Washington State, USA
Image: Gases escape the growing dome inside the Mount St. Helens' crater overlooking Spirit Lake in June. Mount Rainier is in the background.
Mount St. Helens just won't quit. Three years ago this month, hundreds of small earthquakes heralded the renewal of volcanic activity at the Cascade peak after an 18-year lull. Since then, the volcano has been a perpetual-motion machine. "It's been an amazing run. I never thought this eruption would last this long. And although things have slowed, there's no signs of it stopping any time soon...Mount St. Helens woke up in a hurry three years ago, which shows that we have to be prepared for what these volcanoes can do. You want to be ahead of the game by being able to detect even small changes." Tens of earthquakes are occurring daily compared with hundreds a year ago. The volcano's slowdown has allowed volcano scientists to give more attention to Mount Rainier, which is considered the Cascades' most dangerous volcano because it poses a threat to a large population.