Determination of Tectonic Activity Based on the Morphology of Alluvial Fan Systems (Case Study: the Northern Slopes of Sabalan Volcanic Mount)

Aims & Backgrounds Alluvial fans are one of the most prominent phenomena in fluvial geomorphology, which are found mostly on the mountain front.These landforms are affected by climate change and tectonic activity and record their effects.Therefore, we can use them to understand climate change and tectonic activities in the past and at the present.The aim of this study was to determine the tectonic activity in the northern front of the Sabalan mountain based on the morphology of alluvial fan systems.By conducting such studies, it is possible to identify active processes on alluvials and, thereby to some extent, prevent the damage to life and property due to natural disasters, in particular earthquakes and floods.Methodology To do this, the geomorphic indices of related to cachments such as RLP (Real Long Profile), TLP (Theoreitical Long Profile), ILP (Incision Long Profile), Stream Concavity Index (Sci), Asymmetric Factor (Af), Hypsometric Curve (Hc), Hypsometric integral (Hi), Drainage Basin Shape (Bs), Relief Ratio (Rr) were used.Moreover, field observations, digital elevation model, GIS, and Arc Hydrow were used. FindingsThe subsidence of the central part of the Sabalan mass during the quaternary period was accompanied by the formation of a circular fault (caldera) and other sub-faults in the apex of the fan systems.These faults, in addition to the uplift of the fans apex and lowering the base level of them, by creating longitudinal valleys and channelizing the surface currents, cut the lahar flows at the head of the fan systems.Conclusion Morphology of the fan systems in the study area was active.In addition; the rule of glacial periods during the eruption of the Sabalan volcano, with generation of Lahar flow, played a decisive role.