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Redoubt rumbles, alert level raised 16 March 2009

Posted by admin in activity reports, Alaska, Redoubt, United States.
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Redoubt 15 March 2009 (photographer Heather Bleick, AVO/USGS image)
Redoubt volcano on 15 March 2009. This view is of the north flank of the volcano, looking south. Ashfall is limited to the south crater floor and rim, and extends south-southeast. The source of the ash is a vent south of the 1990 dome at an elevation of ~2500m (photographer Heather Bleick, image courtesy AVO/USGS ). [source]

Alaska’s Mount Redoubt is back at aviation colour code Orange and alert level Watch today after a burst of activity yesterday afternoon: an increase in seismicity, and a steam-and-ash plume to around 4500m above sea level (Redoubt’s summit is 3108m above sea level, so the emission rose about 1500m on top of that). Here’s the bulletin from the Alaska Volcano Observatory, released at 14:50 local time yesterday:

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.

Based on [this] change in activity AVO is increasing the level of concern and alert level to ORANGE/WATCH.

It does not appear at this time that a significant eruption is likely in the short term, but conditions may evolve rapidly.

AVO is monitoring the situation closely and the AVO operations center in Anchorage is now resuming 24 hour per day staffing.

It seems no new magma has made it to the surface and there was no ash in the plume (although there was a small amount of ash – visible in the image above and in others of the AVO’s latest pictures – erupted from a small vent south of the 1990 dome), so this does not strictly count as an ‘eruption’. It is, however, a reminder that Redoubt is very much awake and active. The latest AVO update currently available (2009-03-16 00:04:04) reads:

Low level volcanic tremor has occurred continuously over the past two hours. Web camera images are dark.

Redoubt has not erupted, but has returned to the level of unrest observed during parts of late January and February.

The AVO operations center has resumed 24/7 monitoring of the volcano.

The tremor episodes can clearly be seen on the webicorder trace for the RSO station, reproduced below. The first of the two prominent episodes of tremor began at not long after 13:00, tailing off from around 16:00; the second, less intense, increased from about 22:15 and was still ongoing at 00:36.

Redoubt RSO webicorder trace 15-16 March 2009 (Alaska Volcano Observatory)

Check out Eruptions (as well as the AVO – and here, of course) for more information and updates.

[Thanks to a commenter who is Fishing in Juneau for dropping us a line about this one.]

For all our Redoubt coverage: Redoubt « The Volcanism Blog.

Redoubt alert status raised after explosionAnchorage Daily News, 15 March 2009
Redoubt code returns to orange after small explosionPeninsula Clarion, 15 March 2009
Redoubt rumbles againSeattle Times, 15 March 2009

Global Volcanism Program: Redoubt – summary information for Redoubt (1103-03-)
Alaska Volcano Observatory – Redoubt – AVO information and updates for Redoubt
Alaska Volcano Observatory – main page for the AVO

The Volcanism Blog


1. SHIRAKAWA Akira - 16 March 2009

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.

2. volcanism - 16 March 2009

Thanks for letting us know about the video, which is excellent. I’ve put up a separate post about the video to highlight it:


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