A while ago Jesper Sandberg asked a question about if Grimsvötn could sprout forth a lava lake. I somewhat sloppily answered that I did not think that it was possible. Jesper then asked why not, and I got somewhat flustered since I did not have a ready answer. I promised to come back with a good answer in the form of an article.
I thought that would be easy and earmarked the next weekend for a short article on the subject. Oh my, what a case of hubris that turned out to be. Week after week I had to postpone the article while I pondered things.
The problem is that we do not know a lot about lava lakes, in fact we know less about lava lakes than any other type of eruption. This is a bit odd, since they are the most openly visible type of eruption there is.
I have often stated that the edifice of a volcano, and indeed their eruptions, are just the effect of the cause that is the real volcano, and the real volcano is lurking at depth, often coming into being tens of kilometres down, or even hundreds of kilometres down. What we see is ruled by the unseen plumbing deep down.
In other words, just because you can see things in a spectacular fashion, it will not help explain what is going on at depth.
Lava lakes in general
Let us start with summing up what we do know about lava lakes. They normally form on large volcanoes that has a high lava temperature, Kilauea, Nyiragongo and Erta Ale are perfect examples of this. All of them are fed in turn by hot magma coming up from extreme depth via their respective mantleplumes.
Then we have Mount Michael, Yasur, Ambrym and the others who are fed by subduction and back-arc volcanism of a type producing hot basaltic lavas. The oddball is Mount Erebus that has a lava lake that is colder and contains more evolved lavas.
Obviously, there are other volcanoes that now and then produce more short-lived lava lakes. But the question was about persistent lava lakes of the Kilauea type, so let us stick to those.
A lava lake is a type of low-level eruption where the input of either heat or fresh material is hindering the lava to solidify, this is aided by the surface solidification of the lava that in turn acts as an insulating material hindering heat from escaping.
The solidified surface never creates a solid layer, instead it is reminiscent of disjointed ice-sheets drifting on a turbulent river, or like continents drifting on top of the less solid mantle. After a while these sheets get pulled down into the molten lava and melt.
This is roughly all that we know about lava lakes, I obviously condensed it a lot, but the gist is that this is the bulk of our knowledge that is true for all instances of lava lakes. None of this really helped me to answer Jesper’s question, so I had to sit and figure out more things about lava lakes.
Problem was just that as soon as I figured out something for lava lake volcanoes that are comparable to Grimsvötn, it did not fit Mount Erebus. A good fundamental thing must after all function for all instances observed, or your science is warped. In the end I literally discarded hundreds of ideas.
My favourite scientist is Einstein. Not because he came up with something incredibly convoluted and hard to grasp, instead I admire him for coming up with something that is so ridiculously simple that it encompasses almost everything. One single thing to rule them all, to misquote Tolkien.
It has been erroneously stated that only 100 people understands Einstein’s theories of Relativity. Nothing could be more wrong. In fact, the fundamental part is quite probably the single easiest scientific theory to understand. ‘What is observed will be different based upon your point of observation’. That is all of it, one sentence is needed to explain the fundamental part of the theories of relativity.
Yes, the mathematic proof behind it, and the effects down the line can be a bit hard to understand, but almost all parts of the theories of relativity can quite easily be explained by using common words. Testing the theory? Nothing could be simpler, all you need is a car, a friend, functioning eyes and an apple.
So, I discarded finding something complex, and went for something simple, the simpler the better. To be able to do this I went back to Eyeball mark 1 and watched hours of videos of bubbly lava lakes.
What I came up with are 3 observable facts that anyone that has watched lava lakes must also have seen. But, as where Newton just saw one effect of a falling apple, Einstein saw something very complex emerging from the falling apple under motion. In turn those 3 things gave me an idea of how to answer Jesper’s very tricky question.
Modes of convection
A lava lake can only be affected from 2 modes of convection. Either an open conduit is transferring large amounts of heat energy upward into the mass of lava in the lake, or lava is moving up through the conduit into the lake aiding to keep it in a molten state.
Both modes come with their distinct set of problems. For heat convection mode to work the conduit must be substantial, the reason for this is that rock (molten or otherwise) is a very good insulator. A narrow conduit would not be able to transfer enough energy upwards to keep a substantial lava lake like Halema’uma’u open.
Now, convection through lava injecting through a more normal conduit into the lava lake does not require a large conduit. But it comes with a massive problem that must be explained. If lava is entering the lake the level should be going up at a steady and observable rate, causing normal lava flows as the lake over-flowed.
We therefore must input an ad hoc solution here to explain why lava lakes does not have runoff lava rivers happily galumphing down the mountainsides in rivulets and happy little lavafalls. Let us assume that the excess lava is going down into the depth again due to having become cold and dense (for instance after having “frozen over” in the form of lava-sheets).
Problem is just that the conduit is busy pushing up warm fresh lava, and unless that conduit has a very odd topology, it is not possible for our cool lava to go down here. Instead we need a runoff conduit that is separate. Question is just why there is not warm lava coming up that way too?
Luckily for us this has been observed briefly during one of the Krafla Fires eruptions. During a smaller eruption two fissures opened up at the same time, one erupted lava, but the other one was dry. The lava from the first rapidly flowed into the other and disappeared.
If this had happened in a crater, or small caldera, and the eruption had continued, we could have gotten a lava lake with true lava convection.
Kilauea and Krafla both exist on top of rifting fissures, so it is not entirely impossible that two rift-conduits opened at Halema’uma’u, one from the magma reservoir, and one leading to somewhere. In the case of the Icelandic eruption the rift probably did not go into the magma chamber, so it would probably in the end have over-flowed.
But, in the case of Kilauea we have the potential that a rift opened towards Pu’u O’o and helped to feed that eruption. It does not explain other lava lakes where there is no sub-eruption going on.
This part requires further studies from young strapping scientists, and I will happily leave it to them. In our particular case, this is not where we will find the answer to Jesper’s question. Instead, let us discuss size and flowrate of ejecta.
The small thing about size
As you watch a video of a lava lake, or if you are looking at one live, you will be filled with a sense of awe and majesty over how big the phenomena are. One who was completely blown away was Mark Twain when he observed an old lake at Kilauea that covered a far larger part of the caldera than Halema’uma’u, it was probably one of the few moments in his life when even he had to struggle for words.
