The eruption in Grímsvötn / Grímsfjall volcano most likely not over

Here is a interesting paradox. While the eruption it self has currently stopped in Grímsfjall volcano. The tremor chart around Grímsfjall volcano is still acting like there is a eruption ongoing. I do not know why this is like this. But because of that I don’t think that geologist that monitor Grímsvötn eruption in Iceland are not ready to call off this eruption at current time. At least that is what the news did say at 12:20 UTC on Rúv.

They are also issuing warning to people not going to close to the volcano. As explosions due happen and they can throw up rocks that weight up to 1 ton. If anyone gets hit by that rock, that person does not have to worry about what happens next. The save distance for viewing the crater is estimated to be 2 km or more.

I have no idea what happens next. But I am guessing that this eruption might resume soon and without an any warning at all.

The tremor plot at 15:00 UTC. Pictures are from Icelandic Met Office.

This pattern of tremor is interesting. I am yet unsure what it means. But my guess is that this eruption is not over. Even if it has just stopped for now. I normally consider eruption over when the tremor has gone back into background noise (wind, ice, ocean etc..). That has not yet happened with Grímsfjall volcano eruption at this moment.

Update 1: Here is an tremor plot that Icelandic Met Office has released. The article where this picture is from Icelandic Met Office can be read here, it is in english.

Click on the picture for full size. I must point out that this picture is big. Copyright of this picture belongs to Icelandic Met Office.

Blog post updated at 20:46 UTC.

181 Replies to “The eruption in Grímsvötn / Grímsfjall volcano most likely not over”

  1. Thanks thanks thanks,
    in times like these its great to have someone who you can trust with his informations.

    Because all us watchers know that you cant trust the not equal voices of journalism.

    Thanks that you provide us with information on both sides of the facts!
    Lets see what happens, and lets hope no one gets hurt.

    1. Second that, great work Jon, Your info has saved a flight this weekend from been canceled.

  2. Jón, I am no expert, but I do share your opinion that something shall still happen, or maybe, is still happening at depth. I don’t know if it is some kind of “magma chamber filling up”, or a “suffocated eruption”, whatever, I don’t see this is over either.
    I trust your “ability of seeing through” tremor graphs. Like a doctor who can “see” there is a problem in an electrocardiogram that other doctors can’t detect.
    Let us wait and hope for the best.
    Many thanks.

    1. The magma is on the move. I think that is a sure thing. But where and what it is going to is a different question all to gather. So far the earthquakes SSE of Grímsvötn continues. This area is inside (on the edge) Grímsfjall volcano. An eruption there would create massive flood and it would take some time for the eruption to get trough the ice, if it would get that far to start with.

      In the news this afternoon they where saying that this eruption in Grímsfjall volcano was the largest one for over 140 years.

      1. If (big if) a new fissure would open up, it would be preceeded by (more) earthquakes wouldn’t it? (in order to penetrate the crust)

      2. Yes, there would be a lot of earthquakes in that case. As always happens when magma creates new pathways for it go in the crust.

      1. Please tell me what is the substantial difference between mist and steam? ;D Both are water in a vapourated state. Activity at Katla will never be observed by webcam first. If ever activity will start at Katla it will be preceeded by many earthquakes.

      2. My friends, please, you cannot see steaming in Katla, because the ice there is 600m thick. If lava comes to surface, it causes lots of earthquakes and a big explosion. The volcano is hidden beneath a massive ice cap.

        Grimsvotn and Bardarbunga are likewise hidden beneath a massive ice cap. Hofjokull, Langjokull, Esjufjoll, Oraefajokull are also hidden beneath glaciers. There is widespread geothermal activity under the ice in Katla and Grimsvotn.

        However, Laki and Eldgjá fissures happened outside of the ice caps, in ice-free regions (but only snow-free during summer). There is no steaming, no geothermal activity nor earthquakes there, only the old craters and fissures.

        Hekla has the ground on its top steaming because last eruption was 11 years ago. The ground is hot but only on the very top. Most often Hekla is hidden with clouds and fog on its top. Hekla has only some snow on its top, no glaciers.

        Eyjafjallajokull has been steaming for several months since past eruption. The steam column is sometimes big enough to be seen from distance (where I live). There is a glacier at its top, and a new crater lake now. Hot lava could still be seen there last summer (in the hiking trail).

