Posted on by Jón Frímann

Medium sized earthquake swarm in Brennisteinsfjöll volcano

Today (21-August-2017) during the night an earthquake swarm took place just east of Brennisteinsfjöll volcano. The area in question is in part inside Brennisteinsfjöll volcano fissure swarm. Part of the area is outside any known volcano. The last night earthquake swarm had some magma signature but was mostly tectonic in nature as to be expected.


The earthquake swarm as it currently appears on Icelandic Met Office earthquake map. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake in this swarm had the magnitude of 2,9 and other earthquakes are smaller in magnitude. Not every earthquake has been reviewed so far due to how many earthquakes happened. Around 210 earthquakes happened in this swarm. Around 07:00 UTC the earthquake activity mostly stopped and it has been like this for several hours. It is difficult to know for sure if a new earthquake swarm is going to start in this area soon. There is nothing suggesting that an eruption is imminent, even if magma is pushing around in the ground at the moment.

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8 Replies to “Medium sized earthquake swarm in Brennisteinsfjöll volcano”

  1. Thanks for the article, Jón. Will be interesting to see if this actvity continues.

    Also, at Austmannsbunga there have been quite a few shallow/typical EQs today. Only two have been automatically detected, but most are still missing. None of them are manually checked as of now. Between 1-2 AM drumplot shows some noise that looks like deeper actvity, but may be other signals from far off.

    http://i.imgur.com/Iq25qMT.png

  3. Looks like another Earthquake Swarm is going on slightly further to the West with a few stronger in magnitude

  4. This (what it seems) massive rifting must lead to lava reaching the surface at more places than just Holurhaun. It is definitely trying at least. I can’t remember seeing this many (during the last year) earthquake swarms spread out over different areas in Iceland in a long time, if ever.

    Is this the introduction to a much more active time at Iceland, it has been quite calm during the last hundered years.

    1. Jan, this is not a criticism. I’m just curious whether your statement about a century of calm is just a gut feeling or comes from a statistical analysis.

      1. Not statistical, but based on the small number of large eruptions during the last hundred years.

        If you look at this list and remove the small eruptions during the last hundred years (those were likely not recorded in previous centuries) you will note that the last hundred years seems to be rather quiet in comparision with the previous centuries:
        – http://icelandgeology.net/?p=765

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