Why the ground rises
Pressure from fluids, gas and deeper volcanic processes can deform the rocks above the caldera and lift the surface around Pozzuoli.
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View latest status →Naples · A restless caldera beneath a living city
Campi Flegrei
A wide volcanic system where earthquakes, ground uplift and gas emissions reveal a caldera that has never truly gone quiet.
Scroll beneath the caldera ↓
Chapter one
A volcano without one summit
Campi Flegrei is not a single cone. It is a broad, partly submerged caldera west of Naples, filled with towns, bays, lakes, vents and the remains of many past eruptions.
The volcanic field covers roughly 130 square kilometres, including a substantial offshore portion. Its landscape contains more than two dozen eruptive centres — maars, tuff rings, cones and domes — rather than one permanent central vent. Solfatara, Pisciarelli, Agnano, Astroni, Lake Averno and Monte Nuovo are all pieces of the same larger system.
That geography matters. A future eruption would not necessarily begin where the last one occurred, and scientists cannot simply watch a single crater. Monitoring networks therefore track deformation, earthquakes, gas chemistry, temperature and gravity across the caldera.
~130 km²Approximate caldera area
458 mMaximum elevation · Camaldoli
1538Last eruption · Monte Nuovo
INGV-OVOfficial monitoring body
Quick factsCampi Flegrei at a glance
- Type
- Nested caldera and monogenic vents
- Location
- Naples–Pozzuoli, Campania
- Monitoring focus
- Bradyseism, earthquakes, gas and deformation
- Last eruption
- Monte Nuovo · 1538
- Characteristic activity
- Bradyseism, shallow earthquakes and hydrothermal gas
- Observatory
- INGV · Osservatorio Vesuviano
The landscape
A caldera occupied by sea and city
Pozzuoli and the western districts of Naples sit inside or along the margins of the volcanic system.
The modern coastline is not fixed. Ancient Roman structures at Pozzuoli record repeated rises and falls of the land, while submerged and uplifted archaeological remains preserve centuries of bradyseismic movement. This long history explains why ground deformation is both scientifically important and culturally visible.
Campi Flegrei’s density of population makes risk fundamentally different from that at a remote volcano. Even moderate earthquakes can affect vulnerable buildings, while any future eruptive crisis would require decisions across a complex urban region.
LocationWest of Naples, Campania, Italy
Volcano typeCaldera and monogenic vents
Main active areasPozzuoli · Solfatara · Pisciarelli
Prevailing activityHydrothermal emissions, uplift and seismicity
Monitoring authorityINGV · Osservatorio Vesuviano
Last eruptionMonte Nuovo · 1538
Chapter two · The ground breathes
Bradyseism is the story of Campi Flegrei
The land around Pozzuoli repeatedly rises and falls as pressure changes beneath the caldera. It is a measurable process — not an eruption countdown.
Why earthquakes follow
As stress changes, shallow rocks fracture. Swarms can be strongly felt, but their meaning depends on depth, location, energy and the wider monitoring picture.
Why uplift is not a countdown
Bradyseism records changing pressure. It does not provide an eruption date, and unrest can continue for years without magma reaching the surface.
Chapter three · Reading the signals
How scientists interpret a restless caldera
No individual earthquake, gas reading or uplift measurement can diagnose what happens next. INGV evaluates how multiple signals change together through time.
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This profile explains the science behind Campi Flegrei. For the latest alert level and operational guidance, use the Volcoholics status directory and follow INGV-OV and Italian Civil Protection.
View latest status →BradyseismGround movementUplift and subsidence are measured around Pozzuoli
SeismicityRock responseDepth, location and energy reveal how stress changes
Gas emissionsFluid chemistrySolfatara and Pisciarelli are key survey areas
Thermal activityHeat transferField and remote observations track temperature change
Chapter four · Continuous observation
Watching the whole caldera, not one crater
INGV’s Vesuvius Observatory combines dense ground networks with satellite observations and repeated field measurements. The goal is to identify meaningful change across the caldera rather than react to one isolated signal.
Seismic networkLocates earthquakes and follows swarm migration, depth and energy release.
GNSS and tiltMeasures uplift, subsidence and shorter-term deformation across the urban area.
Gas and thermal surveysTracks CO₂ flux, fumarole chemistry and temperature at hydrothermal zones.
