AI Reveals Hidden Faults at Campi Flegrei Volcano

Recent advances in artificial intelligence (AI) have uncovered previously unknown geological structures beneath Italy’s Campi Flegrei volcano. This discovery includes a distinct ring fault that could trigger magnitude 5 earthquakes. Campi Flegrei has shown signs of unrest since 2005 and produced five earthquakes above magnitude 4 in 2025 alone. Using AI, scientists detected tens of thousands of smaller quakes that traditional methods missed. This new insight improves understanding of the volcano’s seismic risks and underlying geology.

Background and Volcanic Activity

Campi Flegrei is a large caldera west of Naples, Italy. It has a history of powerful eruptions over the past 40,000 years, including two of Europe’s largest. Since the 1950s, scientists have monitored its activity closely. In the 1980s, a swarm of 16,000 earthquakes led to the evacuation of 40,000 residents. The volcano’s unrest has persisted, with ground uplift and increased seismicity noted in recent decades.

AI-Based Seismic Detection

Traditional earthquake detection relies on analysing seismograms for sharp changes in ground shaking, a process called phase picking. However, this method misses many small quakes. Researchers developed an AI tool trained on millions of expert-labelled examples to improve phase picking. This machine learning model identifies many more seismic events and provides a clearer picture of underground activity.

Key Discoveries from AI Analysis

Between 2022 and mid-2025, traditional methods recorded about 12,000 earthquakes at Campi Flegrei. The AI tool revealed the actual number was closer to 54,000. Mapping these quakes exposed new faults, including two converging beneath Pozzuoli, a town previously evacuated. These faults form a ring fault encircling the area of ground uplift. This ring fault extends offshore and may produce earthquakes up to magnitude 5.

Implications for Volcanic Risk

The uplift beneath Pozzuoli is rising about 10 centimetres annually, surrounded by the ring fault. Seismic activity along this fault could help forecast changes in the volcanic system and potential earthquake magnitudes. However, current seismicity is shallow and shows no signs of magma moving closer to the surface. Thus, the AI findings do not predict an imminent eruption but show earthquake risks.

Broader Applications of AI in Volcanology

The success of AI at Campi Flegrei suggests it can be applied to other volcanoes with increasing seismic activity. For example, Santorini in Greece could benefit from similar analysis. AI can enhance monitoring by detecting subtle seismic signals, improving hazard assessment and early warning systems worldwide.