Watching Hekla

Kobba informed us that the alert level at Hekla was raised to yellow:
http://www.dv.is/frettir/2013/3/26/ovissustig-vegna-jardhraeringa-i-heklu/
Some things are up with Hekla….Alert levels raised to yellow due to “peculiar unrest” in Hekla”

“Translated: National Commissioner of Police and the Commissioner of Hvolsvöllur declare confidence level of civil eruptions of Hekla

The Icelandic Meteorological Office has informed the National Commissioner for Civil unusual Seismicity at Hekla. IMO has also increased monitoring points Hekla to yellow due to air traffic, which means that the volcano show unusual activity.

Uncertainty level civil means for increased monitoring of the actions of that at a later stage could lead to health and human safety, environmental or building will be threatened. To describe the level of uncertainty is part of the processes in the organization of civil protection to ensure formal communication and information. Uncertainty level is declared to inform the appropriate emergency and is a process in civil emergency planning and the lowest of the three.

In light of this, will the National Police Commissioner and the Commissioner of Hvolsvöllur warn people on journeys while Hekla uncertainty level is valid.”

http://www.ruv.is/hekla Image taken on March 18th.

Erik Klemetti has the news too on his blog Eruptions. Alert Status Raised at Iceland’s Hekla

Icelanders photo as the staff

Icelanders photo

Icelander: “VC staff photographer has sent us this test image. Expect more of it in action, whenever that will be. Enjoy. http://i50.tinypic.com/2e5v5ax.jpg

Yes, these were for express use of VC and be used when Hekla became “imminent” :-) Copyright lies with the photographer. Here is another angle from October last year.
http://i49.tinypic.com/1z9jsw.jpg ”

Here are plots by chryphia of Hekla´s local earthquakes from 2000 until today.

Hekla seismicity 2000 to 2013. View from NE. The bulk of blue events occured on the day of the last eruption Feb 26, 2000.

Hekla seismicity 2000 to 2013

The last two earthquakes from the listi were on Mar 21st and 23rd and were located in the small group at 10 km depth:

Hekla seismicity 2000 to 2013

Hekla seismicity 2000 to 2013, view facing West. The depth axis is compressed about 2x in order to get the Moho layer (http://www.seismo.helsinki.fi/mohomap/) into view. The topology is from geodas-design-a-grid.


Icelanders image and his explanations: Quote: “for these watching IMO uncorrected strain charts – this is how they appeared in April 2012, the month I thought it whould go off, so nearly 12 months old.
Notice the large drops at HEK (other stations were not operating then). Graph is stretched or schrunk, to get “same unit scale” (a feature or the Original IMO charts I do not like, is that their scale is NOT constant, but fortunately they are scaled, so here goes). http://i45.tinypic.com/ziopkw.jpg
Yess, top graph is BUR, same days as HEK (lower). I have the days before these too. Including a big quake of international standards, first a meeting, then more plots (Yes these are mine “Scale-ings”!)”

Remember Carl wrote a lot of posts on Hekla, you can find them here.
Spica

525 thoughts on “Watching Hekla

  1. IMO Specialist remark – http://en.vedur.is/#tab=skjalftar
    “No seismicity has been detected northeast of Hekla since the weekend. One small earthquake occured 8km south of Hekla last night, which is no unusual spot for seismicity. The aviation colour-code for Hekla is still ‘yellow’. The uncertainty level declared by the Icelandic Civil Defence is still valid. No obvious signs of an imminent eruption are detected.”

    • this is normal, only when it goes in 10,000 or more it gets interesting. This graph is useless untill anything major happens, and its designed to catch major changes

      • The episode seems to have started just when I went to work, and started subsiding again when I came back home. Maybe I should just sit home and keep watch for Hierro, then local population would stay safe 😀

    • Yes some largish quakes there. El Hierro is determined to make a comeback after a period of relative quiet. There have been rather a lot of +3 quakes in the last couple of hours.

      • OT, just wanted to say thanks Lurk for your responses to my questions the other day. (Sorry for the tardy responses on my part … if you knew what was going on in my private life at the moment.. you’d be happy to drive the interstate for the rest of your life!)
        Be that as it may, one day I want to get up to speed on the mathematical analysis as the last maths I did was over 30 years ago at high school. But my lack of familiarity with it is preventing me from taking the discussion further, which is really frustrating.