But what we are seeing is the effect of the eruption, and not what is actually coming up. A large eruption spanning hundreds of cubic metres would simply just overflow creating those happy rivulets and lavafalls as it fell down the mountain.
A monogenetic lava shield can only form if the flow rate is small enough, typically counted in the low tens of cubic metres per second or less, small flow is here building a large volume due to the long duration of the eruption.
It therefore gives that a lava lake eruption can’t have a higher outflow than a shield since it would create a lava flow or flood basalt. A flow in the tens of cubic metres would instead cause a monogenetic shield (unless of course the hypothetical return flow conduit is large). This leaves us with just a few cubic metres, and that is amply enough to keep the lava well above the point of solidification.
The Great Equilibrium Machine
The essential part that is a logical must, and is indeed observably so, is that a lava lake is a steady state eruption remaining at equilibrium throughout the eruption. This is also true for all known lava lakes.
Yes, the level of a lava lake will ebb and flow over the course of its existence, but it will ebb and flow around an equilibrium point. Now we are ready to start discussing our way to an answer of the question.
We now know that the eruptive rate is low and fairly constant, something that is made apparent from those volcanoes that are closest in comparison to Grimsvötn. Both Erta Ale, Kilauea and Ambrym, are large shield volcanoes.
They have been built up during numerous eruptions that individually are not that big but are numerous or have a long duration. Obviously, I am aware that Kilauea can do big eruptions too, but in regards of the lava lakes this is not important for the discussion.
This makes them prone to have eruptions small enough to produce an eruption at equilibrium between inbound energy and outbound energy. Or intruding lava and outgoing lava in case there is such a hypothetical thing (I do believe this is the case, but I can’t prove it).
They are also rift volcanoes, making them more prone to open two or more conduits in a small geographic area for the lava to circulate through.
Now let us instead look at Grimsvötn. It is a mantleplume volcano of prodigious size and power. It is also a rift volcano, but unlike the others the rifting is an inherent feature of global tectonism, that in turn is pulling the volcano in half at stable rate. The last part has a rather important effect on when it will be erupting.
For normal volcanoes you try to calculate how much pressure the lid of the roof of the magma chamber can withstand before an eruption will occur. At Grimsvötn the pertinent part is instead how much strain the roof can withstand before it is pulled apart.
As the lid is ripped apart a considerable over-pressure is released from the reservoir in the form of the eruption, and at the same time the pent-up local strain drops to zero, and as the over-pressure is gone the lips of the lid will weld shut.
In actuality it is obviously a combination of both intra-chamber pressure and tectonic strain that causes an eruption at Grimsvötn, but the strain part is not as evident at the other volcanoes, nor does it happen at the same freight-train geologic speed.
We normally say that Grimsvötn does not have eruptions below the VEI-3 mark. This is in a sense of it true, nothing below this size can erupt through the thick ice cover. Smaller eruptions would also be quenched by the ice and the water.
So far, we have though not seen any signal indicating that small abortive eruptions have occurred. We can also compare with other Icelandic central volcanoes. They also tend to have large eruptions with a time period in between them.
Icelandic volcanism, nor Grimsvötn does equilibrium. It is either all, or nothing. So, to specifically answer Jesper’s question, regardless if there is ice and water inside the three calderas of Grimsvötn, there is no chance that there will be a long-term eruption small enough to be at equilibrium.
Iceland has twice created false lava lakes in living memory, one during Holuhraun and the other during the Surtsey eruption. They where though not real lava lakes since they constantly over-flowed with lava due to the high eruptive rates.
As I reread this, I could feel how Albert would at this point be formulating a rather stern comment on what I wrote above about Einstein. I should therefore explain that I happily simplified things so much that I wilfully mixed together the two theories of relativity that Einstein wrote, and that I simplified things so much that it is impossible to gain any true understanding of the theories.
Obviously, Albert is correct in what he would probably have written. In my defence I can only say that I wanted to convey how a fundamental simple thing can affect everything. Mea Culpa!
114 thoughts on “Lava Lakes – The Great Equilibrium Machine”
Thank you Carl 🤟
This is really a great read…
The reason I even asked ( so Volcanocafe knows )
Is that Grimsvötn does appear to have the open conduits and constant magma inflow and molten system thats key for having lava lakes or shield building..
Thats why I got curious.
My question is answered
This article and your earlier words about it explains alot.
It makes sense that the Hotspot – Mid Ocean Ridge enviroment in Iceland prefers large fast eruptions where large dykes loose pressure quickly in fast lava eruptions and eruptive rates greatly exceed the supply.
In Iceland most of the magma is trapped underground as it must fill the gaps in the spreading.
In Iceland eruptive rates often exceeds supply enormously as this article says.
The spread in Iceland is also more than 10 times faster than Erta Ale and Nyiragongo, so more magma is trapped at depth in Iceland.
Still Grimsvötn is open conduited and molten and haves a massive supply: IF Grimsvötn does a long lived summit eruption: it rather becomes something like Surtsey or Holuhraun
Convecting lava lakes there in a tuya? = nope
Just a notice about lava lake circulation
Lava lakes circulate in the same conduit – magma column not in separate conduits
Halemaumau was a pipe 300 m wide
One side of that pipe the magma rised
The other side it sinked
Up and down in same magma column : )
Actually, that has never been proven Jesper, and it would take a quite astonishing conduit from a topological standpoint. Do note that I am not talking about the lava column (or pipe), I am talking about the conduit leading up to the column (pipe) that is the lake.
The sinking lava can’t go down any regular conduit as upgoing magma is coming through, the cold lava would just be reheated immediately and remain, and then we have a regular eruption since the lake would permanently overflow.
Here is the problem, we do not know what happens through the sides of the column, and we do not know what is happening at the bottom of the column. Only way to get to know that would be to do an archaeological style dig and remove all the rubble in the old lake down to where the column became became a conduit. A very dangerous and mammoth project indeed. Sadly it will never be done, even though it would aid volcanology immensely.
Very dangerous indeed! And hot too..
All that rubble been heated from 2008 to 2018 and probaly heat from 1810 to 1920 s lava lake too.
Then its that hot ( 70 c ) lake of watery acid to deal with too.
Huge spihons plumbing pumps woud need to drain it and the acidity woud eat thrugh the equipment mecanisms over time. Hot acid water.
