Taupo Tapping Away

The drop dead gorgeous Lake Taupo inside the Oruanui Caldera of Taupo Volcano. Photograph by Bo-deh.

Taupo is one of those volcanoes I do not like to write about in Volcanocafé. It is one thing to write a historical retrospect of what it has done in yon olden days, and something completely different when it is doing something interesting.

The reason is simple, Taupo is one of those volcanoes that have the word “super” attached to it. It is both a super-erupting volcano and a super-volcano. Most volcanologists do not like the phrase super-volcano, but I do not have any qualms using it. It has a certain descriptive panache to it.

After all, that super-suffix says it all, these are not the volcanoes you want to be around when they go off with gusto. That being said, far from all eruptions from a super-volcano are big, far from it.

I should also here probably state that the Taupo Volcanic Zone is one of the volcanoes I work with professionally, obviously I do not work for the GNS (Geological Survey of New Zealand). I work for a private company that has other volcanic interests there. So, by necessity I have to know a lot about the volcanoes on the Taupo Volcanic Zone.


The News

Image from GNS.

During the last couple of years Taupo Caldera has been inflating, mainly at the Horomatangi Reef at the Western side of Lake Taupo.

This is a resurging dome on top of the main magma reservoir. I have interpreted this as influx of fresh magma from depth into the reservoir in combination with heating of water-carrying layers under Horomatangi Reef.

This increase in pressure has caused smaller swarms, but not enough to write about really. But it merited lifting the volcanic alert level from 0 to 1.

This is when volcanologists decide to look at things with a bit more interest since the volcano is doing something unusual that may, or may not, lead to something in the future.

At 23.37 local time on the 30th of November an M5.6 earthquake occurred at 9km depth under the southern part of the Horomatangi Reef.

This has been followed by 200 aftershocks, with a M4.5 being the largest. There has been a general increase in seismic activity at the volcano since May 2022.

The M5.6 caused a minor tsunami in the lake that killed two slightly innocent pedalboats, no pedalboat is ever completely innocent.

Inflation due to magma, increased earthquake activity, and a larger earthquake is definitely enough for me to find it worthwhile to write an article.



Rough image of the pertinent parts of Taupo. Please note that where it states Crater and where it states Caldera it should be the other way around.
Image by ChaseKiwi.

We have previously covered the region more in depth, so this will be a short recap of the geologic setting.

Taupo Volcano is technically a resurging large caldera volcano situated inside a larger volcanic field called the Taupo Volcanic Zone, which spans from Whakaari (White Island) all the way to south of Taupo itself.

It contains famous volcanoes like Okataina, Rotorua, Ruapehu and Tarawera, just to name a few. TVZ is an intra-arc volcanic rift producing basalts as base magma and it is historically among the most prolific large eruption centres.

The rifting is at it’s largest at Taupo (around 8mm per year) and diminishes towards the north. Previously the spread rate was higher to the north, and several large calderas formed there during VEI-7 and VEI-8 eruptions.

But as the spreading increased to the south and to Taupo it gradually became more explosive, and it started to erupt rhyolite in ignimbrite eruptions around 100 000 years ago. For the first 200 000 years the volcano was more benign, but benign should probably be taken with a pinch of salt. Everything is relative after all.

26 500 years ago, Taupo entered the big league with the VEI-8 Oruanui Caldera Collapse. It caused 430 cubic kilometres of pyroclastic fall deposits, 320 cubic kilometres of pyroclastic density current flows (ignimbrite base surge), and a further 420 cubic kilometres of intra-caldera material. All of that is equivalent to 530 cubic kilometres of rhyolite magma.

In the year 232 came the very violent Hatepe eruption. At 120 cubic kilometres of material, it is the second largest eruption in the last 5 000 years after the 1628BC destruction of Mount Aniakchak that came in at 150 cubic kilometres.

Hatepe was unusually explosive with 25 percent ejected in mere minutes, another trait it shares with Aniakchak.



Horomatango Reef is very important to the Iwi. Any larger eruption here would sadly destroy a lot of cultural artifacts, among them this stunning rock carving.

Thankfully it takes quite a bit to get volcanoes of this size going, especially after a prolonged nap of 1 800 years. This means that it will take a bit more for an eruption to occur.

Here it is good to remember one thing, it is in the job description of large volcanoes to erupt now and then. It is up to us mere mortals to figure out when it is time to be somewhere else. It is therefore important to follow any advice or evacuation order from the competent authorities. In this case that is GNS.

If they say it is time to head out, you do not ask yourself if you should bring old Aunt Agatha’s Saxophone collection. No, instead you open the door and start to galumph as hard and fast you can in the recommended direction.

Anyway, we are not at the galumphing stage yet. All we know is that the volcano has indigestion and is moving towards an eruption that can come in a few weeks, or in a few years. It may though be a good idea to have your essential papers, medications, and some empty water bottles handy near your door for the next couple of decades.

After all, better to be prepared and nothing happens, compared to wonder where your heart medication is when you need to run like Usain Bolt…

What I am trying to say is that sooner or later Taupo will erupt, but right now it is up to volcanologists to watch it, and for you to go about your day as per usual. After all, Taupo could go back to sleep for a few hundred years. We are not beyond the point of no return.

So, you are curious about what an eruption would look like? We need some figures for that.


Figurative beast

Thankfully we have a pretty good record of all the eruptions in the last 10 000 years at Taupo, and since all eruptions are not equal it is good to look at the sizes, and how many they have been in each size-bin.

The smallest one in the record is a minor VEI-3 at 0.01 cubic kilometre. I will add a reference eruption for each size. And even though it was 26 500 years ago I will chuck in Oruanui for good measure in the statistics.

VEI-3     8             0.01 – 0.09km3                 Hekla 2000

VEI-4     10           0.1 – 0.9km3                     Eyjafjallajökull 2010 & Grimsvötn 2011

VEI-5     2             1 – 9.9km3                         Cerro Hudson

VEI-6     0             10 – 99km3                        Pinatubo, Hunga Tonga

VEI-7     1             100 – 999km3                   Thera, Tambora, Aniakchak

VEI-8     1             1000km3+                          Toba

It is here good to remember that out of 22 eruptions 20 was of manageable size with 18 being more of a nuisance that you just do not want to be around. A VEI-5 is something that you definitely do not want to be around since it can produce pyroclastic base surges that travel up to 50km.

That there is no VEI-6 is debatable, one of the VEI-5s was so large that it is likely to have been a small VEI-6, it is not easy to get the figures exactly correct after thousands of years of washing away of the evidence. But I will leave it as is.

For a VEI-6 it is a very good idea to be further away, not all of them are as nice as Pinatubo, Hunga Tonga packed a far larger punch since the eruption was short in its penultimate explosive phase.

Even though volcanologists are getting better and better at forecasting when an eruption will occur, we are not good at knowing the size of an eruption in advance.

Now we come to repose time. Many volcanoes tend to have a larger eruption after a long nap. And we know that Taupo tends to be cyclical with periods of dormancy and periods of heightened volcanic unrest.

Are there any patterns there?

3 eruptive periods started with VEI-3 eruptions, we have 3 VEI-4 starters, 2 VEI-5 starters, and no known larger first eruption in the period.

