Super‐Shear and Generalized Rayleigh Rupture of the 2023 Turkey Earthquake Doublet Influenced by Fault Material Contrast

Abstract Rupture speed is a crucial parameter of earthquake dynamics and influencing associated seismic hazards. Accurately resolving the rupture evolution of large earthquakes is essential for identifying factors governing earthquake physics. In this study, we investigate the kinematic rupture processes of the 2023 Mw7.8 and Mw7.7 eastern Turkey earthquake doublet. We integrate various complementary data sets and methods, including 3D surface deformation, teleseismic back‐projection, near‐fault strong motion waveform analysis, and finite fault inversions, to resolve the rupture details. Our results reveal that the Mw7.8 earthquake predominantly involves an asymmetric bilateral rupture on the main fault, with part of the northeastward rupture reaching super‐shear speed (∼5.2 km/s), while the southwestward rupture propagates primarily at the generalized Rayleigh speed (∼3.4 km/s), a characteristic of an inhomogeneous fault zone separating two dissimilar materials. This directional dependence on rupture speed may be attributed to a material contrast between the softer Anatolian plate and the stiffer Arabian plate, as supported by the fault zone head wave observations and tomography models. In contrast, the Mw7.7 event features a bilateral super‐shear rupture, likely due to its occurrence on intraplate faults without substantial material contrast across the fault. This study underscores the importance of incorporating detailed fault zone structures and high‐quality near‐fault observations into earthquake physics and seismic hazard analysis.