Mechanism of apparent resistivity changes before the 2024 Wushi <i>M</i> _S 7.1 earthquake in Xinjiang, China

A MS7.1 earthquake struck Wushi County, Xinjiang, China, on January 23, 2024. There is only one apparent resistivity station (i.e. Keping Station) in operation within 400 km of the earthquake. Significant precursory changes in apparent resistivity were recorded. The EW (EastWest) array showed a successive decline of 0.6% and a decrease of 0.5% in the NS (NorthSouth) array since April 2023. This study investigates the spatial distribution of stress and deformation before the earthquake using a fault virtual dislocation model and GNSS observations. Keping Station is located in an area of enhanced compressive deformation prior to the event. The direction of the maximum principal compressive stress estimated by the apparent resistivity anisotropic change is approximately 320° which is generally consistent with the P-axis orientation of 330° derived from the focal mechanism. Experimental and theoretical analyses have demonstrated that the resistivity of water-bearing rock and soil medium decreases under compressive stress loading and increases during stress unloading. The precursory apparent resistivity changes before the 2024 Wushi MS7.1 earthquake align with the experimental findings. Therefore, there may be a mechanical mechanism, that is regional deformation may cause resistivity changes, between the apparent resistivity anomalies and the late seismogenic process of the earthquake.