Abstract:Taking the Aohanqi earthquake sequences as a case study, the seismic phase observation report of Inner Mongolia between 2018 and 2019 are used to relocate and analyze Aohanqi earthquake sequences by applying Hypo2000 location method as well as double difference location method respectively. It was concluded that the double difference location method has relatively higher locating accuracy among others. According to the results of double difference location method, the Aohanqi earthquake sequences has two concentrated distribution area which is located separately on the north and south sides of the Chifeng-Kaiyuan fault. About 73% of the earthquake is on the north side of the fault, and the epicenter is distributed in a strip along the NW-SE direction with an extension length of about 6.8km. The focal depth gradually became deep from west to east, and gradually became deep to shallow from south to north. However, the epicenter of the earthquakes on the south of the fault is clustered, with a maximum extension length of about 0.98km from south to north, and the focal depth showed no obvious variation along the east-west or north-south direction. The precise location results and the better understandings of the spatial distribution characteristics of the Aohanqi earthquake sequences can provide more accurate source parameters and references for the study of the seismogenic structure and the establishment of three-dimensional fine velocity structure in the region.