Ten volcanoes with super-eruption potential: Part I

Where will the next VEI 8 supereruption (>1000 km3 of erupted volume) of the planet take place? This is the question that these articles are here to answer. To put it another way, this list will evaluate and rank the supereruption potential of several volcanic systems. I didn’t use any objective parameter to calculate which had the greatest probability, the way I ranked them is just my personal opinion regarding how likely or how soon a supereruption could happen in each of them. The order of the volcanoes was in fact changed a few times while making it as I learned more details about them.

All 10 volcanoes featured here show some potential to do a VEI-8 eruption in a GEOLOGIC FUTURE. So first of all and to clear out this important aspect, we are not going to see a supereruption in our lifetimes, thankfully. Perhaps there is a really really really slim chance that one could take place, but due to the very low frequency of these events and because no volcano is showing any signs of being about to immediately throw one of them, I dare say we won’t see it nor will countless future generations to come. Phew… Though I imagine some people being rather disappointed right now.

Also, if you have not read the article Batholiths and Flare-ups, it would be better if you read that first, since it is meant to be an introduction.

The factors used to gauge the supereruption potential should be explained first. One is that the volcano must have dacite or rhyolite (or their subvariants), which are the kind of magmas that make up supereruptions. Someone may come up with an example of a supereruption that had a basaltic or other unusual composition dating back to the Jurassic Period. However these are very rare exceptions under extremely rare situations, like flood basalts.

Another factor is that the amount of eruptible dacite or rhyolite must be very large, ~450 km3 or more. Eruptible means that it is assembled into a single melt-rich body (magma chamber), that will exist within a larger mush system (a batholith) that is not eruptible. Magma chambers usually look like lenses or sills, very spread out, that is why a system that produces a supereruption must be extensive, I considered the ~420 km2 area of Taupo to be the minimum requirement. Ring fissure eruptions can be taken as a factor for the existence of a mature magma body/chamber.

You could be wondering if I am going to take seismic tomography into account here. Problem is that while tomography seems able to very roughly detect the bigger mush bodies it seems to fail or be very bad at locating melt-rich bodies (the magma chambers).

Another way to know roughly how large is amount of melt assembled, is to look at the size of regular eruptions. Although the caldera-forming eruptions are the ones that get most of the attention, the vast majority of eruptions will be much smaller and not involve collapse. Effusive eruptions are very telling since these can only evacuate a very small fraction of a melt body. This is because if magmastatic pressure falls below the point where magma can’t be raised to the surface anymore, then the eruption stops, it lacks the lift from outgassing that explosive eruptions enjoy. At shield volcanoes and stratovolcanoes flank eruptions can release significant pressure since they erupt at low elevations that can reduce much more the magmastatic pressure, but this is not the case for large calderas which are usually at the same level as the surrounding terrain. This is why caldera systems that produce effusive eruptions of more than 2 km3 are extremely rare to find. Lava flows or domes bigger than this indicate extraordinary amounts of assembled melt.

I have also considered how large is the heat flux into the volcano. If new heat no longer enters the system then regardless of how big it is, it should gradually freeze into rock, like your closest granitic mountain landscape. Whether mantle and crustal melting continue below a system is a fundamental question. The heat released by a geothermal field, through geysers and hot springs can also be indicative of a large heat flow.

So taking into account these factors here comes the ranking from least likely to most likely to produce a supereruption. Let’s go!

 

10. Incapillo (Argentina)

Lonely and barely known Incapillo volcano will at least get a place. With so many calderas in the Central Andes it is quite easy to miss some of them. Like the other big volcanoes of the region, Incapillo was formed due to rollback of the Puna slab, but it lies further south than all the others, far away from the APVC. It’s half standing in the volcanic graveyard of the Pampean flat slab and half in the tumultuous flare-up of the Puna slab. At the very veil I find impossible to guess whether this system will get future supply or not, it is all or nothing.

Incapillo. Thanks to Bruno Aiub Robledo

While it is a small unremarkable 5×6 km caldera, it is surrounded by a much more extensive volcanic field of dacitic and rhyodacitic lava domes large enough to host a VEI-8. A large silicic magma body seems to have attempted to develop but it still needed some assembling to do. However it looks like activity has stopped completely. All the domes seem old and to predate the caldera which is 510,000 years old. Now Incapillo stands in a deep volcanic silence.

At some point in the future, the Pampean Slab is likely to do rollback which will certainly restore a large influx to Incapillo and perhaps lead to a supereruption, but that is in the long-term, very far away.

 

9. Toba (Indonesia)

A giant among giants, probably the largest caldera in the Planet that can still be considered active. This Indonesian volcano has produced 2 supereruptions so big that make all others in this list look small. The first was 840,000 years ago and ejected 5,300 km3 (bulk), another small collapse took place at 500,000 years. The last collapse was the Younger Toba Tuff, 75,000 years ago, which produced 2,800-5,300 km3 of DRE. The whole area was engulfed by a 100×30 km sized caldera bounded by up to 2 kilometre high cliffs. Some estimates that include distal ash-fall put the eruption as a VEI-9. Could it be true, do VEI-9s really exist!? I don’t know, but whether this is right or not the YTT was undeniably huge!

What is the secret to such a gigantic caldera? What geologic mechanism could be behind it all? There is subduction going on underneath and also extension that is reflected in the formation of NE-SW basins oblique to the Great Sumatran Fault. This is a prominent strike-slip fault system that runs across Sumatra, volcanoes are at or near it. Toba is located 15 km to the northeast of the Great Sumatran Fault in what seems to be one of those NE-SW corridors of extension and above a possible slab tear has been proposed to lie at the melt source. However the combination of extension and subduction, and even slab tears, are quite common in the world, but there is nothing else like Toba out there. The explanation seems incomplete.

Geology of Sumatra

Toba has the typical internal plumbing of large caldera systems. It crowns an uplifted area of Sumatra that is 220 × 100 km across, linked to intrusions and crustal thickening. A deeper reservoir of basalt mush is located at 30-50 km depth and contains 50,000 km3. While shallower reservoirs contain intermediate and silicic magmas. The earliest volcanism was a 500 meter thick succession of andesites and basaltic-andesites around 1.3 Ma, suggesting that the formation of a layer of andesitic melts preceded the silicic volcanism and caldera activity.

The unmistakable look of Toba in digital topography. Note the broad doming around Toba, it’s a result of batholith formation at depth. Thanks to NASA.

What about the future of Toba? A few small post-collapse domes have erupted along margins of the caldera while Samosir Island is being uplifted by a resurgent dome. However this doesn’t really mean much, some calderas undergo resurgence only to later become extinct. Caldera cycles of Toba have lasted ~400,000 years, so it is unlikely that enough time has passed since the YTT eruption for Toba to be anywhere near recovering. Toba could do more caldera collapses in the future, but not yet, this giant is going to need a long time to build up melt.

 

8. Nevados Ojos del Salado and neighbours (Argentina-Chile)

Another familiar name? We are back to the Central Andes and the Puna Slab. The last 10 million years of flare-up in the region is a tale of 4 giant andesitic MASHs/mush bodies. The more famous and bigger Altiplano-Puna is well known but it has coexisted with Lazufre, Cerro Galan and Incahuasi, each has brought forth a couple of calderas.

From a mush-wide perspective Incahuasi remains the most active of the 4, it has the youngest ignimbrites among them. This was the Cerro Blanco eruption around 4,200 years ago which produced more than 170 km3. There are also extensive basaltic volcanic fields which show that melting of the mantle over a wide area is still going down below, something that seems largely over in the 3 other complexes.

The Incahuasi volcanic complex. Some calderas visible to the upper left and center. Thanks to NASA.

Nevados Ojos del Salado is part of the Incahuasi Complex and is also the highest volcano in the world at 6879 m. It is not much of a sight though, instead of an elegant conical stratovolcano what we find is a bunch of irregular domes and cones. Broad doming above the Incahuasi batholith helps this volcano grow so high even though the prominence above the surrounding ground is small (only 2 km higher).

The sight of Nevado Ojos del Salado, not the majestic symmetrical cone. Photograph thanks to sergejf.

The main reason it makes it into the ranking is a lava dome located on its west flank. It is called El Solo. It doesn’t have any volumes estimates that I could find so I made my own, the dome and pyroclastic flows from dome collapse together seem to be at least 15 km3 (bulk). According to GVP the eruption took place 1000-1500 years ago, although I couldn’t locate the original source.

There is a large body of molten rhyodacite that fed the El Solo eruption and there are also some sizable domes to the east. The region however shows mixed volcanism with andesite and basalt flows together with the more evolved domes. There is no sign that gives away the existence of a single broad melt film: was it just a transient chamber that fed El Solo and will now disappear? or is it the start of a new long-lived large caldera system? The Nevados Ojos del Salado group is 70×30 km which could host a VEI-8 caldera, but the system could fall short with a VEI-7 or not even collapse at all. It will take a long time but the supply is strong and secure so it provides a promising means to eventually achieve something interesting.

 

7. Tatio (Bolivia-Chile)

At first it might seem like a group of volcanoes unrelated to each other but there a signs of a large magma chamber hiding here. Its location is the Altiplano-Puna, a giant batholith that was properly presented in the introduction article and mentioned over and over again. When you have used the word giant in front of the word batholith it is because this no ordinary system. But despite its tremendous size the complex is well into decline.

The Altiplano-Puna is a result of the Puna slab steepening, starting around 12 Ma. Short pulses of ignimbrite activity took place at 8.4, 5.5, and 4.0 Ma that produced the largest eruptions of the complex. Volcanic activity has died off in most of the flare-up area and remains only in the active arc above the subducting plate, consisting of generic stratovolcanoes (a typical arc activity). Has the Altiplano-Puna burnt off all of the extra melting from the slab steepening? It does seem possible.

Then why am I putting an APVC volcano in this ranking? This is because Tatio might be the last remnant of major silicic activity in the region as well as maybe the last shot it will get at doing a supereruption.

The 40 km3 DRE Tatio Ignimbrite is the youngest major explosive event of the APVC. It happened 750,000 years ago. Its exact source is unclear, but it is located next to a hyperactive geyser field and 3 voluminous lava domes. The geyser field, known as El Tatio, is the 3rd largest in the Planet: it has been active for 27,000 years.

Tatio geysers in the foreground. Thick tongue of Cerro Chao dome visible behind, comes up between the two stratovolcanoes. Photograph thanks to Albert Backer.

Geysers require several conditions to be met. First is the abundance of water circulating through fractures. Second is silica rich rocks which provide the material (dissolved silica) that through its dissolution and precipitation create geyser conduits. And last, a strong source of heat to boil the water. This shows there is a large and active source of heat below, molten dacite in all likelihood.

