Mount St. Helens eruption is officially over, experts say

[Amelia]

Mount St. Helens eruption is officially over, experts say

Thursday, July 10, 2008

By TERESA BLACKMAN, kgw.com Staff

VANCOUVER, Wash. -- It shook, steamed and shot out lava on and off for about three years, but now the experts believe Mount St. Helens is going back to sleep, for the most part.

A statement released by the U.S. Geological Survey team Thursday said “the more than three-years-long, lava-dome eruption of Mount St. Helens that began in autumn 2004 and paused in late January of this year appears to have ended.”

USGS also announced Thursday that it had lowered the alert level for the volcano to "normal," signaled by the color green.

Geologists studying the lava dome said that five months have passed with no signs of renewed eruptive activity and earthquakes, volcanic gas emissions, or ground deformation.

They added that they had watched the rate of lava-dome growth gradually decline throughout the eruption, which accounted for at least 93 million cubic meters of new lava, or a volume that would cover seven lanes of highway from New York City to Portland.

But now that the eruption is over, that doesn’t mean the mountain will remain entirely at rest.

“Even with the end of lava dome growth, some hazards persist,” the press release warned. “The new lava dome remains hot in places-capable of producing small hot avalanches or minor explosions that could dust areas with ash up to tens of miles downwind.”

It went on to say that rock fall from the crater walls coulc produce clouds of dust that rise above the crater rim and heavy rainfall or rapid snowmelt could send small debris flows onto the Pumice Plain north of the crater.

The U.S. Geological Survey team and University of Washington researchers said they will continue to monitor the situation closely and will issue additional updates if necessary.

The eruption started in the fall of 2004 and pushed 125 million cubic yards of lava into the crater.

In the past 28 years, lava has replaced about 7 percent of the mountaintop that was removed in the 1980 blast.