In Pozzuoli, the earth is never truly still. It rises, falls, and vibrates imperceptibly beneath the feet of those who live overlooking the Gulf. This is the phenomenon of bradyseism, a slow, cyclical deformation of the ground that has marked the history of this city and the Campi Flegrei area for centuries.
The term "bradyseism" derives from the Greek and literally means "slow movement." But behind this seemingly innocuous definition lies a complex geological dynamic, linked to the volcanic nature of the Phlegraean Fields subsurface. The Campi Flegrei area, a vast active caldera, is among the most monitored in the world for its volcanic potential.
A story written in stone
The most obvious symbol of bradyseism is the Macellum of Pozzuoli, historically known as the "Temple of Serapis." Its marble columns tell a story of submersion and resurfacing: the holes left by marine mollusks testify to periods when the ground level was so low that the sea could submerge part of the building.
Over the centuries, Pozzuoli has experienced alternating phases of subsidence and uplift. The period between 1982 and 1984 was particularly intense, when the ground rose almost two meters, forcing thousands of people to leave their homes for safety. More recent events have brought the phenomenon back to the forefront of public attention, with seismic swarms and new measurements indicating a slow but steady rise in the ground.
Why does the earth move?
The bradyseism in the Phlegraean Fields is linked to the pressure exerted by magmatic fluids and gases underground. When the pressure increases, the ground rises; when it decreases, it subsides. This isn't necessarily a prelude to an eruption, but it is a sign of the vitality of the volcanic system.
Experts emphasize that continuous monitoring, through seismic networks, GPS, and geochemical analysis, allows us to monitor the evolution of the phenomenon. The key word remains "prevention": clear scientific information and updated emergency plans are essential tools for living with a dynamic nature.
Living with bradyseism
For the residents of Pozzuoli, bradyseism isn't just a geological phenomenon: it's part of their collective identity. It means checking for cracks in walls, listening with apprehension to news of earthquake swarms, but also developing a resilience rooted in time.
"When the Earth Breathes" isn't just a journalistic metaphor. It's the description of a living, constantly evolving landscape. Understanding bradyseism means understanding the profound relationship between humanity and the environment in one of Europe's most fascinating and complex regions.
Pozzuoli, with its millennia-old history and restless subsoil, continues to remind us that stability is often an illusion and that coexistence with nature begins with knowledge.
A phenomenon that continues to evolve
In recent months the Campi Flegrei They have not "slept": the phenomenon of bradyseism remains active and constantly monitored by national and international scientific institutes.
1. Seismic swarms and recent earthquake activity
- Between February 23 and March 1, 2026, the stations of theNational Institute of Geophysics and Volcanology (INGV) recorded a peak of approximately 70 earthquakes in the Campi Flegrei area, with magnitude up to 3.5 and many tremors concentrated under the Pozzuoli-Agnano area; a sign of continued sustained seismic activity.
- In October 2025 a swarm of over 40 shook It was recorded in a single night, creating apprehension among the population.
- These events are not isolated but are part of a multi-year sequence of micro- and macro-shocks linked to the movements of the caldera.
2. The role of rain in soil deformation
A study of the Geoscience Frontiers published in early 2026 showed that the heavy rains can influence the phenomenon of bradyseism, not only the gases and magmatic fluids in the subsurface. Meteoric water that infiltrates the rock layers can increase the internal pressure, contributing to the ground uplift of areas such as Pozzuoli and the Solfatara.
3. Advanced analytics and AI technologies for monitoring
International researchers are using artificial intelligence models to analyze huge amounts of seismic data and identify swarms and minor events that traditional methods failed to capture. This approach is offering a more detailed view of the faults and movements within the caldera, improving the understanding of bradyseismic dynamics.
4. A recent past marked by notable shocks
In May 2025, a sequence of earthquakes with magnitudes up to 4.4 led the authorities to declare the state of emergency in the Campi Flegrei area, reinforcing attention to the risks associated with living with the phenomenon.
A complex phenomenon, between geology, risk and everyday life
The most recent data confirm that bradyseism is not a static phenomenon: it is dynamic, influenced by geophysical, meteorological and hydrogeological factors, and accompanies the lives of those who live in Pozzuoli and the surrounding municipalities.
What the experts tell us:
- Continuous ground movements – The uplift of the ground continues, although at a variable rate over time, at a rate of a few millimeters per month, according to the most recent geodetic bulletins.
- Recurrent seismic swarms – The occurrence of many small earthquakes is not uncommon in an active volcanic area, but their frequency and the presence of events with a magnitude greater than 3 draw the attention of technical authorities.
- Continuous monitoring – Geochemical (gas, fumaroles) and thermal data accompany the geodetic and seismic analyses, offering a more complete picture of the area's condition.
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The article seems almost objective: it explains the slowness in Pozzuoli and the Phlegraean Fields, but the experts say many things that are not fully understood. Measurements indicate slow rising, seismic swarms are numerous and the population is adapting, but emergency plans are not always up to date and more monitoring and clear information are needed.