Islands in the stream

Funka Asane newhalf fishing spot.

In the last few weeks, I have been unusually busy with things decidedly non-volcanic as the world turned quite a bit darker. Regardless I noticed that there were quite a few things going on in the volcanic part of the news, but that did not for natural reasons end up as big news items.

One thing I noticed is that the YouTube Hysterati have shifted their doom-saying from Yellowstone to Campi Phlegrei. I have wondered for a decade when the fashion trends of the hysteratis would change, seems like a war was needed for this to happen. I will come back to this in my next article, stomping hysteratis takes a few words after all.

Instead let us stick to the volcanism of the islands that ended up in my browser stream. After all, I for one love me a good volcanic island. I will below take a bit of a closer look at four of those happy volcanic islands, two of them have been covered a lot previously, but since they are doing new things, here we go.


São Jorge

Vulcão da Urzelina in São Jorge. Photograph by José Luís Ávila Silveira, taken from Wikimedia Commons.

The Azores is quite reminiscent of a slightly less tectonically active part slightly offset from the Mid Atlantic Rift and on top of a less powerful mantleplume. Basically, it is Iceland Light. Still tasty, but less frequently belching forth.

São Jorge reminds quite a bit of the Reykjanes Peninsula in that its elongated shape is caused by a regional faultline running down the length of the island. It is obviously slower at rifting than Reykjanes by quite a margin, but it is still there creating tension that needs to be relieved in a generally squirty manner.

It is also offset from the centre of the mantleplume in a similar manner, with the centre being believed to be over at São Miguel.

Regardless, for most of our readers this will set an understandable back drop to what is going on over there.

During March São Jorge has suffered a tectonic crisis that started at roughly the midpoint of the island and progressed to slowly move towards the WNW. This was caused by pent up strain, and as that was released by dilation a void was caused that sucked in magma from depth through old open deep feeder tubes.

Currently the authorities have the island at a risk level of 4, that equates that the island is in a pre-eruptive state.

The last on land eruption was the 1808 Vulcão da Urzelina eruption on the Manadas Ridge. It is claimed that the eruption started with thick greenish clouds of chloric and sulphuric acid gases together with carboxylic acid flows killed plants, I find this a bit dubious to be honest.

Yes, I believe the sulphuric part, and I could at a stretch imagine how there could be chloric gases, but carboxylic acid flows? That would be a vinegar volcano for you, so a hard no on that.

So, what may come? Currently it looks like it could erupt at around the point of where the seismic crisis started down to any point along the seismic line. We will not know the specific point until the seismicity concentrates and start to move upwards.

Will there be an eruption? Judging from the low lever seismic release, at least relatively speaking, I would say that it is 50/50 for now. It all depends on if the activity can continue like this for another month, otherwise I think this will end up being just another dyke emplacement of lava.


Taal Caldera

Taal back when it was a complete gas bladder.
Photograph gently stolen from CNN for non-nefarious purposes.

First of all, if you are an itinerant journalist, here is some good news for you. Taal is not one of the world’s smallest volcanoes as most news articles state, it is instead one of the largest active volcanoes on the planet.

Problem is that the island in the lake is seen as the volcano, but that is just a small vent in the much larger actual volcano that covers all of the lake, and all of the land inside of the 20 by 35-kilometre caldera. Small my…

We often cover Taal as it is progressing towards its next eruption. So far it has only done small phreatic detonations, it is still building up towards the big show.

So, I will only mention the news. The level of released SO2 has dramatically dropped from peaks well above 20 000 metric tons per day, to well below 1 000 metric tons. This seems to indicate a blockage in the geothermal system of the volcano, and those tend to be blown out sooner or later.

So, do not be to surprised if you wake up to find that there have been one or more large phreatic detonations hurling ash and gas up towards the 10km mark. Right now, I do not think this is the famous quiet before the proverbial storm.



Reshaped Nishinoshima Crater. Photograph from the Japanese Coast Guard.

It is time to discover a bit more about the land of volcanic plenty that is Japan, but first let us take a look at my absolute favourite newly born volcanic island, Nishinoshima.

While we have been busy gawking at other new shiny volcanic eruption this little island that could have been busy doing some landscaping of its own. The change to the volcanic cone on the island is dramatic.

