Artificial intelligence has found that about 54,000 seismic events occurred under the Campi Flegrei, a supervolcano in Italy, from 2022 to 2025. Mapped epicenters revealed a huge ring-shaped fault, reports Live Science.
The new model has revealed previously unknown geological structures under the volcano, including a fault capable of generating earthquakes of about magnitude 5. Since the beginning of 2025, the region has experienced five tremors of magnitude greater than 4. The volcano has been acting restlessly since 2005. However, the AI-powered study found that most of the seismic events in the area had never been recorded before.
“We’ve known for a long time that this is a dangerous place. Now, for the first time, we’re seeing the geological structures behind it”, said study co-author and Stanford University professor emeritus of geophysics William Ellsworth.
Over the past 40,000 years, the Phlegraean Fields have produced two of the most powerful earthquakes in Europe. The volcano has been monitored since the 1950s, and monitoring was stepped up after a series of about 16,000 earthquakes in the 1980s that forced the evacuation of about 40,000 people.
To better assess today’s threats, researchers led by Ellsworth created a machine learning tool to detect events that traditional methods could not record. As co-author Greg Beroza explained, seismologists typically find earthquakes by analyzing seismograms and detecting sudden increases in amplitude, a process known as phase selection.
“This is a simple and often effective way to select phases, but it doesn’t ‘learn’ to do it better, so that it can improve over time. In our approach, we train a machine learning model to select phases. We draw on a collection of millions of examples where experts have already done it, and our method is designed to learn to do it more efficiently,” Beroza said.
Compared to traditional methods, which recorded about 12,000 earthquakes over the study period, the AI-based model detected significantly more events — about 54,000. Mapping these epicenters has revealed faults and fissures in the crust that can interact and cause tremors. In particular, scientists have identified two faults that converge under the city of Pozzuoli, west of Naples, where evacuations took place in the 1980s.
In addition, the researchers noted that Pozzuoli rose in the 1980s, and this process is now repeating itself: the ground under the city rises by about 10 centimeters every year. The area of uplift is surrounded by several cracks that form a distinct thin “ring fault” extending towards the sea.
The Phlegraean Fields are also mentioned in ancient Greek mythology. According to myth, the Gigantomachiya took place here – a battle between the gods, led by Zeus and supported by Hercules, and the giants.
