Posted on by Jón Frímann

Deep earthquake in Hofsjökull volcano

Among the most quiet volcanoes in Iceland is Hofsjökull volcano. It has not erupted in at least 12.000 years from it’s main crater (far as I know). But minor fissure eruptions have taken place in the last 12.000 years in the area around Hofsjökull volcano. But they are undated far as I know. Because of that it is now known when the last eruption took place in Hofsjökull volcano. In terms of Icelandic volcanoes, Hofsjökull volcano is more complex then most. South of it lies the Kerlingafjöll volcano. A volcano known for it’s heavy hydrothermal activity. But Kerlingafjöll volcano has not erupted in historical times in Iceland. But they might have erupted in the last 12.000 years without me knowing about it. In the case of Hofsjökull volcano looks are deceiving. According to a geological map that I have of Iceland, in the case of Hofsjökull volcano it has a second magma chamber and a central volcano inside the SW part of it. That volcano is unnamed for oblivious reasons. That volcano might well behave differently then Hofsjökull volcano it self. But I would theorise that this intergrated central volcano inside Hofsjökull volcano is going to be active when Hofsjökull volcano is.

The icecap in Hofsjökull volcano is deep. At it’s deepest point it is 650 meters deep at the most. The deepest points of the icecap are in the main caldera of Hofsjökull volcano. If Chaitén volcano in Chile has teaches geologist anything. It is that a long dormant volcanoes don’t need a long time to go from dormant to active eruption. That is why I find it worrying that deep earthquakes have started to appear in Hofsjökull volcano, even if they are extremely rare so far.

Over the past ten years or so there has been a slight increase in earthquake activity in Hofsjökull volcano along with increase in hydrothermal activity. But so far it has just been a minor earthquakes. The strongest ones getting up to ML3.0 at the strongest. No earthquake swarm have ever been recorded in Hofsjökull volcano to my knowledge (since recording begin in Iceland).. Last earthquake swarm was recorded in Hofsjökull volcano in the year 1999, then a earthquake swarm of 22 earthquakes took place, all of those earthquakes where just minor earthquakes. Besides being one of Iceland largest volcanoes, its location also makes it extremely dangerous. As it is located in the middle of Iceland, and a glacier flood from it could go many different ways down to the ocean and over large populated areas in Iceland. The increase in hydrothermal activity started in Hofsjökull volcano in the year 1994 or about that time. It was at least first documented in that year. A sulphur smell was recorded when the homoeothermal vent was checked out that year in Hofsjökull volcano. Increase in hydrothermal activity in Hofsjökull volcano is interesting as it is followed by a slight increase in earthquake activity over a long period of time.


Location of the two earthquakes. The deep earthquake is the one closer to the caldera. This picture is from Icelandic Met Office web site. The copyright of this picture belongs to them.

The earthquake that started me to get worrying about Hofsjökull volcano is the earthquake that took place 10:11 UTC on 5. April 2011. That earthquake had the depth of 27.6 km. It’s size was ML1.4, so it was a small earthquake. I do not believe that this depth is a result of a error in the SIL system (can happen sometimes). A second earthquake took place at 10:13 UTC, its size was ML1.6 with the depth of 1.6 km.

Whatever that is happening in Hofsjökull volcano is worth watching. Even if it not going to erupt just yet. It is also my opinion that Hofsjökull volcano is not part of Western Iceland Rift Zone (pdf). But its is the most southern part of a failed rift zone often called Skagafjörður volcanic zone (pdf). It is a failed volcanic zone that is mostly extinct, only Hofsjökull volcano and Kerlingarfjöll volcano remain active in that volcanic zone at the most southern end of it.

Other information.

Jarðhiti í Hofsjökli (Tímarit.is, Icelandic, 1996, pdf) – Article with picture of where the hydrothermal vent was found in Hofsjökull glacier.
Hofsjökull (Wiki, english)

Text updated at 18:11 UTC on 6. April 2011. Minor fixes in the text.

68 Replies to “Deep earthquake in Hofsjökull volcano”

  1. As if there were not enough volcanoes to worry about, now we have Hofsjökull volcano!
    How interesting!
    Thanks for the post, Jón.

    1. So far there is nothing to worry about. But this development is interesting. But nothing indicates that a eruption cycle is about to start in Hofsjökull volcano.

  2. I find this quite interesting. Very nice post.

    I also think that the Skagafjörður rift axis fits in the grand scheme of things, since the rift jumping and the “vague western boundary” of the Trögllaskagi microplate didn’t seem symmetrical with the more well known ancient cuts of the mid Atlantic ridge. This feature fills that apparent symmetry gap.

    It also clicks with something that happened back on 26 October 2010. An oddball quake swarm ot in the middle of nowhere. The center of that swarm was ≈50 km northwest of Hofsjökull under a lake. At the time, my question was how a lake can have a causal effect in making quakes happen up to 20 km deep.

