Hellisheidahraun Lava

Photographer: Eggert Nordahl, all rights reserved. Notice the pipelines up to the left, and the SIL sticking out ontop of the further crater rim.

Hello Everyone!

I wish to congratulate the winners of this weeks competition. I had done a lot to the image by Eggert Nordahl. I croped it to remove the Hellisheidarvirkjun pipelines on the left of the picture, and I also croped off the Hellisheidar-SIL. Then I inverted it to further bungle up any Google Image Searches.

Map showing where the mystery lava image was taken. As you all notice it is slap bang between the various bore-holes.

So, Alan caught the surface lavas, Irpsit nicked the Grámosi and the Hengill points, and finally Spica had the Hellisheidi eruption (in Icelandic Hellisheidahraun).

While coasting around for info on Hengill I found a drill core that had been analyzed. It seems like Hengill has had not less then 5 different magma-zones. I think the weirdest would be the chloro-epidote stage. If I understand it correctly chloro-epidotes are constructed by forsterite (olivine) is quenched into a salt-brine. This phase would of course be from the time when Hengill was rather suffering from being sub-aquatic (before it rose out of the sea). I guess that Alan will let me know if I got this all wrong and in no uncertain terms.

So, to round it off, one could say that the image is from the Hellisheidarvirkjun Powerplant.

CARL

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290 thoughts on “Hellisheidahraun Lava

      • Maybe not “stronger” per se, all similar or lower values so far. We can say stronger if many go abowe previous ones, but interestingly they show up at very far stations (also the storm cancelling effects are dying). One thought I had now, is if this might happen on other side of Iceland as well, then that whould be in the highlands near Mrs. Hekla. *not expertTM*

    • Thank you. From this, it would appear that the location is a tectonic fault rather than volcanic – IF I have read the maps properly (Not an expert TM).

    • Yes, this swarm matches one of the positions in fig 12. The eqs displayed there run up to 2007 but from memory, I’d say that eqs from 2010 and on have occurred in exactly the same spots – Herdubreidartögl plus just SSW and N to NNW of Herdubreid.

  1. Well some unusual happenings in Iceland. Quite a swarm of quakes in the Askja area. Unfortunately some SILs are not working.
    http://en.vedur.is/earthquakes-and-volcanism/earthquakes/vatnajokull/

    South of Katla I think maybe there has been maybe a small glacier flood which has caused this pattern at Eystri – Skogar

    The river Markarfljot was running very high but has rapidly decreased in depth. Unfortunately I have no access to any other readings relating to this.
    http://en.vedur.is/#tab=vatnafar

    • Yes, last 30 min have been very active. They show up on many SILs (even them in s-w Iceland) and likely show in next few updates on IMO main charts.

    • Likely never. And that is plain wrong doing for the people in El Hierro. I simply wonder what goes on in the minds or heads of such people. Likely answer is “nothing” (like broken, out of order, Kaputt etc.)

    • Conclusion is interesting: “In this scientific work also indicates that, according to the seismic signals in recent years, the probability of a process of reactivation of Teide volcano is considered low.”

      • This is an interesting announcement…
        From the Renewable Energy people…
        Not PEVOLCA… 😀

  2. Carl, you have Henri le Revenant mail. (Ref the May 14, 2012 at 12:01 post)

    Lacking additional specs, I had to wing it.

    • Thank you Renato. Well, does not surprize me! I did mention danger of side/cone collapses in one or more posts on El Hierro bob (back at Jóns Fr blog I think)

    • Thanks Renato. It is a very interesting post. What really bugs me is the loss of opportunity for a really intense study of a submarine eruption from beginning to “end”, even though Bob was possibly just a vent off the main volcano.
      Maybe there were many scientific people on El Hierro collecting data but I just got the impression that it was all ad hoc and the boats were only press-ganged when activity appeared worrying.
      For anyone interested this link gives lots of info. on Axial Seamount off the west coast of USA and how scientists go about studying undersea eruptions.
      http://interactiveoceans.washington.edu/story/Axial+Seamount

    • Hmm…

      Wasn’t Bob basaltic and doesn’t Eric point out that you need at least andesitic magma in order to produce domes or spires?