The conduit itself is well pancaked in too
Once the rubble is removed its probaly so hot thats its hard to dig.
Too big and costly project
And it woud never be allowed in HVNP
Your commentary is excellent
Yea it woud heat up on the way down in Circulation
The lava lake of Kilauea has drained several times always revealing a cylinder shaped conduit as far as it went and with a width similar to the lake. Obviously it reaches a point where the walls start collapsing and bury it so you can’t see anymore. I am not sure when has it been observed the lowest but in May 2018 this video shows the lake 220 meters down:
All that space was carved open by magma in 10 years making a very wide conduit that perfectly allows up and down transport of magma at the same time. I don’t see any reason why the conduit should be narrower farther down, if anything I would assume it to be wider due to having been exposed to the magma chamber for a longer period of time.
Actually the lake must be much deeper in that video because apparently it had dropped 220 m by May 6 while the video is taken in May 9.
Correction to my comment again: the lava lake had dropped 220 m by May 6, the video was taken the evening of May 7, the lake stopped being visible in May 9.
I have to say that this is how I saw it. Basically a lava ‘water table’ whose pressure is maintained at a reasonably constant pressure. Its how that reservoir maintains such a constant pressure that is difficult to answer and may not be the same mechanism for all lakes.
Certainly they all seem to have hot material rising (often at one edge) and falling so the conduit will need to be wide enough to allow hot melt to rise on one side and cold to fall on the other without too much mixing. Mixing is the problem on the face of it.
I suspect an odd mechanism is working here possibly related to ’emptying corn bin’. This is a counter intuitive way a corn bin (actually a bin of any granular material) empties when there is a hole in the bottom. What actually happens is a very narrow ‘conduit’ forms through the granular material that flows (this may be only 150-200mm wide) linking the free surface at the top with the outlet hole at the bottom that contains ALL the moving material. The rest of the bin is static. This happens in bins from 1000+T to 30T and over 45m tall. The physics is quite obvious one you know it happens. I suspect this may be related. as the granules are effectively ‘very viscous’.
I’ll just chuck that in the pile.
I like your grain bin analogy 🙂 seems plausible to me
As a heart patient I think of the numerous Doppler sonograms I have had. Can’t something similar be used to analyze the fluid flows?
Jesper, I also call your attention to the fact that, for some strange reason, shield volcanism only occurs in some parts of Iceland:
– From Krivusik:to Langjokull: shield volcanism is relatively common,
– From Hekla to Bardarbunga: shield volcanism never seems to occur, only fissure eruptions.
– From Bardarbunga until Tjornes: shield volcanism is again common. But so are fissures.
The last region is where Holuhraun happened and this is why I was originally excited that Holuhraun was perhaps the beginning of a shield eruption (someone suggested it to be named Irpsitdyngja). Unfortunately I was wrong.
Why this happens?
I still don’t know, but I strongly suspect it is down to tectonic (rifting) orientation angle to the direction of plate movement.
This is an excellent read …
And of course, lava lakes are eyecandy
I seen the halemaumau one many times
But missed the highest levels in spring 2018 before it drained.
Vistors at Jaggar Overlook or specialy Nyiragongo hikers often plays a game when its dark and the glow is best: they each pick out an intresting shaped crustal slab, and they see how long their chosen plate surivive before being swallowed/ remelted by the inferno below.
The persons plate that surivives longest: that person gets rewarded by candy or some cash or beer
I remember the false lava lake at Holuhraun. It was spectacular but as Carl said, it overflowed at a large rate creating a huge and long lava river. Quite a sight!
I kind of grasped the same insight as you did, a lava lake requires a state of equilibrium of a slow steady influx and outflux (all within the lava lake and volcanic edifice)
I think there is a situation that could cause a temporary lava lake in Iceland, but that’s rare, which would be during a shield eruption, probably towards its end. But I can’t say that i am confident that this is even a possibility,
Lava lakes tend to form in shields. So that makes me wonder about it.
I estimated once that Iceland has a shield eruption about twice per millenia, so with the last one having been from the northwest side of Langjokull around 1000 AC, we are sort of waiting for the next one.
But Grimsvotn due to its very high influx is a extremely unlikely candidate for a lava lake.
It would have to be a volcano that would sustain a slow steady influx of high temp magma, where a state of equilibrium could be reached by luck. I could think of Hengill, in addition to Krafla, as well as Langjokull.
Seems likely. In terms of plumbing the monogenetic shields of Iceland could be comparable to the satellitic shields of Kilauea: Mauna Ulu, Pu’u’o’o, Kupaianaha… all these initially developed from a dike but soon grew a stable conduit with a lava lake, however much more unstable than the typical summit lava lake. For example Kupaianaha and Mauna Ulu completely crusted over and died, which is something I don’t recall ever happening to a summit lake which prefer to dissapear in collapses.
A crusting lake suggests lava inflow but no circulation. When the inflow decreases, the lake becomes stagnant. Agung is in that situation.
Agung is a pancake dome …
Top of a viscous blocky lava body.
Not a lava lake at all ..
That pancake dome only grew and did not convect at all.
Had it overflowed you woud get a normal blocky andesite flow.
Agung haves 1000 times more viscosity than even Erebus lava lake haves.
Agung is hard as rock too.. hard blocky surface
I do feel that for something to be called a lava lake it should be actively convecting or otherwise a lot of other eruption styles would fall into the lake category, like all silicic lava domes for example.
Carl: just another musing
Grimsvötn due to its very high influx of magma
And competely open conduits and shallow magma chamber: can it do a constant lava flow oooze?
It should be able to do a Surtsey phase in the caldera that builds into a Tuya formation or at least a long lived basaltic event. Imagine a Trölladyngja growing up in Grimsvötns caldera in a few decades
But maybe.. tectonics and pressure is at work again here only allowing short and violent fast eruptions … : )
Yes, just read my comment above. Shields never seem to occur near Grimsvotn.
But north of Bardarbunga they are relatively common. But not the exclusive mode of volcanism.
Yes thats true: Convecting lava lakes cannot happen in Grimsvötn
But Grimsvötn is open conduited and very hot and haves a very large magma supply.
Grimsvötn sounds like a volcano that should be ooozing lava all the time from a tuya thats grown out from a subglacial eruption.
Weird it does not do it.
