New dike intrusion into Katla volcano caldera

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A new dike intrusion has started in Katla volcano caldera. So far only few earthquakes have taken place. But the largest one so far is ML2.8 in size with the depth of 0.8 km (800 meters). It appears clearly on my geophone at Hekla volcano. But it seems that new area in the Katla volcano caldera has been increasing activity during past few weeks. Based on the number of earthquakes that are currently taking place there.


The earthquake as I did record it on my Heklubyggð geophone. This are all the directions on the gephone. This picture is released under Creative Commons licence.


The North-South component of the geophone shows the nature of this earthquake clearly. This picture is released under Creative Commons licence.


The vertical component of the geophone did also show the nature of this earthquake clearly. This picture is released under Creative Commons licence.


The area inside Katla volcano caldera that is responsible for the current earthquake activity. Copyright of this picture belongs to Iceland Met Office.

The earthquakes in Katla volcano now are created by magma intrusion into the rock layers. There is not a lot of about tectonic earthquakes in Katla volcano today. But they cannot be completely ruled out. But the signature of those earthquakes is different then by earthquakes created by magma movements.

Note: I have been recording earthquakes since the year 2006. I have learned a lot during that time.

This entry was posted in Dyke intrusions, Earthquakes, Iceland, Katla / Mýrdalsjökull, Magma, Monitoring, Swarm, Volcano. Bookmark the permalink.

841 Responses to New dike intrusion into Katla volcano caldera

  1. renee says:

    People come here to learn and get quality information, many of us. If this blog does not appeal to you in the manner it is please create your own or find another. Please do not make life difficult for Jon. We are here because we like it here if you do not then please find a place where you will be happy, you do not need to change us to fit you.

  2. renee says:

    You probably hate sheep too!

  3. I have a solution. But it takes me about two days to fully implement it. I had it originally planned for next month (I had seen this coming for some time now). But this should be a permanent fix to this issue. But this is also a expansion to the blog and the community around it.

    It might result in fewer blog comments here. But that is good with me if the quality of the comments are better. But this takes a little time to implement, so take it easy while I am working on it. But please keep the off-topic to a minimal while I am setting this up.

    • inannamoon says:

      A couple of suggestions to take away with you to consider while you work on the expansion to the blog. As Carl suggested, a cafe bar (cocktail party?) thread or if possible, a chat box.

      Any other ideas/preferences from the readers or, Jon, any hints as to what changes we are to expect? :)

  4. Xana says:

    The tremor spikes on El Hierro – due to explosions apparently – have been up to 15 herz. I found this series of videos on Youtube that clearly show what the effect is on material by prolonged exposure. Sure El Hierro is not made of walnuts and marbles, but I hope someone here can tell what happens under and on the island when this frequency affects soil, magma etc.
    http://www.youtube.com/watch?v=4HjXSfikD4w

    The spikes I mean are like those in the picture. They last perhaps a minute or two, but the effect must be pretty big I conjecture: http://www.ign.es/ign/head/volcaSenalesDiasAnterioresHora.do?nombreFichero=CHIE_2011-11-13_11-12&estacion=CHIE&Anio=2011&Mes=11&Dia=13&tipo=2&hora=11-12

    • Another Peter says:

      There is nothing special about 15 Hertz vibrations. The movie showed the marble rising in the walnut shell, even though it is denser; that is due to the vibration moving it around an allowing some shell to get underneath, and would happen with quite a wide range of other frequencies too.

      As to the tremor spikes, what the red colouration up to 15 Hz shows, is that *ALL* freqencies up to 15 Hz got louder/stronger. Down around 1 Hz in the spike, the colour is brown, showing that that too is louder that shown by red between spikes.

  5. richard jenkins says:

    found you from the wikipedia Katla page!
    when she gonna blow!

    • M. Randolph Kruger says:

      http://rsta.royalsocietypublishing.org/content/364/1845/2073.full

      This is a good article that tells us the diff between types and sizes of eruptions and the power that they generate.

      Light reading Judith. Bottom line is that if this continues and it finds a way into the islands internal system without releasing, its likely to go off like a bomb.

      Most of the time a volcano builds a dome and goes to sleep. Indeed that might have happened here in El Golfo after it built El Hierro. Erosion obviously took place because you can see the perimeter of several large rims, and look at the edges of the rock falls. Very interesting in that they are shear like you would expect from a dome failure.

