Abstract:For this study, we collected one thousand seismic events that occurred in Jiangsu province from 2009 to 2015. Four earthquake sequences occurred successively in this area:Jianhu earthquake sequence, 2011; Gaoyou earthquake sequence, 2012; Guanyun earthquake sequence, 2013; and Donghai earthquake sequence, 2015. We relocated these earthquakes using a double-difference location algorithm. For this analysis it was crucial to establish a reasonable crustal structure therefore, because the double-difference location result was affected by the horizontal velocity model, a more accurate model was required. This paper references the initial model of crustal velocity in Jiangsu and its adjacent regions established by Huangyun. In order to increase the total number of precise location generation events in different areas, this research divided Jiangsu province into seven small areas, and relocated the earthquakes for each. Because the distribution density of the recording stations is different, the number of earthquakes in each area is different. The results show a significant improvement in the relocation results, and the earthquake sequences were found to be more spatially concentrated. The relocated earthquakes were concentrated in obvious bands around faults, and most of them occurred at depths of 5~20 km, suggesting the seismological layer in the region lies in the mid-upper crust. By analyzing the seismic tectonic activity of these earthquake swarms, we were able to investigate:the trend of each earthquake sequence, whether or not a new fault zone was initiated, and whether the trends of the new fault zones were consistent with the old ones. This is of great significance to future studies in this area.