      • Depends on the sort of ground you are standing on. They will eg. be felt much more on sediments than on solid rock.

        And as for the seriousnes re. an possible eruption, the same and depends also on the plumbing system and the volatility content of the magma involved. (no expert)

    • Hmmm, that looks a relatively small rockfall but Avcan have said, “reports of major rockfalls”. Lets hope they aren’t bigger than the one in that photograph. Can see from the scree slope on the bottom it is a relatively unstable area but those houses look to close for comfort! I wouldn’t want to be living there at the moment.

      • I think this photo is from their archives not a recent one…but I might have misunderstood a comment from them…bing translation is not the most reliable source….

      • The waves of the Atlantic can have an influence on the background noise, but not on these big bangs there.

        And what do you mean by Montenegro? It is in another part of the world (eastern side of the Adria /Mediterrenean).

        • Or did I misunderstand that now? Did you talk about quakes out in the Atlantic resp. in Montenegro? (Can’t see any such though.) And I don’t think they would influence what is going on there.

  2. Drat now IGN site unavailable for a while, those reports of rockfalls have triggered a surge of people linking to it I expect.

    • That is not good at all. Sounds like those rockfalls could be MAJOR after all as that sort of magnitude would be trouble even if it was out at sea.

        • If you are standing on the ground…. you are feeling an acceleration of one “g” pulling you towards the ground. If you are on a roller coaster and you go around a corner, your momentum will cause you to feel some measure of acceleration towards the side of the cart. In other words, the “down” that you feel pulling on you is a combination of Earths gravity, and the effect of your momentum. The combination of all of these forces determine what direction is “down” that you feel.

          When a structure (or a rock) feels a g acceleration from a quake, it is generally about transverse to “down”… or somewhere along the horizontal plane.

          You feel the same type of acceleration when you accelerate or brake in your car. The force pushes you back in the seat or towards the dashboard.

          For a quake, this is what shakes the rocks loose. The larger the value, the greater the shaking.

          As for peak velocity, that is simply the maximum speed that the ground appears to move at relative to the stuff sitting on it. Again, bigger is worse shaking.

          • Thanks so much. I can understand that now. Sadly i had to leave school at 15 for financial reasons, such a waste as i loved learning.

        • at the moment this seems the last major EQ. Since then it is cooling down a bit. We get the information ~30 min after it happens and on the seismograms nothing that strong is currently .ongoing, but that could change again.

        • Lets hope no more over a 4 as I agree, even 1 isn’t good by two so soon together is worrying.
          Now I must go and walk my restless little dog. I will look when i get back if there is any more news of those rockfalls as that is worrying me now. When will they show more concern for these poor people?

  3. just got a chilling thought, is “the rubber band” stretching ?? since this graph was put up, this steady down trend is rather unusual, as is the linear decent as is happening now at HEK.
    The Hekla alert can be regarded appropriate cover for any other largish coming from the area´s east of Hekla and across the rubber towards Laki. http://hraun.vedur.is/ja/strain/1sec/index.html

  4. AVCAN: “Terrremoto de 4.6 en el Hierro, sentido en la Palma, La Gomera, y puede que Tenerife y Gran Canaria.. y parece que alguno mas por encima de 4.0 casi nada (Enrique)” – the locations where the earthquakes were felt!

  5. I thought things were starting to quiet down so I took the opportunity to run to the store. Boy, was I wrong!

    • and Iceland is like christmas coming soon again, I got this feeling anyting can and proably will happen , two places in the Atlantic , question who be first 🙂

      • Well, if Katla suddenly could join in and beat the other two volcanos Carl would have to dance naked in front of the camera – that should bring him back……

        • Katla has been quiet, but noting of large has been happening anyway.
          The “expected” 6 R in the North did not happen, so it could be Grimsvötn or any other mountain to beat Hekla, even Eyjo is not dead. However, these Hekla quakes were “unusual” compared to the short time I have watching the IMO quakes (since 2004)

  6. 10km and a 4,4 it is – debt pretty close to what Carl was worried about earlier. Way out in the ocean though….

