Posted on by Jón Frímann

General overview of Grímsvötn eruption on 23. May 2011 at 20:33 UTC

This is a general overview of Grímsvötn eruption on 23. May 2011 at 20:33 UTC.

Ash cloud: The ash cloud is still going strong. It is however a bit lower then in first few days. Measurements of the ash plume now says that it is between 5 to 9 km. Because of that it does not appear on the radar at IMO. The ash cloud has now been detected all over Iceland, except for the most western part of Iceland (Westfjod). In the areas closest to the main ash cloud the visibility is from 1 meter and up to 500 meters when it is at it’s best. Ash fall is expected to last for the next few days, or until the crater does not get any water into it to make the ash. The ash cloud is expected to reach Scotland tonight (Rúv, Icelandic). BBC News about cancelled flights due the ash cloud. Farmers live stock has started to die due to the ash cloud. It is unknown how the wild life is doing while the ash cloud covers part of south Iceland. Current output of the Grímsfjall volcano is about 1000 to 2000 tons of ash pr second. It was around 10,000 tons of ash pr second during the first days of the eruption.

Rúv News, Öskufall næstu daga (Icelandic, Rúv.is)

Eruption: Even if the ash cloud is lower now. It appears that the eruption is still going strong. In the evening news at Rúv it was reported that there was a chance the magma that powers this eruption might be from a great depth (more then 20 km). Tremor graphs that are online show and suggest that the eruption is still at full power. The reason why they are at lower noise level is most likely due to fewer explosion in the eruption, as less water is in the crater. When water no longer goes into the crater it turns into lava eruption. There is also an speculation that new fissures might open up in this eruption where there is more glacier cover (evening news on Rúv). But that would mean flash glacier flood and new ash cloud when the eruption would break the glacier covering it. But so far this has not happened and is nothing but a speculation. It would mean earthquake activity when the magma would break the crust, as happened when the eruption did start on 21. May 2011.

GPS data: According to report from IMO and University of Iceland the deflation now has been 50 cm to northwest and has subsided 25 cm. According to the report this about 60% larger then after the eruptions in the year 1998 and in the year 2004.

Web cameras: Grímsvötn Míla web cam is now up and running. It should be possible to see the eruption when an ash cloud is not in the way. But so far that has been the case.

Please note that information here might get outdated really fast and with no warning at all!

Updated at 20:42 UTC.

144 Replies to “General overview of Grímsvötn eruption on 23. May 2011 at 20:33 UTC”

  1. Do you now the exact position of the new webcam? And in what direction it’s focused?

    1. I guess that it has been set up at the observation hut on the edge of the caldera pointing to the eruption. As far as I know, Míla has some technical equipment up there, so the setup was quite easy. I can ask a friend about this in the next days.

      1. I highly doubt that, from what I can see now it’s set up above some valley, with a river flowing beneath. Setting up a webcam at the mountain hut would be crazy now, as this hut might currently be tens of meters away from the actual eruption. I think no one has travelled over the glacier since the start of the eruption yet, it’s just too dangerous.

      2. Good point. I ask my friend, but this might take a few days, since he can’t come back due too closed roads.

  2. Re flights, here’s a small curiosity: president Obama shortened his state visit to Ireland and left early tonight (was supposed to stay until tomorrow) to prevent Air Force One to be stranded because of the ash. Irish Met service expects moderate ash amount across the island early tomorrow morning and during the first part of the day, most likely resulting in closure of air space.

  3. Apologies if this has already been posted, but Vimeo is hosting a stunning video of the eruption cloud shot by Jon Gustafsson from a helicopter:

    Video here.

    I don’t think I’m alone in thinking Jon is a very lucky guy to get to see that.

  4. Cheers for the update Jon, fantastic work on the blog over the last few days. Learning so much from all the postings so thanks.

  5. http://www.ruv.is/frett/ekkert-akvedid-um-folksflutninga

    According to the article, 2000 tons are being ejected every second. That’s approximately 700 cu m per second, 2,500,000 per hour and 60,000,000 per day. A guesstimate based on this would be a total of about 150,000,000 – 200,000,000 cu m (0,15 – 0,20 cu km), a comfortable VEI 4 and more than the entire output of Eyjafjallajökull in a little over 48 hours.

  6. First I would like to say thank you, Jon for all your effort till now. Learned something new last days.

    My question is, how deep could chamber of this particular volcano go. 20 km deep? Or is it already common chamber, shared by many volcanoes nearby?