        Another example of a volcano still steaming is Krafla, 40 years after its eruption. So is the top of the volcano in the Westman Islands (dig it 10cm and it is hot). Askja also has a warm lake. None of these volcanoes have glaciers.

        If you want, come to Iceland (best time July to August), and check these warm volcanoes for yourself. (except for of course the ones under the glaciers!)

  3. ignore the question in this moment, but maybe when you got time and this is over, you could think about getting dual language dunno right now if wordpress got the option for dual blogging, but you all know how bad google (the best translation so for) is with your language 🙂

  4. If I had lurkings plotting skills I would love to do a 3d tremor graph map across iceland (a bit like a map that plots elevation and deformations above sea level) and do this at montly intervals then sequence the resulting images to see if the tremor maps showed anything particularly interesting in terms of overall patterns and changes. I havent got a clue though as to how to go about this.

    I have noticed for some while that the tremor signatures are seperated into at least two main ‘groups’ where the overall pattern of tremors at different stations have been mirroring each other, and reflecting peaks and troughs – much like we are seeing now but on a far smaller scale. I assumed that it may have something to do with the locations of the SIL stations relative to the main fault lines. There may be nothing in it but this observation has intrigued me for some while, and I have been seeking an explanation for it.

    Most easily seen when you scan down this and look for patterns

    1. Plotting tremors in 3D style is no good unless you can get some position info out of them. I don’t even have the raw data to even attempt to get a 2d bearing cut from similarities in the various tremor graphs. (relative magnitudes).

      I tried it last night with a couple of the graphs but it was a mess and yielded nothing of use.

      The people who do this stuff for a living could use tomographic techniques to localize the subterranean features, but that will likely occur in the after action research and show up in a paper later down the line. (note: tomographic techniques are outside of my skill set)

      Being a rather quiet volcano quake wise… there isn’t much for me to plot.

  5. Anna Island on May 25, 2011, 12:26 PM
    Jón Frímann made the national news here in Iceland today!

    I picked up a paper copy of the largest newspaper around noontime and there he was, taking up most of the back page!

    Jón was the first person to put out an alert on Saturday morning (on his blog). The press took note. Almost an hour passed before the authorities announced that an eruption had started.
    Congrattulationd Jhon!!! ;D

    1. Yes, Jon and his blog following has his finger on the pulse probably closer than those getting paid for it, however, I believe Jon could get paid for it as there are MANY people like myself out there who would love advanced real time notice as soon as it looks ready to blow, which in the case of Grims was less than 2 hours and could be even less for Katla. Just my 2 cents.

  6. There seems to be a small increase in the tremor at 0.5 – 2 Hz at stations
    near Grímsvötn. In GRF has a strange behavior with the closest.

  7. Tremor: deep or shallow?
    Triangulation of tremor signals.
    Looks like it is becoming possible to use tremor signals from an array of detectors to locate the tremor source. I remember commenting when Eyjaf was active that if it were feasible it would provide useful information. My guess is the Icelandic geophysicists will be trying to use this method now. They have huge amounts of tremor data they have collected at sites 100km around Grimsvotn.…/2001JB000559.shtml

    1. I thought I heard that they’re sorely lacking quality instrumentation around and on Vatnajøkull Glacier. If that’s so I would think that any attempts at trinagulation would begin somewhere where they had better distribution of instrumentation, like on Myrdalsjøkull with Katla and Eyafjallajøkull.

      Also, the 0.5 to 1 hz plot travels from 2000 to 7000 nm/s in under an hour. That’s a lot of action – and is a continuation of the extreme lows and highs of the current tremor plot for Grimsfjall.

      1. I suspect that the array they have in place now would allow a triangulation to distinguish between say near-surface/ 20km deep /35km deep.
        Its curious that during the GPS inflation since 2004 there were almost no EQS deeper than 20km despite the big rise in EQS shallower than 20km. So if magma was then rising from the mantle ( 35km depth) it must have moved silently. Is it making tremor from that depth now?
        I’d like to see the tremor return to baseline before signing off Grimsvotn.

      2. The problem with the seismometers is, that they need to be set up on solid ground. And on the Vatnajökull there is only one peak fullfilling these criteria: Grimsfjall.