    • Good grief – the volume of material in the original landslide that created that cliff doesn’t bear thinking about ….

    • Metadata of the same image posted elsewhere had a date of 31 Dec 2009 so I don’t think this is current.

  7. This with thanks from Earthquake Report. As Ever Armand is doing a sterling job with updates. Thank you Armand and all at VR.
    ” Spectacular earthquakes going on right now in the ocean to the west of El Hierro – A new strong earthquake (preliminary Magnitude 4.4) made chairs and ceiling lights moving and windows trembling. This last earthquake was also felt at the other islands.
    Based on our earthquake experience, we expect that an M5 will be the absolute max. for volcanic earthquakes. In rare cases the Magnitude goes even higher but these are mostly volcanic explosions which nobody expect to happen + the shaking of every current earthquake is weakened by the sea.
    We would advise people at El Hierro, to stay away from steep cliffs as rockfall can happen at any moment.”
    http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/

  8. And another larger quake at El Hierro, a 4.4 this time.
    1201326 27/03/2013 16:10:55 27.7792 -18.2906 11 Sentido 4.4 mbLg W FRONTERA.IHI

          • Hope it all dies down before their bedtime! Although in many places on that island I would be out of their and headed fot the North of the Island, Even if I had to sleep in a tent.

        • There’s this, but still 10mins too early
          1201351 27/03/2013 17:16:02 27.7476 -18.2520 16 3.7 mbLg W FRONTERA.IHI

          • I think it could be this one, a 3.8
            1201387 27/03/2013 17:23:48 27.7367 -18.2534 22 3.8 mbLg W FRONTERA.IHI

          • It seems to be a 3.8 at 17.22 at 22Km.. There’s been anoher one since at around 17:55. They’re having a real shake up today.

        • No worries Newby. It’s all happening thick and fast! For those who want to know what an upward GPS trend looks like …they don’t get any better than this! http://www.01.ign.es/ign/resources/volcanologia/jpg/hierro1SVVRTRF_neu.png
          I am presuming the tough sedimentary layer extends westwards from El Hierro and the 11 km. depth is where the magma is trying and maybe about to shove through so allowing the magma to flow freely out through the top layers of rock and onto the seabed. Please tell me if I am wrong in this concept

          • Yes Diana, I think there’s a line of thought that when magma hits the Jurassic sediments they will go through relatively rapidly. Not sure how thick they are above the present swarm. Stroncik and others suggest ascent is rapid, but dont invoke that layer in their mechanism.

          • Ps .. not meaning to imply you were gone, just haven’t seen you for a day or two.. (this internet thingy can be fraught with miscommunication)

          • Hi Peter (thanks for the link to the Magnetic Survey paper tother night) and Diana, .
            The idea that magma will break through sediment relatively quickly does make sense, but as Karenz says, we are not at that “limit” yet.
            I think the emergence of BoB backs up the theory…

          • Hi Bruce,Schteve,
            I’ve been lurking, and spending two days on and off trying to get access to eq-report and to get this site out of some sort of ‘economy’ mode. But I now think its the isp at fault as I’ve been through all the firewalls etc,etc.

            I think Gorbatikov’s western stack is the magma conduit and when the swarms have exhausted all lateral routes to escape it will start upwards, or stall. But its odd that the microseismic survey showed no horizontal layering.

            This swarm kills off my idea of tectonic causes.

          • Because of its western extent? To be fair, this is the first time it has gone in that direction so your theory certainly had some credence, but yeah, this pronounced westerly direction is kind of hard to shoehorn into the frictional theory you posited, unless of course the magma genesis is deeper in your model and this sill-forming activity is just a product of rising melt looking for the path of least resistance.

            Note how there is a pronounced dead zone over Gorbatikov’s low velocity zone and matches pretty closely with the “hole” that Geolurking identified at the very onset of activity. It is still there and I imagine the system is now pretty well primed. This swarm may lead to nothing, but where will the next one go? There aren’t too many places left but upwards.

