Residents across Naples were jolted awake in the early hours of Friday, July 31, after a magnitude 4.7 earthquake struck the densely populated metropolitan area at 9:14 a.m. local time.
The epicentre was located near the town of Pozzuoli, west of Naples, within the volcanic region known as Campi Flegrei (Phlegraean Fields).
The earthquake injured at least 21 people, according to Italian authorities, while several buildings suffered structural damage.
Falling masonry, cracked walls and collapsed chimneys were reported in parts of Pozzuoli and western Naples, prompting emergency inspections of schools, residential buildings and public infrastructure.
Train services were temporarily disrupted as engineers assessed railway lines, while thousands of residents gathered outdoors as a precaution. At the time of writing, officials continue to evaluate the full extent of the damage.
For many people, an earthquake near Naples immediately brings one volcano to mind.
Mount Vesuvius.
Scientists, however, are paying even closer attention to another volcano – one that is far less famous but potentially even more complex.
The Earthquake Was Not Caused by Vesuvius
Although Vesuvius dominates the skyline of Naples and remains one of the world’s most famous volcanoes, the latest earthquake originated beneath Campi Flegrei, a vast volcanic caldera stretching roughly 12-15 kilometres across western Naples and the Bay of Pozzuoli.
Unlike Vesuvius, which is a classic cone-shaped volcano, Campi Flegrei is the remnant of an enormous ancient eruption that collapsed in on itself thousands of years ago.
Today, the caldera lies beneath towns, suburbs, roads, ports and parts of the city of Naples itself, making it one of the most densely populated volcanic regions anywhere on Earth.
Rather than being triggered primarily by movement along major tectonic faults, many of the earthquakes recorded here are linked to volcanic processes occurring several kilometres beneath the surface.
A Volcano That Makes the Ground Rise and Fall
One of Campi Flegrei’s most remarkable characteristics is a phenomenon known as bradyseism.
Instead of remaining stable, the ground slowly rises and sinks over periods of months or years as magma and volcanic gases move beneath the caldera.
These gradual movements place enormous stress on the surrounding rocks.
Eventually, that pressure is released through hundreds – or sometimes thousands – of small earthquakes.
Over the past several years, scientists have observed a noticeable increase in both ground uplift and seismic activity across the region.
While this does not necessarily mean that an eruption is imminent, it explains why every significant earthquake around Naples receives close attention from volcanologists.
Why Campi Flegrei Worries Scientists More Than Vesuvius
This may surprise many visitors. When tourists arrive in Naples, most head straight for Mount Vesuvius or the ruins of Pompeii.
Yet many volcanologists consider Campi Flegrei the more challenging volcanic system to monitor. The reason is simple.
Vesuvius is a single volcanic cone whose behaviour is relatively well understood. Campi Flegrei is an enormous caldera containing dozens of volcanic vents spread across a wide urban area.
Its underground plumbing system is far more complex, making it difficult to predict exactly how periods of unrest may evolve.
Scientists therefore monitor the area continuously using satellite observations, GPS stations, seismic sensors and gas-emission measurements.
Their goal is not to predict earthquakes precisely – something that remains impossible – but to detect any significant changes that might indicate evolving volcanic activity.
Which Areas Were Affected?
The strongest shaking was reported in Pozzuoli, Bacoli, Bagnoli, Fuorigrotta and western districts of Naples.
The earthquake was also felt across much of the Campania region, including parts of the Amalfi Coast, although no significant damage has been reported there.
For the millions of visitors who travel each year to Naples, Pompeii, Capri and the Amalfi Coast, the latest earthquake serves as a reminder that these iconic destinations are part of one of Europe’s most active geological landscapes.
A Region That Has Been Shaking for Decades
Earthquakes around Campi Flegrei are nothing new. During the major bradyseismic crisis between 1982 and 1984, the ground beneath Pozzuoli rose by nearly two metres.
Thousands of earthquakes were recorded, forcing the evacuation of more than 40,000 residents from the town’s historic centre.
Although no major eruption followed, the crisis transformed how Italy monitors volcanic hazards. Since then, Campi Flegrei has remained under constant scientific observation.
In recent years, seismic activity has intensified once again, with frequent earthquake swarms, accelerating ground uplift and increasing volcanic gas emissions drawing renewed attention from researchers worldwide.
Living With a Restless Landscape
Naples has always lived alongside powerful geological forces. The eruption of Mount Vesuvius in AD 79 buried Pompeii and Herculaneum beneath volcanic ash, preserving them for nearly two millennia.
Campi Flegrei tells a different story. Its hazards unfold more slowly, often through years of subtle ground deformation punctuated by recurring earthquakes.
For local residents, occasional tremors have become an accepted part of daily life. For scientists, however, each new earthquake provides another valuable piece of data helping them understand how one of Europe’s most complex volcanic systems is evolving.
Nature Beneath One of Europe’s Most Beautiful Coastlines
Millions of people visit the Bay of Naples every year for its spectacular scenery, ancient history and world-famous cuisine.
Few realise that beneath this remarkable landscape lies one of the most closely monitored volcanic regions on the planet.
Friday’s earthquake is a reminder that the same geological forces that created the Bay of Naples continue to shape it today.
The Earth beneath southern Italy is very much alive – and scientists are watching it more closely than almost anywhere else in Europe.
Sources:
- Reuters – Coverage of the July 31, 2026 Naples earthquake and emergency response.
- Italian National Institute of Geophysics and Volcanology (INGV) – Earthquake bulletins and Campi Flegrei monitoring.
- Italian Civil Protection Department – Official updates on damage assessments and emergency measures.
- United States Geological Survey (USGS) – Earthquake science and tectonic setting of southern Italy.
- Smithsonian Institution – Global Volcanism Program: Campi Flegrei and Mount Vesuvius.
- Encyclopaedia Britannica – Campi Flegrei, Mount Vesuvius and the geology of the Bay of Naples.
- European Geosciences Union (EGU) – Research on bradyseism and volcanic unrest in Campi Flegrei.
