Rapid inflation at Grimsvötn

Grimsvötn 2011 eruption. Photographed by Jóhann Ingi Jónsson.

Grimsvötn 2011 eruption. Photographed by Jóhann Ingi Jónsson.

I have been tracking what is happening at Grimsvötn since the last eruption and the entire hubbub at Bárðarbunga. If you look at the GFUM GPS station you can see the slow and steady inflation speeding up a bit before the intrusion into the Bárðarbunga system started.

In the days prior to the intrusion the speed of inflation increased a bit and the normal southward motion increased too. As the intrusion hit there was a rapid south movement which was to be expected since the entire area was affected by the rapid intrusion into Bárðarbunga.

Later the southward motion changed into a northward motion as the magma started to rapidly move out of Bárðarbunga and the inflation continued at the same slightly increased speed. This was a bit unexpected and I started to speculate that there might be magma arriving into the volcano due south of Grimsvötn called Háabunga.

Map showing the location of many, but not all of the known volcanoes under Vatnajökull.

Map showing the location of many, but not all of the known volcanoes under Vatnajökull.

It has not until now been known if Háabunga has an independent magma reservoir even if it has been suspected. Not much is known about the eruptive behavior of this volcano, but it is known to have erupted during the time after Icelandic settlement. It was though not known if it was due to fissure eruptions from the central magma reservoir under Grimsvötn or from an independent magma reservoir.

If the northward motion had been entirely due to deflation of Bárðarbunga there would have been a diminished rate of upward motion showing at GFUM, or even downwards motion. Instead the inflation continued unabated, a sign that not all was right.

And due to it being upward motion the source of the inflation had to be south of the GPS station. But, so far it was a bit speculative and also the amount of inflation was rather insignificant for such a large volcanic system.

Image from University of Iceland and Sigrun Hreinsdottir.

Image from University of Iceland and Sigrun Hreinsdottir.

Yesterday the northward and upwards motion magnified a lot. In one day the GPS has moved 4 centimeters to the north and 3 centimeters up. This point towards a rapid intrusion occurring about 5 kilometers south of the GFUM station and due to the lack of earthquakes the intrusion must be happening into a pre-existing well evolved magma reservoir.

This intrusion is not yet visible at other close stations, but one should remember that there is a mechanical delay before the movement shows up there. Somewhere tomorrow we should see Hamarinn moving westwards and slightly up. And not until we have data from several stations we will be able to estimate the amount of intrusion that is happening. If it affects several far out it is a large one, if just a couple close by it is small.

So far I will go for a small intrusion due to the lack of earthquakes. Someone asked if this might be magma being squeezed out of Grimsvötn due to pressure from Bárðarbunga, but that would not show any net upwards motion, if anything it would create a motion downwards as we currently see at Bárðarbunga.

Now, will this cause an eruption?

Image from University of Iceland and Sigrun Hreinsdottir.

Image from University of Iceland and Sigrun Hreinsdottir.

It is hard to say for any volcanic system that has unknown characteristics. I can though say this, before anything will happen we would need to start to see earthquakes that slowly or rapidly transform into a large scale earthquake swarm like we have seen at Bárðarbunga. After that we would see harmonic tremor starting as gas was released as the magma moved upwards.

My personal guess is that we would see an explosive onset and that it after that would transform into a Gjálp style ice lava interaction eruption with small scale explosivity. This is though an extrapolation, but I think it has merit.


Reminder:  There are still a few riddles left! (Check the link at the top of the page!)  

1,124 thoughts on “Rapid inflation at Grimsvötn

  1. Screen shot 3 mins ago.
    I can’t see any clouds that would suggest any sort of volcanic activity over Bardy. There are however some small lenticular clouds. These are usually formed when stable moist air flows over mountains or even tall buildings.
    Looking at Jokulsarlon there seems to be a fog so stable moist air. If that is feeding up through the valley from the South and meets the “soild wall” of the super- heated air from the eruption then it’s possible the lenticular clouds and other odd cloud formations could be created.
    I too have seen more billowing mushroom shaped clouds over towards Bardy. I am not ruling out no activity BUT I do think that if there is super-heated air from an eruption or even a small “seepage” of volcanic gasses then the cloud will be very, very noticeably different and will not be mistaken for anything else.
    Bear in mind that the temperature over the glacier is very cold . If hot air hits that there will be a dramatic cloud formation.
    Not an expert in clouds, weather or volcanology and certainly not pooh pooing other people’s observations . Anything is possible in this event and nothing seems to be behaving in expected manners. 😀

