Reza Mansouri; Amir Safari
Abstract
Parts of the earth's crust have tectonic motions in the present time and will be susceptible to danger in the future. Therefore, geomorphologicforms are very sensitive to the tectonic activities and change by this movements. The assessment of tectonic activities using some quantitative indicators ...
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Parts of the earth's crust have tectonic motions in the present time and will be susceptible to danger in the future. Therefore, geomorphologicforms are very sensitive to the tectonic activities and change by this movements. The assessment of tectonic activities using some quantitative indicators plays an important role in identifying these activities and helpsto interpret the tectonic condition of the areas
Research Methodology: In this research, indices such as Stream length gradient index (SL), Valley floor-valley height ratio (VF), Asymmetric factor (AF), Topographic inversion symmetry (T), Drainage basin shape ratio (BS), and meanders of rivers (S)have been used to determine the tectonic activities in Frahzad basin in north of Tehran metropolis. The research method is based on the analytical method. The Physical and conceptual tools used in this research include the topographic and geological maps of the study area, satellite images and GIS software in the form of ARC GIS 10. Also, the quantitative results obtained during several stages of fieldwork were evaluated Discussion and Results: This basin, with an area of 35.8 kilometersis one of the sub-basins of the mountainous area in north of Tehran city which is considered to be an appropriate place to evaluate the relative tectonic activity due to the occurrence of the foothill processes (mainly sliding and falling). Farahzad River of this basin comes from the eastern heights of Imam ZadehDavood.
Conclusion: The results of the research indicate that the Farahzad basin is in active status based on the SL, VF, AF, T, SMF, EU, FD and S indices, and is only in Semi-active status based on the BS index.
The analysis of these quantities in general indicate the activity of this basin in the present time and the basinis classified in Class 1 based on the IAT(Index of relative active tectonics)index. These results are consistent with geomorphological evidences including landslide occurrence in the region.
