Posted on by Jón Frímann

Short update on El Hierro volcano eruption

This is a short update on El Hierro volcano eruption. As the situation is changing fast this past few hours.

It seems that the eruption in El Hierro volcano is gaining strength and power. The harmonic tremor on the seismomter that is on the El Hierro Island it self has started to get saturated again. It also have been unconfirmed reports of the south fissure growing in size. But so far nothing has happened in the north part of El Hierro volcano. Even if there have been many earthquakes in that area. But this area fell suspicious silent this morning. So something might be up in that area. Update 1: A string of earthquakes happened around 12:00 UTC in this area. Suggesting that something is still up there.


The harmonic tremor at 13:52 UTC. Notice how the tremor has started to saturate the seismometer. Copyright of this picture belongs to Instituto Geográfico Nacional.

What happens next is anyone guess. But people need to be aware that fissure eruptions are sometimes long in terms of the length of the fissure. But that phase normally does not last long, as soon the eruption is going to isolate it self into few craters on the fissure. I also recommend that people read Erik Klemetti blog post about El Hierro from yesterday. If you haven’t already done so.

800 Replies to “Short update on El Hierro volcano eruption”

  1. Since I invented the doppler shift theory earlier I would like to make a couple of comments.
    First of all, Lurkings speed was to high with a factor of ten.
    But that is not the important thing.
    I was wrong, utterly wrong.
    Oz beat me at my own game. Cudos to Oz!
    There is a couple of things that could be improved in his explanation, but basically he is correct at what happened.
    Phew, now I know I could never ever work for the IGN, I can admit that I am wrong (but it takes a bit of being hit with a hammer before my brain admits it).

    I will though claim to name the phenomenon to sooth my bruised ego.
    Bobsfallavindgangur (Bobs falling farts).

    1. Umm… were my calcs were off or was the result too high?

      If it was my math, please point to the area of the formula so that I may go and ruminate upon it further… there’s cud to be chewed.

      1. Since you had gotten very high speeds I used a slightly different formulation.
        First the Observed Frequency formulation, always good to have around as a reference.
        http://i39.tinypic.com/zn535x.png

        Then an inverse of the change of frequency formulation
        http://i42.tinypic.com/206bllu.png

        Then I just punched in the two known numbers (the apparant frequencies) and got a bottom speed of 160 m/s before increase. That I then cross-referenced against the distance from the thought of magma-chamber via speed x duration (before shift in frequancy). And the number seemed to be plausible.

        But, as I said, I was wrong so it is mathematical venture into futility.

        Problem I think is that you used the sub-sonic speed formulation if I remember correctly.

      3. What did you use for the speed of sound in the crust? I used an average of three values for altered basalt.

      6. May not be you, I took three altered basalt curves and back the trend down from 100MPa, 90MPa etc. down to .1 MPa (my data cut off at 10MPa) and used the average of those three values.

        I think mine was about 5998 m/s.

  3. What about the chance of a Tsunami forming now under the ocean ?

    Is this a ridiculous question or could it become fact.

    2. The chance of tsunami is very, very low.
      This eruption is more a question of a possibly spreading fissure, a large crack suddenly appearing belching lava and ash. It is a dangerous time till the fissure opens and people know where it is. A little like what is shown, if one were to Google Krafla fires, but much smaller.

      1. Pretty much yes, do not be ontop of the fissure when it opens up. Thing is just to know where it is…

        Project for tonight, what is the chance of someone actually standing ontop of it when it horks open? Hm…

    3. Yes. There Can be Tsunamis due to the unstable geology in the islands. WE don’t know if these continuous tremors -with volcanic eruptions- and quakes will cause a landslide. There is a Fissure running through Cumba veheu on la Palma. Several documentaries exist on the net in regards to said theory. Is it possible, I THINK SO. La Palma is only 90km to the North of El hierro. Scary.

      1. Stop unnecessary scaremongering, this is absolutely unfounded and adding to the psychical strain on people of El Hierro. Many time in here it’s been explained that the probability of El Hierro causing landslide on Cumbre Vieja is very very slim, nearly zilch, zero, nada, nix…
        There is no connection between El Hierro and La Palma.

      2. Concur. If it weren’t for the fact that this idiot is trying to maliciously spook people I’d be laughing my arse off.

    4. Judith-Its universally accepted that the threshold most of the time for these is about 6.5. The sea floor has to subside, rise or in the case of a megathrust such as Chile or Indonesia, snap from being impinged on another plate back into place. Not going to get that from a 4.4 mag quake. Might see a couple of inches on the beach if its close and it has all those characteristics.

      In addition, its the type of quake that caused it. Magmatic quakes rarely (I cant remember any) get beyond 4.5 unless its D-day in the eruption and then just about anything can happen, but most of the time that happening is above the local surface and causes the volcano to explode and even then there are other things that happen to cause it.

      Tsunami threat-I refer you back to the papers about the overburden of the flanks of the old volcanoes on the island. The mountains are almost sheer and they have been undercut in inverted “U” and “C” formations. The estimated force to pop them loose is in the 5.5 range and maybe not even then. It has happened before and carried 1 km blocks out to 35 kms with the total distance on the La Calmas side being out to about 135 kms. Thats the biggest threat out there for tsunami right now. Later as this thing manifests itself something might happen like the fissure opening from Restinga out to El Golfo but thats a long hard reach too. I suggested that but just got in and started reading as I posed it to Erik K and Boris B. Have to see if they answered yet.

      If you are on the island my suggestion is that you leave. You can be sitting on another island watching all of this on local TV and sucking on a fudgesicle all the while being safe in doing so.