      And with most of them the new activity starts with the rims and on the edges of the old dome inside. Did that happen here?

      The edge of the old dome is the beach area of El Golfo. Not much of a beach but a lot of indication that it is the old dome, just eroded by the ocean. Its also where the rock slides have been occurring. Is it breaking rock and causing the falls? Is it tremoring and causing weak points to fall? Or is it invading tubes below the mountain and looking for a way out? Not sure on any front.

      Making a lot of noise though.

      Either way I think we are heading towards a multi-year eruption with this and with all of the usual racket generated by a volcano being born. This one is a bit different in that at some point there is going to be a huge landslide IMO. Big enough to generate a tsunami is the question. It might go and then be stopped by the new dome formation… One could only hope.

      If you have been following Lurks plots, there seems to to be two distinct chambers. The one to the SE I think its being fed from the lowest one to the SW, moving laterally into weaker territory around Resting -Bob Maximus, with the main show really going to be in El Golfo-Bob Minimus later on this year or early in the next. It simply has a lot of capacity and its not terribly full of material but its getting that way fast. Really what are we seeing at Restinga? Raise that chamber there up 1 mile and you have a new island. Its almost the width of the SE wing of Hierro now. About the same diameter, vertical size. Then the deeper west wing raised to the surface is about the size of El Golfo as it once was thousands of years ago. So, I am betting that we might get a huge show out of this one.

      All in all we might be astounded later on by what starts to happen.

  6. Dagur Bragason says:

    Here is video from last summer that shows Mýrdalsjökul and surrounding areas in details:
    http://www.youtube.com/watch?v=MzxiTtN9FTM&feature=related

  7. M. Randolph Kruger says:

    INSTITUTO VOLCANOLÓGICO DE CANARIAS

    Durante el vuelo del día de hoy, los miembros de INVOLCAN así como los de la unidad de helicópteros de la Guardia Civil de la zona de Canarias, fueron soprendidos por una deslizamiento de tierras y rocas en la zona norte de la isla. Afortunadamente sucedió en una zona despoblada y la instantánea pudo ser capturada, aquí os la mostramos

    Volcanologists INSTITUTE OF CANARIES

    During the daily flight members of government and the helicopter unit of the Guardia Civil in the area of the Canary Islands were amazed by a landslide and falling rocks in the north of the island. Fortunately it happened in an unpopulated area and could be captured instantly.

  8. I will make a couple of comments on this.
    Jón, it is a fact that people tend to not state if they are happy with things, only if they are unhappy. I think you are making changes depending on the voice of a few people who have complained, the wast majority is though quite happy as it is.

    Erik tried to make more money per blog-post, and moved his site twice into spaces that was increasingly user unfriendly. In the end he now has a pittance of the crowd he used to have. Why? Because he forgot that the single most important thing a blog has is its followers. You have in short time passed Eruptions in amount of hits, and the reason for this is that it is easy to comment, and that people feel at home. Period.

    I would seriously rethink doing drastic changes that limit things. And if you really feel the need, you should listen to the crowd very well. Because as it is now I think that quite a few would walk away. Remember that many are walkaways from other sites where they did not feel wanted, or the reason of the site changed to much like Eriks.

    Currently I do not feel that wanted, and if I am not wanted I walk.
    I will think about things for a day or 2. I will come up with something, that is what I do. Because one thing I have noticed, that is that I “need” my living-room scientific bantering room. And after following scientific blogs in various subjects since the inception of the internet forums and blogs I think I know how it should be done. And with almost limitless resources at hand I can solve a problem if I need to.

    Because in the end it boils down to this, if I wish to have fun I will not allow anyone to stop me. That is not who I am. And if I wish a fun place, well, I will have one.

    • Josh says:

      Completely agree. But then, I do not have to spend any time deleting hundreds of spams…

      • Something that about 10 people have said they could help out with. Because this place will sooner or later need a helping hand.
        My vote would be for Diana as a help moderator.

        I think the biggest problem right now is that Jón does not really want help. And that things is starting to become a bit much together with everything else he needs to do.

    • Sissel says:

      I agree 100% with you.

      • Sissel says:

        This was of course at Carl!