    1. Well first of all, scrap the thought of an actual chamber. What is taught at school is that a magma chamber is a conventional circular-shaped hollow space. But infact, most of the magma ‘chambers’ are cracks and sill’s in the earth’s crust filled with magma. The theory goes that these sills have deep connections in the Vatnajökull area, which has not yet been (and probably can not be) proven.

      These sills are partially, or completely molten most of the time, an eruption occures when a fresh intrusion rises from the moho, which forms a dike (feeder). The added pressure, reaches a breaking point, on which the pressure is large enough to break through the crust above and start an eruption. Or the pressure is maintained and a laccolihth forms (see next paragraph).

      The circular shaped idea of a magma chamber comes from the existence of domes (laccoliths) which are actually a stage further than sills. They are located shallower than 3km (so the pressure of the bedrock is low enough in order to lift the ground). This dome shaped ‘chamber’ causes a deformation on the surface, which can be observed. As far as I know, this is the case at Grimsvötn. Grimsvötn has a laccolith at about 1-2km depth which is constantly being filled and therefor it has frequent eruptions.

      More info:
      http://en.wikipedia.org/wiki/Laccolith
      http://nl.wikipedia.org/wiki/Bestand:Igneous_structures.jpg (C is laccolith)

      2. Turkey Mountain – New Mexico

        An ancient laccolith with all the overburden eroded away. Good visual via either Google Earth or Nasa Worldwind.

        35.982596° -104.888828°

        (35.982596°N 104.888828°W)

  7. Thank you Jon and all of the knowledgeable people commenting too – I am learning a lot about eruptions very quickly!

    I do have one question though. All of the TV documentaries about volcanoes are full of doom about pyroclastic flows. As no-one has mentioned that possibility here, I assume it is not a possibility at Grimsvotn. Is there a reason for that?

    Thanks in advance!

    1. It is most certainly a possibility with this eruption. The volcano is in a remote area so the pyroclastic flows are probably not harming anyone directly.

    2. What I believe is that in order to have pyroclastic flows, the eruption cloud has to get so dense that it collapses under it’s own weight. So I assume that this volcano (along with most other Icelandic volcanoes) do either have to weak eruptions, or the composition of the ash is different. It has rather recently been discovered that Hekla has occasionally did have pyroclastic surges.

      I did find a historical record of a small surge at Grimsvotn during the 1998 eruption:
      ‘An overflight on 20 December from 1045 to 1215 revealed variable activity. The eruption plume extended to 7 km altitude. Initially the plume was light-colored, and narrow at its base. Later the ash content of the plume greatly increased, and the plume turned black. It collapsed down to 1-2 km, created a base surge, and Mt. Grímsfjall disappeared into an ash cloud.’

      Source:
      http://www.volcano.si.edu/world/volcano.cfm?vnum=1703-01=&volpage=var#bgvn_2311

    3. Eruption column collapse is one of the ways that a pyroclastic flow can form. The most common way is a dome collapse, where parts of a hot volcanic plug break off and, in combination with newly erupted ash and gas, form a flow. The Soufrière Hills in Montserrat release this kind of flow often. That doesn’t happen often in Iceland because most of the magma is much less viscous, so a plug doesn’t form.

  8. On the Jökulsárlón cam there is something odd to my eyes .
    the far left shows the fuzzy plume but on the right there is a ?plume showing it could be weather or ?

    1. Amazing pictures. Both beautiful and terrifying.

      But given the responses to my earlier question up-thread (thank you guys!), I’d stay well away!

    2. Thank you for the link! Wow.. Starting to get an idea of what the eruption looks like.

    1. Yes its sloppy isnt it!
      Dont know the answer – comparing current values it looks like factor of two difference -odd.
      Time constant probably shorter in the latter plot, so peak looks much higher ( and peak in first plot lost off-scale too?).

      1. On the map page for the first plot it says:
        “….average vertical movement per minute for each seismometer”. Still no units of length, but at least we know its in minutes.