Of the 3 massive domes the most remarkable is the dacitic Cerro Chao <100,000 years old and with an impressive volume of 26 km3, this is the size expected if it was fed from a supereruption-sized melt rich body. All the above-mentioned features coexist within an area of 50×20 km, which is the speculative Tatio Magma Body.

Chao and Chillahuita dacite domes. Chao is the big one. Thanks to NASA.

However these are the last steps of the great APVC: with the dwindling melt influx nothing guarantees this volcano won’t freeze to death without accomplishing anything truly remarkable. While the slowing supply is its weakness, its strength is that it is already very advanced in the melt assembly process, shown by Cerro Chao. Vast amounts of dacite have built up underneath these remote and barren landscapes much like it happened back when the flare-up was at its peak, will it be a failed attempt? or the successful rebirth of a former glory?

 

To be continued…

Research

About Toba:

https://www.nature.com/articles/ncomms12228

https://www.frontiersin.org/articles/10.3389/feart.2014.00016/full

History of the Altiplano-Puna Volcanic Complex:

https://pubs.geoscienceworld.org/geosphere/article-lookup/12/4/1054

151 thoughts on “Ten volcanoes with super-eruption potential: Part I

  1. First!!
    Just kidding.

    I read the news that police in new Zeeland are investigating people with regards to the white island eruption last year.
    One of the parties investigated is a private geological company that issues volcanic predictions!?

    Have the new Zeelanders completely outsourced volcanic and earthquake predictions to a private company?

    • Whakari/White Island is a legal anomaly. Most NZ volcanoes are in National Parks, but this one is private property, a consequence of the sulphur mining there around the early 20th Century. This might have something to do with it.

  2. Thanks for the articles you write Héctor. The one about Flare ups I enjoyed much.
    But here a point of criticism. Why speak of super-eruption in the title? The word super in relation to volcanism is often (as you mentioned in the Flare up article) misused and is feeding thrill seeking. Something that is avoided in VC carefully.
    VEI 8 does name it all right?

    • Supereruption is less misleading than supervolcano and as Jamie Farrell stated “there are no supervolcanoes, only volcanoes that have super eruptions”. That was in an article of the Yellowstone Caldera chronicles that I found interesting.

      But it’s true that it could become misused in the future and that VEI-8 would be a better term for it so that this can be avoided.

  3. Very interesting, would be quite a sight if one if these massive domes was to form now, an entire mountain just forming right before our eyes. I guess though if it is like Santiaguito then it might take a very long time, probably centuries.

    There was another swarm on Kilauea too, really looks like its on the final run now, maybe I actually have a good prediction for May 2021 eruption 🙂

    • Tiltmeter has just shot up on a near vertical following a larger mag 3+ quake, and from the top of a DI inflation too. This swarm has also lit up the east rift to Mauna Ulu too, definitely a magmatic event.

      • That is an impressive shift. It steepened towards the caldera. 10 microradians should be something like 2-3 cm deflation in the caldera, if i have done my estimation correctly. This may be tectonic rather than magmatic: the tilt can’t tell you that. But do be aware that one arm of this tilt meter stopped worked a few days ago so there may be a problem with it.

        • The tiltmeter on the main page is supposed to simply record inflation as up and deflation as down, the green line is Pu’u O’o

          • That is true if the source of the tilt change is indeed inflation/deflation, but a tilt meter can only measure changes in slope, so it’s impossible to say if one end went up or the other end went down. Tectonic changes may play tricks on a tilt meter, so you don’t want to rely on it as the only source to measure inflation/deflation.

          • Correct. Tilt is a change in slope – it is not a GPS. It does not tell where it goes up or down, or by how much unless you know the precise location. I gave a number assuming the change is in the centre of the caldera, but that is not where the earthquakes were.

        • The tiltmeter at Uwekahuna is picking outward tilting, inflation.

          There was an unusually strong inflation of the shallow system of Kilauea, yesterday following the last DI event, Uwekahuna picks around 2 microrads of inflationary tilt. There was also a swarm down the East Rift conduit to Napau Crater, this shows that the horizontal pipe feeding the ERZ was increasing in pressure and fracturing the overlying rock, this happens sometimes and is know as an inflationary swarm. Past 3:14 UTC this swarm dies off showing that the pressure is being relieved.

          At around this time an intrusion starts in the summit area, the first earthquake shown to belong to this sequence is at 3:47 UTC. It seems to have pushed outwards Uwekahuna and to have decreased pressure in the volcano so it’s probably a small sill or a dyke in the Halema’uma’u or south caldera rim areas. But I can’t tell exactly what happened. It is possibly related to the swarm on Monday and seems similar but on a larger scale to a swarm that happened on March 16. The GPS will give more information when they start updating.

          Here is a capture of the magnitude 3.1 earthquake. it was really complex and there are very long period waves:

          • Yes, I had the wrong orientation of the tilt. It is a strange effect though, an almost instant jump followed by a continuing change. It is almost like the rim of the crater is moving.

          • The sudden jump is probably the 2-hour-long sill or dyke intrusion visible in the seismometers. Other tiltmeters like SDH or SMC seem to have recorded the deflation of the volcano during that time interval, perhaps they were far from the intrusion.

            Tilting before and after the intrusion is strange, it seems to be inflation of the magma storage but it is surprisingly fast.

          • The total upward tilt is about 12 microradians and still going up right now, I think this is probably the last few months of deep inflation breaking through. If you take the low end supply rate of 0.1 km3/year then 3-4 months is about 30 million m3 of magma, and 60 million if it is supplied at 0.2 km3/year. Im inclined to go towards the higher end given the rift took off some pressure but a summit intrusion still happened.

            I dont know exactly how much magma volume has historically been correlated with such a change.

          • Earthquakes are happening in the east rift zone conduit again looks like the volume emptied by the intrusion must be nearly filled or filled again.

            HVO included some information on this event in its monthly release but it doesn’t go into the causes.

            https://www.usgs.gov/volcanoes/kilauea/volcano-updates

            They also don’t mention that Kilauea keeps inflating right now at extraordinary rates. As far as I know the fastest ever recorded by the Uwekahuna tiltmeter in the history of Kilauea.

            Right now Kilauea is swelling 12 times faster than even the fastest months of inflation in 2019, and it more than doubles the greatest long-term inflation recorded ever in Kilauea, that of latest 1960 to early 1961. If this rate holds it will be something unprecedented, though that remains to be seen. But if it continues then it must be the Pahala mantle surge, the response from the hotspot to the eruption of 2018…

          • https://www.youtube.com/watch?v=6oBGgO7SfTc

            This is a pretty good summary, but again as you say it doesnt include any of the inflation after the event and is rather dismissive of the pretty obvious inflation signal when looking at the GPS plots. Having watched these guys since 2018 though I wouldnt be surprised if the video was pre-recorded yesterday and at that time they thought the signal would level out and go on as if nothing changed, they also have to be a bit neutral on the matter I suppose, unlike here… 🙂

            As much as I would like to see an eruption, if it happens right now it probably wont be very big, unless it is a lake explosion which will be big in magnitude but probably not in volume. If it is in any longer than 6 months though at this rate we are looking at a major event, there is only so long the supply can be absorbed and its looking to be at that limit now.

  4. The VEI 8s happened a while back. Can we be sure they were single events? & not a series?

    The list from Wikipedia: Wah Wah Springs (30,000,000 BC), La Garita (26,300,000 BC), Ōdai Caldera (13,700,000 BC) Cerro Galán (2,200,000 BC), Huckleberry Ridge Tuff (2,100,000 BC), Yellowstone (630,000 BC), Whakamaru (in TVZ) (254,000 BC),[6] Toba (74,000 BC), Taupo (26,500 BC).

    • If you are familiar with the Yellowstone Caldera chronicles, there was a recent study that said the Huckleberry ridge eruption was probably several eruptions over the course of a century or so. Each would have been a VEI 7 and realy pretty much exactly as imagined only just that tiny bit smaller, but it was not 1 VEI 8, it would have been decades between them. This also does explain the massive extent and weird shape of the caldera it made, it is several calderas all merged. I do wonder if this is also the case for a lot of the others, that they were VEI 7s in close succession but which would have been separate eruptions.

      I suspect Hector was going to mention this in the next article… 🙂 Yellowstone is also known to produce very large volume rhyolite lava flows and has done so in the last 100,000 years, and has huge heat flow so chances are its still got some life though its not about to do anything soon. If it does erupt it will probably be another lava flow though given the size the vent clearing stage could still be an easy VEI 5, so not harmless but not apocalyptic.

      • I’ve read quite a long time ago one of those “super”-eruptions in New Zealand was actually likely several smaller eruptions (probably VEI-6/7) rather than one great big VEI-8. I think that was the 26kya Oruanui eruption from Taupo Caldera.

        La Garita, OTOH, sounds to me like it generated one great big VEI-8 due to the remarkable chemical uniformity of the dacitic Fish Canyon Tuff (~28 mya).

        • I hadn’t thought much about this but it does appear Oruanui had several pauses, weeks or months long. Most likely it would have been all part of one same collapse with cyclic activity due to the episodic collapse events, but would activity have stopped completely in between? Maybe there were weak steam explosions or waning ash plumes between the paroxysmal events. So the question of whether or not it was 1 eruption is something hard to know from the geologic record but caldera forming eruptions are often complex events with episodic activity.

    • Toba was a single eruption. At least its main event. WE know nothing about small precursors, of course. The duration of the eruption is believed to be 9 days, and it was a ring eruption. The centre of the caldera did not erupt, as far as we know. You can imagine it as 200-km long rift eruption on the edge of the caldera. It became so enormous because of the sheer length of the eruptive fissure.

      An important question is how such a massive magma chamber can be kept in storage. You need a very strong roof of the magma chamber. Imaging a 50-km wide span of a dome! That collapses under its own weight. The magma has to be quite deep, 10 km or more. And the magma can’t be too hot or it will melt through before enough magma has accumulated.

    • Awassa – 1, 270,000 BC – still highly active.
      O’a/Shala was likely a high end VEI7 (500 km3 plus).

      Are the TVZ calderas chronologically ordered north to south?
      If so then the area between Tongariro & Taupo could be the next.
      Hatepe (VEI7) was violent, and was only 180 AD.

  5. …do VEI-9s really exist!?

    Technically, no. But if you follow the logical expansion of the upper end of the scale as being a 10x increase over the previous levels… a VEI-9 would be in excess of 10,000 km³

    Note for all, at the low end of the scale, this rule of thumb doesn’t apply. there is a discontinuity in the jump from VEI 1 to VEI 2.


