There’s Volcanic Unrest At The Campi Flegrei Caldera – Here’s What We Know

Europe’s closest thing to a supervolcano has been stirring for the past 20 years, culminating in a significant spike in seismic activity since the beginning of 2022. Naturally, these developments have got people’s bottoms squeaking, although the likelihood of a full-blown eruption is something scientists are still trying to calculate.

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Known as the Campi Flegrei caldera, the threatening 13-kilometer-wide (8-mile) volcanic field sits beneath a densely populated area in Italy’s Campania region, with towns like Pozzuoli and part of the city of Naples built right on top of it. Unlike your typical cone-shaped mountain volcano, the caldera is made up of a series of sprawling faults spread over a vast area, which means different parts of the field can become active at different times.

The last major eruption occurred in 1538 and significantly reshaped the local landscape while completely burying nearby villages in volcanic debris. This was followed by several centuries of dormancy, only to be broken by multiple periods of renewed activity beginning in the 1950s.

The present unrest began in 2005 and has seen the floor at the center of the caldera rise by 1.4 meters (4.6 feet), mirroring the uplift that was observed prior to the 1538 eruption. However, it’s worth noting that this may reflect the field’s natural “breathing” that occurs even when no such blow-out is forthcoming.

More troubling, however, is the massive rise in seismicity since January 2022, with thousands of tremors detected every month - culminating in a magnitude 4.6 quake on June 30, 2025. To provide a more refined picture of what’s going on underneath this volatile chunk of southern Italy, the authors of a new study used AI to reassess seismic data collected by numerous monitoring stations in the area.

Their findings suggest that a total of 54,319 earthquakes occurred between January 21, 2022, and March 3, 2025 - which is more than four times the 12,083 that had been manually detected by the monitoring stations. As alarming as this sounds, however, the researchers explain that these rumblings do not appear to be portents of an impending disaster.

“Despite the intensifying unrest, we do not observe clear magmatic signatures or evidence of large-scale space-time migration in the recorded seismicity,” they write. In other words, all of the quakes appear to be shallow, with no activity detected below a depth of 3.7 kilometers (2.3 miles).

There’s also no indication of any magma migrating upwards towards the surface, and the ongoing swarm of tremors appears to be associated with an underground hydrothermal system. On top of that, the researchers found that the seismicity is locally constrained, with activity continually occurring in the same fault segments rather than migrating across the caldera.

As for those squeaky Neapolitan bottoms, then, the data would seem to suggest that they can relax, as there’s no indication that the Campi Flegrei caldera is about to erupt.

The study is published in the journal Science.