Special report: Rift zone eruption continues at El Hierro volcano

This is going to be a short blog post about what is going on in El Hierro. But I have a longer blog post planned for tomorrow.

The current eruption in El Hierro volcano is a fissure eruption. As such a new eruption vent can be expected for the time while magma continues to be injected into El Hierro volcano from depth (28+ km). When a new fissure starts to open it is pre-seeded by a swarm of earthquakes. Lack of this knowledge, or some type of ignorance about this fact has me worried that a eruption. As there is a real risk of eruption happening close to a populated area in El Hierro. It is also a fact that a new fissure can open up extremely fast and with no warning at all. Since when the magma reaches the surface there is no guarantee that the fissure is going to open up with a swarm of earthquakes. In most cases that I know about, the eruption fissure opens up with no earthquakes at all and with no earthquakes. The only earthquakes that take place is when the magma is breaking a path up to the surface.

Earthquakes during the last 10 days in El Hierro volcano. The new magma injection appears clearly with earthquakes ion this map. Copyright of this picture belongs to Instituto Geográfico Nacional.

All earthquakes in El Hierro volcano since July. The new magma injection appears clearly on this map. Copyright of this picture belongs to Instituto Geográfico Nacional.

At this moment it is unclear if the new magma injection has got into contact with the magma that started to inject under El Hierro volcano in July 2011. If that happens the two magma injections are going to merge. But what happens after that is unknown to me. As I have never seen that type of process happen before.

When the El Hierro island is viewed from above it is clear that there are eruption periods where the El Hierro Island is covered with eruption cones in fissure eruptions. It is close to impossible to know if that this the case now or not. But I fear that it might be the case, as it has been long time since El Hierro erupted last time and the Island grows in fissure eruption jumps that take some time to pass over. One such eruption period jump appears to have started on 10 October, 2011. How long it is going to last depends on how large it is going to be. But this is going to last more then few weeks. But there are going to be breaks in between eruption episodes in El Hierro.

The harmonic tremor in El Hierro just before midnight of 28 October, 2011. The spikes are earthquakes N to NW of El Hierro Island. Copyright of this picture belongs to Instituto Geográfico Nacional.

There has been some drop in harmonic tremors from the first (and only?) eruption vent just outside the coast of El Hierro. This means that it might be closing up. But that is normal for this type of eruption. When this eruption vent closes up or just before it closes up. A new eruption vent is going to open up at new location. As the magma inside El Hierro volcano supports that in my opinion. When and where is the unknown factor in this equation.

As for the question on how long this eruption period could last. I am hoping that it is going to be over when I move to Canary Islands (maybe El Hierro Island) in about 4 to 10 years time (at the latest). But this type of eruption take a long time to finish. So covering this eruption(s) is going to be ongoing for some time now.

268 Replies to “Special report: Rift zone eruption continues at El Hierro volcano”

  1. Asistimos con estupor a la reapertura del túnel de Los Roquillos, que carece de estructura de refuerzo interna, o al repliegue de la Cruz Roja, mientras que en El Golfo no dejan de producirse sismos, cada vez de mayor magnitud, lo que podría afectar a la seguridad del túnel. Recordamos que desde el comité científico se dijo que no sabían que podía estar ocurriendo: “no lo sabemos”, ya que el GPS HI04 estaba fuera de uso por fallo de la WiFi. Ahora, en la nueva nota del Gobierno de Canarias del día de hoy, se dice que la deformación permanece estable en el norte de la isla, pero no aclaran si HI04 funciona correctamente. Tampoco despejan la duda de a qué se debe la nueva sismicidad en El Golfo: si a reasentamiento o a una nueva posible inyección de magma. Es necesario recordar que, según el propio comité científico, dicha duda venía provocada por el mal funcionamiento de la estación HI04. ¿Se ha reparado? ¿Se ha sustituido la WiFi por la de otra estación, HI01, por ejemplo? No lo sabemos, pero en la página oficial del IGN HI04 sigue sin aportar datos. Lo que hasta ahora ha sido una actuación adecuada de científicos y autoridades se está tornando desafortunada. La población de El Hierro se merece un mínimo de respeto. Desde AVCAN solicitamos al Gobierno de Canarias y al comité científico una respuesta acorde con la situación actual. Transparencia y datos (AVCAN)
    We assist with the reopening of shock tunnels Roquille, which lacks internal reinforcement structure, or the withdrawal of the Red Cross, while in the Gulf do not stop earthquakes occur each time of greater magnitude, which could affect safety of the tunnel. We recall that from the scientific committee said it knew it could be happening: “I do not know”, as the GPS M I04 was out of use WiFi failure. Now, the new note of the Canary Islands Government today said that the deformation is stable in the north of the island, but not clear HI04 working properly. Nor clear the doubt as to what should be the new seismicity in the Gulf: if possible relocation or a new injection of magma. We must remember that, according to its own scientific committee, that doubt had been caused by the malfunction of HI04 station. Have you noticed? Has WiFi replaced by another station, HI01, for example? We do not know, but the official IGN still provide data HI04. What so far has been adequate action by scientists and authorities is becoming unfortunate. The population of El Hierro at least deserves respect. From AVCAN ask the Canary Islands Government and the scientific committee a response commensurate with the current situation. Transparency and data (AVCAN)