    Elsewhere, in a discussion among VC admins, the topic of some things in Spain came up and mention was made of a little known faultline. It was mentioned that the fault was capable of throwing a Mag 7.0 quake. That took me a little aback. I remembered that Wells-Coppersmith had done a fairly decent amount of work in this field. (“New Empirical Relationships among Magnitude, Rupture Length, Rupture Width, Rupture Area, and Surface Displacement“) so I took their formula and generated a reference plot. This is the subsurface rupture length vs quake magnitude for a strike-slip fault line.

    I would do one of these for reverse mode faulting but they specifically state that the data is not valid at the 95% level. Assumedly this one is. Remember, it is specifically for strike-slip faulting.

    You “full margin rip” people need to remember that. This does NOT apply to the Cascadia Subduction zone. Though just from eyeballing the plot it is pretty evident that a Mag 9.0 there is probably not going to be very good at all, even if the plot is invalid for that geology.

    • With this in mind – are there many/any places on earth with a long enough series of faults that could rupture and create a mag 9.6+?

    • When you concider the possibility of subparallel faults getting involved and participating in the failure… it gets more possible.

      A 9.6 works out to about 2409 km subsurface rupture length and an average of 208 meters displacement…. at 37 m/s+ acceleration within 20 km of the epicenter. That’s MMI X out to around 260 km of the focal point.

      • Usually there will be a segment that gets stuck and doesn’t rupture though right?
        So if we look at all subduction zones what we want to be looking for is fault length, whether or not the faults are parallel/aligned, and whether or not there is flat slab subduction?

        I found this study: https://www.frontiersin.org/articles/10.3389/feart.2019.00136/full
        It implies that the maximum earthquake possible is an M9.8 in Chile – which would be just unimaginable.

      • Well, that’s the thing. If you have watched any of the Cascadia videos by CWU you’ll know that the “lock zone” on the SZ is somewhat below the accretionary prism, below that is a more malleable region that is responsible for the slow-slip events (silent quakes). Every few months the GPS motion stops and reverses direction during the slow-slip events. It is hypothesized that this incrementally loads the locked section and that eventually, may be the precursor signal to a failure in the locked region.

        Due to the crust flexure on the over riding portion of the fault, it is difficult to get a good fit of the data for reverse mode faulting. Wells-Coppersmith ran into this when constructing their formulas.

        It’s not like a wrench fault where the geometry of the fault trace presents a clearly locked section like on the San Andreas. (responsible for the Salton Sink)

        Reference that warning, that means that this plot can be very inaccurate. Think of it as a “ball park” estimate.

        • I imagine the Salton Sea to be a bit like in Iceland where there’s a block in-between and the fault kind of zigzags, or presents itself in multiple non-connected parallels instead.

          Is the Cascadia lock zone due to a change in the subduction angle or due to the greater/lesser subduction speed in another area of the fault?

          It is 1000km but there is a bend and ‘catch points’ so it must be able to accumulate a massive amount of strain before unleashing anything M9+

        • Despite those “zig-zags,” the principle motion is not horizontal along the surface trace of the fault. It is one side diving beneath the other. The “locked” region of concern is along the interface surface where the two plates “mesh” as one dives under the other. This tends to manifest as oceanic sediment and island arcs get scraped off and become the accretion prism and/or non-native teranes plastered (sutured) onto the north American craton.

          The big spooky bit about subduction zones such as this, is that the over-riding plate tends to “bow up” like a carpet pushed too hard against a wall. This stores extra energy like a spring that is released when the fault interface fails. This particular geometry is often referred to as a “megathrust” fault. This is the “…accumulate a massive amount of strain…” part of the megathrust system. The coast of Japan lurched eastward by several feet when the Tōhoku quake hit. (2.4 m)

          The Sumatra–Andaman earthquake (2004) and the Tōhoku earthquake (2011) are good examples of megathrust faults and what they can produce. According to WikiPeekAtYa “Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes.” Japan’s “Orphan Tsunami” of 1700 is evaluated to have originated from a Mag 9.0 (or so) quake along the US Pacific Northwest 26 January 1700. Contrary to popular belief, Seattle will likely not be hit by a tsunami if and when it ruptures again. By the time the wave works it’s way down the Juan de Fuca Channel much of the power will have been dissipated. Coastal cities, well, that’s a different story. Not a good place to be. Everybody is going to be in for a wild ride from the quake, but Seattle most likely will not be inundated. Portions of it may have a lahar problem if the altered rock on top of Mount Rainer are mobilized from the shaking. Some of those outlying neighborhoods are built on old lahar deposits.

          In general, if you live in a Lahar hazard zone, take the initiative and seek higher ground if everything goes to hell in a hand-basket. Those lahar warning systems may only give you a short time to flee when they go off. DON’T BE COMPLACENT. ALWAYS KNOW WHICH WAY IS SAFE TO FLEE. You aren’t going to have time to think about which way to go.
          Better yet, “Don’t be there” is my trite canned saying… but applicable if you are risk averse. When is it going to happen? No one knows for sure. But geologists are constantly working on that question. From their research, it is known that the entire fault doesn’t always fail at the same time. Some segments fail by themselves as evidenced by turbidite deposits in various submarine canyons.

          The only thing you can say with near certainty about the Cascadia SZ is that it will fail… eventually.

          Personally, I don’t live there. But I deal with a hurricane threat every year. At least I can see them coming.

          Nick Zentner of CWU gives a FANTASTIC lecture about this area.

          Note: On his chalkboard is a list of Mag 6.5 or greater earthquakes on the San Andreas fault in California. The recurrence interval of that data is 6 years 3 months to 14 years 1 month at the 95% confidence interval. 10 years 2 months on average.

          • The bulging before an M9 is large enough to affect the rotation of the earth. There is a notable (but very small) change in the length of the day after the quake.

  6. https://news.agu.org/press-release/cluster-of-alaskan-islands-could-be-single-interconnected-giant-volcano/

    Quite an interesting news item to come up. I suspect there are likely more of these around the world we will never know about due to being too old, or hidden beneath the ocean surface, making it near impossible to map or document the caldera boundary.

    As I’ve long pointed out, the Aleutians are possibly the most prolific arc-based system of VEI-6+ volcanic eruptions relative to the total amount of volcanoes in the arc (for a large arc that is). Not surprised there may be a really big bugger hidden within the other calderas that are already quite large there.

    • I did just see this on the USGS volcanoes facebook, they also released a statement on the activity at Kilauea so whoever manages that page has been pretty busy

      It does seem quite plausible for there to be big calderas with younger cones in the Aleutian islands, that sort of system is found in most other places including the continental part of the arc. There was a comment on the facebook post about it being maybe similar to Soputan and Tonando caldera, so chance of an eruption of any large scale is very small but interesting read.

  7. I don’t think Hector will pick this for his list, but if I had to make a personal pick for the #1 most likely to be the next supervolcanic eruption, it would be this guy:

    https://imgur.com/YdwIkH4

    It checks off a lot of the boxes in my opinion.

    • Yikes. About that ring-like structure…is it generally considered that this cluster of volcanoes is one volcano, or is that your hypothesis?

      • The ring-like structure is just the local graben structure. This is part of the spreading zone it sits within, but likely wouldn’t be related to a potential future caldera itself.

        As for considering this as one volcano, that depends on how you define it. Most of the papers I’ve read believe it has one central deep heat source, but that heat source branches out and splits around 15-30km deep in the crust. I would call this separate volcanoes with a common deep heat source. Think of it as you would a somma volcano system, where you often get multiple volcanoes popping up around a ring-fault type structure with a singular deep heat source.

    • Its still mostly mafic, Bezymianny has gone from dacite to basaltic andesite today, and Kluychevskoy and Tolbachik are basalt, it hasnt melted the crust yet to make large volumes of silicic magma yet. It is probably going to do that in time but maybe not a good pick for the next VEI 8 when theres mature silicic systems that are probably set to go now, maybe a couple spaces down the list in the future.

      I guess there is just a very tiny possibility right now for a flood basalt though, sort of a basaltic effusive VEI 6+, but probably not.

      • And their calderas like those of Ushovsky or Tolbachik form in voluminous lateral mafic eruptions, not explosive events (unless they blow laterally, but that is not really a chamber collapse). They do not seem to be the large caldera kind to me, at least not yet, maybe in the long long term.

        • I guess that means Klyuchevskoy is a real candidate for a flood basalt in the future, as well as sector collapse. Its sort of like Etna but a lot younger. Probably there isnt much of a magma chamber yet though

          • Large highly feed subduction volcanoes like Ambrym,Etna and Masaya that haves a very high influx, ( Specialy Masaya ) can grow basalt chambers with well over 10 km3 inside, so they can perhaps do a Laki in an extreme chase. Ambrym and Masaya is subduction zone volcanoes with very large influxes, they can produce something like Laki perhaps in extreme chases. Masaya is becomming a scary volcano for managua

            But the really big LIPs ( 6 million km3 ) in 300 thousand years are indeed products of large rising mantle plumes thats decompressed.
            When a Superplume head decompresses you gets melting at terrfying scales.

            No subduction zone can do a Siberian Traps or CAMP

          • Masaya is an impressive beast for being a subduction zone volcano
            Its supply been estimated to be very high, but alot of the volume is degassed with open vents, its also perhaps the hottest lava of all subduction zone volcanoes being close to 1160 C it rises quickly from the source, without evolving. The 10 km3 basalt fountain plinians must have been a develish sight.

            Masaya’s magma is tholeiitic basalt! thats indicates large melting ammounts below the system, most subduction zone basalts are alkaline.
            One day Managua will be destroyed by lava flows or tephra falls.

            But a LIP it cannot do

          • Masayas older caldera is 10 kilometers long, and almost looks like a small version of a basaltic caldera on moon IO. Did this huge caldera now filled up by cones, form during one single catastrophic event?

            Masayas caldera looks like a twisted version of Kilaueas summit, just larger the caldera. Masaya is becomming a scary volcano, with a large magma pool, but I guess alot goes into passive fillings, Masaya is not known for any shield building, even if it haves the type of magma

          • The term flood basalt shouldn’t be used so lightly, it refers to basaltic eruptions of around 100-1000 km³, much bigger than anything any currently active volcano has done. They are also usually long-lived sustained pahoehoe flows that are fed from a mantle plume head.

            Some flows from volcanic fields like Undara or the North Hawaiian Arch resemble somewhat the eruption style of flood basalts but are much smaller in volume so can’t be considered to be true flood basalts.

            Laki is an oversized fissure eruption but I don’t think it should be called flood basalt either.