  9. Now, the way these quakes are moving towards the island, could this mean a rift is forming or something?

  10. Not volcanic nature but… 3.3 22km SSW of La Quinta, California 2013-03-27 18:17:43 33.493°N 116.439°W 9.0
    3.7 22km ESE of Anza, California 2013-03-27 18:17:00 33.490°N 116.447°W 3.9
    3.4 22km SSW of La Quinta, California 2013-03-27 17:50:29 33.491°N 116.446°W 4.5

    http://www.usgs.gov

  11. 2013-03-27 18:36:29.8 52min ago 67.06 N 21.11 E 1 1.8 SWEDEN
    And that was Carl falling off his seat when checking our chat on Hekla and El Hierro.
    (((Sorry could not resist.)))

  12. Non intelligent question from an old man. Back when Bob was really acitve “the graf” would be “thick” (sorry for the lack of a better word). Now “the graf” is very thin inbetween the quakes. Is there really that much going on at Hierro, or are the quakes to deep for “the graf” to be real thick and healthy?
    http://www.ign.es/ign/head/volcaSenalesAnterioresDia.do?nombreFichero=CHIE_2013-03-27&ver=s&estacion=CHIE&Anio=2013&Mes=03&Dia=27&tipo=2

    • probably downscaling…if I understand the question well. Even the “minor” EQs are hardly showing up any more. BTW 19.57 another biggie..

      • Well, they downcaled time after time back in 2011, but “the main graf” was still thick. For those of you that understand this far better than me “the experts” ment that flowing magma caused this “thick graf”. Am I “totally in the darkness” asking this?

      • Inge B – thats what I asked about. Get a clearer picture now. So for the “mean show to start” we need more harmonic tremor then…

      • If you want a second non-expert opinion, I’d say Inge is spot on. HT is primarily caused by the “sound” of bubbles forming, moving and popping in lava as it moves towards the surface and erupts (there’s also the theory of magma “wagging” – magma bouncing back and forth as it moves up the conduit) coupled with degassing and hydrothermal signals associated with an eruption. We haven’t seen any of that yet in this episode. If you think we are excited now, just wait until the first long-period signals occur, then you’ll see us getting really excited. 😆 Bob started with HT, slowly at first but not stopping for one second and slowly growing in strength. As far as I know, no one has managed to exactly correlate the onset of HT and the actual beginning of the eruption. It would be interesting to know how long the time lag was (if any).

  13. Hi
    I’m doing the update plot for today and I noticed that quite a lot of the new “strong” events appear to be on the outside of the main cluster.

    schteve edit x

      • Good evening all, greetings from Tenerife..I have just been watching local Canarian news, and the mayor of La Frontera was on the phone, telling us that the rocks that fell were in an area where it is quite usual for rocks to fall when there is bad weather, rain wind etc, so quite normal that the earthquakes affected this area…and said some of the residents in that area thought they felt the earthquake, when in fact it was the force of the rocks falling that shook the ground! They also showed footage of dead fish floating in the sea….not loads but quite a few….they have just annonced that that a yellow alert is in place in the West of the Island nearest to the epicentre, but the rest of the Island remains on Green…the residents of La Frontera that were interviewed said that the earthquakes felt today made them feel a little uncomfortable, but the general feeling seems to be one of calm at the moment…

        • Hi Debbie! Good to have some news from someone nearby! I seem to remember that we first heard of Bob through stories of dead fish. Did you feel any of the larger tremors? One of the news sources said they were felt on all the islands. I know you have to be more or less stationery to feel smaller tremors so you may not have felt anything. 🙂

          • Hi Talla, no I did not feel anything at all over here, I did wonder about the dead fish and to honest I missed the very first part of the reporting, but everything else they were reporting seemed to be very current, so cannot see why they would put old footage on…I suppose that only time will tell …

  14. What an eventful day. I am not sure where to look next. Askja , Bardabunga, Hamarinn, Hekla in Iceland. I just wonder if a fissure eruption is brewing somewhere along the Dead zone down to the east of Hekla. I am most probably reading far too much into normal quakes but what a change from the last Month or so. It’s been so quiet.
    El Hierro is again rocking. Those poor islanders. It’s interesting looking at the contour lines around the South and West of the Island. They are of a similar degree of slope and irregular in shape. The steep seamounts to the North west of the area are possibly small volcanic mounts. The Canary Hotspot must be at it’s most active here. Also notice, where the material from the great landslides presumeably came to res to the North especially there are no seamounts. They have either been covered or flattened my the huge rock slides. However in the south there are small seamounts appearing through the landslide debris. I wonder if these are newer eruptions,rather like Bob. Hence it is possible that these are an indication of the most likely eruptions taking place.
    I am really just ruminating here. But it does seem like the lines of least resistance are towards the south West of the island..

