The Icelandic Hotspot Hypervolcano™ – Why old traps won’t erupt again

Photograph by Jeff Shea. A range of north Greenland shield volcanoes eroded by glacier ice so that they more remind of a range of strato-volcanoes.

Earlier today commenter Lucas Wilson asked me about volcanism in Greenland. So, I thought I should write a short piece on what once used to drive the volcanism there.

But let us start with what we today call the Icelandic hotspot. In here we have a tendency to talk about large volcanoes now and then, and sometimes about what is called “super volcanoes” in the media. But, the fact is that Iceland is both the largest volcanic structure on the planet, and also by far the oldest active one.

Let us start with largest. Iceland stands for between one third and half of all the magma on the planet during the last 250 million years. The rate of lava produced is fairly prodigious. Also, few know how long this has been going on. The answer is that it all started far before Iceland was born. Time for a history lesson.

Iceland was born as the Icelandic Hotspot moved close to the Mid Atlantic Rift; Iceland was born from the mid parts to the west and the east. This is as a function of the hotspot giving extra magma to the normal volcanism of the MAR, and thusly building the volcanic edifice known as Iceland as the MAR rifts apart.

Photograph by Ansgar Walk. Trap formation eroded by Glaciers, Ice age glaciation, and coastal erotion. Baffin Island.

Okay, now to the age thing. The Icelandic Hotspot is one of the really few surface expressions on the planet that is stationary. I know, the hotspot per see is not visible, but its effects are. So, as the continents and plates have fun surfing around bumping in to each other they slide over the poor hotspot.

A few tens of millions of years ago it was a part of the North American plate that slid over the Hotspot, and as that broke apart magma pushed through and created Greenland. As the now archipelago of Greenland slid away it lost its capacity to have eruptions pretty permanently.

Before that it was Newfoundland that popped up as it slid over the hotspot. And before that we had the same hotspot creating the largest Large Igneous Province on the planet, the North Arctic Igneous Province (NAIP). Before that Labrador and Baffin Island slid over the NAIP, and that put us at about 95 million years ago. And 130 million years ago it created the Alpha Ridge. Any  super volcano will have an inferiority complex to that eruption.

Before that and even further down in time it was known as the Siberian Traps, the largest on land eruption. And now we are back 250 million years in time. Before that things get a bit harder to track.

Photograph by Jxandreani, wikimedia commons. This is a part of the Putorana-Norilsk Deposit.

Here comes an interesting thing. What is today known as the Icelandic Hotspot has been conveying about the same amount of magma since the Siberian Traps. Give or take the eruptive rate has constantly been around 0,5 to 1,5 cubic kilometer per year since day one. And as we all know the average erupted material is only 1 in 20 of the magma that comes up. The rest stays as intrusions or inside magma chambers. So, on an average year the Icelandic Hotspot will loft up 20 cubic kilometers of material.

Now some of you will say something like “Hey dude, it never erupted continuously, so it can not be the same. And dude, the Siberian Traps erupted more material than Iceland”.

The reason for it not having erupted constantly is that it need either pressure enough to crack a continental plate, or the magma had to wait for a spot that was weakened that it could crack. The Siberian Trap was a momentous episode, but the largest separate eruption was “only” 3000 cubic kilometers of lava erupted (Norilsk Deposit). In the end the Siberian Traps is only standing for a slight elevation in erupted material even though a lot of magma had accumulated under the Eurasian plate before onset of eruption. Average erupted material during the Siberian Traps was only twice what Iceland is popping out on average.

The Siberian traps carved by a river into a kilometer high cliff.

We should also remember that eruptions happen in cycles. The Norilsk Deposit is probably a hundred million year event, or in other word, it would take on average 100 000 000 years in between every eruption of that size. It is estimated that it took about a hundred years to erupt that amount. So, on average 30 cubic kilometers per eruption year and that is not a nice thing to be around, but far from what it takes to produce a mass extinction.

We know that there are about 2 to 4 eruptions on the scale of above 10 cubic kilometers in Iceland today per every thousand years. They tend to happen on a 270 year cycle. We also know that every few thousand years we get them in the 30 to 50 cubic kilometers. Most likely those come in about 1000 year cycles, but in various places over Iceland, and on average over time.

About once every 10 000 years we get one upwards to a 100 cubic kilometers. I do not know of any eruption in Iceland significantly larger than that, and would be surprised if anyone finding one. The reason of course is that the MAR creates a fairly open passageway for the magma. Norilsk was happening due to the dense rock of the Eurasian plate storing up magma under it until it cracked, so the necessary magmatic pressure can most likely not build like that in Iceland.

So, now we know that old huge volcanoes cannot erupt again due to the magma-hose being disconnected as the plates slide away from the “gas-station”, and we also know how persistant the hotspot is.

Super volcanoes, well all is relative…

Bonus Riddle from Alan

Many of you might have missed that we tend to have volcanic and geologic riddles every friday in here. Lately we did not have that due to El Hierro taking center stage. But we do know that there are many that love them, so here is bonus riddle. Remember, it should end up in something rocky.

Huh! Last week, I went into a nice bakers – they only had this rock-cake!

CARL

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721 thoughts on “The Icelandic Hotspot Hypervolcano™ – Why old traps won’t erupt again

  1. Morning all!
    Hey, Renato (and everyone) please keep posting updates of volcanic activity on volcanocafe, as I use them for my special Journal that reports monthly volcanic activity: volcanismbulletin.org

    • I think it’s on the actual strain meter instrument/machine. They regularly do it on the Hekla strain meter but this is the first time I’ve seen it on Hella. Now it’s summer I guess the mechanics/scientists can get out in the field and check all their instruments.

