Hunga Tonga and The Supercriticality Event

The eruption at 14th of January. Picture borrowed from

As the numbers for the Hunga Tonga eruption continues to come in it is becoming ever clearer that something truly momentous happened, something not seen or heard in 139 years.

With a columnar height of 55 kilometres, an explosive pressure wave travelling several laps around the planet, forming a medium sized deadly tsunami, gouging out a few cubic kilometres of rock, ash and silt, and so on and so forth it was to all points and purposes quite something.

Problem is that when we compare this eruption to a more common caldera forming event like for instance Pinatubo, we do not get the numbers to ad up. With such an enormous eruption column we should see very high amounts of SO2, and we should see a lot more erupted material.

The explosion does not seem to add up to the eruption. We need to figure out how such a comparatively small eruption could create such an over-sized explosion.

Judging from early satellite pictures we can estimate the eruption to have been between a mid-sized VEI-5, up to a miniscule VEI-6. So, we are back to 1991 and between Cerro Hudson and Pinatubo. So, the eruption is only small if we compare it to the explosion itself, in any other way it is the largest eruption in 31 years.

As explosions go it was the largest explosion witnessed by humans. Now remember that we are talking about the “boom” and not the eruption, humanity have witnessed quite a few larger eruptions.

Prior to Hunga Tonga the second largest explosion witnessed by humans was Krakatau in 1883, it has been estimated to have been between 20 and 30 megatons of TNT-equivalent.

It took the machinations of Beria, the insanity of Stalin, and the bizarre genius of Sakharov, but it in the early morning of the 30th of October of 1961 an enhanced Sluika with the project number AN602 was detonated with a yield of 50 megaton of TNT-equivalent.

The world named it the Tsar Bomba, and humanity for a brief moment in time grew a brain and stopped that particular direction of the atomic race.

Problem is that Nature is not that easily out staged. It was at that time busily priming a small non-descript volcanic caldera in the Kingdom of Tonga, named after the two small and equally non-descript caldera-rim islands, Hunga Tonga and Hunga Ha’apai.

After a bit of ever more impressive volcanic activity Nature was ready for the main show, and on the 15th of January it was showtime. Judging from audio tapes the main eruption was best counted in seconds, and in those few seconds Nature delivered an explosion in the range of 55 to 60 megatons of TNT-equivalent.

Incidentally, as I was writing this article the agency tasked with judging sizes of Nuclear Explosions just issued their calculations. It turns out I was spot on with my number of 55 to 60 megatons of TNT-equivalent. Just to be clear, I calculated this number on the 16th using barometric pressure readings, having confirmation of not being a “loon” is though always nice. Insert your favourite personal snicker sound here…

All we are left with are two miniscule remnants of the original islands, a gouged-out caldera, and a load of questions.

I will here try to answer two of them, and they are intimately inter-connected. Where did the SO2 go? And, what in the name of heck caused the explosion?


The missing SO2

The SO2 dispersion cloud from Hunga Tonga. Image borrowed from Newstalk.

This part is fairly easy to answer, and it has a profound effect on the second question. SO2 is a volcanic gas emitted from volcanoes together with fresh lava. Old lava contains comparatively little SO2 since almost all of it is transformed into all sorts of organic and non-organic sulphuric compounds, and those do not readily transform back into SO2 if lofted skywards.

We know that during the explosion a bulk portion of the bottom of the caldera decided to go and watch the movie The Adventures of Priscilla, Queen of the Desert at location in Australia.

In other words, it was a mixture of volcanic rock, old ash, old tephra, old pumice, and silt, that was exploded outwards, and that very little of fresh material was exploded skywards. And with little fresh material we get little SO2.


The Eruption Purist Interlude

There is a particular brand of stupid that now will start to argue that it was then a very small eruption, a VEI-2 or a VEI-3.

They will now categorically claim that the definition of every conceivable eruption scale is the amount of fresh material erupted.

I invite them to go and stand at a VEI-3 safe distance from the next Krakatau style eruption. Arguing pointless semantics is not your friend around volcanoes if you wish to remain alive.

The rest of us are probably happy with the total amount of ejecta, and the implications that have on life expectancy. So, let us move on to the main question. At least I am positively wet from anticipation by now.


The Other Volcanic Fluid

Water in two forms I do not like. Ice and cold water. This is the Thwaite Glacier, aka. the Doomsday Glacier, it will be quite gone in 5 years time. Image borrowed from the Rolling Stone Magazine.

Most of our readers are familiar with the term “volcanic fluids”, but I should explain it the same. It is a term often used by volcanologists as they describe any unknown fluid inside of a volcano. Often in relation to inflation or deflation of various sections of very large calderas.

The fluid could be magma, water, molten sulphur, and so on. Basically, anything that is fluid enough to move around causing changes in a volcano, either by intrusion, or by being pressured into a new area.

In large dying calderas like Yellowstone this would be counted in as little as an inch or two over a year. But, in other livelier calderas it could be counted in metres in just a day or two. The latter holds true for calderas like Amatitlán, Campi Flegrei, and Tondano, just to name a few.

Typically, both laypeople and volcanologists are way more interested in the potential for magma movement, after all, that is what we perceive as the dangerous version of volcanic fluids. Turns out we may have been quite wrong about this.

Up until now the only type of volcanologist being arse bothered with the water part was geothermal volcanologists, and we are far and few in between.

So, to understand things we need to study water for a while.


Don’t tickle when wet

Water is an amazing and life-giving fluid existing in a surprising number of different forms. Let us get more intimate with those forms.

First of these forms we have the whisky cube form known as ice. The only version I like is the ice cubes in a drink, I come from Northern Sweden, and we hate Ice in all other forms. It has a magical property, and that is that it takes up a larger volume in frozen form and is thus lighter than water. This is why it is floating on top of lakes.

This is important to people from Northern Sweden since it makes it possible to drill holes in the ice to fish. It is a very miserable and cold version of fishing. It also gives us the opportunity to drive around on top of lakes with building material where there are no normal roads.

Then we have normal water existing between 0 and 100 degrees if we are at oceanic altitudes. We drink it, swim in it, drown in it, use it to cook, and so on. Most people use it to make coffee or tea. It is more often beneficial than not.

Above 100 degrees Celsius (there is probably some weird Imperial number for this that I do not know, and am to lazy to google) we enter the realm of steam. Victorians with impressively high hats understood steam, most of the rest of humanity do not. So, let us don a very high hat and barge onwards into our steamy business.

Isambard Kingdom Brunel with impressive hat, he understood steam well. Wikimedia Commons.

As your teakettle starts to boil you will see white stuff start to waft around, most people think this white stuff is steam. Alas, it is not. It is tiny water droplets that are suspended in the air. They form as the surface turns 100C and steam forms to instantly cool below 100C and the droplets form. The steam-layer is literally one molecule thick top-layer of water, so you will not be able to see it.

It is though amply possible to hurt yourself with your white fluffy wispy stuff. But, to get steam we need to raise the temperature beyond 100 degrees Celsius.

To go beyond we need to ad another force, more heat does not cut it, that would just produce more low energy suspended water droplets at a faster pace. We need to insert pressure into our equation.

Water is funny, it will boil at different temperatures depending on your elevation, this is due to the pressure dropping the higher we go giving us lower and lower temperatures for when the water droplets will form what we call “steam”.

If we instead increase the pressure, we well and truly reach into the realm of flash steam. This is any temperature between above 100 and 184 degrees. In the latter case we need a pressure of 10 Bar (atmospheric pressures, the atmospheric pressure is really 1.01325 Bar, but close enough). This is the same pressure you would find at 100 metres depth of water.

Now imagine being that 184 degrees Celsius pressurised water, as long as you are at or above this pressure you are water, but if you even drop a tiny amount below this pressure, you will instantly flash from 1 litre of water into 2100 litres of suspended water droplets. But if you are contained in a volume less than 2100 litres you will stay in true steam form above 100C.

If you are above that temperature you will get something called dry steam, it is an invisible mess of hotness. It is steam kept at high temperature and pressure, but below the flashover point.

Now, remember the poignant word for us is flashover, this is the point where any amount of water will explosively decompress from water into steam.

There is though one step up from this on the giggly tree of water. It is called Supercritical Fluid. It is water that is at such a high temperature and pressure that it simultaneously behaves as a fluid and a gas, while being neither of those things.

If pressure has the upper hand, it is behaving more like a fluid, and if temperature has the upper hand, it behaves more like a gas.

Steam and water up to this point has been manageable, you obviously need to treat it carefully, but you can safely build systems to power ships, steam locomotives, and all power generation plants with it.

Well, the safely part is not true. Those high hated Victorians literally blew up tens of thousands of workers during the industrial revolution before they mastered their craft, ho-hum history is fun.

Water in supercritical form is the suicidal psychotic giggling version of water, it not only wishes to not exist, but it at the same time also wants to take everyone with it in a big boom. If that was not enough, it likes to go through solids like they where made out of paper. It is also very good at dissolving solids. You need specialised materials to even contain it.

So, you want numbers on this branch of the giggly tree? Supercritical water forms at minimum of 373 degrees Celsius and 220 Bars of pressure. Yes, this is the minimum, in some volcanic systems the Supercritical water can be up towards 800 degrees with corresponding mind-numbing pressure values.

This is the only form of water that could have caused the explosion at Hunga Tonga. There may have been other more normal forms of water involved, but they lack the energy density to produce that kind of explosion.

Incidentally, 220 Bars of pressure is reached at less than 1 kilometre’s depth if we use the specific density of bog standard rock (2.3kg per litre of volume, it is probably something in Imperial that is really hard to calculate).


What was down there?

Hunga Tonga becoming Hunga Byebye. Image from Himawari-8.

If you are like me, you will often and fondly imagine that you are a piece of drill steel being drilled into a volcano. It is not as bizarre as it may sound, after all my daytime job is to plan how to best drill into volcanoes for geothermal fluids to drive geothermal power plants with.

Even though we do not exactly know how Hunga Tonga’s geothermal system looked like, we know a lot about geothermal volcanic systems in general. After all, people have been drilling into them for quite some time.

Most often the drilling has been down into more normal forms of geothermal water. But, at times we have found Supercritical water down there.

A caldera is most often a closed off geothermal ecosystem. At the border of an active caldera, you often have an active ringfault, the inner side of it is often filled with material that is easily permeable to water, while the outside tends to be more sturdy.

Int the case of Hunga Tonga this geothermal ecosystem had a free and endless supply of surface water in the form of the Pacific Ocean. And over time that water slowly permeated down through the crushed up rock that constitutes the roof of the magma chamber.

As it went down it heated up and started to pool in layers (geothermal aquifers) depending on pressure and temperature. The upper ones would be the flash steam portion, but that is not as such interesting to us.

We are mainly interested in the water that climbed up the giggly tree hellbent on throwing itself down, aiming to hit every single branch, in other words let us stick to the Supercritical water.

There was probably one such supercritical layer slightly below 1000 meters depth. This would have been the prime driver of this layered volcanic cake (Sluika = Layered cake in Russian, just another hilarious detail).

