The sinkhole of Doganella (Pontina Plain,central Italy)

A case study describes the recent catastrophic subsidence of the land surface neighboring the Lepini karstic range (Lazio region). A number of sinkholes in the Pontina plain are shown on the early topographic maps (dated 1850). Their origin is natural and related to subsidence that occurred during the Holocene. A review of sinkholes in central Italy was made by Facenna and others (1993). The aim of this study is to clarify the possible relationships between tectonics and sinkhole formation. The subsidence phenomena have been related to the slow dissolution of the buried carbonate bedrock due to fluids rich in CO₂, H₂S, and SO₂, which migrate through major tectonic fractures. Lowering of piezometric levels in waterbearing formations and seismic events are also important factors as they may upset the stability of a cave system buried by unconsolidated deposits.