2. Historical earthquakes
Together with the Altyn Tagh, Ganzi-Yushu-Xianshuhe, and Kunlun faults, the Qilian-Hiayuan fault system consists of the tectonic boundaries of the north and northeastern Tibet (Peltzer et al., 1988; Tapponnier et al., 2001). With the continuing south-north convergence between India and Eurasia plates, deformation along these major boundary strike-slip faults accommodates the eastward extrusion of the Tibetan Plateau by generating frequent large earthquakes in northeastern Tibet (Meyer et al., 1998; Wang et al., 2001). Geodetic data indicates that slip rates vary along the approximately 1000 km long Qilian-Haiyuan fault system, which are 1-2 mm/a, 4-6 mm/a, 3.4-6.4mm/a, 2.9-5.6mm/a, and 5 mm/a on the HLHF; TLSF; LLLF; JQHF-MMSF-LHSF, and HYF , respectively (Wang et al., 2020).
During the past century, the eastern Qilian-Haiyuan fault system generated 5 large earthquakes (M ≥ 5.9): 1990 Mw 6.2 Tianzhu (No. 7), 1986 Mw 6.0 Menyuan (No. 8), 2016 Mw 5.9 Menyuan (No. 9), 1920 Mw 8.5 (No. 10) Haiyuan, and 2022 Mw 6.6 Menyuan earthquakes (No. 12) (Tang and Wang, 1993; Liu-Zeng et al., 2007, 2015; Zhang et al., 2020; Peng et al., 2021; Yang et al., 2022). According to historical earthquake document, 7 historical large earthquake (M ≥ 7.0) occurred within the horizontal distance of less than 300 km from the Qilian-Haiyuan fault system from 1920 to 2022. This includes the 1932 Mw 7.5 Changma (No. 1), 1954 Mw 7.3 Shandan (No. 2), 1954 Mw 7.0 Minqin (No. 3), 1937 Tuosuo Lake (No. 4), 1963 Alake Lake (No. 5), 1990 Mw 7.0 Gonghe (No. 6), and 1927 Mw 8.5 Gulang earthquakes (Nos. 11) (Molnar and Deng, 1984; Gaudemer et al., 1995; Liu and Fu, 2001; Wan et al., 2007; Xu et al., 2002) (Figure 1). The detailed earthquake parameters are summarized in Table S1 (Supporting Information Text S1). In total, 12 historical earthquakes (Nos. 1-12 in Figure 1) were included in the ΔCFS calculations in this study.