Posted on by Jón Frímann

Large earthquake swarm at Herðubreið

A earthquake swarm that started out small earlier today has grown and is now a earthquake swarm with considerable size. According to automatic data from IMO and the SIL network the largest earthquakes have reached ML2.2 in size.

This area is known for a lot of earthquake activity. So this swarm is not a surprise. But this type of activity happens regularly in this area.

17 Replies to “Large earthquake swarm at Herðubreið”

    1. Yes, this was still human noise. The geophone can see a car driving by up to 15 km away on a road nearby. So expect this type of noise to happen regularly. Mostly on weekends during the winter and on many days during the summer.

      The human noise is however going to be different between geophones due to location.

  5. Personally… I can’t say one way or the other. But I would think that if it were magma it would have a direction to go, and you might be able to follow it’s path via the quakes.

    This seems to have started at about 10 km depth and propagated both up and down.

    http://i55.tinypic.com/1zvshup.png

  8. I don’t know what to make of this. Looking at the IMO map for Mývatn, the quakes are oriented on a SSE to NNE line, which agrees with the orientation of the Eastern Icelandic rift. Looking at Lurking’s graph however, if one subscribes to the rift, would argue breakage or slippage at three distinct point. Could it be a combination of magma intrusions and rift opening?

  9. Well, they are on a plane, it’s just that the view I selected points out that there were three distinct areas making noise at the time. The main group that got our attention is the one that drops down as far as ≈13-14 km. It’s definitely on a SSE to NNE trend.

    I’m thinking that the other two groups are there because the main group is making noise. Sort of like dogs barking. One sets off the neighborhood. (except for that one last night. I know the guy over on the other side of the field has about 5 dogs. Just one was barking for about 3 hours. The rest were quiet. Also quiet were his peacocks and the coyote pack that lives down by the river.)

  10. Since I find Herdubreid and Herdubreidartögl a mystery I have read up as well as possible on it.
    I will summarize it shortly.
    Both volcanos are in the Askja volcanic system according to GVP and they have a fairly recent activity record with eruption taking place during later stages of the last ice-age when they where under Vatnajökull glacier. Those eruptions are tephracronolised to have been taking place 14000 – 8000 years ago. So it is in a geological perspective not a long time since last activity. Askja itself have had rifting eruptions trending towards that area later than that.

    The sum of the quakes can be divided into 3 groups. One shallow that is tectonic in nature occuring at shallow depths, 2 – 7 kilometres. From 2005 there is one set of deep crustal quakes with a different wave-signature believed to be caused by magmatic movement/intrusion between 34 – 15 km. From late 2009 a third set have evolved with quakes that show signs of being both magmatic and tectonic in wave-forms between 15 – 8 km.
    The last group is according to Lurkings plots moving up and down all the time without a clear progression that is the telltale sign of magmatic movement up a reservoir. My theory on that one after having scratched my noggin’ is that there is no good/evolved resrvoir remaining under Herdubreid and Herdubreidartögl. So the new quake-set we are seeing between 15 – 8 km is in fact fracturing-quakes from a developing magma reservoir, or re-activation of the old one. Ie, they appear like tectonic (the fracturing of the rock) and magmatic (when the magma moves into the new fractures) at the same time and that duality makes them harder to distinctly classify.

    In my own scale of icelandic volcanos I would say that Herdubried and Herdubreidartögl has had it’s first beer on the six-pack scale (deep crustal magmatic quakes) and are well into their second (evolvement of magma reservoirs), but they are still 4 beers away from eruption. But there is nothing to say that those 4 beers might not be quick, remember that they popped the first one in 2005, and that we are talking about subfeatures of Askja and that one has enough power to blow through a six-pack in minutes… Ie, this might be a fissure eruption from Askja in the making, and then it will probably be major.

    1. I forgot this one…
      Prof. Hazel Rymer who has studied Askja since 85 has linked the inflation process that started in the Askja system in 07-08 to Herdubreidartögl. Remember that untill 2007 Askja was deflating after the 1961 eruption.

      News article:
      http://www.earthwatch.org/europe/newsroom/science/news-3-eruption.html

      Scientific article:
      Rymer, H., C. Locke, B. G. Ófeigsson, P. Einarsson, and E. Sturkell (2010). New mass increase beneath Askja volcano, Iceland – a precursor to renewed activity? Terra Nova, 22, 309-313. doi: 10.1111/j.1365-3121.2010.00948.x

    2. Unless it’s French in nature (God forbid) and gets sozzled on champagne in which case 2005 was shaking the bottle and 2009-to-present represents removal of the cage on the cork…

  11. Hm, well there was a world record in cheapest Christal-champagne in Reykjavik during 2008 so the volcanos might have swittched for economic reason to champagne in the aftermaths of the economic crisis.
    But one would think they would be drinking mjöd!

  12. Anyone noticed the earthquake near Laki that the IMO has just put up on their site? Sends a chill down my spine when I read an earthquake ”x km from Laki”

    1. It’s far to the west from Laki, even west of Eldgja. It’s almost at the river Tungnaá according to the maps.

Comments are closed.