Earthquake swarm starts on the Reykjanes Ridge

It appears that a earthquake swarm has started on the Reykjanes Ridge. This earthquake swarm appears to have started with a earthquake that is ML3.6 to ML4.0 in size or larger. But I don’t think it is a Mb5.0 in size. On the earthquake list on the Icelandic Met Office web site there are several ghost earthquakes. But I did just record one earthquake on my geophones.

The current area of activity on the Reykjanes Ridge. Copyright of this picture belongs to Icelandic Met Office.

This looks like a normal earthquake swarm on the Reykjanes Ridge. So far nothing suggests that this means a eruption is about to start in this area. But that might change without warning since this is a volcano area.

I am going to update this blog post if there are any more strong earthquakes on the Reykjanes Ridge.

86 Replies to “Earthquake swarm starts on the Reykjanes Ridge”

  1. Thanks Jon – Are there any large volcano in this region similar to Hekla or Katla in size?

      1. I guess you want to know if there are volcanoes in this area with a history of powerful eruptions like Hekla and Katla. No, they aren’t. These rift volcanoes like Jon said, are the kind of the fissure type, occasionally being of Surtsey type. So, between efusive to mildly explosive. And eruptions are not as often or as powerful as in the eastern or South of Iceland, where most famous volcanoes are.

  2. These show well on the BGS Helicorder plots, select Very long Period. No other earthquakes tally from USGS data.

  3. Sorry G1, confusing this refers to the helicorder plot sensitivity, short period looks only at the UK long period ‘looks’ world-wide. A

  4. Sorry for delay in reply, web link drops out – we’ve a massive storm on!!

  5. Not dark yet, just getting darker – There was (is ?) one webcam on Eldey Island ( website) but its off now (its shut off during night-time it says, but I think it has been off for some time, but not shure) but I do not know what direction it points to. It was set up for birdwatchers on this tiny island. Where I sit some movement can barely be felt (but I am shure its rather strong swarm and is on-going). Eruption? Maybe, maybe not, there are recorded instances (in middle ages) of eruption(s) in the area followed by Katla Volcano.

  6. “”Eruption? Maybe, maybe not, there are recorded instances (in middle ages) of eruption(s) in the area of “Trölladyngjur” followed (possibly) by Katla Volcano. It is not proven where this eruption was.”” Correct this way, about year(s) 1354, 1357, 1360 or even 1362 (ref: book by Werner Schutzbach: “Katla – Saga Kötluelda” Lafleur – Reykjavík 2005, ISBN 9979-9707-6-6 )

    1. I don’t think there is any connection between Reykjanes ridge and Katla. Eruptions might happen around the same time, but would be coincidences. Or rather, during a period of high volcanic activity in Iceland (hot spot periodic cycles of activity), there would be increased activity in both places.

  7. I guess what it is really interesting today (besides the Hamarinn flood) is the earthquakes off Katla caldera. Particularly as they form a line from Reynisfjall (the very south tip of Iceland), towards NNW to the point where Jon spoke about an interesting spot of recent increased earthquake activity, and continuing to the southern part of the caldera, where most earthquakes usually happen.

    One could speculate about some kind of fissure, but (big but) what really happened is that the earthquakes to the south, outside of the caldera, are deeper as they are further away from the caldera. I don’t know what this means.

    I don’t even know why this orientation is SSE to NNW and not the usual SW to NE. But Reynisfjall follows this orientation, it is a mountain ridge pointing to Katla.

    A little bit between Reynisfjall and the interesting spot of the earthquakes, there is also a lake in what it seems to be a old crater, but this is a little bit further east.

    1. Intersting quake also inside or very near in Bardarbunga Volcano at 19:53 hrs. Ml 1,7 – 69% quality.

  8. After this swarm we can expect a new “wave” of shaking all over the country, according to my amateurish observations. 🙂

  9. off-topic, there is a nice display of noctilucent clouds over Iceland, when with the sky quite cloudy
    and there might be strong northern lights forecasted for tomorrow, as a result of a major solar flare hitting our planet

    1. you can also see it in almost webcam 🙂
      the clouds glow a bright electric blue

  10. A new large earthquake did just happen. This one was close to my geophone, as I can estimate the distance from the P and S waves. I do not yet know how strong it was or where it is located.

