Assessment of cover-collapse sinkholes in SW Sardinia (Italy)
Published:January 01, 2007
F. Ardau, R. Balia, M. Bianco, J. De Waele, 2007. "Assessment of cover-collapse sinkholes in SW Sardinia (Italy)", Natural and Anthropogenic Hazards in Karst Areas: Recognition, Analysis and Mitigation, M. Parise, J. Gunn
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The SW part of Sardinia has been afflicted, in recent years, by several cover-collapse sinkholes mostly occurring in low-density population areas. The study area, that lies in the Iglesiente–Sulcis region, is characterized by the cropping out of the Palaeozoic basement related to the South European Hercynian chain, covered with Tertiary–Quaternary sediments. The main rock types that crop out are Palaeozoic metasandstones, metadolostones, metalimestones, shales and metaconglomerates, and Tertiary–Quaternary fluvial–lacustrine continental sediments. The combined application of several geophysical techniques, integrated with boreholes and geotechnical as well as hydrogeological measurements, proved to be very useful and promising in defining in detail the geological context in which each sinkhole has formed. Moreover, the gravity method, even when used alone, proved to be very effective in detecting the regional geological structures to which sinkholes are related.
Eventually, the historical analysis of phenomena, the geological knowledge of the Iglesiente–Sulcis area and the results of properly designed geophysical surveys allows the most probable areas for cover-collapse sinkholes to occur in the future to be determined. In fact, this research pointed out that the depth of the sediment-covered Palaeozoic bedrock is one of the major constraints in delimiting hazardous areas, leading to the construction of a preliminary hazard map. This map shows a belt of high risk, and also suggests the areas in which further geophysical and geotechnical investigations should be carried out to estimate the depth of the bedrock.
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Natural and Anthropogenic Hazards in Karst Areas: Recognition, Analysis and Mitigation
The book presents an overview of the main hazards affecting karst, including collapse and subsidence phenomena, hydrological hazards and human-induced geohazards. Consideration is also given to the problems of geohazard management in karst. The geological and hydrological properties of karst terrains make them among the most fragile in the world and pose serious problems for land managers. Sustainable development in these terrains requires efforts to limit geohazards of anthropogenic origin and to recognize and mitigate against those of natural origin. Aimed at providing the reader with worldwide case studies, the contributions cover a range of geological and morphological settings. Geographically, the fourteen papers discuss very different karst areas, from North America, the Caribbean and Asia to several karst areas in Europe, including the British Isles, Spain, France and Italy.