The main goal of this study is to describe the spatial and temporal evolution of rock fall phenomena triggered by rapid slope deformation. To this end, we combine low cost seismic sensors and image processing to study a large instability adjacent to the Great Aletsch glacier in the Swiss Alps, i.e. the Moosfluh slope, which is undergoing an acceleration phase since the late summer 2016. With this analysis, we aim at a better understanding of the relationship between the kinematic behavior of rock slope instabilities and progressive rock mass damage, which may lead to catastrophic failure.
The Great Aletsch Region is a prominent site located in Switzerland, hosting the largest glacier of European Alps. In this area, glaciers have undergone to several cycles of advancement and retreat, which have deeply affected the geomorphological evolution of the surroundings (Grämiger et al. 2017). The glacier is experiencing a progressive retreat in the order of 50 meters every year, consequently, load is released from the adjacent rocks previously constrained by the ice mass, and slope instabilities might be triggered (e.g., Cossart et al. 2008). In the Aletsch region, a deep-seated slope instability called Moosfluh shows since the 90's a slow but progressive increase of surface displacement (Strozzi et al. 2010). The moving mass associated to Moosfluh affects an area of about 2 km2 and entails an estimated volume of about 150–200 Mm3 (Kos et al. 2016). In the late summer 2016, an unusual acceleration of the Moosfluh rockslide was observed.