    1. It was not that large after all. It was just a ML1.7 at Búrfellsstöð. But that is real close to my Heklubyggð geophone. That is why it did appear so big on my geophone.

      Sometimes I get fooled too.

  11. Let me think out loud.
    Once again I see a pattern repeated: Earthquakes at Central Mid-Atlantic Ridge, then swarm at the Azores, then swarm at Reykjanes… we might expect more swarms at Tjornes Fracture Zone and Kolbeinsey, I suppose. Up to Jan Mayen…
    Let us wait if this makes any sense at all…

  12. Thursday
    04.08.2011 10:35:35 64.011 -19.683 3.6 km 2.0 90.07 2.3 km NNW of Hekla

    1. Indeed.. I just wanted to post a comment about that one 😛
      Wonder how the quake looks like on Jons helicorder is it magmatic of origin?


      1. Correct me if I am wrong… but Hekla has no caldera… only a magma chamber deep down and small craters on the volcano itself… isn´t that correct?

  13. 2.0 just now almost in Hekla itself. can anyone post the link to Jon´s geophone once more?

    1. Yup! Others beat me to this alert.
      Iceland is certainly rocking this last 24hours.
      I really was too quiet last week!

      1. My husband will vouch that I wasn’t quiet last week!! IT(Iceland) was!

  14. 10:35:35 64.009 -19.682 4.8 km 2.1 99.0 2.0 km NNW of Hekla????
    Hey folks, it’s still sort of deep, but given the recent inflation and all the shaking from MAR, we could well expect a large 5.0, shallower, preceding an eruption.
    Eyes open!

  15. Calm down Renato!
    (Gets in a supply of popcorn and extra coffee for possible sleepless nights. Enough to share with fellow volcaneers. )

  16. The 2.1 earthquake 2.0 km NNW of Hekla seems like it could be interesting.
    I read before that that Hekla is generally aseismic apart from before an eruption.

    I’d like to hear Jon’s thoughts on it.

  17. A major flare (M9) has happened on the sun and start from tomorrow, massive coronal ejection materials will arrive on earth, which will have some effects.

    1. So far I haven’t found any evidence from our experts over the two blogs as for flares having any influence at all over volcanoes.

    2. This has no effect on the earth in terms of earthquakes and volcanism. The material is completely absorbed by the upper atmosphere, how should this reach the earth?

    3. ESA reports now via Twitter^^:

      @esascience ESA Science Team
      #Solarflare update: According to @NASAiSWA, today’s M9.3 CME likely to interact with yesterday’s. Combined effects to reach Earth Friday pm.

      good morning 😛

  18. Tremor at hekla still seems stable worth keeping an eye on for a bit though.

  19. I noticed there still are earthquakes occurring from time to time in a small area south of Mýrdalsjökull. That’s interesting. Is magma pushing there?

  20. @Renato, I think you’re a bit off the mark anticipating a M5 at Hekla; IIRC the last eruption started with nothing larger than a 2.6 preceding it.

    Yes it *could*. But it doesn’t have to 🙂


    1. Mike:
      Sorry, but this information has been repeated over and over from people here and over EB and I took it for granted.
      Should have made my own research.
      Thanks for pointing it out. 🙂

  21. Earthquake below Hekla this morning:
    Thursday 04.08.2011 11:27:57 63,549 -19,111 1,1 km 0,3 40,92 3,5 km S af Hábungu
    Its clearly visible on Jóns Helicorder.

      1. You are right, I got the wrong quake from the list. The right one is this here:
        Thursday 04.08.2011 10:35:35 64,009-19,682 4,8 km 2,1 9,0 2,0 km NNV af Heklu

  22. If anyone is interested I have a site of a webcam on Videy Island if you want to see it. It may be helpful it may not….perhaps a kind Icelander would better know how it is facing.

  23. The Heklubyggð helicorder show some constant, but very low, signal. Is this due to a measuring error or something significant?

