Ring dyke formation on Taal?

Lately Taal volcano has been showing unsettling signs of a possible imminent eruption, including high sulphur dioxide emissions, small steam-driven explosions, tremor, and somewhat surprisingly, deflation. I think that this is no conventional magma intrusion but rather a very rare type.

First of all I should briefly review what happened in 2020.

 

The events of 2020

Taal is a volcano located in Luzon, the largest of the Philippine Islands. It is also located within the Macolod Corridor, an area of tectonic extension that runs in a NE-SW direction. As such Taal is able to send dykes to the northeast, towards Laguna de Bay, which may have happened in 1749, and also to the southwest towards Balayan Bay, which happened in 1911, and in 2020.

Taal volcano forms an small island in the middle of a lake with a 2 kilometre wide caldera known as the Main Crater in the centre. It is however within a large caldera 20 kilometres across, and an even larger complex of dykes extending across the Macolod Corridor. From Wikimedia, Mike Gonzalez.

After several years of slow deflation, the volcano started to inflate in early 2019 leading to the eruption a year later. On January 12, 2020, the volcano snapped, columns of ash and fire fountains erupted from a fissure extending from the Main Crater to the northern slopes of the Volcano Island. A volume of 0.03 km3 of tephra was erupted.

Taal in eruption, 2020. From Wikimedia, by etrhamjr.

The main event was the dyke intrusion however. After the eruption, a large dyke started propagating southwestwardly, which cracked open the ground and produced numerous earthquakes. A later publication, that I will link at the end of the article, estimates that 0.53 km3 of magma were drained away from the storage of the volcano during the intrusion.

Volcanoes do not simply erupt, they also intrude a lot of magma underground, to make dykes, sills, layered intrusions, batholiths. They are the creators of new ocean crust. Therefore there are enormous magmatic structures that are invisible to the eye, hidden deep underground. The mountain is just the tip of the iceberg so to speak. This is exactly what happened in 2020. The enormous dyke will probably solidify into rock, accommodating some of the extension that takes place in the Macolod Corridor.

 

The aftermath

The amount of deflation that took place in 2020 was very large, 0.53 km3. It would take a long time to replenish this volume. For example in 2019 Taal inflated with an estimated 0.045 km3 of magma. At such a rate it would take 12 years to refill the deflation of 2020, and considering that the inflation of 2019 represents a surge far above the long term supply, then it would take much longer probably.

Taal after the 2020 eruption, from NASA.

It seems highly unlikely that Taal could refill and reach overpressure so soon, so that the explanation for the current unrest may lie elsewhere.

The current unrest extends all the way back to the 2020 events really. The volcano has been steaming ever since. The crater lake inside the 2-kilometre wide Main Crater has been continuously acidificating, probably due to the sulphur dioxide emissions.

The situation started to escalate rapidly in March 2021 with sulphur dioxide emissions that went over 1000 tonnes/day. Tremor, long period earthquakes, steaming, and recently steam explosions, are signs that something is wrong under the volcano and escalating. Sulphur dioxide emissions reached 22,628 tonnes/day on July 4 which is extraordinarily high for a non-erupting volcano.

PHIVOLCS also reports something quite unusual:

“Based on ground deformation parameters from electronic tilt, continuous GPS and InSAR monitoring, Taal Volcano Island has begun deflating in April 2021 while the Taal region continues to undergo very slow extension since 2020.”

I wish there was more information regarding the deformation, cause I find this statement quite enigmatic. It doesn’t fit well with the more conventional forms of intrusion. Typical dykes can produce inflation around the intrusion, and deflation around the magma chamber feeding it. However dykes also produce a lot of volcano-tectonic earthquakes and cracks, and I don’t see any clear signs of this happening right now. A sill usually produces one elliptical area of inflation which doesn’t fit either. And also typical dykes or sills require overpressure which is unlikely to have been reached so soon after the 2020 draining.

One possibility is that magma is melting its way upwards making a pipe shaped conduit, a plug, like lava lakes or domes, but I don’t see much reason for any deflation to take place in such a situation though.

There is one rare type of intrusion that could perhaps fit the current situation better than the others, a ring dyke.

 

Ring dykes

This is a variety of magma intrusion that takes place along the edge of a caldera in a ring-like shape. There are two varieties.

When the roof of magma chamber is pushed up the dykes can intrude with an inward dip. The volcanoes of Galapagos do this a lot. They commonly erupt from ring fissures just outside the edge of a caldera. They dip inward towards the magma chamber under the caldera.

Schematic drawing I’ve made of ring dyke intrusions around an uplifting or collapsing block.

However the roof of the magma chamber can also drop down, and sometimes collapse like a piston, here a dyke can form that is vertical or outward dipping. This a much rarer situation. The best known example is the Loch Bà ring dyke, in Scotland. “The finest ring dyke known to science”.

Scotland has several ancient volcanoes that date back to the initial opening of the North Atlantic 60 million years ago. These volcanoes have been eroded down to their ancient magma chambers thus showing a section the interior of the otherwise invisible and unknown internal structure of volcanoes. One of these is the volcano of Mull Island which contains the Loch Bà ring dyke. It is a truly massive intrusion that is up to 400 meters thick! And much thicker ring dykes, over 1 km, are known elsewhere.  A normal dyke is only 1-4 meters thick or so. The Loch Bà intrusion extends almost all round the 8 kilometre diameter caldera, and formed when it collapsed down by several hundred meters.

