Spatial relations between pre-event interseismic fault coupling and coseismic fault slip associated with the 2023 Turkey-Syria Earthquake sequence.

On February 6, 2023, two significant earthquakes (MW 7.8 and MW 7.6) impacted the Kahramanmaras region, rupturing 340 km of the East Anatolian Fault (EAF) and 150 km of the Cardak Fault (CF). To investigate the relationship between pre-event fault coupling and coseismic slip, a three-dimensional kinematic model comprising 38 blocks was developed, incorporating mesh-based representations of the EAF and CF. The model utilizes approximately 50,000 InSAR velocities and represents slip rates using distance-weighted eigenmodes. Coupling is estimated through bounded quadratic programming. Pearson and Procrustes analyses are employed to compare pre-event coupling with observed coseismic slip. Along the western, approximately 75% of the EAF rupture, correlation is higher than in the easternmost 25% (east of the Surgu fault at 38.2 degrees longitude). Alignment tests indicate that the offsets required to maximize correlation vary along the fault, suggesting imperfect alignment of kinematic model patterns. Consequently, the actual correlation between coseismic slip and interseismic coupling remains equivocal.