Sinkholes are sudden ground collapses with a sub-circular shape, varying in diameter and depth from a few meters to several hundred meters.
Mapping sinkholes and identifying risk areas are crucial for assessing a region’s susceptibility to hydrogeological instability.

The Italian Institute for Environmental Protection and Research (ISPRA) has recorded and studied more than 3,000 cases of natural sinkholes in plains, plateaus, and foothill areas. Detailed field surveys and analyses have been conducted on hundreds of cases.
Currently, over 300 areas susceptible to natural sinkholes have been identified, primarily along the mid-Tyrrhenian side of Italy, particularly in Friuli-Venezia Giulia, Lazio, Puglia, Abruzzo, Campania, and Tuscany.
The Adriatic side, due to its geological and structural features, is less affected by these phenomena, as are the Alps and the Dolomites, except for Friuli-Venezia Giulia and the plateaus of Veneto.

Anthropogenic sinkholes form another category, as they are related to underground cavities created by human activities (anthropogenic sinkholes), primarily for extracting construction materials. Many cities are affected, especially large urban areas built on land that has been historically mined, such as Rome, Naples, Cagliari, Palermo, Reggio Calabria, and Turin. Thousands of cases have also been recorded in smaller and mid-sized towns with extensive underground cavities.
Approximately 4,500 anthropogenic sinkhole events have been documented in Rome, over 800 in Naples, and several hundred in Cagliari and Palermo.

According to the collected data, subsidence affects approximately 18% of Italian municipalities, primarily in Northern Italy, particularly in the Po Valley. In Central and Southern Italy, the phenomenon mainly affects coastal plains. The most affected regions are Veneto and Emilia-Romagna, where over 50% of municipalities experience subsidence.