The interior of a volcano, of the Mull volcano. A central magma chamber consists of granite and layered gabbros. A cone sheet surrounds the magma chamber, made of concentric dykes/sills which dip towards the centre. There are also radiating dykes, not shown, and the Loch Ba ring dyke around the central magma chamber. From the British Geologic Survey, image found here.

Why could this be happening at Taal? The 2020 draining could have made the roof of the magma chamber under the Main Crater unstable, thus providing a trigger for the formation of a ring dyke. The Main Crater itself may have collapsed in earlier historic times, in 1754, when it is briefly stated in one of the reports that the volcano suffered a tremendous erosion in its elevation, although without more information this statement is rather ambiguous. In 1911 the Main Crater also deepened and the Crater Lake formed, however the volume lost can be easily explained by excavation during the enormous steam explosion that took place back then.

A ring dyke could explain the contradictory signs, that the Volcano Island is deflating but at the same time magma intruding. It could also explain the extremely high sulphur dioxide emissions of up to 22,600 tonnes/day, because ring dyke intrusions are often enormous.

The current situation may also be mirroring the events of 1749-1754. A large dyke intrusion, towards the northeast from Taal, took place in 1749, with fissure eruptions inside the larger caldera, and with the formation of cracks and grabens all the way to Laguna de Bay. It was followed by some years of strong steaming until the major eruption of 1754, which lasted 7 months and had multiple episodes of eruption of varying intensity and style.

The two eruptions of 1749 and 1754 seem somehow related, one possible explanation is that the drainage during the initial event led to the roof of the magma chamber starting to subside, which over time evolved into ring dyke intrusion and the major eruption of 1754.

It does seem worthy of consideration that this is happening right now. Confirmation that such an intrusion is taking place would be if an arcuate fissure opens up along the sides of the Main Crater, or if caldera collapse takes place, particularly if collapse events are detected, earthquakes in which the roof of the chamber suddenly drops.

I should note that if any caldera collapse takes place it will be related to the Main Crater which is a 2 km wide structure, a very small caldera. The larger 20-12 kilometre caldera seems to be inactive, the magma chamber that once existed underneath may have been destroyed during the collapse, and it is unclear whether it exists anymore or not, and I would guess it no longer does.  However even the smallest caldera is capable of terrible destruction. Caldera collapses bring out the worst face of a volcano.

If a ring dyke intrusion is taking place it may not necessarily lead to a major eruption, intrusions do not always lead to eruptions and the same thing perhaps applies to ring dykes, although not much is known about their behaviour.

Fire and water eruptions

When I did my Big Basalt Blasts series of articles, ring dykes may have been the missing piece in the theory that I was trying to put together. Some of the eruptions that I covered show signs of being related to the ring structures of the caldera, in particular the eruptions of Mijakeyima in 2000, Askja 1875, and Kilauea in 1790, which erupted, and/or degassed intensely, along ring fractures.

A ring dyke can explain the high sulphur dioxide emissions of Mijakeyima that lasted a few years and at their peak reached up to 50,000 tonnes/day. The massive size of the intrusion could also provide enormous amounts of heat to the hydrothermal system and trigger giant steam explosions. The ring dyke itself might drive magmatic eruptions, particularly when the roof of the chamber collapses and pushes magma up the dyke, nucleates gas bubbles, makes the magma fizzy, light, and explosive.

The basaltic explosive eruptions of Kilauea and Masaya, that I talked about in the Big Basalt Blasts series, often have such sharp contrasts between hydromagmatic and magmatic styles. Deposits are often made of alternating layers of greyish mud, and black scoria/pumice. The 1754 eruption of Taal was also this way. If Taal does go for a major eruption it is possible that we will see such hydromagmatic-magmatic episodicity show up.

 

Conclusion

The current unrest of Taal is somewhat unusual in that it combines deflation with extremely high SO2 emissions. One possibility is that a ring dyke intrusion is taking place together with subsidence of the roof above the central magma chamber of Taal

Even if such an intrusion is taking place it would be hard to known whether the situation will gradually calm down with nothing serious happening, or whether it will progress into a major explosive eruption like that of 1754.

PHIVOLCS is already reporting damage to crops and throat irritation due to the high SO2 emissions which are creating acid rain and volcanic fog. The situation is already becoming quite problematic. If Taal does go into a major eruption there will also be the major hazards of pyroclastic flows (base surges), which are like a breath of hell, that tears down trees and houses and kills almost every living being unfortunate enough to be found on their path, and there may also be tsunamis on the lake, volcanic bombs, and copious showers of pumice, ash, and mud.

Volcanoes are not friendly neighbours, and much less Taal.

 

Taal devastation, 1911 eruption. The National geographic magazine. 1912.

 

Various links

The 2020 Eruption and Large Lateral Dike Emplacement at Taal Volcano, Philippines: Insights From Satellite Radar Data:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2021GL092803

Some of Taal’s eruption history, particularly 1749, 1754 and 1911:

https://archive.org/details/eruptionoftaalvo00philrich/mode/2up

https://www.researchgate.net/publication/277950292_Nuevas_fuentes_para_el_estudio_de_la_erupcion_del_volcan_de_Taal_en_1754

Big Basalt Blasts series I:

 

 

288 thoughts on “Ring dyke formation on Taal?

