Nishinoshima – The Seminal Eruption

Firefountains in the night.

Nishinoshima is in many ways the perfect volcano, it is constantly doing firsts, and spectacular and unusual things. Normally volcanologists would gather nearby and play lip-banjo at its antics. But since it is far out into the ocean and is so inaccessible most miss this beauty of a beast.

In November and December of 2013, it gave us both the birth of a new little island, and an island merger as the old island and the new one merged together. After this eruption ended in November of 2015 scientists landed to start observing how life would return to the island. It was at that time believed that the volcano would rest for quite some time before erupting again.

The volcano proved them wrong as it returned to a state of eruption in April of 2017, an eruption that lasted into August of 2018. Since this eruption was smaller than the first eruption scientists once more returned to the island to observe life take hold.

Infrared showing the insane rate of lava pouring out.

After all, smaller secondary eruptions are not unheard of in the life of a volcano. Surely Nishinoshima would need a geologically sized nap after all this activity, especially since the eruptions comparatively had not been small by any measurement.

Problem is just that a third eruption started again on the 6th of December 2019, and this eruption was larger than any of the two previous eruptions. Not only was it larger, it also kept going at a steady state rate for months building more new land than what had previously existed in total.

This should have lifted a few eyebrows, volcanoes rarely if ever increase in eruptive size as closely spaced eruptions occur, and even more rare is eruptions that does not diminish over time.

Come June Nishinoshima decided to take things even further as it increased the eruptive rate with an order of magnitude.

 

Current state

The purple in the image is the ocean boiling away due to the heat of lava entering the water.

What started in June moved Nishinoshima out of the realm of ordinary eruptions into the major league. Nishinoshima was never a small volcano to begin with, but nobody expected it to take up the competition with big hitters like Grimsvötn in Iceland, Kelud in Indonesia and Kilauea in Hawaii.

Currently the ash-plume is ranging between 3km and 8.3km, and the happy little fire-fountains are 500 metres tall.

There are two ways to count volcanic prowess, the first and most widely used is the Volcanic Explosivity Index (VEI) Scale. As the name implies it measures how explosive an eruption is over time.

The VEI-scale is useless for effusive eruptions, so there we use the very simple solution of measuring the total output of lava over time. This is the realm of Icelandic volcanoes, with a few interludes from Hawaii.

If we stick to this millennium we find that the two largest eruptions are Kelud (0.8km3 tephra) and Grimsvötn (0.9km3 tephra) making them into borderline VEI-5s, both are though counted as very large VEI-4s since both Icelandic and Indonesian volcanologists are made out of stern stuff.

Finding Nishinoshima trailing those two at a third spot is quite a surprise. Grimsvötn and Kelud did though reach those levels a lot faster than Nishinoshima, but it is still not a small feat.

If we instead look at the amount of effused lava counted in cubic kilometres we will find that Nishinoshima is doing quite well against other big hitters during the current millennium.

The rate of flow has carved a broad crack that the lava is following.

At third spot we find Kilauea with 1 to 1.2 cubic kilometres of magma erupted during the last eruption.

Calculating effused lava at Nishinoshima is a bit harder since most of it end up in the ocean. Thankfully, there are naval charts so we can calculate how much must be infilled at a bare minimum to build up new land.

And as landmass increases it takes more and more lava to come up to surface level. An absolute minimum is 1.2 cubic kilometres with a highest solution at 1.8 cubic kilometres.

Currently every new square metre of land needs to overcome a depth of 200 metres or more. Add to that sub-aerial over-layering and the numbers tally up quickly.

If the eruption continues for a bit longer it will transcend even Holuhraun that is currently in the lead with its 1.8-1.9 cubic kilometre eruption.

 

The problem

Ominiously glowing in the volcanic dusk.

Nishinoshima is classified as a back-arc subduction volcano sitting beside a spread-centre Graben known as the Ogasawara Through.

Volcanoes of this type are known for there intermittent explosive volcanism, most often the eruptions are small. But if the dormancy period is long, they can go big with VEIs of 4 or even an occasional VEI-5. This is though very rare.

What they do not do, is erupt like a combination out of hell of a main-arc subduction volcano combined with a major mantleplume volcano.

And not even those do progressively larger eruptions in a short timeframe, or eruptions that ramp up over a long time. They tend to go big, dwindle and go for a prolonged snooze.

So, as June came around, I started to really think about what the heck was going on. In the end I came up with a solution, but it is so out there that I will probably be laughed at.

But, if it quacks like a duck and walks like a duck, it is probably a duck. I am up for being bloodied by Occam’s Razor.

 

The solution

If you would stand on the top of Mount Nishinoshima looking due East out over the ocean… Well, yes you would be epically and immediately dead, but let us disregard that piddly problem. What you would be looking out over is the 3000-meter-deep Ogasawara Through, a spread-centre Graben, that Nishinoshima is precariously perched on the edge of.

Further out you would see a couple of small fly-speck islands, those are main-arc subduction volcanic islands. Beyond them is where the subduction is taking place and you have a subduction abyss reaching down almost 6000 meters.

Ever so slightly north of east of Nishinoshima is where the deepest point is, and the spot where the subducting oceanic crust has the steepest angle.

This is a bit of a problem in and of itself as subduction volcanism goes, steep angles of subduction is generally a bad thing for back arc volcanism since the melt would go pretty much straight up, short-pitching for back-arc volcanism to form.

In other words, this means that there should really not be a duck around since it would starve to death in a volcanic dessert.

