Naples Underground Geothermal Zone

High Quality Content by WIKIPEDIA articles! Running beneath the Italian city of Naples and the surrounding area is an underground geothermal zone called the "Campi Flegrei" ("fiery fields"). This geothermal area runs generally from Mount Vesuvius beneath a wide area including Pompei, Herculaneum, Naples and over to Pozzuoli and the coastal Baia area. Mining and various infrastructure projects during several millennia have formed extensive caves and underground structures in the zone. Over millennia, extreme geothermal pressure has helped form a strong, durable tuffaceous volcanic sandstone called tuff, a rock composed of compressed and compacted volcanic ash ejected during a volcanic eruption. The entire Naples area is a geothermal region with deep veins of the tuff sandstone, generically referred to as "yellow tuff". It runs in deep veins beneath Naples and the area around it in strata which are found at different depths.