  1. I like the mix as it is on this site. The Dragons and boss do a wonderful job.

    Anyway, time tends to erase memories. It’s easy to forget the long observations and comment sections devoted to Bob at El Hierro in the Canaries. To forget the weeks looking at Bali’s Gunung Agung. The months watching the outpourings in Kilauea. Not to mention Krakatoa and the recent troubles at Niragongo. Or to go back to this blog’s first festival of magma at Eyjafjallajokull.

    We like watching volcanoes doing stuff. This new Icelandic volcano is not only doing stuff for a long time, it is also quite different to other Icelandic eruptions. It’s the rebirth of Reykjavik peninsula volcanic activity. We might be witnessing something that has not happened in modern human times: the birth of a sizeable shield volcano. All on camera, too. So it’s natural to blather on about it whilst at the same time enjoying new articles by contributors. There’s plenty of room for comments on all sorts of things in the general discussion.

    This blog is perfect. And we have a nice bar for other discussions. Mine’s a pint, please.

  2. I’d be lost if it was all heavy technical info here. The blogs are a lovely mix of tech, teach and talk and it’s always great to be able to ask a question here and have it answered without judgement or mockery. Someday I’ll get up the courage to ask why the earth’s crust doesn’t start sagging underneath where the magma is coming out and leaving a hollow that is top-heavy with the erupted lava. I saw someone ask that question on Twitter once and they were dragged/roasted as the kids say now, by people too old for that carry-on. I bet if I asked it here somebody would take the time to explain.

    I think it’s a fabulous blog and if it became too technical and serious I’d have no place here and I think there are many more like me. 🙂

    • Thank you, on behalf of all commenters, posters and dragons. And that is not a trivial question to answer. Probably best to start at the opposite end: what makes the earth rise before an eruption? It is a post called ‘Up. And now we may need a post called ‘Down’ as well.

      https://www.volcanocafe.org/up/

      • Thanks a million, Albert. I’ll await “Down” with lots of interest but in the meantime will read “Up”.

      • The blog entry was very informative and easy to understand but most of all I loved your wonderful humour with the newspapers/media and countries. So so funny and very true to life. Thank you. I look forward to “Down”.

  3. Kilauea has recovered almost 25cm in width since the 2020 eruption. Before that eruption it was on a trend of slow increase. If I extrapolate that trend, Kilauea has just reach where it would have been without the 2020 eruption. We can call that recovery. Of course it should be seen in perspective. In the 2018 eruption it lost 2.5 meters in width, and even now it is still down by 1.5 meters compared to before that eruption. At the current rate of expansion, it will be back to its old size by 2025.

    • It is sometimes easy to forget the eruption only ended 2 months ago, and we are already expecting another. At this rate I think the 2018 caldera could well fill entirely by your date of 2025, though having such a massive volume of molten lava sitting somewhere is sure to see a catastrophic nyiragongan eruption take place, like in 1823, or 1832.

  4. Please continue. One way or another.
    I am an office clerk with practically no knowledge of English / volcanology and I have no problem reading VC every day for many years (I help myself with a auto transate😶)
    You write so beautifully and easily.
    I learn so much.
    The proposal to divide the talks into volcanoes doesn’t seem so bad to me.
    Thanks 1000x and keep going

    • Thanks for your comment- you have gone to alot to keep up and learn,I admire that! Cheers

  5. Long time reader, first time poster.
    Loved volcanoes since I saw the news footage of the Heimaey eruption when I was 8, always wanted to be a volcanologist but it never happened (life got in the way). Thanks to the internet and this page I’m aware of what our planet is up to and is capable of, I have a very basic knowledge through reading the many books I’ve acquired but the posts on here are amazing and I have learnt so much from Albert, Carl, Hector and all who contribute here. Sorry it’s a bit of a ramble but just wanted to say thanks and keep on keeping on, it’s much appreciated.

    • Not a long time reader, hardly a first time poster, but totally relate to your comment, Jem, and many of those above (greetings Clive and Gabrielle). Without the technical articles, the site would be impoverished. Without the enthusiasm of the eruption watchers, the site would be improverished. The largely self-enforced “play nice” rule here binds the whole thing together. Kind of lovely actually.

      As an aside, I’ve been wondering about the novel (to me at least) use of the word “dragon”. From the context I more or less get the meaning, but is this a British-ism, or is it specific to this place?

      • We had some discussion on this among the dragons. It is an old tradition (i.e. we are talking ten years) and may be from the warning to behave: ‘Do not meddle in the affairs of dragons for you are crunchy and taste good with ketchup’. Traditions are easily started

  6. Iceland is quite a slow-moving train so I can understand the disgruntlement, but I still appreciate it’s power and beauty, and the fact that we are witnessing geological history real-time. Have to say the main things that draw me to this site are:

    The unanswered questions. The why, then when , the how. I like to try and understand how these geological processes work, how a volcano crops up where it ‘shouldn’t be’, why volcanoes can erupt different types and styles, what sets them off and creates them. The big ones. The unexpected ones. The still-to-be-formed ones.
    I’d also encompass some geology and astronomy in that.

    The fantastic articles that are written with wit, expansive knowledge, simplicity and flair. The jargon is usually quite easy to understand, and I feel as though I have a fair grasp of the mechanisms and inner workings by now (when combined with my Chemistry background of course).

