Activity at El Hierro + Volcano of the Month

Valverde in El Hierro, close to the current activity. Image from Wikimedia Commons.

Valverde in El Hierro, close to the current activity. Image from Wikimedia Commons.

As time goes by we understand more and more about the activity under El Hierro. The Canarian Hotspot has several plumeheads reaching up under the volcanically active islands in the Island chain. It seems that for unknown reasons the activity has changed at depth so that El Hierro has become far more active than previously.

The island has been active previously, last time in 1947 when a merchant ship captain reported activity beyond where the eruption outside of La Restinga took place a couple of years ago. This eruption is though uncertain; the same goes for the 1793 eruption at Lomo Negro to the Northwest.

Plot from IGN showing the location of the earthquakes during the 3 last days.

Plot from IGN showing the location of the earthquakes during the 3 last days. Image from IGN.

There are no sources pointing towards the island having suffered anything even remotely close to what we are seeing now during historical times. As the activity has continued a pattern has started to emerge were magma pulses travel up via the plumehead and causes intrusions at depth under the island. So far every intrusion has occurred in different places under the island. Why the intrusions favor different locations is anyone’s guess really, it might though have to do with layering at depth causing the intrusions to occur in more brittle layers and that when they have filled up with hot material they stop being brittle and new magma goes somewhere else.

The pattern seems to be that an intrusion happen roughly every 90 or 180 days apart. They contain anything from a couple of hundred earthquakes up to a couple of thousand. The earthquakes form around what are most likely sill and dyke emplacements.

Explanation of the plot above: This is a view of the very recent quake swarm which began on March 14th. Update up to 16/03 7h14 AM. I have kept only the quakes of the present swarm and have supressed all the quakes prior to the 14th. For the first 2 views, the title bar shows count, datespan, date and hour of the events as well as magnitude. The color bar shows as usual, date on the left and terrain elevation on the right. The first view is a fixed view from the south, the second view is a fixed view from the east , both with an event by event animation. On each view there is a forward tilt of 10°. The following views are rotations with all events since the beginning of march, and views from the top and back. Data from IGN and NOAA, made on Gnu Octave 3.2.4 (Linux). Plot and explanation by DFM

The latest intrusion is to the northeastern side of the island, an area previously believed to be volcanically dead, which was the reason it was selected as the evacuation zone on the island. It is unlikely that an eruption will occur in this area even after this intrusion, the area was last active roughly two million years ago.

As I am writing this there has been 276 earthquakes and uplift seems to be delayed by two days before becoming visible on the GPS. Todays uplift at the HI00 station was 40mm and we can probably expect to see uplift to continue for 2 to 5 days more if the intrusion finishes today, otherwise it will continue for a while longer.

Conclusion

Explanation for the plot above: El Hierro 3D plot with the Gorbatikov microseismic inversion model. 2011 to 15 March 2014. Plot by Cryphia.

I do not at this time expect any eruption to follow this intrusion; it seems to be fairly small compared to what has happened previously. And even if an eruption occurs it will not be in the same area, instead the most likely spot is somewhere along the line from the Tanganasoga volcano to the previously erupting vent out in the ocean from La Restinga. There is also a smaller chance that Tanganasoga or Lomo Negro will erupt.

I would be highly surprised if this was the last intrusion we will see at El Hierro. And as the intrusions continue they will sooner or later start to happen in the same place and a true magma reservoir will start to form under the island. There might be a few small scale eruptions during this stage, but nothing major. As time goes by we will get to see how large the chamber will be, and if the previous intrusions are indicative it could in the end become pretty big. Remember that the average uplift is 7.5cm per year for the island as a whole.

So, expect years to decades of continued activity if the pattern holds true. El Hierro seems to be walking down the path from a fairly insignificant fissure eruption to the rebirth of a major central volcano. But, volcanoes are unpredictably so everything might just calm down without anything happening.

Another small danger of the activity is that the recurring intrusions will create increased mountain tension on the island and that a part will slide down. So far this does not seem likely, but one should not discount the risk of it happening. Thankfully the IGN has monitored the island for this for a long time so they should be able to stay on top of it.

Volcano of the Month

It is time to vote for volcano of the month for February. This time there was two nominated volcanoes that was active during February and they are Kelud and Nishinoshima.