InSAR and fieldworkAdds regional deformation context and checks remote observations on the ground.
Diagram is illustrative; station symbols show monitoring methods and key areas, not every instrument location.
Eruptive history
Forty thousand years of volcanic change
~40,000 years
Campanian Ignimbrite
The largest known eruption in the system’s history generated widespread pyroclastic currents and deposits across much of Campania.
~15,000 years
Neapolitan Yellow Tuff
Another major caldera-forming eruption reshaped the volcanic field and produced extensive yellow-tuff deposits used throughout Naples.
Recent millennia
Many smaller vents
Activity formed craters, maars, tuff rings and cones at different locations within the caldera.
1538
Monte Nuovo
The only eruption in historical times began on 29 September after intense earthquakes and dramatic coastal uplift, building a new cone in only days.
1982–84
The modern uplift crisis
Rapid uplift and intense seismicity forced evacuations in Pozzuoli and became a defining episode in modern Campi Flegrei monitoring and planning.
21st century
Renewed bradyseismic activity
Episodes of uplift, seismic swarms and hydrothermal change have driven major expansion of monitoring and civil-protection planning.
The main hazards
Living with unrest beneath a dense urban area
Risk is not limited to a future eruption. Earthquakes, deformation and gas can create serious local impacts during prolonged periods of unrest.
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Shallow earthquakes
Strongly felt events can damage vulnerable buildings and repeatedly disrupt daily life even without an eruption.
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Ground deformation
Uplift and repeated movement can strain roads, ports, utilities, buildings and underground infrastructure.
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Volcanic gases
CO₂ can collect in low or enclosed spaces, while fumarolic areas present direct local hazards.
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Ash and eruptive hazards
A future explosive eruption could bring ashfall and dangerous pyroclastic currents, with impacts shaped by vent location and wind.
Myths separated from monitoring
What Campi Flegrei’s unrest does — and does not — mean
“Every earthquake means magma is rising.”
Shallow earthquakes can result from changing stress and hydrothermal processes. Scientists interpret their location, depth and evolution alongside deformation and gas data.
“Uplift guarantees an eruption.”
Uplift confirms pressurisation and unrest, but similar crises have occurred without eruption. It is evidence to assess, not a countdown clock.
“Any unrest means Naples will be destroyed.”
Preparedness covers a range of credible scenarios. Unrest alone does not establish the timing, location or scale of a future eruption.
“Campi Flegrei is overdue.”
Volcanoes do not erupt on fixed schedules. Past intervals cannot be used to calculate a deadline for the next event.
Volcoholics Insight
Restless does not mean erupting
Campi Flegrei demonstrates why volcanic unrest must be interpreted through the full multiparameter picture. Earthquakes, uplift and gas changes are important evidence, but no single signal can provide an eruption date. The responsible approach is to follow INGV science and the operational guidance of Italian Civil Protection.
Frequently asked questions
Campi Flegrei questions answered
Where can I find the latest Campi Flegrei status?
Use the Volcoholics volcano-status directory for the latest verified summary, then follow INGV’s Vesuvius Observatory and Italian Civil Protection for official scientific and operational updates.
What is bradyseism?
Bradyseism is slow ground uplift or subsidence associated with pressure changes beneath a caldera. At Campi Flegrei it is closely linked with shallow seismicity and hydrothermal processes.
Does uplift mean an eruption is imminent?
No. Uplift confirms changing pressure beneath the caldera, but similar episodes have occurred without eruption. Scientists interpret deformation alongside earthquakes, gas chemistry, temperature and other measurements.
Is Campi Flegrei a supervolcano?
The term is informal and often sensationalised. Campi Flegrei has produced very large caldera-forming eruptions, but many of its eruptions were much smaller. A future eruption would not automatically repeat the largest event.
Could it erupt like the Campanian Ignimbrite again?
Very large eruptions are part of its geological history, but past scale alone cannot predict the next event. Monitoring and planning consider a range of credible scenarios rather than assuming the most extreme outcome.
Who should residents follow?
INGV’s Vesuvius Observatory provides scientific monitoring, while the Italian Civil Protection Department and local authorities provide operational guidance and emergency information.
Official sources
Built from the agencies watching the caldera
This profile prioritises INGV, the Vesuvius Observatory and the Italian Civil Protection Department. Stable geological context is cross-checked against official INGV resources and peer-reviewed research.