Susceptibility assessment of an area subject to a large landslide: the case of San Martino sulla Marrucina (Chieti province - central Italy)

In the San Martino sulla Marrucina territory (Chieti province – central Italy) a large landslide phenomenon (>100 Mm3) is present, causing the collapse of some residential buildings and road networks. The area is geologically very complex. The stratigraphy is characterised by clayey, sandy, conglomerate Upper Pliocene and Lower Pleistocene lithotypes. Quaternary deposits, consisting of alluvial or current terraced soils, grounds and cover detritus, are situated in discordance over the substratum. The hydrogeological system is complex and dislocated. The upper sandy-arenaceous bodies are not very large and do not ensure the persistence of a large water table. The superficial morphology, however, is such as to facilitate the permanency and the infiltration of the waters that saturate the soils within the terraces in counter-slope and the undrained areas, or rapidly seep into the fractures originating in the high zones of the slope. An analysis of the distribution of shapes and processes due to gravity enables us to formulate preliminary hypotheses about the movement in depth. In addition, the aim of this work is to carry out a susceptibility assessment of the zone and to verify the influence of the large landslide on the neighbourhood, utilising a numerical code to study the evolution of the phenomenon.