Below that there was at least another layer of even hotter and more pressurised supercritical water. There is circumstantial evidence of a third such layer, so let us say that there was 2 to 3 supercritical geothermal layers inside the caldera.

These layers often move about upwards and downwards as they go, and the water is circulating around in them in unexpected and intricate ways.

At older more mature calderas like Yellowstone the supercritical water will find ways upwards with time, and they form some of the more spectacular features like geysers, hot pools, and all the other assorted geothermal joys in life.

Hunga Tonga was young and probably had not had time to become a truly circulating geothermal system. Well, not as far as we know that is.

As long as there was no eruption the supercritical water was happy where it was, it was of course trying to run away to the surface, but it seems like it was very slow going. And that was a good thing since there seems to have been 0.5 cubic kilometres of giggling hell-water down there.


The recipe for doom

The reason that these explosions are rare is because you need a large eruption to kickstart them. A normal eruption will just punch a hole straight through the aquifer with the lava quenching the hole as it passes through. It is like the lava is wielding the aquifers shut as it passes through them.

Most of the water that was seen in the vent came from much more shallow infiltrations of sea water, so let us not mix them together. What little came up from the depth just worked as an additional driver of the eruption.

All was well up until the 14th of January. It was a typical fairly benign Surtseyan eruption slowly building up to an archetypical VEI-4 eruption. On the 14th we had the main eruption, a VEI-4 of some magnitude that removed quite a bit of the island the vent was located at.

It was this excavation of material that spelled the doom of the caldera. Instead of rockmaterial of various sorts compressing the first supercritical layer we now had comparatively lighter water on top. Instead of the 220 Bar we might have had as little as 100 Bar.

I wish we would have had instruments and a camera there when what followed happened. It would have shown a wild ride.

As the pressure from above was lowered the Supercritical water started to move from a more fluidlike state into a more gaslike state, in turn pushing what was above upwards. In the first hour the uplift was probably just a few centimetres, but in the end the ground probably bulged several metres an hour.

In the end the rock layer could not hold it back, instantly all of the supercritical water transformed into dry steam (flashover) and as it did so, it flung up the rock above it in a process taking a second at most. With this layer removed there was not enough pressure left to contain the next layer, and that went up a few second later, and most likely the process had a final third explosive decompression.

All that now remained was for the ocean to fall into the hole that had been produced. At this point there was just a little bit of boiling of the sea water, and the eruption was halted for this eruption.

In a while an “Anak Hunga Tonga” will be born as the volcano rekindles its work, but that is a story for the future.



The question that remains is as follows: Have we just been lucky? Is this a style of eruption that could be far more common that we previously believed?

I think we have been lucky indeed. It is most likely far more common than previously believed, because this type of eruption has a much more common form named a Maar-formation.

Unlike a normal Maar-formation (that can be quite ugly) any calderas contain large amounts of supercritical water, and in my view, it is imperative that we upgrade our risk-assessments to also include this style of eruption.

For calderas near cities like Campi Flegrei it is important that we drill deep into the roof of the magma reservoir to build accurate maps of how much supercritical water there is, and where it is located.

This was a fortuitous wakeup call for science. We need to learn, and learn quickly, because having Tsar Bomba going off next to Naples is bad mojo indeed.


847 thoughts on “Hunga Tonga and The Supercriticality Event

  1. A pretty shallow earthquake near Tonga:
    M 6.2 – 225 km WNW of Pangai, Tonga
    Time 2022-01-27 07:40:05 (UTC+01:00)
    Location 19.068°S 176.349°W
    Depth 4.2 km

    • I would like to remind everyone that an M6 anywhere even remotely near Tonga is locally known as an ordinary Thursday, and has nothing as such to do with the volcano.

      Tonga is one of the most seismically active spots on the planet, and anything below M6.5 is counted as small.

      Just wanted to give a bit of perspective here.

      • Based on the very uniform magnitudes of shocks around Hunga Tonga that now extend to 30 miles (50km) away, my thinking is this area must be in a stress shadow following some recent nearby tectonic activity…i.e. the cluster resembles an aftershock sequence?
        I wonder if the shockwave jiggled the upper crust enough to cause it to flex and crack, with the M4-5’s releasing the built up stress since the last major (>M7.5) quake.

  2. To Zach
    when it’s morning in Scotty-Land:

    You got back to the question writing: “Well, looks like this theory is disproved, but how could anyone explain about odd coincidences where the Earth has a moon and that other rocky planets that do not have large moons don’t have plate tectonics or at least limited tectonics.”

    1. Probably different core
    2. Probably different mantle convection
    3. Different tilt.
    4. Different motion, very nice day and night-rythm
    5. Water
    6. Certainly different gravity
    7. Right distance from sun (still).
    8. Right weight.

    To be prolonged by whoever feels like it.
    So, the moon is only one thing. You have many explanations. A whole bunch of them. But of all things you ran into a moon model that has to be tested.

    Then the asteroid belt (sorry, Scotty), then water.

  3. Very nice close up look at a hornito on Kilauea right now.

    Hornito is basically a spatter cone but where it forms over a lava flow instead of a vent, a rootless cone. Usually they form over well established tubes, but they can also form on thick lava lake crust, there are photos of hornitos on Erta Ale, and also some near Mauna Ulu and Pu’u O’o, and I think also on Etna.
    I think this is the first time I have seen one so far away from the vent area in this eruption though, it shows there probably is an actual vent submerged in the lake itself in addition to the visible one, allowing for gas rich magma to enter the lake directly and vent at the side in a fountain like we see. Or the conduit below the visible cone is actually a lot wider than we thought, and connects directly to the lake under the crust, which is what I expected but had no proof of until now 🙂

    I guess now the real question is at what point would we just call this an actual vent, how thick does the lake crust need to be?

    • Actually, it is right over the old downdropped block that used to have a lot of fumaroles on it, I wonder if maybe those are still venting and finally built up enough pressure? it is a small feature but fountaining quite strongly, and more like a strombolian gas jet sort of fountain than a spattering vent.

      • I think you might be right; could be gas from the fumaroles.

        Wish we had better coverage, such as we did in La Palma and Fagra-unspellable. I know USGS has said they don’t have the bandwidth, but, there are cell towers in the area (at least four within a mile). Surely the local news station, or a website, might be interested in setting up a webcam.

        • I think it is something to do with the location being in a national park, it is their decision to make not that of USGS.

          Still, they got permission in 2018, why not now 🙁

          • Did we actually get Kilauea streaming live footage in 2018? I remember live feeds from Puna (all private, like the rooster cam), but not Kilauea (though this may be just me not finding said feeds at the time).

            When asked about the lack of live video, USGS said this in September 2021;
            “Unfortunately, with the loss of our the former HVO building at the summit, we don’t have the infrastructure or bandwidth for streaming video from Kīlauea, We’ll also need permits from the Park for special equipment, since this is a culturally sensitive area.”

            I don’t think it’s an issue with the National Park Service, which has loads of live video webcams in national parks, well-publicized on their own website. Here’s an example.

            More to the point, the camera infrastructure is already there (It’s how USGS gets the video it does post), so that’s not the issue. As for the bandwidth issue; USGS says live feeds exist internally for monitoring. Where do they do this from now (since losing their office at Jagger museum in 2018)? The USGS HVO is currently working out of HVO offices in Hilo, on Kamehameha avenue. Do they have a broadband connection there? Yep. Do they have high-bandwidth capability between the cameras and the Hilo offices? They must, if they are monitoring them from there live, as they say they are. It’s also worth mentioning that there are at least four 4-G cell towers within two miles of the summit, and in direct line-of-sight. There’s also broadband (and WiFi) at Volcano House, right on the rim.

            I’m not suggesting any sort of conspiracy here (I’ve always believed that one should never attribute to malice in a government agency what can be explained by incompetence) but something here does not seem to add up.
            What I find most objectionable is if they are not sharing their live feeds with offsite vulcanologists; it’s not mere entertainment. There’s a great deal to be learned (as we’ve seen from other live feeds) regarding the science and dynamics of eruptions. It also seems to me that the most efficient way to do this is to set up a youtube or similar live stream, which most any teenager seems able to do, and thus might be within the ability of a massive government agency with an IT department.

          • I think it is more if they make their feeds public it could interfere with their own feed to HVO, their website is known for dying when something interesting happens so I think maybe their tech team is not the best… I also would think it is because there is not anything particularly significant going on too, in iceland it was an eruption near Reykjavik, and at La Palma it was very destructive and also visually impressive, and in both cases also there were no issues of obtaining permissions to film. Kilauea in 2018 would fall under that same category, but now it is not so much. In saying that though, the lake is getting high enough that the top of the vent is visible from the north side of the caldera now, which is where Volcano House is, so maybe in the near future it will make more sense. By the start of 2023 it will probably be overflowing onto the downdropped block, which is easily visible anywhere around the caldera.

            There was lifestreams of the caldera collapsing in real time in 2018, though only for the last month of the eruption I believe.

          • Hrmmm. It wouldn’t harm their feed from Kilauea to the HVO offices at all, if they sent the feed out from their offices rather than Kilauea. And they do have broadband at their Hilo offices.

            Perhaps their IT department needs to ask a random 13 year old youtuber for technical advice on how to do this? 🙂

          • Should say I meant their website crashes from heavy traffic when something interesting happens, it did that before 2018 but even the new website struggled in 2020. So I think they fear the same if they try to livestream.

            But then there are months long live streams on youtube . I think there is probably some governmental reason they cant do it. That is probably out of anyones control who is on site, im sure most of the staff would like public live data available. Given they had to take a month to get approval to fly their drone into the caldera though…

          • I don’t know if there’s any governmental reason why a US government agency couldn’t livestream on youtube. It’s not as if agencies don’t already have Youtube channels. But, maybe USGS doesn’t know that it has a youtube channel already. 🙂

            I do know of one US government agency that livestreams on youtube; NASA.

            And it took USGS a month to get permission to fly a drone? Yipes! I took a look, and it seems that you can only fly a drone in Volcanoes National Park with the written approval of the superintendent, and there’s no exemption listed for government agencies or emergency services. I wonder what they;d do if an emergency rescue team needed to use a drone; make them wait a month?

          • USGS does not own the place. It a research organization. The volcano is governed (and owned?) by the national park service. Complaints should be addressed to the management, not the users.

          • Albert, you’re quite right; complaints should go to the management, not the users, assuming the management is the cause of the issue.

            However, my point was that when it comes to the USGS HVO offices in Hilo, USGS is the management. That’s not National Park land at all (though most of Kilauea definitely is). My point was that USGS already has the needed equipment inside the park, no need to install anything there, so what, exactly, would USGS need a permit from NPS to do regarding sharing a video feed that already goes to their Hilo offices?

