Earthquakes and volcanoes: how Italy classifies risk

Every square kilometer of Italy sits in one of 4 seismic zones, and 8 volcanoes are under permanent INGV surveillance, which is why the country publishes risk levels rather than reassurance.

Zone 4 is not zone zero

Italian territory is classified into 4 seismic zones by expected peak horizontal ground acceleration with a 10 percent probability of being exceeded in 50 years. Zone 1 runs from 0.25¹g to 0.35¹g, zone 2 from 0.15¹g to 0.25¹g, zone 3 from 0.05¹g to 0.15¹g, and zone 4 up to 0.05¹g.

The important part is that there is no fifth category. Everywhere is classified, so a low number means low hazard rather than none, and building rules follow the number. Before 2003 only 2,965¹ comuni were classified at all, covering 45 percent of the territory and 40 percent of the population.

Who draws the map

The current framework comes from emergency ordinance 3274¹ of 2003, updated by ordinance 3519¹ of 2006, with the detailed classification delegated to the regions inside national criteria. So the zone of a specific comune is a regional act, not a national list you can read in one place.

For a traveler that is mostly invisible and entirely relevant: it is the reason a hotel built after 2003 in the Apennines is built the way it is. It is not a reason to change where you sleep.

8 volcanoes, 3 observatories

INGV's surveillance service monitors 8 Italian volcanoes. Vesuvius, Campi Flegrei and Ischia are watched from the Naples section, the Osservatorio Vesuviano; Etna, Stromboli, Vulcano and Pantelleria from the Catania section, the Osservatorio Etneo; the Colli Albani from the national earthquake observatory in Rome. Palermo runs geochemical surveillance of the Sicilian volcanoes.

That page describes who watches what. It does not classify how active each one is, which is a separate judgment made through the alert scale.

The 4 colors, and who decides them

Green, yellow, orange and red are the 4 levels. Green is the volcano's ordinary activity and the other 3 describe rising departure from equilibrium toward a possible eruption. The levels are set by the civil protection department on assessments from its competence centers, the INGV sections in Catania and Palermo and the University of Florence, in periodic video conferences.

National emergency planning exists for 4 of the 8: Stromboli, Vulcano, Vesuvius and Campi Flegrei. A volcano without a national plan is not a volcano without monitoring.

What a planning zone is, and what it is not

Campi Flegrei is at yellow with an attention phase as of September 2026. Its national plan draws a red zone for preventive evacuation covering around 500,000⁵ residents, all of Pozzuoli, Bacoli, Monte di Procida and Quarto, parts of Giugliano in Campania and Marano di Napoli, and several Naples districts including Soccavo, Pianura, Bagnoli and Fuorigrotta. A yellow zone exposed to ash fall holds over 800,000⁵, across 24 Naples districts and comuni such as Villaricca, Calvizzano, Mugnano, Melito and Casavatore.

Those numbers describe what a plan would have to move, not what is happening. Read them next to the current alert level, never on their own, which is exactly how the civil protection department publishes them. The alert levels page carries the status of each volcano with its check date.

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