    …..And still the politicians seem to be showing no respect for the intelligence of the people for whom they are responsible.
    From the translation I am not clear as to whether the red Cross are being withdrawn from the whole Island or what exactly is happening about the tunnel.
    It seems HI04 has been lost by many but still functioning for IGN…
    In all a confusion reigns…

    1. For what I ‘ve read, they have only disassembled the premises in the football club. But Red Cross is still there.
      Last EQ
      29/10/2011 22:32:34 27.7604 -18.0585 21 2.1 4 W FRONTERA.IHI

    2. First of all, Spanish politicians NEVER show respect for their own citizens, and least of all for intelligent people. The sad but true reality of a country that we can see go to tatters by speculation, corruption and politics.

      HI04 is without wifi, so no data so no idea of if there is ground deformation.
      The tunnel has been opened, without the promised reinforcements in the tunnel. The ‘repliegue’ of the red Cross, that is translated as ‘withdrawn’ can also mean ‘someone who retreats in oneself’, or ‘fold various times’… Maybe Renato has an idea how to understand “repliegue” here?

      The scientific committee said they don’t know what will happen.

      Hang on, will put a translation of the full text below…

      1. Xana:
        The translation has already been placed by Diana Barnes (see above).
        And I placed my own interpretation of Red Cross “repliegue”. Yes, “withdrawn”, but in the context, they were talking about the soccer building where people were being sheltered, which was arranged by Red Cross. Since the shelter was disabled, Red Cross has withdrawn from the site. But one reader said that Red Cross would quickly get another shelter ready to receive evacuees, if it becomes necessary. So, I understand this was only a “localized withdrawal”. 🙂

      2. This is reassuring. Thank you Renato.
        Although I am miles away and have no friends or relatives there I still feel concern for our friends on El Hierro.

    3. In shock we witness the reopening of the tunnel of Los Roquillos that lacks the reinforced structure inside, and the withdrawal of the red Cross, while in El Golfo the seismic events don’t stop happening, and these are ever with greater magnitude, which can affect the security of the tunnel. We remind that the scientific committee said that they don’t know what is happening right now: “We Dunno”, given that GPS HI04 was out of order because of a WiFi-failure. Now, in the new statement of the Gobierno de Canarias from today, they say that the deformation remains stable in the north of the island, but they do not make clear id HI04 functions correctly. Neither do they take away the doubt that given the new seismicity El Golfo: if there is a displacement or a new possible injection of magma. It’s necessary to remind that, according to this very scientific committee, the above mentioned doubt was provoked by the malfunctioning of station HI04. Has it been repaired? Has the WiFi been substituted from that of the other station, HI01, for example ? We don’t know this, but on the official page of the IGN HI04 continues without showing data. That which has been the adequate acting of scientists and authorities up till today, is turning for into something unfortunate. The population of El Hierro deserves a minimum of respect. From AVCAN we ask the Gobierno de Canarias and the scientific committee an answer that responds to the actual situation . Transparency and data (AVCAN)

    1. Please note that you are posting links to your google email account. I am going to edit the address out. As this can be dangerous to your email account.