    As it turns out, this lake, and the swarm, both sit along the axis of the Skagafjörður rift. According to the SIL data that I have on hand, that swarm lasted at least until the end of the year. Not a big swarm… just a collection of quakes that seem to fall into a common area.

    Jón Frímann and others who are more well versed in this topology than I am can elaborate, but I think that this ancient rift may have shifted or moved… or has felt a different stress load, and that has led (or is related to) to the odd bit of activity at Hofsjökull. Most likely with the volcano doing what volcanoes do (move magma around) and the rift doing what rifts do (creak).

    That’s my 2 cents… I am not a geophysicist, seismologist, nor am I an expert. I just plot stuff.

    (I plotted this swarm a while back and linked it on this blog, I’ll repost it if requested, but it doesn’t really apply to this volcano)

  3. Interesting post! Thanks!
    Could this rift zone with it’s ancient faults have caused the Blondulon earthquakes last year?

    1. I think Blondulon is the lake Lurking is talkin about when he mentioned the odd event (earthquakes) on the 26th of october 2010.
      Henk

  4. It is a question if there is a SISZ like fault zone between the Eastern Icelandic Rift Zone and the Skagafjörður Volcanic Zone (or what is left of it). But such fault zone is not on any of my maps.

      1. I think that everyone else account is save. It was most likely a targeted editing on that post.

        I am not sure how it was done. But my password was not changed far as I can tell. But I did change it for security reasons.

      2. Which version of wordpress are you using? If its below 3.11 I would recommend to update it. The latest update fixes a lot of security issues.

      3. I am using version 3.1.1. I always use the most recent version of WordPress to prevent security issues.

        But I am sure that the post did not switch to private mode and half of it did not vanish on it’s own.

      6. No, thats fine. First of all I am not very sensitive in this and I would let you know. Don’t worry.
        I was just thinkinh, would could possibly be the problem. And sometimes (I know this very well from myself) you oversse the most obvious reason.

    1. There is a strong wind in that area at the moment. So it is having a effect on the tremor plot. But besides the wind the odd status of it continues since it did start on 25. March 2011.

  9. If anyone is lives near it and would like a walk, Jon said a few post’s before, “Its need’s a good kick that is all” (:

    I would, if i could, but i can’t.

    BTW Jon, I saw you on a few online news sites over the past week or so.

  10. Sure,

    “Iceland: Volcanic activity has been pretty quiet in Iceland lately. That hasn’t stopped Jón Frímann from being busy – he recently posted what could only be called the “Cliff Notes” for Icelandic eruption. Check it out to see how active the island has been over the ~1,200 years”.

    http://bigthink.com/ideas/37694

    Other sites are well.. Strange, like survial blog and end of the earth stuff, Maybe you all have seen them around before, Just a personal opinion, but i like common sense and fact, hard work and learning, all available on this site.

    There was another news site, i willget that like asap.

  11. I just saw this now. Katla based at 0.1KM, Could it be a icequake?

    Thursday 07.04.2011 13:24:11 63.635 -19.190 0.1 km 2.0 99.0 3.0 km E of Goðabunga

    1. No. I don’t think it was a ice quake. The quality it did register on the automatic SIL system was too high for this earthquake to be a ice-quake.

  12. Fits right in there with all the other earthquakes that have been happening all over the world…………little ones, in numerous strange places, some of which haven’t had, or rarely had earthquakes. Check Google Earth…………zoom in fairly close and check all the places all over the World that have had small quakes. Solar flares heating up the magma? One plate moves, they all move. No one is paying attention to this, and I’m a freak, or so they think, but I’ve been all around Google Earth and there are tons of earthquakes, on fault lines and in areas where none or hardly none existed before. I’m in Canada, and we’ve had one here also…………..after how many years? They all started about a week before the Japan quake and are continuing. The sun is in it’s 11 year active period and sending out lots of flares and geomagnetic storms, the latest being a couple of days ago, and should come toward us tomorrow, I think. I have to believe this is a contributing factor……………..and I’m watching Yellowstone, which has had many and is a super-volcano. Very interesting stuff. 🙂

    1. The answer to that would be no. The earthquakes happen at random. But at plate boundaries or in other locations where they can take place.

      There is no sun connection and never has been. The Earth crust is full of old fault lines as the plates have moved over the billions of years. Any of those fault lines can become active if the right conditions are in place. It however almost never happens in some areas, while other areas are more active when it comes to old fault lines.

    2. The current mainstream body of geological science does not subscribe to mutual tectonic correlation, or global tectonic instability. However, what is happening underneath the crust is another matter and open to speculation. As with any science, it takes a series of anomalies that challenge the current paradigms and the methods constrained by them before a scientific revolution can occur to try to explain the anomalies. Are we having anomalies? I think so and I think they will continue. I personally feel its beyond anyone to even slightly understand. But only after a long period if they continue will they strain the current paradigms if at all. My take, although very lay.

