Relocation and source characteristics of the 2019 Changning M_S6.0 earthquake sequence

The double difference earthquake location algorithm is used to relocate the earthquakes occurred in Changning area of Sichuan Province, which recorded by Sichuan regional network from January 1, 2019 to October 20, 2019, 7030 relocation events were obtained, and showing the clearer spatial distribution of Changning M_S6.0 earthquake sequence. The average b-value of Changning focal area is calculated with relocated aftershocks catalog, and the seismicity of the earthquake sequence is analyzed. The focal mechanism solutions and centriod depth of the Changning main shock and 4 aftershocks with M_S≥5.0 have been inverted with the local full-waveform inversion method, and the seismotectonics of this earthquake sequence was analyzed preliminarily. The main conclusions are as follow: ① The Sichuan Changning aftershocks distribute in a NW−SE trending, and the aftershocks show a trending of deep in the West and shallow in the East, and the frequency of earthquakes in the western part is much higher than that in the eastern part; ② The spatial distribution of b-value shows obvious compression tectonic environment in the Changning area after the occurrence of the earthquake; ③ The main shock and 4 moderate aftershocks occurred at unusual shallow centroid depths, and their focal plane solutions suggest that earthquakes occurred on thrust faults with slightly different strike; ④ It is speculated that the M_S6.0 main shock and moderate aftershocks occurred on the preexisting faults, which subjected from a long-term compression force and the earthquake happened when the stress beyond the elastic limit, or the aftershocks generated on the newly generated faults created by mainshock coseismic rupture in Changning anticline area.