The cone has collapsed on one side, and it looks like it also have collapsed inwards down into the ground in a minute caldera subsidence event. Normally this is a sign of magma reservoir drainage, or due to cold shrinkage of a hot volcano causing voids for parts of the top to fall into.

The Nishinoshima Onzen gently steaming, photograph by the Japanese Coast Guard.

Judging from the fumarolic activity on the picture above I would instead say that it may be flank movement of the entire edifice that instead have created the edifice to fall in on itself since this also creates voids.

It is here good to remember that the island is very steep below surface, and that it as such is prone to failure.

Another sign that the island is still active is the large increase in fumarolic activity on the later photograph taken by the Japanese Coast Guard.

I am certain that what we are seeing are just a brief repose before the next volcanic phase, and even as reposes go Nishinoshima is a real cutey of a volcano.

Let us stay within the confines of Japan and move to an actively erupting volcano, and this one has the name worthy of a Japanese newhalf gangstah-rapper.


Funka Asane

The eruption of Funka Asane. Photograph by the NASA Earth Observatory.

Situated in Ogasawara Island chain north of Ioto (Iwo Jima), 5 kilometres north of Kita-Ioto and 130 kilometres south of the Fukutoku-Oka-no-Ba that had a large eruption in 2021, Funka Asane is a more unknown entity.

It should not in any way be less well known. After all it is one of the most frequently erupting volcanoes in all of Japan.

It is not known if this is a new vent of the long dormant Kita-Ioto volcano, or if it is a separate volcano. Regardless, Funka Asane has an interesting history all of its own with the first recorded eruption in 1780.

After that it erupted for nine years between 1880 and 1889, with the next eruption occurring between 1930 to 1945. After that there have been 16 instances where either fishing vessels or the Japanese Coast Guard have reported steam, turbulent water, and discoloured water indicating potential smaller eruption emanating from Funka Asane.

Naval Chart detail, image by the Japanese Coast Guard.

At 06.00 Sunday the 27th of March a satellite recorded the start of a new powerful eruption at Funka Asane with ash and steam rising to 7km height. It was reported by fisherman that the eruption consisted of Surtseyan rooster-tails reaching between 300-700 meters in height.

This is a common fishing spot for Japanese fisherman, so not much happening here without getting noticed. I guess those fishermen got quite a surprise since there seems to have been no warning on the surface prior to the eruption, and the volcano is not instrumented.

Prior to the eruption Funka Asane was a shoal that barely touched the surface at low tide, so an island formation is definitely not out of the question. It also seems quite likely that this eruption will last for years at a sedate pace.

I love the smell of a fresh volcanic island in the morning.


86 thoughts on “Islands in the stream

  1. Thank you Carl

    Sao Jorge seems To be unsoure If it wants to erupt. If it erupts it will look like La Palma I guess

    • Still working on my Nyiragongo article
      Writing on it When I haves time

    • Probably smaller and a bit more explosive than La Palma, low viscosity magma but high water content. Pyroclastic flows reported was probably a flank collapse of a cinder cone, same as happens on Etna and Fuego, no plinian eruption required.

      I think it will definitely erupt, just not quickly. Comparison to Reykjanes is appropriate I think, takes time for these systems to get going, it isnt near instant like it is in Hawaii or Vatnajokull.

        • Not sure it took that long, the tectonics dont allow it unless extension happens. But has taken at least 15-20 years still. Now probably all the systems will fire in short succession.

    • There is a huge vaierty of magma in Azores its all on the alkaline spectrum ( sourced from small ammounts of melting ) but with diffirent compositions and Sio2 content.

      It ranges from hot fluid alkaline basalt with viscosities almost as low as Hawaii, To cooler alkaline basalts with higher heimeay like viscosities

      And under the large central volcanoes in Azores you finds evolved trachytes basicaly alkaline andesite/dacite. They form in shallow magma stoorage keept alive by a slow magma supply

      In Sao Jorge there is no shallow magma stoorage althrough there is a deep deep stoorage there

      • Most eruptions there are probably a lot like the recent eruption on La Palma, gas rich but fluid lava, so lava flows but also substantial cone building. Pico probably built up this way, probably through many such episodes of activity, the last eruptions of that episode being a lava lake from the open conduit. La Palma cone is 400 meters tall on the downhill side, a few eruptions like that in the same place. The rest of the island is a fissure swarm very similar to Sao Jorge, maybe it is a slightly more advanced system, with a basaltic central volcano newly forming.