I would though not really trust this with my life, there seems to be a trend towards it being able to start with any size, and the statistic material for the big ones is to small to say anything at all. In other words, it could be any size.


Would I go to Taupo?

Two pedalboats that did not survive the lake tsunami.
Image from Taupo Pedal Boats.

I think the best question to ask is if I would go there right now? Yes, I definitely would, and in fact I am going there come spring. Well, down under it will be fall, but you catch my drift.

After all, dealing with huge honking volcanoes is my line of work, and it is an awesomely beautiful place.

But, if I see anything I do not like, or if GNS tells me to go, I will be the one galumphing first in the heard towards anywhere else far away.

Trust me, when an eruption will be around the corner it is not one of those nice Icelandic tourist eruptions that you travel to.

A sizeable VEI-5 can kill you up towards 50km, and a VEI-6 with a pyroclastic base surge will kill everyone within 50km and may kill you at 100km. You do the math for anything bigger yourself, it ain’t gonna be pretty up and close.


147 thoughts on “Taupo Tapping Away

  1. I was seriously considering going to New Zealand mid next year, renting an electric car abd driving to see Taupo and Rotorua, until my financial situation changed 🙁

    But maybe it is fir the best I try a little bit later… even if it is a small eruption being on the lake or its shores is probably a very bad idea if even just quakes are able to make dangerous waves.

    • Northen New Zeeland have a Subtropical Oceanic Climate so will be pretty mild in winter and only high peaks gets snow.

      Auckland is pretty much the mildest nicest climate there is out there, but Taupo is higher up and cooler. NZ is not a winter adapted country like Canada

  2. New Zealand is fascinating. It does not do things by half. Mauna Loa announces itself with an M4, Taupo answers with a full magnitude more. The reef is the likely location for anything eruptive. But there hasn’t been any increase in hydrothermal activity, has there? So nothing imminent. But you don’t really want a tectonic event of this size next to an inflating magma chamber!

    • It was at the bottom of the reservoir to be exact.
      I find it to be a bit of odd location.

        • I think it is a tad more to the south where there is a fauly exactly at the Oruanui caldera outline that runs across the lake.
          Expansion/compression quake, but I should need to check it when I get time.

          • I initially thought that the location was right in the center of the hatepe caldera area, which would have indeed been a very strange earthquake given the depth. If that had been the case, would have placed it right in the center of the aseismic crystal mush pocket.

            Makes a lot more sense that it’s more of a ring fault quake, although the depth is interesting.

  3. Nice update: and some of Taupoian eruptions have covered almost all of the North Island by Ingmigbrite sheets like Kidnappers Deposit .. so its an insane volcano really

    The supply per square kilometer is not the most intense in the world, but TVZ haves as a whole arera a very large supply

    Is there any signs it coud erupt now ?
    Hunga Tonga Was insane too with pyroclastic flows flowing 80 km underwater

    • Oruanui was scary, can you imagine how violent an eruption it must have been to blast through a long-lived lake at different vents and then collapse the land adjacent as well as the caldera? Virtually everything in the North Island was wiped clean. TVZ doesn’t seem to have too long a build-up between large events either.

  4. Going off the USGS site it’s the 2nd largest quake inside the caldera since a M6.2 in 1999, which was on the west side.
    I’d imagine modern measuring equipment has only been in place since the 80s though.

    Wouldn’t put me off going, at the end of the day if it goes off not much you can do, easier to just accept death.
    I wouldn’t climb up an actively erupting Fuego however, for instance. That’s just asking for trouble.

    • Sorry I’ve phrased that wrong, 2nd largest quake since 1900, the largest being an M6.2 in 1999.

    • The M6.2 was tectonic on an adjacent fault related to the spread center, so this was the largest volcanic origin earthquake that we know of to date. If I am wrong on this I suspect Mike will correct me when he has the time to do so.

      • That is correct, it’s the largest quake on record in the lake/caldera area itself.

        Another interesting question about this quake is that nobody seems to have been able to publish a confident MT for the focal mechanism yet – and I think you will know why, Carl. USGS, for instance, have the usual Mww magnitude, but have not issued a MT solution, which they pretty much invariably do with an Mww AFAIK.

  5. Hatepe was less than 2,000 years ago, which is awful recent to throw out anything *too* large. Looking at the eruption record, it doesn’t seem like Taupo has that high a supply rate, longterm, 0.01km^3 per year of eruptible volume seems pretty generous. Taupo saves its supply for drama, but it has to be frugal for a long time. A VEI 5 though would not be *too* surprising.

    • I wants a long expousre night photograph of souch a eruption: ligthning mania .. 30 km3 per 3 th minute

      • Yeah, 170,000,000 m^3/second eruption rate is your kind of volcano! Camera survival might be a minor issue though.

        • Well, you could cover it up in a thick layer of asbestos, take the pictures, and hope that someone finds the camera afterwards and you become a hero…
          The asbestos would at that point not make any difference whatsoever to your survival 🙂

    • This is where my knowledge of this stuff falls down.

      How do we know Hatepe cleared the volcano out of its entire magma storage? Couldn’t it theoretically have additional magma that didn’t partake in Hatepe, that could be re-activated now (or at any point in the future)? How do we account for this, or is it not really an accurate question?

      I’m thinking of Cerro Azul / Quizapu here to an extent. Traditional logic would probably suggest no volcano is having two 5km^3 events 100 years apart, unless that system has a hell of a lot of magma down there and not all of it erupted the first time. Couldn’t this be true for Taupo, or any system really?

      • This is precisely what happened in the Crater Lake / Mt Mazama VEI 7 eruption that occurred around 6500 years ago. There was a VEI-6 eruption, but it turns out that the VEI-6 was actually a precursor to the main event VEI-7 eruption only 200 years later. Certainly not the norm, but you’re correct in recognizing that these things are possible.

      • Well, do not take up that bet with Grimsvötn.
        It did five VEI-5 to large VEI-6 with a borderline VEI-7 eruptions in 500 years flat.
        The Saksunarvatn Tephras is something that I would have loved to see really.
        The repose lasted basically for 5000 years after though.

      • Yes, big eruptions in quick succession can and do happen. But it also depends on the type.

        The Quizapú sequence is very particular, the first 5 km3 DRE eruption was a lava flow, this was probably driven by the pressure, or the buoyancy of the magma, it likely deflated the magma chamber, but solid rock around it has a limit to how much it can deform and flow into the contracting chamber, at some point there will be a sort of suction force from the chamber that stops the eruption. In contrast, the second 5 km3 DRE eruption was a typical rhyolite plinian eruption that was gas driven. At some point, there was probably a large gas build-up in the conduit and it blew up into a gas and pumice jet. Here the decompression and rapid expansion of the magma likely allowed to drain more deeply the magma chamber, but still the same limit to how much the rock will deform stops the eruption at some point.

        Hatepe was different. Hatepe was a caldera-forming event. The ring fault opened up, and magma blew through multiple vents along the ring fault, feeding a colossal pyroclastic flow that engulfed everything within a radius of 80 km from the volcano. The roof fell flat on the chamber, and the melt was free to escape. Presumably the entire magma chamber was destroyed, or at least I don’t see any reason why any magma would be left. Once the roof falls like a block there is no limit to how much magma can be erupted, other than the amount of magma in the volcano.

