Herðubreið – Renewed activity at Askja

Photograph by Zanthia. On the picture one can see Mount Herðubreið. Herðubreið (Broad Sholder) is a tabletop mountain, or in another word, a Thuya.

Yesterday an earthquake swarm started with a 3.4M earthquake at Herðubreið. So far the swarm has had 15 earthquakes above 2M, among those 3 where at Askja proper. This swarm as well as the previous ones at Herðubreið have been to the west of the volcano. And those earthquake swarms have been deemed to be lateral intrusions from Askja.

Image by Icelandic Met Office (IMO). Askja to the left of the green star, the black “circle” above is Frémrinamúr. Kverkfjöll is due south and not showing here.

Image by Icelandic Met Office (IMO).

Only problem here is the 3 earthquakes that happened within Dyngjufjöll (Askja). Having 3 earthquakes above 2M at the same time as a medium sized earthquake swarm takes place rather beggers coincidence. I think when the hubbub of this is over the area will be removed from Kverkfjölls fissure swarm. One should also remember that Kverkfjöll is the smallest volcano on the riftline.

Image by Icelandic Met Office (IMO). There seems to be magmatic components to the earthquake swarm when looking at a higher resolution.

On the other hand, this is as far as known not anywhere near any part of Askjas fissure system. We should remember that. Personally I thought up untill now that Herðubreið itself belonged to the Frémrinamúr volcanic fissure swarm. Apparantly I was as wrong about that as the ones who thought it belonged to Kverkfjöll.

Image by Icelandic Met Office (IMO). The earthquake swarm shows well also at the Dyngjufjöll SIL-station.

So, now we are back to a long dormant volcano that had it’s last eruption before deglaciation. And that put it as having erupted at 6000BC latest (time when the glacier withdrew). How do we know that? Thuyas only form under glaciers that are big enough to contain the erupted lava thusly forming the tell-tale tabletop look of a thuya. So, we are talking about a long dormant volcano here.

Image by University of Iceland and Professor Sigrún Hréinsdottir. Inflation showing at Askja. The inflation at Herðubreið started 2 years before.

If we look at the 12 +2M earthquakes we find that 9 of those are between 2.2 and 7.9 kilometres deep. 2 of them are 1.1km deep, and that is a dummy value when an actuall depth has not been set, then we have the original 3.4M quake that has a suspiciously undeep figure. The current given depth is almost certainly around 5 to 7km and will be revised sooner or later. What does this then tell us? That the figures point towards a magmatic intrusion into an old chamber. Remember, this is my interpretation.

So, back to Herðubreið. What is Herðubreið? In my eyes Herðubreið is starting to look like a volcano on it’s own. One of the reasons is that it started to inflate just to the east before Askja started to inflate. It in fact started inflating and having earthquake swarms to the east before Askja stoped deflating. So, I am actually contemplating that Herðubreið and Askja had a common origin and has been rifted apart by the EISZ part of the MAR over the course of millenia. What I am trying to say is that they might actually share a deep root found in the current EISZ. We could think of them as two non-twins sharing the same womb and umbilical cord.

Untill we have new data from the area this is a bit speculative, but I do not think it is that much way off.

CARL

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299 thoughts on “Herðubreið – Renewed activity at Askja

  1. Thursday
    17.05.2012 18:46:52 65.151 -16.443 2.0 km 2.5 90.04 5.1 km WSW of Herðubreið

  2. Irpsit et all:
    Many thanks for the Icelandic guided tour.
    I crossed Patagonia when I was younger, but nothing comparable to Iceland, as it sounds.
    But also a desert, no gas stations, strong winds and sand storms.
    Still Iceland beats it, I imagine. :)

    • For them not used to Icelandic weather, only that can be adventure. But as it goes, if anything happens, I for one know (most often) what to do or not to do. Rule number ONE, make plan and stick to it, if car breaks down, stay with car. In summer, one can call for help (several alternatives) or wait for next traveller for assistance/lift out.

      • I would think that having a set of boating flares along would be handy in winter.

        • Yes, useless in snowstorm/rainstorm, only in clear weather and such is rare in the highlands in winter, ok for summer in clear weather. Most 4×4 off-road trucks or buses have mobile and / or radio for mayday calls. In fact almost everybody here have moblie phones and know where to call. As ex- of a SAR team, I know, been there, done that, and done a few searches. Have “First-Aid 101″ etc. etc..

