Coseismic Surface Rupture Zone Widths of the 2021 M w 7.4 Maduo Earthquake in the Tibetan Plateau: Insights Into the Earthquake Dynamic Rupture Processes

Abstract The coseismic surface rupture zone width (RZW) is a fundamental parameter for characterizing surface ruptures produced by earthquake dynamic rupture propagation, yet its potential to record earthquake dynamic rupture processes has been largely overlooked. Here, we investigate the surface RZWs of the 2021 M w 7.4 Maduo strike‐slip earthquake in the Tibetan Plateau. Using high‐resolution (4–8 cm per pixel) drone orthoimages, we measure surface RZWs at 100 m intervals along the entire ∼148 km surface rupture of Segments 1–4. We find that although local surface RZWs can be influenced by fault geometric complexities and overlying soil conditions (e.g., thickness and fracture toughness), macroscopic surface RZW distributions reflect earthquake dynamic rupture processes. At the local scale, fault stepovers and branches increase RZWs more than fault bends do. Surface ruptures are widespread within releasing fault stepovers but are nearly absent in restraining stepovers. At the macroscopic scale, particularly in Segments 1 and 2 west of the epicenter, surface RZWs increase with rupture propagation distance, which we link to progressively growing fracture energy dissipated off‐fault with rupture propagation distance within a high‐slip region. East of the epicenter, Segment 3 features a distinct narrowing of the RZW, which we interpret as the location of the supershear transition, triggered by an extensional fault bend that reduced normal stress dynamically and elevated shear prestress. Segment 4 contains more extensive secondary cracks than Segments 1–3, which we attribute to fault intersections, greater fault roughness, wider damage zones, and the rupture‐stopping phase.