ABSTRACT
This chapter presents the study and stabilization of a paleo-landslide reactivated because of the excavation works carried out at its foot to construct a new lift in Formigal skiing resort. Inclinometers were installed and surface movements were controlled by Global Positioning System techniques in order to analyse the sliding surface and to define the stabilization measures to undertake. After carrying of the stabilization works, an intense control of movements was implemented to observe the behaviour of the landslide and to verify the efficiency of the solution adopted. The slope affected by the landslide is located in the so-called ‘‘Axial Zone’’ of the Central Pyrenees, in north-eastern Spain. A deep valley was dug by the Gallego river after the uplift caused by the last phase of the Alpine orogeny. Due to the high alterability of the shales, a thick layer of weathered material was formed on the slopes, consisting of clays with limestone and slates pebbles.