     photo 1-jpeg_zpsb5ce0cda.jpg

    • What I saw was lower, darker, it happened pretty fast, and it all happened much more on the right, about 1 cm to the left from the left edge of the lava cloud, that area around the horizon I think. Is that Bardabunga? Part of it could even have been obscured by the coud in the foreground sometimes. There were some static images of it on the last comment page showing some frozen states of it, but one really should see it moving to judge it. Nearby real clouds looked and behaved differently. The activity then after a while seemed to stop/not happen again, so after a while closed the webcam video. It would be good to have this minutes as a video sequence or GIF, so other people could look at it. While seeing it I was convinced that it has its source on the ground and moves and expands upwards and to the right, and is result of some activity on the ground there, but that of course would not exclude some kind of “normal” cloud that is the result of air humidity/condensation. It was also difficut to make out the horizon, could also have happened in the sky. While it happened, though, to me it looked comparable to the other lava cloud in its way of moving and expanding, only not a as a steady flow, but some single clouds – pause – another one – pause, sometimes 2-3 in nearby places. Did my eyes deceive me or my imagination and interpretation took me too far? Possible. I “expected” to see volcano activity, and was not neutrally biased.

      • I too saw piling dark clouds that dissipated quickly in that area. They could well have been from some emission which rapidly stopped. I am no expert and am probably very wrong, but I cannot think that any form of volcanic emissions could happen and stop so quickly. I always imagined that here would be a definite “long term” plume or cloud formation.Please, if there are any experts could you help out with this please?

        • I am probably even less an expert, but I imagined that before a huge event like a caldera collapse happens, there might already be smaller events happening, like big chunks of ice breaking from the glacier after an earthquake and then falling somewhere where it is hot, or some molten ice/water now reaching some lava/magma and then causing some explosions, but a smaller amount of water, so not (yet?) the “big thing”. I also would imagine a process in that scale to happen gradually somehow, not suddenly a 10-second affair. There should be some warning signs before, and I thought that this was maybe something like that, in connection with rising tremors and the earthquake that happened right before. But now after reading other comments I am already nearly convinced that it all was more like a Fata Morgana and “normal”. Nearly convinced, 90%.

  2. Oke since it’s that time again.. obviously this is a mushroom cloud and this picture is photoshopped but if bardy go’s you will know!

  3. I’ve been looking at the Bardar 1 webcam for a while I and can see nothing over Bardarbunga except for ordinary skies. There is foreground cloud activity condensing from the left and feeding into the Holuhraun eruption cloud, probably generated by circulating air over the lava. Most of Bardarbunga is hidden behind Holuhraun’s eruption cloud anyway so any activity there is hidden. I do not believe there is any activity in the air over Bardarbunga.

  4. I have a (very simplified) theory of this eruption, ignoring some other variables. If it stays this stable (which it seems to be for now), this is how i see it :

    Imagine, you have two big cylindrical containers, connected by a long and very narrow tube at each bottoms. For now this tube is blocked. One container, 1 meter across, represents BB. It is placed on a table, and filled with water. On top of that water lies a wooden plate about 10 centimetes thick, exactly fitting the container. The other, representing our shiny new shield volcano, about 20 cm, is placed on another table, a bit lower than the other. It is empty. Now remove the blockage in the tube.

    Water will flow from BB to Irpsit. However, since the wooden plate doesn’t let pretty much any air through, it won’t flow that fast, creating a pressure system. The water pressure, an up-force, and the weight of the plate, a down-force. They were in balance just before the ‘eruption’. Now the up-pressure from the water is slowly subsiding because there is less water to press. It will create a netto-downforce. When the downforce is big enough to overcome the sliding force between the edge of the plate and the container, then it will lower up to a point where there is a new balance in forces. i.e., it will hiccuply lower in the container.

    The eruption will continue until the water level in Irpsit has reached a level where there cannot be created a big enough netto-downforce to overcome the sliding force of the plate, thus creating a permanent balance.

    • nice idea – dunno if it’s correct but as long as the lid doesn’t get jammed/break that seems to make some sense 🙂 obviously ignoring magma input from outside your experiment 🙂

    • {joy jumping, ecstatic} I can’t wait to take a close look at this. What is the relationship between the EQs at the caldera, subsidence/inflation, increase/decrease in tremor? Which comes first, the chicken or the egg? Then, when does the new eruption increase/decrease? Before/after subsidence/inflation at Barda? How large a quake before significant measurable movement? Is rate of movement incr/decr? I love this! We’re able to “see” (GPS) and “hear/feel” (tremor graph) the action at the same time. Thanks for the new toy, Mopsy!

