MOUNT ST. HELENS NATIONAL MONUMENT, Wash. -- Mount St. Helens blew off more steam Monday, shooting a billowing white plume several hundred feet above the volcano and thrilling hundreds of visitors who had gathered below the rumbling mountain.
"Wow. It was amazing," said 9-year-old Alex Turchiano, who watched from a nearby visitors center. "I was hoping to see lava so I could see the trees fall down and the lava flow into the water. I wanted to see what it was going to do -- whether it would stop or keep going."
Scientists, who continued to warn that the volcano could blow at any moment, stopped short of calling the steam burst an actual eruption, saying no volcanic material apparently was emitted. The steam quickly dissipated and did not threaten any structures near Mount St. Helens.
Even if a larger eruption comes, officials say there was little chance of a repeat of the mountain's lethal 1980 explosion, or Hawaiian-style lava flows. The eruption 24 years ago blew 1,300 feet off the top of the peak, killed 57 people and coated much of the Pacific Northwest with ash.
Since Sept. 23, thousands of tiny earthquakes have shaken the mountain and several steam eruptions have occurred, the most seismic activity at the peak since the months following the 1980 blast. A burst of ash and steam on Friday was followed Saturday by a smaller plume of steam and a volcanic tremor. A smaller extended volcanic vibration was detected Sunday.
The latest burst came after scientists detected swelling in the 1.000-foot lava dome within the crater of the southwest Washington mountain. Steam rose to 10,000 feet, or nearly 2,000 feet above the rim.
"Hopefully after this clears away our crews will get a view of the crater, and the crater will probably be enlarged a bit," said U.S. Geological Survey geologist Willie Scott, who described it as a "very passive event."
Scientists speculated the steam was due to hot rock coming into contact with ice and snow contained in the glacier.
"Now most of us are convinced there's fresh magma down there," hydrologist Carolyn Driedger said.
Jeff Wynn, chief scientist for volcano hazards in nearby Vancouver, Wash., said the lava dome within the crater had risen another 100 feet in the dome's southern area.
"Something is driving -- like a piston -- something is driving up. We believe it's magma. We believe new magma is involved. And new magma is potentially more gas rich and therefore more explosive," Wynn said.
The action at Mount St. Helens has drawn thousands of visitors to the monument, including Patricia Cusic of Live Oak, Fla., who arrived Saturday with her daughter, and her three grandchildren who live in Arlington.
"Now we can go home and say, 'Hey, we saw a volcano erupting!' This was a good time to come," Cusic said excitedly at the Coldwater Ridge Visitors Center, about 8 1/2 miles from the rim.
During the weekend, officials shut down areas closer to the mountain as a precaution. The Johnston Ridge Observatory, about five miles from the crater, was evacuated, and most air traffic was prohibited within a 5-mile radius of the volcano.