    • It is though good to remember that the magma reservoir is rather big.
      If I remember correctly there is moroe than 500km3 of rhyolitic mush down there.
      So, a VEI-6 is definitely not impossible.
      When it erupts next a VEI-4 is probably the most likely, but with one up or down as most likely alternatives with a heavy bias downwards.
      I would say that a Katla eruption is more likely to be bigger.
      That is the thing with this gigantic arsed caldera volcanoes, their average VEI is not that impressive, it is just that they once upon a blue moon do humongous.

      Atitlán is a good example, 100s if not 1000s of VEI-2 to VEI-5s, and whammo out jumps a María Técun Tuff covering everything from Colombia to Florida in a layer of ash and welded tuffs.

      • Which one of those eruptions had almost no zonation from start to finish? That infers that the entire chamber went up as one unit.

        I am unsure if this was part of the trapdoor collapse mechanism.

    • I used to think Taupo had a higher supply rate. Now, after learning more about calderas, I would go for a lower estimate. The zircons erupted in the Oruanui eruption range back to a bit over 300,000 years before present. This could suggest that the Oruanui magma chamber, started to grow in the aftermath of the Whakamaru eruption, at about 350,000 years BP, next to where Taupo is today. Thus having a slow 325,000 years build-up. In gravity anomaly maps Mangakino, Whakamaru and Taupo seem to make a complex of coalesced calderas, with Rotorua, Kapenga, and Okataina making another coalesced complex to the north. I’d speculate Mangakino, Whakamaru, and Taupo might be part of the same volcanic complex. If we look at the large caldera events in this complex of calderas since the Kidnappers Tuff (omitting earlier less studied events), and the dormancy before them, it looks like this:

      Kidnappers-Rocky Hill (Mangakino): 2,050 km3 DRE, 1,000,000 years BP.

      Whakamaru Group: 1,000 km3 DRE, 350,000 years BP. Preceded by a 650,000 year interval since the earlier caldera-forming event with an average supply of 0.0015 km3/year.

      Oruanui: 530 km3 DRE, 25,400 years BP. Preceded by a 325,000 year interval with an average supply of 0.0016 km3/year.

      So I would say the long term supply is likely around 0.0015-0.0016 km3/year. It is probably variable over time, but nonetheless is not that big, Hawaii and Iceland erupt 50-100 times more DRE per unit of time than Taupo. Even if Taupo is presently doing the largest eruptions in the planet, together with Toba and Yellowstone, the long term supply is well below that of many other volcanoes of the world. I’d say Taupo relies in long intervals of magma build-up, same as other giant calderas. That said it could throw a VEI 4-5 no problem.

      • Thats the case with most sillic systems .. slow But steady inflow of basalt feeds an expanding evolving ryholite body

        Slow magmatic supply rates yeilds sillic calderas, and very fast ones makes flood basalt provinces or Iceland and Hawaiis

  6. The scary and problematic thing with the TVZ volcanoes is that they don’t seem to do gradual. They often go from the pre-eruptive buildup to a large VEI5+ without much in between.

    I think a bigger question, and one that I’m not necessarily sure anyone can answer is how much the Hatepe eruption depleted the TVZ and if it has fully recovered from that already. For most volcanoes, I would assume they would need longer than a 2000 year period to recharge after a VEI-7 eruption. But then again, most volcanoes are not Taupo, which is currently the main vent of a proper silicic large igneous province.

    • Some 88% of products from Taupo are rhyolitic, with a few surrounding Dacitic plugs (Tahuara) to boot.
      Longer residence times are not necessarily correlated with larger eruptions, but I suppose the content (and depth!) of the current magma chamber are important factors. Oruanui magma was shallower but longer lived than Taupo (Hatepe) magma, for instance.

      • I am quite surprised that no thorough imaging has been done of the magma chamber, but if it is as big as inferred then it likely wasn’t destroyed by Hatepe (as it was prior during Oruanui).
        Rhyolitic domes were extruded in the Horomatangi Reef after that eruption…

        • There has been some thorough imaging done.
          I am fairly certain that GNS has done it.

          And I know we have some imaging, sadly I can’t share any of it.
          I have a very strict boss that would strangle me if I let out company data… 🙁

    • Me and Mike Ross have had a very long discussion about Tarawera and the lack of runup.
      Basically I do not believe in the concept of a lack of runup. There could have been several episodes of magmatic build up running for decades with quite severe earthquake swarms, and then a decade of quiet, and there comes the final little push and it went apeshit.
      Take Eyjafjallajökull that had at least two episodes before the final episode, there was roughly a decade in between those charging episodes. Without equipment and a long record it is almost impossible to know, especially without any happy volcanologists around that can keep track of it and knows what is what.

      Also, there is pretty substantial reservoir filled with rhyolitic mush, if my feeble memory serves me right I calculated it above 500 cubic kilometres when I did my survey. I have that one around at my work computer somewhere.
      And obviously GNS have it down to a T.

      • Just for sake of clarity, I don’t meant to imply there would be no runup or it would come out of the blue. More saying that there is a precedent that once the runup is over and the ice is broken, things tend to go quickly.

        Pinatubo by comparison had a significant period of venting and degassing before it truly decided to erupt big. That’s what I’m suggesting would not be likely at Taupo. Not saying there wouldn’t be inflation, earthquakes, and other signs.

      • That sort of happened just now with Mauna Loa. Several episodes of strong inflation, deep quake swarms, shallow quake swarms, in the past 20 years. Even got raised alerts but did nothing. Then the other day with no real obvious signal the roof of the magma chamber cracked and lava was on the surface in an hour.

        I wouldnt expect Taupo to be so silent, but things could still escalate quickly. And even a VEI 4-5 could be catastrophic if it erupts Hunga Tonga style, as seems to be a common mode of operation for large eruptions here…

        • I could see the EQs were increasing in number, and I started seeing a lot with negative-number depths, but I didn’t see anything delineating a future fissure. And I’d seen similar ramp-up/’nevermind’ sequences. In other words, it wasn’t time to hit Delta.com and check rates at the Waikoloa Marriott…
          There have been initial Mokuaweoweo eruptions that gave clear precursors–I believe in 1975 campers saw a red glow and rocks being ejected. And by some descriptions, between 1942 and 1949 the fissures at Mokuaweoweo fumed extensively.

      • It is not good to keep your computer next to 500 cubic kilometers of rhyolitic mush.

      • If there had been a slow runup, wouldn’t all of that nice virgin basalt that erupted in 1886 have been mixed into nasty andesite or worse?

        • Tarawera was inactive from 13000 to 700 years ago, when it erupted in the Kaharoa fissure. That was a lot like 1886 only there was still some rhyolite which was erupted, the basalt dike went several tens kf km along the ruft just as it did in 1886. There are many maat craters that way from either hydrothermal explosions or rapid and explosive degassing of the magma, or both. The volume of rhyolite erupted was a lot less than in prior eruptions at Tarawera or neighboring volcano Haroharo, and the eruption created spiny steep domes instead of flat coulee flows.

