Tungurahua Eruption, Ecuador

Volcano Tungurahua in Ecuador erupts about every 90 years—it's a schedule the mountain has kept for 1300 years. This photo was taken by Patrick Taschler in 2006. (Via Astronomy Photo of the Day and Alexandra Witze)

The Ring of Fire

We're not talking about Johnny Cash....we're talking about volcanos and subduction zones, all that geological stuff.