      • oldcowboy says:

        I agree with Carl – this blog is both fun and interesting the way it is, and need all the different “caracters” in it. From time to time there might be a bit too much “off-topics” – but does it really matter that much?, as far as I can tell it’s polite and fun… – and when there are serious stuff going on (Hierro or Iceland) off-topics are gone immediately.

      • Ursula says:

        Yes, I also agree and I the comments are self-regulating: when something happens, everyone stays on topic.

        And as I already mentioned, I’m the one of walkaways from Erik’s blog, so this does actually happen when the place changes.

    • renee says:

      Well said!

    • Denise says:

      I also agree with Carl here. I think that this blog is the perfect mix of good scientific information, discussion and speculation with interesting and often informative fun chatter. In addition to the seismic and volcanic discussions, I have learned a lot of interesting things from the high level off topic commentary. I hope that you don’t change anything, Jón.

  9. Ken.P says:

    I think Carl is right, and that major changes might destroy the happy character of this place.
    I’m not a scientist, but with increasing health problems I might have to give up sailing and find something less physical to do. I think I might have found it here.
    Had it been a strictly scientific blog with no chat, I probably wouldn’t have felt welcome enough to stay.
    You’ve done a fine job Jon, I hope it continues.

  10. While it is quiet in volcanoes and earthquakes (as so often happens when working on limited area of the planet Earth). I find it important that off-topic discussions is in a place that fits it.

    This might bring fewer comments here. But they are going to be easier to track and read up on. A large section of comments that has nothing to do with subject at hand confuse the reader and annoy him. Bad experience make it less likely for people to come back to this blog and I find that bad (that is the way human nature works).

    • Jón, you are going at it the wrong way I think.
      You have in short order become the owner of one of the largest scientific communities in the world. Full stop. That is something you should rightfully be very proud of achieving.
      My point is that something must be, and is, different here than at other scientific blogs. It is important to think about why? I am a firm believer that your mega-click status is out of the friendly open, and sometimes whimsical, nature of this place.
      If you change it to much I am afraid that you will shoot yourself in the foot. Because, all of the coments are actually a large part of the mega-hits.
      If I have calculated it correctly (and I know I have, I live on calculating things after all) you are currently worth 10K$ per month in advertising. Only problem there is to actually haul in the cash. (calculation based on every hit being worth 1 cent, which is industrial standard).
      There are probably quite a few companies that would be interested in being visible in here.
      Any changes therefore should be made in such a way that you do not loose the majority vote, and that is for the open, friendly and occasionally whimsical, nature of this blog. I am absolutly certain that you would loose more than you gain by restricting things.
      Think about things, and be open to the opinion of the longtimers. We are here because we like it after all, and have been here for a long time.

      And on another matter, please accept a bit of help on spam-moderation. You are not a man alone, you will need the help as this site becomes even more successfull.

      • Alyson says:

        There is a lot of pressure in volcanoes, and prediction is difficult. On here people look out for new information that will add to or disprove another comment. Sometimes I say stupid things, and people quickly point that out, and sometimes I focus on something that is relevant and points discussion in a way that develops usefully.

        Iceland, the Azorres and the Canary Islands have the potential to impact on all of us, and we very much appreciate the opportunity to share knowledge and ideas in ways that are and can potentially be useful and even life-saving. I am desisting from scare-mongering even while I worry that risk is being minimised on El Hierro. The example of Iceland with its networks of measuring instruments and the Iceland Met Office is superb.

        I learn so much from this mix of people with so many different perspectives. I have read so many papers and weighed Lurking’s wonderful plots against the different theoretical models. The community of posters here is getting to be much larger than it was, and I am sorry if we sometimes cause you to be stressed by things we say.

        Thank you, Jon, and thank you everyone who contributes to this shared learning environment.

  11. Una Canaria says:

    @Jon Friman

    I want apologize for causing troubles between the users of your blog. I understand the reason because I read it before, so I decide writing this note.
    I know perfectly that you designed this blog to discuss about volcanology, and it´s visited for a lot of people all over the world, and this is magnific. It is fun, I learned a lot, and I tried to help as possible ( a little bit) with “Bob”.
    On the other hand, I´ve also tried to be kind with everyone and even I improved my poor English in order to communicate better. I think that I´m a sociable and educated person, and when someone engage a conversation with me I behave that way.
    I understand that your blog is not the place for that. That´s my fault.
    But, on the other hand, and before to go, I want to make clear one thing. Someone ( I don´t know who) wrote the words “chat” and “party”. It´s really offensive for me. That´s idea in not in my mind, but perhaps in himsefl/herself it is.
    And that´s all. Thanks very much to let me share with you your knowledge and congratulations for the blog and the incredible work that you are doing, Jon. Regards for all and good luck…and many..sheps?

