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  • Kinematic Slip Evolution Du...
    Guo, Rumeng; Li, Luning; Zhang, Wenting; Zhang, Yijun; Tang, Xiongwei; Dai, Kun; Li, Yu; Zhang, Lupeng; Wang, Jingqi

    Geophysical research letters, 16 March 2023, Letnik: 50, Številka: 5
    Journal Article

    The September 2022 Ms 6.8 Luding earthquake broke more than 230 years of seismic calm on the Moxi fault, providing a unique opportunity to understand its seismogenic environment, rupture dynamics, and seismic hazard. Using teleseismic body waves, regional strong‐motion observations, GNSS, and InSAR data, we decipher the spatiotemporal rupture evolution of the mainshock. Combining the elastic dislocation model with surface creep, we find that the coseismic slip correlates closely with a locked patch with a loading rate of 9.7 mm/yr, but the creeping rate is insufficient to make up the shallow slip deficit. Notably, the Luding earthquake ruptured only ∼1/4 of the Moxi seismic gap, and it further increased the stress in the unruptured northern part. We thus argue that the Moxi fault has the potential for magnitude 7+ earthquakes in the near future, although geodetic prediction may overestimate the actual seismic moment released by the coseismic rupture. Plain Language Summary The Xianshuihe fault is an area of intense tectonic activity on the Tibetan Plateau and plays an important role in accommodating the postcollisional convergence of the Eurasian and Indian plates. However, the Moxi fault, at the southeastern end of the Xianshuihe fault, has remained seismically quiescent since the last Ms 7.75 event in 1786. In September 2022, a Ms 6.8 Luding earthquake struck the Moxi seismic gap, resulting in destructive landslide damage, with 93 people dead and 25 missing. Using seismic and geodetic recordings, we recover its space‐time rupture process in detail. Our model reveals an asymmetric bilateral rupture with dominant propagation and maximum slip to the SSE. It is important to note that the 2022 Luding earthquake ruptured only the southern Moxi seismic gap, leaving the northern part unruptured. Based on the departure time of the last major earthquake and the slip rate obtained from the elastic dislocation model, we estimate the unreleased seismic energy of the Moxi fault, indicating that it still has the potential for strong earthquakes. Besides, the Luding earthquake further increased its seismic hazard through stress transfer. Therefore, we should pay great attention to the kinematic state of the Moxi fault at this time. Key Points The kinematic evolution of the Luding earthquake is revealed by seismic and geodetic observations The coseismic slip asperity from 3 to 20 km depth correlates closely with the preseismic surface creep and locked patch The unruptured Moxi seismic gap still has the potential for magnitude 7+ earthquakes and deserves further attention