Let us instead look at the Graben, those are after all known to on occasion to cause decompression melt as they spread. In the case of the Ogasawara Through it is spreading slowly, so it is a bit of a barren source, and it would produce minor volcanism at best.

If we instead look ESE from Nishinoshima we find that the angle of subduction of a bit more shallow and that an oceanic ridge is being pushed down into the mantle, this part could at least be a part of the solution where the eruptive material originated from.

What it does not explain is this weird increase in time of the eruptive strength and the ever less viscous material that is effused.

Regional mantle upwellings above 100km depth. Image produced by Andrej Flis.

In the end I was so out of options to explain the eruption that I started to grasp for straws, pondering how mantle upwellings form and how they transition into becoming full-blown mantleplumes.

So, let us toy with the idea that the more explosive material is coming from that oceanic ridge subducting, it would at least explain the explosive part.

Let us also ponder the idea that the Graben is producing some nice decompression melt. And finally let us assume that the steep angle subduction is working as a scoop tugging at the mantle at depth causing a mantle upwelling, and that this is creating a shallow proto-plume burrowing downwards.

How does a mantleplume look like when it is born?

We do not know what it would look like, we can just assume that it would be messy. And mess we have aplenty. One thing is though for sure, it would leave measurable signs.

This is about when I asked Andrej Flis to plot the available data to see what we would find, and if there would be even a small shard of evidence pointing towards my idea being correct.

 

The birth of a plume

100km seismic plot indicating plume-root formation at 100km depth. Image by Andrej Flis.

As a plume is born you get an increase in sub-crustal pressure causing localized fracturing, and as the fracture becomes critical an eruption will start, but the fracture will need to develop over time, and for a long period the build up of mantle pressure will be larger than the release through eruptions.

This part of the process would take tens, if not hundreds, of thousands of years. Time enough for a chain of volcanoes to build up, behaving quite as more normal volcanoes do.

Below the crust both pressure and melt would start to build up as the mantle started to convect deeper and deeper, this would be visible as a low velocity zone below the crust. In the beginning it would be like a wave under the crust.

But as the mantle convection wave takes the step towards plumeliness there would be a distinct root forming at 100 kilometres depth or more. If you find that you have a case that something is well and truly going on down in the mantle.

And once upon a while the torch is well and truly changed into a blow-torch and it starts to cut up the crust above and a LIP form out in the ocean, creating new continents.

Next comes eruptions larger than they should ever be in normal circumstances and that are more frequent and long-lasting than anyone would expect.

Carl Rehnberg

119 thoughts on “Nishinoshima – The Seminal Eruption

  1. Great Articel as always, Carl. Thank you for it.
    I am quiet exited what will happen next at Nishinoshima and how long would this eruption last.

    Greetings from Germany

    • I get a nasty feeling it’s going to do an Anak Krakatau in the not-so-distant future…

        • Unfortunately, tsunami waves can kill at very considerable distances

      • I would think that it is more likely that it will do a version of Mt St Helens, and that the over-steep side facing the Graben will galumph out into the ocean again.
        After all, it did that previously.

          • Against popular belief collapses like this do not cause large tsunamis going far.
            Earthquake tsunamis are, when they do happen, often quite larger and have more far reaching consequences. I would though not like to be on one of the islands on the other side of the Graben if that would happen.

            For reference, Tohoku Earthquake moved all of Japan 3 feet eastwards and upward flipping tongue of the fault displaced a couple of orders of magnitude more water than even a large landslide would do.

            I should probably write a post about it one day… But, that might be a decade away before I get the time. 🙂

  2. Whats the composition and temperature of this lava thats oozing out?
    Looks very blocky in closeup photos.
    Yet fluid shapes from the air: nature is indeed fractals. But its does not look very hot in daylight, hardly glowing.

    • It is not as hot as let us say Iceland or Kilauea.
      But the lack of visibility is more due to distance of the photography than temperature. And the lava forms broad lobes whose surfaces are covered with cooler material while the hot stuff runs under it.
      Yes, there is peaky looking spatter cone there, but the rest of the island is shaped like a shield volcano.
      Judging from the colour of the material of the lava it is basalt (black), but the ash is grey to brown indicating that it is andesite.
      It is definitely a bi-modal magma that is coming up.

  3. Here is a bathymetric map of the island from 1911, and a higher resolution one from 1992 when the island had been enlarged. The old island was part of the rim a small caldera, with maximum depth just over 100 meter, southeast of the island. This was a large submarine volcano which at some point underwent an explosion. The arrow points at where I think the current eruption is happening, again on the rim of this small caldera at a depth of perhaps 30 meters.

    It would be interesting to overplot the contours of the current island on top of this map. I think it has filled in the caldera.

    • Today it is basically covering all the way out to the 200 meter bathymetric line.
      The arrows basically point to where the initial eruption in 2013 started, That eruption after a while opened up new craters.
      If memory serves it was a grand total of 9 craters active, and in the end one of the centre craters remained open as the others closed down, and then it grew the current spatter cone.
      The vent today is pretty much at the sharp corner inside the ring of the island.

  4. I’m curious about the low-velocity zone in the middle of Honshu – I’m not familiar with Japanese volcanoes… Is there a relationship between the zone and mount Fuji? I see that the zone is somewhat offset from Fuji itself – is there stronger activity directly above it?

  5. Above I mentioned that Nishinoshima has previously suffered a flank collapse.
    It was a massive one to boot. You can easilly see the massive hummocky debris field that slid out into the Graben. This is what caused the caldera to form, probably explosively, as an entire section of the Graben wall failed around the bloated Nishinoshima of old.

