Posted on by Jón Frímann

Are Esjufjöll volcano starting to inflate ?

I have been monitoring the GPS station at Grímsfjall volcano. After the earthquakes that took place in Esjufjöll volcano few weeks ago something interesting started to happen at that GPS station. It started to move in north direction.

Due to the location and lack of activity in Esjufjöll volcano there are almost none GPS stations around that volcano, and there are not many SIL station in this area. So getting insight into what is happening in Esjufjöll volcano is hard. But given the GPS station at Grímsfjall volcano it seems to that Esjufjöll volcano have started to inflate. It is hard to know exactly by how much at current time. But it appears to enough to have effect on the GPS station at Grímsfjall volcano.

This is given that Grímsfjall volcano it self is not having any inflation south of the GPS station on it’s own. At the moment it is hard to know what volcano is responsible for the northward movement. Only time is going to tell us the truth in that matter.

Grímsfjall volcano GPS data (automatic, Icelandic)

43 Replies to “Are Esjufjöll volcano starting to inflate ?”

  1. Hehe!
    Sneaking a new post again:)

    Noticed that movement. It started at the same time as some spiky tremorpatterns came at FAG. I think it is the closest station to Esjufjöll. It’s tremorpattern changed and has stayed in the changed pattern since the last quake swarm. Before that it looked a lot like Mokolar with a nice even pattern, but now it is more “energetic”, even though the average energy has just gone up by 25 percent. But the variations are much sharper in the shifts than before.

    1. You have to use this blog RSS feed. Then you are never going to miss a blog post or have them sneak up on you.

      http://icelandgeology.net/?feed=rss2

      The change you see on the SIL stations are mostly weather. But might also be related to Grímsfjall volcano and the changes that happened after the glacier flood that did come from it few weeks ago.

      1. Aha, RSS it will be.

        I have correlated Fagurhólsmýri against the weather and it is still showing significantly more energetic pattern-changes than before the last quake-swarm. But, the energy-levels are still minute. My point is just that something has changed, but exactly what is beyond me.
        FAG didn’t even react to the Jökulhlaup from Grimsvötn by the way.

  2. I have been reading up on the volcanos in Vatnajökull and done some calculations.
    The combined magma reservoir of the “unrestfull” volcanos Bardarbunga, Esjufjöll, Grimsvötn, Hamarinn, Kverkfjöll, Loki-Fögrufjöll and Öraefajökull exceds 500 cubik kilometres of magma (low estimate).
    They have all shown patterns of movement that indicate inflation, quake swarms and unusual tremor-patterns. The 2 most active is of course Bardarbunga and Grimsvötn, both of those might from a geological time-frame be said to be a hairsbreath away from erupting.
    Problem here is that with all of these volcanos simultaniously showing unrest and inflation increases systematic pressure, ie. if one erupts the likelihood is high that more than one will erupt.
    It is also indicative that all of them are showing signs of inflation and/or new magma intrusion in their respective magma-reservoirs that pressure is increasing from deep down under the entire area, and that a very large mobile magma “glob” is being pushed upwards under the entire Vatnajökull area. That glob if it exists would than be the “super-source” of them all. It also seems, which is a bit strange, that the “glob” if it exists have been moving from west to east during the last ten to fifteen years (extrapolated from first sign of increased unrest).
    If this is correct then we will probably within a short (geologically speaking) time frame see a larger activity in the area with numerous or simultaneous eruptions with up to 10 percent of the total content of magma reservoirs in the afflicted volcanos being released, all depending on the amound of water and gas in the various magmas involved, and that is as long as no new magma is pushed up from the glob. Ie, we are talking about 10 to 50 cubic kilometres of magma or more being released over time. With “time” I mean the time from beginning to end, and that time might vary a lot. If it takes fifty to a hundred years we would be fine. If it all goes in 2 years we are in trouble, think Lákagígar or worse here.

    Oh yes, nothing makes me so doomsdayish as bean-stew and a hot date with my laundry-basket on a saturday evening… 🙂

  3. I’ve been fighting software installs and what not… getting pillaged by forum software and fiddling around with making a pizza and doing some back of the spreadsheet calculations.

