Mount Redoubt Volcano

[AKDenise]

.............I don't really have a good explaination why the ash shows evidence of reation to ground water, and some of the other fragments do not. It's possible that they had solidified before the ground water had been reached.

From PBS, here's nice explanation of the water carried down with subduction and it's impact:

(snipped from http://www.pbs.org/wnet/savageearth/...oes/index.html)

The world's most explosive -- and devastating -- volcanic eruptions usually occur in subduction zones, because subducting oceanic plates are soaked with water, and that water helps the overlying rock melt. Ultimately, the result is a particularly gassy magma. This andesitic magma, as it is called, is very viscous -- that is, resistant to flow, like maple syrup compared to water. Such is the case in the Cascades Range of the Pacific northwest, the home of Mount St. Helens and 14 other large volcanoes.

Andesitic magma is not explosive in and of itself. But it does impede the escape of gases out of the magma chamber. Their migration inhibited, the gases form bubbles and pockets in the magma. Eventually, the pressure of the collected gases rises so high that they blow through the magma like a cork out of a champagne bottle. The result is an explosion of gas, ash, and fiery fragments of volcanic rock.

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[geonuc]

From PBS, here's nice explanation of the water carried down with subduction and it's impact:

(snipped from http://www.pbs.org/wnet/savageearth/...oes/index.html)

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While PBS describes andesitic magma reasonably well (all of which I'm sure dgavin is quite familiar with), the snippet you quoted doesn't have much to do with the interaction of rising magma and groundwater.

[AKDenise]

While PBS describes andesitic magma reasonably well (all of which I'm sure dgavin is quite familiar with), the snippet you quoted doesn't have much to do with the interaction of rising magma and groundwater.

True, it's only the first of a 2 or 3-step opportunity to interact with water. It was a further clarification of my statement on H2O in subduction.

BTW all....the big reaction on the Redoubt seismograms at 12:13 PM is a 4.7 local earthquake.

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[dgavin]

Just some updates. Whiles Redoubt is still venting, it seems to be venting mostly steam since about the 5th, and very little ash.

Some nice view on the webcams today! http://www.avo.alaska.edu/webcam/index.php

I have been researching to see if there were other volcanoes that seems to have hydrothermally driven eruptions like this, and there does appear to be at-least one other. Source: http://www.cas.usf.edu/~cconnor/vg@usf/masaya.html

There is even a word for these types of eruptions. Phreatic and Phreatomagmatic Eruptions. After reading that source and then thinking over Redoubt's patterns, I'd say it fit and has exhibited both Phreatic and Phreatomagmatic types of eruptive activity.

Granted one source is not enough to support anything, but at least I wasn't climbing up the wrong side of a volcano with my hydrothermally driven activity model.

[dgavin]

USGS has confirmed a new lava dome at Reboubt. Still no good pictures of it yet.

[dgavin]

A Picture clearly showing the new lava dome.

http://www.avo.alaska.edu/image.php?id=18108

USGS got quite a bit done over the weekend. Night photography of the lava dome confirmed a very faint incadesence. The RSO seismograph station is back online, the RSO station was damaged during the eruption on march 23. They were finaly able to get someone into the crater to repair it.

[geonuc]

It's interesting how new lava domes often look like just a pile of dirt. A smoking pile of dirt.

[dgavin]

Interesting developments in science back from the volcano.

One of the USGS scientists did find the debris field of a pyroclasstic event from the eruptions, so it look like all my original predictions are confirmed.

I've been comparing images on the web cams, and there is a definite and noticeable swelling of the left summit (as seen from HUT camera). Additionally part of that left peak is showing alterations from Lahars and Mud Flow activity. Compared to images earlier it looks like there is now a height difference in the left peek from the right peek of close to 30 meters from previous images. This is just a best guess. also the left side of mountain near the summit has evidence of swelling out.

Usually swelling happens before eruptions, so this is a bit different.

I'd say one of two things are going on here. The lava dome is not releasing pressure fast enough, and magma is building up inside Redoubt, or two, there is another chimney the magma is following that has not found an outlet vent yet.