      1. I have to correct you on one thing.
        But first, let me say.
        WHAT I WRITE HERE WILL NOT HAPPEN AT EL HIERRO!

        In very explosive volcanos (Krakatoa) the internal pressure can build up so much that the ejective orifice cannot handle the strain. Then the a new much larger orifice will be created explosively (7M for Krakatoa). In Krakatoas case that explosion laid bare the magma-reservoir causin a secondary explosion ranging between M8 and M9, that caused one of the larger tsunamis recorded.
        Krakatoa and El Hierro are A) Not the same type of Volcano, B) El Hierros magma-reservoirs are much much to small, C) A rifting fissure volcano cannot build up sufficient pressure for that to even happen, the rift will open like a zipper long before releasing the pressure.
        This was only posted as a comment to the above comment and has nothing to do with El Hierro.
        THIS HAD NOTHING TO DO WITH EL HIERRO!

      2. OT re Kraktoa as well – and please note I say stupid things sometimes – my understanding of Krakatoa is that it grows constantly from a single point at the top of a conical volcano. Eventually the weight of the cone, and the narrowness of the ‘chimney’ build pressure underneath. I visualized that it actually lifted, after bumping a bit, and water got into the magma underneath, so that it blew to high heaven back in 1883, or whenever.

        El Hierro has many magma routes, pockets and mixed geology so is not at all like Krakatoa. It grows new land as it is doing to the south with the Bobs. It is a rift and can open up along a line, or from several different cones at a time.

        I tend to worry a lot, and would have left El Hierro just in case, if I lived there, because it is not known how it may mix its different magmas and geologies.

      3. No, it did not lift from under, that would have taken so much energy that the actual lifting would have been an even larger event than the explosion.
        No it blew up as an overpressure in the orifice.
        And the orifice was not very thight when it went boom.
        But you are right, size and buildup was a large component in the Krakatoa destruction.
        And we should remember that Krakatoa has more or less been permanently erupting with intermissions for more then 100K years, and had more than 2 exlosive destructions. It is believed that at going rate it will explode next time in 10 to 20 Kyears.

  4. A couple of days ago, a Mag 4.3 (11/2/2011 7:54, event 1109562) and 4.4 (11/2/2011 18:10 event 1109738) were reported by IGN. They were later revised into a single 4.3 at 11/2/2011 18:10 as event 1110025. The 11/2/2011 7:54 4.3 has disappeared and no longer shows up.

    Dumping my old data file and cumulative quake energy shows a different curve, but with the most recent quake, still gets you to the same spot.

    http://i43.tinypic.com/210c83t.png

  5. @ Lurking about Henry

    I posted this some time ago but not many noticed it I think so here it comes again.

    From http://goldschmidt.info/2007/abstracts/A496.pdf , an abstract:

    “How can Recent fluid venting at Henry Seamount be reconciled with its early Cretaceous age? We propose that hydrothermal circulation within the Jurassic oceanic crust around El Hierro is driven by a mechanism similar to that proposed for young crust of the Juan de Fuca ridge flank
    (Fisher et al., 2003), the ultimate heat source being the hotspot beneath the western Canary Islands. Henry Seamount may thus work as a “breathing hole” where fluid discharge is facilitated by a rather thin sediment layer compared to the adjacent seafloor covered by thick impermeable sediment.
    Recharge may occur at adjacent basement outcrops such as the flanks of El Hierro island. Our results indicate that hydrothermal circulation through seamounts is not confined to young warm ridge flanks but may be a widespread phenomenon on the ocean Floor.”

    1. How did you get access to CJUL? I though IGN password protected all the new seismographs, to prevent their servers from crashing.

      1. I don’t ask such questions in public.

        I think that presidents use the official term “deniability.”

      2. Dont ask no questions and you wont get no lies told to you…..

        LOL Lurk. How are the boys?

      3. no trick or hack: I was just was on that page when they came out with password restrictions , so I am being careful to preserve my connection to it (CJUL) … can’t get to other restricted sites through this page however ….

  7. Carl

    But what about a larger quake .

    Was not the Tsunami in Japan caused by an earthquake under the sea.

      1. You’ll never move a comparable volume of water with a quake related to the current activity around the Bobbies. Speaking purely tectonics/seismicity.
        If the current activity lead to a slide into or under the sea, you could generate a wave, but no way a monster like in Japan. Older posts of the guys that take a lot of time with brilliant explanations like Lurking and Carl should allow even non-specialists to realize that.
        The situation is to be taken serious, but Hierro is a very small thing at global scale. Not to be misnderstood by the ones directly concerned. I know your personal world is right now being troubled an immense way.

    2. If I remember that was not caused by this type of earthquake to beginn with. If mind serves that was a slip fault of rather stumping size lifting a big part of the ocean, and it was about cirka 1 048 576 times larger in energy content…

    3. The Japanese Tōhoku earthquake lifted about 145 km³ to 214 km³ of water and sent it careening off to kill people.

      The entire island of El Hierro is 159 km³. You are gonna need a hell of a lot more than a Mag 4.4 to cause a problem.

      Meanshile… we get bubbles!

      http://i42.tinypic.com/14ddjko.png

      1. Okay, I am probably pretty blond right now… But bubbles?
        Something tells me that if I do not get it, there are probably one or two more here that have missed bubbles.

      2. The cavitation/oscillation thing of the tremor source.

        The quake seemed to be about the right spot for the increase in signal.

        I think bubbles are cool. Much more happy and non-threatening than an impending eruption.