    • It looks like a collapse. There is a larger one on the opposite side of the graben. But it must be very old because the underwater mountain looks very symmetric. I’ll upload the larger bathymetry map. It shows a line of cones to the south, connecting to another subsea mountain. It is a very active area.

      • Note the plateau feature at the top right corner, and the line of cones towards the bottom

        • Given the rate that Nishinoshima can expell lava, it might not be that incredibly old.
          But you are absolutely correct, there are loads of cones on the volcano, and it is flanked by two other sizeable volcanoes.

    • I have to wonder if Nishinoshima was to undergo a flank collapse at least as big as Anak Karakatau’s or even bigger, how much of a tsunami risk this could pose to southern and central Japan?

      • Not main land Japan. The collapse would most likely be eastward, where the trench is. And Osagawara is on the other side, not that far away. Anak Krakatau has shown us not to underestimate the collapse of a small volcano (Henrik’s Iwo Jima post was remarkably foresighted in many regards, although it missed the possibility of flank collapse which perhaps for Iwo Jima is currently unlikely, and overestimated the likely size of an eruption so that is good news)

  6. Thanks Carl for this one!
    It will be a beautyful new addition to earths Islands.

    This lava thats comming out is probaly all a ”very hot” Andesite, that flows kind of little like heklas lava when HK is effusive after major opening.

    The cone on the Island is a cinder cone, made mostly of loose materials tumbling down from the angry vents.
    Most of the materials are too viscous and cold to call spatter when they come down. This is mostly a cinder cone
    Not a spatter cone. But larger bombs do deform when they hit the ground.
    My brother thinks the lava is 1080 C

    Information very carefuly selected for you from me and my brother
    Cheers from Johan and Jesper

  7. Compliments to Carl for this article. I have been watching the news, when it comes out, about Nishinoshima. The fact that is erupting the way it is, is fascinating. I hope the island will become sturdy enough, that most of it will survive after the landslide into the deep.

    • That would take something in the order of Hawaii sized island.
      If it slides again, the island is toast again.

  8. Thanks Carl! Exciting story and hypothesis! Will be interesting to follow the development!

  9. Query for -well, Albert I guess. This morning there was a new VC post about Rainier in my inbox, but clicking just gave a ‘page not found’ Something in the pipeline?

    • Cough…
      There was an incident where both me and Albert succeeded with editing in an article at the same time and publishing at the same time without either of us knowing.

      Short story, in a few days Rainier will indeed be the topic of a post.

      • It will come, but it was about time there was a post about an actual eruption. By the way, how large was the Mayotte eruption? Should it be in the list?

        • Mayotte is hard to calculate properly, it will be interesting to see if there ever will be any calculations done.

        • For the Mayotte eruption, scientists from the REVOSIMA surveillance network estimate a minimum volume of 6.4 km^3, with approximately 170-180 m3/s between July 2018 and June 2019.

          And the eruption is still ongoing… The most recently documented activity, produced 0.8 km3 between 21 August 2019 and 11 May 2020.

          You can find all reports here : https://www.brgm.fr/content/volcan-seismes-mayotte-suivi-activite-sismo-volcanique-revosima.

          But they are in French…

          By they way, i’ve been following for a long time the posts from VolcanoCafe, and I take this opportunity to thank you all for these really enriching readings. 🙂

          Thank you. The comment was held back for approval. Future comments should appear without delay – admin

          • Thank you Marc!
            If true Mayotte would be something special, I am though waiting for more data before entirely trusting those figures.
            In the end someone would find a new sizeable mountain on a sonar if true and then we could do the numbers.

          • After a quick read it seems like they have calculated size from subsidence data from a limited set of GPSes. They have a somewhat good set of data, but the arc emplacement of the GPSes is to small to give reliable tilt data.
            The data comes with a margin of error that is so big that it is impossible to tell eruptive volumes.
            Sorry for being grumpy, but here they should go and measure directly prior to making claims that are unsubstantiated.

          • I think they are also using bathymetric surveys to contsrain volumes (see for instance page 19 and 20 here : https://www.brgm.fr/sites/default/files/revosima_bull_19.pdf#overlay-context=content/volcan-seismes-mayotte-suivi-activite-sismo-volcanique-revosima).

            The structure at the low right corner of the yellow rectangle in the new volcano. It has been found by compariing with a topographic survey done a few months before (or at least not long before) the eruption.

  10. To avoid confusion could Mt Rainier be deleted and we can return to it in the future and have this one as the main thread?

    • That was already done. Apparently it is not that easy to keep you out, if you can still see deleted posts!

    • Aww, don’t delete Rainier, it’s too pretty to get rid of! As long as it isn’t erupting, that is…

  11. Fascinating, Carl. Shame I can’t hang around long enough (in geological time) to see what happens.

  12. This is a really great article. Very clear and information-dense.
    Microgripe: can the location of nishi be put on the maps?

  13. Intriguing hypothesis, Carl.
    Could the same geological process be used to explain Iwo Jima with its ludicrous uplift?

    • That would be the item of a whole other article, spoiler though, you can see Iwo Jima on the maps that Andrej produced, it is much smaller than Nishinoshima is.

      • Nishinoshima is bigger than Iwo Jima (in volcanic terms)?

        Didn’t Iwo Jima do a VEI 8 at some point in the distant past?

  14. Could you explain the seismic plots in a bit more detail? What should I be looking at to understand the reasoning a bit better. The area of interest seems to be the least prominent in the picture.
    Another question, is the graben, the result of back arc stretching?

