ABSTRACT
A major landslide occurred at Agnesberg in the Göta River valley in Sweden in 1993. The consequences of the slide were extensive and the risks involved if the slide had spread were even greater. The slide occured in a river valley with deep deposits of soft, normally consolidated, sensitive clays where landslides are recurrent and where adapted methods of investigations and undrained total stress stability analyses had been developed. Previous investigations in the slide area using these methods had yielded satisfactory safety factors. However, erosion from the water flow and traffic in the river had created locally very steep underwater slopes which were not stable in a long term effective stress perspective. A local slide in such a slope with highly sensitive clay resulted in a series of retrogressive slides. An unobserved local erosion and a method of assessment of the stability conditions which did not take such a chain of events into account thereby resulted in a major slide with a hazard to human safety and very great economic values.
