Multisensor Observations of Shallow Rupture and Surface Deformation of the 2025 Mw 5.4 Xinlong Earthquake on a Previously Unmapped Normal Fault in the Eastern Tibetan Plateau

Abstract The surface expression of moderate earthquakes is often subtle and localized, requiring observations across multiple spatial scales to fully characterize. Here, we investigate the 2025 Mw 5.4 Xinlong earthquake in the eastern Tibetan plateau using multisensor geodetic and geological observations, including Synthetic Aperture Radar interferometry, optical correlation, unmanned aerial vehicle photogrammetry, field mapping, and seismological constraints. Interferometric Synthetic Aperture Radar reveals up to ∼7 cm coseismic line-of-sight deformation, with localized surface displacement discontinuities of up to ∼4 cm across the inferred rupture trace. Geodetic inversion indicates predominantly normal-faulting slip concentrated at shallow depths of 1.4–5.7 km, consistent with seismological depth estimates of ∼5 to 7 km. Integrated surface deformation, coherence loss, and geomorphic evidence delineate a shallow rupture-related deformation zone along a previously unrecognized east-northeast–west-southwest-trending normal fault. These results demonstrate that multisensor observations across different scales can effectively constrain shallow rupture-related deformation associated with moderate normal-faulting earthquakes and reveal active localized extension associated with tectonic extrusion in the eastern Tibetan plateau.