Reykjanes surprise

Source: https://www.visir.is/g/20212093433d/ny-sprunga-ad-opnast-a-reykja-nes-skaga

The eruption in Geldingadalir seemed to be waning. The flows from the two cones were notably weaker this morning. The cracks in the back of the cones which has been emitting steam had stopped doing so. The raised lava pool in front of the cones was emptying, and earthquake activity was almost absent. Activity has gone up and down over the past week, but this was definitely a down. Even the Icelandic activist making a nuisance of themselves in front of the cameras (and not being a particularly good advertisement for the country) were largely absent. The valley was largely filled with lava but the edges were not rising very fast. Yes , the eruption was definitely in advanced middle age.

At 11:32 today UTC), weak earthquakes occurred in the area. They were only about 1 km deep. At 11:37 a stronger event happened. And suddenly, reports appeared of a new fissure which had opened. By luck, it was in view of the main camera (but behind the second one) and we had an immediate good view. The fissure is perhaps 500 meters long, is showing weak fountaining along its length, and is producing some lava. It is located 1 km northeast of the twin peaks. That puts it along the dike, and this is clearly fed by magma in the dike.

The location is on the high plateau adjacent to Geldingadalir. We have had discussions which way the lava would take out of that valley; the most likely route involved a roundabout way to get to the Meradalir valley. It was unlikely to make it at the current flow rate: it would likely solidify on the way. It turns out, the lava found a better way, underground. The new fissure is near a gully that empties into Meradalir. The lava quickly found its way into this gully (which is no more), and within hours reached the floor of the valley. It is now expanding into Meradalir, albeit out of sight of the cameras.

The map shows the approximate location of the new fissure. The accuracy is not guaranteed! (This is an updated version, which moved the fissure to the far side of the gully). (Update 2: the extended fissure is beyond the gully, as pointed out by Reykvolc. This has been added to the drawing.)

The map shows the Geldingadalir flow, as it was expected to develop. The yellow area shows what was needed to get an overflow into the next valley, with a roundabout path to the lower valley of Meradalir. The magma decided against this and choose a short-cut instead. The red line show the new fissure (it is a bit guess work and I have assumed it is perfectly aligned with the original fissure which may not be true). It shows the two gullies, and indicates the one which the lava has chosen.

What caused this new fissure? There are two possibilities. One is that the magma pathway to the twin peaks was beginning to be blocked, and that the backed-up underground flow found a new weak spot. The second possibility is that the dike was slowly closing as the magma inside was cooling and that this squeezed out the remaining liquid. To tell we need to know the composition of the new lava. It is hard to tell the viscosity when it is flowing through such a steep gully.

How will it evolve? If it behaves like a normal fissure, then the new eruption will quickly focus on one or two spots, with the rest of the fissure ending its activity. This may be happening already as most of the fountaining now comes from two or three spots at the middle of the fissure. However, there is also new fountaining activity at the end of the fissure where it approaches the gully. A southerly extension of the new fissure has opened up here in the past hours which may take over from the earlier fissure. Four cones can be recognized along the fissure, including two in the new extension. The northeastern end of the fissure has a ridge only.

https://www.facebook.com/Almannavarnir/photos/pcb.4244255905606160/4244254928939591

We already have the first time lapse of the new fissure, thanks to astropgrah99

It is guesswork whether this new fissure will become the main eruption site or that it will be a short-lived excursion. It is fun to guess though. If it continues, the fissure could extend further towards the valley, purely because that would be a shorter way to travel for the magma. It may be time for a new camera.

How about the old eruption? The activity there remains notably weak. The two cones are slowly being eaten away from the inside, with frequent minor collapses. The cones are both cracked and if the eruption continues, may collapse. The surface flows now stay close to the cones. They have build up a lava pond enclosed in levees, and every now and then a levee develops a leak and a break out happens. Much of the flow is out of sight. The flow rate is hard to judge by eye. The composition remains fairly primitive (for Reykjanes), suggesting this is magma that had collected around 15 km deep at the interface between the deep crust above and the mantle below. how long it spend in the dike is not known, but there was no indication that the magma was aging during the eruption. That would be expected if the eruption was fed purely from the dike.