    Taking SKRO’s E and N graphs, and GFUM’s E and N graphs, cutting out that portion that will fit smoothly into Dplot and digitizing the numbers (cuz is easier to have the program do it rather than by hand), I get the following.

    Since 10/19/2010:

    GFUM is showing a speed of 210 mm/yr along a bearing of 354°.
    SKRO is showing a speed of 8 mm/yr along a bearing of 291°.

    And again I emphasize.. this is since 10/19/2010. Real short term. SKRO is North of the plate boundary… GFUM is not. That looks about normal for SKRO… but GFUM… well Jón Frímann saw it first, so it’s his puppy. It’s also in his back yard.

    I just plot stuff. (I also used to do navigational solutions… but that was on a ship a long time ago)

    1. Neat, real neat:)

      I will complement it with the Up movment projected from the data during 15 – 20 / 10. Margin of error calculated with Monte-Carlo game theory modelling. The numbers are high on the margin of errors since the period is so short.
      GFUM = 532,3mm per year. Margin of error 30 percent
      SKRO = 76mm per year. Margin of error 65 percent

      The up-movement of GFUM is so large that the prognostication is statistically vallid for any number below the margin of error. (Please for the love of warm socks in the winter, remember that this is just a mat-stat modell and not future reallity. The mountain could stop moving tomorrow, or sink for that matter.)
      What I am saying is that if this impossibly fast movement continues (and it won’t) the mountain will rise with half a metre over a year.

      1. Question:
        How in the name of all unholy goose-feathers can we see these numbers without seeing other signs? The energy equivalent is high, very high. It equals a mag 4 per five days you know. Either the crust is really plyable there or something is wrong. And we should see something on the tremor plot. Movement like that should send out a continous chock-wave rumble.
        I guess we will have quakearoo in a couple of days if the numbers are correct and continue.

      1. GFUM Up-prognosticated for long-time series.
        50mm annualy since 2006
        120mm yearly (calculated from mid april to today).
        240mm yearly (calculated from last month to today).
        This figures are all statistically proven with an error-margin of only ten percent for the last-month number.
        We are actually seeing an accelerating inflation phase happening right infront of our eyes, and it is mathematically vallid.

        The Ice-removal is not a factor here since it acts up as an out.layer and is calculated away.

      2. Let’s also remember that the last eruption at Grimsjöll pretty much didn’t lower the system in any significant numer. If I remember correctly it had risen with 250mm at the time of last eruption and fell just a few mm (if memory serves) during the eruption, so we are looking at a mountain that has risen half a metre in just over a decade, and we would need a sheeps gut to calculate how high it has actually risen since the last major eruption.

      4. If im not mistake the GPS is not located on a patch of ice. For the data to transmit real and reliable figures it is placed on a patch of rock..Otherwise the reason to have a gps station there would be mute. And if it is as you say that it was due to glacier retreat it would indicate this in the summer half of the year not now when it is below freezing constantly and the glacier builds..

      5. Daniel is right with this. This station is placed on the only piece of solid rock on this glacier, basically the top of a mountain which is burried under the ice.

      6. The glacial uplift is about 10mm annualy so we can disregard that.
        Most of that is residual uplift from the ice-age, but som is actual crustal rebound due to the diminishment of the glacier. But it is in this circumstance pretty much superflous.

        The 50mm annualy is by the way probably the “normal” uplift of iceland due to hotspot inflation. Iceland is after all “permanently” uplifted with a whopping 80 metres.

    3. Carl you stated something that could be the answer to the non noisy state of affairs…

      “Either the crust is really pliable there or something is wrong”

      That pliable thing would mean that Grímsvötn, Bárðarbunga, Hamarrin, Esjufjöll, Tórðarhyrna and the rest of the nefarious crew are sitting on a pile of mush.

      That might not turn out well.

      CAVEAT: I am not a geologist, don’t quote me.

      1. Those volcanoes are on top of ~40 km thick crust. So no mush there. It appears that a fissure events (big ones) happens every 300 to 700 years apart. I based this on the data that I have been reading up on for a few years now. Where and when they happen is impossible to say.

