Relative Assessment of active Tectonic by Morphometric Methods in North and East Basins of Sahand Mountain

The study of active tectonics, and in particular those earas with relatively high activity in the Holocene and late Pleistocene is important to evaluate the earthquake hazard. In this study active tectonics of drainage basins in the east and north of Sahand Mountain, were assessed through morphotectonic analysis. Indexes used in this study include: ratio of valley-floor width to valley height (Vf), stream length–gradient index (Sl), drainage basin asymmetry (Af), index of drainage shape (Bs) and index of mountain from sinuosity (Smf). Results of analysis were expressed as an index of relative active tectonics (Iat). For eastimating active tectonic in the study region we used topographic maps (1: 50000, 1: 250000) and geological maps (1: 100000, 1: 250000). This index showed active tectonics of the area in four classes of low, medium, high and very high magnitude. The results of study showed that Saeed Abad- Chai, Kalgan-Chai and Almaloo-Chai have high tectonic activity. In other basins, the points of active tectonics are moderate. The north basins are affected by Tabriz fault.