But tectonics are probaly reason as Carl says
But what is plumbing behind eruptions of Grimsvotn? because it is not the same to be fed from a dike, from a ring fault where the caldera opens like a trapdoor or a pipe shaped conduit. The earlier 2 tend to close (though not always) so are not very good at holding lava lakes.
All of the eruptions at Grimsvötn has either been dykes or ringfault eruptions.
Long lived, forget that one. For the reasons in my article up above.
Unrelated to this: I just have been noticing how seismic activity in Reykjanes peninsula in Iceland seems to have increased in recent months. This follows a pattern observed in whole Iceland, linked to increased plume activity. However Reykjanes was already seismic before, so any increase in activity could easily lead to an eruption there. Something to keep an eye on.
Personally I am betting that Reykjanes will have an eruption sometime in the next decade or so.
The volcano erupts about once a century at least…
Reykjanes is the small volcano just outside the tip of Reykjanes Peninsula, I think you are pondering either Svartsengi that is the next volcano going towards the centre of Iceland. Neither of those two erupt often. Perhaps not even once per millenium.
If you mean the next further out on the Reykjanes Ridge, that would be the Geirfuglasker Volcanic Complex, and that erupts roughly once every century.
Sorry talking alot today
But whats the lava threat to Reykjavik?
There are many pahoehoe flows outside and inside parts of that city.
Whats the chance of 1990 s kalapana – Nordic version on steroids?
Of course I dont want lava to invade Reykjavik
Carl and Irpsit = how lava safe is Reykjavik?
Unless we get a Raudholar event the risk is fairly small. The Reykjavik Raudholar cones does not exist any longer, someone carted it off as building material.
The risk is not zero percent, but it is let us say 1:4000 at any given year. And since the flows are small, and we are talking about Icelanders, they will probably just draw some very long pipes and hose the shit out of the flow stopping it. Like they did at Heimaey.
Thanks Carl excellent discussion
Heimeay was an Aa flow and most of it flowed into the bay…
Lava haves extremely low heat conductivity so, you only cools the surface.. its a great insulator.
This is why lava can flow so freely and smoothly underwater: rock insulates. In Galapagos there are submarine pahoehoe – tube flows that are 20 km long at great depths. Rock insulates.
Are you really soure it was the water bombing of Eldfell that stopped the lava flow?
In my own opinion the lava made no direct assult, more than torching outer edges of the town.
Had the vent channel been directed amied directly at Heimeay
The results despite water attack coud be very diffrent …
Have in mind in Kalapana
They failed cooling very thin fluid pahoehoe flows with hoses
Many home owners sprayed tons of water a day on small breakouts
The lavas crust stopped the water from chilling the interior
They failed when the lava front was only passing by and not directly at them.
I knows Reykjavik can mobilise an army against a lava flow.
But its likley too that cooling a large well insulated pahoehoe flow in the future will probaly end in failure.
Bombing / digging open lava tubes like they have done on Etna are more useful, that stops the lava from insulating and force it to take New paths
A lovely, thought-provoking article.
What can’t help is that a lava lake is very unlikely to simply stall and solidify in place, allowing possible study of flow and counter-flow within volcanic plug exposed by erosion. At least, if a pattern develops of volcanic ‘types’ that support lava lakes, there’s more chance of spotting such features…
Tangentially, your patient lake-watching reminded me of lonnng hours glumly guarding multi-litre organic syntheses ‘going tholine’ beneath their stacked reflux condensers, steam-distilled ‘Essential Oil’ analyses accumulate drop-wise, and 6-racks of Soxhlet extractions play, ‘I’ll siphon next’…
I’ve taken a copy of that geothermal lake pic as it may help with a story I’m writing.
It might actually have happened at least once that a lava lake solidified.
The reason that I suspect that is the way that Kilauea just became a nested caldera.
Most calderas block from the bottom up, like for instance Askja, in other words that the unsupported roof start to fail on the inner side and sequentially works its way upwards, like in a deep mine.
But, here instead we got sequential slab-caving instead of blocking. And that is when top to bottom blocks shave off from the initial hole outwards.
Normally that only happens if the area above a mine is thin, typically in a mine it is 50 metres, but here the cavity would be far larger, so something like 200 to 400 metres would be possible.
So, it is possible that what happened was that a previous old larger lake had indeed started to solidify from the top downwards, but with the bottom half being either still molten, or remelted mush as the newer lakes formed.
It is an intriguing idea that I have been playing with, it could to all points and purposes even be the large lake that Mark Twain saw.
I remember that discussion about the giant lava lake here some time ago, however the commenter that posted that was confused, there has not been such inmense lava lake that we know off.
To clear out things the story goes like this: William Ellis visited Kilauea in 1823 so it was the first westerner that climbed the volcano (he and his companions) he arrived at a very interesting time when a SWRZ eruption had recently taken place and all the natives were talking about it. He saw the smoking fractures between the eruption site and the summit and when he got to the caldera he saw a nested caldera and some lava lakes that were probably rootless. William Ellis came out with the idea that the nested caldera had been a big lava lake that had drained down the fractures to the flank eruption, which is amazingly spot on! but wrong in the part of the large lake, what he was gazing at was a caldera collapse. But some people took it as a fact inspiring the myth of the giant lava lake…
It’s been said that the North Crater at Tongariro with its kilometre wide perfectly flat surface is a solidified lava lake. Don’t necessarily buy the idea myself, it’s not the right environment (subduction, andesite)
If it is made up of andesite then maybe it is more of a dome like Agung, though depending on your definition it might be considered a lake but it would certainly look very diferent from a proper lava lake like Nyragongo’s.
I think that lava lakes are limited in size by the capacity of the volcano or magma chamber that feeds it, so it depends but a proper lava lake probably can’t get much more bigger than those of Nyragongo or Kilauea, though the lava lake of Kilauea was still growing in 2018 so it hadn’t reached its full size yet. This is though mostly an idea in progress from reding about hawaiian lava lakes.
