Morphotectonic Analysis of Sub‒Basins along the North Termination of Anar Fault, Yazd Block, Iran

Abstract

The morphotectonic analysis is a significant tool to assess the tectonic activity in the study area. The Anar fault system with strike-slip mechanism and length of ~200 km associated with numerous minor faults represents an important tectonic feature in the Yazd block. Despite the lack of data of large earthquakes (M ≥ 4.5) along the Anar fault system (AFS), there is much notable Quaternary geomorphic evidence which highlight its recent tectonic activity. In our study we used geomorphic indicators such as drainage basin Asymmetry Factor (Af), Stream Length-gradient index (SL), the ratio of valley floor width to valley height (Vf), Basin Shape factor (Bs), and relative index of active tectonics (Iat). Based on results of Iat measures, the tectonic activity of the Anar fault system is higher in the central part (with Iat class from 1 to 2), in comparison with the margins of the study area. This clearly shows that the geomorphic characteristics in the region have been affected by the tectonic activity of the Anar fault system. The morphotectonic analysis carried out to enlighten possibility of reconstruction tectonic activity evidence in the areas with lack of earthquake data.