34 Supervolcanoes, Most Could Wipe Out Millions When They Erupt

Aira Caldera (Japan)

This 12-mile-wide caldera last erupted massively 22,000 years ago, but its active vent, Sakurajima, spews ash almost daily. About 600,000 Kagoshima residents live just 6 miles from this constant reminder of volcanic threat. Locals have adapted to the frequent grumbles and ash fall. The contrast of explosive ash plumes against delicate cherry blossoms creates a scene of beautiful danger.