          • True flood basalts are VEI 8 effusive basaltic eruptions 1000 km3 or much more, and not at all acossiated with calderas, because they feed from very deep, not a shalllow chamber.

            These flows can reach lengths of 2000 kilometers during extreme chases during severe LIP events. Siberan Traps and Central Atlantic Magmatic Province are the most intense flood basalts on land since complex land life began.

            VEI 8 single Flood Basalts flows can be fast or slow.
            Many flood basalts are uniform thick single columnar sheets, that can be followed for 100 s of kilometers, likley feed by monster fissures and coud be mammoth big lava seas that damed and pooled. Some are very chemicaly uniform suggesting fast eruptive rates, their thickness is impressive without any lobing at all! suggesting faster without lobing at small scale.

            Some other single VEI 8 basalt flows are compund and pahoehoe like The DT Rahajamundry pahoehoe flow can be followed for 1500 kilometers across india, likley much longer without erosion. So some LIP flows was slow and long lived. Deccan Traps haves alot of pahoehoe, as well as the larger single fast flows.

            The debate between fast and slow emplacement of LIP flows rages on.

          • Ontong Java Plateau 100 million km3 in just a few hunderds of thousands of years, was formed by a superplume event, during “cretaceous superplume sourge” Probaly acossiated why climate during creatceous became extremely hot, but degassing from very active young mid ocean ridges is culprit too.

            Ontong Java Plateau had large eruptive rates, and massive so called
            ” submarine sheet flows” when lava flows so fast underwater, thats its not forming pillows and flows like it does on land flood basalt. They drilled in that LIP and the aquatic flows are indeed impressive thick sheets.

            Open lava rivers underwater was also seen in Kilauea in 1990 s
            https://www.youtube.com/watch?v=4U_gHaYBELE watch at 8:48 fast flowing river underwater. The java flood basalt must have flowed like crazy underwater during the faster events. Geologists alos says that OJB surfaced during cretaceous forming a land LIP too.

          • Africa haves a large magma influx, but the superplume is keept from melting at large rates by the thick and deep cratons. Africa haves 100 s of volcanoes and many haves large explosive calderas from sillceous alkaline exploisve events. The rising mafic magmas melts the continent or evolve themselves. Im supprised by lack of VEI 8 silliceous events in Africa, but alot in africa goes into passive rifting, but it does haves the thick crusts and often slow alkaline supplies that can form large evolved chambers. But perhaps alkaline magmas are made in too small ammounts to form a VEI 8 silliceous trachyte chamber. Seems like all VEI 8 evolved pyroclastic events are subalkaline and feed by large basments of basalts that slowly evolves

          • I probably should have said this but I tend to consider any fast effusive eruption, one where the average output is over 100 m3/s and 1 km3, a flood basalt. This includes Holuhraun and Leilani but not Pu’u O’o, and it also gives justice to the 1000 m3/s sustained eruption rate of the first few days of the Mauna Loa 1950 eruption, which is a ‘flood basalt’ if I have ever seen one just not impressive volume wise. Even though under 1 km3 I think it more than makes up for that in eruption rate.

            I also remember reading back when Holuhraun was active it fell into flood basalt territory for exceeding 1 km3. Its sort of like how a VEI 5 is still a huge eruption even though its 1000x smaller than a VEI 8.

            With all that out of the way Ithink Kluychevskoy will erupt on this scale one day, Tolbachik already has so its a proven possibility.

        • Correct, there is only a little bit of erupted Dacite in this group from my knowledge. But this is a young and developing system that isn’t there right now, but in 50k years (which is a short time span geologically) could easily be. And given the heat source, I would possibly wager it can go off a lot sooner than some of the supposedly more mature volcanic groups.

          Here is my thought on why it “checks off a lot of the boxes”.

          1. It has an absolute prolific heat source. If you group this volcano cluster assuming a singular deep source, it is easily the most prolific eruptor over the last 10k years.

          2. There is evidence of a slab gap, slab tear, and a deepening subduction plate here in the central Kamchatka depression. As Hector mentioned, these are items that are often related to flareups of many varieties.

          3. There is a notable spreading & rifting here. Hence the graben of the Central Kamchatka depression. Not dissimilar from Toba, this is an area of localized spreading over a highly active subduction ridge.

          4. There is evidence of potentially intense deep underplating here around the Moho.

          5. While more rhyolite / dacite is generally a good sign of a potential caldera, I think this can be a bit misleading since the ryholite & more viscous magma typically is erupted AFTER initial super-eruption. Most of these large caldera systems tend to be bimodal, and erupt large basalt eruptions between their super-eruptions. See Tarawera for a modern example of this behavior. In other words, there could be a very large amount of silicic crystal mush below the ground here that’s potentially eruptible and we wouldn’t know since it hasn’t gone super-eruption yet.

          6. We see large-scale doming here in a graben type area. Again, if you were to envision what Toba may have looked like before it started going “super”, it wouldn’t be tough to imagine it looking something like this.

          7. We get a classic scenario of prolific heat potentially melting lots of continental crust in a thinning zone. We’ve seen this story before. The question is whether the heat source can or will continue. If it slows down, this could easily fizzle out, but if it stays constant, I would find it hard to believe it wouldn’t eventually create some large scale caldera type activity.

          8. While the Klyuchevskoi group is still relatively Mafic, it’s neighbor just to the north Shiveluch shows that it’s easy for these to evolve into a more explosive silicic type system. Shiveluch is primarily dacitic with a huge track record of large scale dome building and VEI 4+ size eruptions. It probably wouldn’t be a bad idea to include Shiveluch into this group as a potential future developing caldera cluster in the Central Kamchatka depression.

          • And Tondano wont do a VEI 8 anywhere soon.. its too well vented and too suppyed now and too mafic in its products. Soptutan is a boiler valve.

            Shiveluch is impressive as heck, the most productive dacite volcano for now and signs it haves acess to large resovairs, but it seems too gas poor now and too vented?

          • The large calderas that I’m aware of usually have clear precursory dacitic or rhyolitic activity, crystal-poor lava domes and plinian eruptions from widespread vents which is somewhat different to the crystal-rich plug slowly growing at Shiveluch.

            Preceding silicic eruptions usually lasts from tens to hundreds of thousands of years.

            But I do agree with the Central Kamchatka Depression being a rift valley and a common reservoir feeding the group.

          • From what I can find KVG is not more prolific than the large plume volcanoes but its comparable, historically Hawaii is about 0.5-1 km3 erupted per decade so average about 7.5 km3/century up to 10 km3/century (50% of magma erupts from plume). Iceland, Afar and Galapagos are all about 5 km3 a century more or less. Kluychevskoy is very similar to Etna, which is typically about 1-2 km3 a century. Tolbachik is maybe 2 km3 a century if this past century now is typical but otherwise seems about the same range as Kluychevskoy. Bezymianny is maybe 1 km3 since waking up, a bit more maybe depending on how much of its big blast was new magma.
            So for being in a subduction zone Klyuchevskaya group is rather incredible but it doesnt displace Hawaii, it could be anywhere from 2nd to 5th, they all overlap after that it seems, its hard to tell because unlike Hawaii they rarely do long lived eruptions.

            That is why I suggested the possibility of a major basaltic eruption, fed by the common source directly and the entire combined edifice subsiding. 2012 eruption was actually like this but not a collapse and local to that area. If a lot of the active complex is actually formed in the Holocene then it may be a first time. Hawaii, Galapagos, Iceland and Afar have all had basaltic eruptions over 1 km3 since 1900 and over 5 km3 in the past 1000 years, and Iceland has had 1 over 10 km3. 1975 eruption at Tolbachik was at least 1.5 km3, so fits in this category, but I dont think a 5+ km3 flow has happened yet.

          • Well then theres 6 basaltic areas which can maybe pull off a flood basalt, though Nyamuragira hasnt had an eruption of 1 km3 or more so im going to put it at 6th place. Of all the locations though it probably has the best potential of becoming a flood basalt of traditional sense, something that could erupt a 1000 km3 flow, but not yet.

            If I was to guess, the next serious flood basalt, a 10+km3 eruption on land something like Laki, will be in Iceland again, but not for millennia. Its the only place you can actually get basaltic magma to collect in the 100 km3 volumes needed to drive such an eruption and also have it erupt on land. Mauna Loa in theory should be able to do this but it cant accumulate enough magma and maxes out at about 5 km3, everywhere else is submarine only for this scale.

  8. Toba must have been an insane event… so much volcanic ligthning! I wants a timemachine and long ex photographs of Toba in the darkness. How it looked like we will never know

    • So much bolts, your photos taken becomes a white mess with no value: go for short shutter speeds 🙂

      • IIRC, there’s an astro-photography technique devised for mitigating atmospheric disturbances. Take multiple, under-exposed pics in rapid succession, then stack those which align…

    • Im as dumb and fooled as its absoutley possible to get: I wants a Toba or La Garita to happen again.
      But I think everyone wants to see a +1000km3 event, and some arabian pyroclastic events was perhaps 20 000 km3, basicaly the volume of a young Hawaiian seamount blown out in a week.
      But these large pyroclastic events coud be many smaller eruptions thats behind one ash layer.
      Now its enough with blowing up the planet

      • The Sam ingnimbrite is 30 million years old, probably a bit of a stretch to jump to single eruption conclusion, a 20,000 km3 eruption is a VEI 9 and you need a magma body big enough to do that all go off at once. If that chamber was 2 km deep then it would have to be 10,000 km2 in area, which is 100×100 km. Its not absolutely impossible but any supervolcano (yes I had to use it) that is not active now probably should have the volume estimate be taken with a colossal grain of salt, many VEI 8 formations have likely not actually had a VEI 8, more a bunch of 7s merged to look like it.

      • Yes thats right: but curiosity is always fun. Looks like Toba was a massive fissure eruption along the caldera rim.

        Basicaly fissure open up and pyroclastic currents wells all over northen Sumatra.

        A large plinian phase must have also been present to deposit thin ash layers in Africa from it.

        These are huge events, but best to leave for the mind imaginary to see them

    • A VEI 8 evolved phonolitic chamber is an impossibility, since such alkaline melts are produced only in minior amounts.

      But Erebus is really hyperactive for souch chemistry, but its feed by evolving basanitic melts. Erebus have done some seriously large phonolitic caldera plinians before perhaps sizable VEI 6 s, much larger than Laacher See phonolites. Mt Erebus Largest explosive caldera is perhaps 10 km wide and now filled by a younger phonolitic strato – shield. Erebus is a really weird volcano, with the only higher viscosity lava lake on the planet, that’s perhaps more viscous than etna

      • Temperature is probably more important than composition, from the videos I have seen the lava at Erebus is very hot as it glows bright orange in daylight, suggesting a temperature of well over 1000 C. Technically glass is a sort of synthetic phonolite, being sodium calcium silicate, at 1000 C glass is a fluid that flows easily, even if it is a silicic ‘lava’. I would guess that if silicic magma was ever erupted as hot as basalt usually is it would be hard to tell the difference, but rhyolite has higher heat capacity than basalt so heating it so much would be difficult.