        Even if Sao Jorge doesnt erupt now it is clearly active and will probably erupt in the near future. Given the known extent of the dike too it will be on land, first time in a long time for the islands.

      • If Sâo Jorge has any magma left over from the 1808 eruption, it will be andesitic.

        • Maybe, but the heat flux might not be high enough to keep magma in an intrusion solid for long enough to turn to andesite. Kilauea fissure 17 in 2018 was from an actual small magma chamber, that area gets new magma every few decades. Same thing is probably true of the evolved central volcanoes that exist on Sao Miguel and Terceira, the magma supply is low but the heat flux is substantial, otherwise the magma chamber would solidify.

          At risk of stepping into Carls territory 🙂 the geological situation at Sao Jorge looks also very similar to Vatnafjoll, the fissure swarm next to Hekla. No exact central volcano or evolved magma at either, and alkaline composition indicative of fairly deep melt origin. Vatnafjoll does still have an actual magma chamber though, probably same depth as Hekla,10-20 km, maybe they are the same structure but the magma doesnt mix, or not. So probably if it does actually decide to erupt it will be a very fast and very seismic event, like Fagradalsfjall swarm but in a few days not a month, then big lava flood, basically Holuhraun but erupted in 2 days not 6 months 🙃. After that slows down the eruption might well be more or less identical at both systems, strombolian cone fed at mantle supply rate, quite photogenic and possibly long lived. Will definitely not be a lava flood to start things off at Sao Jorge though 🙂

          • I was going by an account I’d read of the 1808 eruption. Lost the link now.

            Would a basaltic intrusion at depth, wake up any andesitic / other old magma?

          • It would if that existed, but it seems there is nothing of that sort here. Not really sure why, might be the narrow shape of the island, but in any case there is no magma chamber within the island itself, only at the deeper levels probably at the base of the crust. Probably any dikes at depths suitable to evolve will just go solid before another eruption.

            Can look at the other Azores islands that do have evolved magma, those also still have fissure swarms and basaltic eruptions, Sao Jorge is maybe the youngest island and has just not reached this stage at all yet, still at stage 1. Pico might be getting to stage 2, with a proper defined center but still only basalt. Sete Citades and Agua de Fogo on Sao Miguel, and Santa Barbara on Terceira are type 3, silicic calderas with active basaltic flank vents. Furnas on Sao Miguel is a type 4, only silicic caldera, it might be very old and dying. All only based on visible characteristics though so probably wrong.

          • Narrow dykes tend to solidify fairly rapidly unless they are Laki sized.
            There is no central magma reservoir here.

          • Was not aware andesite could form that deep in an oceanic setting. Interesting. Would still be more likely for a basalt eruption but it might start off with some more fireworks then.

            After that now I am wondering if this just happens anywhere that is cool enough for basalt to crystalize. If it is over 1200 C it will not evolve. Sao Jorge might be quite cold at depth then.

  2. Nishinoshima became fully basaltic during the last part of its previous eruption, hence the tall fountains and such, gas rich magma from the source rather than the more degassed andesite from the magma chamber. So whatever magma chamber it used originally to create the island is apparently used up now. Next eruptions then might be shorter and more violent than before, sort of like Etna when it has a paroxysm. Would likely involve a massive fountain and fast lava flows covering the island at intervals of one to several times a year.

  3. Volcanism in the 2020’s seems to go for islands. In addition to the ones you mention, there are Hunga Tonga, La Palma, Reykjanes, Kilauea. Even Etna and Merapi are on islands. Continental volcanoes are decidedly being outplayed here.

    • I guess Oceanic Settings have thinner litospheres and its easier for magma to reach the surface

    • I stayed away from those since we have covered them extensively quite recently.
      I wanted those that had popped up on my radar recently.

      And Funka Asane was definitely something that I enjoyed, had completely missed that one before.

  4. Ruapehu drum displaying interesting weirdness:

    Looks a bit like an partly blocked stovetop espresso on an element with a dodgy thermostat.

