results show that the dominant strike of nodal planeⅠand rupture are in good consistency.There are reverse fault,normal fault,left-lateral and right-lateral strike-slip fault in the reservoir area and the percentage of strike-slip fault amounts to 45%.Of all the faults,66%are steep and 35%are almost vertical.As a result of the impact of reservoir impoundment, the strike-slip type faulting has obviously increased since 1 July 2006,and this type of faulting became dominant during the period of the reservoir earthquake swarm.

Key words: Zipingpu reservoir, small earthquake, focal mechanism solution, fault activity

摘要： 用紫坪铺水库专用台网的地震记录测定紫坪铺水库区262次小震震源机制参数,结果表明:节面I的优势方向与断裂走向展布一致性很好;库区地震断层有逆断层、正断层、左旋和右旋走滑断层,走滑断层占45%;库区断层66%陡峻,35%几近直立;受水库蓄水的影响,2006年7月1日后以走滑断层活动方式明显增多,水库地震群时段走滑断层活动方式表现突出。

关键词: 紫坪铺水库, 小地震, 震源机制解, 断层活动