CARL (text), CRYPHIA & DFM (plotting)

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248 thoughts on “Activity at El Hierro + Volcano of the Month

  1. And tomorrow there will be a really big treat for everyone as a post.
    It is a type of article that I have looked forward to present for a very long time and one that I am looking very much forward to read myself.
    I am sure everyone will be as pleased as I am. 🙂

  2. Ya want stupid ideas? Warning, sort of OT, but an interesting thought exercise.

    Based on a simple implementation of a milling formula (Von Rittinger), I get somewhere on the order of 25,000 kJ/kg to 100,000 kJ/kg of energy expenditure for Kelut’s eruption based on the grain size of Birgit’s microscopic photos as compared to the dome size. …But, I have no milling coefficient to apply to it, and am not even sure how to guesstimate it.

    This is based on the assumption that Birgit’s photos are of pulverized dome material and not fresh vesiculated magma. It also assumes the dome was effectively one large solid mass… before it blew up.

    In theory, you could apply that value to the estimated mass of the dome and get an idea of how much energy was released in pulverizing it. The rest of the energy would have gone into lofting the material skyward.

    On the extreme low end, (assuming the dome to be a simple sphere) I get 141,371,641.1 MJ used in the detonation of the dome. That’s in the Mag 6.2 range for the energy release on the low end ball park estimate. Doubling the dome volume yields a Mag 6.4 equivalent release.

    Caveat: A volcano is not a ball mill. The formulas are intended in calculating how much energy it takes to reduce the size of the source material to a specified size through a grinding/milling process. I used a 50 meter diameter dome as my starting size and 10 to 40 micrometers as the finished grain size. It’ actually an improper use of the formulas, but like I said, it was a thought exercise. Increasing the dome size to 500 meters does not change the outcome very much. The pulverized grain size has the greatest effect.

    • Additionally, this assumes that 100% of the source material was reduced to this size… which is untrue. Some of it came down in the form of gravel. The efficiency of that monster single step “grind” would go towards calculating the coeficient I mentioned earlier.

    • Nice approach on finding the energies involved. 🙂 I guess a mining company could calculate the electricity bill for crushing that dome up in specified sized particles 🙂

    • Nice one!
      For the rest, remember that here Lurking is calculating the energy release in the destruction of the lava-dome only. There are of course other energies involved. It is though a nice version of ballparking the energy-volumes that as a minimum must have been involved.

  3. http://grapevine.is/Home/ReadArticle/Bring-Your-Mobile-To-Hekla-In-Case-Of-Eruption.
    More confirmation that I am not the only person watching Hekla today.
    Interesting there is no ban on toddling over Hekla at the moment. But who in their right minds would risk it? Of course if it is an essential activity eg a scientific survey then I understand this. Going because you want to live dangerously or thrill seeking is selfish. If you get into difficulties then someone else has to put their life on the line.
    Nothing annoys me more than thoughtless people who, despite warnings and obvious danger still insist on getting a brief adrenaline rush or to take risks for personal glory. It happens here in the UK when people go to watch waves crashing on holiday resort sea fronts. They are warned to stay back but no! Some silly individual will always try to prove their “status” Possibly in a few minutes that status can change to ” No longer living”.
    Now we have mobile phones, the lure to take pictures , to be the first on You Tube with pictures of an event, the feeling of safety because of instant access to emergency services must be a factor in increasing the numbers of numpties who arrive to add to the work load of essential services.
    These Numpties or whatever you call them in your part of the world are an international problem. Unfortunately they will always exist. It would seem they have an extra gene that makes them willing to put their life at risk. This is biologically not a normal trait as it does not encourage survival strategies.
    Therefore they should not exist. Unfortunately they do. They come from all walks of life but I do think the ultimate Volcanic Numptie is this scientist.

    • You forget one thing about evolution.
      Yes, Numpties tend to die. But from a breeding standpoint the Numpties tend to impress young impressionable Ladies so on average the Numpties get to breed more than non-Numpties, thusly they spread their Numptie-genes thoroughly.

      I have written about it before… and now that we have gene-therapy we will just gene-modify the babies to get the traits we wish them to have and that will not be the same genes that would be best for us.
      With gene-therapy we could remove a lot of deceases and increase human intelligence.
      Instead we will get smaller, thinner women who are blond and blue eyed with huge frontal dampeners. We will also get huge-jawed, blond and blue-eyed men with strong back bones, large muscles and a gargantuan fence post in the forward position.
      To hell with brain and deceases…


      You may be right Carl…

      Screen grab from the movie “Idiocracy” by Mike Judge

    • I went on Hekla once. I think its risky to go hike on Hekla now, although I would probably do it again. I think we only live once, and eventually we die. So why refrain of doing something just because there is a risk of death. If we like it, and if you accept the life risk factor, then do it.

