SINKHOLE EVOLUTION IN THE APULIAN KARST OF SOUTHERN ITALY: A CASE STUDY, WITH SOME CONSIDERATIONS on SINKHOLE HAZARD

Sinkhole research gained in recent years wide attention from the Italian scientific community, due to frequent occurrence of sinkholes in several regions of Italy. Among these, Apulia is one of the most important, due to outcropping of soluble rocks in most of the Apulian territory.

Salento, the southernmost part of the region, presents a great variety of sinkhole phenomena, showing different typology, and state of activity; they affect all the cropping out carbonate rocks, from the Cretaceous limestone, representing the local bedrock, to the Oligocene, Miocene, and Plio-Pleistocene calcarenites, up to the middle-upper Pleistocene terraced marine deposits. In many sectors of Salento, sinkholes are so widespread to become the main landform, which especially occur along the low shorelines on both the Adriatic and Ionian seasides.

Analysis of sinkholes, and of their evolution as well, is important not only for understanding the processes at the origin of such events, but also in terms of civil protection issues, that is to reach a knowledge about the possibility to forecast future sinkhole episodes. As an attempt in reaching the two goals above, we present the case study of an interesting sinkhole located a few kilometers north of Lecce. Shape, depth and geomorphological features of the sinkhole pointed out to a multi-phase landform evolution; this was investigated through a multi-integrated approach, from structural geology to geomorphology, and geophyics. Further, the sinkhole has also been analyzed by means of historical documents (aerial photographs, topographic maps, orthophotos) that were useful in reconstructing the recent evolution of the area, even in relation to anthropogenic activities. At this aim, multi-temporal analysis of the available documentation has been performed. Putting together the data from the aforementioned different disciplines, five phases were identified in the evolution of the sinkhole, three of which occurred in the last decades. The case study is suitable to illustrate the likely re-activation of sinkholes, the importance in considering these karst landforms in land management, and the need to carry out detailed dedicated studies aimed at mitigating the related risk.