          My personal theiry is Tarawera no longer has any rhyolite, there have been lots of theories on how the 1886 eruption vould have bypassed it but none really sound sensible, not when the obvious answer is there. This doesnt mean the volcano will be quiet or effusive, the basalt is fluid but has a very high water content so is still erupted violently, not to mention the abundant geotbermal activity in the area. The big blast of 1886 was not from Tarawera, it was a maar crater forming next to it as the dike intruded the hydrothermal system and it blew up. Now lake Rotomahana is in that crater.

  7. Great piece. The last passage reminds me of the Elk in the Aniakchak piece. I looked up the volume of Thera, of course, and that might be underestimated (60 qkm) as partly lost on the bottom of the sea.

    Aside from that, New Zealand can be trusted I guess. We won’t lose Carl.

    • Well, I trust myself.
      If I do not like what I see prior to going, I will not go.
      I have way to much fun in life.
      Only volcano I do not trust is Hekla. So I do not go there.
      Nobody can forecast that bugger more than an hour in advance, at best.

      • Wise. After I had written that sentence about NZ, White Island came to mind.

      • And, remember the short–but deadly–phreatic eruption of Mount Ontake / Ontakesan, Japan in September, 2014. Nobody saw that coming!

  8. Interesting write up, many thanks!

    One thing 2022 has really taught me that whoever wrote the next VEI6 would come from a volcano few have ever heard of really is a clever person. Maybe I even read that here.

    And that eruption size is only a one-dimensional measure. Intensity (rate) matters, a lot. Past large Taupo eruptions mostly seem to have been quite complicated sequences.

  9. I was looking at the grimsvotn earthquake plot for cumulative seismic moment and noticed a couple things…
    First, the rate has significantly increased.
    Second, if you subtract the large jumps, the cumulative moment is very nearly at the same levels prior to the previous two eruptions.

    Are we almost there? Maybe another month and we’ll find out yea or nay

      • I read that as “spring is a good time for a beer”. I fully support that. As for the timing of Grímsvötn, it’s now doing regular M2+ quakes. An eruption within the next 100 days would not come as a surprise. It might very well happen that as you cuddle up against a wall in the warm spring sun, cold beer in your hand, you’ll be doing that while watching videos of a big ash cloud towering over Vatnajökull.

  10. Watching this Taupo earthquake event unfold on our spectrograms has been enthralling for this budding amateur volcanologist, and I thank you for the fascinating insights and information you provide here.

    At the moment my burning question is – is the Taupo magma chamber considered directly connected to the surrounding magma systems under Tongariro and Ruapehu?

    The reason for my asking is that we have observed some random tremor signals generated under both mountains in the last month, and now in the last 24 hours there has been a small but noticeable increase in general low Khz signal strength from the ever-present background tremor under Ruapehu which leaves me wondering what impact Taupo has had on Ruapehu.

    Back in March of this year Ruapehu experienced a period of strong volcanic tremors, and on the 16th of November there was a short burst of almost identical looking tremor signals…
    My spectrograph live stream can be found here if you are interested :


    • Longer answer is no, but they are all on the Taupo Volcanic Zone, so very secondarily connected through an aunts cousins friend…

      • Question for those who know these volcanoes better than I. Would I be correct in assuming that the reason Raupehu and Tongariro behave more like traditional stratovolcanoes is that the primary rifting from the TVZ either ends or slows down at the spot location of Taupo, thus eliminating the rifting feed source to these volcanoes?

        • I believe it must have s.th. to do with the special characteristics of subduction here and with water (Hi, HTHH):

          -This molten rock rises to the surface through the thinned crust and is either erupted from volcanoes like Ruapehu, Tongariro and Ngaruhoe or sits within the crust and heats it, and the water it contains, up causing geothermal activity around Taupo and Rotorua. The area of volcanic activity is referred to as the Taupo Volcanic Zone (see map above).

        • It is an area with more features that are not found elswhere. Suddenly the subduction zone makes a kink to the west and then, in South Island, the Australian Plate subducts under the Pacific Plate which is absolutely unusual. The reason would most probably be that the Pacific Plate is not alone here. It contains 1) Chatham Rise which was a volcanic peninsula (subaerial) in the Cretacious plus 2) Campbell Plateau which is south of Chatham Rise and supposed to be a cratonic microcontinent, thinned out though, dating back to the break-up of Gondwana. So New Zealand ist geologic history in a nutshell and very unique.

          Phosphorite from Chatham Rise

          • That map of Zealandia is reminiscent of an aerial view of Mauna Loa’s summit. I know it is not a rift. Right? Or is it?

          • ” in South Island, the Australian Plate subducts under the Pacific Plate which is absolutely unusual.”

            No it doesn’t, through most of the South Island, the plate boundary is the predominantly strike-slip Alpine Fault.

            Subduction as you describe doesn’t start until the Puysegur.

      • Maybe one day, in a million years or so, the Tongariro group will become another caldera complex too. The more northern segment was mostly andesite early on up until about a milion years ago when Mangakino caldera became active, since then it has become more rhyolite. The zone is supposedly extending south, there are some mafic monogenetic vents south of Ruapehu, and I remember reading something that the plate movement near Wellington is partly extensional although the area is not volcanic yet.

        • yeah we certainly dont want something like the Kidnappers Eruption

    • When several volcanoes are connected by a magma chamber the size might be more like Lake Toba, Sumatra, boasting at least four stratovolcanoes plus three craters in the lake, to be read here:

      Batak House, Lake Toba

      Once reading in a Carl piece (methinks) about Taal (methinks) here on VC (safe) that Lake Taal, another caldera lake, once might have had a connection to the ocean. The same might go for Taupo, Amatitlán and Toba, all very close to the subduction zone, a Pacific phenomenon it seems. Just an idea though….

    • I’m still wondering what it was that gave Carl such a distrust of pedaloes.

          • It is a Riva, Carl. You wouldn’t say that about a Riva, would you? I love them. Pedal boats? Well.

          • Reply, I am more into sailboats. But, a classic Riva converted to electric can do in a pinch 😉

  11. https://www.facebook.com/USGSVolcanoes/posts/pfbid0kKKzmLvxQNVk5oWWDN4w37aHEB2ccGYAGGZWwMQAu4ui3ZFzB9oJxo1RCbNwyMJ6l

    There has been some formal analysis on the Mauna Loa lava now. Lava is not 1984 lava, it is new, erupting at a temperature of a bit over 1150 C. So the lava is slightly hotter than the lava erupted in Puna in 2018 and about the same as at Pu’u O’o, although not as hot as typical lava erupted at Kilaueas summit. It is within the same temperature range as 1984, 1975 and 1950.
    The lava is nearly entirely crystal free at the vents and has a Mg content of 6.5%, which is typical of Mauna Loa lavas, and would explain the fluidity even though the temperature is not excessively high. This probably means the magma system is a single chamber, so that crystals if present are able to settle out and leave a melt layer. Lava near the flow front has cooled and has abundant small crystals.

    • With the heavier little more mafic minerals gone.. sunken the Sio2 in the remaing fluid coud perhaps be little higher than 49% as some Mauna Loa lavas are, Bowens reaction series tells everything. At 1156 C you have removed the olivine in fluid form from the mix and some pyroxenes. The crystal free nature explains the smooth nature.