Rootless lakes can grow much larger, these are not true lakes but rather form when lava is erupted rapidly into a depressed area, you may prefer Albert’s term lava cenote. I do have seen through Google Earth one of these that is 5×3 km in Alayta volcano, Afar, under ideal conditions they probably can get far larger. It must be quite an spectacle, but a rare and short-lived one, the surface of the lake only remains molten as long as lava is still being added into it at a high rate, as the eruption wanes it will crust over very quickly
Siberian Traps and Opening of the Atlantic
probaly formed rootless ponded lava seas many 100 s of km across
In really extreme situations…
In opening of some of the really large flows ( 10 000 km3 per flow )
You gets fissues many 100 s of kilometers long and lava fountains roars kilometers high along them!.
Souch eruptions forms hellish lava seas and sheets of Aa lava as large as entire states.
Holuhraun and Laki gas pollution are very miniscule in comparison
Siberian Traps must have been an awesome sight
Many 1000 after 1000 s of times bigger than anything I seen in Hawaii.
I wants to travel back in time 251 million years ago and just see the size of the lava rivers, the size of the lava fountains…
It must have been an incredibe sight!
No one knows how Siberian Traps looked like in action
But it was indeed huge
Mount Erebus is a very strange lava lake!
This is the ONLY “high viscosity” lava lake in the world
It convects and degas just ike its more fluid basaltic counterparts.
But Mount Erebus haves a viscosity thats around 100 times higher than Kilauea.
Erebus is so viscous it degas by gas burps, rather than spattering and sloshing.
Erebus is a Phonolite: basicaly an extremely alkaline version of andesite in silica content.
Mount erebus is a weak hotspot under a slow spreading continetal rift.
The partial melting is small and thats why Erebus is alkaline.
Phonolitic magmas usualy dont behave like this
Erebus is probaly very hot and quite fluid for being a Phonolite.
Most phonolites are acossiated with explosive tephra eruptions.
I seen that Nyiragongo haves many more crustal plates than example Erta Ale.
Why is it like that?
Nyiragongos lava lake is way bigger and convection is probaly much faster in Nyiragongo : )
Thats why Nyiragongo is more broken up lake crust.
Is my opinion here right Carl?
And once again the reason I even asked
Is that Grimsvötn does appear to have the open conduits and constant magma inflow and
molten system thats key for having shield building.
Thats why I got curious.
Grimsvötn is the only volcano in Iceland thats this molten and open conduited in magma system as whole.
Grimsvötn sometimes feels like an Icey Kilauea that cannot behave kilauean.
This is an excellent article.
Jesper, its a good question, that leads to the question I asked above: why is shield volcanism in Iceland so abundant in specific regions and absent from others. What factors in tectonics are causing that? Sincerely I do not know, but I suspect it’s connected to the angle between rifting and tectonic movement. Maybe Carl can write an article on this topic.
Grimsvotn is not an icey Kilauea. Iceland and Hawaii seem to behave differently, independently from Iceland having ice caps on it. Hawaii has a movable hotspot. Iceland is apparently fixed (or at least it does not show a string of islands like Hawaii does). Hawaii is in the middle of a plate. Iceland sits at the rifting between two plates. These are very big differences.
Hawaii is a fixed intraplate hot plume under a seafloor that moves west
Iceland is a plume thats emerged under a divergent boundary: hotspot under a spreading ridge.
So yes the geology is very diffrent between the two. And the volcanoes work diffirently too.
Its Grimsvötns open conduits, hot fresh basaltic magmas and massive supply, that makes me call it an Arctic Kilauea
Yes, it is an interesting question. You get a shield when the lava cools relatively quickly when flowing away, so that it stops flowing at some distance. The cooling rate depends on the flow rate: higher flow rate means thicker flows which cool slower, so get further. As flow rate decreases during an eruption, it gets less far and therefore builds up. Viscosity is important: lower viscosity means easier flow and therefore it gets further. A continuous flow rate helps, as it allows for lava rivers to develop, as happened in Puna. Varied the rate, and such rivers get clogged. Topography will make a difference: a flat country side makes shields easier, a sloping one especially with river valleys makes the lava flow. I am not sure how much this helps, but between Hekla and Vatnajokull the flows are relatively steep, and the eruptions here seem to have high flow rates.
It is really intriguing, another group of volcanoes that has fluid hot basaltic magmas and erupts very often but yet never seem to do lava lakes are the volcanoes of Galapagos. What does Galapagos and Iceland have in common? high supply, large magma chambers, ring fault eruptions. But there is also the major difference that Galapagos is not on the rift while Iceland is..
This problem also got me thinking about Piton de la Fournaise which didn’t seem to do lava lakes either. An intraplate volcano with radial, ring fault eruptions and weak hawaiian-like rift zones. Apparently Piton de la Fournaise actually does lava lakes quite often, or at least it used to before 1900, never again afterwards. So now there is a second question why does a volcano stop forming lava lakes all of a sudden?
The answer might be in understanding how a lava lake forms but personally I don’t even know how the Halema’uma’u lava lake got there in 2008. You can’t blame it on pressure because the summit was deflating, short fissure eruptions at the summit are very common but follow a particular dike swarm (part of the volcanic SWRZ) and the lava lake grew away from it and while the Halema’uma’u lava lake was nearly always present before 1924 and usually formed again after collapses it took nearly a century to return in 2008.
Grimsvotn cannot have a fully open conduit. We see the internal pressure in Grimsvotn building up over time as shown by the earthquakes. Open, magma-filled conduits show no earthquakes. The path between the shallow magma chamber and the surface is a closed one. Carl thinks it is pushed open when the internal pressure exceeds some critical value.
The conduits from melting region up to the upper magma chambers are probaly almost competely open …
No deep earthquakes in Grimsvötn
Its the roof in the upper magma chamber that have no conduit up.
As the upper magma chamber refill it expands and stresses the bedrock causing shallow earthquakes
What is the definition of open conduit being used here? A volcano like Kilauea with conduits to the surface (Halema’uma’u and Pu’u’o’o before 2018) can still have earthquakes and deep earthquakes (Pahala).
The deep conduit is most likely open as Jesper says, we see this from a marked lack of deep earthquakes. Most of the upper earthquakes are associated with expansion of the magma reservoir in under the southern caldera wall roughly where the increase in geothermal heat is.
The deep one is, I think. But the conduit to the surface is not.
During the onset of a volcanic eruption, there can be a period of an hour or so where the earthquakes cease but before the eruption has started. That is probably when the conduit is full.
I’ll now wait for someone to point out that Hekla operates just opposite to this.
