Tempo-spatial characteristics of repeating seismic events in the middle of Tianshan orogenic belt

Abstract

Based on the seismic waveform data recorded in the stations of the Xinjiang seismic network from 2009 to 2017, the repeating earthquakes in the middle of Tianshan orogenic belt and its periphery in Xinjiang were determined and relocated by using the waveform correlation technique and the master event approach. The results show that 11 618 of the 30 181 events are repeating events, which consist of 2395 groups of doublets and clusters, accounting for 38.5% of the total events. According to the statistical results of the distance between doublets before and after repeating events relocation, it is estimated that the system location error in the research area is about 5—10 km. In addition, combined with the latest source classification results in this area, the results show that repeating earthquakes of different source types have different spatial and temporal distribution characteristics. Repeating quarry blasts appear mostly as clusters, 93.6% of them occur during the daytime, and they also exhibit a seasonal pattern with more events in summers and fewer ones in winters. Tectonic earthquakes occurred in various thrust faults in the Tianshan orogenic belt, and occurred randomly at any time of the day, and the monthly tectonic event frequency is relatively stable during the studied period. Repeating induced earthquake locations indicate that most of them are located near large gas/oil fields and water reservoirs, but some also geographically overlay tectonic earthquakes in some regions. The occurring time characteristics of induced earthquakes are similar to those of tectonic earthquakes, that is random distribution within 24 hours.