  15. Beautyful shot of the grey andesite lava rivers. The dark steaming lines are active hot flows.
    Nishinoshima maybe one of the worlds ”hottest andesites”, temperature is important too. It erupts ar at viscosity Thats similar to Heklas andesite flows.
    Nishinoshima forms rivers but always rough Aa lava. Viscosity is still higher than all basalts. Probaly is 1060 C for Nishinoshima. It never forms any smooth surfaces in closeup. Tarso Tousside stratovolcano africa, seems to have Identical viscosity to Nishinoshima, same kind of Aa lava tounge shapes. The ground in Nishinoshima is a terrible nightmare of loose lava rubble called
    ”Aa clinker” terrfying when you falls and stumbles on that type of terrain

    Carl If Nishinoshima continues to erupt, and hotter materials from depth arrives
    Will we see transformation to true basalt soon? For now it continues to spew out the same viscosity

  16. Hi Carl,
    Glad to see you writing this article.

    Nishinoshima is close to Iwo Jima. Is the volcanism related? Iwo Jima is not a small volcano either.

    • There is an microplate caught by the split. It broke off from the Philippine plate.

  17. Do we see the precurser of an eruption in iceland now? All hell is breaking out now.

    • Aviation colour code is still at green, though it was put up to yellow for a while when this episode began a few months back, so Almannavarnir et al. not (yet) greatly concerned.

      • was that one mag5 tectonic quake and then a bunch of aftershocks, or something more volcanically interesting, any opinions on the plots ?

  18. Great Scott, it’s like a rash of measles on the chart! I’ve not seen that happen before in the peninsula. Hope the residents are not too unnerved.

  19. Friends living 30 km west of Reykjavik said the were kept awake from the M5

  20. I’m wondering if harmonic tremors have been been detected in the seismic swarm in Reykjanes Peninsula yet?

    • Note that any dot with a gray outline represents an unconfirmed quake. Upon manual review these will be relocated or removed. Those that survive the manual review will then be plotted with a black outline. In this image we see that so far only the stars have black outlines. In the end most of the dots will end up very close to the stars.

      • ‘manual review’ – I’m sure someone at IMO will have the coffee mugs lined up this morning ready to stare for long hours at a screen.

      • Tomas Andersson

        Did you knew that Grimsvötns upper magma chamber is just 1700 meters below the lake floor?

        Making this possible the most shallow magma resovair in entire Iceland!
        But I knows that magma resovairs tends to be very shallow at Spreading ridges

      • I think an open conduit is forming to the surface in Grimsvötn.
        The 2011 arera have since 2018 become very hot and Sulfur ridden. Inflation is increasing too.
        IMO reported very large Sulfur emissions earlier from 2020.
        The large sulfur emissions are signs that magma is very close and shallow to the surface now.
        The Ice shelf is also melting in the 1998,2004and 2011 arera. In 2020 I think they measured
        + 80 C in the water in an arera very close to the caldera wall

        Thats signs its very close to surface now

        We have a very diffrent Grimsvötn today 2020 compared to before 2011

  21. Very shallow quakes in Katla. Melt water contacts hot rocks gives steam explosions?

  22. Might I ask the experts if the current large seismic upheavals at Tjornes and Reykjanes are the likely result of the (approximate) 120 year cycle of Icelandic eruptions? I know we are supposed to be entering the peak period of activity, assuming the cycle to be valid, and the wheels have not dropped off it.

    I am imagining the up-welling magma pushing and shoving a bit at the underside of Iceland. To that end, we ought to be seeing some eruptions arriving before long. I trust this is not too school-boy level of thinking!

    • Also an amateur, and I agree, Increased alternating activity at Rejkyanes and Tjornes and most recently at both regions simultanously. Seems like a running up for something… Would be interesting to get some thoughts from the experts…

    • One needs just to look at the past history of volcanic eruptions in Iceland, to get an answer to that question.

      In 1862 (about 160 years ago) there was a minor rifting event SW of Bardarbunga. Then in 1875 Askja erupted in a very large eruption, which started as a larger rifting eruption, between Askja and Krafla. The two decades that followed saw several small sized eruptions of Grimsvotn. Then almost 30 years after the Askja event, there were larger eruptions at Bardarbunga and Grimsvotn in 1902 and 1910, and a few more smaller eruptions at Askja in 1920s, and then things slowed down. Interestingly this marked a period when Hekla was dormant but two eruptions occured near Hekla in 1878 and 1913. An eruption of Katla (1918) happened towards the end of this period. If we consider this peak between 1862-1918, then the whole maxima lasted for about 56 years.

      In the previous cycle, around year 1710 (so 165 years earlier), Vatnajokull experienced many eruptions of Grimsvotn, a few near Bardarbunga (1716, 1717, and 1726), a rifting episode at Krafla (1724-1729), one eruption at Oraefajokull, one at Kverfjoll, all within 30 years. Things were quiet after that, but with 3 remarkably large eruptions in the next 100 years, one from Katla in 1755, one from Hekla in 1766 and one from Laki in 1783 (which was followed by a rifting event, without eruption, at Hengill). If we consider the period between 1700 to 1730, then the whole maxima lasted for about 30 years. The decade of 1720s was very active.An eruption near Hekla also happened in 1725, during the time of highest volcanic activity during this period.

      Eruption record becomes scarcer in the medieval times. We need to backtrack around 220 years to reach another flood basalt event, at Veidivotn in 1477.

