Evaporite karst and sinkholes: a synthesis on the case of Camaiore (Italy)

In 1995 a sinkhole suddenly formed at Camaiore (Tuscany, Italy), causing destruction or heavy damages to several houses and resulting in the evacuation of many people. To understand the causes, for the formation and evolution of the collapse, surface and underground geologic features were investigated and reconstructed on the basis of geologic and geognostic surveys. The sinkhole area is underlain by thick alluvial deposits that cover a bedrock consisting of the Calcare cavernoso formation. This formation results from hydration and dissolution of Triassic evaporites and has a characteristic spongy and vacuolate texture. The bedrock contains karst cavities, generally filled by breccia and/or alluvial materials. Thus, the sinkhole disaster could be ascribed to deep collapse of a cave in the bedrock, and might be considered a distant effect of ancient karst phenomena in evaporites.