        Glad h/she not one of my students.
        (probably would be a reciprocated sentiment)

  12. Fireman’s link:
    http://en.vedur.is/media/jar/Grimsvotn_status_2011-05-23_IES_IMO.pdf
    ( thanks Mike) tells us the ash sample on the ground contained 10% of particles of 10micrometre ( 10 micron) size or below.
    That particle size settles out of air suspension at around 1 to 3 cm per sec, depending upon height above sea level:
    http://www.geo.mtu.edu/~raman/papers/Rose&DurantJVGR09.pdf
    ( figure1)
    So from Henrik’s post we can see that roughly 200 tons of these particles is being ejected per second, to a height at present of – what?- 3000m?
    It would take – in the absence of rain etc – about 50 hrs to fall out.

  13. Well here in Wales we seem to be getting the first whiffs of ash and there is a very ‘dirty’ as in hazy or fuzzy area above the cloud bank over the Irish Sea where the sun has just set. Oh well, the wind has been very strong today so hopefully it will disperse pretty quickly.

    1. Hi Alison
      I’m in N Wales too. I shall go ouside and sniff the air. Mind you we collected ash from Eyjaf but smelled nothing- but that could be age-related.
      Peter

  15. The harmonic tremor from Grímsvötn eruption is slowly dropping for the moment. But even so the eruption is still quite powerful one. For most part this is going the normal route of the eruption on Grímsvötn, so far anyway. I do not know what happens if more magma comes to the surface from great depth.

  17. The videos and photos you guys posted, are absolutely amazing, and make me wanting to go there flying or with jeep. Having gone to Kirkjabaerklustur seemed nice but nothing outstanding.

    The plume kept hidden or not visible since my last sighting today morning and at lunch time. I will check now again, to see if I can see the plume or not. The sky is damn overcast and probably the ash cloud still hides the column.

    1. London got whiffs of it mon eve, preceded by some very nice stratospheric clouds. This will be big. Not much of a warm week to follow! (Lovely crisp, swift northerly wind too)

      2. @scuj1… We will wait and see!
        I just wish the poor folks in Iceland weren’t so covered in it.

      3. Really? It supposedly reached Scotland and Ireland at around seven this morning. The ash can’t have spread to London yet. (I am in Surrey, and if it had spread as far as London by two in the morning it would definitely be here by now.) This evening, fair enough, but I wouldn’t worry for the moment.

      4. Non here in Devon (extreme SW England) yet – no smell, no ash.

  21. Looking now at Jökulsárlón webcam I see what could be a very dark ash column. It looks very much like yesterday’s approaching plume. Looking closely at the left corner of the visible sky you will notice something similar to an eruption, but that could again be one of those light tricks.

  22. OK, I see that tomorrow everyone is going to be talking about the flight cancellations coming to London. Look at the simulation, tomorrow afternoon the ash cloud will reach Dublin, London, Copenhagen and Southern Scandinavia (Oslo).

    http://www.metoffice.gov.uk/aviation/vaac/data/VAG_1306194460.png

    I am not sure if now the red ash cloud in this model, means risk to airlines. The ash will persist much less time in the atmosphere, and will be at lower altitudes.

    Also interesting is the fact that the eruption already released more ash than Eyjafjallajokull in its entire month eruption!

      2. Thank you scuj1 , great link,i wondered the colour coding too. It would be interesting to know at what altitudes different particulates (mass wise) settled in, regarding wind directions…perhaps.

  23. @Renato Rio
    It is interesting however the eruption is off the range of the cam to the left.
    what i have been watching on the right is very interesting as it appears to be a new eruption site or damn clever weather anomalies. There have been smaller puffs that show about center then go away it could be weather if so when the sun dances around to the nord est it should show the truth

    1. Just looked at the weather bulletin on IMO site, and they say it is raining in this area, so, it’s hard to distinguish in the dusk which is which.

  24. Hi – and thanks for an excellent blog.

    Just to report that when I checked my car just now it was covered with a significant covering of windblown ash. Much more than the Eyja eruption last year!

    I live in Grimsay in the Outer Hebrides of Scotland

    1. and you have a car? There are roads on the island? I’ve never been, so “What’s it like?”
      Last year in Western France we had ash fall on cars, dust, fine fraction stuff.Eyja ash fall. No ash here so far.
      I’ve been looking at the island you live on in Google, and there are country roads. I could probably see your house with google! good luck!

  25. @Renato Rio
    I agree Iceland’s daylight is rather odd to people who live further south, when i was in the navy i spent time there and found the seasonal changes in day length were hard to got accustom to. To say nothing about the sun rise / set locations changing so fast.

