Investigation of the active tectonic in Semnan basin (South of Semnan) using geomorphological indices

Geomorphological indicators are known as very useful methods for evaluating the effects of slow and fast tectonic activities. These indices can be used to compare different land forms in real and reasonable terms. This research aims to shed light on the mechanism and effectiveness of tectonic movements in Semnan basin using such geomorphic parameters as stream length-gradient, hypsometric integral, ratio of valley floor width to valley height, reverse topographic symmetry, drainage basin asymmetry, main river crinkle, mountain front simosity, drainage density, bifurcation ratio, and basin shape. These parameters serve as the model concepts. The physical devices used in this study included IRS satellite images, topographic maps, geological maps, and a geographic information system. To conduct the research, a digital evaluation model was designed for the study area using SRTM10m topographic data. Then, by means of the ARCMAP software, streams were delineated, the indices were measured, and statistical analyses were performed of the parameters. The results were obtained in the form of a map. The results of the data analysis according to the geomorphological indexes and the use of physical tools show that the tectonic activities in the area are moderate. Calculation of 10 geomorphic parameters in the study area represents a relatively active neotectonic activity in Semnan basin. According to the IAT index classification, Semnan basin can be placed in class 3 in terms of tectonic activities. The deep v-shaped valleys in the northern part of the region serve as evidence for such activities in the basin.