Electrical imaging of the slip geometry of a deep-seated landslide (Canelles Dam, NE Spain)

Summary The occurrence of large landslides in the slopes of reservoirs may produce a reduction of the water storage capacity and generate water waves which could cause catastrophic flooding if the dam crest is overtopped or breached. The massive and catastrophic rockslide of Vajont reservoir that occurred in 1963 demonstrated the importance of performing detailed geological, geomorphological, hydrogeological and geotechnical investigations in rock masses and soil slopes. Electrical resistivity tomography (ERT) is a non-invasive technology, highly responsive to geological changes that has demonstrated useful to provide the detailed subsurface information required to improve the diagnosis of the slope stability and finding the most suitable zones to fail. The relationships between the electrical resistivity of the high and low-bearing capacity sediments identified in Canelles site highlight the potential of geoelectical methods over other more costly subsurface exploration techniques. The proposed approach show potential to be applied coupled to numerical models to define the boundary conditions up to 100 meters depth with a 5–10 meters resolution and could also help to optimize the required borehole research and monitoring campaign in the initial research stages of landslide characterization.