Taal in water

Long time no sea… 😀  For those of you not familiar with me, I am one of the “dragons” that lurk behind the scenes.  My main claim to fame is that “I plot stuff.”  I also on occasion have written filler articles when needed.    This isn’t one of those articles… but since I am a bit behind the workload in contributions, this was sort of assigned to me.  My primary goal is to write this without scaring the crap out of people but still convey the seriousness of the threat.

First, some background.  Water is a pretty unique fluid.  There are some conditions that water can be in that change the way it behaves.  Normal boiling point for water is 100 deg C.   Above this temperature is turns to vapor.    If it is a pot on the stove, it boils as it does so.  But take water up to a pressure of  22.064 MPa  and it gets weird.  This is a critical point of water.  Above this pressure, no matter how much heat you add, water will not turn to vapor.  That is about twice the pressure found in a 1200 psi steam plant on board a ship (before they were outdated by technology and gas turbines became the go-to technology for main propulsion systems)  The beauty of a steam plant is that pretty much any fuel was suitable as long as it made fire.  Vodka, Diesel, Aviation fuel etc.  (At one time the ship I was on was burning decertified aviation fuel to keep from wasting it.)  But this is not about Naval weirdness.

Throughout its history, Taal has been known to have base surge as a phenomenon in its eruptive style.  This was noted by a former physicist who recognized a similarity to a base surge in atomic blasts.  In atomic testing,  one curious phenomenon noted that the surface blast wave appeared to be traveling faster than the speed of sound.  This should be physically impossible.  Eventually they determined that the air ahead of the blast front was being compressed and this artificially raised the speed of sound.  In a volcano, a similar process can be in play with enough energy.  But rather than radiative heating, compression heating is doing the trick.  This is the origin of a base surge and typically shows up with volcanoes in a water environment.  A “water volcano”  as noted in a very early Volcano Café article.

In a backchannel discussion  (yes, we dragons kick ideas around in our spare time) this article was brought out for review.

A large hydrothermal reservoir beneath Taal Volcano (Philippines) revealed by magnetotelluric observations and its implications to the volcanic activity  Alanis et al

From the abstract: “This {3km x 3km x 3km} high resistivity anomaly is hypothesized to be a large hydrothermal reservoir, consisting of the aggregate of interconnected cracks in rigid and dense host rocks, which are filled with hydrothermal fluids coming from a magma batch below the reservoir.”

Blink, blink…  whoa.  A region of pre-mixed hydrothermal fluids within the cracks and crevices of the host rock?  That is not very good at all.  That means that Taal does not need a flank failure to get water in contact with magma.  It could very well bring up that hydrothermal fluid in conjunction with an eruption.  All it needs to do is to drop below the critical pressure before that “hydrothermal fluid” flashes to steam.

For a conduit system open to the surface, that is anything shallower than about 2.18 km.  (assuming a water density of 1030 kg/m³). Under rock, it is roughly 1 km.

The boiling temperature changes with pressure. The critical point is for water that is 374 C or hotter. If the water is not quite as hot, then it first becomes normal liquid as the pressure drops, and boils when the pressure drops further. This will now happen closer to the surface.

The water turning to steam causes the explosions. If this happens a kilometer down it will probably not reach the surface: the overlaying rock contains it. If it is a hundred meter down, then the rock above will be ejected. At the extreme this can form a volcanic maar, a circular fairly shallow crater which can be anything from a few meters to over a kilometer in diameter.

With such a large water reservoir underneath Taal, a lot of hot water can circulate up. The phreatic explosion a week ago means that the circulating water is getting hotter, and it reached boiling temperature a little below the surface.

My point is, Taal can be VERY dangerous as evidenced by its past performance.  It is IMPERATIVE that any warnings issues by PHILVOCS is heeded.  This volcano, along with other systems in the Philippines is their focus of study.   They ARE the experts.

Informal Q&A from another Dragon: Why does the steam plume take on a darker color as it goes into a sort of phreatomagmatic phase then return back to just steam?

