Quantitative Analysis of Spatial Variability of Neo-tectonic Indices along the Sabzpushan Fault Zone within the Zagros Mountains

Abstract:

The evaluation of geomorphic indices of active tectonics using remote sensing and GIS offer an appropriate method to obtain quantitative data, which is crucial for determining the seismic potential of a fault zone in semiarid areas where tectonic rates are low-to-moderate and quaternary dating is limited. In this study, we investigate poorly understood Sabzpushan Fault Zone (SFZ) within the central part of the Zagros Mountains for spatial variability of neo-tectonic indices. This fault zone is characterized by differential uplift, high neo-tectonic signature and seismic activities in recent past. Field studies have revealed that the SFZ is dividable into three morpho-tectonic segments (northern, middle and southern) with en-echelon array. The neo-tectonic activity of each segment is obtained through DEM analysis using geomorphic indices including the mountain front sinuosity, hypsometric integral, asymmetry factor, stream length–gradient index and valley floor width to valley height ratio. The results illustrate differentiation in the states of activity between those segments at which the middle segment show the highest value. For instance, the mean value of stream-gradient index (SL) of the middle segment is 597.7, whereas this index is 387.5 and 535.4 for the northern and southern segments respectively. This pattern of variation is consistent with recent seismicity, preserved fault scarps, triangular facets and deeply incised valleys along the middle segment of the SFZ.