Study of landslide potential in Chaybagh region with 2D electrical resistivity tomography method

Landslides are natural hazards that cause severe fatalities and financial losses. Various methods are used to analyze landslides. Among those, geotechnical and geophysical methods are used due to their accuracy and low cost, respectively. In geophysical methods, electrical resistivity tomography (ERT) is widely used for near-surface exploration of landslide areas characterized by a complex geological environment. In this study, two-dimensional electrical resistivity tomography (ERT) studies have been used to define the subsurface structure and landslide geometry of Chaybagh. Over the past decade, technological advances in field data acquisition systems and the development of new algorithms for tomographic inversion have made this technique more suitable for studying landslide areas. In order to reduce the possible damages in the preliminary studies of construction projects, especially linear structures, it is very important to study the areas with slip potential.Following the widening the road in a part of Sari-Shirgah road in the Chaybagh area of North Savadkuh County, which overturned a freight train downstream due to bending of railway tracks, a large gap was created. In order to determine the cause of this accident and the possibility of landslides in the area, 2D geoelectric tomography was performed and necessary considerations were taken into account for reconstruction of the new road to prevent further damages.According to the geological map of Ghaemshahr 1/100000, the study area includes conglomerate, silty marl, sandstone and siltstone. At the bottom of the landslide area is the Talar River bed, which includes alluvial fans, floodplains, old and young rivers and streams, alluvial floodplains, older coastline deposits, and non-hardened alluvium of the present age in the bed of rivers. In this study, the data obtained from the profiles with Dipole-Dipole and Pole-Pole arrays and geoelectric sounding were interpreted by two-dimensional inversion method in Res2dinv software.The results of the study show that on the upper slope of the road, a small landslide surface is observed at a depth of 4 to 5 meters. This landslide occurred at a small level and has nothing to do with landslides and road gaps, but there is a large-scale landslide potential in the area with landslides at a depth of 30 to 35 meters above the road surface in the future so that groundwater flux accumulation can trigger landslides. Therefore, designing of drainage for engineering structures in this part of the road is essential to prevent road collapse, accidents and possible losses. Moreover, the possibility of landslides in the designs should be considered.