      • The erupting lava is not totally crystal free, there is some olivine and plagioclase as is typical, but it is at tiny percentages as is usually the case of Hawaiian lava. That is probably because the lava is the cumulation of 20 years of intrusions, not the continuous flow that Kilauea gets, or what Mauna Loa got in the 1850s and 60s when it also erupted hot lava in long eruptions. it would be interesting to know what the 1881 lava temperature was, that eruption was also slow and long lived but I am not aware the supply was actually particularly high in that time, and Kilauea was not sleepy then either. Maybe 1881 was a net drain, not at equilibrium as it appeared.

  12. I see a M5.4 ocuured a little bit north of Taupo near Maroa today. Although it’s very deep at around 156.5km depth so most likley unrelated.

  13. Minor point. I’m not an earthquake enthusiast but I live in Taupo. Horomatangi reef is near the east side of the lake not the west..

    • Not again…
      It is not a bug, it is a feature.
      The regular readers know that I have a tendency to do this.
      You are of course correct.

  14. Pele building a Baugur – Holuhraun now: the spatter rampart cone looks identical to that one.

    • It was not mapped before but did get shown on the older maps as an arrow.

  15. I suppose the one mitigating factor at Taupo is that it only has a ‘lake’ as water supply.

    Big lake, yes. Mega-maar, yes. Ocean-ingress, no…

    Still, BE NOT in NZ if Taupo blows…
    Tangential, Landslide Blog’s coverage of Ischia made it to Geology.com, and with it the comments’ link to ‘Volcano Cafe’ and the unsettling review of ‘Ischia in motion’…

    • Actually, as far as we know at least, for the really large eruptions it is more the magma composition and structural properties of the system, no real “need” to interact with a large amount of water. Think about the Yellowstone hotspot and the series of calderas connected to it. Sure, a caldera might fill with water after the fact. But I do not think it is a “consolation” to not have an ocean at Taupo.

      People have I think here sometimes used the Hatepe eruption as an example of a very violent event, and it surely involved phreatomagmatic phases. But it seems to have been a very complex event, surely not just “Water meets magma, Boom, over”. The famous 20+ km^3 deposited in very short time seem to have been plinian(?).

      Maybe those who have studied that system in details can comment, is there a good overview publication for that eruption? Where does the often quoted “30km^3 within minutes” actually come from?

      • I dont kniw where the 30 km3 in a minute comes from, to be honest I think that is too high, but the mechanism of getting it to do that is a real thing. Basically it is the piston collapse event that Bardarbunga did in 2014, except in this case the eruption has gone through the ring fault. If the whole fault ends up lubricated with magma then the top will fall in, and the magma will get forced out, and then decompress. This is how an ignimbrite forms, it is not a plinian eruption, it is more violent and way more powerful than a plinian eruption 🙂
        The only thing that might be more violent than an ignimbrite is a sector collapse exposing a magma chamber as at St Helens, but those are probably not able to reach large scales.

        I imagine an ignimbrite flowing over the landscape being a lot like this, not like a blast wave or base surge but like a gigantic structure failing under gravity and hovercrafting under its own degassing. It is a glowing landslide that has no friction…



        • What I remember is also “30km^3 in minutes”, not “one minute”.

          My point about that event having the characteristics of a plinian deposit is that as far as my reading of the literature goes, it does not seem very “wet”. May be wrong though, I have to read up on Taupo.

          Something like a cubic kilometer per minute seems very possible, no? Mt St. Helens surely is a special case, failure of a flank and then debris avalanche. But, do we know as of yet how long the main event for HTHH in January lasted? I still remember the incredibly sharp pressure wave, it can not have been very long. And it seems several, maybe a bit under 10, cubic kilometers of rock were displaced?

          • Explosions are immediate, so you can’t really define an eruption rate. At some height above the eruption, it is actually easier as the column of ash takes a while to waft past. For Hunga Tonga, perhaps 30 minutes, so you may guess 1km3 per 3 minutes. (The 1 km3 here is tephra, not DRE, so ‘rock’ is not the right word.) For Toba, the eruption rate was quite similar, but this lasted for 10 days. The similarity may not be an accident: air can only carry so much tephra before its gets too heavy.

          • I guess it is possible I just cant see it happening in the DRE, the lid has to fall in and the magma needs to be able to squeeze through the ring dike. Rhyolite magma if it is low in crystals is not as viscous as it is at the surface, especially if it has high water, but still nothing like a mafic lava. Hunga Tonga Hunga Ha’apai was basaltic andesite, and crystal poor, the magma was probably very fluid, so given a chance to erupt the entire chamber at once there is little resistance. Really, it is this very fluidity that caused the explosion, far from being a hinderance.

            It is true viscous magma will inhibit degassing, but this is only going to be important as a factor if the eruption rate is low enough that a fluid magma cant really explode, because in that situation only one of them even has the option at all… Massive eruptions present an opportunity to erupt even the most fluid magma too fast for it to degas, so it explodes too, and then it reverses entirely, as any given exit will be able to erupt a fluid magma faster than a viscous one. The collapse of Krafla began as rhyolite but a large part if the ignimbrite was tholeiitic basalt, calderas can even make that explode…

            Supervolcanoes are rhyolite because that is easiest to accumulate into sufficient volume but perhaps is not maximizing the potential. I dont doubt the power of Taupoan eruptions, the ignimbrite sheet maps speak a thousand words, but perhaps it would not be quite so much of a detonation as we saw at HTHH.

          • This is a great article that looks into the Tonga eruption:


            “Regional infrasound, barometer, and volcanic plume observations suggest a complex eruption sequence occurring between 04:00 and ~04:30,
            not just a single onset or explosion.”

            The most intense portion of the Hunga Tonga eruption lasted about 30 minutes, as recorded by infrasound closest to the volcano. It was a sustained, continuous eruption, not an explosion. The positive pressure variation that circled the planet had a similar duration as this phase, although the mechanisms generating the wave are not clear, it looks like the entire 30 minute climax contributed to it, and it is classified as a Lamb wave. The audible booms are not the same thing as the Lamb wave. There were many different types of waves generated by the eruption, the big Lamb wave, gravity waves, infrasound, acoustic waves, seismic waves, and tsunamis, so it is an extremely complex event.

          • The figure 4C near the end of the article, which shows the IS-1 infrasound station data, shows best the structure of the eruption, the eruption starts slower and rapidly builds up in strength, reaching peak eruption rates in what I’m guessing is 10-20 minutes after the start of vigorous eruption. The first 30 minutes of eruption being the most intense. Then eruption the eruption continues at slowly decreasing eruption rates for another hour or so. There was a last brief spurt four hours later at ~08:31 UTC.

          • I agree that water is not so important when it comes to these eruptions. The main factor is having a large shallow magma chamber. Even calderas in dry areas produce extremely violent eruptions, the volcanoes of the Tibesti Mountains in the Sahara, for example, have similar massive caldera-forming ignimbrite deposits. The pyroclastic density current deposits of Yirrige caldera in the Tibest, for example, which is in one of the driest locations in the world, cover almost entirely a radius of 30 km around the volcano, with some branches reaching to 40 km if not more. An eruption of probably similar violence to Krakatau, given the PDC eruption deposits of both eruptions are very similar in extent. So I don’t see any need for water to be involved, it’s a matter of whether a large shallow magma chamber is present or not.