      4. Tsunamis do seldom occur below a 7.0 magnitude. All these tsunami stories for the USa are making me nervous. The people really at risk with a huge half mountain collapsing El Hierro in the sea will be the neighboring islands and the African coast, not the USA/ This stupid science fiction documentary of the BBC is making people sick in the US. I do understand them, if you dont know anything about it and the BBC aired it , it must be true.
        If, if, and then if and if and if , a chain of 5 events only appearing every 20,000 yers , yes.
        You will certainly have more chance to wibn the lotto then having a tsunami wave in the USA !

      5. But interestingly the BBC is not reporting the eruption at El Hierro its website for the UK (to the last time checked at 20:00 this evening).

      6. I have my own take on the dynamics of tsunami.

        The Sunda Megathrust and the Japanese quakes were both launched or formed as planar waves. That means that each location on the wavefront was moving parallel to the location next to it.

        An island dropping a chunk in the water is going to behave as a point source. It’s going to be several wavelengths before that circular expanding wave turns into a planar wave. Until that time, the energy per foot of wavefront is going to drop as a function of the distance from the place where it originated.

        If you calculate the volume of the wave, and then expand that volume based on the radius (using the Pappus’s centroid theorem), you can calculate how the energy will drop off.

        Translated into the percentage of the initial wave-height, you get this curve

        http://i39.tinypic.com/dd2tty.png

        Now, where you are on the curve when it becomes a planar wave really depends on the wavelength, which is a function of the depth of the water.

        I wont try to duplicate it, but you can find it here:

        http://www.seafriends.org.nz/oceano/waves.htm

        I also don’t know at what point tsunami’s go from a “near field” style of propagation to “far field”. But this is about when it would become the planar wave.

      7. Armand is right and was based on La Palmas, not El Hierro. The threats for El Hierro going flank fault are only just being understood. And yes about every 20,000 years give or take.

        It does happen though and as I understand it reflectors are being placed on the flanks on the SW corner for lasers to hit them and determine if there is slip and by how much.

        Volcanoes you see and you get out of the way of them. A flank failure could come from too much rain. They simply dont know even though the papers call about 50% of the SW corner “overburden” and “beyond the angle of repose.” When thats said you pay attention and prepare, its all you can do.

    4. @Judith. The Japanese quake occured on a convergent plate boundary between the Pacific Plate and the Eurasion Plate. Larger EQs are tectonic and occur when the plates move against eachother; unfortunately this is not a smooth motion.

      The Canaries are situated on the African Plate, not near a plate boundary. So it is highly unlikely that tectonic quakes would occur there. The current EQs are magmatic in nature, caused by local rock fracturing round the magma reservoir, so tend to be a lot smaller.

      In the extremely unlikely event that a tsunami was caused by El Hierro, it would probably be small and most people would get ample warning.

    1. On this blog that was seen the day it was put on Youtube 🙂 lots of people who live in Iceland post here.

      1. Oh no it wasn’t it was on Erik K’s eruptions blog . Got myself mixed up there.

    2. I believe it has but it is still a good one to watch Andy. …and whilst we are on the subject Katla is having a very poor attempt at a party as it is Friday night.
      http://en.vedur.is/earthquakes-and-volcanism/earthquakes/myrdalsjokull/

      For people new to Jon’s Blog, Katla and other volcanoes on Iceland tend to Party on Friday nights and spend the weekends with indigestion and hangovers….We always watch in case they start Vomiting :)…… Etna tends also to go into a Paroxism at the weekends to !

      2. Ursula you are right 🙂 All is quiet in Iceland.
        Also for those readers who are new here, this web cam is truely beautiful and of ten shows the Aurora well. It is the Imagine Peace Tower and tonight I dedicate this link for all people on El Hierro. May they sleep in safety and soon get their lives back to normal and be free of worry.
        http://www.earthcam.com/cams/iceland/reykjavik/

  9. Grateful for considered responses re Tsunamis and other ghastly possibilities. Husband set off from La Gomera 2 days ago and is at sea at the moment. Hopefully well away from any danger zones. But totally out of contact. Have been watching your very interesting blog, and developments, avidly.

    1. Hi Christine, I am sure I speak for everyone here and hope he is well away from the danger zones too.

  10. Okay, calculated the chance of someone being killed by a hypothetical Baldrick.
    If the ground opened in 1km long fissure and we then add an exclution death zone for a thousand metres in all directions we still get that the chance of being killed is 1 in 24500. I still think that a car accident while fleeing would be more likely to kill you.

    1. Depends on what you are fleeing… if it’s an armed husband I would think that the probabilities are higher.

    2. Next time I need a risk analysis I call You. Last one I ordered took the guys a fair moment, and we went over the result more than once… 🙂
      Shleep well Jonreaders.

      1. I would not put that one in the books, it is just a bit of simple math. All you need is area of the island and the population number.
        What you are doing is much more complex.

        But, there is always the holy shit factor of risk management.
        We all know that the fissure will open up at the Photographic Competition Festival Banquet hosted for free by Senor Armas.

      6. 🙂
        I was so much of kidding. It was clear you are just playing around a little bit. If risk management was so easy I’d have no job… But it’s always nice to break it down to the basics. The idea behind is in fact quite simple. When I teach risk stuff (only once every year, am absolutely no more academic employee), I like to make an example with the landing of Godzilla ore so. Problem is this young dudes don’t know the real Godzilla anymore… 😉

      8. Sometimes simple playing around with math really tells you something.
        In this case it told us that more Hierrans are likely to die from a car accident (statistics from Spain traffic yearly death rate) this year than a rather largish fissure showing unexpectedly.
        I wanted to put things into a bit of perspective.¨

        Actually the numbers are a bit tilted, I counted that everything 1km out from the zone would get znookered by the fissure. They would most likely be safe 0.1km out…

  11. Border Earthquake, iron of 4.4 has been felt in La Gomera and the municipalities of Santiago del Teide and Arafo in Tenerife.
    Many residents of coastal border and stay on the streets with real fear of returning to their homes, fear is heightened to see the swing of Security Forces members to the area and there have been several detachment.