      160 years before that, was around 1320. This was when another flood basalt event occurred from Bardarbunga, near Askja (Frambruni eruption). The dating of such eruption in not certain.But some 40 years into this period, one of the largest volcanic eruptions in Iceland also occurred, at Oraefajokull in 1362.

      160 years prior was around 1160. This matches very well with the previous large fires in Iceland, from Krusivik that started from 1151 and continued for some time. Reykjanes fires started around 1210. So this period of heightened activity might have lasted around 60+ years.

      And if we track back some 200 years we reach the period around 950. Around this time, there were several large efusive eruptions in Iceland: Edlgja in Katla, also a shield volcano eruption near in Langjokull, and a few others.

      If these past cycles can teach us something, is this:
      – Around every 160 years (but sometimes a bit longer), a period of increased volcanic activity happens in Iceland, probably linked to the plume/hotspot. The next maxima is around now.
      – Two cycles will not be similar. Things will happen in very different manners but, learning from the well-documented past two peaks, we can expect a period of around 30-60 years with heightened volcanic activity, especially around Vatnajokull. The periods in between (around 100 years or more) are usually quiet, with relatively few eruptions in Iceland.
      – This period usually sees 1 or 2 very large eruptions in Iceland, usually rifting events (but sometimes also explosive eruptions. The eruption of 2014 in Holuhraun was probably our first in this cycle. Therefore another rifting event could occur in the next decade or two.
      – Volcanoes that are usually quiet (Askja, Krafla, Kverfjoll, Oraefajokull, Reykjanes, Krisuvik, and eruptions in the vicinity of Hekla) are far more likely to erupt during these periods. So let’s expect some of those ones. The eruption history for Bardarbunga and Grimsvotn is highly correlated with these periods. But Katla and Hekla do not seem to erupt in tandem with these hotspot maxima.

      • I am obviously fitting a pattern into the historical list of eruptions. So, in good scientific manner, please take my conclusions with a grain of salt.

        I am trying to catch the large rifting events of 934, 1151, 1320, 1477, 1720s, 1862/1875, 2014, into a regular pattern.

        Option A: I can fit a regular period of 140 years:
        900, 1040, 1180, 1320, 1460, 1600, 1740, 1880, 2020 (7 events fit with this pattern, fall within 30 years of these dates)
        Or Option B: I can fit an irregular period of 160 years or sometimes longer (as I did before), as I did in my former comment:
        950 … 1157, 1317, 1477 … 1700, 1860, 2020 (7 events fit with this pattern, fall within 20 years of these dates)

        The problem with the 140 year regular pattern is that I do not find any significant eruptions around the dates of 1600 and 1040, but obviously medieval records are scarce then.

        Whatever I do, Laki 1783 event, does not seem to fit into these patterns.
        And whatever I do, we seem to be heading towards a new plume peak of activity.

        Any comments?

        • Using your first set I get a 180 year periodicity (mean), with a 95% confidence interval of 147.7 to 212.3 years.

          Treating “1862/1875” as a single event at 1868.

          Using M$ Excel, so if the correct answer turns out to be “potato” don’t be surprised.


          Unrelated side note. I got anxious and harvested my first Carolina Reaper pod tonight. (not fully ripe) Slicing it into quarters, I put three slices in a jar of pickled eggs (adding dill and fresh boiling vinegar) and ate the 4th slice. Bugger has got some zip! Imagine when they become fully ripe. 😀

          In the front are Carolina Reapers, behind that are Ghost Peppers. (aka Bhut Jolokia)

          • Side Note. “Confidence Interval” just means that the likely actual number has that likelihood of being within that range.

            Setting it for 99% conf interval, extends the range to 137.4975156 – 222.5024844 years.

            (don’t get caught up by the precision of the numbers, it’s still arbitrary and does not signify any greater accuracy or relevance . I was always taught that if an algorithm spit it out… to state it. If you round it to 137.5 – 222.5 years, that would be fine)

          • I like chillies, but you are certifiably insane!
            On another topic there is another way to handle these stats, if you have the numbers to hand. A 95% confidence limit is pretty arbitrary and in my experience for poor/irregular datasets amongst friends its better to have a much weaker criterion say 75% because otherwise you smear out irregular periodicities The question to ask can be reversed, that is look at all periodicities in 10 year steps from 100 to 200 years and ask what is the probability that this periodicity is correct given the figures. Personally I think considerable mungling of inaccurate and not-existent data is required to get a really useful result.

          • Living in Scotland is not a good place for chillies. But I do love them.
            I have spicy paprika growing as a pot plant indoors, and I have now 3 fruits growing. Happy about it 🙂

            It’s good to see your comment about the 180 year periodicity.
            This means:
            968, 1148, 1328, 1508, 1688, 1868, 2048
            It certainly fits the data quite well, which would be the rifting events of:
            934 (event started 34 years before)
            1151 (very close to date of rifting event)
            1320 (estimated dating for Frambruni eruption)
            1477 (event started 31 years before)
            1508 (no events occurred, or there is lack of historical records)
            1688 (most eruptions seem to have started 20 years after this date)
            1868 (very close to the dates of Askja and Bardarbunga events)

            The data seems to show that the 180 year is slightly irregular, varying as you said, possibly within a period of 150 to a period of 210 years.

            This means the next maxima should be anytime between 2018 and 2078, with a high likelihood of a peak during the 2030s, 2040s and 2050s.

            This period of increased activity seems to have already started around 2010. So I am estimating that this peak will continue until at least 2040, and possibly even longer. The next decades will be quite active in Iceland.

          • No. But I have enough experience with super hots to know how to use them. After they mature, they will go into the smoker for 18+ hours in hickory, then when fully decicated, they get powdered to use in gumbo or jambalaya.

