Mapping co-seismic surface deformation using high-resolution KOMPSAT-3/3A image correlation for the 2023...

Large earthquakes commonly generate surface rupture accompanied by both localized on-fault slip and spatially distributed off-fault deformation. Capturing both components is essential for understanding rupture processes and improving earthquake hazard assessment, yet field mapping alone often fails to fully document diffuse deformation. Here we evaluate the applicability of high-resolution Korea Multi-Purpose Satellite (KOMPSAT)-3 and -3A optical imagery for mapping near-field co-seismic deformation using sub-pixel optical image correlation (OIC), through two case-study areas affected by the 6 February 2023 Kahramanmaraş, Türkiye, earthquake sequence. We processed pre- and post-event stereo-mode KOMPSAT imagery using a MicMac-based workflow to generate orthorectified products and displacement fields, and compared the results with published Sentinel-2 OIC products and independent airborne Light Detection and Ranging (LiDAR) measurements. In the Hatay Airport area, KOMPSAT-3/3A OIC recovered a displacement pattern consistent with Sentinel-2, indicating ~5 m of relative motion across the fault, while the ~1 m effective spatial resolution enabled identification of localized infrastructure offsets (runway displacement) that were not detectable in 10 m Sentinel-2 imagery. In the Elbistan near-epicenter area, KOMPSAT-3/3A OIC resolved block motions of ~6 m and ~2 m in opposing directions. Swath profile analysis indicates an average on-fault slip of 6.8 m, whereas the total slip including distributed deformation reaches 9.3 m, implying that approximately 27% of the deformation is accommodated off-fault. Airborne LiDAR mapping provides an independent benchmark, with on-fault net slip of ~6.13 m and horizontal slip of 5.57 ± 1.40 m, consistent with the KOMPSAT-derived on-fault estimates and supporting the quantitative validity of the OIC results. However, the rupture geometry inferred from OIC is simpler than LiDAR-derived mapping, and absolute geolocation uncertainty remains a limiting factor with a post-correction Root Mean Square Error (RMSE) of 10.25 m and Circular Error with 90% Confidence (CE90) of 11.34 m, requiring cautious interpretation of absolute displacement magnitudes. Overall, our results demonstrate that KOMPSAT-3/3A imagery can serve as an effective resource for rapid rupture mapping and quantifying both on-fault and distributed deformation, while highlighting key requirements for improving geolocation control and integrating complementary datasets for robust three-dimensional deformation assessment.