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What is happening at Gareloi? 28 March 2009

Posted by admin in activity reports, Alaska, Gareloi, United States.
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[UPDATE: It seems that ‘what is happening at Gareloi’ is that it is blowing a gale. The trace below appears to be a particularly dramatic example of what a good strong blow looks like on a seismograph. Further update, this has been confirmed by AVO. Additional update, AVO have added a note to the Gareloi webicorder page explaining that their equipment is being affected by wind. To stop people getting over-excited about eruptions that aren’t happening.]

Gareloi is a remote volcano in the Delarof Islands, at the far western end of the Aleutian Islands chain. Its recent history has seen fairly frequent eruptions, the most recent eruption (disregarding an unconfirmed event in 1996) being in August 1989. Monitoring there consists of a single seismometer, which is readable through a webicorder trace on the AVO website. Here is a screenshot of the current trace:

Gareloi volcano webicorder trace 27-28 March 2009 (AVO/USGS)

That looks like an eruption, and a sizeable, sustained one at that. Increasing seismicity – tremor interspersed with discrete quakes – from around 23:00-00:00 GMT on 27 March, rising to saturate the graph from around 04:00-04:30 GMT today, and still ongoing.

The status of this volcano remains Green at the moment, there are no volcanic ash advisories from Anchorage or Tokyo, and there is no word on this activity from the AVO.

[Thanks to Ton van der Aa who spotted something going on at Gareloi. Also see Fresh Bilge for more on this apparent activity.]

Global Volcanism Program: Gareloi – summary information for Gareloi (1101-07-)
Alaska Volcano Observatory – main page for the AVO

The Volcanism Blog


1. SHIRAKAWA Akira - 28 March 2009

Audio/spectrum analysis could help understand better the nature of these signals instead of the webicorder/waveform display, but unfortunately the servers I use to download seismic traces appear to be down at the moment. I’ll post an audio sample and a screenshot of the spectrum trace of the last hours of activity at Gareloi later, when (if?) I’ll manage to download the seismic trace of GAEA station.

2. Guillermo - 28 March 2009

I’m not an expert, but could be these registries caused by a strong wind or something like that, that “shakes” the instrument? The zone is frequently affected by strong storms, and now perhaps occured a problem.

I heard that even a seawave can be recorded in a seismometer.

3. volcanism - 28 March 2009

Yes, I wondered if it was wind. But it’s a very sustained and consistent wind if it is … possible, though, at island such as Gareloi? Or just a broken seismometer.

4. Ron de Haan - 28 March 2009
5. volcanism - 28 March 2009

Thanks for the link to that discussion, Ron … if Gareloi was definitely erupting, and had been for hours, then I can’t help thinking the AVO would have said *something* by now.

Looking closely at the seismic trace, it does seem that there is no increase in the frequency of the small earthquakes (it’s hard to pick out among the rising tremor, if indeed it is tremor).

6. Ton van der Aa - 28 March 2009

Well i hoped it was a eruption I am looking on the webicorder for redoubt for the last two days when i had time and was happy to witness the last 2 eruptions.But then i went trough all the webicorders and found this one at galeroi.But it says they restored the webicorder like yesterday so maybe something went wrong after a couple of hours.Most likely i believe it is that.But what i hope is off course that it was not for nothing avo restored this thing maybe they where on to something and restored it just in time .But at least it looks scary and if that really represents what is going on there i just think we would have known by now cause it must be big then……i think…

7. Boris Behncke - 28 March 2009

I can tell that here on Etna when there’s strong wind on the volcano, it produces quite a conspicuous signal, which often leads to people calling our institute to know what’s happening. I also remember that at some time this winter, the Redoubt webicorders showed similar signals, and they were explained with heavy wind. I can imagine that in that remote area where Gareloi is located weather conditions can get pretty intense.
You should visit the AVO photo gallery where there is now a series of really impressive photos showing lightning in last night’s eruption plumes from Redoubt: http://www.avo.alaska.edu/images/recent_images.php

8. wattsupwiththat - 28 March 2009

I just called AVO. As I speculated, a windstorm.


9. Ton van der Aa - 28 March 2009

And the webicorder on Tanaga just acts normal and thats the closest to galeroi , so i guess they have to go back and restore the thing again….like they don’t have nothing else to do….ah well on there way if they just go to mount redoubt and dust of the webcam….the show must go on……..right??

10. Boris Behncke - 28 March 2009

In fact, AVO has a note above the Gareloi webicorder image: “NOTE: MARCH 28, 2009, GARELOI WEBICORDER AFFECTED BY HIGH WINDS”
Wouldn’t wish those poor folks at AVO another eruption at the same time as Redoubt – the’ve already been under pressure last year with Okmok, Kasatochi and Cleveland and I know what it’s like to have ONE volcano erupting in a potentially dangerous way.

11. Brian Owens - 29 March 2009

The same thing happened a few months ago with Yellowstone. You all remember there was a real swarm of quakes, but at times it looked like there were “harmonic” tremors, but that was also a case of the wind effecting the seismographs.

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