    • Good analogy for Ruapehu.
      We will see if it blows out a chunk or two.
      Seems like there has been a blockage running for quite a while now and that it takes a bit of time to break through.

      I wonder what you use to get good speed on your skiis if you are running on ash? 🙂

      • Hey Carl, what do you think of Taal as of late? Phivolcs says that the hydrothermal chamber has been depressurized and since the gas emissions have gone down there is no more shallow magma but I have my reservations, however it does looks pretty stable over there.

        • I think that there is a blockage in the hydrothermal system and that there’s been no change in the magma supply at all.
          As soon as the blockage has gone we will see return to phreatic detonations and high gas content.

          Magma rarely, if ever, just “go away”.

          • That’s what I was thinking, and we’ll find it out soon enough, The recent interferograms show inflation around Taal but Phivolcs doesn’t talk of inflation. I don’t understand why they won’t just give detailed descriptions of the deformation surrounding Taal, I am skeptical of third-party resources but that’s really all I’ve got.

  5. Will not be enormous
    How Big Will Nishimoshima Island get?
    Its fluid Aa andesite lava flows looks very similar to Tarso Toussidé s Aa lava flow tounges. But perhaps coud grow into a grand stratovolcano like Lopevi

    • It’s already a giant arsed strato to get up from the ocean floor…
      About half of the old caldera is filled up now, so it will only become twice the size before it will have to start expanding the entire edifice, and that will slow growth prodigiously.
      To be honest I think it will have a flank collapse before that happens, it is incredibly steep on one side. If it had been on land it would have failed a long time ago, but the pressure from the water is propping it up.

      Nishinoshimas edifice is 4200 metres tall on the steep side towards the Ogasawara Through, and 3200 metres in the other direction. Quite something.

      • The caldera formed during a flank collapse by the way.
        Same goes for the neighbouring Doyo and Kaikata Seamounts. The also suffered from flank existence failures.
        All 3 of them have galumphed out into that through, with Nishinoshima having had the largest failure.

  6. From the way the lead picture of Funke Asane shows that ‘planed sea-mount’ summit is sub-aerial again, may we assume ample inflation ??

    • Do not forget those pesky tides…

      Also, that is just ash, and I do not know how old that picture is.
      It is quite likely that what is seen on that picture was removed by the ocean prior to the start of the eruption.
      It usually takes something on the order of Surtsey or Nishinoshima before an Island stays put for a longer duration of time.

  7. Nishimoshima haves a beautyful viscosity
    Its quite viscous.. ( thicker than Etnas lava ) yet quite mobile. Its between Etna and Nea Kameni in Viscosity or also similar to Heklas hot Andesite in viscosity. It looks alot like Nea Kameni just somewhat more mobile in viscosity

    It coud be a hot andesite or a basaltic andesite or a very very cold crystal rich subduction back arc basalt. I think its a Basaltic – Andesite and they typicaly looks like this When They erupt.

    Nishimoshima produces fantastic Aa flows, strombolian explosions and can produce enormous lava fountains with this viscosity combined with high gas content. That whole Island is full of Aa lobes and clinkery channels 🙂
    The lava is quite dull red in daylight and cools quickly once the hot surface is exposed.

    As Jesper himself found out, big pictures is not that good, it ruins peoples bandwidth.
    The images was gorgeous, but took forever to load, so we had to remove them.
    /Admin (hoping the Jesper will reload them in smaller form)

    • Ops loaded too much Photos
      Better to crop them To lower resolution

      • Yes, please do. They are in the dungeon at the moment but are really too large to release!

    • Island building lava was andesite, 59% SiO2, and about 1000 C. The lava after June 2020 up to the end was basalt at 1100+ C, would have been hot and fluid but it was gas rich and then phreatomagmatic so no lava flows. A future eruption though will probably be basaltic and strombolian.

      • A very hot andesite then
        Fluid enough to form Aa channels and Strombolian eruptions like Heklas

        Most other andesites erupts at around 800 to 900 and are very viscous because of that

        • Was about the same temperature as the fissure 17 andesite, maybe a bit less but similar. And similar to Hekla yes.

    • Great catch, Albert! I was going to post the link myself. And, I’m not ashamed to say that Professor Cronin is a better man than I am!