    The neighbors feel anger and helplessness that no one says anything
    http://www.noticiasgrancanaria.com/2011/11/el-terremoto-de-el-hierro-se-siente-en.html#!/2011/11/el-terremoto-de-el-hierro-se-siente-en.html

      1. A El Hierro quake of 4.4 has been felt in La Gomera and the municipalities of Santiago del Teide and Arafo in Tenerife.

        Many residents of coastal towns are living on the streets with fear of returning to their homes. That fear is heightened to see the Security Forces members to the area and there have been several detachments deployed.

        The neighbors feel anger and helplessness that nobody says anything.

        Yeah Luis I agree with the people, they should up the info stream at all of the governmental agencies. Lets face it, its a tourist town and island. No one is going to want to visit it if they have a decent chance of dying except for crazy wanna see it types.

  12. 4.4 a 22 kms. de profundidad. Muy cerca de la costa. La gente lo describe como el más fuerte vivido hasta el momento, y no acaban de estar de acuerdo con la magnitud.

  13. The 4.4 has now been moved from W to NW Frontera and from 21 to 22km. Looks like the rift has widened across this area, at depth.

  14. If the steam appears at the Calmas horizon, Raymond the Frenchman will have the golden picture ! He is now sleeping with his tent open and with a clear sky on top and a volcano monster below him. Nobody jealous here ?

  15. From avcan.org: http://www.facebook.com/pages/Actualidad-Volc%C3%A1nica-de-Canarias-AVCAN/163883668446

    “AN EARTHQUAKE OF MAGNITUDE 4.4, WITH EPICENTER IN FRONTERA, HAS BEEN SENSE IN LA GOMERA AND TENERIFE…

    04-11-2011… 21: 18 — Ministry of economy, finance and security has also been felt in Arafo and Santiago del Teide (Tenerife) and Valle Gran Rey (La Gomera) IGN has confirmed to the direction of the PEVOLCA that there has been an earthquake of magnitude 4.4, West of border, with a depth of 21 kilometres.

    This earthquake has occurred in an area close to the coast of the Hierro municipality and has been felt, in addition to the three municipalities of El Hierro, Arafo and Santiago del Teide (Tenerife) and Valle Gran Rey (La Gomera), according to calls received in CECOES 1-1-2.

    This movement has caused some landslides in the core of Sabinosa, and on the slopes in the area of Guinea.”

    Translation by Facebook.

    1. Forget Facebook Karen… send me the text so I can give a decent translation of it. Sometimes its a bit nervous and jerky but its better than that that you have.

      Define….landslides !

      1. It was Avcan’s official facebook page. Follow the link provided for the original text.

  16. Let me think…..Mmmm….No! This area doesn´t like me right now, especially the old fissures of El Julán….

    1. ¿No sería más la zona del desprendimiento del Golfo? También cerca de Sabinosa, al otro lado del valle se mencionaba desprendimientos…

      Isn’t that rather the area of the landslide of El Golfo? Also close to Sabinos, at the other end of the valley they mentioned landslides…

    2. No, scale has automatially shrunk again after the 4.4 quake earlier this evening – see comments from Carl on the previous page.

      3. It seems there has been automatic rescaling. The tremor is not less than before – if you compare CHIE e.g. to EHIG at La Palma.

    1. It’s kind of funny though, we’re giggle translating AVCAN fb into English and they are now in the one-before-last thread of comments giggle translating Jon’s latest post into Spanish. Also Erik K’s blog…

    3. And now they are reporting that from La Restinga and Puerto Naos they can see something shining/incandescent in the sea. Although it is not confirmed for the moment…

  19. The AVCAN talks about”two volcanic systems INDEPENDENTS … they are pre-eruptive symptoms clear that soon (24-120h) may have another eruption in the north of the island, besides which there are already underway in the south of the island by the area of ​​the Restinga .”Enrique .

    1. I wouldn’t think about two different and independent volcanoes here (though not being an expert), but more about two different fissures of the same volcanic system which could erupt at the same time (sth. like this was e.g. going on during parts of the Krafla fires volcano-tectonic episode in the 70s/80s in Iceland – Gjástykki and Krafla caldera, as far as I remember).

      In Hawaiian volcanoes, there are sometimes also 2 eruptions going on simultanously in the same volcanic system. http://www.dailykos.com/story/2011/03/07/953607/-New-Kilauea-Fissure-Eruption!-Movies-Images

      1. Not two differents volcanos. One volcano, but with two volcanics differents systems (enjambres). One in the south, la Restinga, and the other one in El Golfo. That´s what I understood.

      3. I think, we have been talking about the same thing. Could of course be two different magma reservoirs in the same volcanic system – there has been talk about that here before.

  20. At the moment, I would not drive on the Calle de las Puntas if not really necessary. It is beneath (and not far) from the scarp where rocks are said to have fallen.
    See my comment from 22:55 with GE picture.

