Abstract: Using the double-difference earthquake location algorithm, we relocated hypocenters of 539 earthquakes for the Shuikou reservoir M_L4.8 earthquake sequence in Fujian, reduced the location residuals, obtained the fine earthquake activity images. Spatial and temporal characteristics of the earthquake sequence was discussed. We concluded that: ① Epicenter moving image shows a banded distribution trending north west, 4.5 km wide in north-west and 2.9 km wide in north-east; ② Foreshocks mainly occurred in the reservoir shore, in the intensive phase, aftershocks occurred mainly in the reservoir waters, the late decay of aftershocks occurred mainly in the reservoir shore, forming a shore-water-shore migration process; ③ Focal depth profile of North-West show that the depth from the shore to the water gradually deepened, in time, the focal depth experienced a deep-shallow-deep process. At last, combining the largest foreshock and the largest aftershock focal mechanisms, and the local geological background, we speculated that the seismogenic structure of this sequence should be the Minjiang fault.

Key words: Fujian Shuikou reservoir, Earthquake sequence, Double difference location method