Magma movements under Hekla volcano have been confirmed

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According to the news on Rúv the GPS movements that many have been seeing around Hekla volcano in the past few days are real. At the moment the civil disaster authorities have been notified and also local emergency authorities. Nobody seems to know what is going on with this magma moments for the moment. But they can be tracked with the GPS network to some extent. What is more interesting is that this does not seems to have started until few days ago. But first signals of this happening did take place in April and May, but at lot smaller scale. What is interesting is that fact that no earthquakes appear during this magma movements, there is also no harmonic tremor when the magma is moving around in the crust close to Hekla volcano. But if there is any earthquakes, noise or whatever coming from Hekla volcano it is going to appear on my geophone that is located about 16 km away from peak of Hekla volcano. The distance is even less from the actual edge of the Hekla volcano system it self.

Normally, there are no changes in the GPS network before an eruption in Hekla volcano. So this is highly unusual event in Hekla volcano since instrumental monitoring started few decades ago.

It is an question if this means an fissure style of eruption is going to take place in Hekla volcano. But that does sometimes happen, as with any volcano in Iceland. For the moment however the only thing that can be done is wait and speculate (within reason).

No eruption has started in Hekla volcano. But it can be assured that it might start without any warning and I might not be around the computer when that start, since I am working during the day and feeling tiered during the evening. But I am getting slightly better on that front, thankfully.

I am going to post more on this when I do know more, or if anything happens in Hekla volcano related to this.

Icelandic News about this.

Hræringar í Heklu (Rú, Icelandic)

This entry was posted in GPS data, Hekla, Inflation, Magma, Volcano. Bookmark the permalink.

83 Responses to Magma movements under Hekla volcano have been confirmed

  1. Renato Rio says:

    Jón, that’s incredible news. Many thanks.
    I only hope it won’t start right under your feet while at work. :)
    Take care!

    • Renato Rio says:

      There was some shaking under Torfajökull volcano.
      Could be this related to Hekla?
      15:06:05 63.958 -19.286 1.0 km 1.1 99.0 11.3 km NNW of Álftavatn

      • Not related to Hekla volcano. But related to Torfajökull volcano. Thanks to an good weather, I did record that earthquake.

        My geophone is that sensitive if the weather is good. So any changes in the behaviour of that magma that on the move in the Hekla volcano system is going to show instantly on my geophone.

        But beware of the human noise and wind that my geophone also picks up.

      • Renato Rio says:

        And I found this at IMO office, don’t know if it could be related:
        (Giggle translated)
        Skjálftavirknin highest in the South was in the marsh, the southern part of cross-cracks that broke 2008, but there were 75 earthquakes located 29th June – 2 July. Cluster of six earthquakes were located in Hella Heiðarvegur to which Dali 29th June, and the Slot Holst cave was located 14 earthquakes this week.
        Mesta skjálftavirknin á Suðurlandi varð í Flóanum, á syðri hluta Kross-sprungunnar sem brotnaði 2008, en þar voru 75 skjálftar staðsettir 29. júní – 2. júlí. Þyrping sex skjálfta var staðsett við Hellisheiðarveg við Hveradali 29. júní, og við Raufarhólshelli voru 14 skjálftar staðsettir þessa vikuna.

  2. Chris says:

    You can find a short article in english on this in Icelandreview:

  3. Cathy says:

    Is an eruption at Hekla likely to be another aeroplane-stopper, or is it more about the lava?

    Thanks in advance!

  4. Jack @ Finland says:

    I “shot down” Pieter on June for this, so I will confess I was wrong. Being a non-expert, it is all too easy to stick to “stone-written” statistical significance rules, and not to listen to the quiet “whispering”…

    • Pieter says:

      No need to apologize, most of us are just guessing around here as volcanophilic amateurs, and sometimes we get lucky and our crazy theories turn out not to be so crazy after all. Still I doubt that the scientists in Iceland currently have a clear image of what is currently happening beneath Hekla. But something seems to be cookin’ down there. :)

  5. david says:

    So are people in Iceland expecting Hekla to erupt very soon?

