Campi Flegrei: yellow, the second of four levels

The Campi Flegrei are at yellow alert with the operational phase set to attention, fixed by decree on October 30, 2025 and confirmed by the Civil Protection Department on November 4, 2025.

Yellow is a level, not a warning

The Italian national volcanic alert system has 4 levels, green, yellow, orange and red, where green is the volcano's ordinary activity and each step above it marks a growing disequilibrium towards a possible eruption.

Yellow at the Campi Flegrei means a medium disequilibrium and sits at the second step, with the operational phase set to attention, which is phase 2. The level was fixed by decree on October 30, 2025 and confirmed on November 4, 2025 after the volcanic section of the Commissione Grandi Rischi met.

Two facts belong next to each other here. Yellow has been in force since 2012, and in 2025 it was redefined within an update agreed with INGV and the Campania Region. A level in force since 2012 is a state, not an event.

What phase 2 actually obliges anyone to do

Phase 2 carries three duties and all of them are administrative: reinforced monitoring, verification of civil protection operational measures, and non structural prevention through training, information and exercises.

None of those is a restriction on visitors, and none of them is a forecast. If you read that a phase has been activated and expect a road closure, you are reading the wrong kind of document.

The activity a visitor sees in the Solfatara area, in the harbor at Pozzuoli, at Baia and around Lake Averno, is the same activity the instruments have been recording since before the level was set.

Where the current numbers actually live

Monitoring is run by INGV Osservatorio Vesuviano, the Naples section, which publishes 4 products: a monthly surveillance bulletin, a weekly bulletin dedicated to the Campi Flegrei, web bulletins and VONA notices for aviation, all at ov.ingv.it.

That section also watches Vesuvio and Ischia. Nationally, the INGV surveillance service monitors 8 Italian volcanoes: Vesuvio, Campi Flegrei and Ischia from Naples, Etna, Stromboli, Vulcano and Pantelleria from the Catania Osservatorio Etneo, and Colli Albani from the National Earthquake Observatory.

The division of labor is worth understanding before you read a news story. INGV measures; the Civil Protection Department sets the alert level on the advice of competence centers. A page that quotes one without the other is quoting half the system, and this page is a snapshot of September 2, 2026.

A caldera, not a cone

The Campi Flegrei are an active caldera, and they have been for more than 110,000⁷ years. The last eruption was in 1538⁷, when Monte Nuovo was formed, and more than 27 eruptions are counted in the last 5,500⁷ years.

Bradyseism, the slow vertical movement of the ground, produced uplift crises in 1970 to 1972 and in 1982 to 1984, reaching up to around 3.5 meters at Pozzuoli, and a steady new uplift has been under way since 2005, put by the Civil Protection Department at over 150 cm⁷.

Ground deformation is what the instruments watch. It is not an automatic precursor of an eruption, and the distinction is the whole subject. There is more on the mechanism at the ground that breathes.

The zones are evacuation plans, not risk maps

The national plan places around 500,000⁶ residents inside the red zone, the area of preventive evacuation, and over 800,000⁶ inside the yellow zone exposed to ash fall.

The red zone takes in Pozzuoli, Bacoli, Monte di Procida and Quarto in full, parts of Giugliano in Campania and Marano di Napoli, and Naples districts including Soccavo, Pianura, Bagnoli and Fuorigrotta. The yellow zone adds Villaricca, Calvizzano, Mugnano di Napoli, Melito di Napoli and Casavatore, plus 24 districts of Naples.

Those boundaries exist so that an evacuation could be organized. They describe a planning scenario and say nothing about probability, and reading a zone map as a risk map is the commonest error made with this material. For the practical side of a visit see Naples, Vesuvio and volcanoes in Italy.

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