There is No conduit to the surface in Grimsvötns caldera roof ..
I badely wants one to form
Since the magma chamber is so shallow too.
Just wait. I give it 15 months before the conduit opens. Explosively.
“I’ll now wait for someone to point out that Hekla operates just opposite to this.”
Probably because Hekla isn’t really a stratovolcano yet. It’s still an overgrown fissure cone-row.
The magma thats filling Grimsvötn these days are probaly like the hot basaltic magma that feed Holuhraun.
Grimsvötn is probaly even hotter as 2011 s materials where very mafic and thoelitic and little crystals in it
The upper magma chamber in Grimsvötn is probaly close to 1200 C these days
The magma supply to Grimsvötn is very large
Thats another reason I calls it an Icey Kilauea…
It also pretty much haves the same hot Thoeltic Basaltic magma.
The magma output is about 0.005 km3/yr . This is a typical rate for volcanoes. What distinguishes Grimsvotn is the ease with which it is ejected. Of course, it does not count the magma that stays below and builds the underground volcano. Effectively, the amount that fills ni the rift.
Carl says a potential 0,5 km3 yearly supply is this really true?
I guess alot of magma in Grimsvotn ends up in passive rifting and never comes up.
Yep. This is what comes out. What goes in may be much more.
Grimsvotn has produced 50km3 since the ice age, quite a lot of which was Laki. But you can’t really compare rifting volcanism with non-rifting ones because so much is used below ground to accommodate the rift. Hawai’i does not have that and so has a much higher ratio of magma eruption over magma production.
Yup thats true…
Only 10% whats intruded in Iceland erupts… because of the spreading.
If the spreading was faster .. even less % woud erupt.
Its hard to imagine that EPR is spreading 18 times faster than Iceland!
It have produced much more
You forgets all the small caldera eruptions and the Sakursunarvatn Tephras
Small eruptions make little or no difference. Only the big ones really count. I have used the ‘accepted’ number where eruptions are known to be from Grimsvotn. Note that some people argue that Laki wasn’t from Grimsvotn, in which case my number needs to be reduced down to 0.003.
If 2011, 2004, 1998, 1996 and the others in 1900 s are normal in whole holocene era of activity..
We ends up with roughly 200 km3 of materials produced in 12 000 years .. probaly more
Carl Rhenberg what do you say about this?
2011 produced 0.02 km3 DRE. The others are typically ten times smaller. Assuming one eruption per decade of this size and one 2011-sized eruption per century, gives 0,04 km3 per century. Per 12,000 years that makes 5 km3. Add in two laki-sized events, and you get to 50 km3. Not 200.
Hi Albert, I must sharply disagree.
I think your eruptive volumes estimates are far too low.
Grimsvotn erupted about 0.7km3 tephra (perhaps 0.2 km3 DRE) in 2011
Just travel to Iceland back in 2011 and you would be impressed by the volume of deposited ash, far above the levels of Eyjafjallajokull.
And the Grimsvotn eruption of 1998 erupted about 0.07km3
It was a very small eruption, for Grimsvotn standards.
Your estimate of 5km3 per 12.000 years is also too low.
The Saksunarvatn eruptions, in early Holocene, some 10.200 years ago, were at least 10km3 (at least is an understatement), so those alone are above your 5km3. Probably they were the product of multiple eruptions within a short period of time, totaling something like 450km3 http://adsabs.harvard.edu/abs/2014AGUFM.V24B..04T
So, since the ice age, we might have seen Grimsvotn eruption more than 500km3 (450km3 in Saksunarvatn, 50km3 in two confirmed Laki events, and probably at least 10km3 for all other eruptions)
That gives a rate of 0.05km3/year of erupted material, which totally makes sense to me, considering what I know of Icelandic volcanoes.
But in doubt maybe best to ask Icelandic scientists.
All of my references above are at least partly Icelandic.
Yes, the 0.02km3 should have been 0.2km3. Should have checked my sources better! That makes it closer to 0.5km3 per century output, or 50km3 explosive DRE since the ice age. Add in Laki times two and you get some 100 km3, not 50. Laki is still quite dominant which is why the number doesn’t change by that much! Estimates in the literature for Saksunarvatn vary from ~10 km3 to 30 km3.
But as you stated Albert, and correctly, most of magma actually becomes involved in filling the space of the continuous rifting of Iceland.
The magma output is probably best estimated about 0.05km3/year
Whilst the total magma influx is about 0.5km3/year, just as estimated by Carl.
All sources say Grimsvötn produced 700 million cubic meters in 2011
Alberts numbers are wrong
Or its myself thats knows too little
Yes Jesper, I confirm your numbers. Grimsvotn erupted 0.7km3 tephra in 2011 (700 million cubic meters). In DRE that is probably around 0.2km3.
Both 2011 and 1996 produced
700 million cubic meters each
Thats 1400 million cubic meters when two are combined about same size as Holuhraun
Yes, both 1996 and 2011 were about 0.7km3 each. So in fact, their combined total is about the same as Holuhraun, at 1.5km3.
Yet to my eyes, from an Icelandic perspective, it looks like Holuhraun was considerably larger. But I trust the scientific figures.
Some Icelandic explosive eruptions from Katla can be above 1km3.
Proper flood basalts like Laki or Veidivotn or Edlgja, are above 10km3, so one can only imagine what they look like.
Skaftareldahraun and Eldgja where of course much much bigger and faster than Holuhraun
But I dont know if they can be called Flood Basalts…
maybe mini flood basalts?
The real monsters
A single lava flow unit from Siberian Traps can be bigger than an European country and be over 10 meters thick.
Think 800 Lakis volume lava flow or even much more for the really big ones
The real severe LIP events
Are in – comparabely larger than Laki ever was
Whats the temperature of Grimsvötns upper magma chambers now?
2011 s materials where very fresh and primtive and thoelitic.
Probably something close to 1200 C ?
Maybe around 1190 C as there are some small crystals.
The quick cooling in the glacial-pheratomagmatism preserves the compostion of the 2011 s materials very well
Laki,Veidivotn or Edlgja are absoutley nothing compared to the huge prehistoric trap flood basalts….
Laki maybe a mini flood basalt?
Some induvidual flows from Siberian Traps and Central Atlantic Magmatic Province where the size of whole European Countries and over 10 meters thick, and erupted from fissures that coud be
many 100 s of kilometers long.