  6. Irpsit says:

    I live 50km away from Hekla. If Hekla erupts I will be the first notifying it here. Unless I am travelling. Knowing this, I am not going close to Hekla anytime soon. I think the eruption will start explosive for 2 days, and then change to effusive for a few more days (hopefully).

    Sincerely I don’t want a large eruption. If that happens, it would be a disaster here!

    • Jack @ Finland says:

      How will you prepare for an eruption? Have you been instructed by the authorities? A guess you have face masks already at home, but what else?

  7. david says:

    Interesting that you live so close to Hekla. I understand that it is always a big deal in Iceland when volcano is erupting. I read somewhere that experts said that last eruptions in Hekla were harmless and the next would be small. But i guess you never know for sure.

    I´m going abroad next week so hopefully no major ash cloud would happen if and when Hekla erupts.

    • Daniel_Swe says:

      Given that it has produced a VEI5 eruption in the past and several VEI4 including one plinian eruption reaching over 30km in to the atmosphere I would say that “harmless” is probably not the word to be used here. ;)

      On top of that the recent activity is “unusual” to scientists when it comes to Hekla. That in it self would cause concern.

      My amateur theory:
      Inflation is occuring which is unusual and is likely caused by magmatic movement according to icelandic authorities.

      Now…Previous eruptions has given no warning except earthquakes an hour before or so. Since Hekla is so active I guess this is due to “open-ish” conduits which lets magma rise pretty unhindered.

      This time we have alot of inflation. Would this mean that magma is intruding in a different place? Maybe through older rockformations which makes it harder for magma to rise through?
      If this is the case wouldnt this also mean that the pressure building is alot higher than the previous eruptions. And in the end when she finally blows her top we might be in for yet another plinian/sub-plinian eruption?

      If this is the case could the eruption go through these phases?
      Phase 1. Violent eruption….Plinian/sub-plinian
      Phase 2. Less violent eruption….(Strombolian?)
      Phase 3. Effusive until it stops….

      Just ranting a bit..;)

      • Daniel_Swe says:

        All depending of composition of magma, viscosity and how gas rich it is of course. ;)

  8. Jack @ Finland says:

    I read a few days ago several papers on Hekla. I just made a Google search “Hekla volcano +filetype:pdf”, and downloaded something like over 10 papers (mostly from domain

    In two of them it was stated, that Hekla does not have a magma chamber within the top 14 km of crust below it. It is thought that this explains the short warning time, as the eruption pressure builds up higher (before the onset of an eruption) than for other more typical Icelandic volcanoes (with a magma chamber within the top 3-5 km of crust. As the magma source is deeper, it has to break through a longer road to the surface, increasing the pressure needed (given the closedness of the conduits is equal). Yet, simultaneously this must mean, that the final rise of eruption products happens at speeds of 20-30 km/h which is pretty much unheard before. However, if the initial products are gas- and steam-rich (which they do seems to be based on the initial explosivity of a typical Hekla eruption), all of this seems only plausible!

    It will be really interesting to see, how long does it take for an eruption to start with this inflation. And, whether this inflation is unusual just because we see it now for the first time, or because Hekla is heading for a real big-time show-stopper eruption…

    • Jack @ Finland says:

      The last question is very important. If this kind of inflation is typical for Hekla, a typical eruption is also very likely. It does not matter that we see the inflation for the first time now. However, if this inflation is atypical to Hekla, I’d expect to see a larger eruption…

      Jon: Do you know, was any inflation observed around Hekla before the eruption on 2000? Or, was suitable instrumentation at all available by then?

      • Daniel_Swe says:

        According to the news in Iceland the activities going on at Hekla now is highly unusual. So lets see what happens..

        • Jack @ Finland says:

          Any new links besides the ones given here already?

