Landslides of the flow-type are frequently triggered by rainfall as shallow landslides in different types of soils and geo-environmental contexts. When involving open slopes, these landslides often occur in triangular source areas where initial slides turn into avalanches through further failures and/or eventual soil entrainment. Similar phenomena are frequently observed in layered snow depos its and they are also recognised in ashy deposits on Mars. Significant examples are systematically recorded in Southern Italy where pyroclastic deposits overlie carbonate massifs. Particularly, in May 1998, rainfall triggered
many destructive triangular shallow landslides of the flow-type along the slopes of Pizzo d’Alvano massif (Sarno-Quindici event). The available data-set allowed their failure and post-failure stages to be modelled. Numerical analyses were performed using limit equilibrium as well as hydro-mechanical coupled and uncoupled stress-strain approaches. The obtained results are discussed in the paper, providing a preliminary framework for this type of slope instability phenomena that is poorly addressed in the current literature.