Assessment of tectonic activity using morphotectonic indices in Abhar-Lushan area, south of Alborz

The study area is located in the Tarom Sofla region, which is located in the central Alborz tectonic zone. Morphotectonic indices of the region provide useful and valuable variations, especially in determining tectonic activity. The tectonics of the region, which caused the bending of the Alborz belt in the study area, is one of the main factors controlling the morphotectonic indicators in the region. Alborz orogenic belt has important active faults around the Takestan bend which may affect the activity potential of the area. In this research, the tectonic activity of the region has been investigated by calculation of morphotectonic indices including stream length-gradient index (Sl), ratio of valley-floor width to valley height index (Vf), hypsometric integral index (Hi), drainage basin shape (Bs), stream sinuosity index (S), drainage basin asymmetry index (Af), transverse topographic symmetry index (T), and the planar surface density index (P). This study has been carried out using geological and topographical maps together with remote sensing of Landsat images, by using Arc GIS and Global mapper softwares. Finally, the results have been estimated using the evaluation of relative tectonic activity (Iat). The indicative values of Iat indicate high tectonic activity in the middle part, and moderate and low tectonic activity in the northwest and southeast part of the area, respectively.