Activity in Iceland’s Dead Zone

Photograph by Skúli Thor Magnusson. Stunning view of the Veidivötn Lakes.

The Dead Zone

In the area going from Vatnajökull down to Torfajökull and Myrdalsjökull there is normally almost no seismic activity. This has given the area the not so scientific name of the Dead Zone. It contains the fissure swarms of Bárdarbunga, Grimsvötn and Katla. Grimsvötns fissure swarm is called Laki and Katlas is called Éldgja.

Veidivötn

Bárdarbungas fissure swarm is called Veidivötn, and has had the largest lava-floods on the planet in the last 10 000 years. The largest of those is called the Thjorsahraun putting out an estimated 20 cubic kilometers of lava.

Photograph by Örn Óskarsson. Anybody who wishes to rent a cabin?

Rifting Fissure Eruption

When Katla, Bardarbunga or Grimsvötn has a major and sudden influx of magma from the hotspot, and the fissure swarm of the volcano in question suffers a rifting of the Eastern Icelandic Seismic Zone opening it up. Then what happens is a VEI-6 eruption at the central volcano, and a minimum of 10 cubic kilometers of lava erupts down a minimum of 100km fissure. It is the most destructive type of eruption likely to happen in the northern hemisphere.

The reason of them being that problematic is that it at the same time it releases a lot of ash into the atmosphere, about 100 times the amount from Eyjafjallajökull and also the fissure releases a lot of sulphuric gasses. This phenomenon is called dry fog, and was reported in most of northern Europe and the USA during the eruption of Laki in 1783.

The Laki eruption is the most deadly in European modern history due to the famine that followed. 1783 is also known as the year without summer.

Dead Zone activity of today

Image by IMO. Look at the line running up from Torfajökull/Myrdalsjökull, that is Veidivötn.

During the last 12 hours a series of small (1 to 1,8M) earthquakes happened inside the Dead Zone. They trend from Torfajökulls Landmannalaugar up along the Veidivötn fissure towards Skrokkalda.

What is remarkable that this phenomenon has never been recorded before.

At the same time there where harmonic tremoring in the SIL-station of Skrokkalda, Vatnsfell and also Snaebyli, shown here is the activity at Vatnsfell.

Image by IMO. Vatnsfell SIL-station showing harmonic tremor.

There has also been activity at the Dyngjufjöll, the principal SIL-station of the Bárdarbunga volcanic complex.

http://hraun.vedur.is/ja/oroi/dyn.gif

And here is a webcam of sorts for the Veidivötn area:

http://helgi.dk/?page_id=352

Caveat for the press

Please dear all, it is still far from any possible eruption in the area. At most this is a signal of what can come, nothing more.

CARL

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453 thoughts on “Activity in Iceland’s Dead Zone

  1. One thing that everyone needs to remember, is that tremor on the traces in Iceland may not be tremor. You have to keep an eye on the wind. Iceland gets storms pretty often, and usually has the “Icelandic Low” semipermanant atmospheric feature nearby. That thing is a storm magnet and accumulates many of the storm systems comming ouut of the US, Canada, and the Atlantic. I takes an accoustomed eye to read them correctly, a skill that don’t even have yet.

    • That is true. Funny thing is the winds in these areas have not been that bad. In fact there is another “pulse” happening right now and in that area east od Katla there should be little to no wind today.

    • On the SIL-plots it is normaly almost impossble to see the wind.
      So, one should always check the windspeed first on IMO page. It is rather good at windspeeds.
      Also there are anemometers at the Road council (or whatever the local name is that I have forgot).
      It is easier to spot it at higher resolution, but I have been fooled a couple of times when looking at the public SIL-plots.

      • I don’t know anything – but why not have one of those spinning wind gauges next to the SIL – and then display the real time wind speed on the same plot ?

          • All of it exists in English (almost), but often it is much better updated in the icelandic versions. Some of the speciality pages though are in icelandic only. But all the “normal” pages one might expect to find are there in english.

        • And one should always remember that although IMO is hellishly good at what they do, they do have rather limited resources due to Iceland being a very small country. What they do with what they have, and the mass of resources they get in percentage is stunning.

          Comparatively it would be like USGS getting about 10 billion dollars…

          • No disrespect intended, they do seem to be very very good 🙂

            I was just wondering really if they couldn’t record the windspeed on the same chart so someone looking at the tremors could more easily compare ‘oh increased tremor steady windspeed’ or that kind of thing.

            I was even vaguely thinking what you might be able to see if you produced the graph by ‘deducting windspeed from the tremor graph’ not that would be ‘correct’ to do so but it might give an indication where the tremor graph under heavy wind conditions really was/was not displaying significant info.

          • Yes, well at least it would be good to know if it is windy at the SIL-station. But for some reason they have opted out of it.
            It probably has to do with them trying to place the SILs in as noise free environments as possible, and the anemometers would therefore not be usefull for anything else more weatherrelated. And when on a shoestring budget I guess they have opted out of it.

        • Mainly… because it would show up in the traces.

          Seismo gear is already really sensitive, sticking a whirly-gig vibrator on it wouldn’t help it’s resolution any.,

    • There is no tremor at Mjoaskard.
      I wrote a short note on it yesterday in the comments.
      Those are microceisms that happen between 2 and 10 minutes apart. And because of every stapel on the plot (1 pixel wide) is 28m 48s in time, you get several microseisms in one stapel (stäbchen). That makes it look like tremor, but it is not. The actual tremor level on the plot is quite low really.

      These microseisms are a bit odd. I do not know if they are icequakes or popcorn. That is impossible to tell since I do not have depth.

      SNB also is having microceisms (most likely frost quakes), not harmonic tremoring.

      And for those wondering, yes, I do see the microceisms one at a time.

  2. Alaska / Kanaga
    The remote Kanaga stratovolcano in the Aleutian Islands might have begun erupting, the Alaska Volcano Observatory (AVO) reports.
    A possible ash cloud about 39 km (24 mi) NE of the volcano, likely from weak explosive activity, was detected on satellite imagery, and volcanic tremor was detected under the volcano from 15:23-15:27 UTC (6:23 AM AKST) on 18 February, followed by numerous small events for about an hour at Kanaga Volcano.
    AVO has placed the volcano at Aviation Color Code YELLOW. “This new unrest indicates a possibility for sudden explosions of ash to occur at any time, and ash clouds exceeding 20,000 feet above sea level may develop. If a large, explosive, ash-producing event occurs, the local seismic network, satellite ash alarms, infrasound, and volcanic lightning will alert AVO to the new activity.” (source Volcano Discovery)

    http://earthquake-report.com/2011/12/31/worldwide-volcano-news/

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