Geomorphological Analysis, Rockfall Susceptibility, and Preliminary Hazard Assessment: Case Studies From the Abruzzo Region (Central Italy)

Rockfalls represent a major geological hazard, particularly in tectonically active regions. In this context, assessing rockfall susceptibility and hazard is mandatory for developing proactive measures to safeguard infrastructure and human lives. This study introduces a novel methodology for evaluating the Rockfall (R) and the Earthquake-Induced Rockfall (EIR) susceptibility, followed by a preliminary EIR hazard zonation. Three study areas with distinct physiographic, geological, and geomorphological features were chosen in the Abruzzo region (Central Italy). Selected case studies were investigated following an integrated stepwise approach. Geomorphological field surveys were carried out to identify lithological, geomorphological, and tectonic features, whereas morphometric and geothematic data were derived from high-resolution Digital Terrain Models and available inventories. A GIS-based heuristic approach was followed to assess the R and the EIR susceptibility. Preliminary hazard maps were then generated through 3D rockfall run-out modelling, combining the EIR susceptibility with the expected landslide magnitude. Results show good consistency with field data and fit well within the geomorphological and seismotectonic context. Derived maps depict areas with different instability levels. The highest R susceptibility values are obtained for scarps and steep slopes, the lowest ones in correspondence of flat or gently sloping areas; a general decrease of the EIR susceptibility is also observed moving from the mountainous zones to the coastal ones. Moreover, the run-out modelling pointed out all sectors affected by rockfalls and highlighted other potential rockfall-prone areas. Ultimately, this work represents a prior step for further geomorphological studies focusing on landslide hazard assessment and aimed at proper territorial planning.