Investigation of the relationship between tectonic morphological indices and seismic acceleration in Indes, Aipak, Avaj and Kushk-e-Nusrat fault zones (northwest of Saveh)

The northwest zone of Saveh city is located in the Indes , Kooshk e Nosrat, Avaj and Ipak fault zones. Indes, Kooshk e Nosrat, Avaj and Ipak faults are considered as the major faults in central Iran, which are also active in the Quaternary and the their last movements are attributed to the present time, therefore, the estimation of morphometry in order to identify the effect of active tectonics on the tectonic evolution of drainage basins seems necessary. Therefore, in this study, six important morphotectonic indices were analyzed including longitudinal gradient of the river, asymmetry of drainage basin, hypsometric integral, Drainage basin shape, the ratio of the floor width to the valley height and mountain front. In order to model the formation of basins in the studied area, Arc Hydro software (Arc GIS add ins) has been used based on data derived from a digital elevation model. Then, ۶ morphotectonic indices have been compiled and classified on each of the basins. Finally the Active Tectonic Index (IAT) has been calculated, according to which the study area has been classified into ۴ categories including very high, high, intermediate and low tectonic activity. According to the IAT index, ۵% of the study area shows very high tectonic activity, ۲۵% of the studied area has high tectonic activity, ۶۵% of it has the average tectonic activity and about ۵% of the tectonic activity are low. In this study, the highest level of tectonic activity can be seen in the north-eastern part of the area. In most sectors, the level of activity is high and intermediate, which is related to the activity of Kooshk-e-Nosrat, Aipak and Avaj faults.The northwest zone of Saveh city is located in the Indes , Kooshk e Nosrat, Avaj and Ipak fault zones. Indes, Kooshk e Nosrat, Avaj and Ipak faults are considered as the major faults in central Iran, which are also active in the Quaternary and the their last movements are attributed to the present time, therefore, the estimation of morphometry in order to identify the effect of active tectonics on the tectonic evolution of drainage basins seems necessary. Therefore, in this study, six important morphotectonic indices were analyzed including longitudinal gradient of the river, asymmetry of drainage basin, hypsometric integral, Drainage basin shape, the ratio of the floor width to the valley height and mountain front. In order to model the formation of basins in the studied area, Arc Hydro software (Arc GIS add ins) has been used based on data derived from a digital elevation model. Then, ۶ morphotectonic indices have been compiled and classified on each of the basins. Finally the Active Tectonic Index (IAT) has been calculated, according to which the study area has been classified into ۴ categories including very high, high, intermediate and low tectonic activity. According to the IAT index, ۵% of the study area shows very high tectonic activity, ۲۵% of the studied area has high tectonic activity, ۶۵% of it has the average tectonic activity and about ۵% of the tectonic activity are low. In this study, the highest level of tectonic activity can be seen in the north-eastern part of the area. In most sectors, the level of activity is high and intermediate, which is related to the activity of Kooshk-e-Nosrat, Aipak and Avaj faults.

کلیدواژه ها:

Active tectonic ، Morphometric Indices ، Kooshk-e-Nosrat fault ، Indes fault ، Avaj fault ، Ipak fault ، Central Iran