The zoning of the relative morphotectonic activity of the Kan-Soleghan basin with an emphasis on the location of the Tehran-North Freeway tunnel

The Kan-Soleghan basin is located on the southern Hillside of the Alborz, which has affected the Alp-Himalayan active zone over time. In this respect, the evaluation of active tectonic processes and their effects on many human activities, such as the design and construction of cities, powerhouse, dams, industrial facilities are of great importance. The passage of the Tehran-North Freeway Tunnel from the area increases the activity of the faults that contributed to the formation of the current morphology of the basin. In this research, morphotectonic indices including river asymmetry index (Af), basin shape (Bs), hypsometric integral (Hi), Stream length index (Sl), mountain front sinusity (Smf), valley width to valley height (Vf), topographic symmetry (Tp) was calculated. Finally, the mean of the results of the indices was calculated as the LAT index. In the present study, topographic Map 1:50000 and digital elevation (DEM) maps with 30 m spatial resolution (ASTER sensors), The boundary layer of the basin, were used to calculate morphometric indices. The Kan-Soleghan basin area is divided into three tectonic regions with slow, semi-active, active Tectonic, and the calculation of the relative  Tectonic active (LAT) index indicates that the studied area is in tectonic terms in active state. The tectonic structures, especially the faults of the region, have affected the asymmetry and shape of the basin. The main river Kan-Soleghan also shows asymmetry, which can be said due to the structural factors, especially the faults of the region, the basin has asymmetry and deviation to the left of the basin. Also, the construction of the Tehran-north freeway and the location of the Tunnel openings in the vicinity of the northern fault of Tehran, is one of the human factors influenced by the tectonic activity of the area, which requires tectonic activity.