    The friendly and extremely helpful community here. Combination of people like myself fascinated by mother nature and folk of expertise who are willing to share and explain their knowledge. I love seeing posts from people about something new and exciting, or a different take on a subject. All people from different backgrounds too.

    Took me a while to post on here, I’d snooped for a while lapping up articles, and did the same for a couple of years prior on Erik’s Eruptions blog too. But it felt welcome, especially now that I’m just about knowledgeable enough to contribute myself and have even made trips to see some volcanoes of late (Greece)!

    I would also like to contribute an article at some point on a volcano in Greece, but it’s been put off a while due to work and ongoing DIY/decorating. Might well be nearer the end of the year before I submit it to the dragonlords.

    • RE: “I would also like to contribute an article at some point on a volcano in Greece,..”

      You might be interested in reading Walter L. Friedrich’s “Fire in the Sea”-‘The Santorini Volcano: Natural History and the Legend of Atlantis’.

      I missed my shot at walking on that lava dome in 2020 due to the travel bans. Looking forward to that walk next June, Etna, and Vesuvius as well.

  7. Just had a small earthquake here in the Faroes, it’s not confirmed yet, but seems to have been due to the construction of a subsea tunnel a few km away, has happened before that their explosives have hit just the right spot for a shockwave to travel through the rock and make it felt in the surrounding area. Lasted perhaps 2-3 seconds, just strong enough so that if there was more coffee in the mug it might have sloshed over.

    • Ok it was from a rock quarry on the other side of the mountain, about six km in a straight line, big charge hitting the rock just in the right sweet spot.

  8. There has been some activity in the Skaftafell region during the past weeks. Even below – 10km.
    The region is between the East Volcanic Zone and Öraefi Volcanic Belt. Not much going on there regarding volcanic history I think.

    Someone knows if there is some kind of strike slip fracture zone between these volcanic zones?

      • Thanks.
        It is the area along the southern border of Vatnajökull.
        From the ERZ to Öraefajökull the arrows become longer gradually. So some stress is build up definitely.
        A fracture zone should be there, but is not very clearly defined as SISZ and Tjörnes.
        Far less earthquakes. A geological snapshot ofcourse, the data used in the map.

      • I took a screenshot of the quakes regeristered by IMO and mapped by Vatna, period 1995 – 2019.
        Looks not like a fracture zone (total amateur!).
        There is a concentration under de Sulujökull, perhaps pointing to crusts rebound after losing weight of ice. 2002 -2009 shows to be the most active periode. https://vatna.carto.com
        Rebound would have caused ongoing unrest through the years?

  9. Beautiful comments since I looked last yesterday. Wonderful people. Is it volcanoes that create such a lively yet warmhearted discussion? Ewesome.

  10. And lava has returned to the cone-that-shall-not-be-mentioned. It is not yet overflowing but lava is beginning to enter Meradalir, so there must still be an opening below the rim of the cone. It is interesting that these episodes build up slowly, but after some hours end very suddenly. I interpret that as starting from build-up from below, but ending from the top

    • Well, lava has started to come out of ‘you-know-who’ and is again flowing towards what’s left off ‘telemetry hill’:

      http://brunnur.vedur.is/myndir/listi/webcam_langihryggurN.html

      If this episode produces big flows they may overtop ‘telemetry hill’ and melt any equipment that may be left there. Amazing to think back how tall ‘telemetry hill’ was towering over the original cones and now it’s in danger of getting buried for good…

      • “The devourer of medium sized hilltops”….
        Yes, the change in 4 months is mind-boggling for being a tourist eruption!!
        Interesting to see where this ends.

        • eyðandi hæða

          I sort of like that. But since it’s gurgle… it also means destructive floors.

    • In the paper above by Wiley he describes quite precisly the move from the Western Rift Zone to the Eastern rift zone as the Eastern rift is propagating north and south (Surtsey). Besides he dares a guess about the Southern Icelandic Seismic Zone (SISZ). He suggests it move over to the American plate.
      So in the year 2525250 or so there might not be any active volcanism in the West including Reykjanes left, but if man is still alive they might still read this testimony. So I made my piece with it. We are watching s.th. unique I said. Bless the documentation. And these people here.

      • Lol, it takes a lot longer for volcanism to be dead in some region… That won’t happen in 500 years. The thing is it might be quiet as it will be waiting for it’s next cycle, but it will take a while for Reykjanes to die off, potentially a few million years. Heck yeah, even Snæfellsjökull is still active while in theory it should already be long dead.

        • It would be 2.525 250 years minus 2021 years. That’s not such a bad guess. It had to do with that famous song, otherwise I might have chosen 6 my to be on the safe side.

    • “cone-that-shall-not-be-mentioned”….That’s not the problem, on the contrary, the cone should definitely be mentioned at the beginning. In the pieces about Nyaragongo it used to happen that somebody said like “The lava in the cone is visible again”. I frankly didn’t know first which cone and which lava.
      And as I was then only looking for info about Nyaragongo I skipped those comments and only read authors and Jesper, of course. It would be very nice instead to become aware of not everybody having only Iceland in mind all the time, and threads help.

  11. Yes, i think Volcanocafe comment section could benefit from being a bit more structured. I too have Icelandic bias. I love Icelandic volcanoes more than anything, and I don’t think i would have gotten into volcanoes if it wasn’t for Iceland, so i get why it is interesting.

