Posted on by Jón Frímann

Old rift zone in Iceland

Here are two pictures of an old rift zone in Iceland. This rift zone was active until about 7 million years ago or so. This cliffs that I show here on this picture are from this old rift zone. It was volcanic long time ago. But not any more. This area however holds an good amount of unknown fissures and fault lines that might become active one day and create earthquakes in this area. But the years that I have been in this area I have never felt an earthquake. But I have recorded earthquake somewhere in this area. But it was an minor one. Less then ML1.5 in size. This area also used to be under ocean for several million years before it became dry land.


This is the old rift zone that was active until 7 million years ago. Click on the picture for full size. This picture is released under Creative Commons Licence. See the licence page for more details.

There is still an chance of this area to get new volcanoes in far future. Like did happen on Snæfellsnes. But this rift zone did pass trough there also. In this old rift zones there are several old volcanoes. I have covered them before on this blog. But that blog post can be found here.

More articles on this area

The Iceland Hotspot (academic.emporia.edu)
Iceland 2003 Keck Junior Research Project Geology of an Abandoned Oceanic Rift: The Skagi Area, North-Central Iceland (people.usd.edu)

25 Replies to “Old rift zone in Iceland”

  1. Speaking of rift zones, I was actually looking into them today, more specifically a “new” one, the eastern rift zone in Iceland and it’s activity south of Katla.

    I’m wondering if the Eyjafjallajökull eruption may have marked a start of increased drift in the area.

  4. There seems to be something going on in Katla volcano. What I am not sure of yet. But there is an harmonic tremor spike that looks like an eruption or possible an glacier flood spike. What this exactly is going to be come clear in few hours. I am going write about it when I know more about what is going on.

  5. Dear Jón,

    Regularly I have seen very small negative quakes at great depth at Katla (-0,1 at a depth of 24 km, tuesday and -0,2 at a depth of13,8 km, today).
    I’ve learned on this blog (I think it was Pieter who explained it to me) that it’s possible that negative quakes exist, but what happens deep down when those negative quakes occur? What causes it?
    I appreciate your answer!
    The small quakes of this morning are widely spread, interesting! I’m curious for your updates!

    Kind regards,

    Henk Weijerstrass
    Holland

    1. The scale which is used for the earthquakes is logarithmic. So very small quakes get a negative value because of that.

  8. Deep earthquakes is what we should expect before an eruption. I always said that no large eruption would occur in Katla without those deep earthquakes.

    Now we see harmonic tremor and deep earthquakes, this marks the push of magma upwards from the mantle into the chamber, until the pressure does not hold anymore. I think we are now much closer to the expected large eruption of Katla but for how long this will continue I don’t know, but it can be something between 2 months to some years. I still think this entrance of deep magma to continue for at least a few more months, with larger deep earthquakes.

    Expect of course larger shallow earthquakes just before the eruption.

    1. My bet is that Katla might erupt this next summer. Let’s see what happens during the summer season. It can still be a repeat of 2011, and an eruption only happen a few years later. Volcanoes are of course difficult to predict.

  9. The wind noise is too high so I can say what might be going on. But I there is an possibly of an minor dike intrusion in Katla volcano during the night. But this is unclear at the moment.

      1. ~1/2 of the stations are from the University (better maintainance)
        ~1/2 of the stations from the IMO, lesser maintainance if any during winter, the stations that are not sending signals are theirs.

        What you can look at is here http://strokkur.raunvis.hi.is/~sigrun/KATLA.html Fimmvörðuhals & Rjúpnafell is updated, Lágu-Hvolar data is fairly recent.

  12. I dont think they update them! I’ve been trying to get gps and profile data for a while. The whole level of activity all along the fault in Iceland and the sea seems to be unerringly on the increase, and the quality of this data seems high. I dont personally think we will be waiting until summer for activity showing itself. I do think rift zones will open up at the same time as any volcanic activity as the stresses on the land mass has to be incredibly high – given the length of time without major eruptions.

    Call me cynical, I just cannot accept the next chapter as being katla alone!

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