    1. Thanks for the feedback, Gina.
      Light plays indeed weird tricks to unaware eyes.
      I think it is getting brighter now and we can see more clearly what is going on at Jokülasárlón.
      But ashes still turn day into night near “grim” Grimsvötn. 🙂

  26. There seem to be 3 locations that toss up dark substance or clouds that blow away after a while then do it again. and it is probable a anomaly but with my screen magnified all the way it seems to have red flickers occasionally in the area

  27. I noticed this about 5 pm est as a disruption to the skyline under the clouds i am now wondering if it isn’t a fissure opening as it started with one point and now seems to be 3 separate yet close appearing

    2. When the water no longer gets into the crater. It is going to turn into lava eruption. There is a chance that some of that might already has started to happen in Grímsvötn eruption.

      At least the explosions are smaller now then in the beginning.

  29. Jon, have you heard if the TS-Sif plane of the Icelandic coastguard will be able to use the same camera/radar that captured the Eyefjallajökull image of the three main craters? Or is the conditions on Grimsfjall too different/difficult for that?

  31. Ok. Maybe I come to conclusion too quickly from seeing the blurred images available. Car lights are gone.
    But now I clearly see big waves battering the central iceberg in Jokülsárlón cam. Is this a normal occurrence when tides invert, coming from land to sea, or else this could be a sign of a jökulhlaup?

    1. Now the big waves rising from behind the ice has ceased, but we notice that the winds are blowing heavily from the lake to the coast. Interesting effect.
      And of course if the waves had covered the chunks of ice, they would have washed all ash away. Let us wait and see.

    2. Now the big waves rising from behind the ice has ceased, but we notice that the winds are blowing heavily from the lake to the coast. Interesting effect.
      And of course if the waves had covered the chunks of ice, they would have washed all ash away. Let us wait and see.

  33. Gina, Renato. Those clouds behave strangely indeed! Unfortunately the resolution is too low as well as the light playing tricks with the sun behind. Sometimes it does look a bit like an ash-laden eruption column might, at other times it looks as no more than unrealted wisps of cloud. Of course it could be something vulcanologically interesting, however unlikely, but it could also be no more than the backside of sunlit clouds.

    1. Henrik:
      If you are talking about the waves, they were doubtlessly waves, as you seem them hitting coastal cliffs – that was no illusion. Neither the car lights, a pity that I didn’t grab any screen shots (who would be driving so close to an erupting volcano?). It could be well some kind of strombolian explosion, even though I have no clue as for the scales involved.
      But you are right when you say we must be seeing “ghosts” here. Everything looks like phantasmagoria to be stated as real.

  34. In a couple hours the sun will be behind the cam then we will see.
    the sun rises roughly in the north-east then crawls around the south horizon perhaps 30 degrees elevation at noon then sets in the north west so my memory tells me from my last visit to iceland

  35. Maybe this eruption is coming to an end, but tremor levels are still very high, all over the place, indicating magma is circulating in the depths. But where?

    1. Keeping an eye on Hamarinn is probably not a bad idea. And the “old” eruptionsite Gjalp.

      There was atleast two deep (16km) EQ´s at Hamarinn yesterday within 2 km distance. And Gjalp have had several both deep and shallow.

      Since there is a theoretical connection between the volcanoes under Vatnajökull I would be concerned that some one else decides to join the band and make it go from pop music to heavy metal…(pardon the metaphores) 🙂

  36. Gina, your cloud is very persistent and won’t go away, nor move. Now, I’m not a meteorologist but surely clouds don’t do that!

  37. It’s not unusual for ‘permenant’ clouds to appear above mountains in strong wind conditions. As the wind passes over the mountain it gets compressed and moisture is effectively squeezed out in the form of a cloud.

    1. I think it is just a cloud, but I am not certain. We will have to see if it is still there in an hour.

      1. It’s been there, in the same position for more than 12 hours now… 😉

    2. It seems to form from behind the mountain and gradually dissipate. If it is a plume it is a small one – but perhpas it is. Where would that be on a map?

      1. It’s a glacier south east of grimsvotn and the camera is pointing north, with the current northern wind it’s not likely that the (ash)cloud is moving from left through right through the view of the webcam

    3. There are several places where the clouds keep forming at the same point, rising and dissapating. It is easy to imagine it is a fissure opening, but it is easy to imagine things in clouds. Maybe it is real though. It will eventually get reported if it is real.

      1. You’re quite correct, Treacleminer. The easiest explanation is that the wind is channeled over that point and carries ash with it, hence the dark appearance.