    Judith

    • You have not been any problem Judith. Your input is welcomed, in any language. This blog also has to cross the Icelandic to English limitation. That is often complex and time consuming during the nature of Icelandic language.

      Now I have added Spanish, a language that I do not yet speak. So things got a little bit more interesting and more complex, as the reader base did grow in accordance to what I did add to this blog.

    • Mafl says:

      Sheeps :)
      I’m happy to have you here. And if the vulcanoes of El Hierro go to sleep again, you could learn many things about Iceland and the vulcanoes up there!
      Hope you will stay here in this nice place…

      • Inge B. says:

        @Una Canaria.
        I think the same as Mafl. I would regret it a lot, if you wouldn’t participate any more.

        Esp. it’s very interesting to have so. who knows the Canary Islands so well. And on the other hand – as Mafl said – it could perhaps be interesting for you to learn about Icelandic volcanoes and their habits and compare it to the ones in the Canary Islands.
        :)

      • Newby says:

        Una Canaria, please, please don’t go!! It is so interesting to hear the things you have to say, most espcially because of you closeness to the action in El Hierro. Really there is no need for anyone to go. I have very little knowlegde of volcanology but am here to learn and I know I also have been guily of off topic remarks and if I had known they were so irritating to some would have perhaps put a stronger curb on my tongue. We have all done it at times I know. So please do stay. :)

    • inannamoon says:

      Hi Judith,

      I have that awful feeling in the pit of my stomach that you are referring to my earlier post: “A couple of suggestions to take away with you to consider while you work on the expansion to the blog. As Carl suggested, a cafe bar (cocktail party?) thread or if possible, a chat box.”

      Well, if it was my post, apologies as it was not my intention to cause offense. A “chat box” is what I call the little box that sits to one side of the web page allowing you to communicate with other people but not directly in putting into the actual blog comments thread – allowing the best of both worlds. You can see an example of how this works on Erik Klemetti’s page:

      http://www.wired.com/wiredscience/2011/11/hydrovolcanism-when-magma-and-water-mix/

      You can blame Carl for the cocktail party reference, at the mention of a cafe bar thread I had an image of us all sat around a hot cup of Joe deep in conversation. The evening version of that then popped up but we were no longer at the cafe but at a cocktail bar, sipping Gin&Tonics, White Russians and Mint Julep’s. :)

      Judith, I love all the comments on this blog and would prefer it not to change, but if change is to happen I think its best to try and influence it as positively as possible so we can keep what makes this blog great, comments from everyone including you – keep asking questions and posting ideas!! :)

      • Alan C says:

        Judith
        Please remember many posters here do not have english as their first language so comments posted may ‘come-out-not-as-intended’ no offence is meant so please stay with us
        Alan

    • Sissel says:

      Hello Una Canaria,

      It was always very special to read your comments, thank you so much for writing them here!

    • Diana Barnes says:

      You are no problem to me. :) Your English is excellent and you are a very friendly and intelligent lady :) More importantly… you like sheep:)

  12. Pyrotech says:

    May i suggest that perhaps Jon or a nominaed moderator warns people for going off subject. i am not on about people who bring controvercial comments if they are related to the subject, as the information for and against is important in free speech, and also people can have open debate, but probably more so about subjects totally off what discussion is about. Reading about someone’s next door neighbours dog for instance can be boring except for the two having the discussion. A private messaging ability or able to email each other may be an option that would limit some of this.
    Good luck thou Jon, excellent blog and some very good input from a number of users.

  13. KK4 says:

    I have been following this blog since its conception and birth. I have never posted before because a.) I never have anything worthwhile to say. b.)By the time I catch up on posts I don’t have time.

