Krafla – Iceland’s divorce volcano

Photograph by Michael Ryan, USGS. Picture showing the 1984 eruption.

When I was a child I grew up with Krafla. Not so odd perhaps since it erupted for nine years. In my childhood mind it seemed like Krafla divided Iceland in two parts, and I dreamt up weird bridges spanning the fire fountains that in my dreams spanned the entire length of the island. Come to think about it, no wonder I became both a volcanoholic and Icelandophiliac when I grew up.

Kraflas diverse mechanics

Krafla is considered to be a caldera volcano, and a complicated one to boot. It is actually a double caldera volcano where the outer caldera is visible, and the inner one is filled up with lava-fields. The calderas are in turn dissected in a north-south direction by the Eastern Icelandic Rifting Zone and in the east-west direction by a transverse Graben. On top of that there is a northern fissure zone extending out to the ocean, and a southern extending to Lake Mývatn. So, it is quite easy to discuss activity as being in one of the quarters of Krafla. The latest eruption was in the northwest quarter.

Photograph by Michael Ryan, USGS. Picture is showing what might be the closest resemblance to what Mordor looked like… 1984 eruption.

Already one starts to understand that this is a very odd volcano. It is actually rather hard to say what type of volcano it is. It is a rifting fissure volcano, but with a magma chamber that is large enough to actually be able to building up enough to collapse. It can have central caldera eruptions like the latest, and it can also have fissure eruptions. It is also able to have crater and cone formative eruptions, as it did 1300 when it had a crater eruption south of Viti.

Krafla normally erupts alternating to the north or south of the transverse Graben. Of course this does not go like a pendulum, but in general it never erupts both to the north and the south. The transverse Graben also has the effect that any tremoring in the north half will only show up on the north SIL-station, and activity in the South will show on the south SIL only. In this capacity the Graben functions as an imperfect sound-shield.

Photograph by Michael Ryan, USGS. Even though the scale of the lavaflood is immense, we should remember that this is a very small rifting eruption. Please notice the researchers up in the front to get the scale. Eruption of 1984.

Normally Krafla has rather unexplosive eruptions, but there have been a couple of confirmed VEI-4 eruptions, and the Viti formation was probably a bit messy. Another feature of Krafla is that it normally erupts in intervals that are loosely based around 230 year cycles. This is associated with increases in the rifting in the North Icelandic Rift Zone. Sometimes it seems to jump over 1 or more of the rift cycles, and sometimes it seems to disregard the rifting totally.

According to IMO Krafla will not erupt again during this current cycle of high rifting in Iceland. There is a bit of a debate if the current cycle started with the 1960 eruption of Askja, or with the eruptive sequence of Krafla. Be that as it may, we are definitely closing in on the high-point of the current rifting cycle.

Kraflas latest eruption

The rifting of Iceland goes in intervals where the rifting is sometimes slower than the annual average 2.5cm, and sometimes faster, even up to 5cm annually. But on average it rifts at that speed. These episodes of high rifting normally correspond to Kraflas eruptive cycles.

Photograph by Gudmundar Sigvaldason, Nordic Volcanological Institute. Anybody up for lava hoolahoops? Eruption of 1980.

1975 Krafla started her latest eruptive cycle, up until 1984 she had no less than 6 eruptions. The eruptive fissures started to the west and ran in roughly north/south direction, and then each new fissure eruption moved towards the north and east. Each new fissure generally erupted more material than the previous.

The site of the eruptions was trending from Leihrnjúkur to the north. There is still activity at Leihrnjúkur with intermittent small earthquake swarms and occasional harmonic tremoring. So the area is in no way really dormant. Leihrnjúkur is situated roughly 1.6 kilometers NNW of the Krafla Geothermal Power plant which was being constructed during the initial eruption. One can easily understand that they were a bit nervous about that back then. Especially when a likely fissure opened close to the bottom of one of the boreholes and fire started to sprout forth out of the tube sticking up out of the ground. This was probably the first and only manmade volcanic vent in history.

Today there is a very low probability of Krafla erupting, even though one should never say never about any Icelandic volcano. Remember the earthquake swarms, and the occasional little spasm of harmonic tremor in the northwest quarter.

Krafla Inflation

During the Krafla eruption something odd was noticed, and that is that Askja deflated prior to the eruption of Krafla. This deflation of Askja continued up until just a few years ago, and when Askja started to inflate, Krafla in turn started to deflate. There is probably no direct magmatic link in between them. But there might be a deeper relationship at the feeder level down at the MOHO.

Photograph from the 1980 eruption by Gudmundar Sigvaldason, Nordic Volcanological Institute. The image as lava is falling as a waterfall into one of its own fissures makes one wonder… Does volcanoes regurgitate and ruminate upon their own lava?

A fun fact is that during the eruption the IMO used one of the simplest tools to measure a volcano ever deployed. They used a water filled device to measure how the water level was rising and sinking at the ends. By using what is in practice a very long aquarium they got a very good inclinometer showing how the angle of the volcano shifted. A lot of data was gleaned through this very simple device. Never ever short sell simple things; they are often giving the best and most reliable data. Well, as long as you remember to pour in new water from time to time.

Ah… The title. I should perhaps explain that. I am of course talking about the divorce between the American plate and the Eurasian plate. As the plates move apart, the poor child of Krafla gets cranky.



665 thoughts on “Krafla – Iceland’s divorce volcano

  1. ULPGC scientists prove that life has returned to the Mar de Las Calmas but the focus remains active


    Scientists at the University of Las Palmas de Gran Canaria, aboard the research vessel chartered by the university to campaign in the Sea of ​​Calm (El Hierro) have been filmed by a robot submarine vessel Atlantic Explorer the submarine volcanic cone and was the first camera that sits on the cone of the volcano.