            The difference is that in the past I have only processed generic Habaneros like this. Using Ghosts and Reapers should ramp up the heat a little.

  23. In addition to my previous comment (on the 160 year cycle of increase in activity from the Icelandic plume), I also think that a new cycle of eruptions will start in the Reykjanes peninsula. We might see, what is known in Iceland as “fires”, or an efusive eruption, starting in some spot in Reykjanes peninsula, then a few decades later, moving into another part of the peninsula.

    Most likely location for a start is somewhere between Eldey (Reykjanes tip) and Krisuvik.
    Cycles tend to start east and move westwards. So a first eruption might happen actually at Krisuvik or Blafjoll.

    There was a post about this some months ago in VC.

    • Don’t know anything about the different time pattern which you see or not. But as Einstein explained, time is relative and an earthyear wasn’t always 365.25 days…

      But you may could explain me what’s the “0” on the GPS data IMO page, which will exist sometime after 2014 (or before?):

      http://brunnur.vedur.is/gps/thorbjorn.html

    • Irpsit, Thanks for your historical resumé. The “rifting”, is that connected with the plates moving, leaving a weakness so the plume can push through? In that case the eruption periodicity perhaps depends more on plate movements than on variations in plume activity.

      • There is no reason why a system that ought to be aperiodic actually becomes periodic because feedback mechanisms often produce periodicity. After all 150 years is quite a long period suggestive of very large masses or very low returning forces. Some geysers are very periodic and in a sense this is just a very big geyser running on gas and liquid rock rather than water and steam (sas and liquid).

  24. The compositon of Nishinoshima magmas seems to be a Basaltic Andesite: like Anak Krakatau
    But it coud be a hot Andesite too.
    Its behaviour is similar to anak krakatau

  25. big quake up in alaska 7.8 at 13km depth – dunno how far that is from where Motsfo is living, but the shake intensity looks pretty high – so hope everyone is safe. beachball and stuff in the link below (or presumably direct at usgs)

    https://earthquake-report.com/2020/07/22/massive-earthquake-alaska-peninsula-july-22-2020/?fbclid=IwAR2eQznEhdeoc3sSAJXIPfmsr4MO9l5wB9DpRZTHkwbQLOgXeUnG9afyPD8

    i suppose if you’re looking for quakes triggering eruptions – then you have a couple of weeks for Veniaminof to pop 🙂

      • The tsunami warning was lifted. No significant tsunami has been observed.

      • Question for you Albert. Further to my last question on the possibility that a submarine eruption was a possible 536-540 second eruption. Does Ninoshima fit the bill for the second? It would seem to small but if this is the start of a mantle plume then…

        • It seems too small to me. The size of the plateau is a few square kilometer, and the caldera cannot have been larger than that. Iwo Jima is larger: it a very similar system on the same chain, and had a major explosion 2000 to 3000 years ago. However, that is too early for us.

          My feeling is that we are looking for something on the Aleutian arc, that it is already known but not accurately enough dated. But that is just a guess.

          If you want to read more on Iwo Jima, see https://www.volcanocafe.org/iwo-jima-in-45-eruptions/

  26. IMHO, the aftershock zone around the latest Reykjanes swarm under the WCent tip of the Reykjanes tip is the largest we’ve seen so far in the current multi-month sequence…and extends in all directions in a rather curiously uniform manner. If these aftershocks are tectonically induced, then the spatial coverage of the aftershocks is indicating the area is becoming/is a jumble of fractured rock…most likely from the crustal stretching and thinning from extensional faulting around the MAR.
    Each of these aftershocks is likely indicating a further weakening of the surface crust, and with an active magma reservoir underneath, it seems almost inevitable that the fractured roof is going to let loose somewhere eventually, leading most likely to a magmatic rifting event. Starting with the Bardabunga/Holuhraun rifting and subsequent eruption, the timescale between it and other now-significant rifting events in the north and south of Iceland is so small that (IMHO) they must share some type of a common “clock”….i.e. the never changing spreading rate across the MAR?
    Like the San Andreas Fault near Parkfield where a “clock” is clearly in play….(accumulated stress reaches a quite specific critical point which is enough to overcome the intrinsic stiction of the fault and an earthquake occurs (~ 22 yr periodicity and always a 6.0 magnitude), the crust in Iceland can withstand just so much stretching until it finally begins to structurally fail leading to increases in volcanic and rifting activity at ~ 160-180yr. intervals instead of the 22yr periodicity seen near Parkfield (ignoring that the fault mechanism(s) are quite different).
    So I guess what I’m leading to is that I vote for tectonics (steady-state crustal spreading) as being the root “clock” for Iceland’s ~ 160-180yr. seismic/volcanic cycle, and not so much a cycle in the mantle plume (though I’m sure they are interrelated given that both occur rather simultaneously and the “cycle” has been going on for many millennia).

    • It’s the question of chicken and egg. Who came first? Hotspot or the MAR? Volcanism or Tectonics?

      We have a fantastic coincidence, a major hotspot located right in a spreading ridge.
      Was the hotspot the original cause for the spreading ridge that began between the Eurasian plate and the North American plate?
      Or did the spreading occurred first and the hotspot emerged because of that weakness?

      If tectonics rule the show, then magma is just filling the gaps, when it has the change.

      • Hasn’t the Icelandic hot-spot left a trail from NW Greenland, diagonally across there, then out into Atlantic ??

