Urban sinkholes and implications in coastal cliff retreat

Abstract

The development of collapse sinkholes in urbanized coastal areas represents a serious threat to the safety of infrastructures and human settlements. Although this phenomenon is linked to natural coastal evolution processes, it poses a significant risk in densely urbanized settings. This study investigates two sinkholes that developed along the eastern coast of Sicily (Italy), in different geological settings. One occurs within a carbonate rock mass affected by karst processes and tectonics, whereas the other formed in a volcanic environment prone to intense fracturing and marked heterogeneity of the lava rocks. Aerial photogrammetric surveys were conducted to perform a digital rock mass analysis aimed at identifying the main discontinuities controlling the formation of these structures. The results highlight how lithological and structural differences govern sinkhole development, providing valuable insights for risk assessment and management of critical coastal areas.