1. Introduction
The west-east trending strike-slip Qilian-Haiyuan fault system locates
in the northern margin of Qilian orogen in northeastern Tibet. It
extends approximately 1000 km from the west near the Hala Lake to the
east in Guyuan county in Gansu province, China (Yang et al., 2022). This
fault system composes of several fault segments: the Hala Lake fault
(HLHF), Tuolaishan fault (TLSF), Lenglongling fault (LLLF), Jinqianghe
fault (JQHF), Maomaoshan fault (MMSF), Laohushan fault (LHSF), and
Haiyuan fault (HYF) (Deng et al., 2007; Lasserre et al. 2002; Zheng et
al., 2013; Yang et al., 2022) (Figure 1). The recent Mw 6.6 Menyuan
earthquake with an epicenter of (37.828°N, 101.29°E) (the US Geological
Survey [USGS]) occurred in this fault system on Jan 8, 2022, which
caused damages to local high-speed rail lines (Peng et al., 2022; Yang
et al., 2022) (Figure 1). Field investigations indicate that this
earthquake produced a surface rupture of approximately 22 km
(https://www.cea.gov.cn/cea/xwzx/fzjzyw/5646200/index.html). Aftershocks
relocation and earthquake rupture modelling studies reveal that this
earthquake ruptured both on the eastern and western portions of the TLSF
and LLLF, respectively (Peng et al., 2022; Feng et al., 2022). The 2022
Menyuan earthquake located approximately 30–40 km west to another two
earlier Menyuan earthquakes (the 1986 Mw 6.0 and 2016 Mw 5.9 thrust
earthquakes in the Minyue-Damaying fault and north LLLF, respectively)
(Zhang et al., 2020; Peng et al., 2022; Yang et al., 2022) (Figure 1).
Peng et al. (2022) suggested that the 2022 Mw 6.6 Menyuan earthquake was
likely promoted by the 2016 Mw 5.9 Menyuan earthquake due to the stress
loaded on the 2022 earthquake rupture. However, the impact of the 1986
Mw 6.0 Menyuan earthquake on the 2022 Mw 6.6 Menyuan earthquake was
neglected in the earthquake stress calculation by Peng et al. (2022).
The reasons behind the 2022 Menyuan earthquake remain unknown.