            As for the National Park service, their rule that apparently made the USGS wait a month to fly a research drone inside Halemamuamu is IMHO preposterous. If the drone had crashed, there’s no real risk of harm (especially if it hit the churning lava lake) and it’s for a legitimate government function. (USGS is also a public safety agency). I looked up the rules for Volcanoes National Park; they require written permission from the superintendent for any drone flight – no exceptions for other government agencies. This is very unlike another national park I checked; Yellowstone. There, there is a very real risk of damage if a drone crashes into a thermal pool or geyser vent; it can do real and lasting damage. Yet, there, there’s an explicit exemption for other government agencies and emergency services, and even a permit process for commercial use. Volcanoes National Park, where there isn’t the same kind or risk, is vastly stricter, and apparently strictest of all in the safest area of the entire park (due to a crashed drone there being a self-solving problem) Halemamaumau (at the time, it was nearly vertical-sided with a churning lava lake at the bottom).

            So, you’re right. On drone flight by other government agencies, the National Park Service, and particularly Volcanoes National Park, seem to be the ones to complain about. I take a very dim view when mindless bureaucracy prevents needed and urgent research (such as that drone flight, given the concerns at the time that Kilauea could be heading for an explosive phase).

  4. Just a little note, the sunrises here in Rio the last two days have been an absolutely glorious bright orange. Pretty much right on schedule.

    • Envious. Last night we had clear skies but no more colour than usual

    • Red sky at night, shepherd’s delight.
      Red sky in morning, shepherd’s warning.
      Means you’re getting rain tomorrow…

      • That’s normally based on a prevailing westerly wind – and dust in the air having been lofted by warm weather – so if the sun shines through the dust from the east (sun rises in the east) then the warm weather is east of you – and with the wind coming from the west that means it is blowing away from you. But if the so if the sun shines through the dust from the west (sun sets in the west) then the warm weather is west of you – and with the wind coming from the west that means it is blowing toward from you.

        but it should say something simpler like ‘Red sky where the wind is blowing from – weather should be good soon. Red sky where the wind is blowing to – some warm weather has probably passed on by’

      • It is when the air takes on a golden or burnished gold colour you will live in interesting times.
        Before really big storms, or hurricanes the light will often take on a golden colour.
        When I had the great unfortune of sailing through a heavy cat 4 hurricane (Floyd) I watched how the air itself somehow went from light gold over to a heavy brownish gold hue right before I entered into the rain wall.
        Only tip for survival I can give is that the sooner you become insane, the better.

        • I was (almost) in Floyd. I was at a meeting in Orlando and scheduled to fly home that day when the airport closed. Since Floyd was a monster, there were (minor) hurricane force winds forecast as far inland as Orlando. It turned out that it was only tropical storm force winds in Orlando, but I do remember how the pine trees around the hotel were violently whipped by those winds.

          I’m not sure I can imagine what it would be like bearing the full brunt of the storm on a boat on the water. Insane, indeed. Where were you and what were you sailing?

          • I can. I was on a boat for eight as a student – we were allowed then to learn sailing for free – and I had to do some trips for the exam then called coastal shipping licence. We were not at all in a hurricane, but in a storm with winds up to 8, up to ten in gusts. We had learned what to do with the boat in those cases, but it was still extremely frightening. One of the worries was the DDR, as in storms you never know whether you have figured out the right course, but we had. The good thing is that you do not always think about yourself. You want to save the boat. This was our night trip. We all passed. I couldn’t drink rhum for a while as we emptied all the rhum and I had to throw up. When we arrived in the morning we said unisono that it had been the best adventure ever. We would have gone right back. But – as I said – it wasn’t a cyclone. Different I guess.

          • It’s not the worst thing though. The worst thing is fog. And this also goes for car driving. Fog took the Andrea Doria down. They both went to the same side, unfortunately, and then they collided. That is another interesting story to never be bored.

          • I had just bought a 52-fot Sparkman & Stephen ketch on auction from the ATF (smuggler-boat got a new meaning).
            I was intending to sail it a bit North to have it fixed for my upcoming Atlantic sail to get back home to Europe. And as I was bobbing along Floyd changed track. Bad bad Floyd, he was much better as a drunk English chef, then as a hurricane.

            It was also when I learned that you can use a 52-fot ketch as a surfboard. Becoming insane helped me invent that technique.

    • Sunrises? It has been days since we could see one. Been fogged in for days!

      On another note, I think this is for Chad. Swans are not limited to the Atlantic. We have plenty of swans on the west coast of the Pacific Northwest. These are white and they are not Mute swans. The swans spend most of their time in Canada and Alaska but many winter south of Canada. The majority of swans we see are Trumpeter swans–Cygnus buccinator– but we do get the occasional Tundra swan–Cygnus columbianus. (In the UK you would know these as Bewick’s swans.)

      • Somebody should probably fix the sun.
        All I have gotten since mid-october is wind, rain and soul-sucker-greyness…

      • Carl You should move to Reunion with wife later .. time for a change in climate

        Its true that north west europe haves very mild winters, rarely snows in Denmark or South Sweden
        But its gloomy and cloudy and lack of reflective snow on the ground makes our winters very dark indeed, also the high coastal humidity makes it feel like being in icey water outside

        I rather prefer a – 7 C very dry winter .. but thats further up

        But Northen Canada and Siberia at same latitudes gets down to – 50 C and below, they are continetal interior winters .. very diffrent from Carls coastal oceanic winters

        But I rather prefers the tropics too just as Carl do

  5. The centre of the galaxy is an interesting place. This is the latest image from the South African MeerKAT telescope

    • Brilliant, but the web page manages to avoid mentioning the working frequency range, I presume its short wavelength radio waves, what things are bright at these frequencies isn’t really mentioned.
      Lots of pretty pix though.

      • It is the radio L-band, at 1.3GHz. It is mainly synchroton emission, so high energy electrons: supernova remnants, pulsar wind nebulae, shocks. The linear features are magnetic shocks

        • While mostly everyone I think will agree that shocks are major drivers for particle acceleration and thus the existence of ultrarelativistic leptons, I would fairly say we have no real clue what exactly the filaments are, and most importantly why they are so sharp…

          • I was at the VLA telescope when they were first discovered. We had great fun trying to argue what they were. I argued against cosmic strings. I expect in some cases they start at one location and get pulled into a string by the electrons following the magnetic field line. In other cases the magnetic field follows the edge of a wind bubble. Guess work! It is still exciting.

          • I will side with Albert on this one, cosmic strings are a bit out there.
            And electrons at high speed along a magnetic field line is at least congruent with QED.

            (Might just be me, I always stop understanding things after the word “string” appears… strings are best left to cats)

          • I also do not believe they are cosmic strings (rsp. a connection to them). But the spectrum of the electrons inside them does not seem to match that of the shell SNRs (an obvious source of magnetised shock fronts in the Galaxy, arguably the dominating one TODAY). What is striking in the new image is that the most intense cluster of filaments traces one of the rims of the radio bubbles. And actually there is one the other side the same effect. Maybe that is an explanation, shifting the mystery to the origin of the radio bubbles (AGN, starburst…?!), and to how the filaments stay so sharp so long.

          • I have not seen them elsewhere than in the galactic centre. Perhaps I missed one .. but if true, there is a local effect. The black hole is an obvious suspect. But the interstellar magnetic field may also be strong here. Some te years ago we found indications that fields here had been strong enough to affect star formation

            I love this part of the image. A large supernova remnant, a pulsar which has shot out from the remnant (a remnant of the star that exploded) and developed a tail, and a bendy filament called the snake apparently chasing the pulsar.

          • That is one hot picture (pardon the pun).

            I had not seen this image, thank you Albert!

        • You missed it, both. It is the different strains of Coronavirus, they didn’t escape from our volcanoes after all, three crosses.
          😉 🙂

        • What I understand is that you, the physicists learn from it like we learned from the Electron Microscope and other things.

          What I don’t understand, also not in the media, what is that knowledge good for? Could you explain it some day in a piece? It would interest me what the win is, the purpose. Is it a win-win situation or just a gain of knowledge?

          • That is what we never know.
            And, I would state that knowledge for the sake of knowing is quite a beautiful thing in and of itself.

            And, in the end we will need to solve the heat death issue somehow, and learning about these things will probably be important.

          • Why do astronomy? Or rather, why pay for it? Three reasons. First, curiosity. People are interested in the Universe we live, as shown that pictures like these go around the world in blogs and newspapers. They want to know more, and the knowledge becomes part of our culture. It changes how we see ourselves. Second, we benefit from the side effects. Astronomy, as many other sciences, try to do the impossible. We push our instruments to the limit, and need to go beyond. That requires new technology, and you never know where that ends up. The CCDs in your cameras were developed from astronomy (and was awarded the nobel prize). The technique behind wifi was developed for radio astronomy. CERN developed the touch screen – and the internet. (Imagine if the internet had been invented – and patented – by facebook!) And now we develop Big Data: the next major telescope (the SKA) will have a data rate close to the total internet traffic in the world. We are creating techniques to deal with data that comes so fast that it is impossible to write it to disk. Third, we develop human capital. People study physics and mathematics because of their interest in astronomy (and other topics, of course), and learn skills that the world needs. Some go into research, but many go into other jobs in the general economy. Some even teach your children.

            Is that enough for you? Astronomy is expensive. But it is also a bargain.

          • Well said, Albert! Also, while it is true that astronomy is very expensive, the money spent is never lost to the economy. It goes e.g. into salaries, and people receiving those salaries of course spent it on things. Or it goes to companies who build e.g. telescope structures. And there it feeds engineers, mechanics, all other staff…

          • I would also like to add something different to the discussion.
            It is also art. People around the world, me including, find it beautiful to behold the images that come.
            That beaty is food for our curiosity as we behold what is around us.

            And without that art since the dawn of time we would not have mastered fire, invented the wheel, nor developed a language to convay these thoughts. Without this art we would be grunting beings, or even just a smear on the path of some other species finding interest in the art that is science.
            Without it we are nothing, just dead automatons scratching our groins while grunting.

            Instead those first hominoids lifted their eyes towards the stars, and started their journey to become humans as they beheld the beauty of the Universe.

          • Is it enough? It’s a start and thank you both for taking the time.
            Why do astronomy? The Isaac details explain it, it is all of an incredible beauty. Breathtaking. When it goes more into detail like with Meerkat it get’s closer to in my profession where things become too precise for the normal human being to please the eye. That’s why I was asking.

            I believe that the whole thing is extraordinarily pretty and miraculous, beginning with Earth, the Solar System, the gasses of Iupiter and Saturn, their moons and the galaxy. When we go to close we might learn something, you first, but I feel that the beauty of it might be lost.

            I see a dying star – I thought of our sun in the far future and became slightly sad. But maybe this is just too simple.
            On the other hand I read that new stars were seen around there which surprized everybody.

          • I understand the motive perfectly well.
            When I first got to know the stars really well without using a telescope I was too old to study that and had already finished my studies and a child and a job.

            We were staying on the beach of Teneguia, La Palma, and I couldn’t sleep, some endemic birds were talking, yes talking like humans, in the rocks above us (maybe the Canary Raven or some endemic duck), and the rocks were hard, and I couldn’t sleep, and I saw the stars of the Zodiac walk by, Scorpius very easy to see, watched all night, got a book afterwards.