        Here are two articles on that.

        http://www.open2.net/timewatch/icelandic_eruptions.html

        http://news.bbc.co.uk/2/hi/8624791.stm

        http://tinyurl.com/29becqj (might be free to some people)

        http://en.wikipedia.org/wiki/Laki

      2. Yes, I am aware of the 40 km of crust.

        That’s why I noted the Bouguer anomaly map. To get an idea of what area might account for the uplift/northward march and present no quakes.

        The map seems to follow the contours of the Moho that I’ve seen in other papers, and could present a nice mental picture of what the bottom of that chunk of crust is like. Esssentially showing the “pits” in the bottom of it that have been erroded away by the hot-spot.

      3. Jón, my point is that the nefarious bunch is not right ontop of any mush.
        My hypothesis is that it is a glob of mush moving in rather rapidly under the 40km crust. And that globb has now gotten all the way down to Esjufjöll. So now pretty much all of those volcanos are in a rapid inflation phase.
        And if that is true we might get a fissure event, but remember that it does not need be one, it could instead in this instance be a serie of higher frequence larger than normal eruption spanning a hundred years or more. Or it might be simultaneous eruptions from several volcanos (data seems to make that a bit more likely). Or it might be all of the above and then we would be in Crapotkin to say the least.

      4. So… I sit here wondering about how to get a better grip on what things are like under the glacier/icecap.

        Gudmundsson and Högnadóttir had a paper in 2006 “Volcanic systems and calderas in the Vatnaj¨okull region, central Iceland: Constraints on crustal structure from gravity data” that has a really nice Bouguer anomaly map as figure 3 on page 159 of Journal of Geodynamics 43 (2007).

        It gives you a very nice idea of the structure underneath the problem children of Vatnajökull.

        Using it as a base, and dropping the Lat and Lon of GFUM and SKRO referenced to the images coordinates, and then throwin in two vectors of about the right relative length you get this:

        http://i55.tinypic.com/33u90zn.png

        And now… since I can’t really explain it, I drew it.

        Same background, but a more detailed view, this time with the quakes from 1 July placed on the chart. Note the arc of quakes (which I yammered about a few weeks ago) that tracks down a variation in the anomaly. I think that magma was either flowing into or out of the Grímsvötn area to/from Hamarinn.

        http://i53.tinypic.com/ehne6f.png

        But it still doesn’t explain the monster uplift that’s going on. From the detail image you can see that most of the quakes have occured North and West of GFUM.

        Beats me.

      5. First comment, remember that the heavy depression in the middle is an offset from average Icelandic level (80 metre above earth-norm) so it is still 40 metres above earth-norm.
        This depression is of course caused by the weight of the glacier “pressing back” against the uplift.

      6. About the quake-location:
        I would here insert that the crust seems to be plyable here and easily stretches. But that doesnt imply that it is as easily compressed. I would say that it is compression quakes as the crust is pressed together. But this is beyond my line of specialisation. And it would be insanly hard to calculate even if one had all the necessary data… *sulking*

  4. Well, the Icelandic mantle plume is giving a new burp, right? Ok, times & conditions might get interesting in the future… Nice post, Jon!

    1. Signal timing error caused by snow or ice on top of the flat antenna. Apparently, the stuff on top acts the same as lifting the antenna.

      1. Yes, it delays the signal to the receiver (radio signal travels inside ice slower.)

      2. That ice was build up from moist sea-air hitting the antenna, a phenomenon that is not unusual. But that ice is now removed and the climate should now prevent that.

  6. Hey guys, if you look at the long-term graph that Jon posted here, you will see that Grimsvotn has a spike of 5cm up every winter which is probably due to snow. However, you will see a long-term increase of about another 5cm every year. This happens also in SKRO and SAUD close to Bardarbunga and Kverfjoll volcano. This might mean that a somewhat large fissure eruption would be on the preparing there. But it’s impossible to tell how much time this will take. And we don’t know which volcano is responsible for this activity. Could be Bardarbunga, Grimsvotn, Esjufjoll. I think because HOFN does not show a big rise, I would say that magma is moving close to Bardarbunga and Grimsvotn, but because of the lack of earthquakes we are still not close to an eruption.
    It could be also that we will see smaller eruptions and still see the continuation of this GPS rise until the next large eruption.

