Phlegrean Fields, Italy

Location: 40.8N, 14.1E
Elevation: 458 m

Space Shuttle photo 10083795 looking north to Phlegrean Fields and Vesuvius.

Map of the features at Phlegrean Fields caldera from Newhall and Dzurisin (1988). Post-caldera collapse features are the result of volcano-tectonic activity.

The Phlegrean Fields caldera formed about 35,000 years ago with the eruption of 80 cubic km of ash (the Campanian Tuff). The caldera is about 13 km in diameter and includes numerous cones and craters. The caldera is about 25 km west of Vesuvius and 5 km west-southwest of Naples.

Phlegrean Fields (also called Campi Flegrei - "the burning plain") is a caldera with two historic eruptions and signs of unrest in recent years. Between 8050 BC and 1700 BC there were thirteen dated prehistoric eruptions and most were moderate-large to large in size (VEI=3-4). Eight of the prehistoric eruptions produced pyroclastic flows. One of the prehistoric eruptions was phreatic and another produced a dome.

The two historic eruptions were in 1198 and 1538. The 1198 eruption was at Solfatara and small (VEI=1). It caused damage but no fatalities. The 1538 eruption at Monte Nuovo lasted about a week but included several types of activity. This was the first record of a new cone forming on a volcano. The eruption was explosive and generated pyroclastic flows. It also produced a lava lake and lava flows. Near the end of the eruption, while people were climbing on the cone, there was a phreatic explosion. Twenty-four people were killed, some by falling and sliding down the cone. At distances of 5 km, trees were knocked down by the phreatic eruption. About 12 m of uplift preceded the eruption. This observation is based on the presence of borings, made by marine organisms, in marble pillars at the temple of Seraphis. The columns were about 11 m below sea level prior to 1000 AD. Shortly before the eruption started the area near Pozzuoli was uplifted 4 m!

Volcanogenic earthquakes in 1970 caused some houses to collapse. Three people were killed by falling masonry.

1914 postcard of the solfatara at Pozzuoli.

1914 postcard of the solfatara at Pozzuoli.

The most recent episode of unrest began in 1982. Over a two year period, the area near Pozzuoli was uplifted by 1.8 meters and the number and size of earthquakes increased. By mid-1984, the rate of uplift and number of earthquakes declined. Some people were evacuated to protect them from earthquake hazards.

Millions of people live on the Phlegrean Fields caldera and in nearby Naples. Nearly a week will be required to evacuate all the people living near or on Phlegrean Fields caldera.

Campi Flegrei is full of excellent information including a guided excursion.

OASI NATURALISTICA DI MONTE NUOVO has several interesting photos, maps and illustrations (the text is in Italian).

Sources of Information:

Civetta, L. Orsi, G., Pappalardo, L., Fisher, R.V., Heiken, G., and Ort, M., 1997, Geochemical zoning, mingling, eruptive dynamics and depositional processes -- the Campanian Ignimbrite, Campi Flegrei, Italy: J. Volcanol. Geotherm. Research, v. 75, p. 183-219.

Cole, P.D., Scarpati, C., 1993, A facies interpretation of the eruption and emplacement mechanisms of the upper part of the Neapolitan Yellow Tuff, Campi Flegrei, southern Italy. Bull. Volcanology, v. 55, p. 311-326.

Di Vito M., Lirer, L., Mastrolorenzo, G., Rolandi, G., 1987, The 1538 Monte Nuovo eruption (Campi Flegrei, Italy). Bull. Volcanology, v. 49, p. 608-615.

Fisher, R.V., Orsi, G., Ort, M. and Heiken, G., 1993. Mobility of a large-volume pyroclastic flow - emplacement of the Campanian Ignimbrite, Italy. Jour. Volcanol. Geotherm. Res., v. 56, p. 205-220.

Francis, P., 1994, Volcanoes a planetary perspective: Oxford University Press, New York, 443 p.

Lirer, L., Luongo, G., and Scandone, R., 1987, On the volcanological evolution of Campi Flegrei, Italy: EOS, v. 68, p. 226-234.

Mastrolorenzo G., 1994, Averno tuff ring in Campi Flegrei (south Italy): Bull. Volcanology, v. 56, p. 561-572.

Newhall, C.G., and Dzurisin, D., 1988, Historical unrest at large calderas of the world: U.S. Geological Survey Bulletin 1855, 1108 p.

Rosi, M., Santacroce, R., 1984, Volcanic hazard assessment in the Phlegraean Fields: a contribution based on stratigraphic and historical data: Bull. Volcanology, v. 47, p. 359-371.

Rosi, M., Sbrana, A., and Principe. C., 1983, The Phlegrean Fields: structural evolution, volcanic history and eruptive mechanism: Journal of Volcanology and Geothermal Research, v. 17, p. 273-288.

Scarpati, C., Cole, P., Perrote, A., 1993, The Neapolitan Yellow Tuff-A large volume multiphase eruption from Campi Flegrei, Southern Italy: Bull. Volcanology, v. 55, p. 343-356.

Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.

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