          • Albert,

            “For Hunga Tonga, perhaps 30 minutes, so you may guess 1km3 per 3 minutes. (The 1 km3 here is tephra, not DRE, so ‘rock’ is not the right word.) For Toba, the eruption rate was quite similar, but this lasted for 10 days. ”

            OK. So, say 30 minutes for Tonga. It is clear that the audible boom is not identical with the lamb wave. But it must have been a rapid event as far as volcanic eruptions go. 30 minutes will easily do until maybe more data are there, and the order of magnitude seems very plausible.

            Now, if the 9.5km^3 are really Tephra, I am not so much in the clear, as these seem to come from bathymetry of the *missing* stuff, not the bulk *deposits* (those to my knowledge have not yet been measured).

            See e.g. the graphic (ok, hardly a direct scientific publication, but anyhow) made by NIWA here:


            If the link does not get through, I describe, they give 5.5km^3 for Pinatubo 1991, which is in really good agreement with Self and others for the DRE, and 530km^3 for Oruanui, again in good agreement with DRE estimates. And 9.5km^3 for HTHH 2022.

            Be it as it may, I am very much able to believe that there is some sort of upper limit, at least until one could make the eruption zone much larger (which in turn is actually the case for the YTT origin, no?).

          • Hector:


            is I think very interesting in that context! I just found that Fig. 8 in the extended material contains surface pressure measurements from 64km distance. WOW!

            They register at least 4 distinct events, but the first one at 04:36 seems by far dominant. 30 minutes is probably already on the upper end for the duration of that event, but as said, will surely do for oom.

            The authors estimate the equivalent energy release to be a few gigatons TNT. Probably a bit larger than Pinatubo 1991 (which however took hours), possibly comparable to Krakatoa 1883.

            May indeed have been the most intense volcanic event anyone of us will get to see.

          • Yes, it was earth shattering. The hole is has left seems smaller than would be expected from a Krakatoa. The crater is now stated to be 700 meters deep, so lost about 500 meters. The outer slopes are undamaged, so the explosion remained in the original crater. That is where the argument about the size comes from: the hole says high VEI 5, the energy says much bigger. That may be due to the explosion taking place in shallow water, with very efficient energy transfer to the atmosphere, similar to a nuclear explosion. The explosion injected an extraordinary amount of water in the stratosphere (perhaps causing the peculiar weather this year) but little ash or SO2. This is a case where ‘VEI’ should really measure the explosive energy and not the amount of pulverized rock. We need a new Hunga Tonga scale.

          • Albert, I agree, VEI is a thing that tends to generate more discussions about the scale itself than the events it is supposed to measure. From the introduction of Newhall & Self 1982, they seem to itend it to be an equivalent to the earthquake magnitudes, which are a measure of energy in the end.
            Problem is the indicators of course.
            To quote the authors “…a semiquantitative compromise between poor data and the need in various disciplines to evaluate the record of past volcanism.”

            Table 1 in Newhall & Self 1982 has as you of course know a list of several criteria, including column height and duration (higher VEI echelons were thought to be >12hrs, somewhat curious also given the year of publication).
            But top ranked, of course volume of ejected material. They seem to distinguish from Tsuya 1955, so we can surely assume they mean pyroclastic ejecta.

            But what does the world today really use for the VEI? DRE or tephra volume? Honestly this seems not really been done consistently. As said, just take a look at the graphic in


            (If that link is filtered out, the NIWA site I linked above).

            2.5km^3 for Mt. St. Helens 1980, to me that seems to be tephra and maybe even include the material of the mountain flank.

            4km^3 for Vesuvius 79AD, seems to be tephra.

            5.5km^3 for Pinatubo 1991, clearly seems to be the often cited DRE volume(!).

            530km^3 for Oruanui, seems to be DRE, else it would not have been a VEI8.

            So, what is their “9.5km^3” for HTHH 2022, really? I am not sure!

            What I remember is that Shane Cronin earlier already seems to have spoken about 6.5km^3 of “rock” having been evacuated from the crater, so again this sounds rather like DRE:


            (Link to a comment at nature.com)

            The blast seems not to have destroyed the mountain. Maybe a strongly vertical nature of the blast helped to achieve the spectacular plume formation and waves? Moving mountain slopes takes a lot of energy out of the budget…

          • Typically, tephra volume is around 2.2 times the rock volume – it is obtained from measuring the density of the ejected material. The scale assumes that the energy goes into pulverizing the rock. As you noted, the original scale used quite a few parameters, but nowadays only ejected volume (pulverized) is used – it is the volume of the ignimbrite/ash. DRE is measured from the size of the crater, which has the advantage that you don’t need to measure ash thickness over large areas – just measure the crater. For an eruption in shallow water where much of the energy is transmitted over longer distance as a water shock wave and is used in part to vaporize water, neither measurement works well. They produce lower numbers than the other aspects of the VEI scale might do. It shows that the VEI scale is numerical but not quantitative.

          • Yes, in terms of measuring this as simply the energy and the brutal explosive power, then few eruptions can top what HTHH did. That eruption was beyond even the violence that was given to define an ultraplinian eruption, only Krakatau even comes close historically, Tambora was gigantic but not this instantaneously powerful.

            Certainly, this eruption was a far bigger bang than any of the 20th century eruptions, even if the volume is not first place the power was.

          • Albert, yes, that was also my understanding.

            Presumably then, Cronin’s 6.5km^3 at least would be rather DRE than tephra(?) As far as I know, the caldera is roughly 4km at widest, and was deepened by about 650 or 700m. Not incompatible with those numbers. Now if they found additional material displaced, this could increase the number.

            In any case, agreed of course, VEI by ejecta volume is not even a decisive measure of energy if there is agreement about the volume. HTHH had to disrupt, vaporizse, and displace a lot of water. Atmospheric and tsunami waves also carry away energy.

            As far as explosivity goes, it seems clear that atmospheric explosions of that magnitude happen quite rarely. The barometric disturbance would have easily been found decades, or even centuries, earlier.

            In the end, under a given (total, thermal) energy budget, one can throw less material fast, or more material slower.

          • I don’t know about Tambora being less intense than Hunga Tonga. The one report from near the volcano that narrates the eruption (from Sangar, ~40 km away from the volcano) seems to put the climatic phase of the eruption as ~4 hours long. And the ignimbrite seems to have affected Sangar for only 1 hour, where it blew away houses and uprooted trees. It had a very brief powerful main eruption.

          • Hector, at least as far as atmospheric waves (which are of course not an all encompassing measure of intensity, but more or less an inevitable consequence of large explosions) go, should that not even be “testable”?

            Some barometer stations existed in 1815. Same as there are records from Krakatoa 1883, if there are records from the days of the Tambora eruption, one could check for long-range or even worldwide barometric disturbances? Has maybe even been done already?

            This was my point here: for sure there have been much larger eruptions than HTHH in historic times. Maybe it did not reach VEI6 standards by ejecta volume, I simply do not know. But the intensity was of perhaps historic dimension!

