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

Understanding how interseismic fault coupling relates to coseismic slip is essential to earthquake hazard assessment. On February 6, 2023, two major earthquakes (MW7.8 and MW 7.6) struck the Kahramanmaraş region along the Turkey-Syria border, rupturing 340 km of the East Anatolian Fault (EAF) and 150 km of the adjoining Çardak Fault (CF). We constructed a three-dimensional, 38-block kinematic model of Anatolia with high resolution triangulated dislocation element (TDE) mesh representations of the EAF and CF to quantitatively assess the spatial relationship between pre-earthquake coupling and coseismic slip. Using ∼50, 000 InSAR-derived velocities and bounded quadratic programming optimization, we estimated spatially variable coupling through distance-weighted eigenmodes over the TDE meshes. Pearson and Procrustes correlation analyses reveal notably higher correlation along the western ∼75% of the EAF rupture compared to the easternmost ∼25% of the EAF (east of the Sürgü fault intersection at 38.2◦ longitude). Alignment experiments demonstrate that the spatial offset required to maximize correlation between interseismic coupling and coseismic slip distributions varies systematically along strike, indicating that these patterns are laterally misaligned. For the set of kinematic models developed here, the interpretation of the correlation between coseismic slip and interseismic coupling remains equivocal.