Deep slip rates in the Anninghe fault and its surrounding regions according to repeating earthquakes

Based on broadband seismic data recorded by the Xichang Array and permanent seismic stations near the Anninghe fault from 2013 to 2019, similar earthquake clusters were identified by means of waveform correlation and the correction of P- and S-wave arrival times. By constraining interevent distances based on the difference between S- and P-wave arrival times, 10 groups of repeating earthquakes were identified in the Anninghe fault and its surrounding regions. Local events and repeating earthquakes in the studied area were relocated, and the recurrence interval of repeating earthquakes was used to estimate deep slip rates of the fault. It was found that slip rates in the southwestern section of the Wenchuan−Maoxian fault ranged from 4.37 to 6.09 mm/a. The slip rate in the northern segment of the Anninghe fault was 2.30 mm/a, and the slip rate in the Muli region ranged from 2.03 to 8.46 mm/a. It was thus inferred that the southwestern segment of the Wenchuan−Maoxian fault is continuously creeping, which is consistent with fault movements near seismogenic asperities. Therefore, a strong earthquake may occur in this area. Based on the identification of repeating earthquakes and earthquake relocation, it was concluded that the northern section of the Anninghe fault is creeping, while its southern section is locked. In the Muli region, shallow seismic events outnumber deep seismic events, and the shallow slip rate is higher than the deep slip rate, which is consistent with reservoir-induced seismicity.