    1. No, it is either clouds egding round the mountains taking the same route every time, or a plume of some form. There isn’t a power plant there or anything is there – which might have chimneys?

      1. In this area there is nothing but snow, ice and volcanoes. No factory or human population of any type. Some huts for study of the ice and volcanoes and that is about it.

      2. No, this is literally in the middle of nowhere. This is on the glacier, the next bigger settlements should be Skaftafell (which is fairly small) and Kirkjubaejarklaustur (which is a bit bigger, around 300 people are living there).

  40. Just had a look at the harmonic tremor chart for Grimsfjallon the IMO website and it looks like its on the rise again.

    2. I also noticed that.. quite sharp increase…
      Think this eruption is far from over ..:P and that there might be some unpleasant surprises on their way…

      1. Totally agree with you Sander 🙂
        I’m certainly no expert in anyway but I wouldn’t mind betting there’s more than just the one vent at work here
        (Quite possibly the most obvious statement of the day so far haha!)

    3. Yes i agree with you. If a fissural eruption starts it will appear there isn’t it? Sorry by silly question!

      1. If a fissure were to open up I bet it would be the old Gjalp fissure from the previous eruption since there has been quite some activity in this area with a lot of earthquakes. Now this would be really bad since there would be yet another interaction between water and magma. This would certainly be bad for european airtraffic if the winds are not in our favor.

        But it is really anyones bet. As Jón said yesterday the geologists suspect that the magma feeding this eruption originates from a very deep source. Although it will most probably choose the easiest path to the surface it might form new pathways if the pressure exceeds the capacity of the existing tube and then the possibility of a new fissure opening up isn´t that far fetched.

        NOTE! All speculation from my part and I may be waay off target here. 🙂

  43. I thought Carl le Strange on Muesli would come back to this site for this eruption. Last I heard of him he was planning a trip to remote bits of Iceland – then he disappeared. I do hope he is OK.

    1. Yes, I too miss Carl’s contribution to this blogsite and share your concern for his welfare as i thought this event would have drawn a comment from him.

      Also, these photos, posted earlier in a post by fireman are worth a look, I especially liked # 14, and around 24-29.
      http://www.visir.is/album/20110523/FRETTIR/523009992

      Was not sure if Mila Webcam was wind or ground shaking, sure is junpy, but cannot see eruption, is it pointing too far to the right?

  45. There is a chance that less tremors means less explosive eruption. But magma exploding when it gets into contact with ice or water makes a lot of noise and a lot of tremor when that happens.

    I would not be surprised to see the tremor plot drop as the ash cloud goes away and this eruption turns into lava type of eruption.

    But if a new fissures opens up. The ash cloud is going to return and then even flood might happen. But if this happens, it might take week or more until it does. It is going to depend on how long this eruption is going to last.

    1. So what you are saying is that when less water is present in the crater the tremor should drop instead of increase? So the increasing tremors and the lower ash plume is strange?

      Sander

      1. As Chris stated earlier there is a very strong wind and the plume might just be “bent” a bit.

      2. I know 🙂 But the wind is already strong for 24 hours or so and it still dropped 5km..

  46. Thanks for this brilliant blog, Jon. I have been reading back through the different stages of this build-up – starting with the 30 earthquakes in September under the Queen B and the subsequent glacier melt in October-November and then –
    http://icelandgeology.net/?cat=7

    Was it Irpsit who bet that Grimsvotn would erupt before you completed your house move?

    http://www.soest.hawaii.edu/GG/FACULTY/ITO/Reprints/Ito_Shen_Hirth_Wolfe99.pdf

    How does this theory contrast with Foulger? It looks like it might address the deep source etc.

    And incidentally the strong smell last night only lasted about an hour and there is very little of anything on the car this morning – more than nothing, but just a few flecks – nothing like last year when the roads showed clear tyre tracks through the ash and the car had a light covering on several days. It is still early days, however!

  47. Sky News interview with Katheryn Goodenough from the Royal Geological Survey – “most powerful eruption seen in Iceland for 50 years”

  49. Strong winds can decrease the height of a volcanic plume. A shortened plume does not neccesarily indicate a reduction in volcanic activity

    1. Shaking on the Mila cam of Grimsvötn, is it the wind or tremors that are the cause?

      1. It’s all the little goblins which live in volcanos running for their lives what is shaking the camera.

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