Evaluation of the Relative Tectonic Activity of the Yeşilyurt Fault Using Morphometric Analyses

The Yeşilyurt Fault (YF) is an approximately 70 km long, NE–SW-trending, left-lateral strike-slip fault located in eastern Türkiye and constitutes a major structural element for assessing regional seismic hazard in Malatya Province. This study integrates multiple morphometric indices to quantitatively evaluate the spatial variability of tectonic activity along the YF and its associated drainage basins. Morphometric analyses were performed using mountain-front sinuosity (Smf), valley floor width–valley height ratio (Vf), hypsometric curves (HC) and hypsometric integrals (HI), asymmetry factor (AF), and stream length–gradient index (SL). These indices were applied to drainage basins distributed along four fault segments (S1–S4) to assess relative tectonic activity, uplift, basin tilting, and landscape evolution. Additionally, empirical fault length–magnitude relationships were used to estimate the seismic potential of individual segments and the entire fault zone. The results indicate that the S1, S2, and S3 segments are characterized by moderate to relatively high tectonic activity, reflected by moderate Smf and Vf values, elevated SL indices, and uplift rates ranging from 0.05 to 0.5 mm/yr. In contrast, the S4 segment exhibits comparatively lower tectonic activity, with uplift rates below 0.05 mm/yr, likely influenced by enhanced erosional processes and extensive alluvial fan development. Hypsometric analyses reveal pronounced spatial variability in basin evolution, ranging from youthful to mature and old geomorphic stages, while AF results indicate that approximately 80% of the drainage basins display asymmetric geometries, suggesting active tectonic tilting. The calculated relative tectonic activity (Iat) indices further confirm that the S1, S2, and S3 segments exhibit high tectonic activity, whereas the S4 segment is characterized by moderate activity. The occurrence of the Mw 6.0 earthquake on 6 October 2024 confirms the present-day activity of the YF, and when integrated with morphometric results and empirical estimates indicating a potential Mw ~7.2 earthquake in the case of full-fault rupture, the YF represents a significant seismic hazard for the region.