    But after three months of 90% of Reykjanes discussions, it’s a bit hard to scroll down to find anything about La soufrière or Taal volcanic activity or have some other discussion ongoing, so I think it is best to split up these activities. [Perhaps make a different section about ongoing events, like the Reykjanes one… and perhaps one about Taal unrest too.]

    • At the end of June, the Montserrat Volcano Observatory released a photo showing the absence of a new dome in the La Soufriere, St. Vincent, crater. Other than that, recent news is hard to find for that eruption.

      Maybe Samsung could offer them a webcam or two ;>)

      I dunno. While watching the unnamed Iceland volcano, I’ve also been happily following the discussions and links to Etna, Taal, and Nyiragongo. It’s all good stuff. Multi-threading works for me.

  12. I don’t like the lowering of the alert at Taal, while everything is quiet now, unrest at Taal has come in pulses over the last year, so larger escalations are still very possible and could come with little warning. Since we have 2 potential sources of a major eruption, it wouldn’t take much for things to go very wrong.

    • I think you are right. If the magma is draining still and also filling up the ring fault with a lot of magma, when eventually the caldera collapses it will pressurize the magma and make it erupt. It sounds like that happened in 1754, multiple collapses over a 7 month period, the lava fountaining out of the ring fault and through wet ground.

      • I suspect this is how VEI8s happen, except with rhyolite instead of basalt in the ring dyke.

        • actually very possible, Taupo is a rifting volcano, and I remember reading that Oruanui was triggered by rifting. Basically it is exactly the same thing only there would be some rhyolite at the top of the chamber, so magmatic explosion instead of needing water to do the damage.

        • I would guess this is also probably what happened at Kilauea during the last major caldera collapse, in the months after 1790. I think Hector will talk about it in his series so maybe I have it wrong, but Kilauea and Taal probably are both examples of volcanoes that have outward dipping ring faults, so that caldera collapse creates a ring dike and can therefore be accompanied by significant summit eruptions if the draining is big enough, for Taal being that it has a smaller active caldera this will be easier t otrigger I expect.

  13. Fagradalshraun is putting on quite a show tonight on the RUV Langihryggur cam. Continual fountaining sometimes to 100+m in the cone, spatter splashing onto the ramparts, and frequent overspills from the perched channel going to Meradalir, sometimes going toward the camera. A bunch of smaller flows have developed on the side of the levee facing the camera. The area around the cone has changed massively in the two weeks or so since it first sprang that leak.

  14. Presently beautiful viewing in Iceland! At a glance at the features of the cone/vent it does look like a shield volcano in the making.If I’m wrong so be it! If that’s the case we are damn luckly to watch this in real time.

    • It seems that the eruption rate when the lava is flowing is pretty much the same as before, but because it is now active only half the time the total eruption rate is half what it was (7 m3/s is the latest number, as of one week ago). There is speculation in the media that the eruption is reaching the end. It may be, but it does seem to have recovered a bit from the near-extinction two weeks ago. Whatever happens, my ideas about how volcanoes erupt will never quite be the same! Not everything is a Kilauea or Etna. The lack of a real magma chamber makes a big difference.

      • You asked me, Albert, two days ago whether there was any volcano I preferred reading about, and I said no.
        I analysed the index a little bit though and saw 104 pieces about Iceland and 24 pieces about Indonesia plus the Philippines. To be generous I should add 6 about New Zealand. Basically I consider the area more important plus Japan.
        Then also the bottom of the Pacific Ocean considering the long list of Japanese Tsunami and the Orphan Tsunami in the East around 1700.
        And then there is definitely not enough about the Azores and the Canaries, it says one.
        So, there’s a certain imbalance for sure. And I think the Ring of Fire with all the movement and subduction going on might be more important altogether. It’s certainly suspense from Kelud to Taal or Mayon to Toba.
        There’s only seven about South America. ?
        I appreciated the piece about water and Ceres, btw.
        But don’t worry I saw a few while browsing that I haven’t read yet.

        • I am interested in Hokkaido and the Philippines, maybe Central America too.
          Those places seem a bit understudied. Africa also understudied and yes, the Pacific floor.

          Remember those sailors that found themselves surrounded by a pumice raft a few years ago? Did they ever determine where that pumice raft came from? Because it was big.

          Understudied and the potential for large eruptions is what I find interesting, especially the “what was that mystery eruption back in 1345?” puzzles.

          • Yes, and s.th. else. The Pacific Ocean is basically a well functioning recycling system that Venus doesn’t have (any more?) All those deep trenches draw oldest crust back into the mantle. So it seems to me that the Pacific Ocean keeps Earth going.
            Mankind needs a recycling system like that instead of throwing plastic, oil and atomic waste into that jewel.
            It is the heir of Panthalassa and might be Earth’s motor. The marvel that Mars and Venus don’t seem to have. Venus seems to have suffocated under her volcanoes around 600 mya. I became one of its biggest fans and was never there. I was planning a voyage to the Colorado plateau and the West Coast and then was stopped by Covid. The Colorado Plateau is basically born on the bottom of the Pacific’s mother, Panthalassa, somewhere around the equator some 1,5-2Mrd. years ago.
            So, volcanoes are only one side of the coin. The other side seems to be the deep sea trench.