        I vaguely remember there’d been a ‘hammer & tongs’ argument between rival supporters of hot-spot’s possible routes prior to dry-foot on Greenland…

    • Thanks Craig! The constant spreading as a driving clock! A good explanation for the periodic volcanism. Much harder to explain a periodic plume activity. And we know so much less about the plumes.

    • Please, do note that the uniform extension of aftershocks in all directions is made up by unconfirmed quakes. Once manually verified and relocated, they all line up very consistently along what could be a single fault line. The strike is a bit more E-W alinged than the SW-NE that we usually see in the area, so maybe it’s a combination of many shorter segments. Anyway, it’s nothing like the huge blob of dots that we see on the IMO main page.

      The automatic quake detection system always does this. Whenever there is an intense swarm, the system gets overwhelmed and generates lots of false detections and poorly constrained locations. You can recognize unverified quakes by the light gray outline around the dot. In the list, anything less than 99 in the quality column has not yet been manually checked.

      Check out the link below for a plot containing only verified quakes:
      https://skjalftalisa.vedur.is/#/page/map

  27. Hi Albert I dont want to fill VC with my annoying commentary

    But How large will Nishinoshima become? whats the current yearly magma supply? Will the magma become more basaltic If this continues?

    Even if it stops now, the Island is going to last a very long time. Nishinoshima is a good sized land addition now.
    This is a rather large eruption as Carl says

  28. One more first about the Reykjanes ridge: it is halfway between a spreading ridge (plates move into opposite direction) and a transform zone (plates slide one past another).

    This means that activity here often alternates between purely tectonic times, where there are no volcanism (from the 14th century until now) and times where strong volcanic activity and rifting takes place (between 9th century and 13th century*). This also seems to be cyclical, about every 800-1000 years or so.
    We might be heading into another of those volcanic periods in the Reykjanes.

    * During the period that Reykjanes was active, activity in Vatnajokull (namely Grimsvotn) and in Hekla seemed to have been particularly low. This was explored in a scientific paper (which I cannot remember the title), where it stated that Reykjanes takes up for the rifting that would normally take place in the EVZ (Eastern Volcanic Zone) and South Volcanic Zone of Iceland. The rifting alternates between them.

    However things are more complex than this. Reykjanes peninsula was highly active between year 900 until around 1300. The eruptions were originally further east, then moved further west. Interestingly Hekla was dormant for centuries until 1104. Katla had a very large eruption, Eldgja, in 934 (which was around the beginning of this period). Then Katla was dormant after 950 until 1150 (200 years!). Clearly, between 950 and 1100, we have a period of 150 years where Katla and Hekla were unusually dormant, when activity started at the West Volcanic Zone (WVZ), namely Langjokull, Hengill and Reykjanes peninsula.

    Interestingly, there was one large rifting event at Bardarbunga around 870, but then no more rifting events after that (when Reykjanes peninsula was volcanically active). Activity in Bardarbunga only resumed in 1320 with a large rifting event, when the activity at Reykjanes peninsula became dormant again. After that, Bardarbunga had one more major rifting event in 1477.

    There is a pattern seemingly at work. And tectonics (and the switch between WVZ and EVZ) seems to explain it very well.

    • What I want to say is that we might see the last large eruptions of Bardarbunga and Grimsvotn, and from Katla, before all these volcanoes go dormant, together with Hekla, for a few centuries. And at the same time, activity in the West Volcanic Zone (between Langjokull and Reykjanes) comes back to life.

      But this is a slow process, that takes decades, and too long-term for us humans to pay attention to.

      I think what we would need would be an estimate of the spreading (in cm) that took place in Reykjanes every century since settlement. And also in the South/Eastern volcanic zone (Katla, Hekla, Grimsvotn, Bardarbunga). If we see a long-term slowing down of tectonic movement in one system, and an increase in the other, then we know that this transition is taking place.

      This is probably possible when we have decades of GPS record in both regions of Iceland.
      It would make a good PhD thesis…!

      • Whats your opinion on this Irpsit

        I think an open conduit is forming to the surface in Grimsvötn. The 2011 arera have since 2018 become very hot and Sulfur ridden. Inflation is increasing too. IMO reported very large Sulfur emissions earlier from 2020. The large sulfur emissions are signs that magma is very close and shallow to the surface now.
        The Ice shelf is also melting in the 1998,2004and 2011 arera. In 2020 I think they measure 80 C
        in the water in an arera very close to the caldera wall

        Thats signs its very close to surface now

        We have a very diffrent Grimsvötn today 2020 compared to before 2011

        Very large sulfur outgassing been reported from Grimsvötn earlier this summer: a sign that magma is extremely close to the surface

        • Extremely large Sulfur Emissions now from Grimsvötn
          Was not there 2018
          Very Intresting!
          The largest Sulfur emissions known from any sleeping volcano

          • Grimsvötns current magma is probaly close to 1180 C or above so its very hot and fluid. it haves low viscosity, as low as kilauea. The gas in Grimsvötn lowers viscosity too, just as
            High temperature and low sillica do.
            Maybe hottest magma in Iceland?

            Grimsvötns hot magma is mainly sulphuric gasses.
            This means that the lava itself is not very explosive, and that without the water in the sub-glacial lakes, and the glacial ice, Grimsvötn would during eruptions produce lava fountains 700 to 1700 metres high.

        • My opinion is that we know little about volcanoes still. At least I know little.
          Sulfur outgasing can be a sign of an approaching eruption, but it can also be just outgasing.

          Grimsvotn probably had already an open conduict to the surface before. Usually, its eruption do not have that many earthquakes before, which means that magma has an easy way out. Like Hekla.