            I remember it clearly today. In cities this is impossible. Down there it was completely dark. I was fascinated. So, perfectly understandable from that starting point when people go out and study it. If I had been 18 I might have done it myself.

          • I have to add that you always see three Zodiac constellations at a time. Of course you rotate with Earth, but thankfully we do not realize it and think they walk by on the night sky. I saw them from Scorpius to Gemini, and had some bacic knowledge and could clearly define Scorpius, Sagitarrius, Pisces, Taurus and Gemini.
            I should have talked more about this to other parents as I consider it one of the more important nights in my life, a night that makes you more aware, more curious and more alert.
            I once read in the German magazine Spiegel how a teacher had a hard time persuading parents to do a trip to the mountains. The kids wanted – as usual – a city trip (and then go mainly shopping). After the trip to the mountains they told similar stories to my story here. It moved them and changed some of them. So to get them more into Physics, Geophysics, Mathematics, Geography and Geology I consider it necessary to break their wall of consumerism and show them nature at an early age. The British are not so bad in this with their Prince of Edinburgh Award, the Germans are awful. Liberalism for Germans is to listen to everybody’s wishes including kids all the time. I think that teacher was great.

          • The great Carl Sagan once said something to the effect of, “we are a way for the universe to know itself.”

            Speaking as one tiny speck of the universe, I’d like to know all I can. And I think there are many out there that feel similarly.

        • Just to be fair, today a warm, sunny and windy weekend day.
          UK electrical equation
          12.6% fossil
          52.2 renewable (8% solar, 43% wind).
          21.1% other non-fossil
          14.1 imported

          • You probably should add to this that it is on a winter weekend day, when usage is quite a bit below the peak. Last night, wind covered over half the electricity needs of the UK, and fossil fuel less than 20%, but night usage is of course lower. This is about as good as it gets in winter. Or in summer: electricity usage is lower in summer but so is wind. The effect is that fossil fuels provide on average about the same absolute amount in summer and winter. We often talk about fossil fuel needing to cover the variation in renewable supply. That is true short-term, but long-term it is the other way around. Of course that is the UK: it will be different in other countries.

    • Is the bright spot at the centre where the black hole lurks?

      • The exact center is at the upper rim of the compact bright “bubble”. The black hole itself (rsp. the shadow it casts) is at that resolution not visible. The bright stuff is a major obstacle in achieving this for the Milky Way, using EHT…

      • More like Croquettes in Brodo with some cheese in it.

        I hugely prefer impressionist paintings of Isaac:

    • Incredible image. Thanks for posting it.

      Is there an explanation for the blastula-like object in the lower right?

      • It is the same object shown in the other picture. It is a bubble blown by a supernova

    • That is quite an image! The lair of Sagittarius A* is indeed a fascinating region. The clarity and apparent sharp density changes are astounding – a puzzle indeed.

      Thank you!

  6. Not sure if that image belongs in the Museum of Natural History or Tate Modern. Probably both.

    • Tate Modern. My example of Isaac belongs in the old Tate Gallery or the National Gallery.

  7. And on Mars NASA continues to struggle with bits of Mars where they shouldn’t be. Fortunately they have no end of high tech sophisticated methods for clearance. Last week they were hammer drilling thin air and this week…

    NASA’s Perseverance Mars Rover
    When you run into a challenge, sometimes it’s best to step back and shake it off.

    I reversed up onto some nearby rocks to get tilted, and did a twist with one foot. Somewhere along the way I’ve shaken loose the other two pebbles in my sampling system. Back to #SamplingMars soon!

    But no Mars isn’t just content with attacking Perseverance with pebbles it is also trying to bury the poor rover in
    sand. Mars Guy, Professor Steve Ruff has the details in the latest video.

    Episode 42
    Dust storm season has come early to Jezero crater. Winds have dumped an unprecedented amount of sand on the Perseverance rover, disturbed its surroundings, and grounded the Ingenuity

    • Squonk, you follow this closely, so perhaps you know the answer; Why does Perseverance take samples, encapsulate them, then leave the samples behind for future recovery? (basically, leaving samples behind along its entire route) Wouldn’t it be easier for the future mission if, instead, it emplaced the encapsulated samples in an on-board holder? Just an exposed rack or basket would do – and the total mass seems negligible for rover operations. But, instead, the future mission will require an autonomous rover to seek out the samples left behind, over many miles of terrain.

      Any idea why they did it this way?

      • I think one reason is that If Perseverance got stuck somewhere with all the samples onboard it might be potentially very difficult (or even impossible depending on how it was stuck) for a future time constrained mission to retrieve them given current design. If you assume Perseverance is still operational when the return lander arrives then things are much simpler – but they can’t assume that.

        • Hrmmm, I think you may have a very good point on that. Spirit got stuck in sand, which might make a sample return retrieval problematic, were Perseverance to do the same.

  8. I bet the Aleutian Arc had similar eruptions in prehestoric times or even historic times. Looking at the map in here

    is enlightening. There’s a nice island arc ending inland in Alaska.
    Down there is a nice island arc ending in New Zealand.
    What is the American plate up there is the Indo-Australian plate down south.

    Part of what is seen of the Aleutian islands must have been under water in prehistorical times and come up, partly because of the pressure of the Pacific Plate, partly because of lowering sea levels after the Cretacious.

    I think that the setting is similar. Augustine is a lot higher but has done alternating construction and collapses all the time.

    So we might have seen the diificult birth – failed for the time being – of a subaerial volceno in an oceanic setting. An idea, born itsself from comparison. Beauty of the north:

    • That volcano looks quite beautiful 😀
      Thank you for posting!

    • There also are still quite a few Aleutian volcanoes that are subsea or barely sitting above water-level. Quite a few island-destruction events (or partial island destruction) have occurred which would imply likely seawater breaches of a magmatic system.


    50:28 – 54:03 nice day / night footage of Nyiragongos 1980 s crater activity taken by Hauron Tazieff .. in daylight it looks quite cool / cold in temperature, much colder than Hawaii and seems logical, Nyiragongo is the result of very small ammounts of partial melting, so it should be quite low in temperatures. Sillicate Lavas that are as alkaline as Nyiragongo are strange stuff for soure

    But the extremely low sillica content gives it a viscosity similar to Hawaii at lower temperatures than Hawaii

    • It is always fascinating to me how despite the fluidity the lava is still fountaining pretty violently, it is almost strombolian even right out of the lake. The dense steam is probably an atmospheric effect but there must be a lot of gas in the lava here, probably a lot more CO2 than in tholeiitic basalt.

      This thing must have been one hell of a lava geyser in its cone building days, something like Pu’u O’o but the size of a mountain, probably so steep even these fluid lava flows would disintegrate into glowing avalanches on the flanks during the bigger eruptions.

      Maybe a close cousin to Nyiragongo is Villarrica, which is still in that early stage. Eruptions there consist of semi-continuous open vents with small lakes, and about once a decade the whole thing goes full lava geyser, 1971 saw the mountain split on its axis and erupt around 30 million m3 of lava in under a day, almost a VEI 4 hawaiian eruption. There also was an actual VEI 5 eruption there 3700 years ago, erupted so fast that the lava was more like an ignimbrite than a normal lava flow. Must have looked like someone opened a portal to hell on the mountain…

    • Yes Nyiragongo is a young ultrabasic lava fountain cone .. basicaly an overgrown Puu Oo .. but lava fountains in Nyiragongos youth where probaly kilometers tall and more like a glowing subplinian gas tephra geyser

      Woud be a spectacular sight in Nyiragongos high fountaining years a few 1000 years ago.

      In the night Nyiragongo woud be glowing orange with loose tephra with yellow hot millions of pieces tumbling down .. huge ligthing bolts flash through the glowing curtains .. the glowing pillar woud have a gigantic pyrocumulus above it

      In daylight it woud be a dark tephra shroud over Nyiragongo with massive cumulus convection and lapilli failing everywhere, thats how Nyiragongo got its steep shape

      Its became a lava lake vent volcano because of changes of the system How its allowed to degas. Nyiragongos Nephelinite lavas are one of the most CO2 rich on the planet .. Very very gas rich magmas

      In its early years it probaly was a direct pipe down to the astenosphere melting zones. Now its having shallow stoorage system.

      A few 100 years ago a very shallow magma chamber must have drained to form todays Caldera, and the cones top collapsed and caved in, the caldera edges have many lava channels thats been cut by the collapse, Nyiragongo was many 100 s of meters higher before its caldera formation

      • Why caldera, Jesper? I don’t understand it. For me it is a stratovolcano with a central crater and a crater lake inside. If it collapsed it would form a caldera. So why caldera?

    • Nyiragongo probaly looked like Villaricca and Shishaldin during its high fountaining years .. and woud be apocalyptic lava fountains.. more like Plinian tephra columns

      The whole Nyiragongo is ultrabasic in compositon, so something else rather than composition gave it its steep shape, and very very high lava fountains coud explain that, its changes how the system handles its degassing

    • The current summit caldera, woud be an Impressive event that formed that
      Probaly Nyiragongos biggest lava flow or paroxysmal event since it was born. Perhaps a bit bigger than the Leilani eruption even

      Probaly was a very shallow magma chamber that drained itself into Nyiragongos rift system and collapsing the summit, an enormous event for a small and young volcano.
      And probaly happened very recently too, perhaps a few 100 years ago

      It coud also be a product from a violent plinian fountaining lava eruption at the summit like Etnas Big eruption in roman times that collapsed Nyiragongos summit, we will never know since the deposits are long since buried

    • A summit crater thats large enough is called a caldera

      Kilaūea haves calderas, Nyiragongos sister volcano haves a caldera, Galapagos shield volcanoes haves calderas

      A large crater on top of a volcano is called a caldera

      And There are pure caldera volcanoes that are only a caldera and No Peak at all like Taupo and Yellowstone

      There are effusive drainage calderas and explosive calderas too, most effusive calderas is formed by magma drainage that basicaly removes an upper shallow magma body

      Nyiragongo is an ultrabasic pyroclastic tephra fountain stratovolcano that haves a caldera on its top, the whole upper cone caved in not long ago

  10. During the weekend I will stop Pangea from reforming, crack a continent and talk about a VEI-8 Krakatau…

    Small scale geography is just a tad boring after all!

    Just giving a bit of a teaser here. 😉

    • I don’t think it will be Pangaea, but Gondwana of the north. Antarctica will stay south and also East-Africa and possibly also South-America, but that is a difficult guess as it has a spreading-ridge on either side.
      I can clearly see it as the first Gondwana with a huge continental mass in the South and a tiny Laurasia, next time around the North Pole, end of long trip with nearly desastrous collision 250 Ma.
      If you crack something it would rather be in Africa (east or middle between Cameroon and the rift) or in Russia (Lake Baikal). Looking forward.
      You wouldn’t break South-America away, too scary for your wife and others.
      Sounds good. Like playing cards with crust pieces.

