Determinants of the Spatial Distribution of Lateral Spreading: February 6, 2023 Kahramanmaraş EarthquakeAuthors and Affiliations

The seismic event that occurred on 6 February 2023 in southeastern Turkey (Mw 7.8 and Mw 7.6) caused widespread surface deformation, with lateral spreading being the dominant process in fluvial environments. Despite the extensive research conducted on earthquake-induced lateral spreading, the majority of studies have focused on liquefaction mechanisms, with comparatively less attention being paid to the geomorphic controls on its spatial occurrence. This study aims to address this research gap by investigating the distribution of lateral spreading along the Asi (Orontes) River and identifying the key geomorphic factors that shape its development. To achieve this objective, a multi-source high-resolution dataset was compiled, incorporating pre- and post-earthquake satellite imagery, UAV-based optical data, and aerial photographs. These data were used to map 328 cases of lateral spreading. The sedimentological context of deformation zones was further constrained through stratigraphic profiling of exposed sedimentary sections. The results obtained revealed a pronounced clustering of lateral spreading on pointbar surfaces (58.6%), largely associated with convex planform geometries (49.4%). A secondary accumulation along cutbank–concave margins (25.5%) underscore the strong role of channel-margin morphology in conditioning susceptibility. The former Amik Lake floodplain stands out as the region where 68% of all cases occurred. Beyond its characteristic sedimentary properties, zones corresponding to the paleo-meander belt—particularly at intersections of abandoned channels also constitute weak geomorphic domains that facilitated lateral spreading. Additional controls, including distance to the fault rupture and channel sinuosity, likewise influenced the spatial pattern. By integrating these geomorphic and spatial parameters and situating the findings within a broader comparative context (e.g., the Canterbury earthquake), this study delineates the principal drivers governing lateral spreading as a secondary seismic hazard and advances our understanding of the geomorphic conditions that amplify its occurrence in active fluvial systems.