Bárðarbunga loves Grimsvötn = True

Photograph by Eggert Norðdahl. All rights reserved and used under permission.

Photograph by Eggert Norðdahl. All rights reserved and used under permission.

I once again reiterate that it is Icelandic Met Office and Almannavarnadeild ríkislögreglustjóra that has the authority to issue warnings for Iceland in regards of eruptions and jökulhlaups.

For airborne ash advisories it is in the following order London VAAC and IMO that issues advisories. That being said here follows a brief update upon what is happening in Bárðarbunga and Grimsvötns fissure swarms.

Volcanic love in the ground

Who would have thought that the two largest volcanoes of their type on earth could make love to each other? Well, let me expound a bit on how they do it physically. For anyone who is a bit sensitive, this is where you should stop reading. It will get very graphical.

Since the seismic swarm started there has been quite a lot of confusion about what is going on, and where it is going on. Thanks to the Icelandic Met Office (IMO) we now have answers to our questions, and what glorious answers those are.

The reason the picture has been so muddy is that IMO has been swamped by earthquakes. So they have not had the time to manually correct every single one. Instead they have concentrated on the larger ones since they have a much higher importance. Remember that one M2 earthquake carries the energy of 31.6 M1 earthquakes. This means that IMO has only corrected the large ones and the smaller has been left hanging around.

Now, small earthquakes gives less clear signals compared to larger earthquakes, so the smaller the earthquake, the larger the errors. So, many of the uncorrected earthquakes are several kilometers off in all directions. Think of this as a blurry picture. In this case so blurry and out of focus that what actually was going on drowned completely.

Now thanks to IMO we have maps only containing manually recalculated earthquakes, and due to that we can see what is going on and where it is going on. And out of the mist a scene of unadulterated volcanic lovemaking emerged.

Volcanic fissure swarms

The large Icelandic volcanoes are situated on something called fissure swarms; those are permanent thin areas of the crust that are permanently weakened as the continental plates pull apart. They are in a sense of it the actual rifts where the Mid Atlantic Rift (MAR) pulls apart.

Under Vatnajökull there are at least 3 fissure swarms, Bárðarbunga fissure swarm (Veidivötn to the South and Dyngjuháls to the North) Grimsvötn fissure swarm (Lakí to the South and Grimsvötn to the North) and Lángisjör. The last one we can leave for now.

On the fissure swarms you have central volcanoes. 3 are known for the Bárðarbunga fissure swarm, namely from North to South Kistufell, Bárðarbunga and Hamarinn. For Grimsvötn you have Grimsvötn, Háabunga, Thordarhyrna, Geirvörtur, Háagöngur and Éldgigur.

The central volcanoes interact with their fissure swarms in many intriguing ways. But it has been the general opinion that each fissure swarm is a system on their own. There are a couple of hypothetical places where it is suspected that some sort of mechanical interaction could exist, but there has never been any clear cut proof of it. And there has never been any proof or even a causal chain proving movement of magma in between them.

Untill now. First I need to explain one last detail before we get to our lovemaking fissure swarms.

Radial fissures

Radial fissures are fissures that extend outwards from a central point, in this case a central volcano. Think of it like the spokes on a bike wheel. Several are known for Bárðarbunga, the most well known is the Gjálp fissure that erupted in 1996 that extends from Bárðarbunga towards Grimsvötn.

Love is in the ground

Image by Icelandic Met Office. Note how the magma moved out from Bárdarbunga down the radial fissure, and then make a sharp righthand turn as it meets the Grimsvötn fissure swarm.

Image by Icelandic Met Office. Note how the magma moved out from Bárdarbunga down the radial fissure, and then make a sharp lefthand turn as it meets the Grimsvötn fissure swarm.

In the beginning there were two earthquake swarms. One happened at the Kistufell central volcano. We can leave that one be today. At the same time a small swarm happened inside the central volcano of Bárðarbunga that quickly moved into and along a radial fissure.

As the magma followed this radial fissure it went so far out that it encountered a new feature, the Grimsvötn fissure swarm. At that point the magma was injected into a more fertile ground and for pressure dynamic reasons it could not go towards Grimsvötn, instead it started to move further down stream of this new fissure swarm.

Now I just hope that Bárður and Grims baby will not take 9 months of birthpangs until being born.

I can’t stress strongly enough how surprised I am about this. It is the single biggest surprise in my volcanic days. It is surprises like this that makes life truly worth living.



753 thoughts on “Bárðarbunga loves Grimsvötn = True

    • Thursday
      21.08.2014 23:50:20 64.620 -17.459 4.3 km 3.3 99.0 4.0 km SE of Bárðarbunga

      upgraded to 3.3, but will probably be rehcecked again

    • Strongest since beginning of this, also reord number of quakes last 48 hours
      and its “spiking” again (signifying increase in risk it possibly maybe imminent)
      *not expert*

      Fjöldi skjálfta (0045 hrs):
      Stærð minni en 1 alls: 464
      Stærð 1 til 2 alls: 1406
      Stærð 2 til 3 alls: 221
      Stærri en 3 alls: 11
      Samtals: 2102

  1. Islander / Irpsit or any other Icelanders. What is the local gossip about this event like? Are people just assuming it’s going to be another Eyja or Grimsvotn?