      3. But the tremor from Grimsvotn is being detected at seismometers 50-1ookm away. So the array has a huge baseline that should help with depth resolution.

      4. What about Hvannadalshnjukur? Too close to the edge to be of any use?

      5. Is there a station on the summit that is not on the website-maps or do you mean the station at the coast (fag)?

  8. Magnitude mb 4.9
    Date time 2011-05-25 16:55:37.0 UTC
    Location 74.28 N ; 9.29 E
    Depth 12 km
    Distances 1011 km NW Murmansk (pop 319,263 ; local time 20:55:37.2 2011-05-25)
    610 km NW Tromsø (pop 52,436 ; local time 18:55:37.2 2011-05-25)
    467 km SW Longyearbyen (pop 1,232 ; local time 18:55:37.2 2011-05-25)

  9. I have spotted two low period earthquakes on the Grímsvötn SIL station (in the tremor noise). Sadly, I do not know where they are located.

    1. Is that when the red line goes crazy. Not really looked at tremors before this eruption. Now I keep looking at them all the time. But I do not know what I’m looking at.

      1. Earthquakes create spike in the IMO tremor plot. Low period earthquake create spikes that go from 0.5 – 1H z band. But sometimes long period earthquakes also do this. So it is sometimes hard to know the difference.

        But by comparing time this can often be done properly.

    1. So if I were to travel to Grimsvotn from England I would be slightly heavier than I am here. Thus as I am spot on my goal weight, If I visit I must go on a diet first or will have to diet all through my holiday. Is that how it works? However, if I go over-weight I can still pig out on holiday if I go to Uganda instead?

  10. Sulphurous smelly air just reached us in Torbay, Devon, UK. Not sure if it is from Grimvotn as it smells not ony of hydrogen sulphide, but also sulphur dioxide and thiols so might be of industrial origin. It’s a bit of a coincidence though as I have never smelled it here before. I have not noticed any ash, but have put out black and white shiny papers to see if I can collect any.

  11. Jon
    Oh thats good!
    Can you find the signature of same individual LPEs in the other stations such as skr, kal ,fag,kre, vsh. They must be a few tens of seconds later depending upon separation, as you well know!
    I think it would be legitimate – initially- to assume the xy coordinates of the source are Grimsvatn. So after allowing for distance from Grim the time differences would reflect depth.
    Those papers I cited were looking for few-100m resolution. You only need multi-km resolution in depth to make a real splash!!
    Front page next time, and a research paper to your name.

    1. Hmm! perhaps low cloud. I can’t find any other signs of anything going on, but if Godabunga is hydrothermal activity, then and there has been a small swarm there, perhaps hydrothermal origin steam may be venting.

      1. This is not Godabunga but the central caldera of Eyjafjallajökull, as Jon said, it has been steaming for months now, nothing new I’m sorry, it does look nice though, with a bit of fantasy we can travel back in time and see the eruption again. 🙂 hehe

        Oh and there has not been any swarm at Godabunga, Godabunga has been unusually inactive last year compared to the last 10 years, in which 10-15 earthquakes per day were not unusual.

      2. OK, more active than recently then. Of course I have only been watching it since Eyjafjallajökull erupted so know nothing of what it has done prior to that.

      3. It is all quiet in Katla and has been for a long time. When something of interest starts in Katla. I am sure that you and everyone else is going to know about it.

  12. Wednesday
    25.05.2011 18:34:45 64.296 -17.098 12.6 km 1.2 99.0 14.7 km SE of Grímsfja

    1. Sorry was meant to reply to this

      So if I were to travel to Grimsvotn from England I would be slightly heavier than I am here. Thus as I am spot on my goal weight, If I visit I must go on a diet first or will have to diet all through my holiday. Is that how it works? However, if I go over-weight I can still pig out on holiday if I go to Uganda instead?

  13. When I see earthquakes ranging up to m4.0-ish under Myrdalsjökull I will get concerned..Not before that.

    Tremors on the charts are often erratic. This is often due to hard wind and noise from the ocean crashing in on the coast.

    On the Katla webcam there are often images which resembles steam or a plume. But these are just local clouds beeing created and vanishing. This is quite a common phenomenon. Look at the picture below which I took during the Eyjafjallajökull eruption. It looks like a trail of smoke coming from Katla but in reality it is a cloud created by the micro climate surounding the glacier.

