December 20, 2006
Associated Press
VANCOUVER, Wash. (AP) - Like a giant smokestack, percolating Mount St. Helens let loose a billowing steam plume easily seen Tuesday in downtown Portland, Ore., about 80 kilometres away.
Photo: Closeup of a steaming Mount St. Helens, Vancouver, Washington. The plume results from condensation of warm moist air rising off the growing lava dome, and is visible from miles away when the air is cold and calm. (USGS Photo taken on December 19, 2006, by John Pallister)
Cold weather combined with the volcano's release of water vapour to make the display particularly impressive, scientists said. Mount St. Helens has been experiencing a low-key eruption since September 2004.
"You look at your industrial stacks around town and they're putting out nice vapour plumes today, as well," said volcanologist Willie Scott at the Cascades Volcano Observatory in Vancouver, about 260 kilometres south of Seattle and 80 kilometres from the mountain.
The white plume emitting from the snowy peak could be seen clearly against a blue sky.
The vapour temperature was near the boiling point of water - 100 degrees C - while temperatures at the mountain were around or below freezing, Scott said.
"The water vapour's condensing rapidly and it's making a very attractive plume," said seismologist Bill Steele at a University of Washington lab that has been monitoring the peak with the observatory.
Vapor has been rising from the volcano since before it rumbled back to life more than two years ago, extruding lava into the crater created when the mountaintop blew off in May 1980, flattening forests and killing 57 people.
http://reports.discoverychannel.ca/servlet/an/discovery/1/20061220/061220_discovery_mt_st_helens/20061220?hub=DiscoveryReport