          • Chris says:

            If you go through the icelandic media, all sites tell basically the same thing. No wonder, since there is actually not more information and this comes all from the same source.

          • Daniel_Swe says:

            Nothing new really but MSM in sweden had a short notice of it. (

            Vulkanen Hekla mullrar på Island och verkar redo för ett utbrott, uppgav professor Pall Einarsson vid Islands universitet på onsdagen.

            – Rörelserna runt Hekla har varit ovanliga under de två till tre senaste dagarna och har noterats av fem väldigt exakta mätare som placerats runt berget, sade Einarsson.

            Hekla Volcano in Iceland is rumbling and seems ready for an eruption, proffessor Pall Einarsson at Icelands university said on wednesday.
            -”The movement around Hekla has been unusual the last two, three days and has been recorded by 5 very accurate measurement devices placed around the mountain, Einarsson said.”

          • Jack @ Finland says:

            Hmm… Tremor plots reveal nothing new. What kind of instruments do they have there?

  9. So how should we compare Hekla against Katla for example? Or even Eyjafjallajökull? Perhaps to early to say yet? :)

  10. Daniel_Swe says:


    ISAK is showing a rapid deflation right now…

    A few days ago ISAK showed a North movement and an Inflation.
    Now it shows almost as much South movement and a deflation.

    Intrusion of magma which has been diverted?

    • Jack @ Finland says:

      Not necessarily deflation. I guess it may also be that the peak is due to flow of a magma “blob”.

  11. david says:

    So the volcano can erupt today, in a week or in a month? I know it is impossible to say when, but arent this signs that it is going to happen very soon?

    by the way, is deflation a bad thing or a good thing?

    Sorry about my stupid questions, this is just all really new to me :)

    • Daniel_Swe says:

      Hekla is kind of special. Last eruption was preceded by earthquakes only one hour before the eruption began.

      So as for predictability I would say Hekla is one of the harder ones to predict. And given the fact that volcanoes are unpredictable by nature makes it all that mor difficult. ;)

      Inflation normally means that magma or hydrothermal features is building pressure and actually lifting the mountain. Like hydraulic in some sense.

      Deflation is the opposite. OR it can also mean that alternative routes has been found and magma is intruding in a different direction away from the area in question.

      This is what i meant Jack. As the amount of millimeters on the UP axis is showing a down trend the ground would be deflating right? If it were a peak wouldnt the level stabilize and keep on the new high level?

      • Chris says:

        This is also a problem of instrumentation. Now there are more and more precise instruments placed around Hekla, so there will be more data recorded.

  12. Luis says:

    Meters around Mt. Hekla in southern Iceland have shown “unusual activity” in recent days. The Public Safety Commission has been alerted. According to RÚV Public Radio there is no reason for action as of now. The movements have been recorded in five very precise meters that have been placed around Mt. Hekla in recent years. Professor Páll Einarsson says that these movements are seen in all five meters and even though the evidence is not conclusive they are thought to show magma movement under the volcano. It has now been eleven years since Mt. Hekla, Iceland’s most famous volcano, erupted. In the years since then the mountain is said to have slowly expanded because of magma buildup. The last eruption in Hekla came on February 26 2000 and then earthquakes started an hour and a half before the outbreak of the magma. As of now there is no cause for any activity on behalf of the Public safety commission.

  13. Splatter says:

    Lets all keep in mind that until rather recently it’s was not possible to measure movements as accurately as it’s today so this movement being unusual is no surprise.

  14. Gitta says:

    Here the CGPS stations are located (click on left side HEKLA)

    And here are the related data (from MJSK to HESA)

  15. Luis says:

    Please tell me what’s the name of the nearest sismic station of Hekla?

    • Gitta says:

      On the map, the individual stations are clicked to find the station code and the location

  16. Jack @ Finland says:

    Jon’s helicorder is pretty close, and sensitive enough to see anything meaningfull happening at Hekla. See Heklubyggd data at

  17. JulesP says:

    I think ISAK station is closest to Hekla

    For a long term view of GPS movements see

    It seems to have been inflating steadily since 2000

  18. Luis says:

    What’s happening in Jhon’s helicorders?

