关键词: 紫坪铺水库, 小地震, 震源机制解, 断层活动

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