Mt. Fitzherbert

For more than a year, Mount St. Helens has been oozing lava into its crater at the rate of roughly a large dump-truck load – 10 cubic yards – every three seconds.

With the sticky molten rock comes a steady drumfire of small earthquakes.

The movement of lava up through the Southwest Washington volcano is "like a sticky piston trying to rise in a rusty cylinder," U.S. Geological Survey geologist Dave Sherrod said last week in a telephone interview from the agency's Cascades Volcano Observatory in Vancouver, Wash.

"These quakes are very small – we think they're associated with that sticking and slipping as the ground is deformed and relaxes."