      • Yes, yes, putting it together means there’s all sorts of things to look for! Is there a pattern or is it a random correlation? The Bárðarbunga GPS is published with only 36 hours showing but I’m hoping to build up a picture over 10 days at least. I like toys like this too and delighted to share. 🙂

  5. I have a question about the topography of the area. The peaks of the caldera rim rise up to 1850 m above sea level, the bottom of the caldera itself drops down to about 700 m and the glacier covers all of it up to 2009 m above sea level, correct?

    Second question is about the calculated depth of earthquakes, is this below sea level as logic would suggest? I am a rookie reading with great interest here the the ongoing discussions.

    Thank you for your answers. The contributing members here are a great source of information as it happens. This is a fantastic blog!

    • Good point. no clue what depth it actually means. could be related to the closed station or just a general depth according to see level..

      • The depth of an earthquake normally means from the surface, where the surface waves are generated. That would be the rocky surface, not the icy surface. If IMO uses this system, zero depth is at 900meter below the top of the glacier.

  6. Pingback: Watch “Bárðarbunga volcano – livestream” on YouTube | the WeatherAction News Blog

  7. Greetings from Kansas City, USA. I’ve been lurking for several days and truly enjoy this blog and participants’ commentary.

    • Well, the drop at about 1400z was the quake. It then briefly went back up, then dropped again at about 1650z. Don’t have any idea why it went back up, then went back down without a quake, unless it is floating on the magma chamber? There was a quake over at the fissure of magnitude 2.0 at depth 10.2km about an hour after the big quake at the caldera.

    • If it was actually moving like that (snap reversing a 1 foot drop from a 5.3 quake) it would be time for Icelanders to beat feet to bomb shelters.

      • well yeah the rise made me make say that comment about expecting a follow up quake but so far no significant quake all i could see on Borg was one tiny spike ak neglectable i guess…

      • What if there is water between the ice and the bottom of the caldera? A quake causes the GPS to lower and then movement of water adjusts it back up?

  8. Although it is not Friday, I declare the Sheepy Dalek open just long enough for me to post this awesome picture of the Elder Dragon Spica. Be afraid, be very afraid…

    Dalek closed again. 😀


    This is Grimsvotn 2011. This is placed here so that everyone has a good point of reference as to what a Vatnajökull volcano looks like when it does go off.

    As you can see, there is very little room for ambiguity when it’s actually showtime.

  10. @Children:

    Listen up and listen carefully…
    An eruption at a large central Iceandic volcano does not start with a small little fluffy cloud.
    During Grimsvötn 2011 one nuclear bomb equivalent of energy was released EVERY SECOND. So forget puffy fluffy clouds. Think a horking large atomic mushroom going up.
    Here is a timelapse taken as the Grimsvötn 2011 eruption started. Now, ponder your fluffy clouds…

    Image and video hosting by TinyPic

  11. Don’t know if anyone has covered this here yet, but Jon over at his site just wrote:

    “There is no rapid inflation taking place in Grímsfjall volcano. GPS signal got distorted by snow or ice on the GPS antenna.” ….

    • Thank you for noting this Tor. It was commented on early this morning. 🙂
      Diana Barnes September 14, 2014 at 08:11

      Doesn’t it take ages to catch up with the latest news! I spend all my time now just reading all the comments since my last visit.
      We have so many people here now . This is good though 🙂

  12. Sig Bárðarbunga – Flight Tracker September 13, 2014

    Sun, 09/14/2014 – 13:33 – rosa
    We were given a plane Isavia, TF-FMS, the measurement flights over Bárðarbunga, Dyngjujökul and lava eruption site in the pocket yesterday afternoon (September 13). Sunk in a box Bárðarbunga was mapped in the same way as the 5th and 8th of September. The measurement yesterday shows that the greatest himself is now 23 feet metres about 1 km northeast of GPS monitoring stations established for Thursday. Attached format shows featuring altitude.

    Dimensions sigskálarinnar in Bárðarbunga is now about half cubic kilometers. Since the GPS station was installed, it has sunk approximately half a meter a day. It is slightly slower than average themselves from metabolised record (about 80 cm / day).

    completion of the mapping sunk regularly in the near future to keep up with the changes.


    DragonEdit: correcting Giggle into proper measurements (note: Giggle translates metres into feet and sometimes km into miles -> please, pay attention when copying translations into comments) /Dragoness

  13. The GPS measurements are very high resolution and stable. So stable that land tides should be visible, which even at Iceland’s latitude should be a few cm. But they don’t show up. Is it adjusted for, or are the satellites affected by the tides in a similar fashion cancelling out the effect?

  14. Sorry…I should have read first..so it is the sun? Thank you dear Dragons, for you amazing patience with those of us still learning…I know it must be frustrating to keep explain and repeating things! But I am so grateful for that * gives dragongs hugs n nuzzles*

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