    This is the first time I have felt I have something worthwhile to say.
    I love this forum and it feels like home. It is an incredible seat of learning, please don’t underestimate this Jon and make changes. I introduced this forum to my, then, 13 year old son during the Eyja eruption, he in turn introduced his geography teacher to it. It has since become a great reference tool in the classroom (especially during Gimsvotn and now El Hierro.)
    The warmth, the banter and the approachability of the posters make this blog a very special place, the type of place that is lacking in the science world. The banter makes this place accessible to all. No matter what the level of intelligence, knowledge or age. It breaks down barriers

    My granny always used to say: “The child that shouts the loudest, is the child that gets heard. Even if that child is wrong!” I think that is the case here.
    I would like to take this opportunity to repeat Renee. ” We are here because we like it here if you do not then please find a place where you will be happy, you do not need to change us to fit you.”

  14. New blog post is up about all this! :)

  15. rosemary says:

    Hi all
    I am one of the many lurkers (I suspect) on this wonderful blog who are trying to understand what is happening on Hierro but probably have very little, if anything, of scientific value to contribute. Could I take this opportunity of saying that this blog is compelling to me and others like me, in part I suspect because of its unique mix of science and humanity with science being the undoubted bedrock (no pun intended!) of the comments. It is this combination of dense science and occasional glimpses of the lives of the posters themselves that fascinates and enlightens and delights us mere observers. I feel as if I am learning something, and I feel very priveleged to simply be alowed to lurk onboard.
    The fact that I do have a ulterior motive as I live on Tenerife and Hierro is approx. 60 miles from us according to Giggle, is all I have to offer as my excuse for intruding on what I regard as a very serious blog which in no way do I feel has become flippant. I am buying a book on Volcanoes for my 12 year old grandson, and it is thanks to you for the inspiration.
    But, Mr Kruger, just how concerned should I be if Iron Bob does really blow? Are we talking cataclysmic?

    • Hey Rosemary!
      I will answer that one for you.
      El Hierro is of a predominantly friendly type that produces lava flows and lava-fountains. That type is normally only dangerous if you get to close to them. And many of them are even possible to walk just a couple of hundred meters into. If you wish to see what I am talking about, go to Youtube and look for a video of the Fimmvörduhals eruption. There is video of a guy golfing into the lava fountain even.
      That type of eruption would probably even make tourism go up.

      Currently we are seeing an underwater eruption, at worst it will be a bit messy, but not dangerous if Bob continues and surfaces.

      An explosive eruption happening onland is rather unlikely, and if it happens it will be just for the few first hours because it is caused of groundwater mixing with the hot magma. It would be some ash, and nobody should get close to the eruption. But, cataclysmic, not a chance. A big nuisance but not more.

      If I would put it into percentages it would look like that.
      Bob continues, surfaces and keap on being the Bob we love for a while. 50%
      A new Bob surfaces out in El Golfo 35%
      Onland eruption like Fimmvörduhals 14%
      Small explosive onland eruption 1%
      Cataclysmic event 0,00000001%

      There is just nothing pointing to anything really dangerous happening. But, remember that people can still die from even the most mild-mannered eruption. If anyone on El Hierro feels heavy quakeing and sees a crack in the ground start to open… Run like Hell!

    • M. Randolph Kruger says:

      I point out that we keep thinking of this thing as just a volcano. We can handle the volcano. But you have to think macro rather than micro. Take the threats.

      They are: Ash fall, quakes that could rent the island apart, dome builds and then collapses and allows water to rush in, flank failure, flank fault failure, and of course with collapse, failure of any kind you get the possibility of tsunami.

      Bob Minimus for me is the danger point. Those poor bastards over in Valverde/Frontera dont know what may happen and frankly I dont think the IGN has quite got a handle on it themselves. I certainly dont. But, if those quakes started surging, magma invaded the internals in the island you would have to have kamikaze helicopter pilots to rescue everyone just to get them to transports to leave.

      Hey, how about that nice tunnel they built for it to come up through? Its nothing but a man made lava tube. It gets inside and its going to shoot out the ends like a rocket.

      Understand-The winds at altitude are from the west to east and southwest to northeast. The low level ash stuff would bury most of these towns just from the rollout onto the ground from some of the ash not being able to rise with the rest of it. Lately that is to the east lower level below 10,000.

      But are you okay on Tenerife? Very likely except if there is a failure of a wall or rift I would think. You wouldnt have but about 8-10 mins to respond if there was as a tsunami would roll over the island the beaches in about that time as it cranks out at 500 mph give or take a Banda Aceh or two. Height in that would be a major factor.

