Italian supervolcano stirs after 500 years of inactivity

A supervolcano that formed during the largest eruption in European history is showing signs that it is about to wake up and erupt again, according to a new study led by scientists from the National Institute of Geophysics and Volcanology (INGV) in Rome, Italy.

The caldera in question is known as Campi Flegrei, and according to The Guardian, it originally formed 39,000 years ago in a massive explosion that sent hundreds of cubic kilometers of debris into the air. The volcano, which is located near the city of Naples, hasn’t erupted since 1538 but is now showing signs of activity, the researchers reported on Tuesday.

Writing in the journal Nature Communications, INGV volcanologist Giovanni Chiodini and his colleagues explained that the 7.5-mile-wide caldera is close to reaching a critical point at which decreased pressure on rising magma results in outgassing (the unchecked release of gas that had been frozen, trapped or absorbed by other materials) and, potentially, an eruption.

Were that to happen, Chiodini told the Washington Post, it could be catastrophic for the 500,000 people living in Naples and elsewhere around the volcano. However, he noted, “volcanology is not a precise science” and that “many uncertainties” remain about the caldera’s behavior. “Long-term provisions are at the moment not possible,” he said. “The process that we describe could evolve in both directions: toward pre-eruptive conditions or to the finish of the volcanic unrest.”

Caldera’s behavior similar to other volcanos prior to eruptions

Chiodini’s team developed physical and volatile saturation models, then used the results of those models to demonstrate that magmatic volatiles which are released by decompressing magma at a critical degassing pressure (CDP) could drive what they call “volcanic unrest.”

At the CDP, they reported, the abrupt release of gasses could heat hydrothermal fluids and rocks. This heating, in turn, could be the catalyst for an accelerating deformation that ultimately results in rock failure and an eruption at the caldera, the study authors said.

Based on their observations, they believe that magma at Campi Flegrei could be nearing the CDP point. Furthermore, as the Washington Post noted, the increases in ground deformation and low-level seismic activity observed at the caldera are comparable to activity witnessed at other craters (Rabaul in Papua New Guinea and Sierra Negra in the Galapagos) prior to eruptions.

Both of those volcanoes, Chiodini told The Guardian, had demonstrated “acceleration in ground deformation before eruption with a pattern similar to that observed at Campi Flegrei.” While the INGV volcanologist could not specify when the Italian supervolcano might erupt, he emphasized that it would be “very dangerous” for those living nearby if and when it does.

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Image credit: Donar Reiskoffer/Wikimedia