      • Yes Erebus is a rather hot Phonolite, but its still much more viscous than Erta Ale and Halemaumau/ Holuhraun basalts

        Erebus lava lake haves a rather taffy look. It cannot slosh and bubble, because its too viscous. Instead it degas by slow bubble bursts and Strombolian explosions. ”Slug gas flow burps in a Phonolite magma column” its common that the entire lava lake is blown up during a gas slug burst. The viscosity is probably higher than Etna, Erebus is also rich in Big anortoclase crystals.

        Temperature is very important, Etna haves lower silica than Hawaii, but much higher viscosity, because of Etnas lower temperatures.

        An 1250 C Ryholite would probably be quite mobile and fluid enough to be penetrated by a iron pipe

        https://m.youtube.com/watch?v=R40m04jPDZI

        https://m.youtube.com/watch?v=LUy8vtk6OgE

        • That would be expected for that composition, for it to be a bit more viscous. It looks very similar to the lava at Hekla, which is andesite at about 1100 C, probably Erebus is similar. The lake is only 20 meters wide, the bursts are not gigantic, the spattering on a lot of the other lava lakes is similar in scale to the bursts here.

          Only slow etna eruptions are viscous, the 2011-2015 fountaining events, which created the new southeast crater, saw flows up to 8 km long which were erupted in a few hours. Fountains erupt at about 1120 C or higher, so the lava probably is not that different to plume basalt in appearence but as far as I know no up close shots of the flows exist due to the high risk with such fast flows. The 2011-2015 eruptive event was very similar to the fountaining that created Pu’u O’o.

          • A small hotspot and slow rifting… little melt production deep down.
            Continetal rifting and plume. Base magmas are ultrabasic basanite that evolves into phonolites and tephriphonolites. Antarticas continetal rifting and plumes perhaps hides many sillic – VEI 6 – VEI 7 calderas

      • calcium and sodium are added to glass to lower the melting points and viscosity
        it gets soft at 700 C deep red. You can melt soda glass in your home fireplace if its well stocked with wood and good draft
        I often gets up up
        960 – 1060 C in my fireplace if its full draft and loots of wood, souch firing makes a great evening in the living room. At 1200 C soda glass flows rather very easly

        Pure white Quartz – granit sand glass thats a diffrent matter! extremely hard to melt and furnaces needs to be fired to over 1600 C ( blinding whitish yellow ) to make it melt. Its hard to work with Quartz sillica glass. Souch hard glass are often use as observation spyhole glass in gabrage to energy incenirators. As well as ornamentation and crystal balls.

        White sillica foam was used as Space Shuttle Tiles, able to resist the extreme heat of reentry. But these foam blocks where rather brittle and crumbly

        • I fuse glass art and full fuse is about 1480 f ,full fuse is a complete melt it will take staked glass to a puddle with smooth surface and rounded edges

  9. Very recent fissure eruption on Mars.
    I knew that Mars is still volcanicaly alive. Mars is a quite large object, more than Half of Earths diameter, no way for an object that size to have cooled competely yet. Mars have cooled more than Earth because of smaller mass, but its certainly large enough to store significant ammounts of heat. Cerberus Fossae likley is Mars youngest basaltic deposits. But Mars is smaller than Earth and is very much less active because of that, only erupting infrequently. But its not dead as Earths smaller moon is.
    But size is still important, if you are
    not tidaly heated.

    https://earthsky.org/space/mars-cerberus-fossae-young-lava-flows-volcanic-activity

    http://astrobiology.com/2020/11/evidence-for-geologically-recent-explosive-volcanism-in-elysium-planitia-mars.html

    https://www.discovermagazine.com/the-sciences/first-evidence-of-a-recently-active-volcano-on-mars

    https://www.google.se/amp/s/www.nytimes.com/2020/11/20/science/mars-volcano-eruption.amp.html%3f0p19G=0232

    • Mars is between Earth and the Moon in cooling rates. Not as dead as the moon, Not as active as the Earth. Since its size is between these two.

      Mars maybe in the last phases of its volcanic life, erupting very infrequently now. The planets litosphere is getting extremely thick now.

      • That coud be 100 000 years, blink of an eye in geological time!

  10. Mauna Loa says don’t ignore me.

    2020-12-05 14:56:17 1.7 -1.6
    2020-12-05 14:22:56 2.8 3.8
    2020-12-05 14:14:47 1.2 -3.3
    2020-12-05 13:48:58 1.3 -1.3
    2020-12-05 13:39:19 2.1 -1.4
    2020-12-05 13:32:28 1.7 0.9
    2020-12-05 13:26:25 3.3 -1.1
    2020-12-05 11:54:13 2.5 2.5
    2020-12-05 11:23:15 2.3 -1.7
    2020-12-04 18:04:20 1.8 -2.4
    2020-12-04 17:44:24 4.1 4.7

      • The area around Kilauea has shown a bit of uplift since September. At the same time to rift calmed down, so I interpret this as a reduced channel width along the rift, affecting the pressure balance in the plumbing system. In the last few days the change has focussed on the southern caldera, as if magma was squeezed from one chamber to another. (That is speculative!) It was much too fast for new magma to be involved – this was a change in location in quite a shallow chamber, perhaps the same one involved in the DI events. The uplift is still very small compare to what it can do: this was not a large event. My guess? A sudden partial blockage in the outflow channel.

  11. Dunno about VEI8 but I’d bet anyone that Agung will have at least a VEI6 eruption within my lifetime, especially with that plug there. Given that Batur, Rinjani & Tambora are very close by and all did a VEI7, and the crust under Bali is supposed very thin, it’s almost a given.

  12. An interesting story about the earthquakes and eruptions in Hawaii, from August 1868 and May 1877…

    Life in Hawaii, by Titus Coan
    Copyright ©1882, 1997 (electronic edition by Edward J. Coan)

    The Eruption of 1868 from Kilauea The March and April Earthquakes Land-Slips Destruction of Life and Property The Lava-Stream Bursts from Underground The Volcanic Waves of August, 1868, and of May, 1877.

    FROM time immemorial earthquakes have been common on Hawaii. We have felt the jar of thousands. Most of these shocks have been harmless. A few have broken a little crockery, cracked plastering, and thrown down stone walls.

    But on the 27th of March, 1868, a series of remarkable earthquakes commenced. Kilauea was unusually full and in vehement action. Day after day from March 27th and onward, shocks were frequent, and growing more and more earnest. At 4 P.M., April 2d, a terrific shock rent the ground, sending consternation through all Hilo, Puna, and Kau. In some places fissures of great length, breadth, and depth were opened. Rocks of twenty to fifty tons were sent thundering down from the walls of Kilauea, and massive boulders were torn from hill-sides and sent crashing down upon the plains and valleys below. Stone houses were rent and ruined, and stone walls sent flying in every direction. Horses and men were thrown to the ground; houses tilted from their foundations; furniture, hardware, crockery, books and bottles, and all things movable in houses were dashed hither and thither, as of no account. It seemed as if the ribs and the pillars of the earth were being shattered.

    I was sitting, as at the present moment, at my study-table, when a fearful jerk startled me, and before I could arise, a jar still more terrible caused me to rush for the stairs, and while going down, such a crash shook the house that I supposed the roof had fallen.

    Going out of doors, I found my wife standing at a distance from the house, watching with an intense gaze its swaying and trembling, while the ground rose and sank like waves, and there was no place stable where hand or foot could rest.

    When the shocks intermitted a little, I went upstairs to witness a scene of wild confusion. A large bookcase, seven feet high by four wide, with glass doors, and filled with books, lay prostrate on the floor near where I had been sitting, with the glass broken into a thousand pieces.

    My study-table, eight feet long, and loaded with large volumes, was thrown out from the wall into the center of the room, with one leg broken square off, and the books and papers scattered on the floor. Another bookcase, fastened to the wall, was rent from its fastenings and thrown out near the table, and three of the sleepers which supported the floor were broken by the fall of the case.

    The shaking continued all night, and most or all of the Hilo people spent the night out of doors, fearing to remain in their houses. Some said they counted a thousand shocks before morning, and so rapid were these shocks, that the earth seemed to be in a continuous quiver, like a ship in a battle.

    But the heaviest blows fell on Kau, the district lying south of us on the other side of Kilauea. There the earth was rent in a thousand places, and along the foot-hills of Mauna Loa a number of land-slips were shaken off from steep places, and thrown down with soil, boulders, and trees. In one place a slide of half a mile in width was started on a steep inclined plane, till, coming to a precipice of some 700 feet, on an angle of about seventy degrees, the vast avalanche, mixing with the waters of a running stream and several springs, was pitched down this precipice, receiving such fearful momentum as to carry it three miles in as many minutes. Ten houses, with thirty-one souls and five hundred head of cattle were buried instantly, and not one of them has been recovered.

    I measured this avalanche and found it just three miles long, one-half a mile wide at the head, and of a supposed average depth of twenty feet.

    At the same time the sea rose twenty feet along the southern shore of the island, and in Kau 108 houses were destroyed and forty-six people drowned, making a loss of 118 houses and seventy-seven lives in that district, during this one hour. Many houses were also destroyed in Puna, but no lives were lost. During this awful hour the coast of Puna and Kau, for the distance of seventy-five miles, subsided seven feet on the average, submerging a line of small villages all along the shore. One of my rough stone meeting-houses in Puna, where we once had a congregation of 500 to 1,000, was swept away with the influx of the sea, and its walls are now under water. Fortunately there was but one stone building in Hilo, our prison; that fell immediately. Had our coast been studded with cities built of stone and brick, the destruction of life and property would have been terrific.

    This terrible earthquake was evidently caused by the subterraneous flow of the lavas from Kilauea, for the bottom of the crater sank rapidly hundreds of feet, as ice goes down when the water beneath it is drawn off. The course and the terminus of this flow were indicated by fissures, steam, and spouting of lava-jets along the whole line from Kilauea to Kahuku in Western Kau, a distance of forty miles, and I have found foldings and faults in several places.

    During these days of subterranean passage, the earth was in a remarkable state of unrest; shocks were frequent, and it was asserted by trustworthy witnesses that, in several places, the ragings of the subterranean river were heard by listeners who put their ears to the ground.