    • I guess this sounds pretty perverse in the circumstances, but I’d love to experience the feeling of being on an island that started heaving and snorting like a dragon coming to life. It’s not often you get to experience the earth as a living creature.

      • I experienced three stronger earthquakes up to know. Very strange feeling. The first one I found so disconcerting that it gave me nightmares even (was just a child then).

        • I’ve been in a couple of large ones (albeit not very damaging). And I have visited a couple of locations post large damaging earthquakes. You don’t forget them, especially if you aren’t used to being in an earthquake zone.

        • Earthquakes scare me much much more than volcanoes.
          1) you don’t get any warning. They just sneak up and grab you.
          2) the energy release is often much greater than in an eruption and that energy is all devoted to making the ground shake whereas most of the volcanic energy gets vented upwards into the atmosphere
          3) with appropriate warning and preparations you can get out of the way of an eruption, even a big one but you can’t really do that with an earthquake.
          4) the affected area of catastropic damage is arguably greater for earthquakes.

        • 3.2 is my max. My recollection is the entire building lurching to one side and then swaying to a stop. Spatially, what went through my head were all of the framing and joists wobbling back and forth. At least that is what I imagined in order to fit the perception as it happened.

          I sought the door. Logical fear said “do that.” The follow on thought to the above were joists letting go and I didn’t want to be there for that. Nothing happened, but that is what drove my fear. (two story apartment)

          • 5.5 for me – but I was quite a way from the epicentre. It was in the middle of the night and seemed to go on for ages but it was only about 20-30 seconds. That was in the Great Rift Valley and we often had 3’s and 4’s which were just unsettling. The bigger ones were scary in a very atavistic way – we rely on the ground beneath our feet and when it moves a very primal fear kicks in.

        • Experienced a 5,6 in Carlsbad, CA back in July ’86 in a beach-house. The bed shook, and the chairs moved. Beeing a Norwegian I thought I was going to die – but it only lasted 10 – 20 seconds and all went calm. Untill that day my “dream place on this earth” was southern california…. left the next week and have only been back for holidays……

          • St Helens was different – too far away for any shaking beeing just east of Connell Washington, but they used plowes to take the ash away the next days..

  15. For those in UK who can’t take any more excitement and want a bit of respite – BBC1 are about to show a programme on what actually happened to the people at Pompeii when Vesuvius went bang. Forensic scientists examine the body casts and recreate the last moments of the people, including facial reconstructions. A bit heavy on reconstructions, according to the Radio Times, but maybe worth a watch if you are interested in the effects of volcanoes on people. On at 9.00 pm

    • I wouldn’t actually count much on the calming effect of a film about people who died in pyroclastic flows …

        • Well you know, one of the glory of french cuisine is lamb’s brain cleaned and cooked in a pan….that was before mad cow’s disease

          • Sorry, should have said transmissible to other sheep, most likely not to humans. However I for one would be very wary of brains from any animal.

          • Mad Cow, BSE, and Creutzfeldt–Jakob disease are all cause by a malformed protein that is folded improperly. How it progresses is that it encourages other proteins of that type to also fold into the wrong configuration.

            If the malformed protein (prion) is close enough in configuration to a protein in a different species, it can probably cause it to do the same. In that case, it would be able to hop species.

          • Yes, it was suggested at one time that cattle were being fed protein from other animals, possibly sheep. Not sure though if anyone ever discovered the real source of BSE developing in cattle. Not really interested to do more research but maybe Diana having been a biologist would have more interest in the subject.

          • BSE prions were transmitted to cows from feed made in part from cows. No evidence thankfully that BSE is easily transmitted to humans (but it might just be *very* slow to develop, we are not entirely in the clear yet). BSE is distinct from scrapie in sheep, which is regarded as harmless to humans.
            Kuru is the human version,found in PNG populations where women and children ate brains of the deceased.
            But relationship of these with CJD uncertain.