  8. I should probably tell everyone that I have hidden 3 different cultural references in the text.
    Clarke Eligue spotted the first one before I even had intended for divulging that I hid a little riddle in the text.
    He found the Bee Gees / Dolly Parton reference.

    The 3 references gives a riddle of sorts.
    Have at it.

    • Noted the Dolly/Kenny Rodgers hit song at the beginning, and a reference to coffee in the last sentence. Other than that, several references to things that happen below the belt. Hasn’t coalesced into a riddle though.

  9. Let’s return to my favourite volcanic Ísland for a while. Some unusual quake activity a bit out in the dead zone, right next to the Eldgjá canyon:

    12.04.2022 04:07:50 63.952 -18.681 0.5 km 1.9 99.0 19.0 km ESE of Landmannalaugar
    11.04.2022 15:02:15 63.952 -18.671 0.1 km 1.0 99.0 19.5 km ESE of Landmannalaugar
    11.04.2022 14:28:05 63.952 -18.677 0.4 km 2.8 99.0 19.2 km ESE of Landmannalaugar

    • That small swarm in the northwest region (NNW of Hveravellir) is rather an odd location.

      Also, looks like more activity on the peninsula I see, a 4.2 and a swarm south west of Reykjanes.

  10. The last sentence – definitely an Apocalypse now reference.

    Also, a vinegar volcano sounds plain odd. Carboxylic acid is more reactive so the acid rain would be in higher concentration than the usual sulfur/nitrogen mix. You’d be able to see the after effects in the soil in studies.
    It was more likely Chlorine or Sulfur based, potentially Phosgene was produced.

    • Nope on the Apocalypse now 😉
      It was at least not an intentional reference.

      A volcano erupting carboxylic acid is a nogo. But, somehow it is stated in several papers that it erupted “streams” of just that in 1808. I think it is a case of mistranslation that just continued to be spread around.

        • Possibly, but that’s not all that toxic and it’s a fairly weak acid.

          Hydrochloric acid (and chloride gas) could be produced when lava enters the sea.

          As above Phosgene is possible but fairly unlikely, Phosphine is very possible though.

  11. Reykjanes really going now. Doesnt look like this will erupt but I think this location is a good bet, been swarming quite a bit this past few months.

    • In Iceland at the moment It’s almost like you can see the whole rift gently popping from Reykjanes to the north of the island.

      It’s done the star burst of earthquakes a couple of times in the last year or so, that I’ve seen

      Amazing how quickly the patterns have shifted slightly over the last 18 months and there are earthquakes appearing in all kinds of place that are not that common.

  12. Was a small swarm of deeper quakes at Kilauea this week, maybe I will have a firework show 🙂
    With my luck though it will probably go into a lull right before I get there and only pick up again on my last day 🙁

    Lava lake is about 340m deep, containing about 110 million m3 of lava, 0.11 km3, now is volumetrically a VEI 4 🙂
    It will reach the downdropped block when it reaches 900m elevation, currently sitting at about 860m. So that quite small looking cliff at the back of the lake on the F1 cam is just over 40 meters tall, volcanoes are big.

    • Gives an Idea just how gigantic even a 0,1km3 eruption really is .. a number that I tought of a small volume before
      Fagradalshraun was pretty insane as well

      And not to mention leilani 1,5km3 that became 0,1 km3 bigger than Holuhraun 🙂 F8 was a real Lava Flood

      But an eruptions volume says nothing about its intensity

      • Yes, not exactly the most intense eruption, 0.11 km3 in about 1.5 years, which is a little lower than the average for Pu’u O’o. It did stop for 5 months though, which will offset a bit. Seems today it is significantly higher than Pu’u O’o average was though.

        Fagradalshraun was about twice the effusion rate average.

        Ahu’aila’au being actually a bit bigger than Holuhraun was a surprise to me actually, I expected it to be a bit less though was erupted faster. Holuhraun had a larger gravity differential and kept open a longer section of fissure but I guess a 50 km long dike is a less effective magma path than whatever pathway exists to cover the same distance at Kilauea. 2018 erupted from a dike but that dike began in the LERZ, from a satellite magma chamber a bit west of highway 130. But then Holuhraun was also hotter, so not sure cooling along the dike had much to do with it.