    On the 7th of April the lava burst out from the ground in Kahuku, nine miles from the sea, and flowed rapidly down to the shore. The place of outbreak was in a wood on one of the foot-hills of Mauna Loa. Travelers bound to Hilo came up to this flow on the west side, and were not able to cross it, but were obliged to return to Kona and come via Waimea, a circuit of one hundred and seventy miles. A fissure of a mile long was opened for the disgorgement of this igneous river, and from the whole length of this orifice the lava rushed up with intense vehemence, spouting jets one hundred to two hundred feet high, burning the forest and spreading out a mile wide. The rending, the raging, the swirling of this stream were terrific, awakening awe in all the beholders.

    Flowing seaward, it came to a high precipice which ran some seven miles toward the shore, varying in height from two hundred to seven hundred feet, and separating a high fertile plain, of a deep and rich soil on the left or eastern side, from a wide field of pahoehoe hundreds of feet below on the right or western side.

    Before the flow reached this precipice it sent out three lateral streams upon the grassy plain above, which ran a few miles, and ceased without reaching the sea. But the larger portion of the igneous river, or its main trunk, moved in a nearly straight line toward the shore, pouring over the upper end of the precipice upon the plain below, and dividing into two streams which ran parallel to each other, some hundred feet apart, until they plunged into the sea. These streams flowed four days, causing the waves to boil with great violence, and raising two large tufa cones in the water at their termini. They formed a long, narrow island, on which they enclosed thirty head of cattle, which were thus surrounded before they were aware of their danger, and it was ten days before the lava was hard enough to allow them to be taken out of their prison. During this time they had no water, and were almost maddened by the smoke and heat. Several cattle were also surrounded on the upper grassy plain, where they were lying down to ruminate or to sleep.

    The owner of the ranch, with his wife and a large family of children, was living in a pleasant house surrounded by a wall, with a fine garden of trees and plants, near the center of this beautiful grassy plain, and while sleeping at night, unconscious of danger, one of these lateral streams came creeping softly and silently like a serpent toward them, until within twenty yards of the house, when a sudden spout of lava aroused them and all fled with frightened precipitation, taking neither “purse or scrip,” but leaving all to the devouring fire. The lady was so overwhelmed with terror that had it not been for her husband on one side and another gentleman on the other, she must have fallen and perished in the lava.

    The family, crossing a small ravine, rested a few moments on a hill near by. In ten minutes after crossing the ravine it was filled with liquid fire. Their escape was marvelous. In a few minutes the house was wrapped in flames, the garden was consumed, and all the premises were covered with a burning sea.

    A little farther down this green lawn was the hut of a native Hawaiian. As the fiery flood came within fifty feet of it, it suddenly parted, one arm sweeping around one side of the house and the other around the opposite side, and uniting again left the building on a small plat of ground, of some three-quarters of an acre, surrounded by a wall of fusion. In this house five souls were imprisoned ten days with no power to escape. All their food and water were exhausted. Small fingers of lava often came under the house; it was a little grass hut, and they were obliged to beat out the fire with clubs and stamp it with their feet.

    Piles of burning scoria were heaped around this house, as high as the eaves, and in some places within ten feet of it. I afterward visited this house, and found its inmates alive and rejoicing in their deliverance.

    A little further on, and this lava stream came near the ruins of a stone church, which had been shaken down by the earthquake of April 2d. The walls were a heap of ruins, and the roof and timbers were piled upon the stones. Again the flood opened to the right and left, swept close to the débris of the church, and united again below, leaving all unconsumed.

    The same earthquake demolished a large stone church in Waiohinu, the central and most important mission-station in Kau, and so rent the house of the pastor, the Rev. John F. Pogue, that he, with his family, fled to the hills, and soon after left the district to return no more. Other homes also were left desolate, the terrified inmates seeking abodes elsewhere.

    On the 14th of August, 1868, a remarkable rise and fall of the sea commenced in our harbor, and continued for three days. The oscillation, or the influx and efflux of the waves occupied only ten minutes, and the rise and fall of the water was only three to four feet. What rendered this motion of the water remarkable was its long continuance, and the short intervals of the rise and fall with no apparent cause.

    Another volcanic wave fell upon Hilo on the morning of the 10th of May, 1877. From a letter written by my wife (Mrs. L. B. Coan) I copy the following extracts descriptive of the event: “A chilly, cheerless night shuts down upon a day that has had no parallel in kind in my previous experiences. I was just rousing from quiet slumbers this morning, not long after five, when heavy knocking at our door hastened me to it. There stood Kanuku, almost wild with excitement, and so breathless she could hardly give form to the words she poured forth; but I gathered their substance. A volcanic wave had swept in upon the shore; houses were going down, and people were hurrying mauka (inland) with what of earthly goods they could carry.

    “We hastened to the beach. People on foot and on horseback were hurrying in all directions; men with chests and trunks on their backs, women with bundles of bedding and clothing under which they staggered, grandmothers with three or four year old children on their shoulders, and mothers with little babes, all in quest of safety and a place to lodge their burdens. Arrived at the foot of our street what a sight we beheld! Houses were lifted off their under-pinning and removed a fathom or more some had tumbled in sad confusion and lay prone in the little ponds that remained of the sea in various depressed places. Riders at breakneck speed from Waiakea brought word of still more complete ruin there; the bridge, they said, was gone.

    “We walked on toward the Wailama. Then a shout, and we looked back to see the waves rising and surging landward, so we dared not linger, but turned on our track, for a better chance of escape should the sea again overpass its bounds.

    “People wading in water where their homes had stood half an hour before, gathering up goods soaked by the brine, and begrimed with mud, men in wet garments who had had to swim for their lives, and women with terror in their faces caught up the refrain of a death-wail that reached our ears from the region of Kanae’s place, and the word flew from lip to lip that old Kaipo was missing. Asleep, with Kanae’s babe pillowed near her when the wave came upon them, she had wakened, and hastening out of the house found herself in deep water. Holding the little one above her head, she had courage and strength to keep it safe till the mother swam for it, and then, no one knows how, the old woman was swept out to sea, and hours after, the body was found at Honori.

    “About nine o’clock, the rain which had come in infrequent light flurries before, began to pour in earnest, and has fallen in such pitiless inclemency through the day, that it has added to the discomforts of the poor, homeless wanderers, and to the general gloom that hangs over our little town.

    “Mr. Coan has been out much of the time here and there with words of sympathy and comfort. Rebecca Nakuina told me the natives said they were safe wherever he was. One poor old man came to our door and asked in most pathetic tones if it was true that Mr. Coan had said that at noon there would be another and heavier wave, and went away comforted when assured that he had not.

    “A large barque at anchor in our harbor was tossed about most marvelously at the very mercy of every efflux and reflux wave. For hours she writhed under this restless tossing, one moment pointing her prow toward Puna, and the next in the opposite direction, running back and forth the full length of her cable, like a weaver’s shuttle, sometimes careening so far that we feared the next moment to see her on her beam ends, and then struggling to right herself, and for a little recovering her usual position, only to repeat these movements

    “May 11th. The birds sang and the sun shone this morning, as if there were no sorrow here. But it was a great blessing that the day was fair; the sunshine was needed for heart-warmth and for drying what of clothing and household effects had been collected from the mud and slime in which they were found.

    “We went over the same ground on the nearest beach that we visited yesterday, only to realize more fully the wild havoc that had been made.

    “‘What shall I say of what we saw on the other side of the bay! If I tell you that Mr. Coan was bewildered, seeing no familiar object by which to get his bearings, so that he exclaimed: Where are we! You will understand something of what destruction must have gone on there. But unseen it can not be realized, the dreariness and desolation of a little region that was so late one of Hilo’s prettiest suburbs. Not a house standing on all that frontage. Waiakea bridge had been carried a hundred rods or more from its abutments. Even the little church had been set back some two hundred feet, tolling its bell as it went, while the luna’s house that before nestled under the shade of the pride of India trees on the grassy bank had borne it company, and fallen into shapeless ruin at the very side of the almost uninjured church.

    “At this spot the people began to gather about us, so sorrowful in their homelessness, that their voices and ours choked as we exchanged alohas. Some of them led the way to a hut, too small to be a shelter, but under whose low roof we found a mother sitting by the corpse of her little one that the waters had not spared to her. Close on one side, an old man lay groaning with the pain of fractured ribs and a broken leg, and on the other side, a heap of something, I could hardly tell what at first, lifted a battered head to tell us how he had been thrown upon the rocks and they had bruised his skull.

    “An Englishman’s escape from death seems wonderful. We visited him and found him suffering greatly, but able between groans and gaspings for breath to tell us something of his experience.

    “I got caught, sir, he said. I should have escaped if I hadn’t gone back after my money; when I came down-stairs the roller had hit the house, and before I could get out of the door, the house had fallen upon me. I was dreadfully bruised, and you see, sir, as the wave took the house inland, it kept surging about with me in it, and getting new knocks all the while. And what of the money was it saved? Oh, no, sir, it all went, six hundred dollars. It was all I had, and I am stripped now and I’m past working, seventy-seven years old. Kneeling by the poor man, Mr. Coan offered an earnest prayer. We left him feeling that he was very likely past working much longer.

    “Five lives have been lost; twenty persons are more or less injured. Forty-four dwellings are demolished, and one hundred and sixty-three people left homeless, their means of procuring sustenance snatched from them. Had the wave fallen in the darkness of the night, many more must have perished. Daylight revealed the almost silent approach of the danger, and most had time to flee. I am thankful, if it must happen, that this has occurred before our going down to Honolulu, so that Mr. Coan is among his people to comfort and direct them. Only a few Sabbaths ago he preached a sermon on laying up treasure where thieves could not break through and steal. Who thought then of this thief?”

    Deep sympathy was awakened in our whole community for those who suffered by this calamity. Food, clothing, blankets, were given in abundance. The report of the disaster spread over the islands, and help came from every quarter. His Excellency John Dominis, Governor of Oahu, and Her Royal Highness Lydia Dominis, the king’s sister, were commissioned to come to our aid with the donations from Honolulu. A judicious distribution of money, clothing, lumber, etc., was made among the people, and thus encouraged they went cheerfully to work, and in a few months most of the losses were repaired; better houses were built, and the sufferers seemed more prosperous than before.

    • Interesting the tsunami of 1877, Mauna Loa had a major submarine eruption earljer in that year but on the other side of the island, was there a large earthquake in the Pacific that year? Maybe it was a freak weather event, like a rogue wave making landfall which is a possibility in an oceanic environment like this.