      • It would take a long time to crack open central Africa even once the Somali plate has gone. It would have to get stuck as it drives north and open up a serious amount of strain.

        Baikal is more likely, it can head south and connect with the Amur plate counter-clockwise rotation or if it reaches far enough west perhaps Pakistan and the Makran trench or the Zagros fold.

        I’m curious as to whether or not Lake Balkash in Kazakhstan is the western-most expression of the Baikal rift, it’s not clear how far west it extends

        • I basically think it is stuck, Andy, but things crack elsewhere, all those earthquakes in Italy and Turkey. Look at Albert’s piece about Turkey earthquakes, he has a map in there, all in red.

          • The Anatolian plate is key I agree. Adriatic plate will be subducted and the Aegean sea plate will be squeezed into oblivion. The Arabian plate I think will likely rotate away from Africa and subduct under Pakistan/Iran.

    • Then also the middle of the biggest plate: What if that big mass of Big Island breaks the Pacific plate underneath and creates a spreading centre? Woldn’t be the first time it happens. Geologists are still looking for the precise birth place of the Pacific plate. Up to now: Only ideas.
      As I said: Looking forward.

    • This is only a guess but…
      I think you are trying to prevent the next supercontinent from forming by essentially cracking and tearing apart Africa and maybe having a rift in the Mediterranean Sea, which will lead us to talking about Campi Flegeri.

    • Yes please, we don’t want Pangaea the remake. Remakes are usually shoddily done.
      Let’s have a bit rearranging, Australia in Japan and everyone crushing into each other in the -40C of the North Pole. I’ll stay in the newly tropical Antarctica, far from exploding fire mountains and serious subduction.

    • Carl, I have a request; seeing as how you’re going to stop Pangea from reforming, could you please also stop Hekla from erupting? 🙂

    • Yes, the cone is visible from the north of the caldera now, by the time I go there it should be visible from the Volcano House quite easily 🙂

      Of course all of the lava in that lake, it is at least 90% completely liquid… basically the higher this gets the more catastropic its drainout will be. if the 2018 caldera does fill fully before it drains then we get an eruption of the same sort of intensity and speed as Nyiragongo except with the same volume as Holuhraun, or close enough anyway, 1 km3 of lava in a few days. One can only hope it is not to the east, no one will ever be allowed to go anywhere near a volcano in Hawaii ever again…

  11. A radar image from yesterday. There is still a lot of debris on the sea. Some of it is approaching the main Tonga island.

    • At least one person who stays close to the topic and the area 🙂

  12. Jesper

    I think you should not call Nyaragongo’s crater caldera because it is confusing.
    I have seen enough calderas by now on VC and elsewhere, Taupo, Yellowstone, in the Andes, near Tokyo, Spain (Las Cañadas) and so on. They are mostly oval-shaped and sometimes round and often have new volcanoes emerging somewhere in them.

    Nyaragongo is a perfect stratovolcano with a crater in the centre. The last times it erupted it didn’t collapse but send lava up and out. The only problem with that mountain is that people tend to forget and settle it. It might one day form a caldera though by collapsing.

    If there is a caldera underneath that would be a caldera from an older volcano.
    It is confusing, no matter how runny the lava!!! is. A caldera forming event would also be plinian or phreatomagmatic like we have seen on Jan 14th. or with Aniakchak or Thera 3500 years ago.

    • Etna have done large basaltic plinian eruptions before that have formed calderas

      But most mafic volcanoes haves effusive drainage calderas like Kilauea and Mauna Loa and Galapagos volcanoes

      Nyiragongo is a mafic stratovolcano thats topped by a small caldera, you can have a stratocone and shield with a caldera on top

      Or you can have like Taupo .. only a caldera and No volcanic cone

      • Speaking of which, how is your first post coming along? 😀
        Would like to get educated about Nyiragongo, so keep researching and writing =)
        Better not tell too much into the comments, lest you destroy the surprise 😮

    • Denali, it is not as simple – just check out Vesuvius, or even Etna / Mt St Helens. Jesper is right – a stratovolcano is not necessarily blown away by a caldera forming eruption. Depends on the depth of the magma chamber I reckon, but if it is not far below the edifice, only parts of the mountain can collapse into it or even only the summit area, if not fully emptied out. Potentially the same if only a massive feeder channel or sill collapses/empties out..

      • Okay. Read it all, also the others. Basically meaning kettle and must be made by a volcano, not by erosion. The famous Caldera di Taburiente might not be a caldera, but caused by erosion.

    • It is a caldera because of the way it formed, any collapse structure that is bigger than 1 km wide is a caldera. I think that distinction is made pretty much specifically to not call the chain of craters on Kilauea calderas, but there is no difference in any other way. Explosion craters can be significantly bigger than the lower limit for a caldera, there is no size limited definition, it is about the method of formation.

      Calderas also dont always destroy the volcano, Tambora is still a big mountain, because its edifice was bigger than the magma chamber or was too deep, while that of Thera which was a similar size completely destroyed its volcano, the chamber was shallower or more flat. Cerro Azul/Quizapu had a VEI 6 eruption in 1932 that didnt even make a caldera because the chamber was too deep to collapse at the surface.

    • I think there should be a definition change…
      Calderas would be defined by purely explosive events (I.e. Tambora or Krakatoa or Hunga Tonga). However, “calderas” formed mainly by drainage events should be called “luawai” (after “lua lau wai”, meaning “dranage crater” in Hawaiian, according to giggle translate) or “macro pit craters”, since they kinda form the same way as pit craters and those in between are called “calwei” or “luadera”.
      Think about it, instead of “Kilauea Caldera”, it’s “Kilauea Luiwai” or even the “Nyiragongo Luiwai”.
      Just a few suggestions.

      • I think that would be confusing, and there is no structural difference between a caldera formed in an explosive eruption vertically and one formed through horizontal drainage. Often you get both happening together actually, most mafic calderas have an explosive element (including Kilauea).

        I would not be surprised if we find out there was a flank eruption from Hunga Tonga Hunga Ha’apai before it blew up, that is one way to depressurize the system, and would actually do so at a greater depth which could allow a bigger explosion crater to be excavated, which might be what we observe actually. It is not a shield, but the lava is basaltic andesite so should be quite fluid.
        No proof yet at all but it would not be too unusual, and is almost ertainly what happened at Tofua and Niuafo’ou, its cousins to the north, which are confirmed effusive basaltic volcanoes but which have VEI 6 sized calderas. It is also probably what happened at Kilauea in 1790, and Taal in 1754.

      • I think that there should be considered multiple types of caldera forming events. At least four classifications:

        Simple lateral draining: Kilauea in 2018, Bardarbunga in 2014, Piton de la Fournaise in 2007, or Nyiragongo in 2002 and 2020. Here the magma chamber is drained due to a flank effusive eruption or dike intrusion and collapses.

        Lateral draining with ring dike: Mijakejima in 2000, Fernandina in 1968? Askja in 1875, or Kilauea in 1790 and ~1500. The magma chamber is drained mainly through a lateral dike intrusion or eruption but at the same time produces a ring dike through the ring fault and produces explosions which can alternate between phreatic and magmatic.

        Normal explosive: La Soufriere in 2021, Pinatubo in 1991, Agung in 1963 or Santa Maria in 1902. Plinian eruption with characteristics typical of an eruption of their magma type in which the conduit or magma chamber collapses leaving a crater that rarely surpasses more than 3 km in diameter.

        Explosive with ring dike: Hunga Tonga in 2022, Krakatau in 1883 or Tambora in 1815. Unusually powerful explosive eruption which produces a pyroclastic fountain feeding into ignimbrites. Eruption rates are much higher than normal explosive events of their respective magma types.

        • Seems the important part is that there is a ring dike. Both cases end up with a much more powerful event, regardless of magma type.

          Something I have wondered though, is it possible for a really fluid basaltic volcano to do a variant of a vertical caldera? Normally those are plinian, but the difference between a hawaiian type fountain and a plinian eruption is really speed of ejection relative to the viscosity of the magma, plinian eruptions are fast enough to shatter the magma.
          Thing is, for a volcano like Nyiragongo, a steep mafic stratovolcano, those have got very fluid lava but also great vertical height, it might be possible for that to just collapse, basically erupting all of the magma chamber in an instant, but it is a thin fluid lava not a sticky magma that can explode easily.
          I got this idea after reading about the Pucon ignimbrite, from Villarrica 3700 years ago. Villarrica is basically Nyiragongo 2, it isa tall steep stratovolcano that has got a long standing lava lake, and even erupts pahoehoe which is very rare for an arc volcano. But the Pucon eruption was a VEI 5 and formed a small caldera, seems very excessive for that, and there is nowhere around the volcano to suggest a flank eruption as a trigger. I guess maybe this sort of eruption could be called an ‘ultrahawaiian’ eruption.

          • The eruption rate has a lot to do with the width of a volcanic conduit. The more viscous a magma is, the bigger the conduit is. As long as the conduit is wide enough to allow rapid ascent of magma, so that it doesn’t get stuck like in dome-building eruptions, then the more silicic a magma, the wider the conduit will be, and the higher the eruption rate. So normally the eruption will be more violent with increasing silica.

            However the type of intrusion also matters. In ignimbrite eruptions the type of magma doesn’t seem to matter much as far as I can tell. This might be because ring dikes open in a very different way to other intrusions. Instead of opening forcefully, it does so because the caldera collapses, and the more it collapses the more it opens up. This process might be independent of how viscous the magma is. At least I do not see why there should be a connection. The size of the caldera might be more important, I think. Large calderas like Taupo or Kikai do more intense eruptions than smaller calderas like Krakatoa or Tambora.

            There are several basaltic-andesite volcanoes located in subduction zones that have produced explosive ignimbrite eruptions. For example Okmok did a 50 km3 ignimbrite 2000 years ago that is said to be basaltic, although it is probably a bit more silicic than mid-ocean ridge basalts. Yasur, Tofua, Gaua are other examples of volcanoes which have done powerful ignimbrite eruptions of basaltic-andesite composition.

            The only case of a gas-poor basalt ignimbrite I know of is the final part of the Halarauður eruption of Krafla. It is one of the weirdest eruptions I’ve seen which erupted every composition of the tholeiitic series, starting with rhyolite, then dacite, andesite, basaltic-andesite and ending with basalt. The upper part of the ignimbrite resembles a lava flow. This is why basaltic ignimbrites might look very similar to lava flows and be difficult to find:


          • “Emplacement of welded (mostly lava-like) basaltic ignimbrites
            in the final stages of the Halarauður event reflects the unusually vigorous venting of gaspoor basaltic magma that was driven through a mature, highly dilated caldera fault system by the subsiding chamber roof.”

          • That ignimbrite at Krafla almost sounds like it was an actual lava flow just one erupted sideways with great velocity. Those big collapses of the cone on La Palma, where it fell down as a solid looking slide but then began flowing away as a lava flow sound very similar to this.

            I kind of imagine it the same as if a bucket is tipped over the water flows faster than it would on its own otherwise, because Krafla basalt is too fluid and gas poor to properly explode. Maybe it was similar to some of the taller fountains from Fagradalsfjall with all the high speed spatter flows except really huge.