    • Kilauea is so insanely huge for soure its massive goes 64 km South of Halemaumau into the 5700 m deep ocean .. and it extends 200 km north along the puna ridge 🙂 as a long massive edifice

      Most land stratovolcanoes barely scrape 10 km wide and 3 km high

    • And Mauna Loa thats 20 km high must have the most insane gravity potential in the inner solar system among active volcanoes

      The Big Mauna Loa caldera drainouts like 1720 s probaly even puts Laki to shame at least in eruption speeds 🙂
      Must have been like a hoover dam burst of lava

      • 9 km high, 20 km thick 🙂

        1720s eruption at Hapaimanu volcano above Ocean View had a 2.5 km difference. Not sure if this actually matters too much though, quite a few historical eruptions were lower and not as intense, and 1950 was not really low at all but had the highest rates observed of any effusive eruption in recorded history when it started, going on 0.5 km3 a day (for 3 hours 🙂 ).

  13. Taal has generated a 2,800 m tall plume with gas and volcanic quakes now on a slight uptrend, is the volcano about to clear it’s throat?

  14. Looks like there was a dike intruded on Reykjanes just recently. Swarm went offshore as it progressed. Was not very big but happened fast, and in a different place to the other ones which were under Fagradalsfjall. Has only been 8 months since that eruption ended and there have been 2 intrusions in that part of the peninsula.

      • Is high frequency meaning high rate of events to indicate rapid intrusion? Or does it mean the same as pitch, and therefor not magma at all?

        • Think of the frequency as related to the size of the fracture or event. Higher frequency would be smaller quick fractures, lower ones would be larger fractures if that is what is generating it.

          • So this would be small quick fractures, which sounds like a magma signal. I presume larger fractures would be from tectonic quakes or much larger magma intrusions that break large sections of ground, like at Kilauea in 2018.

            The swarm stopped but theres definitely something going on here. Would not be surprised if this place goes off before Grimsvotn even, which seems to be sleeping on the job.

    • Didnt know about this before just now 🙂

      Given how many volcanoes, especially basaltic, are submarine it is likely events like this are relatively frequent. Reykjanes is an example where this happens on land, Afar possibly is too, but there is orders of magnitude more underwater. The most active MOR segments are underwater too, we will certainly see many more events like this.

    • Volcanoes should be classified as potentially eruptable, erupting or extinct. This one erupted sometime between the pleistocene and the last few thousand years…


    Found this documentary just now. It is in french and video quality is not great, but still interesting. 11:25 onwards there is a great view of the opening sequence of the 1984 eruption of Krafla.

    If anyone wants a visual of what will happen to Grindavik in the near future, unfortunately…

  16. Pahala has some indigestion

    2022-04-15 07:58:33
    Magnitude :4.6M
    Depth : 19.6mi
    2022-04-15 07:58:24
    Magnitude :4.3M
    Depth : 21.3mi

  17. “This little island that could” is a clear reference to “The little engine that could”. I tried to hint about that on the facebook page by giving a reference to the reference, “I think I can”, puffed the little island, but I’m not sure it was noticed.

  18. Just watching the documentary on the final day of the dinosaurs and the fossils of Hells Creek. It started out as ‘The final day of dinosaurs with David Attenborough’. I hadn’t realized he was that old.

  19. I have noticed the attention given to Campi Flegrei as well.

    Weird you name it.

    I also read more about the Lisbon quake article here. Apparently there were earthquakes in the 12th century, 1321, 1533, 1722 (evidence lost in the fire following the major Lisbon quake) and likely an aftershock in 1761 which also caused a tsunami that was observed in the Caribbean, Antigua in particular.

    Not all of these will have been megaquakes of course. the 1755 was the heaviest and the 1761 likely a very severe aftershock.

    But whatever caused it is unusually calm, although portugal hasn’t been a center of civilization, even during the Roman Empire (just a province?). In fact, everything in Europe seems pretty calm right now in terms of earthquakes. Feel like if you read more about medieval events, there have been more earthquakers than one would think based on the activity in my life so far.

  20. Thanks for the great article. I was definitely bitten by the dinosaur bug as a kid. Even wanted to become a palaeontologist well into my teens.

    What’s the title of the article that was locked behind a paywall? I can see if I can access it for free.

  21. Busy as well and seeing this late. Very nice summary, thank you, Carl.

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