      • - and know where your vehicle’s inertia cut-out switch is, so you can reset it after hitting a big bump.

        • one trick in old days was to dip nose into the stream before crossing a river, to wet the fan belt on the crank, and thus lessen fan gushing water all over the engine. Todays many cars have electric fans only, but always cross rather slower than faster for same reason.

          • Ok. Extreme case! Do not recommend this, or crossing a glacial river that deep, but car seemed capable of handling it (in the end, but it seemed close shave). No further comments, please!

        • Not really gonna apply to most vehicles, but on Ford’s Ranger series it’s on the firewall on the passenger side… up by the knees on the inside.

    • In regard to the inaccessibility of the Herðubreið area, if an eruption were to occur there it would hardly be a tourist event, and it seems that it would be difficult if not impossible for the media to cover it, except from the air. And since we all prefer eruptions with webcams focused on them, there would definitely be some frustration here. :cry:

      On the other hand, being so far from populated areas, an eruption should not pose much danger to the Icelandic people, except perhaps from an ash cloud. Or would there be other factors to consider?

    • “Marked” is misunderstanding purpose, this is IMO site for “quick seeing” of all larger quakes. Coloured squares on the maps are where SIL stations are located, that have picked up the quake in question are located (“colour code” per bars alongside).
      This (below) is same page index, but I do not use this link when major events happen, as it possibly can load IMO internal systems, and that use is better reserved for specialists and rescue services. Ok? http://hraun.vedur.is/ja/alert/2012/may/17/index.html

      • Thank you for this comment Islander. I can see it is not good of me to use these links.
        I would not like to cause any interference. I did not think. It will not happen again.

        • Ok. Diana, maybe I was too harsh. Sorry for this. Suppose some use is ok on normal days, its open source and part of IMO / EU warning systems. I only do not know how this is run and before I know everything I mark this as “innards” of IMO and do not use it when there are emergencyes or when other parts seem under lots of load.

          • Any idea how to extract specific phase data from it? (S-P)

            Is there a data spec page somewhere?

          • Hey Islander. No Worries. I agree with you 100%. It may be a good idea if readers are aware of sites that are used by emergency services. Maybe a post about how warning and emergency services work, not just Iceland maybe. Then readers can be made aware of how the impact of heavy footfall on pages can impede essential work. This may be useful during the first stages of eruptions.
            I think it essential Volcancafe should be seen as a serious and responsible site….even though we have our “silly” moments.

          • @islander and Diana
            Carl is checking through the link collection i am gathering from time to time, if there are such links which should be reserved for emergency only so those lines wont be overloaded with layman who dont really need the data. But please take a look yourself, of course i will remove all links which should not be there. The links are up in the menu in our treasury

    • Is Grábrok by any chance home to the Graboids? That would certainly explain the anomalous earthquake.

      • Certainly the name sounds as though it was once infested by them. There might be a small colony left there while the main group moved west.

        • There’s 3 cinder cones along a short 3/4km fissuer from about 3000 years ago, 2 breached by aa lava flows – Grabrok was my first volcano ….aaah!! :-)

        • *Should have said they moved east!

          @Alan: Did you actually go to visit it, or was it studied from afar?

          • Talla
            International Scouts & Guides Jamboree, Hredavatn July 19*6 in a grassy enclave within the aa lavas – acted as a superb barrier between scouts and guides!!!! I’ve a spindle bomb from Grabrok in my map room!

  3. Very interesting article over at Eruptions about volcanic lightning. http://www.wired.com/wiredscience/2012/05/examining-volcanic-lightning-during-explosive-eruptions/#more-111070
    And marc burns posted a comment with a link to a site where it is discussed that earthquakes seem to create a signal or a disturbance in the ULF radio band in advance
    “Earthquake Alarm
    Impending earthquakes have been sending us warning signals–and people are starting to listen”

    http://spectrum.ieee.org/computing/hardware/earthquake-alarm/0

    • What exciting information. I have no doubt soon there will be earthquake alerts. What a blessing that will be. Despite the world financial crisis I do hope governments will readily spend on research such as this.

      Volcanic lightning is also interesting and as mentioned could be a useful warning of an eruption in progress in unpopulated areas. This especially for aircraft.
      I was amazed to see some small lightning bolts a few weeks ago when I was watching Sakurajima. There was a sudden explosive belch and lightning was produced above the crater.