          • we have also this speciality of “sweetbread” which is a lamb’s or calf thymus. Very tasty cooked with some garlic and parsley. A delicacy. 😀

        • Oh please, dfm, stop talking about delicacies! I never really had an inclination for cooked animal intestines but from now on the thought of it will be hardwired to the image of screaming people and exploding skulls under Vesuvius. 😉

          • I had sheep’s intestines in Spain and they were surprisingly good. I didn’t know that’s what they were until I’d finished them though.
            No amount of talking about boiled brains is going to put me off my supper.

          • Well… yes it was a bit grusome but the recreations of the two people were amazing. I’m definitely going to visit the Pompeii Exhibition at the British Museum this year. As for cooked animals, I’m pleased to say I’m a vegetarian so I won’t be worried by visions of cooked people!

          • @ Talla

            No, but if there is any chance of ‘you’ being that “cooked person”, you might be more than a little worried about it! – vegetarian or not!

            So all out there living in the shadow of a restless volcano: don’t watch until the threat diminishes!

            (Sorry, but your innocent attempts at diversion really made me giggle)

  16. I posted this a few weeks ago, its ground deforfation at one of the meters near Hekla. It shows a steady trend to the north-west. If you notice the normal east motion, it started moving slowly north and then west in October to December timeframe.

  17. This is the update till 18h43 today

    Today there were a number of strong (for El Hierro) earthquakes with quite a few over mag 4 which is quite rare.

    In the list of earthquakes you will notice that the for strongest earthquakes there is only one event of similar magnitude (4.6) and that in all the events with mag >=4 (16 out of more than 17 000 !) 5 came to happen today.

    2012/07/03 02:26:51.78 27.6808 -18.1464 3.4 3.2 17 20.4 3.1 4 0 9 9 0.12 259 1153621
    2012/07/10 04:04:34.69 27.6812 -18.0654 3.4 2.4 180 21.6 3.9 4 0 8 8 0.16 171 1155730
    2013/03/25 05:57:21.38 27.7652 -18.2289 4.5 3.4 138 15.8 2.9 4 0 9 9 0.12 316 1200192
    2012/06/27 18:55:08.78 27.6894 -18.098 3.8 2.7 57 19 3.4 4.1 0 8 8 0.07 256 1152007
    2012/07/02 22:42:38.92 27.6984 -18.1393 3.2 3 137 18.9 3 4.1 0 9 9 0.12 210 1153536
    2013/03/25 14:41:39.67 27.7688 -18.236 4.6 3.4 137 16.1 3.2 4.1 0 8 8 0.12 318 1200452
    2013/03/27 15:28:55.97 27.7313 -18.2962 10.4 6 178 12.2 6.6 4.1 0 8 8 0.41 333 1201300
    2012/07/03 02:31:02.60 27.6871 -18.1706 4.6 3.6 66 20.4 3.2 4.2 0 8 8 0.11 306 1156549
    2011/11/02 07:54:55.88 27.7808 -18.05 3.4 1.9 168 20 3 4.3 0 9 9 0.12 218 1109562
    2011/11/02 18:10:39.98 27.788 -18.0576 3.7 2.1 167 22 3.1 4.3 0 9 9 0.14 227 1110025
    2013/03/27 15:02:15.29 27.7499 -18.2749 10.9 6.8 176 18.2 6.8 4.3 0 8 8 0.11 331 1201313
    2011/10/08 20:34:47.92 27.6285 -18.0124 2.9 1.7 180 15.1 2.9 4.4 0 9 9 0.61 241 1103959
    2011/11/04 20:36:28.02 27.7699 -18.0395 4.1 2.6 167 21.8 3.2 4.4 0 9 9 0.13 197 1110303
    2013/03/27 16:10:55.26 27.7792 -18.2906 6.1 4.6 14 11.3 2.1 4.4 0 9 9 0.25 329 1201326
    2011/11/11 00:20:16.73 27.7795 -18.0543 3.5 2 165 20.7 3.2 4.6 0 9 9 0.12 219 1111925
    2013/03/27 15:07:55.98 27.7231 -18.2669 7.4 4.7 167 19.3 3.3 4.6 0 8 8 0.11 330 1201310
    Dia Hora Lat Lon Smax Smin Az Pro epro mblg inten nsta nPd rms gap evento

    Without wanting to be fearmongering, I find this situation unprecedented. If you add this to an also unprecedented trend in the upward component of the GPS, this situation begins to pose a number of questions. Happily (if one may say) the bulk of the seismicity is located at sea and not on the island emerged part.

