18 - Slow rock-slope deformation

Summary

Abstract

Giant, deep-seated gravitational slope deformations (DSGSDs) 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 characterization approaches and emerging technology shed new light on the occurrence, distribution, activity, and mechanisms of these spectacular slope failures. This chapter aims to provide 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 occurrences 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 engineering significance. We use the classic case study of the Cima di Mandriole sackung to illustrate the complex relations between rock structure, the morphoclimatic evolution of alpine valleys, and man-made structures, and suggest future research needs.