Phlegraean Fields. The Phlegraean Fields is a large supervolcano situated to the west of Naples, Italy. It was declared a regional park in 2003. The area of the caldera consists of 24 craters and volcanic edifices; most of them lie under water. Hydrothermal activity can be observed at Lucrino, Agnano and the town of Pozzuoli. There are also effusive gaseous manifestations in the Solfatara crater, the mythological home of the Roman god of fire, Vulcan. This area is monitored by the Vesuvius Observatory. The area also features bradyseismic phenomena, which are most evident at the Macellum of Pozzuoli: bands of boreholes left by marine molluscs on marble columns show that the level of the site in relation to sea level has varied. Three geological phases or periods are recognised and distinguished. The First Phlegraean Period. It is thought that the eruption of the Archiflegreo volcano occurred about 39,280±110 years ago, erupting about 200 km 3 of magma to produce the Campanian Ignimbrite eruption. Its Volcanic Explosivity Index was 7. The dating of the Campanian Ignimbrite Eruption to ~37,000 calendar years B.P. draws attention to the coincidence of this volcanic catastrophe and the suite of coeval, Late Pleistocene biocultural changes that occurred within and outside the Mediterranean region. These included the Middle to Upper Paleolithic cultural transition and the replacement of Neanderthal populations by anatomically modern Homo sapiens, a subject of sustained debate. No less than 150 km 3 of magma were extruded in this eruption, traces of which can be detected in Greenland ice cores. As widespread discontinuities in archaeological sequences are observed at or after this eruption, a significant interference with ongoing human processes in Mediterranean Europe is hypothesized. It is possible that these eruptions drove Neanderthals to extinction and cleared the way for modern humans to thrive in Europe and Asia. The area is characterised by banks of piperno and pipernoid grey tuff at Camaldoli hill, as in the northern and western ridge of Mount Cumae; other referable deep products are those found at Monte di Procida, recognizable in the cliffs of its coast. The Second Phlegraean Period, between 35,000-10,500 years ago. This is characterized by the Neapolitan yellow tuff that is the remains of an immense underwater volcano, with a diameter of c.; Pozzuoli is at its center. Approximately 12,000 years ago the last major eruption occurred, forming a smaller caldera inside the main caldera, with its centre where the town of Pozzuoli lies today. The Third Phlegraean Period, between 8,000-500 years ago. This is characterized by white pozzolana, the material that forms the majority of volcanos in the Fields. Broadly speaking, it can be said there was an initial activity to the southwest in the zone of Bacoli and Baiae; an intermediate activity in an area centred between Pozzuoli, Spaccata Mountain and Agnano; and a more recent activity towards the west, which formed Lake Avernus and Monte Nuovo. Volcanic deposits indicative of eruption have been dated by argon at 315,000, 205,000, 157,000 and 18,000 years ago. The caldera, which now is essentially at ground level, is accessible on foot. It contains many fumaroles, from which steam can be seen issuing, and over 150 pools of boiling mud. Several subsidiary cones and tuff craters lie within the caldera. One of these craters is filled by Lake Avernus. In 1538, an eight-day eruption in the area deposited enough material to create a new hill, Monte Nuovo. It has risen about 2 m from ground level since 1970. At present, the Phlegraean Fields area comprises the Naples districts of Agnano and Fuorigrotta, the area of Pozzuoli, Bacoli, Monte di Procida, Quarto, the Phlegrean Islands. A 2009 journal article stated that inflation of the caldera centre near Pozzuoli might presage an eruptive event within decades. In 2012 the International Continental Scientific Drilling Program planned to drill 3.5 km below the earth's surface near Pompeii, in order to monitor the massive molten rock chamber below and provide early warning of any eruption. Local scientists are worried that such drilling could itself initiate an eruption or earthquake. In 2010 the Naples city council halted the drilling project. Programme scientists said the drilling was no different from industrial drilling in the area. The newly elected mayor allowed the project to go forward. A Reuters article emphasized that the area could produce a super volcano that might kill millions.