      A lot of activities risk our lifes anyways, where do we draw the line? Swimming in a tropical island can be deadly (sharks) for example. Travelling to far away countries can always involve its risks. Travelling to Jordan for example, or Syria, or Iraq.

      Still many people continue to hike Hekla. Icelanders are well aware of the risk. I think its only necessary that people are aware of the bigger risk and that this risk can be a deadly one. Then, if someone still wants to do it, because of a adrenaline rush, it is his/her decision. Why people cannot have the freedom to engage in life threatening activities?

      I think only tourists must be better inform of tthe current Hekla danger. If they still want to risk their lives, then it’s their call, their decision, their responsability. If nothing happens during their hike, good for them.

      Anyways I have a scheduled hike to Hekla this summer, I am not sure whether I go (besides the risk factor I have been already there so its not new for me), but so far they will probably go forward with this hike, again (last spring they did, even during if this was during the weeks after those earthquakes at Hekla last spring)

      • I tend to agree with Irpsits view here.
        We both make opposite choices in regards of Hekla. I would not go up Hekla, but I would go to Hekla if I had a fast car nearby and look up at Hekla from a nearby road.
        But, instead I do something that most far more people avoid doing and that in all likelihood is more dangerous. I go sailing alone in far away places, I have even crossed the Atlantic on my own.
        In both cases I make an informed choice. I know the risks are there, but in the case of sailing I trust my abilities and on the day they will not be enough I will still have gained more from sailing alone then I will ultimately loose.
        I think we are doing the opposite of being Numpties, we choose to informedly see what is out there that few get to see. Numpties tend to do things that make them land on fences groin first. Ie, the Numpties never ever make informed choices.

        In the end my biggest regret is that I live in a time where I can’t sail between the stars and explore things. And as things are going I do not think we will ever get to do that since we live in a new Dark Age.

    • “Going because you want to live dangerously or thrill seeking is selfish.”
      Yes it is a self-seeking pleasure, but likewise so many human activities are as well. What’s the problem with that?

      Moreover, no one is going to rescue anyone at Hekla, if that person is right at the moment when it erupts, there would be nearly no change for that person. So no rescue. That person will have its moment of adrenaline and joy, and then it might die (within a few seconds) or return back alive.

      • If one is on top of Hekla at the start of an eruption there would just not be anything left… :mrgreen:
        I think the big difference is if one bring back the experience for others to take part in. If one takes pictures and write about it the selfish part is removed.
        But, in the end, I think the biggest difference is if one does an informed choice or not. I have noticed that the informed ones tend to survive much more than the non-informed.

    • Evolution encourages brave individuals. Think about it, With the current world situation (modern age, sheltered from nature, abundant food, no need to hunt) it’s easy to be confortable.

      But back on the days when things were completely wild, and nature had its crazy climate changes, disasters, etc, it was the ones that were brave that could have more chances of surviving. Imagine a ice age is coming, those than went bold and venture on the northern lands, some of them they survived. Those braves ones were selected and they are our ancestors.

      Evolution encourages the Numpties. Not all of them survive, but some do, and find new niches.

      • Also if a global disaster would hit in the future, due to dramatic change, the people which would not be brave enough to venture new ways of surviving the crises, would probably perish. Nature throws these events once in a while, and encounrages diversity and many traits (inteliggence, team work, survival fitting abilities, etc). Nowadays there is little evolutionary pressure, but maybe one day we will be facing the evolutionary pressure once again.

        • You have a couple of really good points there.
          Half of the current population would die within weeks due to not being able to find a good survival-app.
          I think the survival rate would be far higher among those who are above 40 than below. The biggest problem there is that most of the breedable females are in the cathegory that would become extinct due to app-withdrawal. I guess that one of the most desired traits if one wishes to have a female to breed with would be to be able to create electricity so she could continue to App during the transition period.

          I guess I am suffering from blatant Ephebiphobia here :mrgreen:

          • Interesting responses. My definition of a numpty is someone who puts themselves into harms way without bothering to seek information or to.understand why authorities are giving advice. they are not making an informed choice. They also tend to be busy with their apps complete with earphones and expect traffic to stop for them as they wander across a busy road without a glance left or right.
            This is not to be confused with adventurous people. Who like the explorers and settlers weigh the pros and cons and attempt to create survival strategies should things go pear shaped. of course most of life activities are a gamble, some more than others but even gambles weigh the odds.
            Numpties don’t know what odds are and if they get into bother it’s never their fault!

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