          We do not know how and when Grimsvotn does a very large eruption, VEI5 or VEI6, which it can.

          Overall, I expect Iceland to produce more large scale rifting eruptions and shield volcanoes, rather than mega-explosive eruptions. And that’s why one should pay attention to the behaviour of the central volcano, as it is where action can start (at least we learnt that back in 2014!). Oraefajokull is an exception, because of a different magma composition.

          I say one more thing. Laki was extremely sulfur rich, and that one is directly linked to Grimsvotn. So, it’s rather normal to see Grimsvotn doing that, especially as its magma is now very fresh one. 2011 had a much fresher magma composition than the previous eruptions. For the first time in along while. Likewise for Holuhraun. Which is a sign that across Vatnajokull and probably Iceland, volcanoes are being recharged with fresh plume magma.

          • Yes and be not supprised If we gets a surtsey – phase in the caldera of Grimsvötn and later a shield – tuya If its a long lived eruption. 1996, 1998, 2004 and 2011 never went beyond small tephra islands in the meltwater lake when they calmed down. Next time maybe more long lived?

            Sulfur is signs that magma is very close to the surface.
            Very large sulfur emissions from Grimsvötn now in 2011 arera: Coud be a vent thats about to open up.
            The 2011 area caldera wall is also very hot now.
            But coud just be degassing .. But magma is very shallow.
            Upper magma chamber is just 1700 meter below Svianukur

    • Most eruptions in iceland are from the east volcanic zone. A periodicity in eruptions is effectively that of the EVZ. The WVZ and Reykjanes do not show a 150-yr (or so) period, but something more like 800 years. Can we make sense of that? The spreading rate of the WVZ and Reykjanes are about the same, and are about three times less than that of the EVZ. The crust is twice as thick in the EVZ (admittedly it varies). How about the buoyancy force? After spreading by an amount x, the upward force from below is F=(density)*g*x*h , where the density is that of the crust (2 000 kg/m^3), g is the gravitation acceleration, and h is the thickness of the spreading rift. This force builds up per year, at a rate that is 6 times larger in the EVZ than in the WVZ and Reykjanes. If the crust is equally strong, the breaking point is reached 6 times as fast on the EVZ. 6 times faster than 800 years is 130 years or so. I have no idea whether this is indeed the mechanism but it seems possible. Do note that it is hard to get an accurate time scale from irregular events, certainly with only limited data.

      Alternation is also an issue. The Halmundarhraun lava field and the Eldgja lava were erupted fairly close in time. The first is at the norther end of the WVZ and the second at the southern end of the EVZ. Telling.

      • Thanks Albert, so with all these additional factors in play, the steady pull of the plate spreading would still be the driving force in the clock behind the periodic eruptions

  29. You guys are forgetting the original reason for the article… Nishinoshima. Let’s get back to that, please. Even though Iceland talks are nice as well, but not in the middle of a discussion about Nishinoshima.

    Here are some questions from Jesper Sandberg

    22/07/2020 at 18:05

    Hi Albert I don’t want to fill VC with my annoying commentary

    But How large will Nishinoshima become? whats the current yearly magma supply? Will the magma become more basaltic If this continues?

    Even if it stops now, the Island is going to last a very long time. Nishinoshima is a good sized land addition now.

    This is a rather large eruption as Carl says

    • None of these questions can be answered! We don’t know why it suddenly became so active. Two similar cases are Bagana and Anak Krakatau, which went from nowhere to perpetually active because a large magma chamber had suddenly become available, in both cases after a massive nearby eruption. No evidence for that here, but we can assume the a conduit suddenly opened up to a previously formed magma chamber. Magma chambers are large and this can go on for a long time without making a dent in the chamber. Don’t confuse eruption rates with magma supply rates. For the same reason (a large magma chamber) I would not expect a dramatic change in the lava properties. Is a plume forming? I don’t think so (unlike Carl). Subduction zones are not good territory for plume formation (not impossible, but adverse conditions), and this volcano belongs to a long chain along the subduction front and that is not typical for a plume. Note that the size of the undersea mountain is typical for the chain – there is nothing special about this volcano apart from its hyper-activity (but don’t forget Iwo Jima, along the same chain). The activity suggests a very shallow magma chamber formed not so long ago. The graben formed by the (steep?) subduction indicates that magma chambers can form here quite easily

      Why so many volcanoes along this line? The Philippine plate is rather young and warm, so could melt quite easily. I think the magma source is not the problem here. The question lies in what cleared the conduit.

    • Looks like a normal fault opening up. Not sure if I got my faults with my faults figured out correctly

    • Not to be rude but isn’t that techno-speak for “something seems to be happening, but we are not quite sure what just yet”?

  30. Back to the japanese Islands. South, in the same back arc as Nishinoshima is Iwojima. On Google map it seems that it also had a flank collapse wit a massive landslide. Cannot however find any information on this. someone her who knows? In the atlantic such volcanic flank collapses (in the Canarians for example) are known to have caused hughe tsunamis. are there any risk for this if Nishinoshima collaps again? Still pressing on with its eruption. Ash cloud at 3700 m (12000 ft) this morning.

    • I don’t see a flank collapse at Iwo Jima. The structure in the ocean basin there seems because that track has been mapped in detail and the rest is much lower resolution.

  31. USGS reports two earthquakes in the Izu Islands region with magnitudes of 5.8 and 4.7. Can’t quite make out how close or far they were from Nishinoshima, but it may not be coincidence.

    We’ll see if more is afoot in the region…

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