The Earth has more than 1,500 potentially active volcanoes, quietly simmering under the surface or even along the ocean floor. Some, such as Hawaii’s Kilauea, are in a continual state of low-level eruption. Others, like Oregon’s Mount St. Helen’s, have erupted more destructively in the past century. It’s the supervolcanoes, however, that cause scientists the most concern. Supervolcanoes are large volcanoes with the potential to cause catastrophic damage on a continental, even global, scale if they erupt. In Italy, the Campi Flegrei supervolcano may be getting ready to show us exactly what that looks like.
Campi Flegrei (“flaming fields”) is located nine miles away from Naples, on the other side of the city from Mount Vesuvius, another supervolcano that erupted in 79 AD. Campi Flegrei isn’t a mountain, but a large depression that contains 24 craters and edifices. It last erupted in 1538, after nearly a century of pressure built up.
Scientists from University College London and the Vesuvius Observatory say the supervolcano “may be approaching a critical stage.” Christopher Kilburn, director of the University College London Hazard Center, and author of a study recently published in Nature Communications, said, "By studying how the ground is cracking and moving at Campi Flegrei, we think it may be approaching a critical stage where further unrest will increase the possibility of an eruption, and it's imperative that the authorities are prepared for this.”
That doesn’t mean Italians should flee their homes. “For all we know, the volcano won’t do any more,” said Kilburn. “We might not have any more problems for another 500 years. But if we go into another rapid uplift, like we’ve seen in the past, we just have to bear in mind that…it might be taking to a state closer to an eruption. The probability would be higher.”
Campi Flegrei has been under study for more than 500 years, and the eight-mile-wide caldera has been “restless” for nearly 70 years, showing signs of activity through small earthquakes throughout the 1950s, 1970s, and 1980s. It could release pressure in small, non-eventful eruptions and never build up a catastrophic amount of pressure.
Even so, nearly a million people live in Naples, and there are 360,000 people living across Campi Flegrei’s caldera. Even a minor eruption in a crowded urban area has the potential to unleash tremendous damage. Scientists worry that subtle pre-eruption activity spread over years or decades may have desensitized residents to the threat. Also, the fact that the supervolcano is not a mountain makes the extent of its damage area less easy to predict.
“We’ll have to evacuate more than the area that’s likely to be affected because they won’t know quite where it’s going to come out until the last moment, whereas a volcano like Vesuvius the magma normally comes out of the top.”
For now, the Italian government is preparing by raising the threat alert from green to yellow, indicating that the situation requires scientific monitoring. Residents should consider themselves warned.