    • Chris says:

      These are the two quakes on the Reykjanes ridge. You can nicely see the P- and S-waves.
      06.07.2011 14:35:22 63.636 -23.196 1.1 km 2.9 90.02 6.5 km SE of Geirfugladrangur
      06.07.2011 14:31:32 63.638 -23.344 10.1 km 3.1 90.02 5.3 km SSW of Geirfugladrangur

  19. treacleminer says:

    Probably picking up whata happening at Reykjanes ridge.

  20. treacleminer says:

    Has an undersea eruption started?

    • Pieter says:

      No, at Jon’s helicorder we can very well distinguish the P and S waves which indicates that these quakes are purely tectonic.

  21. treacleminer says:

    What volcano is there of is it just tectonic?

  22. Pieter says:

    My guess about Hekla; the small spikes of inflation we have been seeing are all failed eruptions, stopped at the last moment because the system is plugged. This could be the reason why the eruption interval is now 1 year longer than ‘normal’.

    • david says:

      Do you know if the situation in Hekla has changed in the last hours.? Do you think it is going to erupt very soon?

      • treacleminer says:

        Yeh, very soon on a geological timescale. That could be a year or more though or it could be 30 minutes,

    • Jack @ Finland says:

      Lurking @ EB:

      Lurking on July 6, 2011, 6:55 PM
      Personally, I don’t see how any mentally competant person can claim that Hekla is overdue.

      Historically, Hekla erupts within 20 years of it’s last eruption about 16.7% of the time.

  23. The inflation spikes in the GPS data suggests an dike intrusion. How deep is hard to say since there where no earthquakes following this. But that also suggests that the magma was travelling already open pathways.

    What I fear that this means that an fissure eruption is going to take place this time around. But it is hard to be sure on that until it actually happens.

  24. Diana Barnes says:

    Interesting earthquake cluster under the sea on the Reykjanes Ridge. I found this little snippet from this document

    C o n n e c t s E l d e y j a r d r a n g u r ( 2 3 )
    w i t h G e i r f u g l a d r a n g u r ( 2 4 ) ,
    wh i c h i s a r o c k 1 6 n.m. o f f –
    s h o r e . ( I t w a s r e p o r t e d on
    A p r i l 1 8 , 1 9 7 2 , t h a t
    G e i r f u g l a n d r a n g u r h a d d i s a p –
    p e a r e d . N o s t a t e m e n t a n n o u n c i n g
    t h e r e d i s c o v e r y o f t h e r o c k h a s
    b e e n r e c e i v e d . ) The q u e s t i o n
    a r i s e s as t o why P o i n t 23 w a s
    d e s i g n a t e d a b a s e p o i n t when i n
    vi ew o f t h e I c e l a n d i c method o f
    d e l i m i t i n g b a s e l i n e s i t would
    seem t h a t t h e y would h a v e con-
    n e c t e d G e i r f u g l a s k e r ( 2 2 )
    d i r e c t l y t o G e i r f u g l a d r a n g u r

    This rock disappeared? A mystery! Does anyone have any more knowledge of this?

    Ms Hekla is a real attention seeker today! I read and watch with great interest. I hold the well being of all in her shadow utmost in my thoughts especially Irpsit. No matter that people learn to live side by side with volcanoes it must still be a worry when something is not “Normal” for that area. Judging from Hekla’s past I am impressed that Iceland is warned and on standby even if the eruption comes many months or years from now. At least this country takes warnings seriously and uses IT to full advantage to look after her people.
    @ Jon
    Many thanks for your dedication too.

