In the opener of a series examining destructive natural forces, tornado survivors offer their accounts of the storms as they watch footage they risked their lives to capture.
See the deadliest volcanoes on the planet. Special effects take you inside some of the world's most famous eruptions. With spectacular new footage of lava rivers, superheated flying rocks, torrents of boiling ash and lethal mudflows.
Ordeals endured in snowstorms include a man who was trapped in his vehicle for 14 days; three mountaineers who escaped hurricane-force winds in Canada; and a man who survived a plane crash on a frozen lake and had to walk a mile to safety.