A Landscape Built to Disappear
The Asiago Plateau, or Altopiano dei Sette Comuni, is a vast limestone block in the Venetian Prealps that is actively dissolving from the inside out. This geological process, known as karstification, has perforated the entire 750-square-kilometer area with an estimated 3,500 sinkholes, called doline, and thousands of underground caves. The plateau is primarily composed of sedimentary rocks, such as Rosso Ammonitico and Biancone limestone, formed between 223 and 35 million years ago when the region was a sea.
The cause of this transformation is rainwater. As rain falls through the atmosphere, it absorbs carbon dioxide, forming a weak carbonic acid. This acid reacts with the calcium carbonate in the limestone, slowly dissolving the rock. Over millions of years, this process has carved an immense subterranean drainage system. As a result, the plateau has almost no surface rivers or streams; water vanishes almost immediately underground, flowing through a network of conduits and caverns. This underground plumbing leads to some of the deepest cave systems in Italy, including the Abisso di Malga Fossetta, which plunges to a depth of 1,011 meters. The northern part of the plateau also shows evidence of glacial activity, which fractured the rock and allowed meltwater to accelerate cave formation.
Living on Unstable Ground
The thousands of sinkholes that pockmark the surface are the most visible evidence of the ongoing geological consumption. These depressions range from small funnels a few meters across to large basins hundreds of meters in diameter. They are direct conduits to the cave systems below. More dramatically, new sinkholes can form without warning through collapse. As underground voids expand, the overlying rock and soil can lose support and suddenly give way.
This process of subsidence is a continuous hazard to the towns and infrastructure built upon the plateau. Monitoring this slow-motion collapse is an active field of research. Scientists use satellite-based InSAR (Interferometric Synthetic Aperture Radar) to detect millimeter-scale ground deformation across the Veneto region, providing data to identify areas at risk. This technology complements ground-based surveys to create detailed maps of ground motion, helping to mitigate risks from a terrain that is constantly, if imperceptibly, changing. Interaction between the complex geology and human activity makes managing water resources and land use a persistent challenge for the region.