      But..Lets go a bit further. Lets say that either Bob Mimimus or Maximus go boom, or the island. The effects on the climate wouldnt be in question… Just the amount of damage to the food supplies. It shouldnt escape a soul that when Eyjaf went, the US center section got floods and couldnt plant. Then it got hot and everything planted died in the ground. Same with the Ruskies. Those guys are smart and pulled back on their wheat deliveries to the world food basket. By my count that cost something like 3.3 million dead in and around the Sudan. Couldnt buy food wheat and rice because for the first time in a long time… It wasnt available.

      El Hierro is a land mine, an old one with a temper. It has over 1000 volcanic vents on it and that by definition makes it a dangerous neighbor. Unpredictable and definitely not something that I would live on. Hell you can bet I would love to travel there (a year ago) but not sitting on top of the land mine watching someone beat on it.

      Safe? Safe is located in Cheyenne Mountain.

  16. Granyia says:

    This is the R. Margalef’s route today and yesterday – is that what it looks like when a ship is doing sonar mapping? If yes, we will soon see new pictures of Bob and the seaground.
    http://i41.tinypic.com/11ju1cz.jpg
    The Punta Salinas has been doing similar lines on a few days last week parallel the east coast of El Hierro, They might be mapping there as well.

    OT
    Oh, and Jon,
    thank you for this wonderful blog! I agree with KK4, Carl, Ursula, Lurking, Diana, Renee and all the sheepshleepers- a little bit of banter has never hurt anyone. Maybe marking OT comments with those two capital letters would help skipping them when reading through? I would be sad to see the blog changed.

  17. Betty says:

    I would love to read it, but I get this: “Error establishing a database connection.” I get this for the “older comments” link at the side, as well as the new article link at the top.

    What the hey, I only went to sleep for awhile! I was enjoying this blog so much. It was like reading an exciting book. This was the only blog I ever read where people actually say good night to one another. The thing of it is, when the volcano is just perculating, the down bits are filled in with interesting stuff, and when it’s busy, the analysis is great. It was all smooth, easy, and relaxing.

    Thanks a lot, whoever complained.

    • Are you getting this error on my blog or somewhere else ? If this is a error on my blog I need to know about it. So I can fix it.

      • Mirri says:

        i got the same message about 15 min ago, but i refreshed the page and then it was all fine again. it is the first time i got that error message here.

      • Tyler Mannison says:

        I had it too about 20 minutes ago, but like Mirri, I refreshed the page and it worked fine again.

      • This might have been just a temporary error. It sometimes happens. But please let me know about this errors. As sometimes they are sign of a problem that might be growing without me knowing about it.

      • Actually Jón, I have the feeling someone got so pissed of that they did DOS-attack. Because I got really odd reading when I tried to ping the site while I was kicked out.

      • It might have been a spam flood. The spam is growing every day. That in it self increased the load the database and the web site.

      • Alyson says:

        It happened to me too, and I wondered if we were all trying to dive into the new blog post at once…

      • M. Randolph Kruger says:

        It might be a port scan attack Jonny.

        Someone who doesnt like you or the site and setting it for a continuous barrage of contact attempts, thus blocking the server.

      • Betty says:

        Well, it happened while I was trying to open the blog. I have it bookmarked, and it wouldn’t open. So, I backpaged and got another piece, but then I couldn’t go anywhere. I tried refreshing, but that didn’t work, so I closed the browser (Opera) and later, it worked. Must have been an earthquake hiccup! Thank you…

  18. jcsager says:

    Hi. I’ve been lurking on this blog for some time, having followed the activity on El Hierro almost from the start in July. We have spent several enjoyable holidays on La Gomera and with an amateur interest in geology & vulcanology I’m naturally interested in its juvenile & rambuctious neighbour!

    I followed the earlier discussion on the possible influence of tides on earthquake activity. I believe that the general view among vulcanologists is that there is little or no influence generally.

    However when I looked at the IGN frequency plots, particularly for July and August, there seemed to be a distinct periodicity in quake numbers of around 14 days, and the peak seemed to occur more or less mid-way between new and full moon. One of the best ways to discover periodic features in noisy data is to apply a Fourier transform to the data. Consequently I wrote a small Python program to analyse the quake data in boletin_HIERRO.txt on the IGN website.

