AI reveals hidden ‘ring fault’ that is unleashing earthquakes at Italy’s Campi Flegrei volcano
A artificial intelligence (IA) has revealed never-before-seen geological structures at Italy’s Campi Flegrei volcano, including an obvious “ring fault” that could trigger magnitude 5 earthquakes.
So far in 2025, Campi Flegrei has produced five earthquakes greater than magnitude 4, and the volcano has been destroyed. showing signs of trouble since 2005. But most earthquakes Triggered events in the region are going undetected, according to a new study that used AI to identify tens of thousands of seismic events that went unnoticed in recent years.
Over the past 40,000 years, the Campi Flegrei have produced two of Europe’s largest eruptions, and evidence suggests the volcano’s earlier history was just as explosive. Scientists have recorded unrest in the Campi Flegrei since the 1950s, but monitoring efforts intensified in the 1980s after a swarm of 16,000 earthquakes led to the evacuation of 40,000 residents.
To investigate modern threats from the Campi Flegrei, Ellsworth and his colleagues developed an AI tool that could identify earthquakes that previous methods could not detect.
Traditionally, seismologists identify earthquakes by analyzing seismograms, which are graphs with wavy lines representing ground shaking over time. Researchers look for a sudden increase in the size of the vibrations, and this process is known as “phase selection,” the study co-author said. Greg Berozaprofessor of geophysics at Stanford University.
“It’s a simple and often effective way to pick a phase, but it doesn’t teach you how to do it better so that it improves over time,” Beroza told Live Science in an email. “In our approach, we train a machine learning model to select phases. We base it on the collection of millions of examples where experts have already done it, and our method is designed to learn how to do it more efficiently.”
The team chose to let their tool analyze the Campi Flegrei before the others volcanoes for several reasons, including the urgent need to better understand the behavior of this volcano, Beroza said. More than 360,000 people live in the 11-kilometer-long Campi Flegrei caldera, and around 1.5 million people reside in the wider area. The unrest of the past 20 years intensified in 2018 – and while there are currently no signs of an eruption, a particularly strong or shallow earthquake could pose enormous danger to people and damage buildings, the statement said.
The results of the AI tool, published on September 4 in the journal Sciencereveal that three quarters of earthquakes occurring in Campi Flegrei between 2022 and mid-2025 were not detected. While traditional methods documented 12,000 earthquakes during this period, AI shows that number was closer to 54,000.
By mapping the location of these earthquakes, researchers discovered faults – cracks in the Earth’s crust that can crush against each other and cause earthquakes – that previous methods had not found. Notably, the team discovered two faults converging beneath Pozzuoli, a town west of Naples where evacuations took place in the 1980s. The location of these faults suggests that “a magnitude 5 earthquake is not out of the question,” Ellsworth said.
This is not the only striking discovery. Pozzuoli boomed in the 1980s, and the same thing is happening again nowwith the ground beneath the city rising about 4 inches (10 centimeters) each year. The uplift zone appears to be surrounded by several faults, forming a thin, well-marked “ring fault” that extends offshore, according to the release.
“Our Italian colleagues were surprised to see the ring so clearly,” lead author of the study Xing Tana doctoral student in Beroza’s lab, said in the release. “They expected to see something in the south where previous data had revealed scattered seismicity, but in the north they had never seen it so clearly.”
Seismic activity along the ring fault could help predict changes in the system, as well as provide insight into the magnitude of future earthquakes, Beroza said. But this does not provide new information about the likelihood or timing of the Campi Flegrei’s next eruption.
“All seismicity analyzed from 2022 to mid-2025 is shallow, at depths greater than 4 kilometers (2.5 miles) and indicates no migration of magma to the surface,” Beroza said.
The team’s results for Campi Flegrei indicate that the AI tool could also be useful for other volcanoes. Locations that have recently experienced a slight increase in seismic activity, like Santorini in Greececould benefit from a clearer understanding of the underlying geology, the researchers said in the release.