    1. But not erratic in such a way that they all respond with the same pattern. Thats the give away to a widespread signal– maybe from depth??

  14. And Jon has got humour to, quote: “and they can throw up rocks that weight up to 1 ton. If anyone gets hit by that rock, that person does not have to worry about what happens next”. I like that, very funny!


    1. Grímsvötn is an lake in caldera of Grímsfjall volcano. They are in the same place. Icelanders often refer to Grímsfjall as Grímsvötn, because you cannot actually see the mountain due the glacier that is around it.

      1. thanks, so vötn is a lake and fjall is a mountain in Icelandic? Does the word grim also mean anything?

  15. I am sure this was discussed earlier, but what is the background behind each frequency? (0,5-1-2Hz)

    Can i assume that lower frequencies are being generated by bigger mass from the deep (magma), while the higher one is caused by interaction between steam (air) and rocks?

    What i see now is that the lower frequencies are increasing west from Grímsvötn, could this mean magma movement along the Lakagigar fault line? I don’t see this increase on the southern side.

  16. It looks like the amount of tremor is varying wildly, showing as a very wide band on the plot and getting wider. Does anyone understand why?

  17. Perhaps we still have a sub glacial eruption somewhere under vatnajokull.

    1. Not likely at this point. There where no earthquakes that suggest that is the case. The earthquakes that where SSE of Grímsfjall where to small and to scattered to signal an fissure opening up at that location.

      Now it is just question to wait and see what happens. Waiting is short of an sport in geology.

  18. What is not clear to me is that no drops of water by melting ice, unless the water has entered the crater and the output has collapsed creating a plug of magma or lava crust cold, the lack of earthquakes may magma conduits are full but lacks pressure, little by little by increased tremors seeking outlets moving is easy, and perhaps the magnitude of the tremor is due to gasification, that’s what we believe, may not have nothing certain is speculation. I do not think that an eruption that reaches 20 km in 48 hours no more signs of water vapor

    1. Heh, gasification, that what I was thinking as well. Maybe what we’re seeing with the oscillating tremors is a giant volcanic belch after the short and extremely intense eruption. Then again, would such an event of gaseous releases produce harmonic tremors? I thought only magma could produce such stellar example of harmonic tremors as we’re seeing in the Grimsfjall plot at the moment.

  19. I realise I need to get a life, and probably irrelevant to anything going on at the moment, but if two or more volcanic vents form close to each other, both or all producing tremor, do we get interferrence patterns in the tremor? I realise it is very sad and I need to get a life if I sit about thinking about things like this, but I am curious.

    1. Two vents
      How’s this for pure idle speculation:
      Since the tremors cant be localised I suppose we cant be sure they are coming from Grimsvotn. If its not from Grims it must be close as the amplitude is greater on the Grimsfjall detector than any of the others surrounding Vatnajokull.
      If there were EQs under any of the other volcanoes nearby we’d be expecting more action. Unless the tremor is concealing those EQS, making it ipossibel toresolve them.
      Jon: is that possible?

  20. Also, has anyone checked if the lake is still there? If it fell into the emptying magma chamber, that would have accounted for the abnormal size of the eruption for that volcano, and also the short duration and sudden end. Or would that actually be more cataclysmic even still?

    1. The news article Jòn linked in his post says there is clearly a lot of water present in the fissueres surrounding the active part of the caldera. And normally I think a lack of water would just turn the eruption into a hawaiian style lava eruption instead.

  21. Tremor increasing quite significantly, pretty much to the levels of yesterday.
    One earthquake east of Grimsvotn, but things seems calmer quake-wise

  22. Far as I can tell the tremor noise is currently dropping (going to write about that tomorrow). That might be an good sign. I must remind people that eruptions in Grímsfjall volcano do not last for long most of the time. Longer eruptions are uncommon in this volcano (but they sometimes happen, just not now). So this might all be over for now.

    The the remaining earthquake activity in Grímsfjall volcano is interesting. As normally Grímsfjall volcano does not have many earthquakes, most of the time mostly none at all.

  23. Although this is my first comment – I’ve been reading your blog almost daily since the “Eyja” eruption.

    You’re doing a great job Jón. All you other contributors as well.