    The program counts the earthquakes in each 4-hour period from the beginning in July to the present. For each 40-day period starting at the beginning and stepping on 2 days at a time, the program performs a Fourier transform on the count data for the period and then generates a plot file of the amplitude of the frequency component versus its period for the range 8 hours to 40 days. The resulting 3D plot is in:

    http://i40.tinypic.com/29617k1.gif

    It’s an animated GIF to rotate the plot to allow a better view of it. Because that only gives a general impression I’ve also plotted the first and last spectra as 2D plots:

    http://i42.tinypic.com/2h54jrn.png

    and

    http://i43.tinypic.com/mvm07n.png

    respectively. Note that there is a strong approximately 14-day period component and lesser components at approx 3.5 days and 4.5 days. The stuff below 1 day is just too noisy to show anything significant. The 3.5 day one is probably a third harmonic of the 14-day period, as no doubt the earthquake response is non-linear with respect to whatever the forcing function is.

    I have no explanation for this – it may be tidal forcing but there may be some other reason. What does surprise me is that the gross features of the period plot have persisted to the current time, even after Bob opened up.

    • hotrod (Larry L) says:

      Does that 14 day period cycle sync up with local high and low ocean tides?

      Larry

      • jcsager says:

        Don’t know. The analysis I’ve done doesn’t preserve the phase information. I would have to think a bit more about how to use the transform information to do that.

    • Woof!

      I liked that plot, FFTs over quakes over time. Bootilicous.
      I do not have a clue of why that pattern, but the up trend was nice and visible. And Bob just made a small dip in it, and then it just continued to go up and up and up…

      Keap them coming.

      And welcome!

    • Alyson says:

      Any possibility that the magma is responding to tidal influences? Or is this an indication of water in the mantle? Or have I gotten the wrong end of the theory somehow?

      What influence does water have on the formation of crystalline geology? The Henry seamount is said to be drawing water in through its porous structure.

      Big question, maybe, but it is arising from Lurking’s comment earlier about different gases accompanying magma on its rise to the surface.

      • Alan C says:

        Water in the mantle sounds like a drastic medical condition!!
        Water can have the effect of acting as a catalyst in lowering the melt temperature hence altering the mineral composition, particularly along destructive plate boundaries with associated more violent eruptive sequences.

      • Alyson says:

        Sorry – I’ll rephrase that as a question.

        Is it at all likely that a significant quantity of water is involved in the circulation from the mantle into the El Golfo or through the island out through Bob?

      • Richard Weierink says:

        Do you mean some kind of perculator. As in cofeemakers?

      • M. Randolph Kruger says:

        In a couple of words, we had better hope not. Once that expansion process starts in a trapped heat environment of any kind it takes a great deal of time for it to cool. Rock doesnt transfer heat between itself very easily…e.g. silica hot on one side cool to the touch on the other.

        I had the same thought last week when the Restinga geyser was underway. I saw black ash coming up with it, but little to no steam and the water was about 90 degrees F. Then it basically shut down since.

        If there has been a ceiling or vent collapse inside the system it will take a tad of time for it to break out. On the other hand most of the quakes lately have been around Bob Miminus in El Golfo. It might be pushing the pressures up, and then its going to pop somewhere else. Lurk has aptly pointed out that most of the quakes are centered around Frontera and thats a bad ju-ju thing. If this invades a water system, a lava tube, or even a cave in the mountain bounded by rock on all sides it has but two things to do.

        Nothing, or escape.

    • Peter Cobbold says:

      Fascinating, many thanks.
      Difficult to conceive of tidal effects at 8km, or deeper.
      Maybe 14 day ‘rebound’ period of the bolus of magma at the MOHO???

      Maybe 14 day period of accumulation of strain : periodic stick/slip propagation?
      What happens if you separate small eqs from the larger ones? Does the periodicity persist with larger eqs, but gets lost with smaller ones? That would hint at periodicity is triggering.

    • Lurking says:

      Sliding FFT window, very nice!!

      A few posts back I managed to get the tidal data for a port in El Hierro into one plot. It runs for about 3 months, (up to Jan 2012), do the variations in your plot track with the tides? Natch those are keyed to the E-S-M positions.