    • Only a lake. Maybe underground connection to seawater though. Very plastic description, also by witnesses:

      Comparable? I’d say yes. Subduction plus Macolod Corridor, complex setting. VEI not even that important, main danger pyroclactic surge, ideally combined with a typhoon afterwards.

      To VC: A description like that is much more impressive and imaginable than rows and rows of numbers and numbers.

      Concerning the number Tallis has it in this article, but without a source. Tallis might be helpful though:
      – The most violent of which, the Hatepe eruption, hasn’t gotten as much attention as it’s peers. In my opinion, this might be the only historical eruption that rivals the 1883 eruption of Krakatoa’s intensity..This eruption released over 30 km3 of tephra in just 5 minutes and produced the most impressive pyroclastic flows since the Akahoya eruption.

      So, in case somebody addresses Tallis who loves it when somebody remembers his pieces he might find out the source.

      And this is about Taal’s hydrothermal reservoir, so not by Carl, but by Tallis instead:

      There’s more to volcanism in the Pacific Ocean than just VEI.

    • I saw that. I guess they’re sure there will be no new downrift outbreaks going forward.

      Now the camera is in position to catch a channel blockage, I suppose.

        • No this is the existing flow, it was goign past the hill behind the camera. Now that HVO has an inSAR and it shows the dike hasnt gone further, along with the vents dying off outside of #3, they turned the webcam around to look at the channel.

          Not as big or turbulent as the 2018 channel but that is a proper river of lava there, and very fast if you have seen the new videos HVO put out 🙂

  16. Edit for Admins: Accidentally posted under my full name. Not a big deal, but could admins please delete the duplicate with my full name? Thank you guys, and apologies.

    I just realized that the Oruanui eruption occurred right at the LGM (Last Glacial Maximum), to the extent that according to this paper, its ash can be used as a marker horizon for it:


    Is this entirely coincidental? Or did Oruanui instigate the last and harshest pulse of cold due to its enormous ash and sulfur emissions? Of course it was already heading toward the LGM well before Oruanui, but I’m wondering if the eruption corresponded to the coldest actual peak of the time period.

    Hard to find charts with a helpful resolution for this sort of thing, but:


    Of course volcanic cooling lasts a geologic nanosecond, so I’m aware that the LGM would probably be in about the same place with or without the eruption. Still, it’s fascinating. And I’m wondering if there was a ten year or so period in there that represents the apex of the previous cold state of our climate.

    • I think one has to be careful about such coincidences; the glacial maxima in itself will have higher dust densities in the ice. It would be very hard, I presume, to disentagle those effects. Example: we have transparency measurements of the South Pole ice down to ~2.5km. There is a gigantic backscatter feature between 60 and 70 kiloyears before present, the MIS4. This is however in all probability not volcanic, but a *consequence* of a maximum in the 41 kiloyerar “period”. The LGM is exactly those 41 000 years later.

      Shocking fact: the youngest Toba eruption has to my knowledge never been found in those cores…

  17. Once again the fate of Taupo’s trout fails to raise any concern. At least, this oversight has calmed my current bout of offence deprivation, albeit only in the short term.

  18. Question for those who have the inclination for the maths and the data

    If Mauna Loa has been eruption for 700k years and emerged from the sea 400k years ago and the oldest known rock are 200k years old (numbers from Afar TV) then to build to the size ML is now, how much lava has to erupt each year on average?

    I guess the rate would have been higher at first and the annual average is on a decaying curve as ML moves away from the hotspot, but it would be interesting to equate the annual average to recent eruption.

    • I do not know the answer to your exact question. However I do have estimated the volume of Hawaii in the past 3 million years. It turned out that the eruption rate has been approximately 0.1 km3/year, or 3.2 m3/s. I expect there is a small underestimate, because of some volume that sunk into the crust during the main activity of the volcanoes, but probably not too much. This rate is erupted mainly from Kilauea and Mauna Loa, but it probably switches from one volcano to the other.

      • Say 0.05 km3 Kilauea, and 0.05 km3 Mauna Loa, assuming and even partition of the supply between the two. Although I think Kilauea has probably been getting a larger share of the supply for some tens of thousands of years.

      • The official number is 0.21 km3/year from the plume, since the Big Island began to form. It was apparently a but lower before, and may have peaked at 400,000 years ago when Mauna Loa, Mauna Kea, Hualalai and Kohala were all in their shield stages. Although, none of them in that stage had quite the rate of growth Kilauea has shown since its shield stage began.

        It is really pretty hard to get individual volcano volumes though, they all merge. But the Island is estimated to be 213,000 km3.


        Given the oldest eruptions from the Big Island complex are about 1.2 million years old, that is a growth rate of 0.18 km3/year, maybe about 0.1 km3 for actual eruption rate long term average.

        • I think those articles may be overestimating the amount of subsidence under the Island of Hawaii, and particularly under Mauna Loa. And as such the overestimate the volumes. Some of the figures in that article show a 5-6 km subsidence of the crust under Mauna Loa, and I personally think that is way too much. I don’t have the data in front of me, but the decollement fault under Mauna Loa that is thought to represent the base of the volcanic pile, is no more than 2 km depressed under Mauna Loa, if memory serves me right. So while 0.1 km3 is an underestimate, 0.18 km3 is likely an overestimate. I personally think the actual number might close to 1.2 km3 which was the eruption rate of Pu’u’o’o.

          • There are some maps and crossections that show the decollement fault within the volcano. I imagine it forms at the boundary with the old crust but as the island gets heavier and depresses the crust more the fault gets a steeper gradient. At some point the fault may jump up a bit to keep the original gradient.

            Or, if the model of sills being the common mode of intrusions is correct, then there may be many huge thin sills at depth, potentially allowing for this vertical migration of the fault plane as well as the lubrication in absence of the sedimentary boundary. These might be made of weird magma that will never erupt and becomes highly evolved in all sorts of ways. There is a young alkaline basalt flow erupted into the moat at the base of the island pretty much exactly due west of Kapoho, it isnt a Puna Ridge vent, and it is believed to be only a couple centuries old at most. It is probably just mantle decompression melt escaping out a weak spot, but it is fun to speculat on the other options, maybe it is highly fractioned magma that leaked out if the deep rift through the fault. Perhaps it was during 1868, such a total slip of that whole fault may have some unexpected effects.

  19. Thanks everyone.

    If the annual volume is 0.21km3/yr as per Chad’s post, then how many years would an 1984 eruption be cover?

    I know it doesn’t work like this, but as a thought exercise, if it’s 38 years since the last eruption, this might suggest 7.98km3 accumulated ready to erupt. Does this indicate the potential available? If the volume is total ML and Kilauea, how much has been released via Kilauea and is left for ML?

  20. I see some pyrocumulus forming over the hot lava surfaces, just like during Leilani and Holuhraun. I can just imagine CAMP and Siberian Traps and how that impacted the convective weather ( lava supercells ) hot lava flows truely makes their own weather

    • Very nice 🙂

      Looks like I did overeatimate the flows southwest of Mokuaweoweo a bit, easy to happen when based on google earth. But these flows also look a lot more extensive than in most of the previous summit eruptions that happened in this area, I will add this to my map when I have time.