    2. You know you’re linking onto the Google mail system. I get the Google log on screen if I follow the link.

    1. Well… I am now thoroughly creeped out.

      Initially, I saw what appeared to be a nice 6 inch concrete liner on the tunnel at the entrance. That didn’t last long.

      The rest of the tunnel is rough-hewn and raw rock. It’s dark, and probably a result of vehicle exhaust and basaltic rock/tephra.

      I can see why they closed it.

      BTW, the site http://www.cicar.com throws broken links on their page. That site was emblazoned on the windshield of the car.

      1. I think that an earthquake with a magnitud 1.0 would be enough to make it disappear…Please, excuse this joke in this situation. I am really worry for my people.

      2. Nothing wrong with a bare rock tunnel… my dad worked for the hydro electric in Scotland, and I’ve been in many bare rock tunnels there, both for water and for access to underground power stations. Concrete lining is usually only needed in hard metamorphic or igneous rocks near the portal, where the rock is less stable, or to control water ingress – otherwise they’re self-supporting. Do you really think a few inches of concrete makes any difference to the thousands of tons of pressure from the overburden of a thick layer of rock?

      3. Bare rock tunnels for access through granite or stronger sedimentary rocks for short distances are somewhat different than longer tunnels through more recent volcanic deposits.
        Tunnels are self supporting ….to an extent but Scotland has few earthquakes over M3 they do have more than the average for the UK.
        There are, I am sure, some safety installations that strengthen and supply more support are used in tunnels such as the Channel tunnel and the Simplon etc…..both of which are earthquake Zones. We need GeoLoco here for the expertise on this one.

        My tunnel engineering knowledge is pretty non -existant so for now I will go with the local experts…However as a layperson knowing that the eruption is not over I would be very concerned.
        I suppose before the tunnel was built there was/is a steep road that could be used instead.

  2. OT : OT : OT

    I ate supper a few minutes ago… the wife had some game show on TV. They were cutting to commercial break. All of a sudden I hear what sounds like someone poking a cat with a fork.

    ??? I ask the wife, “That the @#$ was that?” She says it’s a Halloween sound effect, they have been using them all week.

    Now… I’ve been around a while, I don’t recall poking a cat with a fork to be representative of Halloween. Does anybody else know of this practice? It’s new to me.

    Meanwile, a blast from the past, when the Dot.com bubble was going strong and the commercials were getting… “creative”.

    Cat Herding.


    1. Poor animals!
      When I was a kid, my older cousins used to do such atrocities to the cats. And for no witchcraft or Halloween ritual purposes whatsoever.
      Plain, wicked, human behaviour.

      1. “my older cousins used to do such atrocities to the cats”

        Herd them or poke them with forks?

      2. Alsa we now have Halloween as a huge commercial “THING”. The old English customs and the actual meaning of All Saints, holy people’s, day has been forgotten.
        It would be good though if I could arrange a nice sensed M3 quake for midnight or when the Local Hooligans come knocking on my door! 🙂

  3. I have tried to replicate Son De Bueu’s schematic to Lurking’s plot of EQ latitude vs depth.

    Link: http://oi43.tinypic.com/23ifrww.jpg

    It’s interesting. Black lines (wobbly – sorry, I am not brilliant at free hand drawing with a mouse) represent Son’s proposal. Red arc is another one.

  4. Here is the one I saw:
    29/10/2011 22:52:56 27.7948 -18.0470 20 km 2.7 4 NW FRONTERA.IHI

  5. All quakes between 20 and 15km depth so far today. It will be interesting to see if this is a shift to shallower quakes.

  6. Well… here is an answer to a question that I have had for a while. Some of you have had the same question, and I provided a plot that was kludged together to give at least half a guess.

    The question was what is the pressure gradient where these quakes are located? In other words, what is the vertical load on the rock that is fracturing?

    This value, is known as lithostatic stress, is the force of all of the mass above the area in question. When you get down into the nuts and bolts of how a quake occurs, this is an important part of the forces that have to be considered. It’s also known as the confining pressure.

    The temperature and the pressure that a material is under, determines when and if it will melt. I don’t have the temperature part of the problem, but through some pivot table juggling skills that you all have allowed me to learn, I was able to fabricate cells in one of the quake spreadsheets that allow me to calculate the confining pressure for each individual quake.