    • Hmm . . . I’ve always wondered about the Ngorongoro Crater in Tanzania. What is the concensus (if there is any) about how it was formed?

      • It was like an oversized Tambora .. over 500 km3 was ejected

      • We made it part of our series on supereruptions. It formed in the rift valley but nowadays is outside of it.

      • Ngorongoro Crater is still on an active rift valley .. below is rift Lake Eyasi and above is rift Lake Natron

        The eruption happened
        2 million years ago, pyroclastic flows flowing over a landscape with healthy mammal megafauna.

        The ashcloud must have covered most of East Africa

        Homo Habilis and probaly Homo Erectus and the australopithecus saw that massive event togther as they coexisted for some time.

        Many 100 s of cubic kilometers where ejected must have been a crazy sight .. looks like the Ngorongoro Crater is an oversized Mazama like event.

        • This will please you: I read in a paper (forget which one) that LIP are supposed to have preceded spreading. So at some point in the next 10 million years there might be an LIP next to the rift before the ocean enters into the rift.
          Thinking of CAMP, NAIP, the South Atlantic and the Deccan Traps it is possible.

          This won’t please you: We won’t be here any more.

          • Would probably be smaller than the heavy hitter flood basalts of the Mesozoic, no? Africa is much smaller than Pangea, lot smaller lid on the pressure cooker. Still, even a small flood basalt is incredible, IE Colombia River.

    • I wonder if the caldera floor will eventually turn into a field of rootless spatter cones like it was in 1823-1840:

    • I guess it was outgassing through a new crack in the surface. It was only visible at night and the location is in the outflow channel, not in the crater. But it is not dead yet. Who would have thought the old cone to have had so much lava in him?

  13. It’s incredibly windy today, worse than Storm Arwen was and seems to have been going on all morning.
    I’ve already lost some MORE tiles…was expensive enough for an emergency repair the other week.

    • Pantiles (concrete)?
      These days they all have to be fixed down, which is daft where I live as on five houses with identical roofs built 1963, not a single tile has ever been lost.

      • Live on an Island on a rock directly at the sea. Every tile is nailed. Tonight we expect 35 m/s. Always exciting to see what damage I have to repair when it is over!

      • Yes, except mine aren’t fixed. I had some re-pointing done and some tiles replaced lately and it cost a fortune for what was actually repaired. Roofer said everyone in these streets has regular problems.

        • Must be seriously windy, the interlocking tiles on this house would be really hard to shift except perhaps the gable edge. Houses have had walls sucked out, ordinary clay tiles gone, so sometimes its windy.

    • Is no one going to talk about the beast that is Taal?! “Oh my god! Fagradal is glowing! Kilauea is erupting for the 100th time in a 100 years!”
      Taal, currently under a protracted intrusion that could mobilize a large volume of magma and cause a VEI4+ eruption gets cricket chirps? Is no one going to address the fact that the entire system is inflating and Phivolcs has neglected to mention this important fact in their reports? There has been background tremor for a year and no one has seriously asked what’s going on?
      You’d figure a beast would get a glance

      • I have been talking about Taal 🙂

        In short it is better if it is inflating, then the magma will mostly displace the water in an eruption due to pressure, and the worst will be a series of tall fountains and maybe plinian eruptions, but no serious immediate danger beyond Volcano Island, something manageable. Deflation could lead to another Hunga Tonga, but on land…
        Deflation in wet volcanoes is priming the red button, and the magma is not the bit to worry about, no matter if you have pure molten quartz or the hottest komatiite, it is only acting as a heat source to make supercritical water.

        So yeah basically if Taal is inflating that is not ideal but is by far the better outcome…

        • It’s not the inflation or deflation alone that brings the concern, it’s the cause and the cause is concerning. If the intrusion makes just 1% of total reservoir erupt, that’s a VEI 6.

          • I think you might be using the model proposed for that of large rhyolitic calderas, where new magma intrudes and destabilises the system, triggering a runaway eruption. Taal is not rhyolitic, and seems at least since the early Holocene it has only erupted basalt, so this recharge likely is not going to do anything, and if it did then it would be 10 km3 of basalt. Might be pretty violent, like an Etnean proxysm that lasts for weeks, and Volcano Island would probably be a lot bigger afterwards, but Pinatubo v2 it would be not.

            I suggest Davidof in Alaska if you want a really big bang, it seems to be waking up after who knows how long asleep. Known products are rhyolitic, and most rhyolitic eruptions are big, so this is definitely one to keep a look out for.

          • Very curious to see what happens with Davidof. In all likelihood, nothing. But this second round of rather large quakes is interesting if nothing else.

            I can find very little info on it so anything you guys care to share about it is much appreciated.

  14. …again coming a bit back to the pressure wave 😉

    I finally found a graph of the pressure wave from the Tunguska Event (in E. A. Silber, “Infrasound observations of bright meteors: the fundamentals, 2018”; the graph is reproduced from an article from 1930), commonly thought to have been a ~30MT TNT total kinetic energy before atmosphere airburst from a small asteroid or cometary fragment. It was about 0.25mbar at the first pass in the UK. Again, scaling is of course uncertain, but this underscores the enormity of what we were witness to.

    • Great find, Dominik!

      So, a quarter of a millibar at approx 5600 KM (Tunkuska to London).

      Tunguska yield estimates range from 5 to 40 Megatons, and cluster around 15 to 20. They are quite problematic, because as we don’t know the altitude, so can’t realistically calculate yield from the ground damage pattern (Hence the wide range of estimates).

      So, IMHO what we need is the amplitude of the Hunga Tonga shockwave at around 5k to 6k distance. Hawaii is a fit for the low end of the scale, Perth for the high end (at almost 7k). I found the Perth (western Australia) data; 3.3 hPa. That translates to 3.3 millibar (Millibars convert to HPA at one to one; they are the same). So, at a bit more than the range from Tunguska to London, we have an amplitude about 12 times more.

      And it’s worth bearing in mind that amplitude-to-density isn’t a liner function (doubling the amplitude doubles the power). It’s not, it doesn’t double it, it squares it. Tripling the amplitude of a wave results in a nine-fold increase in power. 12 fold? 144 times the power. That can’t possibly be right, so I’ve messed up somewhere.

      However, Tunguska and Tsar Bomba are problematic ; both were air bursts. Hunga Tonga was a ground blast, at least to a degree. I’m thinking that the US Castle Bravo test, at 15 megatons and a surface detonation, might provide a better yardstick. So too would similar data for any US megaton-range surface test (So, Bikini and Enewetok),Unfortunately, I’ve only found one data point so far for pressure amplitude at distance for US pacific nuclear tests, a measurement in Tokyo at about 4000km range. It doesn’t list Castle Bravo, and the only megaton range detonation to does have record for looks to be Redwing Apache, 1.9 MT, July 8 1956 (listed on the table as VII (July) 10, because of travel time plus the dateline) That was .6 milibars, and I’m going to round up the MT from 1.9 to 2.0 because it’s an easier number to deal with.
      Table 1, page 107

      So, 2 MT at 4000km gives us .6mb. Hunga Tonga managed 3.3 at a roughly similar range. That’s an increase of 5.5 times the amplitude, so 30.25 times the power. So, even if Tunguska was at the lowest edge of the estimate range at 5 megatons, that’s make Hunga Tonga 151.25 megatons. That can’t be right, so either I messed up somewhere (likely) or the questionable table I linked shows poor data.

      Would anyone here have pressure amplitude data for any US pacific megaton or higher surface-level tests?

      • CJ, many sensible thoughts, I think! I do not really know how many people are interested in the energetics, but for sure I am. Not (only) because big numbers can be fascinating. We should never forget the catastrophe this brought upon the vicinity. Mainly because I think by understanding the energy reservoir that was tapped (plus timescales), models could be constrained.

        At the moment, in all we are doing here (and anyone else has published as far as I can see) there is an obvious loophole; it is relatively easy to calculate from the pressure wave the rough energy of the wave. Carl has done it here, others also. It seems a figure of about 50MT TNT is unavoidable. Comes directly from the energy needed to expand a sufficient volume of gas, and without that, no pressure wave.

        But that is not total energy. There is nothing in that that will hurl ash oder vapour to the stratosphere and beyond, there is no prescription for large-scale movement of tephra, potential landslides, erosion / blowing apart of the islands, and, very importantly, the long distance tsunami is not in it. Not relevant how exactly the tsunami was driven, the water waves carry a *lot* of energy.

        It is quite difficult to make such a calculation of the total energy budget. I am seriously lacking key data to even attempt it. Maybe someone has that data, or will have soon. Whatever the exact number will be, my feeling is it will be quite substantial.

        Because what we have been doing until now is comparing the pressure wave to events that do not really match (nuclear blast, asteroid impact), or where the energetics is also highly unclear (Krakatoa). As you said, we have no reason to think that the Hunga Tonga event had a similar ratio between total energy (58MT TNT) and fraction of that in the pressure wave (<40%) as Tsar Bomba. Depending on the answer to that, the total energy release of Hunga Tonga will be either larger, or very substantially larger than what went into the pressure wave alone.

        More data from ground level nuclear tests would still be interesting, of course!

  15. … and there is the answer to the low SO2. SO2 readily converts to H2SO4 when water is present. Converting early, while still in the troposphere, means that several orders of magnitudes of it does NOT make it to the stratosphere.

    Couple that with the relatively SO2 depleted roof material… it starts to make a LOT of sense.

    Yeah, we got off lucky.

    • Doesn’t we need SO3 for that if there isn’t vast oxygen around? I thought SO2 will first of all gain us sulfurous acid as opposed to sulfuric acid…
      Anyways, the SO2 has been captured early enough by either my or your suggestion, perhaps a mixture of both.

    • I’m not quite sure how the laws of physics would restrict H2SO4 aerosols to the troposphere while allowing H20 (clearly aerosils) to reach 55 km and the main column to ~35 km? Following the Maxwell-Boltzmann distribution even considering the equivalent of the microcanonical ensemble of Gibbs this needs to be measured.

      Have you seen any data on H2SO4?

  16. Just in case Kuwae was like this one and wasn’t a VEI 7 at all (in question anyway) and Changbaisan (Paekdu) is rescaled to a VEI 6 the we get new statistics, for sure:

    “And VEI-7’s are even harder to find. In the last 2000 years, we have suffered Tambora, possibly the 1452 eruption (cautiously attributed to Kuwae), Rinjani, Baekdu, Ilopongo (recently upgraded to VEI-7) and Taupo.”

    It would be an average of 500 years then.

      • My view, as i’ve argued for almost a decade on VC is that VEI-7 sized eruptions are likely under-represented and they occur more frequently than previously believed.

        You can generally get an idea of what the size of a previous eruption was by measuring the size of the caldera that was left as a result of the eruption. Since calderas represent displacement, there should theoretically be more magma that exited as a result of the eruption than the volume of the caldera itself.