    Also – I predict we’ll see quite a few more 4+ earthquakes. I don’t think this is going to blow any time soon personally, but if it does erupt sooner than later, it will definitely be from Bardarbunga itself.

    • Personally think more like Gjálp, but unshure of how large or small an event. Gossips do not count 🙂 Statistically small but in increased hotspot-cycle could be larger. *not expert*

  2. We have another star now, but this one further north at TFZ:
    01:26:29 66.223 -18.226 11.4 km 3.3 99.0 5.8 km NNE of Gjögurtá
    Interesting to see the hard time Mila’s Bárdarbunga webcam is having with focusing. Probably due to constant tremouring? Take a look at the pebbles on the foreground: they keep coming in and out of focus. Never seen such a weird anomaly.
    Chryphia and dragons: maybe you could save Irpsit’s description of present panorama in the Bárdarbunga summary – Spica is not available for that purpose. His comment is a jewel to be kept as a treasury, isn’t it?
    Three more of those M4.5 or larger could make an eruption, couldn’t they? But skies over Iceland couldn’t be any clearer.
    What the heck is going on?

    • Absolutely should be saved! Not daring to do it right now, because being internetly challenged like Spica right now 😉 …can’t wait to see webcams and videos again.
      Otherwise, fantastic work everyone here, updates rolling in in almost realtime, love it!

  3. Mini-Report 2:

    None of us commented on this one at the time it happened so I’m assuming it has been upgraded:

    21.08.2014____22:44:58____64.681–16.998____12.3 km____3.0____99.0____14.9 km SE of Kistufell

    That was followed by the BIG one of the night!

    21.08.2014____23:50:20____64.620–17.459____4.3 km____4.7____99.0____4.0 km SE of Bárðarbunga

    and everyone still awake commented on this one! (go back a page for the start of the excitement) 🙂

    Then all went quiet at Volcano Café so I pulled the curtains closed, snuffed out the candles, poured another coffee and prepared to take the night watch. With pen and paper at the ready, I decided to fill the quiet hours with some stats.

    As of 5:10am local time, Barðárbunga experienced 28 earthquakes over magnitude 2. All but one (in the NNW) occurred in an arc from N to SSE so the east side is getting a pounding, especially in the N (3), NNE (5), NE (12) and E (2) quadrant where 22 of them have taken place. I don’t know from which point at Barðárbunga distances are being measured but I can tell you that just one was as far out as 8.8km, another six at 5-6km out and the remaining 20 within 5km, with the nearest registering a distance of just 1.1km. Seven of those earthquakes have registered a magnitude greater than 3. In order of magnitude they have been:

    3.1 — 3.2 — 3.4 — 3.4 — 3.7 — 4.0 — 4.7

    In chronological order, they are:

    21.08.2014____23:50:20____64.620–17.459____4.3 km____4.7____99.0____4.0 km SE

    21.08.2014____17:44:03____64.677–17.468____4.5 km____3.4____99.0____4.9 km NE

    21.08.2014____13:02:08____64.678–17.470____4.9 km____3.4____99.0____5.0 km NNE

    21.08.2014____10:58:09____64.670–17.456____3.1 km____4.0____99.0____4.8 km NE

    21.08.2014____10:29:07____64.613–17.487____2.7 km____3.7____99.0____3.6 km SSE
    20.08.2014____23:38:04____64.618–17.466____8.5 km____3.1____99.0____3.8 km SE

    20.08.2014____16:14:04____64.669–17.462____3.1 km____3.2____99.0____4.4 km NE

    May you all be sleeping well and awake refreshed. 🙂

    • As long as you have the night shift it’s almost better to come on here first than go straight to the IMO site. The only information missing from your summary is that post the 4.7 in Bardarbunga, every other 2+ quake up to the most recent one displayed by the IMO occurred along the Eastern or Kistufell branch. Nice going for a “newbie”!

        • It’s interesting, isn’t it. I started looking at the earthquakes over 2 just for Barðárbunga and thought at first that all were on the eastern side until I found that one NNW! But once I had them all grouped together, it seemed only logical to continue on and see what else I could separate out of that grouping – it was fun! 🙂

      • Thank you! Had to fill in the ‘quiet hours’ with something constructive for you all to wake up to! 🙂

      • Actually, every one of the seven listed in chronological order all happened at Barðárbunga according to IMO. For the last 48 hours from 5:10am this morning, none higher than 3.0 occurred along the Kistufell branch.

    • And congratulations to all the Bank Holiday travelers as even if BB blew now, the ash wouldn’t get to the UK until Monday even with a wind shift. Seems they can have their get away and even get home. Love your updated plots, really should charge the aviation industry consultancy fees DU!

  4. Hmm, on the drumsplots I see something on 4:00 and I think that was not such a small one. Its showing on several drumplots but not on the IMO site. Am I mistaken?

  5. Thanks all! And thanks for the bated correction: I should know better, given my educational background. 🙂 It seems to me, looking at the color coded chart of ‘quakes over the last few days, that “something is coming” (HPL From Beyond quote, sorry) based on the diminishing area affected and the continuing prevalence of activity. But maybe it will just curl up beside itself and settle down.. Hard to say, eh? Exciting times!

  6. Pingback: Vol. 1 / No. 43 – Icelandic Eruptions, Plankton in Space, and How Diabetes Happens | ThisWeekInTomorrow

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