The Afsarabad landslide represents a significant geological hazard in Iran that remains poorly understood due to limited integrated research. This study employs a multidisciplinary approach combining geological, mineralogical, geotechnical, and geophysical methods to elucidate the complex factors controlling landslide dynamics. Geomorphological and stratigraphic analyses revealed distinct bedrock, colluvium, and marl layers within the slope profile. X-ray diffraction analysis identified substantial quantities of quartz, kaolinite, and montmorillonite, with the highly expandable montmorillonite significantly increasing fracture susceptibility. Geotechnical investigations characterized a 6-meter-thick surface layer of low-plasticity clay (CL) overlying a clay gravel layer (GC) with enhanced drainage properties. Direct shear testing yielded effective cohesion values of 13 kN/m² and 7 kN/m² for the CL and GC layers respectively, with corresponding internal friction angles of 23° and 27°. Finite element stability analysis using Plaxis software revealed critically low safety factors of 0.77 under dry conditions and 0.6 during wet periods, with multiple slip surfaces traversing all lithological units. Geoelectrical surveys employing dipole-dipole arrays confirmed the landslide’s rotational mechanism and delineated sliding surfaces extending 20–30 m in depth. The integrated analysis of these multiple approaches demonstrates that while lithological boundaries do not primarily control failure planes, loose colluvial deposits critically compromise slope stability, particularly under elevated pore water pressure conditions. In conclusion, these findings underscore the necessity of continuous hydrological monitoring and validate the effectiveness of integrated investigative approaches for landslide assessment. The multidisciplinary methodology presented here enhances predictive capabilities for slope failure and provides a robust framework for developing targeted mitigation strategies in landslide-susceptible regions.
Emami et al. (Thu,) studied this question.