Gypsum induced landslides in Ollon, Switzerland

This abstract presents a comprehensive case study of landslides in Ollon, Switzerland, emphasizing the complex geological and topographic factors contributing to these geotechnical hazards. Through historical analysis, geotechnical investigations, and geological assessments, the study aims to uncover the underlying causes and mechanisms of the landslides. The study area, situated in the "Bois de la Glaive" region of Ollon, features a challenging terrain characterized by karstified gypsum rock cover, which hinders surface runoff. Steep slopes, coupled with a dense root system, further complicate the stability of the area. Landslides in Ollon involve a debris mass consisting of soil and gypsum blocks, resulting from a complex interplay of geological and environmental factors. Geotechnical analysis involves evaluating slope stability, soil properties, and groundwater conditions. Field investigations and laboratory tests provide crucial insights into shear strength, permeability, and deformation behavior. Geological analysis explores the lithological composition, geological structure, and tectonic history of the region, aiming to understand how geological processes interact with external forces like weathering and erosion. The study also highlights the role of water content in destabilizing the terrain. Rainwater infiltration, especially in the context of gypsum's impermeability, plays a significant role in slope instability.