Mt. Fitzherbert

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," said Seth Moran, a seismologist with the U.S. Geological Survey's Cascades Volcano Observatory in Vancouver, Wash. "I never thought this eruption would last this long. And although things have slowed, there's no signs of it stopping any time soon." The slowdown is letting Moran and other scientists take a closer look at giant Mount Rainier and other potentially dangerous Cascade volcanoes and apply the lessons learned from Mount St. Helens.