Catalog Replenishment Based on Statistical Method for Strong Earthquakes in the Triple Junction Area, Eastern Tibet

Abstract The triple junction area, bordered by the Longmenshan, Xianshuihe, and Anninghe faults, is located at the southeastern corner of Songpan–Ganzi block, northern Tibet. In this area, a series of strong earthquakes occurred, including the 2008 Mw 7.9 Wenchuan, 2013 Mw 6.6 Lushan, 2014 Mw 5.9 Kangding, 2022 Mw 5.8 Lushan, and 2022 Mw 6.6 Luding. In addition, multiple hot springs with different temperatures are distributed along the faults in the same area. This study tries to figure out: (1) the necessity of catalog replenishment based on statistical method; (2) whether the special tectonic environment characterized by hot springs influences the evolution of aftershock sequences. A complete aftershock catalog is a fundamental data set for exploring these issues. However, the incompleteness of the catalog limits our understanding of aftershock evolution. Here, we applied a statistical catalog replenishment method to the five aftershock sequences, with the results showing that the replenishment method is helpful to improve the catalog completeness by producing more reasonable Omori law parameters. In addition, both the catalogs obtained from matched filter technique and the replenishment method have advantages and limitations, suggesting that combining two versions of catalog in aftershock evolution study is helpful. Finally, we revealed a negative correlation between the p-value of Omori law parameters and temperatures of hot springs, which may be useful to evaluate potential aftershock risks.