        So when you look at a volcano like Tambora, which was a nice VEI-7, or even Rinjani/Samalas which formed a larger VEI-7 a few hundred years earlier but only left 3x3km and 3×7 km calderas, you wonder what the true eruption sizes of volcanoes like Okmok, Aniakchak (10×10 km each) or any of the many volcanoes that have eruption sizes estimated at VEI-6, yet have larger calderas from said eruptions than our previously mentioned indonesian volcanoes.

        Then there are other calderas that are enormous, but we just don’t have great records for on any time frame. A good example would be the island of Umboi, which is west of New Britain and north of Papua New Guinea. It sports a beautiful 17 x 11km caldera with a series of ring fault somma on the arc. These are more common than I would wager a lot of people realize.

        I would have to find my old work, but I believe my estimated probability of a VEI-7 eruption was revised to being approximately every 200-300 years, as opposed to the previously believed one in every 1000 years. That being said, there is likely a lot of fluctuation in that, and there could be some patterns of ice ages affecting eruption rates.

  17. Waiting for Carl’s Pangaea-hammer I am reading a bit and found a very good interview with
    Nakada Setsuya, Professor of volcanology, Earthquake Research Institute, University of Tokyo, specializing in volcanic geology and petrology, from 2015 with a list of volcanic eruptions in Japan from 1700 till today, three pages:

    Mount Tarumae, mentioned in interview:

    The mountain, together with other volcanoes like Fuppushi (pic) borders Caldera Lake Shikotsu, like most volcanic settings very pretty:

    • Looking at the list on page 2 is enlightening: These eruptions were all only VEI 4-5 and below, and yet, there is no eruption without deaths. Deaths always by debris avalanches, pyroclastic flows, gas and tsunami, 15.000 victims of Mount Unzen in 1792, probably corresponding to a lot more today, by earthquake, debris avalanche, tsunami. Message of the interview: The VEI is only a criterion to scale a volcano and says next to nothing about the loss of life or habitat.

    • So, whereas the VEI is really not that important concerning local damage including deaths – this also goes for scale – it is hugely important for global implications which lead me to a great piece (imho) by Tallis:

      I think it is very wise to mention Alban Hills and Epomeo.

      To Tallis himself – hope he sees it:
      I think there is one mistake in here:
      “Volcanic winter is one of the biggest threats to modern society and essentially a guaranteed event but has no respect within the populace. Large scale volcanic winter is something to be taken lightly. Please tell me what your candidates for a large scale volcanic winter.”
      I believe it should be:
      “is something NOT to be taken lightly”. Maybe VC should correct it.

      • Corr. for my thoughts: Taal instead of scale (right at the beginning). Thinking and writing makes these mistakes sometimes.

          • It is really good.
            Next to Epomeo there sits a witch on the ocean floor with an instable mind 😉


            Very shocking:
            “with extreme values exceeding 20 m in Basilicata and 15 m in southern Campania and north Calabria. Focusing on the Sicily coasts, one can see that they are partially protected by the Aeolian Islands, as stated above. However, for scenario (e), waves from 5 to 10 m affect the coast……

            Portions of these coasts are vastly populated, especially during the summer months. Nowadays, the lack of a tsunami warning system for landslide-induced waves in Italy makes these kinds of phenomena more dangerous.
            Furthermore, the social perception of tsunami risk in this region (see Gravina et al. 2019) and in the whole Mediterranean basin is overall very low, due to the time interval elapsed since historical hazardous events. These aspects together enhance the tsunami risk for a large part of the above-mentioned coasts.

            Finally, the worst-case scenario of failure of a 17.6-km3 mass (case (e)) shows the generation of a potentially catastrophic tsunami, with waves as high as 20 m reaching the coasts of Calabria and Sicily regions in about 20 min. This hypothetical result must not be intended in a hazard perspective but serves to depict the possible consequence of large collapses on a seamount in the Tyrrhenian basin.”

            Greetings from Marsili!
            Tsunamis from prospected mass failure on the Marsili submarine volcano flanks and hints for tsunami hazard evaluation, G.Galotti et al.

          • Volcanoes in the Mediterranean could produce the worst volcanic tsunamis in history. The combined variables of some big volcanoes near a lot of water, large population along the coast, and a lack of specially designed infrastructure is a bad recipe

  18. Skotmannsfell really going at it now, whole fault is active, it might get magmatic soon 🙂

      • I personally think Carl might have made the name up 🙂 but it is next to a mountain called Ok, which is a Pleistocene shield, maybe also an actual central volcano. Ok is usually considered to be a part of Presthnukur volcano, one of the two official central volcanoes under Langjokull, but in reality the tectonics of that area seem to be quite more complex than that.
        Out of the whole of the western volcanic line, including Reykjanes, only Hengill, Krysuvik and Svartsengi seem to possess active large volume magma chambers, allowing these volcanoes to do flood basalt eruptions (though of much smaller scale than those from Vatnajokull). Hengill also has some rhyolite, though maybe not any that is active. Seems the central volcanoes and shallow magma chambers under Langjokull are dead, only the deeper plumbing is active, which allows for voluminous shields but not rhyolite or fast basalt floods.

        I guess maybe whatever this activity is, it comes fro mthe deep plumbing of langjokull, but it is outside of a rift so there should be no long fissure or wandering vents, just a nice cluster of vents, first a lava geyser and then a shield, that will hopefuly last for decades 🙂

    • It is interesting to see the activity ranges from 11km down, to as close as 1.1km (99%ers). But we’re still short of tremor, and the drum plots still look ‘dry’. Watching closely…

      • I guess being realistic it will probably take a swarm of similar intensity to the one last year to even get an eruption, being this is virgin ground as far as Holocene activity goes. But then it is not a rift with pent up strain, so could be less than expected. Perhaps we are also witnessing the final ramp up and it will erupt by mid February 🙂

        • Isn’t it in the Western Volcanic Zone – the western branch of the MAR? Given that it has been less active than the eastern branch, how do we know there isn’t pent up strain?

          • It is, but not a rift zone of that area.

            But then it has not erupted in who knows how long so really its all guesswork here.

      • The reported depth of 1.1km for the shallow quakes seems to be a standard value set by the algorithm (we discussed this earlier). Note that the ‘quality’ value in the table at is mostly 90% or less for these. It is interesting however that those quakes (the blue ones) are located in a cluster southeast of the other quakes in that region.

  19. Also, maybe for Hector 🙂
    Kilauea eruptions from around 1800 to 1868, where activity was dominated by a massive rootless lava lake as it seems to be now too. Yellow lines are the shallow pathwways taken by the magma, red is the location of the active magma storage (conduits and magma chambers) and purple is the lava flows of that era.

    This lake was way bigger in volume than the lake we have now, but then also lower in elevation so less gravitational potential, already todays lake surface is likely at the same elevation as when the 1840 eruption happened, just the rest of the caldera has also filled in too since. Todays lake is also only a year old, where the 19th century lake probably began to form at least several years before the first flank breakouts occurred (Kealaalea flows, around 1810) and maybe 15 years before the first really voluminous breakout in 1823. If todays lake fills at the rate of the early 18th century as it seems it might be doing now, then the 2018 caldera will fill, and the lake surface will be near 1000 meters elevation and as much as 500 meters deep. I think that some point in maybe the next year or two, we will see a Mauna Iki-type eruption somewhere southwest of the caldera, and maybe later this decade a much faster eruption somewhere, hopefully not in Puna again. It will be very exiting for sure this next decade 🙂

    • Great map! I like it how you follow the Great Crack all the way to Halema’uma’u and also how you include the Koae Fault System.

      The only pathway lacking is that of the 1832 intrusion, but of course that one is a mystery. Accounts from that time mention how it cracked open the area to the east of the caldera and also how it opened cracks in the Puna district. I have never seen any mapped fracture systems that match those of 1832. I suspect though that it continued the Kilauea Iki fissure swarm to the east.

      Currently the pressure of the volcano low. The eruption continues to drain magma from the East Rift Zone, this is shown by the deflation downrift of Pu’u’o’o where the largest magma storage of the rift is located. The summit magma chamber has still not built up any pressure since the eruption. Therefore the lake will need to grow much more before Kilauea starts to build up pressure for a flank eruption. This could take as long as years.

      The elevation of the lava lake before the 1823 eruption is not known. But before the 1832 and 1840 events it had flooded the whole caldera, so it was quite high. Likely it stood higher than 1000 meters. Currently the floor of the caldera stands at 1080 meters, after 1840 it was at 1020 meters and the lava lake before 1840 had probably stood at that height or above.

      • This is why I think it is likely that the lava lake will rise until it floods the whole 2018 caldera, but it will probably drain before overflowing onto the larger 1790 caldera. In this case we are looking into multiple years of continuous lava lake activity.

        • In effect the collapse caldera and lava lake is now acting as an excessively large conduit. I expect that the entry point is still the rift on the side a year ago, and not the bottom of the original hole, but it is hard to be sure. The DI events are in the lava lake, perhaps now that the lake has grown deep enough – that will be the depth to the inlet, if this is not at the bottom of the lake.

        • Lava effusion rate for this eruption so far, 45 million m3 in 117 days, or around 385,000 m3/day, of course on average. Extrapolating this out gives a total of 140 million m3/year rate, which is rather high and equivalent to 2/3 of the hotspot rate.

          To fill the 2018 caldera will take around 1 km3 of lava, so 7 years or so, which is sooner than I thought. I dont really expect it to be that quick but then if nothing changes it is entirely possible. So realistically we are looking at the 2018 caldera being entirely gone in 2030, either that or it is still there but so is a massive new flow.

          I am quite exited to see a live view of the whole lake surface just falling down into the depths as it drains out somewhere, the re-exposed downdropped blocks turning to massive lava falls as the crust drains down. I think the whole sky will light up bright as the crust is destroyed and founders, while the whole lake drains in a day, all 1 km3 of it.

      • The maps of Kilauea made in 1980 do include cracks that are far east of but point at Kilauea Iki, and are too far north to align to any of the normal ERZ fissure swarms. There are no cracks actually close to Kilauea Iki itself though, so hard to confirm. I am wondering if that drain was the product of multiple large ERZ intrusions, and maybe eruption offshore.

        I was not aware the early 19th century caldera floor was so high, it was empty in 1794, but producing flank eruptions before 1815, if it filled to 900+ m elevation in under 20 years that is going on 5 km3 of lava if not more, or 1.2 km3 every 5 years. Also a lava lake as big as 2 Holuhrauns, that is crazy. Still, it seems the supply rate has increased in the last month, still awaiting the next measurement but it could well be that those deeper summit quakes did mean something after all.

        • I think it was filling up continuously up until 1823, and then it may have reached a height of ~1000 m because I do not see any reason the level should have been lower than in the 1832 and 1840 drainings. Both the 1823 and 1832 draining events must have been very large, my best guess is somewhere around 1 km3. In 1823 the eruption was subaerial but most of the volume must have been discharged into the sea. 1832 possibly erupted underwater, most likely in the Puna Ridge.