Time lapses of the ‘old’ eruption thanks to Virtual

Finally, the poll we had on the duration of the eruption has given a clear winner. We had over 500 responses, from 40 different countries as far apart as Greenland and New Zealand. Regrettably, two voters had to be disqualified for submitting multiple identical responses. The electoral authorities in their respective countries have been informed. After this edit, we received the following votes (note that ‘Longer’ means longer than 5 years):

Interesting, if we look at votes from Iceland only (in the ranking of umber of voters per country, Iceland was fourth), a different picture emerges:

Are these votes from the Iceland tourist board? I guess time will tell! So far, this is a typical Icelandic fissure eruption with a dike, multiple eruption sites and some but not enormous amounts of magma. The only uncommon aspect is the lack of involvement of a central volcano. We do not expect that a central volcano will develop here: that is not the way of Reykjanes. Once this eruption is over (whenever that will be), the next eruption will occur somewhere else on the peninsula and it will firget about this fissure.

There have been suggestions a shield may develop here. That would be most unusual, but cannot be excluded. However the new fissure indicates that the eruption has not yet reached stability. Wait and see. Iceland may yet surprise us. Again.

Albert

686 thoughts on “Reykjanes surprise

  1. Fissure 3 certainly unzipping towards Twin peaks, there is a long sputtering line behind the new lava river.

  2. The lava is so hot that the camera sensor is overloaded with a lens type glare, from the 2nd fissure area, but the new middle 3rd set is very hot too, glaring white hot, very hot and it appears that the cones have increased in intensity too.

    I am quite concerned by how hot the 2nd fissure has gotten, the lens glare is very noticeable now sometimes very much so.

    https://www.mbl.is/frettir/innlent/2021/04/06/baedi_gossvaedin_i_beinu_streymi_a_mbl_is/

  3. I haven’t been watching all evening, but is it possible that a graben opened between 2 and 3, and that lava is flowing from 2 downhill to 3?

    • there was no flow there at all, the flow was going down the first channel, then it started down the second. I believe that the ground simply split open all the way from the 2nd to the 2 cones. We did see the fissure moving from the 3rd area towards the cones and that was verified.

  4. I have taken some pictures with my Apple Iphone, the area between the old cones and the 3rd fissure area suddenly flares up without warning and once, it was bigger than anything else in the camera. I would be very careful of being near this area. Can someone back up the tape to 03:15am and look for the first big flare?

    • The 3 channel just overflowed, but stayed in front of the camera. I know it was the optics of the cam, but the flow looked bright blue!

    • That breakout looks to be ever so slightly downhill from the camera
      If I’m not too mistaken, if you look at the RUV Gelding cam and check out the stream from the new fissure to the twins. Midway there is a sudden change in angle (slope) with a little random fountaining, right below that there’s this small reflection one in a while. I’m pretty sure that that’s where the mbl cam is

      • That’s around where I’d put it too. A breakout would need to be much higher to endanger the camera. Time will tell, I guess. I doubt it is worth the risk of rescuing it anyway and the drama of being devoured alive will be worth the cost of a camera.

  5. I think that K100 camera might be a little higher than it appears due to magnification of the foreground.

  6. Okay, I caught the bright flare up the 2nd time and this time I have pictures. It is near the two cones.
    You are taking your life into your hands if you happened to be walking along the fissure when this flare up occurred.

    • I saw the bright flare too, it is from the crust foundering on the flow not a new vent.

  7. Looks like another breakout from the flow above the MBL camera… 🙁

  8. It seems the path to Meradalir has been blocked: no active flow towards that valley at the moment.

    • There is another flow from that vent going the other direction. It looks like there isnt enough flow from just that vent to go in both directions. My guess is that each individual vent doesnt go much above 5 m3/s, it seems at the moment it is easier to create a new fissure than it is to increase the output from an existing one. Probably this will be the case until theres just one continuous fissure along this whole area from Natthagi up to the top of Fagradalsfjall, then that will evolve back into a central vent that is not necessarily at the location of any of the main cones now, and that vent will have a quite substantial effusion rate to create lava flows that go a lot further.

  9. We know the fissures are connected beyond the ridge at the green line, but the lava has been ever so slowly moving towards the camara roughly on the red line. So we might/will probably get a kipuka here. There’s actually plenty of kipuka potential around the place now.

    • That ridge of land between the two gullies with lava rivers is a large one now. It’s cut off by the Easter Monday fissure lava flow at the top, on both sides by the lava rivers, and at the bottom by the huge pool of lava in the valley bottom. Hope there isn’t any wildlife trapped on it.

      • Should say is nearly one, now I can see a little better as the snow and mist lifts. It looked like they joined last night in the dark onthe webcam, but no, not quite yet!

  10. Think they can be needed to move the camera soon.. Nr 2. or what they call it now. So now cracking up back against the first place. Think Albert talk about that.. Now the valley can be filled up little faster. and it get a flow out where we first talk about.

