Experts have warned that hundreds of thousands of people are at risk from a supervolcano that is starting to wake up in Italy.
Over the last few months a series of powerful earthquakes have shaken Campi Flegrei, a volcanic field near Naples.
In May the region experienced their stongest tremor in 40 years with a magnitude of 4.4. Campi Flegrei itself last erupted in 1538.
Now, experts are warning that the number of earthquakes in the area is actually four times higher than previously thought. This means that more powerful, potentially devastating quakes could be imminent.
The Mail Online reports: Researchers used AI to provide precise earthquake location and magnitude information for the area in near real time.
They discovered four times as many earthquakes than earlier tools had detected, expanding the number recorded between 2022 and 2025 from 12,000 to more than 54,000.
‘These long faults suggest that an earthquake in the magnitude 5 range is not out of the question,” said study co-author Bill Ellsworth, who co-directs the Stanford Center for Induced and Triggered Seismicity.
‘We’ve known that this is a risky place for a long time, since the ’80s when part of the city was evacuated, and now we’re seeing for the first time the geologic structures that are responsible.’
Campi Flegrei, which translates to ‘burning fields’, last erupted in 1538. While it doesn’t erupt often, the volcano has shown signs of unrest in recent decades.
This volcanic region, which is home to more than 500,000 people, has experienced episodes of unrest dating back to the late 1950s.
The last period of unrest started in 2005, with a significant increase of the seismicity in 2018, including five earthquakes above a magnitude 4 in the first eight months of 2025.
The data revealed two faults converging under the town of Pozzuoli west of Naples, which has been continuously monitored since the early 1980s, when unrest caused the land to rise more than 6 feet and more than 16,000 earthquakes prompted evacuation of 40,000 residents.
In the past 400,000 years, Campi Flegrei has produced two of the largest eruptions in Europe.
The researchers said they have not yet seen any evidence for the upward movement of magma within the volcano, which reduces short-term concerns that it could erupt.
However, earthquakes still have the potential to endanger lives and damage buildings and infrastructure.
The researchers said knowing the location and length of a fault – the space between two blocks of rock that move and cause earthquakes – can help experts determine the range of magnitudes of future quakes.
‘Seismicity could change at any time, and that may be the most important thing about this study: this capability of getting a clear view is now operational,’ said study co-author Greg Beroza, a geophysics professor in the Stanford Doerr School of Sustainability.
When the volcano eventually erupts it is likely to be comparable in size to the eruption of Mount Vesuvius that destroyed the cities of Pompeii and Herculaneum, experts have previously said.
Other scientists have predicted that if this sleeping giant blows, it could create a plum large enough to plunge Earth into a global winter for years.
The latest findings were published in the journal Science.