Posted on 10/07/2004 1:04:20 PM PDT by Ernest_at_the_Beach
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 Mount St. Helens' Crater Floor Rising
By GENE JOHNSON, Associated Press Writer MOUNT ST. HELENS, Wash. - Part of Mount St. Helens' crater floor has risen 50 to 100 feet since Tuesday while earthquake rates have been low, signs that magma is moving upward without much resistance, scientists said Thursday.
"The skids are greased," Jake Lowenstern, a U.S. Geological Survey (news - web sites) volcanologist, said at a news conference at the Cascades Volcano Observatory in Vancouver, Wash.
With the latest rising, an area of the crater floor just south of the nearly 1,000-foot lava dome has risen about 250 feet since the mountain began stirring two weeks ago, Lowenstern said.
There's no way to tell when magma might reach the surface, he said.
On Wednesday, scientists lowered the alert level for the southwest Washington volcano, saying earthquake activity was down to the lowest level since before the mountain started venting steam last week.
U.S. Geological Survey scientists downgraded the "volcano alert" to a "volcano advisory," indicating the probability of an eruption that could endanger lives and property had decreased significantly since Saturday, when thousands of people were evacuated from the mountain.
Despite the new detail Thursday on the magma movement, scientists said there was no reason to raise the alert level back up.
Larry Mastin, a USGS (news - web sites) expert in the physics of volcano eruptions, said that while there's an outside chance an eruption could send a plume of ash 15 miles into the air or higher, there is no indication that any eruption is imminent or that it would threaten lives or property.
Earthquake activity remained relatively low Thursday, with about one magnitude 1 quake a minute. The volcano was occasionally venting steam as water trickled down and hit hot rocks, Lowenstern said.
Scientists planned to make another flight over the volcano's crater Thursday to sample gas emissions and take thermal images, and to continue preparing instruments on the mountain for the winter.
A brief break in the clouds late Wednesday gave visitors a peek at weak steam emissions in the volcano's crater.
On Tuesday, under sunny skies, a spectacular cloud of steam and old ash rose thousands of feet above the 8,364-foot peak and a light dusting of gritty ash fell on some areas northeast of the mountain. It was the largest of a series of emissions of steam and ash since Friday.
Geologists continued to emphasize that there is little chance of anything similar to the blast that blew 1,300 feet off the top of the peak in May 1980, killing 57 people and paralyzing much of the inland Pacific Northwest with gritty volcanic ash.
Before then, Mount St. Helens had been silent since the 19th century.
The U.S. Forest Service reiterated Thursday that closures around the volcano — including the Johnston Ridge observatory five miles north of the crater — would remain in effect until authorities determine the area is safe.
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On the Net:
U.S. Geological Survey regional site: http://vulcan.wr.usgs.gov/Volcanoes/Cascades/CurrentActivity/
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Now you listen to me Mr. Mayor. If that alert level goes up my tourist trade disappears. And if that happens, you can forget about my usual... ahem... con-tri-bu-tion come campaign time! Am I gettin' through, your honor?
< 'Jaws' mode = off >
(steely)
VA Beach? I just had lunch last week at the Duck-In. My, how the sand dunes have changed. lol
Not possible. It is a stratovolcano. They do explosions no matter what, not lava flows.
yet they say they don't know how far the magma has risen....but then say don't worry, no eruption is imminent.
lol
It is a TREAT!! When St. Helens is covered with snow it kind of looks like a huge snow cone. It will look different now with the blow out area bigger than before the 1980 blast. Look for pictures of this mountain before all of this happened....it was absolutely a knockout mountain with huge old growth timber and many mountain lakes. The lake nearest the blow area was raised 2000 feet. It's name was Spirit Lake...really a beautiful place before the blow.
From CVO Glossary:
Some of the Earth's grandest mountains are composite volcanoes -- sometimes called stratovolcanoes. They are typically steep-sided, symmetrical cones of large dimension built of alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs and may rise as much as 8,000 feet above their bases.
Guess the 'Preparation V' is doing the job!
Well, yes, they do have some. But, they are known for their explosivity. The lava flows do not travel near as far either.
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