Wednesday, February 02, 2005

Mount St Helen's erupts!

A steam and ash eruption began about 1 hour ago - this is probably the lavadome fracturing and large slabs of material breaking off and falling away. Which would make this event similar to those seen at night causing bright flashes to occur in the crater. To following the event as it unfolds go to the Volcanocam website...


Anonymous Anonymous said...

Yeah, I saw it on the VolcanoCam too! Nice eruptive burst. I concur on the source, as it did not come from the vent where the magma is coming up, but rather from behind the highest portion of the new lava dome. So it is likely that the South face of the new lava dome suffered some collapse as the newer magma pushes over the top of the earlier layers laid down from October through December 16th, 2004.

Now, after the dome fractured in half and the NW portion was able to then uplift, it has been moving over it's earlier flows, again pushing upward and to the SE. It is at a point in it's movement that much of the highest portion has now reached where the earlier flow slanted downward against the back crater wall. As such, a very high but crumbling cliff is forming, and as the magma continues to push out of the vent at the NW edge of the new lava dome and moves SE, it will push more of it's material over the edge and it will collapse onto the glacier and South crater wall.

Thanks for your great videos and animations. They are excellent. To view my continuos updates you can go to the Weather Channel's message boards, look under the National Parks forum, and in the Mt. Saint Helens National Volcanic Monument thread. There I post photos, USGS analysis, and my own analysis of what is going on up there!

2005-02-02, 5:32 PM  
Anonymous Anonymous said...

The first eruptive burst started at 2:28pm, with an increase in smoke and steam in the crater, just to the right and behind the highest part of the new lava dome. 5 minutes later, the smoke was thicker and starting to spread above the dome just slightly. Then at 2:38pm the cloud of smoke and steam grew substantially, and by 2:43pm the darkest and strongest ash and rock was being expelled into the nearby areas of the crater, and also climbing over the crater wall to the East.

After this, the ash continued to build through 2:53pm, when it was at it's darkest and largest. After that, the ash started to disperse, but also move upwards and Eastwards, as well as filling the back of the crater.

An additional small burst of ash enhanced the thinning cloud at 3:08pm. Additional small bursts again enhanced the cloud of ash and steam at 3:28pm, and again from 3:43-3:48pm. The second strongest burst of ash then occured at 3:58pm, not as strong as the first burst, but clearly the second strongest.

After that, the ash started to thin at a more rapid rate and clear the crater, but occasional very mild bursts still occured for another 30 minutes or so.

Of note, several larger earthquakes (though not large) are evident on the webicorders at 7am, and again between 12 and 1pm. These may have been early precusors that indicated increased instability on the SE portion of the new lava dome.

Another fun day of volcano watching, to be sure!

2005-02-02, 5:48 PM  

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