    A real big “woot” on my part.

    Here is what goes into it. Above each quake, is a mass of crust and or water. In calculating stress, the usual value that is used is 2700 kg/m³. This also happens to be the average density of granite. Basalt isn’t that far away, ranging from 1954kg/m³ to 3011 kg/m³ depending on whether it’s broken or solid. Gabbro ranges from 2700 – 3300 kg/m³. In any case, 2700 kg/m³ is what I usually see used in the calculations in many papers and probably serves as an “industry” standard. It’s also what I used in the calculations.

    Water, specifically sea water, has a surface density of 1030 kg/m³. At deep parts of the ocean, it can get as high as 1050 kg/m³. I split the difference and went with 1040 kg/m³.

    The calculation takes the depth of the quake, and either adds or subtracts the level above or below water. The are under water has the mass of the overlying water added to the mass of the overlying crust. Those quakes with no water use pure crust to the surface.

    This is about as accurate as I can get.

    Anyway, here is a profile view looking east of the quakes to date… color coded by confining pressure at that point.


  7. Lurking

    Thank you for your graph please would you explain in basic terms what the graph means to someone like me who looks at the graph but sorry does not understand (although would love to ) what this means.

    1. The plot doesn’t really show much other that one aspect of the quake ddynamics that you don’t usually see. Quite a few things go into a quake that lead to rock failure. This is one of those things. Essentially, the shear stress has to overcome the rock strength as it exists under that compressive load.

      This compressive load also changes the melt temperature and the dynamics of the rock itself.

      The pressures are in megapascal.

      1. Lurking:
        It’s getting more and more interesting.
        How come the quakes in lighter blue be under less pressure than those in darker blue? Does it mean that they get an extra bit of pressure from expansion? Or am I way far from understanding what you mean?
        And how about the really deep ones, in orange and red? Aren’t they supposed to be under a higher pressure?
        What does this plot say to you?

      2. Its not that it says anything specific. Stress and strain are two of the components that make a quake (along with failure point for the material and the environment)

        This is just a plot of one of those components for the indicated quake.

        One way to look at is that the less compressive stress, the less energy needed to crack the rock and make a quake. Compressive stress tends to hold the rock together… up to the point that it deforms or cracks under other forces.

      3. Nice plot – I don’t know if you have records (or an estimate) of the pre El Golfo terrain – it might be interesting to look at the difference in confining pressures in the various areas – pre and post el golfo formation. To see if the isostatic movement suggested by Peter is borne out by the data.

  8. oops 3.9 just now

    ML 3.9
    Date time 2011-10-30 07:46:35.8 UTC
    Location 27.79 N ; 18.04 W
    Depth 22 km

    1. Jón , avcan say the increases in the tremor are due to magma explosions making his way, are you agree with that assessment? Thanks for your time.

    1. To my simple eyes this isn’t looking good. 3 quakes of 3 or over in the spaceof an hour must surely be worrying. most particularly as one was almost a 4M.
      I wish I didn’t have to go out this morning!

  9. Jón, quakes are increasing in both intensity and frequency.
    According to Peter Cobbold we should see more shallower quakes.
    Do you have any clues for what is going on with this growing swarm?

    1. I mean: According to Peter Cobbold we should see more shallower quakes before an eruption, and that seems to be Carracedo and many volcanologists opinion. Do you believe we could have another opening vent in El Golfo area?

      1. But Jon has said (and please correct me if I am wrong) that fissures can open or close without warning.

        It has been proposed that this is rifing; and, the eruption off La Restinga is a fissure eruption.

      1. Visually, there is no “jump”. Just an increase in amplitudes, if that’s what you mean.

  10. I think we all believe that these quakes will set in motion a number of new important events. What i do fear is that a powerful shock of approx. M 5 might trigger serious landslides on the steeper south coast. A 5 will have at least a MMI IV to V shaking in a 5 to 10 km radius. Luckily that area is not populated.
    Just written an update about that + an advise to my readers to follow the discussions in this panel.
    They will now about a possible new event much faster than anybody else in the world in this Jonfr panel

    We are still looking for a volunteer wanting to write about volcanoes in the ER site. We have a hard time in following it up when there are strong earthquakes like last week.