      :confused:

  3. The weather seems calmer on Iceland today – but Hekla is still quite angry. Is this weather, or ‘Herdubreid’, related? Or is she doing her own thing? 🙂

    • And now ‘Habunga’ is tap dancing and there are two largish quakes on USGS at the Reykjanes Ridge.

  4. In the paper linked by Peter earlier, http://www.raunvis.hi.is/~astahj/msritgerd.pdf there is a definition on p.52 that is very interesting:

    “A volcano is defined as a central volcano when it fulfills several criteria‟s [Johnson, 1989; Walker, 1993]. Central volcanoes are shield volcanoes or stratovolcanoes. They have a significant amount of silicic volcanic rocks in addition to basalts, while rocks intermediate in composition are scarce or absent. Central volcanoes often have one or more calderas that have resulted from subsidence after large silicic eruptions [Walker, 1993]. The concept of volcanic systems is used to acknowledge that the visible edifice of a volcano is only a part of a bigger entity. This concept includes the magma chambers, conduits, magma source, intrusions, geothermal fields as well as the volcano itself [Walker, 1993]. It also includes the associated rift zone.”

    Anyone else see what’s wrong with this definition?

    • Ummm – does that mean you can only have one volcano on a rift zone? Also the sencond to last sentence should perhaps say “as well as the visible part of the volcano itself” or somesuch. (Don’t forget I know nothing!) 🙂

    • Surely a rift zone is tectonic not magmatic?
      A central volcano may not have a Caldera… I don’t think Mt St Helens has one for a start!.. However we are back to the definition of what exactly is a caldera. I personally understand a caldera as having a diameter over half a Km wide and of low elevation formed when the majority of the volcano collapses into an emptied magma chamber, Anything smaller and of a higher elevation is a crater, even if it has a dome inside.
      Is this definition saying that a central volcano only has both basalt AND silicic rocks? Hmmm! A messy definition.

    • Clues:

      * The semantic content of the word “Central”?
      * What kind of lavas do volcanoes such as Etna, Fuji and Hekla erupt?
      * Ditto Pelée, Martinique, or Sofrière Hills, Montserrat?
      * What of the Three Sisters, Orgeon?

      PS. Semantically you are correct Talla, but it’s not what I reacted to, at least not primarily.

      • Addendum:

        * South America, The Andes, Andesite… …“while rocks intermediate in composition are scarce or absent

  5. Three earthquakes now the last one|;

    mb 4.8 Region REYKJANES RIDGE Date time 2012-05-15 07:16:20.0 UTC Location 59.86 N ; 29.85 W Depth 40 km

  6. earthquake2012-05-15 07:16:16.0
    2hr 16min ago 59.82 N 29.85 W 10 mb 4.8 REYKJANES RIDGE 2012-05-15 09:13

    earthquake2012-05-15 06:45:30.0
    2hr 47min ago 59.75 N 29.82 W 10 mb 4.6 REYKJANES RIDGE 2012-05-15 09:12
    earthquake2012-05-15 06:31:32.0
    3hr 01min ago 59.78 N 29.84 W 10 mb 4.5 REYKJANES RIDGE

    • As we have noticed prior to the Herdubreid rash, the last few days have been quiet and that always presages an outbreak of earthquakes on the MAR (cart before the horse, or…?).

      • I do not entirely agree with this, this time, and a few others, the quake signals have been suppresed by regular Icelandic weather.

  7. A word abote the earthquakes in Katla this morning – look at the depth! All five checked by the IMO (out of a total of seven) are extremely shallow – 0.0 to 0.1 km – hence not magmatic but hydrothermal. Think Geysir, or more accurately, Strokkur!

      • I do not know, but I would not be surprised if it turns out a new pit has formed or is forming in the glacier and the quakes are from ice falling down in its creation.

        • If this is the case, checking the out flow of the local rivers should tell. I agree Henri, hydrothermal, If it was take powerful to dent the ice sheet, would we not see more EQ’s and a 3+ too?

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