The Volcano Under Naples Has Been Rumbling for Three Months and Nobody Seems Alarmed

Italy's Campi Flegrei supervolcano has been experiencing elevated seismic activity for three months. Here is what scientists say is happening and what the actual risk level is.

The Campi Flegrei caldera — the supervolcanic system that underlies the Phlegraean Fields west of Naples and beneath parts of the city of Pozzuoli — has been in a state of elevated seismic and ground deformation activity since January 2026. The activity includes daily small-magnitude earthquakes, the majority below magnitude 2.0 and not felt by residents, and continued ground uplift at the rate of approximately 2 centimeters per month — a rate that has been maintained consistently since the current unrest phase began in earnest around 2010.

The Italian National Institute of Geophysics and Volcanology has maintained the Campi Flegrei alert level at Yellow (the second of four alert levels, indicating unrest above background but not imminent eruption) since 2012. The alert level has not changed since January despite the elevated activity, which reflects a careful scientific judgment: the current activity is elevated but within the range of patterns observed during previous phases of unrest that did not culminate in eruption.

Campi Flegrei is a different kind of volcanic hazard from the cone volcanoes — like Etna or Vesuvius — that most people visualize when they think of volcanic eruption. It is a caldera system, meaning the volcanic activity is distributed across a large area rather than concentrated at a single vent. An eruption from Campi Flegrei — which last occurred in 1538 and was a relatively modest event by the system's historical standards — would potentially affect an area inhabited by approximately 800,000 people in high-risk zones and would create ash fall and disruption across a significantly larger area including the city of Naples.

The practical difficulty of managing this risk is well-understood by Italian civil protection authorities and by the scientists who study the system: the geological processes that ultimately lead to eruption are not predictable with the precision that would allow orderly evacuation, while the consequences of unnecessary evacuation of 800,000 people are themselves severe. The monitoring system is state-of-the-art. The scientific understanding is among the most detailed of any volcanic system in the world. The decision framework for action under uncertainty remains the hardest problem.