      1. Yes certainly, but i guess that authorities will close the tunnel again when the first + M 4.5 shock will occur. We can only guess of course, but you maybe sure that they are wiggling on their seats at the moment. Very difficult to take a decision pressured by people who only look at their comfort and science who sees the danger coming near.

      2. The picture is from the S entrance of the Los Rochillas tunnel (=Tulel del Golfo) north of Frontera, on the NW coast.
        Google Earth: 27°47’54.32″N 17°59’11.07″W
        The village is Las Puntas. The possibility of a slide that Armand mentioned is on the south side of the island. This area is not populated (too steep, I think).

      3. There is the road across the mountain, (el cumbre) that u cannot see in this pic. As well as that is the road going around from the other end of the valley, from Las Salinas to La Dehesa and around that way to El Pinar/Valverde. As i understand though, this is the area where most of the tremors are accumulated though (also at close approximity to the el cumbre road, therefore, if an eruption is due in that area, then the tunnel would be the only way out. OR, by sea.

  11. Armand

    I live on one of the canary islands do you just want someone to type for you I am english so not very good typing spanish.

    1. No, that’s OK , but thanks for letting me know.
      It is more in general (worldwide) to aid in following volcanoes. We need an almost daily scanning of some press sources in order to be a little updated.

  12. If I read Carracedo right, he said a ball of magma was just below the 14km crust/mantle boundary. That is still a very long way for it to break through with any speed. He also referred to 250 magma sites already under the island.

    I still wish they were offering transport to another island those who would like to leave.

    1. Alyson
      A comparison with the evacaution of Heimaey might be useful. Its a tiny island and the harbour was only about2km from the fissure erutption site – and they all got off. And they had no seismometer network to warn them.
      On Hierro the Valverde area would be a refuge., although the western tip might be more use to Sabinosa .The challenge the authorities have is to predict how soon to ask people to move and by which routes. A trend upward in the EQs might be one signal they would use to foretell an eruption. But predicting a big EQ and possible landslip- I dont know how of if they can do that.

      1. Is there a port on the western tip large enough and isn’t the sea stained off the west ridge?

        Don’t forget that Valverde has also shown some displacement, albeit less than Frontera and Sabinosa.

  13. It feels as if the inhabitants of El Hierro are acting as the frogs in slowly warming water. In the end they will die from overheating. If the frogs jump in hot water they will jump out in a split second. The volcano is taking his (or her?) time and that makes people lazy for acting. I think that if the quakes that we saw today were the first ones everybody would flee… and personaly i think that is what they still should do. Offcourse i understand that being evacuated from home for something that is perhaps not going to happen is very difficult… but what if it does… will there be enough time? I’m not confinced…
    What do you (reader) think about this?

    1. Well, maybe basic human nature and resistance to change has got something to do with it? There’s quakes on the west coast of the States all the time, and science has confirmed as fact that it is all just going to collapse into the sea one day when the -big one comes..I don’t see them evacuating in a rush either, although facts stare them in the face. Who will tell what day the BIG ONE comes? So, it would be safest for the whole of the west coast as well to just leave NOW.

  14. Well, I was apparently moderated off a few days ago for saying mostly what everyone else is now saying. Historical accounts of volcanic eruptions show that people stand around and watch and wait instead of fleeing. Why wait until someone from government tells you? If I lived in Frontera, I would go through the tunnel now and show up somewhere else. And everywhere on the island, I would have a face mask with me at all times.

    There is a small desktop translator called Musonya Translator which uses Google for the translator. It works well and sits around easy to bring up. It can translate small little paragraphs quickly and is useful for quick translations while browsing. It has the Icelandic language listed, but I find that it doesn’t seem to work for that (must be Google.) It may be of interest to someone. It is free. I am not associated with it, use your own judgement. It passed my detectors okay.

    Thank you all for your interesting and informative discussion.

  15. Events really happening now. Loads of quakes – 2 x 3.9 in last 12 hours, harmonic tremor increasing. Things must be happening – hope islanders are OK.

  16. Southern town was evacuated tonight. It seems that in the late hours of evening some explossions took place in the subacuatic volcano, and the could’t see more but the new island may be emerging from the water right now. In a few hours we will see with the sun of light! Too much emotion today!

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