Seismogenic structure of the M(S)6. 2 Taiwan strait earthquake on 26 November, 2018

Based on the broadband record of 17 stations from Fujian seismic network,Guangdong seismic network and Taiwan Central Weather Bureau, We obtained the focal mechanism of the M(S)6. 2 earthquake with the "Cut and Paste" (CAP) method, The results show that the best-fit moment magnitude and focal depth are M(W)5. 8 and 14 km respectively. One nodal plane of the best double couple solution of the mainshock is 89, 82 and 173 for strike, dip and rake angles respectively, while the other nodal plane is 358 degrees, 84 degrees and -7 degrees. We also obtained 94 relocated events by applying double-difference location method. The hypocenter of the mainshock is 23. 36 degrees N, 118. 62 degrees E with the focal depth of 10. 43 km. According to the distributions of earthquake sequence and tectonic stress field, the synthetical fault plane of aftershocks is 88 degrees and 60 degrees for strike and dip angle respectively. The research suggests that, the seismogenic structure of the n6. 2 Taiwan strait earthquake is Taiwan shoal fault, this fault with near E-W trending is formed due to the tension rifting of South China Sea subplate. Under the background of collision and compression in NW direction between Philippine plate and Eurasian plate, the Taiwan shoal fault and the Dongshan uplift Eastern fault intersect in the seismic area, which reduces the frictional strength of the faults. Under the continuous pushing of the Philippine plate, a rightlateral strike-slip dislocation with high dip angle occurred in the Taiwan shoal fault, which triggered the n6. 2 earthquake, then the aftershocks distribute along the Taiwan shoal fault.