Revisiting the seismic hazard of surrounding faults following the 2021 Maduo (China) MW 7.3 earthquake based on the updated co-seismic slip model

Abstract

The 2021 M_W7.3 Maduo (Qinghai, China) earthquake occurred on the Kunlun Pass–Jiangcuo fault within the Bayan Har block. Due to limited observational data, discrepancies exist among published co-seismic slip models, which directly impact the seismic hazard analysis for surrounding faults. In this study, we jointly inverted the co-seismic slip model of the Maduo earthquake using co-seismic observations from campaign GNSS stations, regional continuous GNSS stations, and InSAR data. Our results reveal that the geometry of the rupture fault exhibits significant variation along its strike and comprises five distinct fault segments. The earthquake exhibits a peak slip of 4.0 m, with a seismic moment of 1.69 × 10²⁰ N m, corresponding to an M_W7.42. Constrained by this co-seismic slip model, we further investigated the co- and post-seismic Coulomb stress change of surrounding faults, employing a three–dimensional viscoelastic finite element model of the eastern Bayan Har block. Our findings indicate that the Maduo earthquake induced significant stress loading (>1.0 × 10⁴ Pa) on the Maqin–Maqu and Tuosuo Lake segments of the Eastern Kunlun fault, the southeastern segment of the Xizangdagou fault, etc. These findings, integrated with the elapsed time of historic earthquakes on both the Maqin–Maqu and Tuosuo Lake segments, which have approached or exceeded their recurrence intervals, underscore the need for increased attention to these fault segments.