    1. It’s something that happens on the current hour. You will notice it will get flattened out when it moves on to the next hour. 🙂

  24. I am no expert on this matter, but due to the location of these earthquakes at the south end of the Myrdalsjokull Glacier, it may perhaps be Ice simply crumbling away on the very edge of the Glacier, or is it too deep for that? Someone please correct me if I’m wrong!

  25. A week (or so) ago, we had a M2.6 (2.8?) 4 km ENE of Hekla at 20 km depth. Today’s quake is almost under the peak (2 km N) at 4.8 km depth. Two quakes this close to Hekla is more than I’ve seen over the 18 months I’ve been following the IMO report on a daily basis. Then again with Iceland so seismically active you’d expect quakes to have occurred just about everywhere over such a long period.

    Still, I feel Hekla bears watching.

  26. Just to remind us of Jon’s interesting spot on the edge of Myrdalsjokull SSE of Katla caldera. Here is his post last month

    I am still intrigued by the rhythmic, almost slow pulse like tremors at Alftagrof
    and at Lagu Hvolar
    It seems too regular for glacial activity or meltwater.
    Whilst we are waiting for action from the two Big ones, Hekla and Katla, maybe this is going to keep our interest and surprise us!

  27. The Hekla tremor is indeed interesting. As Henrik said Hekla has shown more seismicity in a short time now than during the past year and a half. And the quakes that does occur now seems to be within the range of where the magmachamber is supposed to be (5-8km deep).

    Regarding the quakes just south of Hábunga. I would not be surprised if that is a completely new intrusion of magma. Many of the quakes are quite shallow (< 1km) but some have been concentrated around 5km depth. Some kind of intrusion must be behind it.

    It will be interesting to watch how it all unfolds. And by that I mean both Hekla and Katla. They might decide to sing a duet in a not too far away future. 😉 Lets just hope it is a song of serenity rather than a symphony of destruction.

    1. It does look like that, or maybe or small earthquakes, thought nothing recent on the IMO page.

  28. And one more thin I read in a comment in one of the earlier posts. Someone asked why the volcanoes names are predominantely female. One poster had a very good comment about that.

    The reason volcanoes are defined as females are that they are stunningly beatiful to look at. They lure you in for a closer look but beneath it all they can be very dangerous and sometimes even breathes fire.

    😉 All in the name of a good joke of course.

    1. @LUIS:
      Trata-se de um twitter, não dê ouvidos a esse tipo de boatos que são muito perigosos!

      1. Renato é verdade… infelizmente! O BCE está a intervir mas não está a conseguir parar o pânico bolsista. Isto é de uma importância extrema e só por isso eu passei a informação. Não vou escrever mais sobre este assunto. Peço desculpa!

    2. Can we stay on topic? This is not the blog for Italian financial news.
      Earthquakes and volcano activty!. 🙂

    3. It was a tech problem, down 600 points last time i checked. Italy is already broken, no one can afford to fix it.

  29. Hello! Sometimes we do get off topic for a bit..and usually its pretty important. We share more than just volcanic news here as needed. THIS INFO ABOUT ITALY SEEMS IMPORTANT AND EFFECTS ALL OF US. WE mention aetna volcano here do we not? Sometimes people get excited…and i think we can over look a few comments in a different language once in awhile.

    1. The difference when people speak about Etna is that is a active volcano. If you want to discuss economics you can do so somewhere else on the internet.

      It is all good to speak about other volcanoes around the world here. But it is not going way off topic here as was done when the economic media drama crisis was mentioned here. This type of discussions do not belong on this blog. As I do not speak about the economic crisis here, I do that elsewhere (, mostly Icelandic).

      There are also plenty of other places that discuss this issue and the media drama surrounding it.

    2. One post in a different language is not going to kill any of us. But once someone else picks it up and it becomes a habit which would be a bad thing since this is an international blog. Plus, in support of Jon, yes Italy is important, but this remains a geology blog and discussing every single event in the world would not be appropriate.

  30. Yes this is a geology blog and i love like that! I will not post more posts about economic crash. Sorry for all the truble.

  31. Ok, now on the IMO map, there is three quakes lined up in a row. What is the story with that?

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