SLOPE INSTABILITY PROCESSES AFFECTING THE PIETRA DI BISMANTOVA GEOSITE (NORTHERN APENNINES, ITALY)

The Pietra di Bismantova, a vast biocalcarenite slab, is an impressive landmark and a unique feature in the gentle hilly landscape of the Reggio Emilia Apennines, Italy. It consists of a stratified calcareous rock type, rich in molluscs and other fossilised remains typical of a tropical climate. The site also has significant historical and cultural interests, including remains from Bronze Age and early Iron Age settlements. The perpendicular rock faces of the Pietra di Bismantova have for many years attracted rock climbers and hikers. Furthermore, the sheer calcareous walls are favoured sites for endemic plants and nesting of rare birds. Since the end of the last glaciation, the site has been subject to intense degradational processes affecting the rock slopes. Today, these pose serious problems for its conservation and the safety of visitors. The southern part is mainly affected by occasional rockfalls of varying magnitude. In contrast, the north-eastern part is much more jointed and dismembered and is subdivided into several loose blocks subject to slope movements with a complex style of activity. The results of a geomechanical and geomorphological survey are used to identify the area most prone to geomorphological hazards, particularly rockfalls. They show that the areas potentially most subject to landslides are the SE, NE and NW faces, where the rock parameters are poorest and degradational processes are particularly intense. Numerical modelling of rockfall phenomena indicates that the hazards are particularly high along the SE and W faces, where footpaths and climbing tracks are also located. Remedial measures should be introduced in these critical areas to stabilise the cliff and guarantee safe access for the numerous visitors to this geosite.