Pozzuoli’s ground has risen more than five and a half feet since 2005 as the caldera stirs

Ground beneath Pozzuoli’s Rione Terra district now sits about 167.5 centimeters — roughly 5 feet 6 inches — higher than it did when the current uplift cycle began in 2005, according to Italy’s Civil Protection Department. Roughly 30 of those centimeters accumulated since January 2025 alone, a pace that has kept the volcanic system beneath the Phlegraean Fields under a yellow alert for volcanic risk even as officials say they have found no proof that magma itself is rising toward the surface.

That single measurement, taken at the point of maximum deformation in the caldera, has become the clearest way to track a slow-motion crisis that has now outlasted the famous bradyseismic episode of the 1980s in duration, if not yet in damage.

Five and a half feet in two decades, most of it recently

Ground deformation, known locally as bradyseism, has defined the Phlegraean Fields for centuries, but the current episode is unusually well documented. Italy’s Civil Protection Department reports that the uplift which began in 2005 has continued without reversing, and that by the end of July 2026 the cumulative rise at Rione Terra had reached approximately 167.5 centimeters. Roughly 30 of those centimeters were added since January 2025, a period during which the rate of uplift has repeatedly exceeded 30 millimeters a month before easing back toward 20 millimeters a month or less.

A weekly bulletin from the Vesuvius Observatory, issued September 15, 2026, put the most recent pace at about 10 millimeters a month, plus or minus 3 millimeters, measured since early February 2026, and recorded a related 31.5 centimeters of uplift at its own reference station since January 2025. The observatory is run by Italy’s National Institute of Geophysics and Volcanology, known by its Italian acronym INGV, whose Campi Flegrei monitoring program falls under Mauro Antonio Di Vito, director of the Vesuvius Observatory.

The strongest earthquake since the crisis began

Uplift at this scale does not happen quietly. Civil Protection records show earthquake activity climbing alongside the ground deformation since 2018, with the strongest event of the entire episode striking on July 31, 2026 — a magnitude 4.7 quake that hit as part of a seismic swarm in the Phlegraean Fields area. Earlier in the same year, a magnitude 4.4 quake centered offshore in the Gulf of Pozzuoli had already rattled the region. Most of the individual quakes remain minor: about 90% of those recorded in 2023 registered below magnitude 1.0, and the Civil Protection Department says the bulk of the activity clusters at shallow depths of roughly 4 kilometers or less beneath Astroni, the Solfatara-Pisciarelli-Agnano area, Pozzuoli itself, and the Gulf of Pozzuoli.

The pattern has been building for years. Magnitude 4.2 and 4.0 earthquakes struck in September and October 2023, a magnitude 4.4 event followed near Solfatara in May 2024, and two more quakes above magnitude 4 — one onshore, one offshore — struck in May and June 2025. Officials describe the current sequence as comparable in magnitude to the bradyseismic crisis of 1982–84, though the impact on buildings has so far been far smaller, in part because most structures in the area have undergone seismic retrofitting ordered after that earlier crisis.

Italy’s civil-protection alert has held at yellow since 2012

Italy’s National Major Risks Commission has reviewed the Phlegraean Fields situation multiple times since the bradyseismic escalation of September and October 2023, according to the Civil Protection Department, calling in national and international experts to assess whether the uplift and seismicity point toward an eruption. The commission concluded that its findings support the presence of deep-seated magma as the underlying cause of the bradyseismic activity — but without evidence that the magma is actually rising, it recommended keeping the alert at yellow rather than raising it.

The September 15 INGV bulletin reached a similar conclusion for the short term, stating that current monitoring data show no elements suggesting a significant evolution of the situation in the near future. That assessment comes with an explicit caveat: the commission has also directed the Centers of Competence to keep strengthening monitoring and prevention activity in case conditions change enough to justify raising the alert level.

A crisis with less damage than the 1980s, so far

What distinguishes the current episode from the 1982–84 crisis is less the size of the ground movement than the vulnerability of what sits on top of it. Buildings across the municipality of Pozzuoli were evacuated during both the 1970s and 1980s bradyseismic crises, when uplift forced residents out of the historic Rione Terra center. Today, most buildings in the area are three stories or fewer, built or reinforced with concrete and masonry under seismic codes adopted after a March 1981 ministerial decree, referenced in a 2023 emergency decree that classified the area as seismic and tightened construction rules further.

Whether that retrofitting will be enough if the uplift keeps accelerating is the question INGV’s monthly bulletins are built to answer next.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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