The Whin Sill that covers most of northen UK, shows just how enormously huge these Flood Basalts can be in plumbing system.
And some single dykes in Mackenzie giant dike swarm can be followed for more than 1000 kilometers: Imagne when souch events break the crust.
Imagine curtains of lava fountains that rise Kilometers high along fissures that coud be 400 kilometers long.
Humans have never seen a real flood basalt yet.
The most likley place for the next one, coud be the African Superplume.
“Some Icelandic explosive eruptions from Katla can be above 1km3.”
Think SILK. (Silicic Katla tephra) found all over different strata sites in Europe.
I have a query for the experts. To what extent does heat flow from the release of high temperature volatiles influence whether or not a lava lake forms; that is, instead of requiring a steady inflow of fresh hot magma (which requires all sorts of complicated explanations of where the cooled material goes after exposure to the atmosphere) you have a minimal addition of fresh magma, with enough heat being added to the system to keep the circulation going. Just a thought -inspired by that classic video of Ambrym’s Marum lava lake, seething away like an enormous pan of red-hot porridge on the boil
You run into a heat capacity problem. Gasses have low heat capacity, rocks have a high one. So gasses can’t easily heat rock, while rock can very well het gas. It is why your fan oven take so long to heat food.
Some seismic smalltalk under Hekla….
This is significant. This means an eruption could likely start in the next few hours.
I say it could, not that it will.
When it starts, it will resemble this. But the quakes would eventually pick up up to a handful M2 just in the hour before the eruption. But as we learnt in 2013, there is also the possibility of similar run-ups running short of an eruption with only a couple M2 earthquakes involved.
The ultimate signal is also a change in borehole strain at Burfell. I haven’t look at that yet.
Good to follow Hekla earthquakes tonight. The risk for an eruption is increased. At least for now.
Regarding Hekla increased seismicity: does anyone know the link to the borehole strain measurements at Burfell?
I don’t seem to be able to access that data….
I just had a look at the borehole strain. So far nothing unusual, so I don’t think an eruption is likely yet,
Only until the borehole strain starts to deviate from the normal, I would say an eruption is likely to 95%. This usually happens as a second significant quake hits Hekla, which hasn’t happened. So far we only had a M1.5 and a M1.2.
At the moment the risk for an eruption is there, slightly above background. Until more quakes happen.
You can find the graphs here:
I am also looking at these quakes with great interest, 10 years ago that would be a clear sign of a pre-eruptive sequence.
Now the sensor equipment is much more sensitive, so it might just be another sign of increasing pressure at the moment.
But certainly worth watching… and I‘m happy that she is not as quiet as it seemed in the past months.
Another low magnitude episode after midnight but no dramatic borehole strain or tremor as I can see.
In a short RÚV news article, Kristín Jónsdóttir from IMO has this to say about the current activity:
Automatic translation from Icelandic:
“Kristín Jónsdóttir, head of geothermal at the Icelandic Meteorological Office, says there is some instability there, which experts are not very concerned about, as it stands. The sensitivity of the meter network around Hekla has increased recently and now you can see much smaller and more earthquakes than before. This is an important step in monitoring Hekla and can hopefully extend the response time that was short in recent eruptions. Last erupted in Hekla in 2000.”
I would agree that this is not worrying. There is no signal on the strain measurements. However, I dont see the increases sensitivity as affecting this. The two initial earthquakes would have been detected in the past as well.
The longer Hekla stays quiet: the more evolved and viscous and explosive the magmas will get. 1970, 1980, 1981 1991 and 2000 where time of frequent eruptions and quite fresh magmas towards 2000 it became almost pure “cold” basaltic.
Now 20 years later its probaly not enough time to evolve the magma in upper parts of Hekla? Dirk S will Heklas next eruption be basaltic andesite? or andesite again?
Or is the time simply too short?
Dunno, but I have always wanted to hear Carl elaborate on the weirdness of Hekla’s geochemistry. From what I understand, it’s not quite what should be expected of it’s location.
A couple of years ago Carl had me do a look at some odd GPS data around Hekla. from what I could see, it appears as if a “lump” of magma drifted South by Southeast away from the edifice towards a valley and off to the Northeast up towards the normal rift trend. What that was all about I haven’t a clue.
My take on the occasional odd chemistry is that a left over ancient plate shard from the subduction zones of the ancient Iapetus or Ægir oceans closing (Caledonian orogeny) is contributing to Hekla’s chemical signature. (I also think this is one of the reasons that Iceland’s crust is so thick… essentially a plate fragment sandwich, but the “strange” sort of subduction zone chemistry doesn’t show up elsewhere.)
Warning; I an NOT a geologist. Your mileage may vary. Objects in Mirror may be closer than they appear.
Note: I also don’t have ready access to historical Hekla geochemistries, this is based off of a mention by Carl a few years ago about Hekla’s weirdness.
If there’s one thing which I learnt from Carl’s articles, it is that Hekla is a complex beast and more or less unpredictable.
The unique geological setting of Hekla results in a complex mixture of magma, and a part of it seems to be unique for Hekla itself.
But I tend to agree with Jesper, a longer time interval between the eruptions might increase the power of the initial explosion.
I like Hekla, but we have to keep in mind that it is a dangerous volcano.
Part of that mat be settling. Hekla is very young and the crust hasn’t adjusted to its weight yet. So the immediate are is sinking while more distant regions are being pushed up.
Heklas Andesites and Ryholites are the result of magmatic diffrentiation and nothing else at all
Hekla steals the Andesites and Rhyolites from the Cascades! That is where they come from! And that is why the Cascades are so boringly quiet right now… ;-D
Why Hekla is sometimes andesitic, dacitic and ryholite is very simple
Its simply old basaltic magma that been sitting undeground and cooled and evolved into more sillica rich compositions.
Same things happens in kilaueas rift zones! There is small pockets of evolved Dacite in Puna.
Heklas andesites are result of magmatic evolution / diffrentiation
Seems that Hekla patterns might have changed again.
Hekla eruptions were sparse in the first millenia, and very big. VEI5 or VEI6. In between Hekla was dormant for many centuries.
So when the first historical eruption happened in 1104 it was huge and devastating, as the mountain was not thought to be active back then. The 1104 eruption was as large as many pre-historical eruptions.