    1. Is that was has caused the spike reading in all the 0.5-1hz graphs on the Icelandic monitors?

    1. Hekla is constipated in my view, but when it decides to finallly let loose, the goo behind the poo will surely spew.

      I am not a scientist. I am only a nut.

    2. Wow that looks strange, in the last weeks there sometimes was a opposing movement between red and blue lines. But it happened quite a lot now :O and quite some strength peaks to 15 and 20

      Sander

      2. No, the low-frequency spikes you see, are probably caused by the M7.1 earthquake in Japan.

  16. I’m really curious what these strain anomalies near Hekla mean. Does anyone have a clue how to interpret them?

  17. For more than 24 h with these anomalies in Hekla strain, there was so much wind?

      1. ok, like yesterday at this time of hekla tremors were quiet, not weather related, have any explanation for the behavior of the tremors in VAT in the frequency of 2-4 Hz, it seems like there’s a constant noise.
        http://hraun.vedur.is/ja/oroi/vat.gif
        translated by Google

  18. Hekla has been showing plenty anomalies lately (strain-meters, some nearby quakes, dry streams). I think she is as ready to blow, as is Grimsvotn.

    Tremor in Grimsvotn continues increased.

  19. Good morning Jón,

    At 05:11:10 hrs there was a MW 1.0 at 19,2 km deep near Katla (Godabunga area as you told me a few days ago).
    Does this mean anything when you look at the depth?

    Kind regards,

    Henk

    1. The reviewed location did show that was on 0.1 km depth. The automatic SIL location was poor (32,49). When it is that low, the location is wildly inaccurate and unreliable.

  20. Do other volcanos around the world show similar low-level (Mw < 4) type activity as magma moves around? There was a 3.4 just south-east of Mount Rainier earlier (about 14km south-east) which if was seen at Katla for example would probably raise some eyebrows!

  21. Paypal has limited my account just because they feel like it. I am going to try to withdraw the donations that I got there. But if that does not work out. I am going to refund everyone back.

    I will keep you posted on this issue.

    The paypal buttons have been removed and I am going to close down the paypal account when this is over.

  22. Jón, that means you can’t receive the donations?
    What are you saying, man!
    Check this, but please, don’t talk about refunds.
    Whatever reasons they might have, they are the ones who should have told us in advance, and give back the money they don’t own.

    1. Jón, is it possible that someone might have hacked your paypal account in order to collect the donations that were meant for you?

      1. If you need, I have copies of all transactions made with paypal and I can e-mail them to you

      3. No. I use different password for paypal then on this blog. It is also connected to my icelandic credit card and is locked into it.

        So that did not happen.

    2. Yes, that means I cant move the donations to my credit card. But I am going to try getting them there. But the history might not be good in that matter. In the worst case I am going to refund people.

      But I am still waiting for a answer from paypal. But that might take a long time.

      I have contacted the EU, as this is illegal in the EU without a reason in my opinion.

      1. Are you sure that you are looking at a genuine copy of Paypal and have not been dierected to a fake scam site by a phishing email?

      2. I always hand type on the address of the paypal web site. So no, this is the real paypal.

        Besides last month and this month there has not been a lot of activity on my paypal account. After this is over, there won’t be any activity on my paypal account. Because it won’t exist at all.

      3. Also, you can telephone Paypal and talk to them immediately. They are quite easy to talk to.

        For Paypal in the UK we ring 00 353 1 436 9004. If that is not the correct number for your Icelandic account, they will give you the right number.

  23. I’ve heard that paypal are very alert to unusual patterns of payments, in order to combat fraud. It may be that the donations coming in in clusters has caused an automatic shutdown, and you will need to prove to them in more detail that you are who you say you are. It seems they are strict, and sometimes they see patterns that aren’t there. Banks do the same – I know someone whose bank refused them a purchase because spending a thousand pounds on a laptop didn’t “fit their normal pattern” and so the computer assumed the card was stolen. Contact them and find out, but it is probably something annoying like that…

    1. You never tried to deal wit paypal yourself, right? This is a nice system for paying, but not for receiving money. If you try to contact service, you mostly get some standard messages back.

  25. Had a dream last night that a very large quake had hit Mexico and it was thrown into turmoil. Now I can’t shake off the feeling. Weird.

  27. There were quite a few earthquakes recorded in the close vicinity of Grimsfjall and also the tremor plot has changed. I’m no expert at all, but in my opinion there’s really something going on. I can’t imagine that it’s related to bad weather or ice beginning to melt.

  28. The Hamarinn is the lesser of the 3 stooges, but the producers promised it would get some lines in the new movie. The questions is: what is coming next for the other 2 stooges and when.

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