Focal mechanism of the Sheyang M_S4.4 earthquake on October 20, 2016 and the spatio-temporal distribution of the earthquake sequence

Based on the digital waveforms of Jiangsu seismic network, the focal mechanism of the Sheyang M_S4.4 earthquake was determined by using the CAP (cut and paste) method, and the M_L≥1.5 events of Sheyang earthquake sequence were relocated by using the HypoDD method. The result shows that the strike, dip and rake of the M_S4.4 event are 304°, 53°, 0° for the nodal plane Ⅰ, and 214°, 90°, 143° for the nodal plane Ⅱ, respectively, and the centroid depth is about 14 km. The relocation for the Sheyang earthquake sequence shows that the earthquake sequence was located between Hongze-Goudun fault and Yancheng-Nanyang'an fault with the predominant direction NW60° in horizontal space, and the sequence propagated from southeast to northwest with the focal depth of 6--23 km. According to the focal mechanism solutions and the relocation results, we deduce that the Sheyang M_S4.4 earthquake is a left-lateral slip event induced by shear rupture northwestwards under regional stress field, and its fault plane is nodal plane Ⅰ.