Assessment of cover-collapse sinkholes in SW Sardinia (Italy)

The aim of this article is to show how the application of geophysical techniques at different scales, integrated with hydrogeological and borehole information, can be effective in defining a peculiar hydrogeological context in which cover-collapse sinkholes often occur. The study area lies in SW Sardinia and is characterized by the cropping out of the Palaeozoic basement locally covered by Tertiary–Quaternary sediments. The gravity method,even used alone, proved to be very effective in detecting the regional geological structures to which sinkholes are related, while local details are well defined by means of seimic techniques. The historical analysis of phenomena, the geological knowledge of the area and the results of geophysical surveys allowed to draw 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, to which sinkholes are related