(Newser) – A hidden "super volcano" near Pompeii threatens an eruption that could make Vesuvius look like a picnic, scientists warn. The Phlegraean Fields zone of intense seismic activity—which the ancient Romans believed was the gateway to hell—could doom millions of people in the Naples area if it erupts, Reuters reports. Scientists plan to drill more than two miles below its surface to monitor any signs of a pending eruption in the huge chamber of molten rock, but some experts fear that the drilling itself could trigger an earthquake or eruption.

Areas like the Phlegraean fields "can give rise to the only eruptions that can have global catastrophic effects comparable to major meteorite impacts" like the one that wiped out the dinosaurs, says the chief of the drilling project. The drilling, he says, will increase by up to 10,000 times "our ability to detect small episodes that are precursors of future eruptions." He considers those who fear the drilling "ill-informed," noting that projects seeking sources of thermal energy sent down dozens of less secure probes decades ago without incident. (Read more Vesuvius stories.)