  21. The M5.6 caused a minor tsunami in the lake that killed two slightly innocent pedalboats, no pedalboat is ever completely innocent.

    It’s fun that an event roughly as energetic as the 1945 Hiroshima bomb might only sink a couple of pedalboats.

    Once Lawrence Livermore Lab did a pilot test of nuclear rubblization of an ore deposit. They amassed 4000 tons of TNT in a hole and lit the fuse…it caused a R4.5 tremor in the nearby town several miles away. I used to have their conference paper on the experiment (if you can call exploding 4000 tons of TNT “an experiment”) but I’ve mislaid it.

    I don’t know what the exact displacement was re the R5.6 tremor, nor does Geonet in their advisory report, but that’s actually quite a big earth-shattering kaboom.

  22. Geodetic data from the instrument on Horomatangi Reef:

    Latest dots on the chart might be anomalies that get smoothed out.
    You can see the inflation quite clearly for the last 6 months.
    Gaps in the chart I think because the instrument is in a tricky location in / under the lake.

    • Sorry replying to myself:
      This in relation to the Geonet’s advisory report from two days ago, where they said:

      The M5.6 earthquake caused ground movement measured at sensitive GNSS positioning instruments around Lake Taupō. At least 100 mm of horizontal movement was observed at an instrument at Horomatangi Reef. Further analysis of this data set is underway.

      Those charts are now showing that as well as horizontal displacement maybe 150mm South and 150mm East, there may have been 150mm or so uplift as well.
      But that’s only from 3 data points displayed now

      • One of the nice things USGS does with their earthquake reports is say what they mean. So they might give a point on a map for a R7.0 but then will add that typically Richter 7 earthquakes are due to a slippage of 20 km x 60 km, or somesuch area.

        Consequently this R5.6 is not just the Reef, but wider than that geographically. Which begs the question exactly what orientation and length of the slip was, and how it relates to the magma chamber.

        • Yes.
          There’s geodetic data from stations all around Taupo caldera presented in a user friendly way as charts like I posted, or raw data if you know how to interpret it.
          Geodetic data from all sites are on a clickable map here:
          Anyway there’s not a lot to see from other sites around the lake, just nornal tectonic movement, and in somke places a little deflation, and in other’s a little inflation, but a few mm. If the displacement from the instrument on the reef is real, then displacement didn’t happen (much) elsewhere.
          I wish there was more information even on this. I’m guessing that there are 3 new data points plotted as the new dots on that chart. But they way they appear (not just this event but quakes) then I guess the continuous GPS signal has jitter, that’s averaged for a daily displacement plotted on the chart So we now see three dots, two at about the same position, one about half way. I think the one at half way was the average for the day of the M5-6 Taupo quake, Makes me think the two consistent dots are showing what happened to the reef area, but maybe it was sitting on a smaller sbam that got bumped.
          So as another example. the Kaikoura GPS for the M7.8 quake in 2016.

          One dot in between the pre and post quake positions – not an actual single sample taken in the middle of a quake that lasted about 90 seconds as the main shock,

    • It is not under the lake, it is on a platform in the lake that is mounted on the reef. It could be called ground-0

  23. Mauna Loa is the star of the show but this is way more quakes than I have seen at Kilauea in a long time.

    The quakes clustered under Kilauea Iki are all from the past 2 days too by comparison to the live USGS map. The recently observed apparent deflation and flank slip hypothesized by me and Hector before seems to have stopped, as has the contraction on the ERZ again, so this could plausibly represent pressure quakes. Maybe soon we will get a more spectacular double eruption 🙂

    • The cluster of earthquakes SE of Kilauea Iki is interesting. I have been looking back at a cluster of earthquakes in that very same location on August 11 2021. There was a flurry of Kilauea Iki earthquakes simultaneous with a flurry of earthquakes in the uppermost SWRZ connector, as well as 2 earthquakes in Keanakakoi, and 2 earthquakes in the Namakanipaio fault zone. So it was very similar to what we have now.

      I think that what is causing these earthquakes is a magma driven slip centred in Halema’uma’u which is activating an area of faults from Namakanipaio to Kilauea Iki. The very rapid southward movement south of the caldera still continues, fastest near Keanakakoi, where CRIM station is located, but reaches all the way to Hilina Pali, at least. However the uplift is not very strong, and the summit lava lake is slowly draining, even though it responds to the DI events. My guess is that magma is draining from the shallow system, and building up deep under the caldera, pushing the flank southward.

    • It does look like earthquakes SE of Kilauea Iki have been more intense, and probably gradually increasing, since August. The Namakanipaio area has been unusually active in the past month. The south caldera area, including the SWRZ connector, and the ERZ connector from Keanakakoi to Puhimau, show the same very clear pattern of gradually increasing seismicity during the later half of this year.

      But the ERZ conduit beyond Puhimau has been dead quiet. And the ERZ conduit connector always seems to flare with quakes down to Mauna Ulu every time there is going to be an eruption or intrusion

      • If the SWRZ connector or Kilauea Iki are showing quakes though, would it not be possible for a local eruption at one of these places to occur? Kilauea Iki is complicated but seems at least possibly to have its own system, it is sort if lime its iwn volcano, quite literally a little Kilauea. 1959 magma was way too hot and primitive to come from the main magma chamber, although the small eruptions in the 19th century probably did.

        It is just to keep all the possibilities open, there were all of those SWRZ eruptions between 1790 and 1823, without an ERZ eruption or intrusion inbetween those years, perhaps the conduits are not equivalent and can behave independant.

        • Coincidentally, I was reading some papers on Kilauea magma mixing, differentiation, olivine control–gripping stuff.

          Back in the 60s-70s, Kilauea would erupt magma from the ERZ that hadn’t been erupted at Halemaumau yet, leading to the curiosity of ‘1968’ magma being erupted in 1961.

          One thing I saw–and I had to look twice–was that the 1954 Halemaumau eruption contained ‘1959’ magma! I always was under the assumption that the Iki lava took the express route from the mantle–do not pass go, do not collect $200, but bring your olivine with you to the surface!

          Apparently not, unless later research clarified things. And toward the end of 1960 Kapoho, a small amount, relatively of 1959 magma was erupted.

  24. Delurking after learning a tremendous amount from the posts here over the past few months, because I haven’t seen mention of this one yet – the week has claimed yet another mountain! This one just as the monsoon arives, and with rather more ashfall (and fewer webcams) than Mauna Loa:

    Hoping the casualty count stays as low as has been reported so far, but that much ash and rain combined can’t be great

      • But, how does he know that? I tried to find where he was getting that information but not there. Could be pure coincidence or he got the information from somewhere else entirely that we don’t know of.

        • I don’t know how he knew that Semeru was inflating, I couldn’t find any information either. His videos are great but he should have cited where he got the data from.

    • I’m wondering if this footage is legit. Unless it is filmed such that the summit is behind a hill it would not make sense, as I presume the eruption would have resulted from a lava dome collapse at the summit?

      • Seems real footage to me. The summit is to the left shrouded in clouds, the video points to the flank of the mountains, the pyroclastic flows moves over the ground then “erupts” upwards into a coignimbrite cloud.

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