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  • From: "Toni Hawryluk" <tonihawr AT msn.com>
  • To: "Homestead mailing list" <homestead AT lists.ibiblio.org>
  • Subject: [Homestead] update-on-volcanoes 'lesson'
  • Date: Fri, 26 Nov 2004 10:53:55 -0800

http://www.msnbc.msn.com/id/6587168/<http://www.msnbc.msn.com/id/6587168/>



Mount St. Helens is fast growing its new top

By MIKE LEWIS

The Seattle Post Intelligencer

USA - While on most late fall days the clouds obscure new growth, the meters
on the mountain don't lie: Mount St. Helens continues to build a new
mountaintop at a rapid rate. According to recent reports from the U.S.
Geological Survey, the lava dome had grown to nearly 800 feet high and covers
70 acres in the volcano's mile-wide crater. Geologists say the subsurface
magma, the cause of the recent steady stream of earthquakes and steam that
began in late September, is pushing the dome skyward with no indication of
letting up.

At the current pace, the mountain could have a new top in less than two
decades. But geologists have no idea how long the activity will last.

Recent thermal imaging shows that the new lobes forming on the dome are
rising at a rate of 30 feet a day. The highest point in the new dome is 7,400
feet, according to recent data from instruments placed in the crater. At its
highest point, the mountain is 8,364 feet. Before the 1980 eruption that
killed 57 people, it stood at 9,677 feet.

During the past two weeks, seismic activity has increased slightly. While
still not matching the temblors that shook the observation centers two months
ago, the seismometers have detected crater floor earthquakes at a magnitude
of 2.8. This is a marked increase from low-level activity in mid-October that
diminished seismic readings and subsequent public interest.

Todd Cullings, assistant director of the Johnston Ridge and Coldwater Ridge
visitor centers, said in a recent interview that activity in the centers has
slowed considerably, but people still remain curious about the eruptions.

"When we have a nice day, they still come," he said.

The increasing activity, geologists say, doesn't appear to indicate an
increased likelihood of an explosive eruption. The lava reaching the surface
is "gas poor," meaning that its capacity to explode is minimal.

But according to a USGS alert issued early this week, while explosive
eruptions are unlikely, they are not impossible. Also, the lack of gas does
not mean activity has slowed.

"The steep west face of the dome is crumbling piecemeal but, as fractures
grow, there is an increased chance of large slabs of hot rock toppling
westward and forming ash clouds that drift out of the crater and hot
avalanches, or pyroclastic flows," the alert noted.

However, scientists said that as the dome pushes upward and crumbles aside,
there isn't yet a threat of downstream mudflows resulting from the glowing
rock coming into contact with the crater's glacier.


--------------------------------------------------------------------------------

P-I reporter Mike Lewis can be reached at 206-448-8140 or
mikelewis AT seattlepi.com



  • [Homestead] update-on-volcanoes 'lesson', Toni Hawryluk, 11/26/2004

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