    Meanwhile here is the earthquake update for the period since March 26th 8h18 and 27th @ 18h43. It includes the 4.6 quake.

    The color of the quakes is linked to their position on the list (more than 1200 events since March 18th).
    I will probalby change this next time as the color scale loses its interest.

    It is interesting to note in the time lapse animation that there are first some cluster of quakes in the previous parts, leading to an hypothesis of a “sill” of sorts or at least to an accumulation of rock breaking in the same place. Then most of the “strong” (meaning over Mag 3 ) quakes seem to appear on the border of that cluster (look at 0’20”). Could it be that there was some renewal of magma arrival (a new “bolus”) and that the constraints bring some rock breaking on the limit of the previous cluster. I will only repeat that these new events happen in a zone previously devoid of earthquakes.

    The 4.6 event can be well see at 00’49” on the center-left part of the plot, over the 27,6 mark on the abscisses.

    Do look at the end of the video in the zoom sequence (1’22” and 1’28”)

    On the right side of the colorbar the terrain elevation scale is shown. Magnitude of the events (sorry I stopped at 4 !) is shown on the lower part of the plot.

    Data from IGN and NOAA, made on Gnu Octave.

    • Brilliant piece of plotting again dfm (I picture your domestic scene: “Hey honey, come and look at this dike! Do you think it’s a diapir? Oh, and I got the pics of the dead fish” – yeah, I wonder what the neighbors think?) , though once again I am kind of flummoxed by the timing and spread of the activity. I can’t see a sill there, if anything it looks more like a dike, but a pretty strange one, cause it seems to spread downwards as much as it spreads upwards/sideways.. I dunno. I can’t make head or tail of it, put there is some pretty serious fracturing going on there, which if nothing else, is indicative of the pressure in the system.

    • Bearing in mind the GPS stations are ~15km away from the swarm centre the 100mm uplift in ten days is unusually high for Hierro. Previous swarms have been co-located with the GPS stations and resulted in smaller uplifts over longer periods,IIRC.

      • Lurk mentioned the other day that he got some horrific figure from his Mogi calculation so he assumed he must have made a mistake… maybe he didn’t !

        • I wonder if the uplifts could be plotted across the island E-to-W to give an extrapolated value at the swarm centre?

          • Roughly speaking, I reckon there could 200mm uplift above the swarm. That’s assuming uplift from there to Julan and Restinga is linear. Neither of those stations has lifted, and H105 the lighthouse is roughly in the middle of that line with 100mm uplift. Ballpark guess,no more.

  18. Debbie, can you give us the link to the dead fish pics please ?
    ps : (I wonder what some exterior people just getting on this blog would tell themselves (something along “yuk, just a band of maniacs doing weird things while looking at dead fish pics” – chill out, we’re just volcano loonies….this is Not 4chan)

    • Hi dfm, I watched the news on TV Canaria, but have tried to find their web page and it is a nightmare of advertisements etc – the news programme I was watching was called Abierto…sorry but I cannot find the programme or this article on internet to post a link …I assumed that the dead fish was current news, but of course with the media, one never knows if they have pulled out some old footage to boost the interest in their current report…If I see or learn anything else regarding the fish I will post here straight away.

    • Another Brilliant animated plot dfm. Thank you for all this hard work. I have looked and looked and I too cannot work out any “system”. I thought there may be a largish vertical fault maybe that is producing a sill rather than a dyke. I really don’t know or even difficult to hazard any guesses. It does look as though this pulse maybe moving south though. Oh for z-ray eyes, but dfm’s plots are the nearest we can get to this.

  19. It really bothers me that you can see quakes on the tremor graphs but not the map. I guess they are triple checking their math.




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