Deadliest Volcanoes

Millions of people around the world live in the shadow of active volcanoes, under constant threat. From Japan's Mount Fuji to the "Sleeping Giant" beneath Naples to the Yellowstone "supervolcano" in the U.S., travel with scientists at work on these sites, attempting to discover how likely these volcanoes are to erupt, when it might happen, and exactly how deadly they could prove to be.