      Its also interesting that the eruption of 1868 was entirely attributed to Kilauea even though when HVO was built it was believed Kilauea was a mere satellite of Mauna Loa, seems like the point at which Kilauea lost its fear factor was in the late 1800s, or even the turn of the century, and now seems it has re-aquired it. The mention of multiple eruptions southwest pf Kilauea is also interesting, only one tiny flow on Kilaueas southwest rift is of that year, and the eruption on Mauna Loa also seems only to have erupted at the obvious vent, theres actually a lot of reports of lava flows southwest of Kilauea which are not geologically correlated to that date.

      • The dyke that went down the southwest rift of Kilauea in 1868 only erupted briefly at Kilauea Iki and from a few tiny pahoehoe flows down the flank. However its path would have been rented by cracks and steaming which confused people of the time into thinking those fractures connected to the outbreak at Kahuku that was actually from a different dyke.

        • Yes that is true, the Kahuku eruption was most certainly from Mauna Loa. It is more that it was actually attributed to Kilauea at all, showing that it was still considered a dangerous volcano unlike when HVO was founded when Mauna Loa was the volcano that everyone was scared of and Kilauea was just a fancy tourist attraction.
          That view seems even now to be the predominant view at HVO, the attitude that 2018 is ‘just’a prelude to a Mauna Loa eruption seems widespread still today. Mauna Loas next eruption will likely be significant in volume with the length of repose so far but unlikely to do anything, quite opposed to a second fissure 8 or a summit plinian eruption at Kilauea.

      • In 1975, immediately after the MERZ earthquake there was a piddly eruption at Kilauea’s summit, along with a massive deflation of the volcano. Taken in that context Kilauea’s 1868 activity isn’t that unusual.

        • It is more unusual being that such a big quake happened so soon. Kilaueas last big flank collapse happened in 1823 and that years eruption was from the entire magma column rapidly draining out of the fault. Most data says the Keaiwa eruption was very passive with lava literally just flowing from the ground but the 1868 eruption at Kahuku looks visually very similar at the source and is known to have had vigorous high fountaining to hundreds of meters high by some estimates. My guess is the Keaiwa fissure was similarly impressive, though being degassed there would be little windblown tephra.

          Both eruptions were like mini flood basalts, the only similar event in recent years was the August 2011 flow from Pu’u O’o but that was not nearly so voluminous. I suspect both eruptions are much larger than the terrestrial volume estimates, probably among the biggest eruptions of the historical period in Hawaii. The stories of how fast the 1868 flow was is really very scary when you realise that slope is the same one Ocean View estates is built on…

          • Comparing a single volcano to a flood basalt completely misses the point. You cannot use a word devised for 1 million km3 for something 1 km3 in size.

          • I dont know if this was a reply to my other comment that misplaced but I actually didnt come up with the idea of flood basalt referring to a flow of 1 km3 in size, I read it way back when Holuhraun was active and passed the 1 km3 mark. I am actually not aware of a specific definition of flood basalt that excludes historical flows, really it just seems to be any basaltic lava flow that is erupted at a huge rate so it is emplaced as a single unit and has a volume high enough to count as a ‘big’ eruption – which is arbitrarily 1 km3. The only word I have found that actually does refer only to massive volume volcanism is large igneous province, which Hawaii is not usually considered but probably should be given its size and age. It also seems to be that a lot of gigantic flows are actually pahoehoe flows, not a’a flows, so probably dont erupt at huge rate. Its very poorly defined which is why its confusing.

            I should mention I dont think the eruptions in 1823 and 1868 were multiple km3 in size or even close to 1 km3 in size, but the official volumes (0.04 and 0.12 km3) are only what is on land. Both eruptions were very fast, caused collapses and flowed into the ocean, most of the volume is offshore and probably increases the total a great deal, though Hector probably will have a better idea of all of that stuff.

            🙂

    • My French is bit rusty, but the gist seems to be there was ongoing tectonic activity, then some deep seismic signals in april 2019, thought to be a magma recharge at depth, and now seeing shallow activity relating to the reactivation of the hydrothermal systems. However, no deformation recorded as of yet, but the change in seismicity warranted the change in alert level. Interesting

      • The precursors to the 1929 eruption was seismic activity, followed by phreatic activity.

    • Is there a risk of flank collapse at Pelee? It doesn’t look all that stable, visible faults, slightly offset.
      100,000 people live within 15km!

      • Don’t know, but there is a very real risk of a pelean eruption, named after what happened in 1902. A repeat of that event could wipe out surrounding populations in an instant.

        • Not forgetting the remote possibility of another VEI-5 full Plinian event like it has done a number of times… that would be…. terrible!

        • I have seen suggestions the 1902 eruption was a full lateral blast, not simply a dome collapse. The mountain had a massive ravine in the side after destroying St Pierre, which later was filled in by domes.

          It really makes you wonder why St Pierre was rebuilt…

          • As far as I remember 1902 erupted from a deep crater, it was certainly a blast and maybe somewhat lateral directed. Lateral blast is more or less a synonym for pelean.

          • From memory, there was a lava dome or spine that collapsed, which caused the pyroclastic flows.

            By the time the pyroclastic flows reached St Pierre, they were horizontal.

          • I have wondered who would sleep well having read reports of the 1902 eruption, those photos would be always on my mind

    • Mt. Pelee (aka Montagne Pelée, or “Bald Mountain” – pretty apt, especially for an active volcano!) has dished up quite a number of VEI-4s in the past several thousand years, the recent of course being the one in 1902.

      If Pelee was to show serious signs of new activity with potentially serious consequences, St. Pierre and the local areas around the volcano would be evacuated for sure. St. Pierre is only a shadow of what it once was pre-1902. Back then, it was the economic capital of Martinique. Today, it only has just over 4,000 people. The capital of this French overseas department is now Fort-de-France, pop. over 80,000 – and also located at a safer distance.

      Obviously, like the locals of Pompeii and Herculaneum over 1800 years before, people didn’t realize just how dangerous this volcano was, and on top of that, local politicians were more concerned about votes.(there was an election scheduled at the time). People weren’t even allowed to leave the city, either!

      With volcanology as a science in its infancy at the time, Mt. Pelee was probably the first volcano in which pyroclastic flows were first identified and seriously studied in detail in modern history.

      • The 1902 was no ordinary VEI-4 though, it has been very long since science had to deal with an eruption as violent as Pele. It took a few minutes for Pele to devastate Saint Pierre and kill 28,000 people. This is taken from Wikipedia:

        There are unnamed eyewitnesses to the eruption, probably survivors on the boats at the time of the eruption. One eyewitness said “the mountain was blown to pieces – there was no warning,” while another said “it was like a giant oil refinery.” One said “the town vanished before our eyes.”

        • Certainly, the definition of ‘warning’ will have changed in the intervening 120 years, but there are people now who will ignore even the most precise and explicit warnings. I see this a lot with mid-US tornadoes–eight days of forecasts, watches eight hours before the first thunderstorm, warnings sixty minutes before a tornado touches down–and still there are people who were watching Netflix or listening to podcasts instead of paying attention to local media who say “we din’t get no warnin’!”

          They want Jim Cantore or Reed Timmer to knock on their door an hour beforehand and inform them that a tornado is going to hit their house–theirs and no one else’s–before they will take on some level of personal responsibility.

          • I have read several books on this eruption, it seems there had been a previous minor eruption a a decade or so earlier. A science teacher and other men of science told people it was nothing to be very concerned about. Excursions to the old cauldera were even scheduled ! Given the dome or spine that grew after the main event I believe it was dome collapse, Google the tower or finger of Pelee it is the most unusual formation I have ever seen.

        • I think that by warning the witness meant the mountain was looking calm (from their perspective) and then it blew suddenly, dooming Saint Pierre and its inhabitants.

        • Montagne Pelée was not that calm before it destroyed Saint Pierre… The had been phreatic eruptions before, as well as a deadly lahar. Il was though that topographic barriers would protect Saint-Pierre, and that would have been true for minor pyroclastic flows. No one expected an eruption of that magnitude. It is true, though, that upcoming elections detered local authorities from evacuating the city.

          • The very saddest part of this is that the French power base on island sent poor black laborers back into the danger zone telling them the aid sent by other countries would not be given them unless they went back to where they lived before the eruption. When that massive dome collapsed many of them payed with their lives for the little food they received

  13. Roots of felsic caldera volcanism, discussed in earlier post by me: trying to melt sillicous felsic rocks.

    The high sillica coarse grained swedish plutonic rocks are almost impossible to re – melt into magma. I remeber when I tryed with an 1600 C torch and small gravel did not melt, large crystals of quartz sillica makes it hard i think.
    Basicaly ryholites and dacites thats been stuck undeground and slowly cooled.

    Magma chemistry and evolution are complicated as heck. generaly begins with a basalt with the more mafic minerals thats crystalized out and leaving a more sillicous melt and it goes from there to granites and ryholites as well as dacites and granidiorites on the way up depending on the Sio2 content.

    Hard as heck to melt, specialy the coarse felsic pegmatite pebbels, thats basicaly large quartz crystals, to melt these you needs a welding or plasma cutter. Coarse grained white granites can be almost pure sillica, they are hard to melt! The ”White Granites” are the hardest with large quartz crystals. Some felsic plutonic rocks in continents are almost competely white, these are hard to re – melt

    Its so amazing that souch sillica rich quartz full plutonic rocks… can be formed from an ultrabasic / ultramafic mantle!

    • Dacite flow been also found on Mars.. proof thats its formed by diffrentiation of basaltic magmas, with or without tectonics. On Earth Subduction tends to form felsic magmas

      All the Sio2 rich light pale plutonic rocks are originated from an ultra – mafic mantle even if mantle pedriotite and crustal granites are chemicaly aliens towards eachother!

    • Try adding water and CO2 to your granitics and keeping it under high confining pressure. Suddenly things are mobile at MUCH lower temps. Its when you take the pressure off that things get messy in a hurry, as the silica and the volatiles want to go their separate ways 😉

      • Yes wet Granites are apparently molten down to 700 C in the mantle… water

        Dry Granites needs at least 1700 C to melt back into Ryholite – Obsidian

      • Melting a white granite or pegmatite white granite texture is going to be very hard… all the sillica

        Pure Quartz is a fortess against heat often only melted again on earths surface by asteorid impacts

        Quartz Glass is difficult to work with because its very high melting points

  14. Geologists Think They’ve Found an Alaskan Version of Yellowstone’s Supervolcano… An interesting article on science alert. Com. I do not knew how to make a link here.

