The Phlegraean Fields, also known as Campi Flegrei in Italian, is a large volcanic caldera located west of Naples, Italy. This area is part of the Campanian volcanic arc, which includes Mount Vesuvius, about 9 kilometers east of Naples. The Phlegraean Fields is monitored by the Vesuvius Observatory. Part of the city of Naples is built over the caldera. The largest known eruptions in the area had a volcanic explosivity index (VEI) of 7. While some media refer to it as a "supervolcano," the scientific term for a supervolcano requires an eruption with a VEI of 8, the highest level on the scale.
The caldera includes 24 craters and volcanic structures. Most of these are located under the Gulf of Naples. The Solfatara crater, which was once thought by ancient Romans to be the home of Vulcan, the god of fire, has steam-emitting fumaroles and boiling mud pools. The area also experiences bradyseismic activity, where the ground level changes over time. Evidence of this is found at the Macellum of Pozzuoli, where marine mollusk marks on marble columns show past sea level changes. Hydrothermal activity, such as hot springs and gas emissions, can still be seen in areas like Lucrino, Agnano, and Pozzuoli.
Today, the Phlegraean Fields includes parts of Naples, such as the districts of Agnano and Fuorigrotta, as well as areas like Pozzuoli, Bacoli, Monte di Procida, Quarto, the Phlegraean Islands, Ischia, Procida, and Vivara. The Solfatara crater was accessible by foot until 2017 and contains over 150 boiling mud pools. Within the caldera, there are several smaller volcanic cones and craters, one of which is filled with Lake Avernus.
Geochemistry
The magma beneath the Phlegraean Fields creates different types of lava. These lavas are usually high in potassium. Trachyte is the most common type of lava produced, and in some cases, it contains unusually high levels of alkali. Other types of lava found include peralkaline phonolitic trachyte and latite. Trachybasalt is also present but is very rare.
Geological phases
Ash found across the Mediterranean region is evidence of a major volcanic eruption that happened 109,000 years ago. This event is known as the Maddaloni Eruption, or X-6. Scientists estimate the eruption's strength as 7.6 on the magnitude scale and a VEI of 7, which is slightly less than the Campanian Ignimbrite eruption that occurred about 40,000 years ago. This makes the Maddaloni Eruption the second-largest event in the eruptive history of the Campi Flegrei area.
Three distinct geological phases or periods have been identified and studied.
Volcanic deposits linked to the eruption have been dated using argon dating to 315,000, 205,000, 157,000, and 18,000 years ago.
In 1538, an eight-day eruption in the area created enough material to form a new hill called Monte Nuovo. Since 1970, this hill has risen about 2 meters (7 feet) above ground level.
The volcanic island of Ischia experienced three damaging earthquakes in 1828, 1881, and 1883. The 1883 earthquake had a magnitude of 4.2–5.2 and caused extreme shaking, rated as XI (Extreme) on the MCS scale. This event led to severe damage on the island and the deaths of more than 2,000 residents.
Between 1982 and 1986, a significant uplift of 1.8 meters occurred, along with many earthquakes.
A 2009 study suggested that changes in the caldera near Pozzuoli could signal an eruption within decades. In 2012, the International Continental Scientific Drilling Program planned to drill 3.5 kilometers (11,000 feet) below the surface near Pompeii to monitor the molten rock chamber beneath and provide early warnings of potential eruptions. Local scientists were concerned that drilling might trigger an eruption or earthquake, but program scientists said it was similar to industrial drilling in the area. Drilling was paused in 2010 but later resumed. A Reuters article noted that the area could produce a "super volcano" that might kill millions, though no evidence supported this claim.
A study by the Istituto Nazionale di Geofisica e Vulcanologia found that volcanic unrest at Campi Flegrei from January 2012 to June 2013 included rapid ground uplift of about 11 centimeters (4 inches), with a peak rate of 3 centimeters (1 inch) per month in December 2012. From 1985 to 2011, ground uplift was mainly linked to the caldera’s hydrothermal system, but this connection changed in 2012. The cause of the uplift shifted to periodic magma movement within a flat, sill-shaped magma reservoir located about 3,000 meters (9,843 feet) deep, 500 meters (1,640 feet) south of Pozzuoli’s port.
In December 2016, volcanic activity increased to the point where an eruption was feared. In May 2017, a study published in Nature Communications by University College London and the Vesuvius Observatory concluded that an eruption might be closer than previously thought. The study noted that volcanic unrest since the 1950s has caused energy to build up in the Earth’s crust, increasing the likelihood of an eruption.
On 21 August 2017, a magnitude 4 earthquake occurred on the western edge of Campi Flegrei. This event caused two deaths and many injuries in Casamicciola, a town on the northern coast of Ischia, which is south of the earthquake’s epicenter.
As of 2023, the reasons for the seismic activity and ground swelling are not fully understood. One model, called the "shallow magma model," suggests magma is pushing upward, which could lead to an explosive eruption. However, seismic imaging does not show a large magma body near the surface. Another model, the "hot fluids model," suggests that steam and hot gases from deeper magma are causing the ground to swell. In this case, activity could stop suddenly or lead to a phreatic eruption, which involves hot liquids, gases, and rock fragments, rather than lava. A phreatic eruption is less dangerous than a magma eruption. Understanding the cause of this activity would improve knowledge about how likely this volcano—and other large volcanoes and supervolcanoes—are to erupt and what signs to watch for.
A February 2020 report noted that ground uplift near Poz
Wine
Italian wine, both red and white, from the Campi Flegrei DOC area is made here. For red wines, grapes used in DOC production must be harvested at a maximum of 12 tonnes per hectare. For white wines, the limit is 13 tonnes per hectare. The finished red wines must have at least 11.5% alcohol, and white wines must have at least 10.5% alcohol. Most Campi Flegrei wines are blends, but single-variety wines can be made if the main grape type makes up at least 90% of the wine. For red single-variety wines, the alcohol must be at least 12%, and for white single-variety wines, at least 11%.
Red Campi Flegrei wines are made with 50–70% Piedirosso grapes, 10–30% Aglianico and/or Sciascinoso grapes, and up to 10% of other local red or white grape varieties. White Campi Flegrei wines are made with 50–70% Falanghina grapes, 10–30% Biancolella and/or Coda di Volpe grapes, and up to 30% of other local white grape varieties.