Volcanic growth spurts, just down the highway

Four months after Mount St. Helens stirred back to life -- drawing curiosity seekers from across the country -- the bulging, oblong dome inside the crater has ballooned to 350 feet high, with nearly a 50-degree slope in places.

The dome now contains enough solid material to fill KeyArena more than 100 times. At the peak of the flow, molten magma was being transformed into new rock pushing skyward at a rate of 11 yards per day.

Then earlier this month, an unexpected and significant explosion -- the biggest since October -- caught researchers by surprise and appears to mark some sort of transition on the sleeping giant's path to regrowth.

"'It makes me think a lot differently about the range of possibilities for the future,' geologist John Pallister said. 'We were anticipating a different event.'

"Volcanologists would not have been surprised if there had been a significant rockfall, a continuing hazard as sections of the new dome jut higher and stretch more than a thousand feet to the side. The explosive release of gas suggested that Mount St. Helens' plumbing is more finicky than first believed, that even slight changes in gas, or moisture below the surface, can trigger a new scenario.

"It's a reminder, said Jon Major, a research hydrologist at the Cascades Volcano Observatory, that "we've learned an awful lot about what we don't yet understand."