  11. if you look at this livestream

    https://www.mbl.is/frettir/innlent/2021/04/06/baedi_gossvaedin_i_beinu_streymi_a_mbl_is/

    you can actually see exactly why the flow into Meradalir stopped, the side of the cone feeding that flow failed and nearly all the lava from that vent is flowing in the other direction, it is going towards Geldingadalir just like the newest fissure. looks to be a strong flow too, not at all weakened by the opening of a further fissure.

    • Good camera view.. New went look like it can send flow little all over the place.. sit right on small hill i think. if so it depends where overflow go.. easy to get fooled with topography and i havent find a real good map

  12. A flight over aria now and photo would be very nice. But think it is little windy..

  13. Ok so, twins erupted just because they were at a low point of dyke profile and of course due to some earth priviledge that was there (meaning maybe an old lava tube as somebody presumed so days ago here) now, finally the dyke got power and create the fissure…That’s my picture of the event. The idea is that now, wouldnt be the twins working progress the motor of dyke pressure build in future? Is that to be expected or simplly the twins will drain it out faster?

    • Could be but really this sort of low level activity is typical of rifting eruptions like this. Look at Krafla, it began with an eruption that was very small, up until 1980 probably any eruption was really accidental from a dike gettign a bit close to the surface, activity was mostly or entirely intrusive, up until the rift was full and suddenly the magma had nowhere to go except to erupt, then the eruption went from tiny up to somethign with a comparable intensity to Holuhraun in 1984.

      What we have seen so far though is just the beginning, the very very early beginning. Think Kilauea in 2018, how extremely tiny and atypically small it was for that area when it began, vs just a month later when we had a second Holuhraun in the middle of a town that raged for 2 months at a rate that was comparable to its entire first 2 weeks of output every 12 hours… It will be that sort of stark difference

  14. I’am also intrigued by the steady smoking point (now actually kinda crack) on the shoulder of the left vent…is there by two or three days…and is growing…

  15. Hard to save it. Bad weather also.. It comes a new stream that maybe is right on

    • I would leave that camera up any time I was at the computer, will be sad to see it go.
      Should hold a wake for it, though it is too late in the day here (almost 5:30pm) for coffee. There are alternative beverages, though 🙂

  16. Looks like that K100 MLB camera is finally in danger. A few more meters sideways movement could take it out. It should be feeling the heat I imagine.

  17. Just trying to work out what has happened overnight – where is that flow on the mbl camera (the one about to be engulfed) coming from?

    • A breakout from the new vent around the point where the slope changes down.

    • it open a 3 went between first and second.. and that one send a stream back to valley it all started with.

  18. To quote Maxwell Smart: missed it by that much! It’ll be a shame if the original MBL cam goes, was often the best and highest resolution view.

    P.S. been reading this site since Bob / El Hierro, first time I have de-lurked.

  19. The sheets in the lava flow are so strikingly similar to pack ice driven up by currents.

    Hard to imagine two things more different than sea ice and a lava flow, but yet so similar. Nature works in the same way at many different temperature ranges.

    • I have been mentally comparing and contrasting the geomorphology of this eruption from when we started to get visuals. I was glued to the live stream, getting on average 4 hours sleep every night and reviewing that footage on wakening. Blurts and triumphant exclamations have issued randomly from my mouth as similarities hit my brain, so I’ll offer up some examples:

      Lava pool draining looked like a flash flood after crossing a road and hitting rougher ground , interference waves and chaotic disturbed surface.
      Empty lava pool looked like a paddling pool emptied for maintenance. Ridges of spatter collapse material looked like eskers on a glacial outwash plain.
      Lava channel edges like river levees, built up by small overtopping slops and surges.
      Surges after collapse like slow motion tsuamis travelling through the lava as a wave.
      Cone collapses like icebergs calving, the smaller debris like bergy bits and brash.
      Overturning/foundering sheets like icebergs, bumping and boring, sliding up and over into pressure ridges like ice, river flooding debris, ice on a lake when breaking up.
      Slow lava in backwater channels a getting smooth flat surface in a low energy environment, like the conditions in a cut-off meander or ox bow lake.
      Cliffs and eroded flat surfaces around the lava lake, like coastal retreating cliffs with wave cut platforms.

      I could go on, and on, and frequently do… *any comedic reference here is entirely uncoincidental and any comment will be welcomed by a murder-mitten swipe*

      (My house is a tip, the laundry abandoned, the only chores done are essentials of food prep and consumption. Gentle and not so gentle protests are being made, to whit, the reply: “it’s been 780 years, dammit!”)