  21. Friday
    04.11.2011 23:00:13 64.499 -17.680 1.1 km 3.0 90.06 6.4 km ENE of Hamarinn

    1. And it’s confirmed.

      But as up to now, I don’t see a lot of water coming down Skjálfandafljót – which should be an indicator. He is on the contrary the only one which is still at “green – normal flow” in the region. And the others have a lot of water due to bad weather, I’d presume. http://www.vedur.is/#syn=vatnafar . Skaftá could be an indicator, too, but I can’t get in to the data about her. And Tungnaá has being going up (Vatnshaed = water height) by 50 cm yesterday, but the publicized data stop at midnight. http://vmkerfi.vedur.is/vatn/VV_Frame.php?r=16480&load_graph=1&direct=1&station_id=218&station_name=Su%F0urland&page_id=281

  22. As that last EQ was felt distinctly on Tenerife I compared these two: 11/02/11, 18:19, which was a Mag 4.4 until recently but revised to 4.3 now and the last one 11/04/11, 20.21, called a Mag 4.4 (so far). What do the experts think, do you see a difference of just 0.1 Mag here? the oscillations in the first one go over 5 hour lines either side in the graph while the new ones span 8 hour lines to either side. To me the one from today looks a much higher Magnitude. Could there be reasons why EQ waves of almost the same strength at source might arrive at a given distance differently in different events?

    http://i44.tinypic.com/2vw6zgz.jpg

    To find the relevant graph of an earlier 4.4 I used the ign search feature. It came up with 3 EQs higher than 4 from 01/10 to 04/11 (4.0, 4.3, 4.4) – I thought there had been more (even discounting the one Lurking already said, on the morning of 02/11).

    2. MACI is a seismic station over at Morro de la Arena, Canary Islands, it’s part of the IU network and does have data available from Iris BUD.

      Seismicly, it is locate at 1.43° and 1.44° from the two quakes. The Mag 4.3 (the earlier one) is about 1/100 of a degree further away (not very much).

      Here are the traces of the two quakes as they appear there. Blue – Vertical, Yellow – N/S, Purple – E/W.

      The vertical and horizontal scales are matched in these two displays.

      http://i41.tinypic.com/214pcpg.png

  23. I am off to bed now.

    A good and quiet night to everybody and especially to the people on El Hierro!

  24. It did last somewhat longer, yes, but I mean the amplitude of the initial big (P-?) waves.

  25. http://www.gobcan.es/noticias/index.jsp?module=1&page=nota.htm&id=144473

    Closes the access road to the Roquillos tunnel and struck 11 Las Puntas homes at risk

    04-11-2011… 23: 57 – Ministry of economy, finance and security
    They are preventive measures that will address tomorrow in two meetings of the Group of scientific work and Steering Committee
    The direction of the Plan of Civil protection by volcanic risk (PEVOLCA) has decided this evening close access to the Roquillos tunnel road until 7.30 in the morning as a preventive measure before the earthquake of 4.4. that it took place at 20: 36 hours at border, and the possibility that could increase the magnitude, according to the warnings of the National Geographic Institute (IGN). The opening of the tunnel in the morning will be done with surveillance and security measures.

    It has also proceeded to the eviction of the 11 homes of the tacks, greater risk of being affected by landslides.

    These preventive measures will be discussed tomorrow in two meetings of the Scientific Committee and Steering Committee to assess its maintenance or making other decisions necessary depending on the situation.

    Earthquake
    The Coordination Center for emergency and security (CECOES) 1-1-2, dependent on the Ministry of economy, finance and security of the Government of the Canary Islands, received 20: 37 21: 28 tonight 45 made by inhabitants of the three municipalities of El Hierro and calls related to the earthquake that occurred this evening on the coast of the island.

    Also in that same time interval, the Canary Islands 1-1-2 handled some calls from the municipalities of Arafo and Santiago del Teide, both located in the South of Tenerife, and Valle Gran Rey La Gomera.

    The most important incidents related to this phenomenon have been associated with some detachments located at the heart of Sabinosa, and in the area of Guinea, without consequences.

    In this sense, the IGN has confirmed to the direction of the PEVOLCA that there has been an earthquake of magnitude 4.4, West of border, with a depth of 21 kilometres.

    1. When did they give Bobzilla a watch? C,mon, guys, admit it. People can’t safely use the tunnel now.

      I am shocked that a mag 4.4 at 21 km could be felt on the other islands. That gives you pause.

  26. 11/04/2011 … 23:57 – Ministry of Economy, Finance and Security

    Preventive measures are being discussed in separate morning meetings of scientific working group and steering committees.

    The Director of the Civil Protection Plan for Volcanic Risk (PEVOLCA) has decided this evening to close the access road tunnels until 7.30 am as a preventive measure due to the 4.4 earthquake which took place at 20:36 hours. The possibility that a larger quake could occur according to the National Geographic Institute (IGN) required the notification to the public. The opening of the tunnel in the morning will be done with surveillance and security measures in place.

    This closing order also requires the evacuations of 11 houses at points that were more likely to be affected by landslides.

    These preventive measures are discussed in separate morning meetings of the scientific committee and steering committee to assess maintenance or making other decisions that may be necessary depending on the situation.

    Earthquake
    The Emergency Coordination Center and Security (CECOES) 1-1-2, under the Ministry of Economy, Finance and Security of the Canary Islands, received 45 calls by inhabitants of the three municipalities of El Hierro requesting assistance between 20:37 and 21:28 tonight. All related to the earthquake that occurred this evening on the coast of the island.

    (didnt specify what the problems were… Bet it was minor landsliding)

    Also in that same time slot, the Canary emergency line 1-1-2 received calls from the municipalities Arafo and Santiago del Teide, both located in the south of Tenerife, and Valle Gran Rey in La Gomera.

    The most important incidents connected with this phenomenon have been associated with some landsliding located in the heart of Sabina and in the area of ​​Guinea, without consequences.

    (Ground started moving, major pucker factor incident. I get that a lot during floods around here. Water starts rising and they start calling)

    In this sense, IGN has confirmed at the direction of PEVOLCA that there was an earthquake of magnitude 4.4, on the western border of El Hierro with a depth of 21 kilometers.