    A funny(?) anecdote: The Icelandic word for eruption, eldgos(correct me if im wrong), roughly means “fiery cuddle” in Swedish.

    Keep up the good work all you guys.

  24. OK, folks, this eruption is over.
    Time to place our bets for the next volcano to erupt in Iceland.
    Mine goes to Hekla.

    1. This eruption might be over. But I not think Grímsfjall volcano is done. The earthquake north of Grímsvötn is intersting one, as there has been earthquake activity there in the last two years.

      This area (where the current earthquake is) is known to have had fissure eruptions in the past. The last one was maybe around the year 1938 or earlier. I do not have better information about that at this point in time.

      But it also important to notice that big eruptions are also followed by eruption in Þóðarhyrna volcano that is SV of Grímsfjall volcano. That volcano last did erupt in the year 1902 following an VEI=4 eruption in Grímsfjall volcano. Sadly I do not know the time fram on how this did happen or how often this has happened. But this might be something to look for in coming days and weeks. The eruption time for Þórðarhyrna (Thordarhyrna; english name for this volcano) volcano is as follows.

      Eruption years, 1902-1904, 1887-1889, 1823. Other eruption years are not registerd. But I am sure that they are many more then this that are currently registerd. But there are 107 years since Þórðarhyrna volcano last erupted. So with increased activity in Grímsfjall volcano it might also awaken.

      Grímsfjall volcano history,

      1. Wow!
        Better start learning the name from now.
        Þórðarhyrna, cool! 🙂
        Jón, you rock.

      2. Well… all I can add to that is the quakes that that I have plotted over the last year or so show a trend that drops down towards Thórðarhyrna.

        In fact, the eruption seems to have been at the top of that stack.

        Dunno if that helps.

      3. If you look at the tremor charts and the amplitude of the tremor on the different charts you can see that Grimsfjall, Skrokkalda, Kalfafell and Vatnsfell have the largest amplitude compared to other tremor measurement stations. Other stations around Vatnajökull also have higher amplitudes and frequencies than usual. But most action is definately in the south-west of Vatnajökull.

      4. Both the Wikipedia page on Thordarhyrna, and the for Grimsfjäll mention the 3550 BC eruption of Thordarhyrna, which poured 1,5 km3 of lava, so this “little brother” can be really angry sometimes…

  25. Are you setting up an Iceland volcano sweepstake Renato?
    I (with no knowledge of this sort of thing) might play a wild card on this & say it’ll be a volcano that you guys are not talking about erupting (unlikely) but it’ll probably be Katla or Hekla (now i’m hedging my bets).

    1. Wurzeldave:
      Every now and then we do this kind of “sweepstake” over the blog. Normally, when it is calmer.
      But Jón’s last comment made me change my mind:
      Þórðarhyrna !!!!

  26. Hey, it looks to me like renewed activity (ash fall) is showing at Grim cam.
    Could anyone check, please?

    1. Looked to me that there was some renewed activity when I looked first, definitely something is bubbling

  27. Jón, what do you consider the chances of something happening in the Esjufjöll area?

    Herdubreid or Herdubreidartögl is another area to have had a lot of (eq) activity over the past year or so. What about a nice Hawaiian eruption at the peak of Herdubreid with rivers of lava cascading down that most beautiful tuya?

    PS. R Duke – better “eldgos” than “fredagsmys”.

    1. Besides earthquakes that indicate minor magma inflow into Esjufjöll volcano. There is not a lot happening in Esjufjöll. But it is also impossible to know if anything is happening there until it happens.

  28. If I come to Iceland for my vacation this summer to witness the smoldering remains of Grimsvotn. to take in the wonder of such a mysterious land, and to sample the night life in Reykjavik, and perhaps to experience romance and encounter some of the more beautiful decents of the great and rugged vikings, is this what I am to expect:

    If so, I’m in!

  29. Tremor signal getting very intense, most notably at the following SIL stations: – ada; ask; bru; god; grf (large); gyg; hau; hva; kal; kre; mko; rju; sly (large); smj; skr (very large); vat (large); vsh.

    Lurking – if we cant plot the tremor strength vs location, any chance of mapping this lot.

    Somethings up.

  30. By the way – thankyou for all you do – just reread that and it sounded a little terse. Sorry!

    1. Note to self – check things first. It is a waterfall that is always there!

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