      • Explosions on Sakurajima are preceded by increased activity in the local birds and increased fumerole activity near or in the crater. Unfortunately the timelapse between the birds getting more agitated and the explosion is not very long so less effective as a warning.

    • Redoubt was my first volcano “watch”. Unfortunately, I missed seeing the lightning event shown on Eruptions because it happened late at night. The Alaska Volcano Observatory has a very large collection of images and the following link shows more of the lightning event. If interested, there are several pages of photos before, during and after the eruption.

      http://www.avo.alaska.edu/images/image_search_results.php?volcano=ak231&year%5B%5D=&type=&caption=&lastname=&firstname=&recent=&limit=50&page=17

  4. During research for an article, I came across this:

    Television filming sparks eruption fears. The Iceland Review reported that, in the early morning of 9 December, the Icelandic emergency hotline received calls from residents reporting bright lights on the slopes of Mýrdalsjökull. Callers feared that an eruption had started at Katla. The bright lights had also been noticed on a webcam by observers in Norway, who also enquired if there was an eruption. When the glacial slopes were inspected to find the cause of the lights, it was discovered that they were from film crews for the HBO series “Game of Thrones”, who were filming in the early morning to capture the desired light conditions.

    http://www.volcano.si.edu/world/volcano.cfm?vnum=1702-03=&volpage=var

    Bloody H, isn’t it hard enough as it is without HBO deliberatly trying to mislead us poor volcanophiles? ;)

    • I think (IIRC) someone here actually spotted those particular lights on that night as well and there was guessing going on as to what it could have been. So it wasn’t just observers in Norway, also observers in volcanocafe. :-)

      • @Henri and Ursula: I just checked back and it was Diana who spotted the lights, and quickly discovered that it was Game of Thrones being filmed so no panic here, just interest. :-)

        • Ah, another feather in the hat for the so aptly named Diana!
          (Seriously, I’m impressed by that piece of sleuthing. Shame the GVP doesn’t credit her for it.)

  5. Next lava will be up at 16.00 CBT (Central Blog Time).

    And to the utmost joy there will also be a new riddle from Alan, so be prepared.
    I had to glue on old Pentium-fans to my head to cool down the brain while trying to solve it… I still got nowhere :mrgreen:

  6. Since this thread is no longer the leading topic thread…

    Data for KarenZ

    On that cross section plot that I did of Herðubreið, here is the terrain data for it.

    Longitude vs Height (m). This goes E-W right across the top of it to the other side of the plate boundary. Filter out what you don’t need.

    For everyone else… sorry about the data drop.

    X Y
    -16.155726 , 567.4542236
    -16.16463233 , 558.4138794
    -16.17353869 , 543.7531738
    -16.18244509 , 532.7614746
    -16.19135153 , 493.0849609
    -16.20025799 , 477.3357239
    -16.20916449 , 480
    -16.21807103 , 484.277832
    -16.22697759 , 490.7168579
    -16.23588419 , 496.5530701
    -16.24479082 , 504.0666199
    -16.25369749 , 511.5781555
    -16.26260418 , 515.3479004
    -16.27151091 , 517.2810669
    -16.28041766 , 519.2149658
    -16.28932445 , 564.1263428
    -16.29823127 , 710.03125
    -16.30713811 , 895.9356079
    -16.31604499 , 1198.60376
    -16.32495189 , 1450.217896
    -16.33385882 , 1520.277466
    -16.34276578 , 1536.527344
    -16.35167277 , 1492.496338
    -16.36057979 , 1446.679321
    -16.36948683 , 1318.179688
    -16.3783939 , 993.5599976
    -16.387301 , 795.2661133
    -16.39620812 , 686.5962524
    -16.40511527 , 657.7792969
    -16.41402244 , 656.684082
    -16.42292964 , 655.737915
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    -16.44074411 , 663.4121704
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    -16.467466 , 702.4833374
    -16.47637334 , 709.0648804
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    -16.52091038 , 720.5577393
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    -16.56544793 , 741
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    -16.79704987 , 599.555542
    -16.80595781 , 579
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    -16.83268168 , 608.3927002
    -16.84158965 , 617.6119385
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    -16.87722162 , 608.2686768
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    -16.90394567 , 566.4206543
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    -16.93066977 , 537.4261475
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    -16.96630196 , 574.8040771
    -16.97521002 , 600
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    -17.0821068 , 580
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    -17.12664709 , 598.046814
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    -17.1711873 , 558.3279419
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