Campi Flegrei Is Waking Up. Scientists May Finally Have a Way to Respond

In the shadow of Naples, Italy, sits one of the world’s most dangerous supervolcanoes. Campi Flegrei, known as the Phlegraean Fields, is not a towering mountain like nearby Mount Vesuvius. Instead, it is a sprawling caldera formed from past explosive eruptions. Over the past two decades, signs of unrest have steadily returned. The ground has been lifting, small earthquakes have rattled the region, and gas emissions have been rising. While these signals are cause for concern, two recent studies are changing how experts interpret this activity and offering a potential path forward that could help protect the millions who live nearby.

 

Looking at the Gases: What CO₂ Is Really Telling Us?

 

In 2023, researchers turned their attention to volcanic gas emissions, particularly carbon dioxide. Volcanic CO₂ often spikes when magma starts to move upward, making it a useful indicator of possible eruptions. At Campi Flegrei, emissions in the Solfatara-Pisciarelli zone reached some of the highest levels recorded anywhere, up to 5,000 tons per day.

 

At first glance, such a rise seemed like a clear warning sign. However, the researchers noticed that the mix of gases in the air did not match what would be expected if magma was the only source. By studying ratios of carbon dioxide, nitrogen, and helium, they realized something unexpected. A significant portion of the CO₂ was not coming directly from magma, but from chemical reactions within the surrounding rock.

 

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Heated Rocks and Hidden Sources of Pressure

 

The study revealed that heat and fluids circulating in the hydrothermal system were reacting with calcite-rich rocks, releasing large amounts of CO₂. In fact, between 20 and 40 percent of the gas emissions could be traced back to these non-magmatic sources. This means that high CO₂ levels do not always signal an impending eruption. Instead, they might indicate that the underground system of heated water and steam is becoming more pressurized, which still poses risks, just of a different kind.

 

What a 2025 Study Revealed About Earthquakes and Ground Motion?

 

A second study, published in 2025, explored a broader question: what is really driving the repeated cycles of ground uplift and earthquake activity? Researchers compared patterns from two major unrest episodes, one in the early 1980s and the other from 2011 to 2024. They also created physical simulations of Campi Flegrei’s subsurface, using a setup similar to a moka pot, the traditional stovetop coffee maker.

 

In their model, the lower chamber represented a geothermal reservoir and the upper layer acted as a brittle rock cap. As fluid and steam built up below the cap, pressure increased until the rock fractured, triggering simulated earthquakes. These results led to a crucial insight: the main source of pressure at Campi Flegrei is not magma moving upward, but a sealed geothermal system pushing against the surface.

 

The Mechanics of Pressure Buildup

 

Underneath the town of Pozzuoli lies a pressurized hydrothermal reservoir. The caprock above it behaves in a unique way. It is strong but fibrous and has the ability to self-seal after it cracks. This allows pressure to build again over time. Eventually, the rock gives way, causing ground movement and small earthquakes that residents have learned to live with.

 

Interestingly, the earthquakes tend to start at shallow depths and then migrate deeper. This is the reverse of what typically happens when magma is rising. After each major episode, the land often subsides slightly, which aligns with fluids escaping the system and pressure easing.

 

A New Strategy: Managing the System, Not Just Monitoring It

 

This new understanding brings a surprising possibility. If fluid pressure, not magma, is driving much of the current unrest, then human intervention might help reduce the threat. Unlike magma, which cannot be controlled, the water and steam building up pressure can be influenced through practical steps.

 

Researchers suggest restoring natural water channels to prevent heavy rainfall from infiltrating the system. Monitoring groundwater levels and using controlled wells to relieve pressure could also help. These actions would not eliminate the volcanic threat, but they could lower the chances of sudden, destructive bursts of activity.

 

What This Means for Eruption Risk?

 

Campi Flegrei is still an active supervolcano, and magma remains present at depth. The studies do not suggest that eruption risk has disappeared. What they do indicate is that the type of hazard we may face in the near term could come from steam-driven explosions and intense ground movement rather than lava flows. These events, while not as catastrophic as a full eruption, can still cause significant damage to infrastructure and public safety.

 

The key takeaway is that there may now be an opportunity to move from passive monitoring to active risk reduction. For decades, the focus has been on watching for warning signs and preparing for evacuation. Now, scientists believe we might be able to reduce the risk through water management and engineering.

 

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Living With a Volcano That Breathes

 

Naples and its surrounding towns have lived with Campi Flegrei’s breath for centuries. Cracked roads, sulfuric steam vents, and periodic tremors are part of life there. But with a population of nearly half a million people sitting within reach of the caldera, the stakes are high.

 

These new findings encourage a different kind of preparation. Not only should emergency plans and monitoring systems remain in place, but civil engineering efforts could also play a role in prevention. This includes reinforcing stormwater systems, maintaining historic drainage canals, and using science-based methods to track and manage subsurface pressure.

 

Campi Flegrei remains a powerful and unpredictable force beneath the surface. But for the first time in recent memory, scientists are not just reading its signals. They are beginning to understand the underlying mechanisms  and with that, they are exploring ways to take action before the next big event.

 

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