ABSTRACT
The aim of this study was to analyse the mass movement which, in 1959, invaded the Pontesei reservoir (Belluno), drastically reducing its storage capacity. The event was a rotational slide (Varnes, 1978) which mobilised about 4.5 – 5 million mc of debris.
By means of a geologic – technical survey and analysis of the stratigraphies of six borings with continuous sampling drilled in the landslide body, it was possible to hypothesise the presence of colluvial clayey – silty layers inside which a slip surface must have formed. Modelling, carried out using a finite element program, confirmed the efficacy of the geological model of the subsurface as well as the hypothesis of the presence of a very high water table within the slope at the time of the failure. The modelling further demonstrated that the slope would have failed in any case even in the absence of the lake.