          • I always did think the 1823 eruption must have been very big and mostly ended up in the ocean, Nyiragongo lava floods usually are around 1/4 of the collapse volume erupting at a minimum, but the caldera that William Ellis saw in 1823 was huge yet estimates of the 1823 flow are barely anything significant, and I cant imagine a shallow intrusion even 30 km long would be able to take 1 km3 of lava away. Just looking at the flow, it is obvious it poured into the ocean quite completely, there is no lava delta really it is a sheet flow.

            I guess we are probably going to see for ourselves soon. I did see that a few days ago the deflation on the ERZ reversed briefly, so seems there was a pulse of magma, coincident with the probable formation of the open conduit.

    • I should say that I do not think that the Kamakaia and Kealaalea eruptions took place after 1790. There was one publication arguing that these eruptions were from after 1790. It was said that the lava flows were overlying ash deposits from 1790. However there were also explosive eruption in the 16th century that were phreatomagmatic too, and I think they may have been confused with those.

      When William Ellis mentioned in 1790 that the locals had observed multiple eruptions taking place near the coast since 1790 he may have included not only the 1823 eruption of Kilauea, but also to the last eruptions of Hualalai, and maybe the Manuka lava flow of Mauna Loa. After all it is likely hawaiians would have attributed eruptions anywhere in the island to Pele, and wouldn’t know how to distinguish to which volcano each flank eruption belonged.

      I’ve seen the paleomagnetism of Kealaalea lava flows and it is clearly from an earlier age. It is also very obvious when looking at it in Google Earth. The colour of the flows is very dull compared to the 1823, so it must have erupted sometime 1500-1700 or so.

      The last Kamakaia eruption does have a paleomagnetism that matches with a ~1800 age. However the eruption is very unlike what I would expect from this time. There was a gigantic lava lake at the summit, and the Kamakaia eruption took place at 800 meters so that it should have been a major flood of lava (like 1823 and 1840), and not the normal-sized, slow eruption that Kamakaia was. I think it is more likely to have erupted a short time before 1790. I’m not as certain though as I’m with Kealaalea and maybe it is actually post-1790.

      • Kamakaia was sort of a weird eruption though, being more andesitic like fissure 17, the connection to the summit might have been poor so when the fresh basalt erupted it was only slow. Or maybe it was erupted before the lake was high enough to give a kick, or even before the lake was properly formed. The initial flow from Kamakaia Uka was a quite substantial a’a flow, which is mostly simple and flowed as far as 7 km, so would seem to have been fairly high rate. Probably was a moderate fountaining eruption, maybe a lot like a flank cone on Etna,

        Maybe eruptions like that are also relatively independant of the summit like those in the LERZ, happening from gradual buildup of pressure from an open but weak connection, and in this case too there is no option to form a better connection so it remains small scale volcanism. Seems cones form here quite consistently, there are some that are probably going back nearly 800 years and then some that are only 200 years old or so, I do wonder if we are due another, especially after that intrusion last August which went right up to this area. It looks like the last eruption was quite long in the making, with a number of tiny eruptions in the same area before the main flow.

        I would at least expect we see some SWRZ eruptions in the near future after the lake is high enough. That is good, the area is not inhabited and rather easily accessible, and very visible from a major highway.

    • I have also done some maps lately. I stumbled upon a catalogue of Hawaii relocated earthquakes. The earthquakes are located with incredible precision. It goes back to 1986 so unfortunately there aren’t that many intrusions included. There were few dike intrusions after 1983, given that most of the magma was just coming out through Pu’u’o’o. I like Kilauea when it goes intrusion mode, like in 1960-1969 or in 1975-1983. But is pretty cool anyways:

      This is a map of earthquakes the upper rifts, including the two rift conduits which are perfectly visible:

      • Seems the conduit shows up well where it has to go at an angle to the direction of spreading, after Mauna Ulu it is pretty well silent only showing its extent through deformation.

  20. NASA published satellite images of Tongatapu taken before and after the Hunga Tonga eruption:

    Clearly showing the ash deposits that cover most of the island. Even the tsunami damage could be visualized in a separate approach:

  21. The longer Taal goes without eruption the worse it could get so personally I wouldn’t mind another VEI4 burp provided there was ample warning and they evacuated everwhere inside the old caldera. A ring dyke eruption will happen eventually but let’s have it in 5000 years time when humanity is extinct aye?

    • Let’s have the eruption cause the extinction of humanity!

        • Tallis apears to be volcanology’s Hannibal Lector! For sure have thr chianti ready when the Campi Fleigri blows.

          • Well, if you’re planning to go the Hannibal Lector route and have some Chianti with a Campi Flegrei eruption, then I suggest to buy it now as Tuscany (the source of true Chianti) would be hard hit by a major eruption:

        • Tallis! How can you say that?. I haven’t finished my book yet. I’m still trying to get published. I don’t want to be wiped out by a volcano. Not that it is easy in the UK, anyway.
          (Anyone checked on the Borrowdale Volcanics, recently?)

          • I can’t wait anymore! I need my volcanic fix, I am tired of looking at studies describing caldera-forming eruptions and I’m tired of living among humanity. As a way to appease my hatred of this world and gaining the stimulation I’ve been wanting for years, a catastrophic volcanic eruption and winter are on the top of my list of desired events

      • You must have gotten up on the wrong foot yesterday, or something is bugging you.

        Imagine: We wouldn’t be here anymore. The only being ever that is able to understand things, is asking, doing research, writing everything down (including some rot), is being witness and, above all, admires earth and the cosmos, would be gone. The only human being who can say: That is beautiful (animals might feel it sometimes). The only witness of the greatness and beauty of things would be gone. Future Einsteins or Mozarts or Gershwins or Constables and Turners wouldn’t exist. Or Halldor Laxnesses – not to forget Iceland. The buildings would lie shattered in ruins, wind and rain would destroy pictures and books and notes.

        It would become very cold and then probably very warm. The dinosaurs might return in another form. Nothing against dinosaurs, but their purpose was eating and giving birth. As they became too huge they might have eaten up all plants, just like deer and elephants when there are too many of them.

        I agree that many things seem rotten, but one is not: That we are the chronists. Only the human being writes a diary for earth. Only the human being is able to admire the miracle of it.
        Some – to be admitted – tended to cannibalism and infanticide in famines. But others certainly reached out and helped. It is a being which would be called Janus-faced.

        Aside from that I do definitely not believe that the Dinosaurs i.e. would have died out because of the Deccan traps alone. It was Chixculub. Volcanoes don’t take 100 percent down. And while they can take down they are fertile ground for new life.
        Grow up.

        • Not to forget the others, the ones who grow food, the ones who do landscaping. Imagine a world without them. It would look like an overgrown garden soon with Japanese knotwood and snails. No charme in your idea. Better live with the dark side of the human being and see the bright side.

    • That channel really turns into a raging river now when the lake fills up. I wish we could get some idea of the flow rate at the start of these episodes, but it must be pretty high at times.

    • EpicLava is live on facebook viewing the flow right now, looks like a white water rapid from hell 🙂

  22. How to understand the behavior of the La Palma LP05 GPS deformation signal?

    • it has not moved much at all on the first graoh – so it has not gone north or south, on the scond graph it has also not moved much, so has not moved east or west much, the third graph shows up (and down) motion on the gps – that looks like it has been moving around a bit more – but looks to have dropped by about 100 millimeters (10cm) in the last 2 weeks

    • What have the other stations done?

      From memory the stations showing most deformation associated with the eruption were LP03 and LP06.

    • Probably will not see anything on La Palma again for decades, it isnt its style to erupt multiple times in a short period. This eruption was also the biggest there is a long time, i think in the end well over 0.3 km3 of lava, twice as big as the 1949 and 1971 eruptions combined. If it erupts again before 2050 I will be surprised.

      • I expected more a new “unrest” with turn to a eruption on Tenerife. That has overpast the time for a event on that island and the clock has runing.

  23. Well, Hawaii trip is officially confirmed, lets hope the eruption keeps it up until April and that it doesnt decide to go a week long pause…

    At the current rate of eruption, 3 months of effusion is going to add maybe another 35 million m3 of lava to the lake, so it is probably going to be over 50% more voluminous than it is now, or 130 million m3 total since Dec 2020. That should be enough to get it quite well int oview from most vantage points 🙂

    • I visited many times during the Puu Oo eruption and got to see the active pahoehoe closeup

  24. Maybe I will get lucky and a shallow flank vent opens southwest of Halemaumau, so I can see it up close too 🙂
    I think the chance of that in the next 3 months is very low though…

    • You should move there!
      But its very difficult with jobs and healthcare on the Big Island, althrough the small town feel is absoultely lovely, and specialy the Kailua Kona side, For me it will be Iceland.. an easier goal

      Still the Big Island is my favorite place

  25. Probably a bit slow to make this comment, but my first thoughts when seeing this eruption was primarily a water-driven event is that it adds great validation towards putting Iwo Jima at the top of the VC decade volcano list.

  26. Also, another passing thought that comes from the Hunga Tonga eruption is that one volcano that is far more dangerous than most would understand is the Ata caldera system coming from Kyushu.

    I say that not only because it’s not understood that it’s potentially a highly explosive volcano in a region prone to very large VEI-7 eruptions, but also the fact that there has been little to no thoughts on how a large eruption from this system would likely send tsunamis out into the east China sea, with Shanghai being an enormous population zone that would potentially be in a direct path of a potential tsunami.

    I suppose that my line of thought is that if Iwo Jima poses as a extremely dangerous tsunami threat, then the Ata system should qualify just as well. Any collapse or large eruption initiating from where the more recent historical eruptions have occurred at the Kaimondake cone would be right in the area needed to send waves towards all the wrong places.

    • I’m also thinking about the rapidly growing submarine volcano near Mayotte wondering how stable that edifice might be, growing so fast. This concerning a tsunami there.

  27. From Carl’s backyard:

    Mesoamerican Reef (Cancun to Honduras), Spendid Toadfish

    Unfortunately this guy is feeding there as well:

    • He has my sympathy. I’ve got a drainage problem too.

      • 😉
        You know what. He must be God. He survived Chixculub together with the shark (their ancestors).

    • Jeez! Nobody warned us about them on the Belizian reefs!
      PS Best first place for a foreign holidat is Belize, sea, (reefs, sharks/rays/tyrtles/manatee/coral), wildlife (amazing birds, particularly in season at Crooked Tree), Mayan temples of several types and sizes, power boating down new river, caves (just so many amazing caves), ziplining etc, ATM (look it up) and the food isn’t bad. Only thing lacking is total absence of volcanoes of any sort.

      • Sounds great. You must have been there. For volcanoes I recommend a combi-trip to Belize+Mexico or Belize+Guatemala. The volcanoes though must be under the reef. The Caribbean Plate: Old IP.

        • There is more than enough to do in 2 weeks in Belize, and Guatamala volcanoes etc probably deserve two weeks too. Never a fan of trying to cover too much in one country and missing out on great things. I wouldn’t have missed ATM for anything for example.

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