    1. A difficult situation to call, by any stretch of they imagination… there is no template to help in the event of planning for emergencies such as these. At least in Iceland, indonesia or California, the dangers have been discovered over the course of centuries. But to be in an unprecedented situation where the ground may literally open at your feet? There is no right answer at that moment, for the way is uncharted…

      This is an emergency coordinator’s nightmare. On any given day, even as a volunteer, I am attempting to gather information regarding known risks and the possibilities that surround them. It takes me sometimes months to collect and analyze data, yet I still am cautious in sending out my opinion regarding risks because I know how little I know. How much harder it must be for these first responders and the people they serve, who have no known event with which to compare this?

      Thank God for men and women such as those who post here and on other excellent sites, volunteering long hours to analyze data, sort through theory and fact, all to help shed light in a dark time!

      I do pray for the people of the Canaries at this time. Regardless of the events which may occur or not occur, it is certainly stressful and dangerous for them… Perhaps what we and others post here will help them – and may even save lives!

      1. Milagra,
        A local volunteer system seems to me to be very good idea -we have nothing in UK like that. Was the scheme set up since July’s earthquakes started?
        Iceland’s ‘phone companies install webcams around an eruption which can be a big reassurance to local inhabitants – ‘seeing is beleiving’ as well as a source of information for people such a yourself. So I am a little surprised that none have appeared.
        Peter

      2. Actually I am in the United States, in rural Texas; we have an extensive network of emergency volunteers organized by the local populace, with help from local authorities. The system is designed to train and equip volunteer emergency first responders and have them work with local professionals. However, the volunteers frequently equip and train themselves at their own expense.

        It is a labor of love, for we wish to help ourselves and our neighbors as much as possible in the event of any emergency. I myself am trained as a volunteer firefighter and am currently slated to take my Emergency Medical Technician Basic test on the national registry. In addition to that I am an amateur radio operator, volunteer local emergency planner and trained weather observer for the fire and tornado seasons. We have no official local weather services or stations within 60 miles, so the volunteers observers are critical during severe weather.

        Since we are a lightly populated rural county with small towns, the majority of emergency services are provided by volunteers such as myself. We greatly appreciate the professional medical and emergency first responders we do have in our little county here in Texas – and we are very proud of our volunteers!

      3. Oh and I forgot to mention – as a Texas Woman, I do it all in lipstick, lace and cowboy boots! 😉

      4. All I have is a chainsaw and a shotgun. One is for cutting my way out of the house and the other is for keeping the looters at bay. Do you have any idea how many round you have to use to cut a branch in two?

      5. Lurking, a question here since you normaly have a rather calm head.
        Do you guys really need the guns as safety equipment against natural hazzards?

        Personaly a gun would be the last thing I would have handy in an emergency kit. The only conceivable thing I could think of with a gun would be to hunt game for food. I would not feel any need to have one around to use on my neighbours. I guess I am very european here, but do you americans really need them? I am just culturaly curious here.

  28. Hello ppl!

    Seems that Bob got another swallow of hot magma 😀 is a thrue Oktoberfest!!! After all, the start was on October, right?!?
    I wonder about how deep is his thirst?
    On the other hand these burujas aren’t they aligned as an iso line? Of course a nice contour of the historical landslide of El Julan??

  29. I do think that new fissures are opening up in El Hierro. But so far all of them have been in the ocean.

    The earthquake activity is a indicator of this.

    Have there been confirmation of new vents NW of Frontera ? In the ocean that is.

    1. Jon,
      I don’t think this has been confirmed – some material was collected by the survey ship but I’m wondering if this may have been carried by the current circling the island – from El Julan?

      1. So far from what I’ve seen on the news, nothing has been confirmed off the northern coast, however, they have been concentrating on the area off the coast of La Restinga. I think (and could be wrong on who) it was crew from the Ramon Margalef who mentioned having seen something off the northern coast.

  30. See page 17 and Fig. B – look familiar ?? Graphic of El Julan landslide area

    ‘Landslides and the evolution of El Hierro in the Canary Islands’
    Gee, Watts, Masson, Mitchell 2001 Elsevier Science B.V.

    I’ve referred to this in the past but probably a good read for those interested in the geology of El Hierro

      1. Thanks Milagra – have to save that one for a quiet day ! Took a quick look at it though – here’s one graphic showing landslides. The one at El Golfo is very flat – where the bulk of EQs have occurred. Strange why the current eruption has come through the ridge at El Julan.
        http://i39.tinypic.com/zty7w8.jpg

      1. There are some large submarine pinnacles too in roughly that region – in that paper you cited.

    1. Yep – I guess so. I think that guy in the tent at the top of El Julan may get a good view in the morning! For now – I’m away to my bed – catch up tomorrow. Cheers !

      1. Yes agree – a cheap way to monitor surface events. Or at least to know they have not got closer to land! At night I guess they would pick up hot gas on land too.

      2. Voila!
        That’s means high end technology, after all for a new baby born a thermometer it’s a must have 😀 .
        Of course, a sheep story for the night might help too 😛

        Ups! that’s remind me that all babies do cry endlessly at night…

      1. Great plot.
        I don’t think I quite understand what relation you see linking Henry sea mount to the lack of shallower quakes.

    2. @ Lurking,
      Hate to say this because your plots are such a valuable aid to visualisation,
      but I think the psots are displaced to lower depthd by about 5km, compared with IGN plot:
      http://www.01.ign.es/ign/resources/volcanologia/jpg/Eventos_HIERRO_2011.jpg
      The top of the July swarm was at about 8km. vs about 15km in your plot.??

