Tragedy struck at the Solfatara volcano crater north of Naples a few weeks ago. An 11-year-old boy climbed over a low, wooden fence, ventured onto the chalky moonscape, and fell into an open fissure. His parents frantically tried to pull him out, just as the hollow floor of the crater crumbled, sending them all to their deaths in a gaseous pit of boiling gray mud, as the family’s seven-year-old boy watched in horror. The accident was a freak occurrence, responsible for the only recorded deaths on this crater in centuries.

But those hot gases hold an ominous story: Solfatara is part of the massive Phlegrean Fields, a threatening supervolcano experts agree could begin erupting anytime. Phlegrean Fields—a network of two dozen craters and other volcanic structures—is especially worrisome because the nested craters stretch under the Gulf of Naples, right alongside the greater Naples metropolitan area, home to more than three million people. Much like Yellowstone in Wyoming and Long Valley in California, Phlegrean Fields is classified as a supervolcano that, when (not if) it next erupts, could cause a catastrophic global event. READ MORE