As noted in Alanis et al, the hydrothermal area above the shallow magma reservoir is made up of many small fractures and cracks with water entrained within them.  As the steam is being released, occasionally some of the rock near the pathways break loose and are pulverized if they can not withstand the pressure of the superheated steam passing by.  Superheated steam can easily erode pathways.  Presumably, as the water above 22.064 MPa (3200.1 psi), so it could be at any temperature, just the act of moving into a lower pressure region allows it to flash to steam…. at 3200 psi or less.  (Main Steam on 70’s and 80’s era USN vessels was 1200 psi.)

Additionally, water in contact with magmatic rock probably acts to cause the rock to undergo serpentinization. This is a metamorphic change in the rock where water is taken up into the crystal lattice of the rock and form new minerals.  Generally this new mineral form is weaker than the original rock.  (Talc, Chrysotile, etc…)  I don’t know if this has much bearing on the issue of Taal, but those alterations can act to lower the melting point of rock as happens at the melt region 110 km deep on the subducting slab that feeds the system.

Some discussion has been made about Taal having a more mafic nature to its magma supply.  Granted, the He ratios support this, but don’t assume that it’s just going to be a sedate mafic eruption.  Not very far away is Mindoro island.  If you don’t remember, SleeperFish, an article from some time back, pointed out that Mindoro is the far eastern end of the Palawan Continental Terrane.  My opinion only… Mindoro is probably the result of continental crust not wanting to subduct.  As a rule, oceanic crust, being denser (≈3100 kg/m³), easily subducts under continental crust (≈2700 kg/m³).  None the less, shards of continental material could very well be in the melt pool that feed Taal.

“It’s like an intersection between two trenches”

Not according to the prevailing information.  Taal does fall at the intersection of two volcanic lineaments, but not trenches.  Taal’s closest active neighbor along those lines is actually Pinatubo.  Honestly, Pinatubo seems to have a more pure oceanic crust feeding its melt zone down at the 110km contour.    An archive quake plot of the region is available in the SleeperFish article.  There you can see the Benioff zone indicated by 37 years of mag 4.5+ quakes. The subducted plate dangles almost straight down underneath Taal.


Alanis et al




241 thoughts on “Taal in water

      • It’s an early sewage works in Yorkshire.
        “Where there’s muck there’s brass” says the bloke on the left to his potential investors.

      • RE:Jesper Sandberg commented on Taal in water, in response to ZZDoc:””Ever wonder at this classic photo?? “”

        ‘Halema’uma’u lava lake in Kilaūea’

        “Yah, for sure!! ” I posted this in response to a comment which essentially referenced being in the wrong place at the wrong time. For years,since the first I every saw that photo, and every time I see it, it boggles the mind as to how people could descend to the floor of Halema’uma’u and stand THERE!! One good ‘burp’ and they’re ‘cooked’…literally. This is T.A.Jaggar’s time and I don’t know that even he would have done so without justifiable scientific reason.

    • Looks like the ‘leak’ at the bottom of the cone sealed itself and all the lava is now flowing out of a side channel of the main top exit. If the seal is strong enough it’ll keep the pool a high levels and the eruption more episodic than the straight drain we saw with the flows from the bottom of the cone.

      I wonder how long it’ll go in this direction only? Meradalir certainly has enough room to accommodate the inflowing lava for quite a while before neighbouring valleys would get inundated. For now at least, the road, fibre optic cables, and coastal farm are not in imminent danger anymore….

  1. James Webb Telescope will be amazing!
    I think its Around 100 times stronger than Hubble! James Webb Telescope will be able to see the first galaxies when universe began forming stars at massive rates .. and perhaps pees back to even before galaxies was formed.

    JWT will totaly shatter hubbles extreme deep field view …. Its for launch in a few months this space telescope

  2. And the High Defenition Space Telescope will replace James Webb in 2030

    Coud HDST see the exoplanet around alpha centauri and resolve surface detail?

    • It’s great to think what these telescopes could see. But the reality may be rather different.

      Webb is to be lofted into space in October. The explosion from the launch vehicle as it rises through the atmosphere will be spectacular. Even if it reaches its destination, the thing has to deploy without being damaged by the spanner left in it by some muppet on a tea break. These are hideously complex pieces of kit and so much can (and will) go wrong.

      And HDST may be delayed to 2050, judging by the huge delays to the Webb. That’s before its launch vehicle achieves a perfect parabola and plunges into New York.