      • Well written….thanks 🙂

        Yes, I too have been thinking of similarities with ice, that being the only thing that I could compare it to.

        Households around the world have collapsed….chores piling up like lava dikes, wonder how the breakouts would look like… 🙂

  20. Should have a build in drone. so it could take off.. Well it done its job good. Samsung Can send a new one..

  21. On the CAM Ruv Geldingadalir you should see the flames at the end of the cam mbl.is
    Because of the snow it is not possible to estimate the distance to the lava.

  22. Ok back to more volcanic things.. crise above was in to it little. What is the background things to create this situation.. Is it that that the main source from deep have fill up all cracks and cavitys now so pressure go up so much in the that it open more fissure vents. You could think that it would be easyer press up more at the main (1) instead because it is already a opening there. Or is the tubing to narrow in that spot. I think i read that it was around 20m3/s and the wents get out around 3-5m3/s each,. So in my mind it should be enough to have 2 more vents going.. but as i say i am only in beginning of this 🙂

    • The question is also if the effusion numbers are for the DRE or the actual lava. Lava is about half the density of solid basalt, so 5 m3/s DRE is more like 10 m3/s lava, its even more if the eruption produces tephra which is why Grimsvotn gets impressive numbers in 2011 (nearly VEI 5 but only 0.3 km3 DRE).

      The supply to the dike will be in DRE, so depending on the above there is enough room for either 2 more vents or maybe as much as 7 more. 10 vents at once… 🙂

      This also doesnt include the possibility of the magma flux increasing even more if rifting continues, or the magma melts the bedrock to expand the pathway, or the lack of pressure at the source inducing further decompression melting. Normally that doesnt happen but it is easier at depth where the rock is a few hundred degrees already and the lava is almost 200 C above its solidus temperature.

      • 1220 C are some reported temperature measurments… the new cone had yellow lava spatter in daylight. Spatter cools quickly on the surface… but some are yellow here and perhaps brigther inside… this lava is really hot.

        https://www.facebook.com/volcanochaser/photos/pcb.117662637081549/117662577081555/
        https://www.facebook.com/volcanochaser/photos/a.102460741935072/118193403695139/

        This lava is hotter than most Kilauea eruptions and in Line with Halemaumau lava lake open conduit siutaions in temperature. Its very hot beacuse Reykajnes haves only a thin crust and the 1300 C astenosphere is very close to surface. Reykajnes 2021 is feeding from a large deep magma accumulation zone in the reykjanes rift… so haves the potential to last many many years.

        Most other basaltic lavas barely reaches above 1100 C

      • Ok tanks.. That clear up little. Have work little with pressure things but with this it is many parameters. More easy when you work in same temp and same diameters all the time. Here it is background heat and more.. Going to take some time get my head around it.

  23. Hard to catch up, after a longer, unusual break of lurking… 😬

    Thanks for describing this impressive event smart girls and boys!

    After reading all comments, I admit I lost track a bit what, where is happening. Someone can post a sketch map where lava is flowing in which direction please?
    Looking at k100 this morning was a shock… lava flowing just before its position…

    Before the second fissure opened, it looked like we had seen the most of the eruption. But looking now, I have the impression the total outflow is larger than at the start of G. The twin cones have become more active too again.

  24. Like Rob I am a bit confuddled. I need time to get to grips with the changes and cam views.. To make matters worse Drain men arrived with mini digger at silly o’clock this morning and hadn’t notified us. We thought maybe that the work had been cancelled for today. Had to alert neighbours the track behind the houses will be closed. Anyway.. I will have time to catch up later. Thank you everyone for your reports and links. For now I have to walk the dogs…….

  25. Like Bob am losing the track of events.Did a fourth fissure occur? Just had a look at the cam -it looks like the twin cones got less active. Again I hope someone at Volcanocafe could write a summary of the eruption/eruptions.Do enjoy everyone’s input .

    • No 4th fissure yet but the original cones are most likely the second player now. Fissure 2, or rather cone 2 now, is by far the most productive, it has at least 4 lava rivers flowing from it right in view of the webcam now and is getting on 30 meters tall or more, with a vigorous lava lake and fountaining within it.

      This one can be called Steve 🙂

      • It will be called Morgoth…

        But Gollum and Smeagol vents are still alive… perhaps forming a little shield

  26. Someone on this blog asked what the Hawaiian word “kīpuka” is in Icelandic.
    I just was learning that this morning. kīpuka = óbrenn­is­hólmi (óbrynn­is­hólmi)

  27. Seems to be the old cam on the mountain north of Meradalir, but now zoomed in.

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