Quantitative analysis of the relative tectonic activity of the Almus fault zone, Tokat, Türkiye

The Almus Fault Zone (AFZ) is one of the major splay faults of the North Anatolian Fault Zone (NAFZ) and is important for understanding its tectonic features and assessing regional seismic hazards. This research presents the integration of morphometric indices to quantitatively assess the spatial variation of tectonic activity along the AFZ. The AFZ is an active fault with both strike-slip and normal fault components and consists of two main branches, Mercimekdağı-Çamdere Fault (MÇF) and Tokat Fault (TF) segments. This study aims to assess the relative tectonic activity of the AFZ using various morphometric indices, based on a 10 m resolution DEM, with the aid of ArcGIS and MATLAB software. For this purpose, morphometric indices such as hypsometric integral (HI: 0.35-0.65), mountain front sinuosity (Smf: 1.3-1.44), valley floor width-height ratio (Vf: 0.15-2.28), asymmetry factor (AF: 23-77), drainage basin shape (Bs: 1.13-6.10) and normalized steepness index (ksn: 1-498) were applied to 53 drainage basins. When the Smf and mean Vf indices results were evaluated, it was calculated that the uplift ratio of the region was more than 0.5 mm/yr. The spatial distribution of the relative tectonic activity (Iat) of the area was revealed by combining the obtained morphometric indices analysis results. According to the Iat result, it was concluded that the Mercimekdağı-Çamdere Fault and Tokat Fault segments have high tectonic activity, but the Mercimekdağı-Çamdere Fault segment has higher tectonic activity. The results obtained were also confirmed by field observations. This research provides valuable information for the evaluation of tectonic activity in drainage systems controlled by splay faults.