Analyzing the effects of tectonic and lithology on the occurrence of landslide along Zagros ophiolitic suture: a case study of Sarv-Abad, Kurdistan, Iran

Assessment of the landslide susceptibility can provide useful information in the management and mitigation of the negative consequences of this phenomenon. The purpose of this study was to map the landslide susceptibility and to highlight the effects of tectonic and lithology. The landslide-causing factors including distance from faults, lithology, slope gradient, slope aspect, distance from drainages, distance from roads, land use, and precipitation were used for the landslide susceptibility mapping by using analytical hierarchical process (AHP) method. Based on the landslide susceptibility zonation map, the study area was grouped into five susceptibility classes including very low, low, moderate, high, and very high. High values of landslide density in very high and high susceptible zone, and the high percentage of area under the success rate curve (72.65%) show that the AHP method has accurately predicted the landslide susceptibility zonation map of the study area. Data reveal that most landslides are close to the Zagros Main Recent Fault (MRF) and the Main Zagros Reverse Fault (MZRF) that merge with each other along the trend of Azad River. These faults have locally produced zones of extension and contraction that have caused the intense faulting and fracturing of rocks and hence the intensification of the landslides. The Oligo-Miocene marl (with high potential of plasticity, expanding, and cracking), the Oligo-Miocene limestone (with steep dip slopes and strike-slip faults) that overlies the Oligo-Miocene marls as a lubricant, and serpentinites (with high capacity of flexibility, plasticity, and sheeting) are three important lithological units that are more prone to landsliding.