Towards the definition of slope instability behaviour in the Alvera mudslide (Cortina d'Ampezzo, Italy)

The purpose of this paper is to describe the investigations carried out on a mudslide in the area of Cortina d'Ampezzo (Dolomites, Italy) in the framework of the TESLEC Project (the temporal stability and activity of landslides in Europe with respect to climatic change) supported by the Environment and Climate Programme of the European Union (contract no. EV5V-CT94-0454). After a brief geological and geomorphological description, the results of geotechnical investigations are presented. Several boreholes were drilled and equipped with inclinometer tubes, electric piezometers and extensiometer devices. The analysis of the rock cores allowed the identification of a main slip surface ranging from a depth of 18 to 25 m. Inclinometer measurements show a rate of movement of some centimetres per year. Another more superficial slip surface which appears very active was also identified at a depth of 5 m in the lower sector of the landslide. A detailed topographic survey was also carried out for measuring planimetric displacements and for the elaboration of a new reliable contour map and a high-detail section across the mudslide longitudinal axis. On the basis of collected data, a dynamic stability model was developed in order to determine the relationships between piezometric fluctuations and velocity variations. The model was first applied to the most superficial landslide which, owing to its geometrical characteristics, may be considered as an infinite slope. (C) 1999 Elsevier Science B.V. All rights reserved.