Historical analysis of rainfall-triggered rockfalls: the case study of the disaster of the ancient hydrothermal Sclafani Spa (Madonie Mts, northern-central Sicily, Italy) in 1851

In 1851, the region of Sicily experienced many rainstorm-induced landslides. On 13 March 1851, a rainstorm brought about a severe rockfall disaster near the small town of Sclafani (Madonie Mountains, northern-central Sicily, Italy). Rocks detached from the carbonate crest of Mt Sclafani (813m above sea level) and fell downslope, causing the collapse of the ancient hydrothermal spa (about 430m above sea level) and burying it. Fortunately, there were no injuries or victims. Given its geological, geomorphological and tectonic features, the calcareous–dolomitic and carbonate–siliciclastic relief of Mt Sclafani is extremely prone to landsliding. This study combines the findings of detailed geological and geomorphological field surveys and of a critical review of documentary data. A thorough analysis of documentary sources and historical maps made it possible to identify the location (previously unknown) of the ancient spa. The rockfall dynamics was reconstructed by comparing field reconnaissance data and documentary sources. The 1851 event reconstruction is an example of the application of an integrated methodological approach, which can yield a propaedeutic, yet meaningful picture of a natural disaster, paving the way for further research (e.g. slope failure susceptibility, future land-use planning, protection of thermal springs and mitigation of the impact of similar disasters in this area). Indeed, the intensification of extreme weather events, caused by global warming induced by climate change, has increased the risk of recurrence of a catastrophic event, like that of the ancient Sclafani spa, which is always a potential threat.