Read More: Net Geo
A long-quiet yet huge supervolcano that lies under 500,000 people in Italy may be waking up and approaching a "critical state," scientists report this week in the journal Nature Communications. Based on physical measurements and computer modeling, "we propose that magma could be approaching the CDP
at Campi Flegrei, a volcano in the metropolitan area of Naples, one of the most densely inhabited areas in the world, and where accelerating deformation and heating are currently being observed," wrote the scientists—who are led by Giovanni Chiodini of the Italian National Institute of Geophysics in Rome.
A sudden release of hot magmatic gasses is possible in the near future, which could trigger a large eruption, the scientists warn. Yet the timing of any possible eruption is unknown and is currently not possible to predict.
In response to the news, Italy's government has raised the volcano's threat level from green to yellow, or from quiet to requires scientific monitoring. In other words, the government is urging a measured response to the study, followed by additional scientific work.
Campi Flegrei means "burning fields" in Italian. The volcanic region is also known as the Phlegraean Fields. Like other supervolcanoes—such as the one responsible for the geothermal features of Yellowstone—it is not a single volcanic cone. Rather, it's a large complex, much of it underground or under the Mediterranean Sea, that includes 24 craters, as well as various geysers and vents that can release hot gas.