Redoubt erupts (? ... !)

Date: February 07, 2009 Image Creator: Bleick, Heather Image courtesy of AVO/USGS.

So much for my oh-so-eloquent eulogy for early 2009 activity at Redoubt.

AVO reports that it appears that the volcano has potentially erupted - or at least released a lot of steam and (possibly) ash.

Seismic activity at Redoubt has increased since about 13:00 AKDT and is continuing. An AVO observation flight reported that a steam and ash plume rose as high as 15,000 ft above sea level and produced minor ash fall on the upper south flank of Redoubt. Last reports are that the plume is now mainly steam.

Doesn't seem like much of an event, although a plume of 15,000' (~5,000 meters) is notable (although a lot depends on the wind and air conditions at the time). If you check out the Hut webcam, you can see a strong, but much shorter, steam plume coming from the 1989-90 dome. It is hard to tell if this is, in fact, a true eruption - only if we have volcanic material in the plume would be want to count it as an "eruption", and it really isn't even as clear cut as that. This just seems to indicate that Redoubt was not as ready to settle back unto a lull as we all thought as recently as, oh , yesterday. AVO doesn't appear to think that is will directly lead to any increased chance of a major eruption following soon afterwards, but they have upgraded the status of the volcano back to Orange/Watch and returned to 24 staffing.

It is interesting to note that on Thursday AVO noted that "A Magnitude 4.0 regional tectonic earthquake occurred at 3:25 AKDT this morning (3/12), approximately 31 miles west-southwest of Redoubt." They went on to say that the event was not associated with the volcano. Now it is impossible to tell if there is any connection (if I could put this in big flashing letters I could - remember, earthquakes and volcanoes, although related, do not always cause each other to occur), but it is interesting to note. Most likely, it is a coincidence - the type that drives people like me nuts - but you never can tell.

UPDATE 3/15/09 7PM Pacific: The Anchorage Daily News has some more information about the, erm, "event" at Redoubt. Dr. Tom Murray of AVO says what I and many commenters have mentioned, that the "event" may not an actual eruption, mainly because the ash doesn't appear to be generated by new magma and the discharge wasn't explosive enough to be described as a full eruption.

UPDATE 3/15/09 9PM Pacific: Chris Waythomas from AVO was quoted in the Seattle Times that volcanic tremors returned for four hours today at Redoubt. This suggests that magma might be moving within the volcanic system, or possibly this might be merely related to the hydrothermal system - or both.

Look for updates here if this develops.

{Hat tip to Doug Cole for being on the ball.}

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Here we go... phreatic eruption....

That's often how it begins with those explosive volcanoes... The magma involved are so viscous, they take ages to reach the surface from the magma chamber...

Remember Mount Saint Helens? It took two months to get ready for eruption, but when it did...

Meanwhile, as magma slowly creeps up the pipes, groundwater flashes to steam as heat builds. That's probably what drove yesterday's eruption.

We still don't know what the volcano is up to... but it looks a bit closer to an impending kaboom.

Time will tell...

By Volcanophile (not verified) on 15 Mar 2009 #permalink

This does sound like a phreatic eruption ... a little too much water got a little to hot and an explosion ensued. The ash is mostly likely not juvenile (i.e., new magma) material, but just blasted-apart bits of the older dome. I guess Redoubt took exception to AVO's statement yesterday.

It will be interesting to see if AVO can determine if this was an eruption or merely a phreatic explosion. In any case, it is a new stage of activity for Redoubt during this period of increased activity.

not what I would call an eruption looking at the glorious webcam image just now.. I can't even see any debris deposits. She is certainly taking her time on this one. Sometimes I wonder if this sort of activity would even by noticed if it weren't for the seismic traces making us all jittery.

Redoubt may be enjoying the attention it gets as poster child for the importance of volcanic monitoring and research;)

The question of whether or not this apparently phreatic event was driven by new magma hinges on whether or not ash was erupted and when it can be analyzed. I can't imagine a better advertisement for funding analytical facilities and staffing them with people trained and experienced in using the instrumentation.

I can imagine the yells from the scientifically challenged: What are these "scientists" good for? They can even tell if a volcano has erupted.

By Lassi Hippeläinen (not verified) on 15 Mar 2009 #permalink

For those interested, yesterday I made a video of the event by combining images from the Hut webcam (automatically downloaded with a script) and sound converted from the seismic trace from RSO seismic station. The video (more like a slideshow with sound, though) starts at about 12:05 (Alaska time) and ends at 18:00, playing speed is 160x of real time. Audio and video are synchronized. Ash/smoke can be seen coming out the summit of the volcano when tremors start.

By SHIRAKAWA Akira (not verified) on 16 Mar 2009 #permalink

... "the discharge wasn't explosive enough to be described as a full eruption."

Is there an official standard of exactly how explosive it has to be before it qualifies as and eruption? What units of measure would you use to characterize that? Kiloton?