Abstract: According to the data of earthquake arrival time obtained from the Three Gorges network from 2001 to September 9, 2011, we employed the method of joint hypocenter determination to relocate 7011 earthquakes in the head region of Three Gorges area and obtained the station correction values in different stages of water storage. The results show that 1) earthquakes mainly occurred along the Yangtze River and concentrated at Guojiaba-Quyuanzhen, Xietan, and Badong-Wushan areas; 2) the lateral velocity in the head region of Three Gorges reservoir is inhomogeneous, and the velocity distribution is closely related with the geological structure and the condition of water storage; 3) the velocity structure in the head region of Three Gorges reservoir is mainly affected by geological structure before water storage, and is affected by geological structure and reservoir seepage during storage.This method has good effect for seismic location in the head area of the Three Gorges reservoir.

Key words: head region of the Three Gorges reservoir, joint hypocenters determination, station correction value, velocity structure, geological structure