Quantitative assessment of relative tectonic activity in the Alamarvdasht river basin, south of Iran

Tectonic processes are major factors controlling landform development in tectonically active areas. In order to evaluate quantitative measurement of tectonic activities in the Alamarvdasht basin in the south of Iran, six different morphological indices including stream-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), valley floor width-valley height ratio (Vf), drainage basin shape (Bs) and mountain-front sinuosity (Smf) were calculated. These indices were combined to generate the relative active tectonics index (IAT) and the study area was divided into three classes: high, moderate and low relative tectonic activity based on IAT values. The results of IAT index showed that high and moderate tectonic activity areas are located near the main faults and anticlines. The results are also consistent with geology and field observations on landforms and GPS data of Lamerd geodynamics station. GPS data shows subsidence and north-eastern movement in the basin because of convergence between the Arabian and Eurasian plates in the Zagros Mountains zone.