  25. Renato Rio says:

    In case a fissure erupts far away from the volcanic edifice the RUV webcam will not be of much help.
    And I think you guys should stay away from the endangered areas…

  26. I am going to post more updates later tonight. After little bit of rest after the work day.

  27. Irpsit says:

    I am going to say my word on volcanoes about when you live in Iceland. Me or anyone living around 50km from Hekla does not have plans about that eruption, or any fear about it. Generally, eruptions as large as the VEI4 27km high in 1947 did not produce significant damage in this populated region. So, we don’t care about Hekla. Of course there is always a small fear involved, but my fear of a 6.0 earthquake is far greater, as is for the natives here.

    Katla is another story, because the eruptions have been often massive, and with large ash fall. As for the population of Vík located at the bottom of Katla, yes, they fear Katla and they have an evacuation plan.

    In case of Eyjafjallajokull and Grimsvotn, people were catch surprise by the large eruptions, and people generally even stay with the volcanic night, as if it would be a snowstorm.

    • david says:

      Your post is really interesting to read! What do you and the people living near Hekla belive is going to happen? I dont live in Iceland ( I live in Sweden) and I still am consorned about this coming eruption and its ash clouds. I know it is a big deal there is Iceland and it has a lot of errects there.

      I read somewhere that geophysicist Pall Einarsson said that if Hekla follows its last eruptions, it would not effect flights in Europe, but I also know that you can never say what is going to happen. Hopefully Hekla wont be repiting the same air traffic chaos that we had last year. That would be terrible for the whole Europe. But I this is nature and there is nothing we can do about it.

      • Irpsit says:

        You are a bit wrong. People in Iceland are much less worried with ash than you guys in Sweden! You dont care about the ash, its just like breathing small sand. It makes your car dirty and irritates your eye and breathing. Sometimes your lungs might hurt also. Besides that, if rocks don’t fly away (and usually they only fly a couple kms close to volcano), otherwise its a scary but safe spectacle to see from far away (some 50km at least). But I still feel humble and have great respect for it. Volcanoes can kill you, from far away as happened with Laki 1783 or Hekla 1104. I try keeping a good balance between respecting it and knowing it, and being relaxed and not worrying at all!

  28. Diana Barnes says:

    @ Irpsit
    Thank you for that information. It is difficult for me to understand how it would be living in a volcanic area, as the nearest thing to anything actively volcanic in England are the hot springs in Bath, in the SW of England. I find it just as interesting watching how people react as watching “The events ” (or Lack of!). It’s also good we have you to help us get the most out of any Icelandic event with first hand accounts.

    • wurzeldave says:

      Ahh yes the Bath hot springs, the only (apparently) true geothermal spring in the UK. Bath is largely built in the mouth of a long extinct volcano, there are quite a few relics of long past volcanic activity in Somerset, Kilve beach for instance has fossilised mud vocanoes.

  29. Diana Barnes says:

    I am sorry I meant to add Jon as well as Irpsit as being so interestingly helpful. …And anyone else here who is Icelandic.

  30. RonF says:

    Boy that Pacific Plate sure is active lately. Another large one; 7.8 in the Kermadec Islands in the South Pacific. I am up at our cabin in the San Jacinto mnts very close to the San Andreas Fault so I get a little nervous being that close to the monster.

  31. Fireman says:

    50km is not so bad. I’d still be nervous of a volcano which has a track record of throwing 50cm bombs 30-40km…!


  32. wurzeldave says:

    I heard about Hekla on the lunchtime radio news here in UK, they mentioned that scientists were puzzled on the underground activity. Reykjanes Ridge looks intresting.

  33. Diana Barnes says:

    I too am watching Reykjanes Ridge. I posted something back there about the area.
    Thank you also for your interesting info about Bath and Kilve beach.
    @ Everyone
    Does anyone with more knowledge have any comments to make about Reykjanes Ridge? I saw that the ‘quakes are tectonic. What would the precursors an under sea eruption be? Could tectonic activity like this be a trigger for eruptions on the mainland?

