Bardarbunga Update 20140903

 

Holuhraun eruption looking north from Dyngjujökull (Photograph by Einar Gudmann)

Holuhraun eruption looking north from Dyngjujökull (Photograph by Einar Gudmann)

Since the appropriate Icelandic authorities have today publicly mentioned the possibility of a large, acidic and explosive eruption at Bardarbunga, we now feel free to inform you that this possibility has been discussed by the Dragons, behind closed doors, for well over a week. The key information comes from this official IMO graphic:

The first premise is that earthquakes do not occur in molten rock. Nor do they form a clearly visible ring shape such as the above except under one circumstance – they do so around a body of liquid, in this case magma. A conservative estimate places the size of this body of magma at 8 km diameter, height unknown but most likely on the order of 3 – 6 km, depth also unknown but relatively shallow. Using simple geometry, 4 x Pi x r3 / 3 yields a volume of ~250 cubic kilometres for a sphere, but for our flattened body something on the order of 125 – 140 cu km.

Image by the Icelandic Met Office showing the "beach-balls" of the likely ring-faulting.

Base image by the Icelandic Met Office showing the “beach-balls” of the likely ring-faulting, compiled by Stephen Hicks  @seismo_steve

The important question is not how much magma there is but rather how much of this magma is eruptible. The answer must be “not that large a fraction” as otherwise, Bardarbunga would most likely already have exploded. At this stage a guess would be no more than perhaps 10% or some 10 – 15 km3. Also, in almost all eruptions on land, perhaps no more than <40% of the eruptible magma actually erupts. That still leaves us with a potential eruption of several, possibly as many as 5 km3.

Another hugely important factor is the content of volcanic gases, above all humble H2O as this is what determines how explosive the eruptible magma is. Again, we most likely have a favourable situation. To judge from the magma erupting at Holuhraun, the content of SO2 is exceptionally high at as much as a cubic metre per ton magma. But the magma does not contain much water at all, hence the magma within Bardarbunga most likely does not as well. Any explosive eruption at Bardarbunga would probably not be highly explosive on its own.

But there is one exacerbating factor and that is the presence of almost unlimited amounts of water in the shape of the Vatnajökull glacier. If it finds its way into this magma reservoir should an initial explosive eruption remove the roof or lid off the magma chamber, it will result in more and very large hydromagmatic explosions to follow after an initial eruption. Whether we will actually see such an eruption is highly uncertain, but if we do, there is little chance of it being larger than, at most, Pinatubo in 1991 – in spite of the staggering numbers involved.

While we regret that we did not make these very interesting speculations available ten or more days ago, we hope our readers will accept and sympathise with our reasons for not doing so. Now that the appropriate Icelandic authorities have, so to speak, “let the cat out of the bag”, the reasons behind this voluntary restraint on our part are no longer valid.

HENRIK

IMPORTANT NOTICE:
Only the IMO and the Allmannavarnir can issue volcanic warnings and only London VAAC can issue Flight Warnings.

WARNING:
We know a few wish to go there right now.
But, remember to stay on the where the wind is not blowing, this is a very gassy eruption high in SO2. Even one breath of the exhaust would kill you.

Editor in Chiefs note

This article is obviously an extemporization upon one possible scenario. It is not a representation of the most likely scenario. With that being said, we have tracked the ring encirclement of what is now deemed to be a shallow magma chamber that was not previously known to exist. We will at all times take us the right to write and publish articles upon scenarios. These articles will always be based on fact and science as it is understood today. Our view and our articles might shift focus depending on the interest of the individual writer and the current level of knowledge.

But rest assured that any scenario we publish is based on data at hand and on scientific explanations of it. We at Volcanocafé think that we have proven this time and again. After all, that is why we chose to write about the area in such detail months prior to the eruption. We did though not write about what we thought was an upcoming eruption until the last possible hour since we awaited for IMO to publish something. In the end I wrote and published the “something is going on” article a few hours prior to eruption without IMO giving a heads up. But before that the discussion had been going for a couple of weeks about it.

In the end we where the first to see it coming, we were the first to write that it would most likely cause an eruption, and we also published articles on what we are seeing currently prior to it happening. In light of that we now feel that the time has come to openly say that there is a small chance that a larger explosive eruption could occur at Bárdarbunga in light of new knowledge. In this case we awaited the IMO and the Icelandic University to lift the lid first.

We do not do scaremongering, we do science and scientific debate.

CARL

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1,549 thoughts on “Bardarbunga Update 20140903

  1. Apols oif already posted: image by EUMETSAT’s Metop-B polar orbiting satellite at 11:52 (UTC) 5 September 2014.

    Bardabunga Friday

  2. Any estimate of how far across that cauldron is? Doesn’t look very big but could be perspective. Also I think the latest mag3.2 could be right in that spot:

    Friday 05.09.2014 14:31:44 64.785 -16.909 7.2 km 3.2 99.0 14.2 km E of Kistufell

  3. So, if the eruption melts a bit of Dyngjujökull and the flood comes down over it, it’s essentially giving itself a bath? 🙂

    • Hi, Princess! Am just waking up! Was up awake ’til all hours watching this thing. Has anything happened since the two new fissures opened? Could you brief me on the current situation? If I try to read all the comments, I never catch up.

      • Good morning SoCalGal! Umm, let’s see…

        – there’s a depression in the glacier that’s been deepening over the past two or so days just 6 km in from the edge of the glacier *and right over where the crack is believed to be*, which is very concerning

        – a larger area of ground around the fissures is yet again restricted today (no journos or scientists allowed)

        I think that’s about it.

  4. That amazing Vimeo video from the helicopter above reminds me: yesterday Carl promised a treat from Islander today. Did I miss it, or is it still to come? I’m hoping for another airborne goody!

  5. Sorry for a stupid question but at some point I have read that the intrusion was around 1.5meters wide and a depth of around 17km.
    Looking at the graphic posted by princessfrito above how has the fissure opened up so far from the intrusion? A very rough calculation is around 2-3 km from the tip.

    Is the position of the intrusion known in detail or has the intrusion it widened as it became stalled?

  6. Can anyone help please ?- from the cauldron story http://www.ruv.is/frett/cauldron-spotted-in-dyngjujokull-glacier.

    “”The new eruption seen this morning in Holuhraun is in the small rift valley (graben) which has been forming due to the magma intrusion beneath,” says Dr. Sigmundsson.”

    By “the small rift valley” is he referring to the crack/fissure we’ve seen on Lara Omarsdottirs twitter feed, and which I can see might arise from a magma intrusion (dyke?) forcing the ground above it to split ? Or something larger ?

    I thought a graben was when the land between two faults subsides/drops, but that surely doesn’t match what’s happening here. What’s the mechanics of this graben formation ?

    Forgive my ignorance – total geology newbie, just fascinated by vulcanism since my first visit last summer (lay in the river at Reykjadalur and fall in love with active landscapes!).

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