It sort of hints that we may not have seen the main eruption after all. If the bulging continues, we could be looking at an event similar to St. Helen's down the road at some point.

[geonuc]

It sort of hints that we may not have seen the main eruption after all. If the bulging continues, we could be looking at an event similar to St. Helen's down the road at some point.

If so, let's hope the shotgun blast is not aimed towards the east.

[Stroller]

Looks like Dgavin is on the money:

http://scienceblogs.com/eruptions/20...s_big_boom.php

If it's when rather than if, Jun 10 or July 7 are the dates to watch for I think.

[dgavin]

Looks like Dgavin is on the money:

http://scienceblogs.com/eruptions/20...s_big_boom.php

If it's when rather than if, Jun 10 or July 7 are the dates to watch for I think.

It may be sooner then that, they put out a VAN notice yesterday that I hadn't...ummm noticed

Basically saying that an explosive eruption is very likely.

http://www.avo.alaska.edu/activity/r...id=4090&type=3

[CJSF]

Looks like Dgavin is on the money:

http://scienceblogs.com/eruptions/20...s_big_boom.php

If it's when rather than if, Jun 10 or July 7 are the dates to watch for I think.

I'm lazy... what's particularly significant about those 2 days?

CJSF

eta: actually, I can't get the page to load anyway.

[dgavin]

Probably a full moon or something like that.

[PetersCreek]

There was a Bad Volcano Science moment on the radio this morning. The station reported that according to the Alaska Volcano Observatory, seismic activity had tapered off somewhat but that it was still higher than it has been all week. Excuse me? Activity has reduced...but is still higher than before it reduced? Come again?

[Stroller]

Probably a full moon or something like that.

Full moon early hours tomorrow. Apogee next tuesday

Redoubts initial big eruption occurred near a full moon apogee IIRC, but the forces driving this latest threat are much closer to home, - Earth's gravity and increasing magma pressure. So it's anyone's guess, place bets now!

[dgavin]

As of this morning, Mountain Redoubt had been place on condition Yellow alert, after a seiries of small earthquakes were detected at the summit of the moutnain. The earhtquakes have been continuing on for the whole day.

I'll post more soon as more is available.

[dgavin]

The number of earthquake events at the summit of Mt Redoubt has been decreasing steadily. Web cam's have been cloud filled for both days so nothing to view there either. Condition remains at Yellow, but no indications yet of any steam or ash venting.

[dgavin]

While the siesmograpgh readings have tapered off, one of the webcams is not obscured today and Mount Redoubt is definately in the middle of a Steam/Gas Eurptive phase. Uncertaine as to the size and power, but from appearances in the web cam, it's fairly minor of an event. For now.

http://www.avo.alaska.edu/webcam/Redoubt_-_Hut.php


*Edit to Add*

Most the snow has melted off the other web cam today, so it's no longer obscured either.

http://www.avo.alaska.edu/webcam/Redoubt_-_DFR.php

[dgavin]

Redoubt still steaming this morning. AVO reporting that the small swarm continues with about 8 quakes every 10 minutes. Condition remains at Yellow.

[Squink]

http://www.avo.alaska.edu/webcam/Redoubt_-_Hut.php
http://www.avo.alaska.edu/webcam/Redoubt_-_DFR.php

Best views in weeks!
The waterfall under the dome (hutcam) looks to be back in action.

[dgavin]

Siesmic activity is back to background lavels, almost, and the steam emission are ruducing in size/amount. AVO is saying the don't think it's very likely to lead to an eruptive phase. Reboubt staying at condition Yellow for now however.

[dgavin]

Mt. Redoubt has been placed back to condition Green today.

[Squink]

Redoubt is showing a nice plume today, despite being at condition green:
redoubt-3.jpg

[dgavin]

wow not even a notice on VONA for it yet, thats a surprise considering it's closness to airline routes. If it continues I suspect they'll upgrade it to Cond Yellow in a few days.

[publiusr]

Something called volcano monitoring indeed.

Any news from Mt. Spurr? Still quiet?