Abstract:Earthquake swarm activities have been occurring in the Xianyou area of Fujian Province since August 2010. The level of seismic activity increased in 2012 and further increased in 2013, when ML ≥ 3.0 earthquakes were concentrated. Sufficient observation data of these earthquakes were recorded by Fujian digital seismic network. In this study, the sequence of ML ≥ 1.0 earthquakes are relocated using the P-and S-wave arrival data, and it is found that both the spatial location and focal depth of the earthquake sequence show different distribution characteristics for different periods. Meanwhile, based on the waveform data recorded by Fujian digital seismic network, the focal mechanism solutions and the best focal depths of ML ≥ 3.5 earthquakes are obtained with the "cut and paste" method. According to the characteristics of earthquake swarm sequence, distribution of hypocenter location and fault activity in the hypocentral region, and the focal mechanism solution, it is concluded that the Xianyou earthquake swarm sequence are tectonic earthquakes caused by reservoir water infiltration and then fault slip, and thus, they are reservoir-induced tectonic earthquakes; in addition, the seismogenic structure is the NW-trending Shicang fault which passes through the reservoir area.