  2. I’m very curious about where this new pattern of Etna’s activity will lead to.
    Tremor has been oscillating up and down and strombolian activity continues vigorously at the Bocca Nuova, and I think, as well, the NE crater is joining the party.
    Boris has been very laconic about it (an I give him total reason to do so). Volcanoes, even an “intimate” one, like Boris is to Etna, are unpredictable.

  3. Just been writing for the Bulletin (dreading putting it all together for the end of the month) and wondering what will become the 2012 Pliny?

    Nothing has really stood out this year, apart from the Zubair Group at the start of the year.

  4. While charged silence remains under El Hierro I created this rotating 3D video of all earthquakes. I colorcoded the azimuth from the IGN list which may give a hint on the focal mechanism (no Expert TM!).

    There is an intriguing pattern: while most earthquakes have azimuths of about 180 or 0 degrees, the swarm leading to Bob and the trunk of the current swarm seem to have approximately perpendicular orientations. I wonder if this observation could give a clue how the magma progressed, by delamination, melting,…

    The plot was made in Igor Pro and captured with CamStudio.

      • Was just picking up an earlier idea…
        GeoLurking says:
        July 12, 2012 at 00:16
        Yah.. poor man’s focal mechanism. Unsupported by any research or doctrine. Just the wild idea that the worst resolution would be along the line of the fault plane.>/i>
        So the plot is probably complete nonsense, but still naturally pretty in a way I thought.

      • Quakes do not occur at a single point. They happen along a fault face.

        Seismometers are not ultra precise locating devices… in fact, many things are not ultra precise, even GPS (especially GPS), all measuring equipment has some margin of error.

        When you allow for the error, you wind up with a small region or zone that you have a lot of confidence that the thing you are trying to locate, is inside of. You also have a lot of confidence that it is not outside of this zone. It could be a box, a square, a circle or an ellipse, depending on how your gear works and how your locating methods work.

        Seismometers only provide two pieces of information that can locate a quake. You have to work to get it though by comparing the signals with other seismometers. IF you have enough of them to compare, you can get three pieces of locating info.

        This data is bearing, distance and depth.

        If you plot the bearing cuts from the different stations, you wind up with an are where all the bearing lines cross… or at least try to. They will not be exact. Plot all of the intersections and it will make a shape similar to an ellipse.

        All ellipses have a major axis, and a minor axis. (long side and short side)

        The Azimuth that you see listed in boletin_hierro is the bearing of the long axis. Since there is no way to know which end of the ellipse is the “front”, they only give you the bearing from 0 to 180 degrees. anything more than that is redundant. (a 270° AZ is the same as a 090° AZ.)

        Hierro’s error ellipses tend to be aligned along a mostly N-S trend.

        • Thank you so much for the explanation, I will try to understand the implications in some quiet hour 🙂

    • Chryphia,
      Fascinating pattern, thank you. Just to check colour code: blue is 180degree up, red is downward??
      The second deep swarm is almost entirely blue. The first swarm was blue in north then changed towards red as it propagated south. Then close below this region the 2012 swarm started reddish, then spread west going blue.
      So the azimuth bears less relationship to a swarm (or time) than to position. I have difficulty fitting that to processes caused by three successive magma injections but to pre-exisiting structure. The almost complete lack of green (very little 90 degree horizontal azimuths) raises the question: how can magma spread horizontally kilometres without at least some horizontal strain? The country rock must be very weak horizontally with the eqs generated by compressive fracturing vertically. Or perhap something else underlies the pattern.

      • Worth noting the first swarm show clear demarcation between zones of dark blue and zones of yellow-red. There no purple effect from intermixing. At north end the blue ‘sphere’ seems to be enveloped by a ‘shell’ of red. And theres an almost total lack of greens or pale blue (azimuths around 7- to 120 are absent).

      • From what I understand so far from Geolurkings description red and blue would be a north-south line, not a vector. So whether the value ends up being 179 or 1 degree is chance.
        Pre-existing structure, I don´t know if there is any 3D tomography which this plot could be fitted into.
        Maybe it also has to do with how fast the magma progressed, the pre-Bob swarm and the recent swarm both spread very fast in contrast to the more stationary other swarms.
        Still ruminating…

  5. OMG – a man burst into a theater in Colorado during the midnight showing of the new Batman movie and killed 14 people and wounded 50 others from gunshot wounds and shrapnel. Some of these are critical. A baby of 3 months old was among the wounded. The shooter is in custody. My prayers go out to these families.

    • Yes, I’ve been following it on the news this morning. There are some very weird, strange, people in the world. I hope that all the injured recover.

      • on the face of it, he seems to have it all, educated, etc.must have a few screws loose somewhere, it is alwyas the quiet ones you have to watch

    • there have been smaller EQ on a regular basis since the 5.6 about a month ago, that whole area seems to be coming alive in the last couple of years

  6. OT: Does anyone have an idea if something is planned for the normal opening of the Sheepy Dalek Bar tonight?
    To celebrate the 50k comment?

  7. Hello Everybody!

    As you might have noticed I have been missing for a couple of day.
    Thing is that I will most likely be away quite a lot during the coming days.

    Even though I cannot concentrate on the blog right now for personal reasons, I know that it is in good hands untill I can. I will check in when I can.

    Kindest Regards
    Carl

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