Slip-weakening distance and energy partitioning estimated from near-fault recordings during the 2023 Mw 7.8 Türkiye-Syria earthquake

Fault-weakening process governs the earthquake rupture dynamics and energy partitioning and is of great importance for understanding earthquake physics and seismic hazards. The 2023 Mw 7.8 Türkiye-Syria earthquake was well recorded by dense strong motion stations near ruptured faults, providing a rare opportunity to explore parameters controlling the fault-weakening behavior. This work investigates the Dc″ value as a proxy of the slip-weakening distance, defined as double the fault-parallel displacement at the time of peak ground velocity. The Dc″ values are directly estimated from observations of near-fault stations whose final displacements are carefully corrected from original acceleration recordings and validated by coseismic horizontal displacements from geodetic techniques. Our results show that estimated Dc″ values ranging from 0.9 m to 2.4 m are spatially variable and generally follow the scaling relationship of Dc″ versus the final slip, consistent with previous observations. We also analyze the earthquake energy budget based on a well-constrained finite-fault model. The results reveal that the radiation efficiency of the event is relatively low and may not favor the sustained generation of supershear rupture. These results provide important insights into heterogeneous frictional properties on natural faults and implications for seismic hazard assessment.