Assessment of Relative Active Tectonics in the Bozgoush Basin (SW of Caspian Sea)

Abstract

Geomorphic indices are useful tools for studying relative active tectonics of a specific area. In this study, the relative active tectonics of Bozgoush region (NW of Iran) has been investigated based on Geomorphic indices. The studied indexes include: the stream length-gradient (SL), hypsometric integral (Hi), the ratio of valley floor width to valley height (Vf), the shape of the drainage basin (Bs), the sinuosity of mountain front (Smf), asymmetric factor of drainage basin (Af) and transverse topographic symmetry factor (T). In the present study, gathered data from various morphometric indexes of six basins are aggregated, and their obtained result is provided as relative active tectonics of the region or Iat index that shows a proper illustration of the relative active tectonics of the mentioned region. In order to develop a correct analysis of the mentioned area, the AHP (analytic hierarchy process) model with a studied weight, the final overlapped layer of relative tectonics is prepared with applying coefficients. With the comprehensive field studies, evidences like deep valleys, river bed immigration, landslides, sudden change in river cycles and surfaces of faults were found that are in good consistence with obtained data of relative active tectonics of the region. After measuring these indexes, it was found that Aydoghmush and OujanChay basins have a high relative active tectonics. With regard to the obtained results of present study, it seems that Tabriz fault has the most seismic and motional potential in northern basins of the region. In addition, in Aydoghmush basin, in southern part of the region, Qeynarjehchartagh fault has a high active tectonics that according to the estimated values has been identified as an active young structure in the region.