Slow rock-slope deformation

Giant, deep-seated gravitational slope deformations (DSGSD) affecting entire high-relief valley walls are common in alpine areas, and influence the evolution of mountain landscapes and the related hazards. In the last few years, new characterisation approaches and emerging technology shed new light on the occurrence, distribution, activity, and mechanisms of these spectacular slope failures. This chapter is aimed at providing an overview of alpine DSGSD, as well as a discussion of outstanding issues and future research needs. We review the definition of DSGSD and its typical features, field evidence, settings, and mechanisms. We discuss the distribution and controls on DSGSD occurrence based on the analysis of the first-ever orogen-scale inventory of these phenomena, including over 900 individual phenomena in the European Alps. We demonstrate that DSGSDs are widespread in active orogenic settings and chiefly occur in formerly glaciated areas under significant structural controls, and show that alpine DSGSDs are often active phenomena with a engineering significance. We use the emblematic case study of the Cima di Mandriole sackung to illustrate the complex relations among rock structure, the morpho-climatic evolution of Alpine valleys, and man-made structures, and point out future research needs.