Following this large eruption, the pattern changed, for some unknown reason. Eruptions occurred almost always twice a century and they were either moderate VEI4 and at times devastating eruptions, small VEI5 ones.
Around 200 years ago, Hekla was dormant for a longer period, around 100+ years, and this was interrupted by a large eruption in 1947, again another one but by far not as big as the 1104 one.
Following a 20 year delay after that big eruption, Hekla erupted always every 10ish years, with small VEI3 eruptions, still with large lava fields forming.
I can speculate one main reason for the change of eruptive pattern in Hekla:
That large tectonic events in south Iceland directly affect Hekla plumbing and therefore its eruptive pattern.
This would fit well with the concept from Carl that Hekla erupts when the mountain literally rips apart (strained by tectonic forces) and magma erupts.
The pattern changed first, during the eruption of 1104 and thereafter. Hekla erupted not every few centuries or millennia, but start erupting around every 50 years.
What happened? I can think of one huge event that might have affected local tectonics, and that was the large Edlgja eruption in 934. But this is just a wild guess.
The pattern changed also in 1947. Hekla shifted from eruptions every 50ish years to every 10ish years. I can’t really see what might have happened, but interestingly following this, we have seen unusual eruptions in south Iceland: first two from the Westman Islands, and then the large eruption from Eyjafjallajokull.
Since 2000 (last Hekla eruption), a few other large events might have affected Hekla again:
– The 2000 South Iceland earthquakes
– The 2010s hotspot maxima, with major tectonic readjustements in Iceland, like Holuhraun
These are just very wild guesses, so please take these theories with a grain of salt (or better even, with a grain of ash)
Hekla doesn’t do patterns very well. It is too young. I would agree that the 939 Eldgja (not 934: that date has been updated) eruption may have had an impact, although it is not easy to see how that would have worked. The main process may be the conduit, though. When it erupts often, this conduit remains hot and easily opened again (and without earthquake activity). When it has time to cool, it stiffens and hardens and more pressure is needed before it is forced open (presumably with earthquakes). So a small change in magma supply rate might push it from mode to another. (The lack of earthquakes is a recent effect. Older reports do mention earthquakes before an eruption.)
The state of the transform fault in south Iceland may also play a role. I am not sure how often that releases its stress but it isn;t very often.
I have read a few papers about the magma composition of Hekla, but it’s some time ago.
You are right, basically it is a different degree of crystallization which causes Hekla to erupt the different magma types.
But Hekla is somewhat unique in a sense that due to the localization of Hekla there are many pockets or layers of magma with a different degree of differentiation stored underneath the edifice. It is more or less a multi-level-building with a different magma stored in each level.
However, the plumbing system of Hekla is very complex and not fully understood, if I recall correctly. The higher eruption frequencies in the past 50 years indicate a well established plumbing system with frequent instrusions of fresh magma, But this has also been observed in the past, followed by a long period of inactivity. And this indicates that the plumbing system is rearranged every now and then.
Hmmm whats the temperature of Grimsvötns upper magma chambers now?
2011 s materials where very fresh and primtive and thoelitic.
Probably something close to 1200 C ?
Maybe around 1190 C as there are some small crystals.
The quick cooling in the glacial-pheratomagmatism preserves the compostion of the 2011 s materials very well.
Irpsit and my response overlapped – we both noted the irrregular eruption intervalls. 😉
Some more shaking along Hekla. Is she really gearing up?
Vedur EQ map is not working… at least for me.
Rumor says they are dealing with some in house issues right now.
Using this instead: http://hraun.vedur.is/ja/drumplot/
E few quakes more and Hekla will break her monthly record since last eruption.
Hahahah on my 24 th Birthday in late october…
I wants Siberian Traps 2.0
I wants nothing else than a huge LIP event.
I wants to see fissures thats 500 km long
with many kilometer high lava fountains all along them…
When the next severe LIP happens all my dreams will come true.
Random geological forces: give me the hell flood on my birthday.
LOL I should stop wanting that
bad thoughts, bad thoughts, bad thoughts!
So, we’ll know who to blame if that happens then?
I wants to find that huge .. red button in Siberia
”press to erupt”
I woud press it hard for soure
I think you missed it. By about 250 million years.
The most scary thing of Late Permian woud be the Gorgonopsian! 😧😦🤐
A time machine visit there woud mean gearing up in armed power suits so these predators cannot chew with leisure..
A Gorgonopsian is much much more scary than a Lion since its more primitive and probaly more agressive.
Im happy they are extinct
New USGS Video: Water appears in Halemaʻumaʻu – Kīlauea Volcano
USGS Hawaiian Volcano Observatory scientists Matt Patrick and Jim Kauahikaua talk about the water that appeared at the bottom of Halemaʻumaʻu, a crater at the summit of Kīlauea Volcano, in July 2019 and continues to rise today. They address why it appeared, how it’s monitored, and its potential hazards.
See if it embeds this time
Hazard? That’s easy. Don’t fall in. It probably is quite similar to battery acid. As for future eruptions… it adds a phreatomagmatic threat. (Highly energetic)
There is also a good chance that future ascending magma will bake out the water before it reaches the crater.
Think “Kelud.” The subsequent violent eruption was due to the magma dome being overwhelmed by the pressure. The lake was pretty much evaporated by that time.
I think this can only end up with explosive eruptions, mostly because there is plenty of geologic evidence indicating that after the most important recent collapses of Kilauea a series of explosive eruptions have followed, it had long been suspected a lake of water was behind those explosive eruptions (accretionary lapilli in the ash, wet muddy ash with human footprints, the fact that the caldera was known to be deep in all those instances…).
And not to mention the fight between Pele and Kamapua’a that while the kupuna seem to be unaware of, it does mention water filling the caldera and then a shower of stones and lightning. The original legend has probably been lost, it was briefly mentioned by William Ellis in his journal (1823) later versions of the same myth are different.
Now we’ve got the crater lake, yet HVO seems to be downplaying the situation…
Un… farking, real. The FAA has a phrase for pilots like this when they screw up. “Controlled Decent into ground”
Yeah, I used to fly in this manner…. IN A GAME. But that took hours of eating trees and lamp posts. In real-life you don’t typically get a respawn.
New post is up. What’s in a name, when the name is that of a fish? Lurking can explains
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