          • Basically the Pacific Ocean is a very different system. The Atlantic ocean and also the Indian Ocean are the heirs of Tethys, just the other way around. Tethys was horizontal. There is a lot of continental crust under the waters of the Atlantic, shelves, as there must have been under Tethys.
            The Pacific Ocean has next to null continental crust. And contrary to Albert I think it will not disappear because it was always there. It might still be the same old Panthalassa, just with different plates.
            And as there are spreading ridges in all oceans including the Pacific’s South East it must shrink. Otherwise – that’s what scientists discussed for a while – the globe would grow.
            As soon as the spreading ridges for some reason stop working like in the Tethys Ocean the Pacific Ocean would digest less and shrink less.
            So I believe that the Pacific Ocean with its ocean crust will always be there, just differ in size. But that’s contrary to what most people think at the moment. It would make some sense though.

          • Panthalassa was not around 1.5 to 2 million years ago. Closer to 250 million. And the Atlantic is heir to the Iapetus; the Indian Ocean, the Tethys.

          • Twisted One, I said Milliard. 1,5 to 2 Milliard in Europe – I used the European numbering system equal to American 1,5 to to Billion. I said 1500 to 2000 million years ago.
            I am in baby in volcanoes. But I wouldn’t be here or read about geology if I couldn’t handle numbers.

  15. Been away and so missed the ding-dong in the comments – I can see it might be disappointing to put up an interesting post on “volcano x” and for the x comments to be buried beneath Iceland stuff, much of it coming from non-geologists like me. I was a regular reader in the Holuhraun days then my attendance fell away.

    Some people are just volcano freaks without knowing much about dykes, sills or strike-slip faults. On Stromboli I became aware of people (usually male with family in tow) for whom every holiday means a new volcano – people who travel the world to see them.

    Maybe the Dragons could implement a feature by which comments could be tagged (by the commenter) with a volcano name or “General” or blank, perhaps from a dropdown list maintained by the Dragons (indeed the “Select Category” dropdown list would do)? Then when someone wants to see the Taal or Etna or Nyiragongo comments there could be a “Select Comments” dropdown box similar to the “Select Category” one.

    • It’s amazing to have these processes recorded in video from such a close distance.

  16. Tuesday
    27.07.2021 19:02:10 64.611 -17.491 0.1 km 3.3 99.0 3.7 km SSE of Bárðarbunga

    • https://volcano.oregonstate.edu/kaguyak

      This is also a possibility that it is Kaguyak instead. Or some other volcano in the Katmai neigbourhood (East Mageik).

      I also think Mount Dutton is a realistic candidate for a +-VEI 6 eruption in the future. It’s possible, it has the characsteristics, but I do not do intense study on the volcano of course, but it is one that didn’t blow yet i believe, while there was seismic unrest in the latest century.

    • The crater seems to be rather small for such a large event. Kaguyak’s large eruption was 4000 years too early

    • Mount Akutan is just not big enough. The caldera is 5km^2. It is only 1300 meters tall and that is an isolated point. The caldera is less than half the width of the cone and the cone proper starts well above sea level. It might have been about 2000m pre-eruption and the caldera isn’t that deep. A generous volume estimate would be 2.5 km^3. It would have been a low-end VEI 5 with minimal weather effects.

      There is a suspicious flat area about 4×4 km^2 to the southwest of the caldera. It has rims at the edges and might be a largely filled in caldera. That might be big enough for a VEI 6, but would be much, much too old. Mount Akutan might be the new center on the caldera edge after the big blow, that grew big enough in turn for its own caldera-forming eruption.

      • Iceland is very unlikely and the evidence for it is very thin. There were two major eruptions in sequence. Ilopongo is a likely contender for one but this has been disputed recently when its eruption was dated to a century too early. Read all about it: https://www.volcanocafe.org/apocalypse/

          • Brillant. I wonder how long you worked for that one. Two history sections, the Romans and the Maya, and the Maya Hiatus make Llopango a plausible culprit.
            That would not exclude Iceland for the first event, btw. You said though that Iceland is lacking local evidence.
            I’ll read the piece several times for sure, really great with lots of details.

            A few questions though: That flame over Gaul: Would it really be possible to see a say VEI 6-7 of Llopango from Italy? Second question related to the first: You mentioned the Azores: What about two eruptions? Third question, also related: Is it absolutely certain that Teide had no eruption before the one mentioned in the ninth century?

          • Roger of Wendover lived 800 years after the event. That is a long time. I think he is the only one who talks about a ‘flame’ covering the sky. Normally when reading such a description, you think ‘aurora’. It may have happened centuries away from the apocalypse

          • It occurred to me reading your piece. I have seen the Pacific Ocean, I forgot. I have been to Teotihuacán and near Mexico City somewhere and in Manzanillo. Funny. Teotihuacán and Popcatépetl were more impressive than the coast in Manzanillo, besides we were suffering from Montezuma’s revenge in Manzanillo. The people in a village nearby, 30 years ago, were extremely friendly. They gave us coffee with milk, and the milk came from Montezuma’s cows. They were poor but didn’t want any money for the coffee.

