A massive supervolcano near Naples, Italy, is showing troubling signs of activity, prompting scientists to issue warnings about the potential for a catastrophic eruption that could affect millions of people.

Volcanoes remain among the most powerful and unpredictable forces of nature. Despite advances in science, forecasting when or how intensely they will erupt is still a challenge. Recent eruptions around the world—from underwater volcanoes in the Arctic to spectacular lava fountains in Hawaii—highlight just how volatile these natural systems can be.

Now, researchers are sounding the alarm about Campi Flegrei, a vast volcanic caldera located west of Naples. This ancient supervolcano, whose name means “burning fields,” is part of the same volcanic arc that includes Mount Vesuvius, which famously destroyed the city of Pompeii in 79 AD.

Mounting Signs of Activity

Over the past six months, scientists have detected more than 3,000 small tremors in the Campi Flegrei region. These small earthquakes are often a precursor to volcanic eruptions, as they reflect increasing pressure from magma beneath the surface.

In addition to seismic activity, there has been a significant rise in gas emissions. Researchers estimate that the volcano is releasing between 4,000 and 5,000 tons of carbon dioxide per day. While volcanic gas release is common, around 80% of this CO₂ appears to be magma-derived, suggesting molten rock is moving closer to the surface.

The Potential Impact

Should Campi Flegrei erupt, it could have devastating effects on the 4 million people living in and around the Naples metropolitan area. The eruption could produce powerful explosions, lava flows, and clouds of hot ash, damaging buildings and infrastructure in nearby towns like Pozzuoli.

In the aftermath, residents might face major disruptions to utilities such as electricity and water, making recovery efforts even more difficult. Perhaps the most concerning challenge is the unpredictability—scientists can detect warning signs, but the exact timing of an eruption remains uncertain.

Campi Flegrei last erupted in 1538, and while the hope is that it remains quiet, the growing evidence suggests that this ancient supervolcano is becoming restless once again.