Landslide phenomena in weathered granitoid rocks of the Fabrizia surroundings (Serre Massif, southern Italy)

Abstract

This work shows the preliminary data on the weathered granitoids and related landslide phenomena in the area surrounding Fabrizia, Serre Massif (southern Calabria). Fabrizia lies on an old erosion surface composed of basement rocks made up of weathered granitoids, in turn belonging to the Serre Massif granitoid complex, and overlain by thin eluvial-colluvial deposits. The weathered profiles of the granitoid complex have been studied through a visual description, following both qualitative and quantitative criteria. Weathered profiles are mainly composed by rocky masses varying from completely weathered to highly or moderately weathered terms, characterized by Schmidt Hammer values ranging from 0-20 (class V) to 21-43 (class IV-III). The slopes of the Fabrizia surroundings are characterized by widespread mass movements. Typical landslide typologies are rockfalls for the fresher rocks (class III) and translational slides for the more weathered rocks (classes IV and V). The shallow horizons composed both by thin eluvial-colluvial deposits and by more weathered granitoids (class V-VI), may generate dangerous earth flows, debris flow or debris avalanches under intense and extensive rainfalls.