Past century stress evolution and seismic hazards in the Haiyuan Fault in northeastern Tibetan Plateau: A case of the 2022 Menyuan MS6.9 earthquake

In order to reveal the stress-triggering mechanism of the 2022 Menyuan earthquake and quantitatively analyze the stress evolution of the Haiyuan Fault Zone over the century, we comprehensively consider the influence of co-seismic, post-seismic and inter-seismic effects of the earthquake cycle. The results show that the cumulative Coulomb stress at the rupture location of the 2022 Menyuan earthquake is 1.2495 MPa. The 1920 Haiyuan earthquake, the 1927 Gulang earthquake, and the 1954 Shandan earthquake caused the most significant stress loading, which exceeded the stress triggering threshold. The 2022 Menyuan earthquake occurred in the stress high-value zone at the western end of the Lenglongling Fault (0.6187 ∼ 1.5248 MPa), thereby further revealing the cause of the earthquake from a stress perspective; The co-seismic, post-seismic and inter-seismic stress accumulation at the source location of the 2022 Menyuan earthquake accounted for 30.17 %, 14.09 % and 55.74 % of the total stress accumulation, respectively. Therefore, it is necessary to comprehensively consider the effects of these three aspects; The western end of the Lenglongling Fault, the eastern section of the Jinqianghe Fault and the Maomaoshan Fault are in the high stress area, indicating high seismic risk. Under the action of creep and small earthquakes, the seismic risk of the Laohushan Fault is reduced. The Narrow Haiyuan Fault Zone is still in a stress unloading state due to the influence of the co-seismic rupture of the 1920 Haiyuan earthquake, and the future seismic hazard is low.