Extreme rainfall occurred in July 1996 over the Saguenay Region, some 200 km north of Quebec City. With about 1000 land -slides, seven damaged dams, one dike failure, washed out road sections, tens of bridges damaged or destroyed, 1700 properties destroyed or damaged and several casualties, this event was one of the most important natural disasters in Canada. Detailed geotechnical investigations permitted better understanding of the soils involved, mainly sensitive clays and their superficial crust, including their behaviour in landslides, the erosion processes, impacts on infrastructure and sediment deposition.