      Might be handy in correlating.

      Another thing that may be useful is running a Spearman’s rank correlation on the two data sets. I don’t have a way of releasing it on a site, but if you want the tide data I can send it to you via Email. Just contact me via the Geolurking Youtube account and I can send it to you.

      • jcsager says:

        The sea tidal data would be a useful starting point, but if tidal forces are forcing the behaviour, then it seems to me much more likely that it is tides in the earth itself. Changes in the height of the water column are unlikely to have much effect 20 or more km down in the crust, but tidal forces in the earth itself will be felt well into the mantle. I’ll contact you via the youtube route tomorrow.

  19. Alan C says:

    OT – somewhat!!
    Copied from Iceland Review, short video at start
    http://icelandreview.com/icelandreview/features/multimedia//Bridge_Between_Two_Continents_0_384197.news.aspx
    November 07 | Bridge Between Two Continents
    Close to Iceland’s Keflavík International Airport lies a special bridge. It connects two continents, America to the west and Europe to the east, as it lies across the point where two tectonic plates are diverging. A few minutes southwards from the bridge is Gunnuhver, a hot spring area named after a ghost.

    Photos: Kari-Mette Johansen and Randi Jansdatter Boldevin. Slideshow: Páll Kjartansson, text: Eygló Svala Arnarsdóttir. Copyright: icelandreview.com.

    ———————–

    Close to Keflavík International Airport, at the “heel” of Reykjanes peninsula, lies a special bridge. It connects two continents, America to the west and Europe to the east, as it lies across the point where two tectonic plates are diverging.

    Although not visible everywhere, this plate boundary lies across Iceland from the southwest to the northeast and is an area of volcanic activity and geothermal heat. Other places where the plate boundary can be seen include Thingvellir National Park.

    Reykjanes is famous for its geothermal heat. The peninsula’s most popular attraction is no doubt the Blue Lagoon which was created when excess water from the Svartsengi power plant leaked into the lava field.

    Seltún in nearby Krýsuvík with its bubbling hot springs is another frequented tourist hot spot. A few minutes southwards from the bridge lies Gunnuhver, a hot spring area named after the ghost of Gudrún Ögmundsdóttir, whose nickname was Gunna.

    After having caused the violent death of a local couple, a priest was sought to get rid of Gunna’s spirit. He gave her the end of a string to which she held tight and then he pulled her into the hot spring. Since then her ghost has only been seen near Gunnuhver.

    The area around Gunnuhver is known for its vibrant colors; fiery red and bright green. The mud pools and steam vents form where steam from boiling geothermal reservoir water emanates, condenses and mixes with surface water.

    There are other attractions on Reykjanes too. The lighthouse Reykjanesviti is worth a visit and the violent surf crashing against the sea cliffs below is a breathtaking sight.

    The area is also known for its birdlife; off shore lies the islet Eldey, a 77-meter high rock which is home to the country’s, and one of the world’s, largest gannet population. The islet was put under preservation in 1974.

    Eldey is also the site where the world’s last Great Auks are believed to have been killed in 1844. In 2010 a bronze statue of the giant flightless bird by American artist Tood McGrain was placed at Valahnúkur on Reykjanes, looking towards Eldey.

    The peninsula has many other attractions, including the aforementioned Krýsuvík and the “draining lake” Kleifarvatn close by, the cone-shaped Mt. Keilir which is popular for hiking, the Salt Fish Center in Grindavík and Viking World Museum in Njardvík, to name a few.

    Really OT – can anyone (UK) remember which of my childhood’s comic the character ‘Carl the Viking’ was in !!! (Sorry Carl!!)

  20. Alan C says:

    Hey folk
    Whats going on with
    http://hraun.vedur.is/ja/strain/str_corr/index.html
    Is it stuck on 5-6th november or is this “£$%&^*” PC acting up again

  21. rosemary says:

    Thankyou also Mr Kruger. This is a good example of why I am hooked on this blog. It´s the element of surprise. Noone really knows til it happens and everyone has a different take. Am tempted to say Rock on Folks……(sorry!)

  22. RonF says:

    3.8 in the Katla caldera just now.

    Monday
    14.11.2011 17:55:13 63.666 -19.125 2.5 km 3.8 90.02 6.8 km ENE of Goðabunga

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