      Much of that swarm was in the sendimentary rock and crust as MOHO is at about 14km at periphery of Hierro. Allowing for sinking the MOHO centrally could be around
      3km deeper, say 18km. So much of the July-Oct swarm was in sedimenrary/upper crust. My interpretation is that the old magma intrusions- a labyrinth of sills, dykes, all small scale – fractured under strain.
      Lack of support from sediments render them susceptibel to low level strain?
      Peter

      1. @ Lurking.
        Profuse apologies, the plot is fine – parallax problem here.
        Is it possible to shadow the spots on one wall – as Korf did for Eyjaf?
        But comments about sedimentary etc stand.
        Peter

    3. Thank you. A great plot Nasty feeling that the shape of the magma reservoir might be becoming clearer.

      Do you know where the echo chamber that the chief scientist mentioned would be? The one she said the larger EQS in the NW / W were occuring (sorry a few threads back, otherwise I would provide the link).

    4. Falling Fart Bob 🙂

      There is something that is bothering me no end with the pattern. But I cannot really put my finger on it.
      I think that this eruption will go on for a long time. It seems to have built up one hell of a deep feeding dyke down below. I think El Hierro is setting up for a direct feeder from the Hotspot, and then it could go on for many many years. And that would actually be substantiated as a behaviour by historic data.
      El Golfo after all grew into unbearable size in just a few eruptions causing the collaps.
      So here is my new worst case scenario, either Bob, or a new Bob under El Golfo, will be going for years, building up in the end to a plus 1km cubic eruption. But, this is wild guessing.

  35. Surely now all these earthquakes will have weakened in some way the infrastructure of the base of the island.

    Is this not more of a danger now she may collpase.

    How much more pressure and movement can the base of El Hierro take ?

    1. Impossible to tell but I wouldn’t image that a couple of magnitude 4.4’s will knock it down. 7’s or 8’s which are theoretically possible through plate techtonics and are orders of magnitude more that we are seeing here through magma movement might move some things but we are not seeing that. You also have to remember that El Golfo has already collapsed so much of the unstable areas of the island are already in the sea.

    2. Judith, stop worrying about that. Most of the island has allready collapsed, and collapsed matter cannot collaps again. There are a few areas that collaps, but on a small scale. You are worrying to much. Relax.

      Secondly, if you see a mag 5.5 or higher, then you could perhaps get a small collaps.

    3. The base of the island will be pretty solid. And don’t forget that the base spreads along way out to sea. Any landslip will be small and local – not good if you have property in the wrong place, but not a major risk to the rest of us.

  36. Just posted on Avcan

    Good news, isn’t rhyolite as stated: “claims (María José Blanco) studies that have been made of the pyroclastic in one center of Huelva, another of the CSIC in Barcelona, and two more in the U.S. and in Clermont Ferrand (France) indicated that it found is a type of lava much less explosive than rhyolite claiming the researcher at the University of Barcelona.””They are traquitas, with a lesser degree of burstiness.” “In addition, he insisted that depth in which there are emissions not entail danger.”
    16 minutes ago · Like · Original

    1. Nice. A rock that is chemically virtually a rhyolite, with similar structure and alkaline mineralage… including feldspar. It’s gonna boil down to what the actual percentages are.

      And this better how?

      1. No idea. Especially as we do not know if they are even looking at the same samples, nor how big the samples are.

    3. They continue talking like an old medicine man in a bad Winnetou movie. I always miss more detailed explanations. We only get superficial part-conclusions. Either they are bad at simplifying their scientific results, or they are not sure about their work. An other possibility of course is that everything is perfect and I shouldn’t rely to much on what is in the media and even here. Thé risk with these modern info-sources, and we know it as we consume them.

    1. Over? I thought that we had been told that the sea was too acidic or too hot. Has the composition of the sea changed?

      1. Margalef has a hardened hull judging from the videoclipp. It has a second external hull layer so it can take a lot more crap than normal ships.
        And secondly, I think they happily take a bit of risk to actually get to know what is happening.

    2. Nice to see that picture as it has really emphasised to me quite how close to land these disturbances are. The boat gives a good reference for distance.

  39. By the way, if the seismograph was automatically resized yesterday then the tremor is still increasing rapidly as it is ‘clipping’ again.

  40. It looks like tremors at CHIE are saturating seismograms again, despite yesterday’s gain rescale.

  41. and another large quake. 3.9
    1110408 05/11/2011 09:44:44 27.7841 -18.0497 20 Sentido 3.9 4 NW FRONTERA.IHI
    In earlier days it seemed when the tremor was high we didn’t get so many large quakes. Does this mean we could soon see juvenile bob appear.

  42. =======
    Son de Bueu says: November 5, 2011 at 09:33

    Ramon Margalef OVER Bob..
    =======

    Note this is potentially hazardous.

    Seawater full of enough bubbles can have its density reduced to the extent that a ship cannot float on it, so the ship sinks. There has been suggestions that some areas (Caribbean) have discharges of methane (possibly due to degrading methane hydrates) that may have done exactly that.

    1. As a Ship’s Captain I can agree. Vessels have been lost accidentally anchoring on gas pipelines due to loss of buoyancy in gas saturated water. I have had similar concerns when operating an ROV on submarine volcanoes in the past though thankfully dormant it is still part of the risk analysis

      1. Oh, we have gained in knowledge again 🙂
        I guess we will have a plethora of questions for you about ROVs and stuff like that.
        Welcome to the crazy bunch in here!

  43. ====
    Lurking says: November 4, 2011 at 19:36

    By the way Oz, I do agree with your mechanism.
    ====

    Ye gods, you aren’t supposed to say things like that on a blog!

    Of course there are several other plausible scenarios, differing only in details, that use the same mechanism to generate chirps like this.

