Is Campi Flegrei About to Erupt?

The Short Answer

Campi Flegrei, the vast volcanic caldera immediately west of Naples, is not confirmed to be on the verge of eruption — but a 2026 study confirmed that fresh magma is arriving at depth beneath the system, and the ground has already risen more than 1.4 metres since 2005, making it one of the most closely watched volcanic systems on Earth.

What Is Campi Flegrei?

Campi Flegrei — Latin for “burning fields” — is a supervolcanic caldera roughly 13 kilometres across, sitting partly beneath the Bay of Pozzuoli west of Naples. It is the largest active caldera in Europe. Unlike a classic cone volcano, Campi Flegrei is a collapsed crater system so wide that roughly half a million people live entirely within its rim, most of them unaware they are residents of an active volcano.

The caldera was formed by two cataclysmic eruptions: one around 39,000 years ago and another approximately 15,000 years ago. The earlier event was so violent it spread ash across Europe and is thought to have contributed to the final extinction of the Neanderthals by collapsing ecosystems already under pressure.

What Do the Roman Columns Tell Us?

At the ancient market of Pozzuoli, a set of Roman marble columns bears one of geology’s most striking pieces of evidence. Marine mollusc borings — the feeding marks of a species that lives underwater — appear roughly seven metres above the current ground level. This means the ground silently sank below the sea after the columns were built, remained submerged long enough for molluscs to colonise the stone, and then rose again. All of this happened within recorded history, without a single eruption.

This vertical movement, called bradyseism, is a defining feature of Campi Flegrei. The ground rises and falls across decades and centuries driven by pressure changes in the hydrothermal and magmatic system below.

The 1982 Crisis and What It Revealed

In 1982 and 1983, Campi Flegrei entered a dramatic unrest phase. The ground near Pozzuoli rose by 1.8 metres in less than two years. More than 16,000 earthquakes shook the region. Forty thousand residents were evacuated from Pozzuoli in one of the largest peacetime evacuations in Italian history. The volcano never erupted. That episode revealed how severely a caldera system can disrupt human life without ever breaking the surface.

What Is Happening Now?

Since 2005, Campi Flegrei has been in a sustained episode of ground uplift. By the mid-2020s, the cumulative rise had exceeded 1.4 metres — approaching the scale of the 1982 crisis. Earthquake swarms have become more frequent, and gas venting at the surface has intensified in certain zones.

Then, in 2026, researchers published findings confirming that fresh magma has been intruding at depth beneath the caldera. This is a significant escalation in scientific understanding. Previous unrest episodes could be explained largely by hydrothermal fluids — superheated water and gas — shifting within the crust. The presence of new magmatic material changes the monitoring picture substantially and has prompted calls for updated emergency planning across the region.

How Dangerous Is It?

Italian civil protection authorities maintain a colour-coded alert system for Campi Flegrei. The system has been at elevated alert for years. A full-scale eruption would threaten not just the half million people living inside the caldera but the three million residents of greater Naples nearby. Evacuation of that population in a crisis scenario is one of the most complex emergency management problems in Europe.

Scientists are careful to note that unrest does not equal eruption. Campi Flegrei may continue in its current state for years or decades without an eruptive event. But the confirmation of fresh magma at depth means the system can no longer be treated as purely hydrothermal in nature. The last time Campi Flegrei actually erupted was in 1538, when Monte Nuovo — an entirely new hill — was built in approximately one week. Nobody alive has seen this caldera erupt. That fact alone makes it one of the most consequential unknowns in European geology.