    • Cassiodorus’ report from 538:
      The sun’s rays were weak, and appears a “bluish” colour.
      At noon, no shadows from people were visible from people on the ground.
      The heat from the sun was feeble.
      The moon, even when full, is “empty of splendour”
      “A winter without storms, a spring without mildness, and a summer without heat”
      Prolonged frost and unseasonable drought
      The seasons “seem to be all jumbled up together”
      The sky is described as “blended with alien elements” just like cloudy weather, except prolonged. It is “stretched like a hide across the sky” and prevents the “true colours” of the sun and moon to be seen, nor the sun’s warmth.
      Frosts during harvest, which makes apples harden and grapes sour.
      The need to use stored food to last through the situation.
      Subsequent letters (no. 26 and 27) discuss plans to relieve a widespread famine.
      https://en.wikipedia.org/wiki/Extreme_weather_events_of_535-536

    • Maybe the video was released July 26, but the it was filmed much earlier, before the lava broke through the main exit channel from the cone to head north toward Meradalir.

    • SIL network has it at M5.2, but it’s listed at very low quality. Quite sizable signature on the drumplot, so it will probably end up around M5 once manually verified.

        • M4.5 now. Is this the final call?

          These quakes take place on the Bárðarbunga ring fault and give rise to peculiar waveforms due to the complex geometry involved. As such it’s common for quake magnitudes to be revised upon further investigation. The 50% initial quality measure by the automatic SIL network says it all really.

  17. No more pulses/gushers happening now. It seems that the weight of the degassed lava in the crater, which is now filled all the way up again, is inhibiting the gushers. Presumably the gas is unable to punch through it anymore.

  18. Screw the semi-deplorable pictures and videos I was looking at, if this signals an eruption, I’ll be happy.

      • Didn’t know you had bears there too 🙂

        Giggle translate:
        “There is now a great deal of volcanic eruption in Geldingadalur, which can be seen on a webcam mbl.is, although the force of the eruption is measured much smaller now than before.

        There was a massive corridor in the eruption last night until under three, according to Sig�r��ur �rmannsd�ttir, natural ization specialist.

        “We even saw a good bear and even a twist or glow outside in the Reykjanes peninsula. Then it fell down a little bit,” she said, adding that the eruption is still in good gear now and lava flows into Meradali.

        Previously lava also slipped into The Night Pasture, but the average lava flow has been declining and is only 60-65% of what was longest in May and June.”

  19. Tuesday
    27.07.2021 22:12:10 64.621 -17.358 1.5 km 4.5 99.0 8.4 km ESE of Bárðarbunga

    Tuesday
    27.07.2021 19:02:10 64.608 -17.500 0.1 km 3.9 99.0 3.9 km SSE of Bárðarbunga

  20. Hi all. Long time lurker and regular reader (pre “site theft” days), occasional poster, interested person who still doesn’t understand different rock types!

    Caught up on all the comments re the site format and have a few thoughts to those in the mix.

    I don’t mind the medley of comments as I’m generally interested and so quite like the stream of thoughts on the article post.

    What I want to avoid is needing to scan lots of different threads to find the latest comments. I rarely even go to the VC Bar.

    I love the articles by a mix of different people and appreciate that they and the topics will always be mostly closely related to writers biggest interests.

    As there are lots of different views here, does it sound like VC has matured to a point where a different forum format is needed?

    Do we need to remind or question ourselves about what this site is? Is it a blog posting site or a forum?

    The article plus post format works well as a kind of blog. If it were a forum for comments on lots of different topics it might look more like this (which is quite an old fashioned forum format) https://www.ukweatherworld.co.uk/forum/index.php

    On this site you have lots of threads on different topics and can also see them by more recent posting to see what is new. But you would lose the lovely article format.

    However we also have to remember this site is moderated by a few highly appreciated individuals doing this totally in their free time. So whatever works best for them needs to be considered. It can’t be loads more work for them.

    I suppose it also depends on how the dragons want this site to keep going as. If we are losing readers because there is not enough on other volcanos do we need to try and expend to accommodate this, or do we need to recognise that this site has limitations?

    So many choices, but most important, whatever keeps the site going with its great mix of contributors. I so appreciate that we have experts and non experts mixing their thoughts.

    So thank you to the dragons and all contributors. And does this whole discussion signal a good thing? That there are so many people interested we get more opinions! 😁

    • I have tried the VCBar, but threading is dismal (mostly because the provider’s software doesn’t handle threads well). In fact the way things happen here works surprisingly well, not least because old subthreads simply fade away due to nobody replying, this one is a rarity as lurkers have their say.
      Then periodically all threads are severed with a new article. The old ones get left unreplied to.
      So actually IMHO (and I remember threads on usenet that ran for months with tens of thousands of replies most far from the actual topic or each other) the format here is actually an excellent compromise between heavy (and time-consuming) moderation and total laissez-fair.

    • In days of volcanic excitement, as those when Bardarbunga did its thing, there were that many interesting contributions, it was very hard to keep up. A better structured site (other than a blog) had been helpful to choose what to read – what to skip.

      VC has many written gems, it takes hard work to dig out a particular article, which you want to read once more.

      I always have been in favour of a forumlike site for sake of clarity and a searcheable back up.
      I pity much it is just undoable to reread interesting things.
      As I have been trying to establish a simple phpbb forum recently, I know it takes a lot of time & energy to maintain things.