    One item I keep forgetting to add is that the 48min (?) repeat, as noted by Carl, would be typical of a geyser-like system (think Yellowstone “Old Faithful”). A more or less constant flow of more or less similar composition in a system would often produce this sort of regularly pulsed sequence.

    One thing does slightly puzzle me is why very accurate location of the resonating pipework isn’t easy. Even (relatively simple) filtering on these long period events would screen out all the noise, let alone more complex (but ancient) digital auto-correlation-type filtering. It would for sure be nice to know where the plumbing is being actively used!

    PS. Given the extended (many hours++) activity of the long period oscillations one would have thought that hydrophones would have a reasonable chance of easily detecting the subsonics, and these could be towed around likely sites to give accurate locations. I rather doubt they are in the 20km depth range.

    1. Yes, I find a geysir-like mechanism attractive. We saw no sesimic evidence for movement of magma upwards from the deeper EQ focus (7-10km) before Bob erupted. Some nearby shallow EQS yes. These may have opened up access of seawater to pre-existing magma at shallow depth, possibly residual from the eruption that created the lava flows of Tacoron south of El Julan, 12k age. The mechanism for the seamounts may apply: effectively a U-shaped water flow with the cold down-feed kept in motion by the less dense hot water and steam in the upflow. Bob is the upflow of course. Quite possible for this to be on km scale I guess. Hence ca 48 minute period? The greyish patches os stin in Bob look tightly focussed with sharp edges – suggestive of a jet of water with little gas content. That could represent the column of hot water being ejected.
      So what has thermal imaging told IGN about the grey burp temperature?
      What is the time of occurrence of these grey burps compared with the regular tremor pulses?
      PS What about Konstatinou’s semblance method for locating tremor?

    2. Yes, it is quite easy to locate the tubing. But for that we need the raw-data.
      If someone finds it I have the programs to do it here at home.
      Would just take minutes really, unless I need to parse the data first into a usable format, then it would take hours since I am not a programmer.
      But here is what I think, the equipment is a bit low-tech. I think even the “new” equipment is old gunk that they have moved from other locations in mainland spain. So it might be a no go anyhoo.
      But if you find data I could give it a try and plot it into a map.

  44. Seems that little Bob is thirsty, yet another suck of magma.

    So nobody ever considered a thermal camera there around???

    1. Or teaching Bob to drink a bit slower so he does not burp so much! He’ll be sick soon.

      2. Maybe, but it would be an invaluable source of information for the scientists working on this eruption as was the camera of this type installed at Eyjafjallajökull last year.

  46. A banner at Diario Hierro http://www.diarioelhierro.es/ says:

    “El Pevolca se reunió esta mañana, a las 12:00 horas, para analizar la evolución del proceso eruptivo en curso. DIARIO EL HIERRO informará tras la reunión.”

    The Pevolca met this morning at 12:00 hours, to analyze the evolution of the current eruptive process. DAILY IRON report after the meeting.

    So we might hear some more soon.

      3. Can they tell us- can you ask?- what the temperature of the grey stains in Bob is? -see my post at 11-09 for why it would be good to know.

    2. A bit alarming to find the face of a candidate for the local elections on El Hierro as the first thing you see when you follow the above link.

      When are Pevolca going to meet? “Manana” is tomorrow isn’t it? – but my Spanish is extremely limited.

    1. Tried to find Los Gusmones on the map. Any ideas? Google pointed me towards northern Spain.

      1. It must be close to or within Las Puntas. My guess would be beneath the Golfo scarp close to Calle Guinea, but it is a guess…

        From Diario Hierro http://www.diarioelhierro.es/ this morning:

        “Un total de 11 viviendas de Las Puntas, en Frontera, han sido desalojadas de manera preventiva la noche de este viernes ante el riesgo de desprendimientos tras el terremoto de 4,4 grados de magnitud registrado en la isla y ante la posibilidad de que pudiera aumentar dicha magnitud, según las advertencias del Instituto Geográfico Nacional (IGN)”

        (Not translated because Giggle makes a mess of this)

    2. They have evacuated the town of Los Gusmones apparently, but Google Earth and Google Maps have never heard of it. Going by the latest cluster of earthquakes I guess that it must be North~ish of Frontera. Has anyone got a better location?

      1. I cannot find it either, possibly a translation/spelling mistake? I’ll keep digging through maps to see if I can find it. It’s got to be Frontera region, probably..

      1. Close to the cliff face and vulnerable to landslip. And also close to the tunnel entrance.

  48. Well, at that moment, I don´t know. But I can tell you that a few days ago, with the infrared camera, the red zone was (the only one in Hierro) was part of Altos del Julán and Tanganasoga Zone . tedElco

      3. When the Cabilde Perfidio Armas Shows up to beat you up, just start talking about having a Photographic Diving Competition, he will give you a medal instead 🙂

      4. Just so long as he does not give her a free ticket for a ride on the Ramon Margalef and an underwater camera.

      5. He seems to be full of energy and likes to show off, so he would just grab the camera and jump into the water himself, at least as long as there are press-photographers around.

      6. I will try find it. It can take some time with all the comments the last days. If somebody knows a quick way to search, please tell!

  50. A quick comparison of the locations of the EQs since 19/07/2011 and the locations of Bob and his brother when they first emerged:

    http://oi41.tinypic.com/4tszyf.jpg

    The earthquake locations taken from avcan.org’s cummulative image of earthquakes to EQ 11082 (http://www.avcan.org/?m=Animacion) and resized to overlay the image taken from Raymond Matabosch’s article in Earth Quake Report: http://earthquake-report.com/2011/11/04/guest-writer-raymond-mataboschs-own-reading-of-the-el-hierro-events/

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