  15. Mauna Loa says look at me!

    2020-12-08 00:50:18 2.8 -0.8
    2020-12-08 00:32:10 1 3
    2020-12-08 00:25:17 3 -1.7
    2020-12-08 00:22:13 2.3 3.4
    2020-12-08 00:13:06 2.3 -1.2
    2020-12-08 00:10:51 1.9 2.6
    2020-12-08 00:00:46 3.2 -1.9
    2020-12-07 23:34:07 1.8 -1.1

    • I have always wondered what that swarm actually is. Its not deep but also not really related to the summit, its sort if just there. Its been there for a really long time too, at least the 1970s. Its interesting that it has become so active right after a sizable new intrusion at Kilauea, sounds like a tectonic feature a bit like the Ka’oiki faults. I dont know if that particular area has a name.

      I think we will see Mauna Loa erupt within a few years at this rate, I dont know what the supply rate is, but even if its only 0.01 km3/year that is nearly 0.4 km3 since it last erupted.

      • Well apparently the estimated average supply rate to Mauna Loa since about 4000 years ago is twice what I guessed above, its about 10% of the hotspot production or 0.02 km3/year. HVO did say it passed 1984 levels a few years ago so makes some sense. It must have been much higher in the mid 1800s though.

        I noticed Mokuaweoweo has nearly filled entirely, I would not want to be in Ocean View if ever a dike goes down the southwest rift… The early 1700s Hapaimanu flows cover a lot of the area and would have been an eruption way bigger than Holuhraun or fissure 8. If that happens again in the same place as the 1907 eruption then we get the effusive equivalent of Pelee and St Pierre…

    • This swarm is close in location to the previous one, but is only half as deep (measured from the surface). It is perhaps a fault within the edifice, perhaps taking some of the strain from the settling of the mountain two weeks ago

      • I read the recent report about the 4.1 quake there a few days ago, there is apparently not a particular name for that location, in either Hawaiian or English. The bit that is confusing is the quakes form lines as expected for a fault but the line isnt radial to the summit, its more in line with the southwest rift but also not parallel.

        • The two groups of earthquakes both form a line that points at a location just south of the caldera. In fact pretty much the secondary crater there that joins up with the caldera. I think this is also the location where the inflation of the past years was centred. The nearest GPS shows continuing inflation here, but with a bit of motion towards the caldera. That is caused by the deflation of a shallow magma chamber underneath the caldera. So I think it was induced by the relaxation of the stress. The swarm started at the bottom, where the stress was highest, and migrated up and towards the ridge. I haven’t tried to see whether the slop of the mountain changes over the location of the swarm.

  16. On the idea / concept of a hypothetical VEI-9 eruption, I had some thoughts to share.

    First, I think it is likely that we have actually had a VEI-9 eruption at one point during the earth’s history. Keep in mind, the earth is 9 billion years old, and at one point, we were far more volcanically active than we are now. Even if we were to take just the last 1 billion years where life has thrived, I would still say it’s likely. Outside of a select few very very very large eruptions we have unearthed from the way distant past, there are likely far more eruptions that have never (and will never) be unearthed that were potentially massive.

    Second, I don’t see any reason why a VEI-9 eruption would be impossible. You would normally think that the “roof” would the constraint, but that goes out the window when you realize that most of the magma chambers for VEI-9 sized eruptions likely form at a very deep level, and only later get exposed to being able to erupt when the overlying crust thins to the point that it becomes very weak. If you simply get a big enough piece of underplated and heated crust along with a significant rifting episode above it, there is no reason it can’t go even larger than we have currently been able to document.

    Obviously, you need a very wide spread heat source below a portion of the crust, but I don’t think the eruption trigger would be impossible to get going all at once (relatively speaking) provided that enough of that crust is in a state that it can potentially be eruptible. Keep in mind, the process of punching a hole in the overlying crust adds further depressurization, which can convert more magma into eruptible state.

    • Earth is 4.6 billion years old, not 9. But yes I think a VEI 9 is possible but it would also be very hard to prove it wasnt just a layered deposit of eruptions of lesser magnitude. Probably a lot of VEI 8 calderas are made by merged VEI 7 calderas that occurred close in time but on human timescales would be decades apart or something like that, as is the case for the Huckleberry Ridge tuff at Yellowstone.

      I think a 10,000 km3 single eruption is more likely to be basaltic, then you just need a plume, no need to melt crust though that probably also happens when plumes rise under a continent. Probably some flows during the breakup of Pangea were of this scale.

      • Yikes, that was way off. Apparently citing stats from my memory alone isn’t the most accurate way to do thing haha.

      • Central Atlantic Magmatic Province must have been an awsome sight! the largest land based LIP since life got up on land. The lava flowed 3000 km west – east and 6000 km south. Building up a plateau with a volume of 11 million cubic kilometers, in just a few 100 thousands of years. Fissures many hundreds kilometers long, curtains of blazing fire strecth across the whole horizon. Basicaly Holuhraun lava deserts over an area as large as Africa I think. The greatest fissure eruptions in perhaps the last billion year. Siberian Traps was probaly just as intense, but CAMP was larger. The lava fountains I seen in person in Etna and Reuinion and the flows in Hawaii… are tiny peanuts to some of these LIP flows.
        CAMP was many flows, but generaly most of them huge in scale. Many of these LIP flows forms 60 meters high sheets of hexagon columns that can be followed for 100 s of km in some cases, at least souch sheets are not slow pahoehoe.

      • In other words a huge sheet of Aa the size of UK thats slowly advancing towards you
        50 meters high walls of glowing moving rubble, at very slow walking speed. But on other minds – viewpoints, these mammoth columnar sheets coud be ponded lava seas near the fissures. Basalts from large LIPs emerge at high temperatures, and are likley very fluid, so Im supprised of the sheer thickness of some ancient LIP flow units. North Atlantic Igenous Province may have erupted at surface near 1400 C at paleocene Superplume phase, according to some papers that I read.

  17. Kilauea has started a normal DI event. It is behaving as if nothing has changed! The GPS appears to have stopped rising, after 5 cm inflation. Wait until after the DI event to see whether this is an interruption.

  18. Hvo is now displaying quakes in the area of the recent activity at Mauna Loa in the magnitude 1 and below.

    • This lava is clearly not as fluid and smooth as Hawaii or Erta Ale, probaly haves to do with lower temperature. It becomes Aa very quickly in this video already at the vent its rather like fast moving Aa. I wonder what similar vent at Nyiragongo woud look like upclose : )

      • Quite a big quake for where that is, inside a mantle plume…
        Maybe the magma behind the Pahala swarm is finally getting to Kilauea, in 1959 it was a few months between the deep quakes and the eruption, the pathway now is probably more open so there might not be many deep quakes but if more happen then next year is looking interesting.

        2021 will be the end of the drought 🙂

        • It’s lithosphere so there are probably some areas that are more rigid than others.

          There has also been a flurry of 6 deep earthquakes, 23-24 km deep under PUHI GPS station and another deep earthquake at Volcano Village. Perhaps they are related to the M3?

          Meanwhile the deep storage south of Kilauea keeps inflating rapidly, most stations of the Summit and Koae areas are being uplifted faster than ever since the sill intrusion of 2015. Even MANE may have started to reinflate for the first time since 2018. Pu’u’o’o could be returning to an inflation trend too.

          I’m not sure yet but it looks like the Pahala mantle surge has already arrived at Kilauea moving through a hot ductile area between them. However the shallow system is now deflating, perhaps it’s a big DI event, or not.

          • The shallow system deflating is maybe just from degassing, DI events were often associated with gas pistoning of the lava lake before 2018. I guess maybe the SO2 hasnt reached the surface yet, or the lake is scrubbing it, or the emissions are too diffuse to actually give an increase at a single location, or all of those things…

            Really it just means there isnt an open flow between the magma under Halemaumau and the main south caldera chamber. Is the east rift fed directly out of the south caldera chamber? It must at least be fairly deep, lava fountains on east rift vents are as powerful as summit eruptions and are not dependant on the elevation, Kapoho vs Mauna Ulu for example.

          • Pressure rises and falls syncronously in the East Rift Conduit and the Halema’uma’u reservoir while the South Caldera source does things its own way. That is why I think the ERZ Conduit must come from the deeper levels of the Halema’uma’u Revervoir.

            Considering that the rift collapsed in 1790 then the Halema’uma’u Reservoir must have collapsed down to those same levels (around 3 km deep) feeding the ERZ, I think some of the outermost ring faults of the summit caldera probably date to 1790, but the conventional view is that they formed in 1500. Now I believe that East Rift activity decreased after the drainings of 1650 and 1790 not because the ERZ Conduit itself collapsed (which it did, but only in a few spots) but due to the summit magma storage that directly fed the conduit being destroyed.

            The fountains of Halema’uma’u can also be very powerful, like the Golden Pumice…

          • I would guess there are probably multiple connections. I found the 2018 insar data and the deflation was most obvious south of the caldera even though it was Halemaumau that enlarged and saw a collapse. I dont know exactly but this pretty well shows that the rift at least sometimes is directly connected to the main chamber, if not all the time, and not just through Halemaumau.
            1959 eruption was also not from Halemaumau and preceded a rift eruption, the fissure in Kilauea Iki was aligned with the crater wall but the main vent was directly on the ring fault of the caldera as a whole, that with the rather extraordinary temperature and power of the fountaining along with unusually long (for a summit eruption) seismic precursor suggests it had its own connection to the main chamber though could have also been connected to Halemaumau. 1960 magma was in part the same very hot picritic basalt as at Kilauea Iki so seems to have been from a common source.

            I guess an easy fix to this is that there is actually no defined gap at all, that the Halemaumau chamber is just a molten pocket at the top and from that point down the rock is soft.

          • There is no defined difference between Halema’uma’u and the South Caldera Reservoir and each is not a single body either. By the way Kilauea collapses I personally believe that Halema’uma’u is made of several sill-like bodies that are around 100-200 meters thick each, and separated by crystal mush, all of the complex with the shape of a cone or a stepped pyramid.

            The ERZ conduit perhaps taps the deepest of these Halema’uma’u centred magma bodies, at a depth of around 3 kilometres and at the top of the deep rift. Anything deeper than this I simply call deep storage and seems to behave somewhat separate of the shallower parts, it is immersed in a dunite crystal mush, best known as the deep rift…So yes, I believe it is quite complex.

        • Obviously not where the mantle plume is. That stops deeper. This seems like close to the depth where the lava piles lie on the oceanic crust (depressed to this depth by the weight of the island).

  19. Looking at the shore of Toba’s caldera / lake, it bears an unsettling resemblance to parts of coastline further along archipelago. We know from other subduction zones that though ring-faulting and flank eruptions may create ‘volcanic groups’, ‘primary’ players are a wary distance apart. Must wonder if some of the Indonesian islands’ gaps began when a big eruption then caldera collapse opened a way from coast to coast.The area’s weather and strong currents may then clean up…

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