  34. Cathy says:


    on your helicorder (the one at the bottom of the page), I think that I can see 2 decent-sized earthquakes at around 2:30PM. Is that right? And if so, would the disturbance from about 9:25PM be magma rather than earthquakes? Or wind?

    Thanks for your patience!

    • It is both. There was some car noise. But then there was an earthquake swarm in Reykjanes ridge (small one) that does show clearly on my geophone.

      • Cathy says:

        Ok, thanks. I’m learning all the time here! :)

        I suspect that there won’t be much “quiet time” over the next week or two, but if there is, I’d love to read some blog posts on how to read the various charts and graphs. Not an easy thing to explain, I know, but just what to look out for, with examples, would be a useful resource for the interested onlooker like myself.

  35. New blog post is up! :)

  36. pthalokitty says:

    Hi Jón-
    thanks so much for your blog- as an interested layperson, it is a gem of of a site to learn about the current state of Icelandic volcanoes. I am visiting soon, with the express intention of travelling to Hekla, Eyjafjallajokull, & Krafla and have a private guide tour booked. I’ve read here how Hekla may or not erupt, and that locals are not particularly worried about an event happening. As locals, though, can you advise whether a Hekla eruption is likely to affect travel to Hekla/Landmannalaugar/Porsmork/Fimmvörðuháls pass areas based on previous events? I hope you can help. Thank you!

    • Chris says:

      This is something which nobody can predict before the eruption takes place. It may be big or not, nobody knows that. Nobody expected such a violent eruption of Grímsvtön earlier this year for example…

    • Irpsit says:

      Yes, an eruption of Hekla would certainly block the road from Selfoss (or Reykjavik) to Landmannalaugar. To Thorsmork I would say so, but its a bit more further. Icelandic police plays safe side, and would close the roads close to Hekla, probably even the ring road next to Hella. I don’t know what happened road-wise in 2000, but the big explosive stage only lasted 1 day. I think they would happen the road to Landmannalaugar when eruption is effusive (to allow people to visit the eruption) but probably advise against travelling (to your own risk) and recommend great care (you never know what can happen in volcanoes).

      • pthalokitty says:

        Thanks Irpsit-
        I fundraised for 2 mths to raise $ for to get to Iceland for an artist residency, and hire a private guide to see volcanoes and lava sites for 3 days right in these areas, and want to be realistic if anything happens…

        All the best to Jon re: raising funds. Know how tough it can be!
        Do they do online crowdfunding in Iceland? If so you could try this as a means to cover your blog…

  37. pthalokitty says:

    Totally understand Chris- no one can say exactly what will happen.

    Its just hard to find info in Australia explaining what areas (and what distances from volcano) have been affected by various ash/eruptions historically and trying to factor this into any travel decisions. For example, when Grimsvotn & Eyjafjallajokull went, were the volcanoes affecting travel within 20km, 50km, 100km, or 200km radius? Was it a matter of days or weeks that travel in area was halted or did people continue to hike etc in area regardless? This info isn’t really included in the news briefs etc online…
    If you know info about this, it’d be great to hear. If it’s not something anyone knows, please let me know. Thanks.

    • Irpsit says:

      Having experienced both eruptions, here goes my reply.

      Eyjafjallajokull: ash fall occurred mostly around 10-20km around the volcano, downstream of wind. Still, you could travel by car passing through the ash cloud (to your own risk and car malfunctioning risk). Ash was only irritant to eyes and throat.

      Grimsvotn: you could see a big ash cloud just a few hours after the start of eruption. 24 hours later, we got inside the huge ash cloud and with ash fall some 200km away. Disruption was around 100km around. As quick and strong the disruption happened, as quick it went away. The land is fully green in the areas close to the volcano, with some small patches of thick ash here and there. The morning after the start of eruption, we drove there into the thick dark volcanic night. Nothing bad happened to us or our car. Eruption was visible even from Reykjavik, at its start! With our garden, the rain washed the ash away and I already ate our veggies.

  38. pthalokitty says:

    Thanks Irpsit! Very helpful information.