  7. The Bardarbunga system has erupted so far for the last time in the 18th century. After that Grimsvötn has been the “only” active volcano under Vatnajökull (see http://www.raunvis.hi.is/~alexandr/glaciorisk/jokulhlaup/subglaVolc/vatna/index.html ).

    Well, it can be thus expected, that the other Vatna volcanoes show signs of new activity some day. In particular I find it interesting, that the Grimsvötn eruption in 2004 did not cause any deflation. So, it must have only released locally some overpressure, leaving the overall situation intact, waiting for the major one…

  9. Its not true that since the 18th century Grimsvotn was the only active volcano.

    Bardarbunga erupted in 1910, but that was a small eruption, about VEI2
    After that there was some activity in recent decades, but everything under the glacier.
    http://www.volcano.si.edu/world/volcano.cfm?vnum=1703-03=&volpage=erupt
    The eruption of 1996 was also located close to the Bardarbunda system.
    Last bigger eruptions were in 1717 (VEI3) and Veidivotn VEI6 eruption in 1477.

    Kverkfjoll erupted in 1929 and 1968, about VEI1
    Another small eruption in 1729.

    Esjufjoll possibly had a subglacial eruption in 1927, there was a large glacial flood at that time. No other known historical eruptions.

  10. If Esjufjöll would be inflating, wouldn’t Grimsfjall also be moving west (or less east)? Which is not the case.

    1. No, it would not if it also was inflating. The only heads or tails I can make of it is that right now Esjufjöll, Hamarinn and Grimsvötn is inflating, that at least works with the actual movement when calculating the trajectories. Esjufjöll is pushing the uplift towards Bardarbunga and is being “trajectoried” by Hamarinn. And that Kverkfjöll is not inflating since it would then be pretty much a standstill at GFUM. But here I would like to point out that we would really need more GPS-stations closer to Esjufjöll and one ontop of Bardarbunga to be sure…

      2. Esjufjöll might have a effect on Grímsfjall. But not Bárðarbunga volcano. But Bárðarbunga volcano can and has had a effect on Grímsfjall volcano in the past. For instance it almost started a eruption in Grímsfjall volcano in March this year (2010). But for some reason it stopped in its tracks.

      3. I’ve always suspected that it halted due to no large enough quake to shake loose enough gas out of the magma to create a break-through.

        I would say that the material ontop of the magma-reservoirs is so plyable that it will not break untill a large enough quake disturbs the magma sufficiently to make the gas go into an excited state. And the longer that quakes take to manifest the more gas is trapped due to almost constant inflation and magma intrusion, and the worse the eruption gets.

        But, I am no volcanologist.

      4. It is the magma that creates the earthquakes in this case. There is not a lot of tectonic activity around Grímsfjall volcano far as I know of. There is some. But nothing that is able to start a eruption in Grímsfjall volcano.

        But I might be wrong in the terms of interaction on that field.

      5. With the movement around Grimsfjöll you can probably also get quakes from the pressure itself.
        Lets say that you have a part of the crust is a bit harder that the more plyable material, if that fractures due to pent up strain it could probably produce a large enough quake, depending on the size of the “crack”.

  11. Jon, I was wondering, the Vestmannaeyjar-volcanic system has been inactive for only 30 years, which is rather small in geological terms. Why are there second to none earthquakes in this system? I know it’s dormant for now, but even at Langjokull and other long-dormant volcanic systems we see a small quake once in a while. Is Vestmannaeyjar the Hekla-type of volcano?

    1. It appears that Vestmannaeyjar volcano system is quiet like the Hekla volcano. I do believe that this is the case for many volcanoes in Iceland. They are quiet until they get ready to start erupting.

      But there are volcanoes that are not quiet, but make a lot of noise with earthquakes.

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