      I guess I will have to take the scroll disadvantage in the blog as the way it will be.
      I will be stuck on VC anyway! 😄

  21. my thoughts about the blog…

    I became aware of VC during the eruption of Eyjafallajokull – that happened a year after my second visit to Iceland.

    Having had a fascination with volcanoes since I was a child, VC is since then my go-to place for up-to-date information on current and past eruptions. (And speculation about upcoming eruptions too of course).

    Iceland has a special place in my heart, but I am very curious about other volcanoes too, and have visited a few of them in the past (though Stromboli and Fagradalsfjall were the only ones erupting during my visit).

    I cannot explain why Iceland gets so much attention, but I am fine with it. But I was following also very eagerly what happened at Kilauea a few years ago, what is going on at Taal right now, and additonally try to keep up with current eruptions by listening to the volcano watch podcast which gives a good oversight of the many volcanoes that are erupting around the world. (VC is mentioned frequently on the volcano watch podcast)

    BTW: the posts about the demise of the Viking population of Greenland was very educating too!

    • My comment about the first volcano a little down was an answer for you and Eyafjallajöküll. El Teide wanted his own place it seems 😉

    • Ah – Gutn Tog has a drone! What an excellent video. And it is astounding to think how rapidly lava fills that deep crater before sloshing away. It would be good to see the process actually start.
      Thanks for spotting this!

  22. That’s so typical for uns human beings with a truthful heart with loyalty. The first we see we love the most. My first volcano was Teide, Island of Tenerife. I’m not going up there any more as there are too many tourists.
    I love him from far. I had friends on the Island of La Palma further west who had a house near Tirajafe, west coast, from which we saw the most gorgeous sunsets. During the week they worked in Santa Cruz, east coast, so I had ample occasions admiring Teide sitting in the East like a God on the waves of the Atlantic Ocean. I thought his name was related to Deus and was happy.
    One day I found out that the First People there, the Guanche, named him. The name is derived from Echeyde, the place where an evil demon lived.
    For me El Teide from far is still a God taking a bath in the Atlantic Ocean watching over those seven happy islands.
    And I liked Hector’s piece about Lanzarote.
    Vista:

    • Doesn’t work out with wikimedia commons. It’s better in reality anyway.

    • Must have been incredible, the first person to observe Teide. Just a massive mountain rising out of the deep ocean, Hawaii is like this too but Teide actually looks like how a volcano is expected to look, a cone, with black lava flows down the side.

      It has always puzzled me though why Teide and all the other Atlantic volcanic islands are stratovolcanoes, where Pacific volcanoes are usually shields. Teide is made of evolved magma mostly so makes some sense, but Pico is a basaltic volcano and has fluid lava, its like Nyiragongo but in the ocean and not active.

      • I mean whoever was the first to see Teide, not meaning that you were that person 🙂

        • I know. What about Japan? More stratos or shields? Fuji much be a strato, right? Imagine the first one approaching from the east who saw Fuji.

          • Japan was inhabited since the Pleistocene so Fuji probably looked different back then, its modern appearence is Holocene it was very active around 9000 years ago I read somewhere. It also is still a stratovolcano too, but definitely a very big one at over 1000 km3 volume, actually might be the biggest active volcano not in an ocean basin.

      • I was more thinking of the likes of Darwin or A v Humboldt. They weren’t there. Nippon was quite isolated for a long time. The inhabitants wouldn’t have liked volcanoes too much I guess. Same with the Guanche and their demon.

        • RE: “Must have been incredible, the first person to observe Teide…..”

          On the plus side is this body’s ability to balance their sense of wonder with reality. To borrow from a Titanic survivor viewing from her lifeboat:” “There’s your beautiful nightdress, gone!!”
          %3Fauto%3Dwebp%26s%3Dc7cc51853609b88fc46b3bdb9950dc4a8b49d231&imgrefurl=https%3A%2F%2Fwww.reddit.com%2Fr%2Fpics%2Fcomments%2F2ddnhs%2Fmt_saint_helens_before_and_after_the_1980_eruption%2F&tbnid=UT8cFrNyNzvIYM&vet=10CAMQxiAoAGoXChMIoPO-noeG8gIVAAAAAB0AAAAAEAc..i&docid=LlQ8xd3t85o95M&w=630&h=472&itg=1&q=st.%20helens%20before%20and%20after&ved=0CAMQxiAoAGoXChMIoPO-noeG8gIVAAAAAB0AAAAAEAc

    • I love Tenerife and have been up Teide. Staying in the south west, on the dry coast side of the Island the rugged volcano is an impressive sight.

      The Los Gigantes cliffs are also astounding. Seeing the magma channels cutting up through the cliff faces is educational as is realising just how many millions of years have passed since that happened.

      • RE:”I love Tenerife and have been up Teide”

        I’ll give that a second. The National Park at Lanzarote also gives one food for thought while watching the current events unfolding.

  23. The lava dome on Great Sitkin is continuing to grow. Don’t go to have a look.. a minor eruption seem a possible outcome. But not certain, of course

  24. Wednesday
    28.07.2021 12:36:14 63.664 -19.080 0.1 km 3.1 99.0 8.8 km ENE of Goðabunga

  25. The best-documented volcano worldwide seems intent to be shaking off (well, toasting) some of that observation equipment. If the scientists still want to use their stations on the visir hill, they’d better pick them up very soon 🙂
    As in, potentially the next few hours…
    Wasn’t there a camera there as well?

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