Morphotectonics of Alborz Province (Iran): A Case Study Using GIS Method

Abstract

The most active tectonic areas based on morphotectonic indices is the main aim of this study, are characterized. Mechanical deformation resulting mostly from the Arabia-Eurasia collision is amalgamated by the Alborz Mountains in the form of folding and faulting. The proposed area includes the Alborz province in northern Iran as part of the Alborz mountain range that has seismogenic faults and large earthquakes. Therefore, the basins’ morphologies and shapes are associated with tectonic activity. In this study, the morphometric indices of valley height-width (Vf), asymmetry factor (Af), basin shape (Bs), topographic symmetry factor (T), hypersonic curve (Hc), hypersonic integral (Hi), and river sinuosity (S) were measured for the 33 number basins to assess tectonic activity. Using indices of related active tectonics (IRAT) and weighting and combining morphometric indices, a map was prepared that showed an eye-shaped area at the center of the study area (Hashtgerd) that had high tectonic activity. The tectonic setting survey specified a crush zone because of the collision of active faults near Hashtgerd. A comparison of field observations clearly indicated that the highly active eye-shaped area had a good correlation with the crushed zone and hypocenter of large earthquakes.