Around 1.5 million people could be impacted by pyroclastic flows in the event of an eruption.
Known as the Campi Flegrei caldera, the threatening 13-kilometer-wide (8-mile) volcanic field sits beneath a densely populated area in Italy’s Campania region, with towns like Pozzuoli and part of the city of Naples built right on top of it. Unlike y... [2387 chars]