    Scientists say there is no tremor in the water, but you can see a “shower of stars glowing” in the mouth of the volcano, as the focus volcano remains active, which has been sampled over 60 º C temperature of water. In the area have also been shown that marine life has come back near the volcano.

    The campaign, called 2-ULPGC Guayota, involved researchers from GEOVOL (Land Group Volcanic Geology), the Division of Robotics and Computational Oceanography (IUSIANI University Institute of Intelligent Systems and Numerical Applications in Engineering) and IOCAG (Institute College of Oceanography and Global Change) – all of ULPGC – and it collaborate the Jaume Almera Institute (CSIC) and the Oceanographic Centre of Canary (IEO).

    The campaign takes place aboard the R / V Atlantic Explorer (QSTAR SLU) for the study of underwater volcano of El Hierro and oceanographic involvement as well as observation and filming of the volcanic cone.

    The first results of the images have been recorded are:

    – For the first time have obtained images of the new undersea volcano appeared near La Restinga (El Hierro), at its southwestern flank and near the crater area (to 172 m)

    – In both missions have shown that the main focus continues still active volcanic

    – Emerging from depths of about 120 m, shows the formation of convective hot jets reaching depths of about 40-60 m. At the outlet of September 13, the ROV entered one of them and made several turns uncontrolled, while the sensor temperature increased sharply

    – Also from the same depths are generated pyroclastic projections about 40-50 m in height (ie the pyroclasts reach depths of 80-70 m), which rapidly form ballistic trajectories (parabolic) and fall under gravity. Some of these pyroclastic seem to be large (type volcanic bombs)

    – During the dive on Wednesday, 14 came to film the southwest flank of the main cone, putting on shows that have a steep slope and is formed mainly by large pyroclastic, some of which are similar to volcanic bombs hollow reaching the surface in the months of November and December

    – Finally, near the edge, at a depth of about 170m and under a rain of ash, had a school of fish (amberjack possibly) living with the volcano. Also confused with the ashes is observed and many small bodies and, closer to the surface, jellyfish.

    The University of Las Palmas de Gran Canaria chartered a boat to facilitate scientific research in the sea of ​​Restinga (El Hierro), in the area where the submarine volcano.

    The Vice President for Research, Development and Innovation ULPGC, directed by Fernando Real, has coordinated the rental of the vessel Atlantic Explorer QStar the company, who will perform 7 research cruises in three and a half months, from February 17 . The investigations are conducted by scientists from the Departments of Biology, Physics and Chemistry of the University Institutes of Oceanography and Global Change (IOCAG), Intelligent Systems and Numerical Applications in Engineering (SIANI) and Animal Health (IUSA), the Spanish Bank of Algae and research groups in Biological Oceanography, Physics and Satellite, Marine Chemistry, Robotics, Marine Ecology and Fisheries and geology, among others.

    video soutwest side of the main cone

    fishes swiming near volcano.


    • AAAAAAAAAAAaaaaahouhouhouhouuuuuuuuuu… Oooooohnoooooooo now youhouhouhouuuuu are baaaaaack. Baaaaaaahahahahououuuuuuuu… My nuuuuumber fiiiiiiiiiiiiiiiive…
      Hola hombre.

      • And you took my beginning of the page bad joke place.
        I know where Spain is, I’ll get you one day… 😉

    • Welcome back CarlosB!

      And for those who wonder after the last days discussion on how to post.
      This is how I like it done.
      1. First a summaric sentence.
      2. The copied text clearly attritbuted.
      3. Link to original source.

      It does not need more. Very pedagogic of CarlosB really 🙂

    • Many thanks for translation Carlos B. !
      I had just found the spanish link on Earthquake Report.
      Now just to have a look …

    • Hey Carlos welcome back. We now have proof that Bob is very much alive. I am not sure if it is my computer or not, but I can’t get the video links to work right. Is anyone else having trouble?

  2. So Bob not yet dead ! Sturdy little volcano. HIp hip hip hooray for Bob !
    I am wondering at the lack of tremor on the seismogramms. How can it be so. Is it because the lava flow is too low ? I know that the range of the equipement has been narrowed a lot and that the signal is very dampened, but I wonder.

    • @ dfmorvan

      Someone will no doubt correct me (please feel free!) but I believe this is because the magma is now free-flowing but also under a weight of water. I would expect to see this. A bit like being squeezed out of a tube rather than splatted out of a bottle! It is still under water but running in a more gentle fashion than it would be if it were to break the surface and become surtseyan and explosive. Rooster tails will be quite a different thing to watch on seismograph and webcam.

  3. Hola amigo GeoLoco… hahaha

    i am back but i need to care of my love…
    On october 25 years married+6 years friends…
    Each day she is more beautiful, pretty and sexy…
    I need time for her.

    And I havent any beer yet…
    must be the spring? hahaha

    I think I let you win the 5. hahaha

  4. Evening fellow Lambs!
    @ Carl –
    I am unable to mail to your ‘other’ site – “relay access denied”
    Very private (!) Is there an alternative please – private reply
    Thanks Alan

    • Hello!

      I am still having a bit of a problem with that one. Just write to the one here for the time being.
      Hope that the trip was nice!

  5. Totally off topic, but totally The Earth…
    To those interested, use full screen and adjust the sound to nearly maximum and enjoy …What a fantastic world this is!

    PS, I promise you to be more “on topic” when Iceland decide to grow a little more…or less 😉

    • ‎”From this vantage…we see our own civilization, echoing back the energy in the universe, we glow, as if we are one unified organism…”

      Fantastic words

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