      Excuse me for feeling so negative about this. The ridiculous delays on the Webb have left me deeply frustrated, and that’s before I discovered loads of astronomers are booking time on it to look at Jupiter, Mars and Saturn. WTF? (Excuse my language.) Why waste time on this instrument on local stuff?

      On top of that, ground-based observation systems seem to be increasingly making the Webb redundant before it is sent into space on top of a giant firework. It takes little to cast these feelings forward to the HDST.

      If Webb is successful in deployment, few will be happier than I.
      But I just have a really bad feeling about it. 🙁

  3. Well, it appears that the Geldingadalir eruption is in a paused phase again. The flows out of the crater were episodic this morning until a last major episode peaking around 2021-07-18, 09:16, and ending by 09:22. The visible flow down the slope to the floor of Meradalir ended by 11:00. It will be interesting to see how long this pause will last.

  4. In watching the evolution of the growing lava field, see https://www.youtube.com/watch?v=pw0cpgmGHG0, I noticed that the video creator has access to current satellite maps. My google maps is stuck on stupid, still displaying the Geldingadalir area before the fissure eruption even started. Does anyone have a link with current satellite data for the fissure eruption area?

    Thank you.

    • One of a handful of times when the music soundtrack doesn’t detract from the visual content.

    • According to the video posted by 67doug (18/07/2021 at 13:48) – see above – I think that’s the exit point for the lava to leave the lava pond in the cone. The bright ‘lava fall’ to the right is where that channel starts to empty towards Meradalir.

    • I believe that is the exit point, but only seen when the lava level is high in the active cone. We need several drones up there taking pictures and posted, to see what is really going on.

  5. Its certainly being quite productive. There are fountains, perhaps as high as earlier given the larger size of the edifice, but not just squirts, really wide gushers.

  6. On this video, a guy on lake Taal just kicked some pumice from the shore into the water. He also threw one to show that it floated. I heard in chat yesterday there was pumice; this has video evidence.

    • Yes.

      That one gave me all kinds of “get me out of here, NOW” vibes. Happy to have the whole distance of the ‘net between me and that.

  7. I’d like to go back, @ Albert and Ellen, to your discussion about a place in NYS and about the Netherlands and building on flood plains.
    Take a look at a Sat map of Erftstadt-Blessem. What you get is a field with not enough solid ground and earth a little above buildings, homes and a horse stable and next to it an enormous hole where they dig or dug out gravel for building purposes. This is the wrong combination to start with, but in the end there’s no culprit except the long term climate.
    This sort of building and constructing, also in flood plains, happens easily with a little bit of money, offers that nobody can refuse. The same with river deviation.
    This is also known for the whole Spanish and Portuguese coasts, and arson is made by the wind.
    We have to refuse the Climate legend as an excuse in every single case as its is also very comfortable to cover all forms of corruption. Instead we need transparency.

    • To be honest extreme floods and weather have happened for centuries. Whether your house is destroyed once a century or twice a century isn’t really much of importance.
      In hilly areas where all the houses are on the valley bottom in the floodplain, because that’s the level bit, do not be surprised if you are seriously flooded out from time to time.
      As with areas where there is fire risk its best to take appropriate remedial action in advance. For example:
      1) Have your electricity come in at first floor+ level and put your trips there (higher is better) and arrange it so floors can be electrically isolated individually.
      2) Use waterproof plaster on walls (use google) and if possible water-damage-proof flooring (eg tiles).
      3) Very high risk areas have roof access and even a small inflatable boat.
      4) In the UK it was usual to have water tanks in the roof for hot water and heating, which did provide some cleanish water.
      5) A small gas heater and a few tins of food in the attic would not break the bank, either.

      But like my neighbours who moan when I have electricity during the odd power cut but never bother to buy their own cheap generator (now about £200, but you used to be able to buy two stroke ones for £50 on offer), nobody does.

      Much of the blame goes to planning authorities who give in to planning, indeed encourage it, where they should not.

  8. Someone is buzzing the Volcano with a King Air. Sadly, it does not seem to be for new photogrammetry, they are flying way too low for that.

    Right now the cloud cover would actually allow for new measurement flights, but no aircraft for that is around, apparently not available. Flying in Iceland must be hard, weather wise – wait wait wait fly! wait wait wait:-)

    • Was just noticing the fine weather today, on-camera at least, for the Geldingadalir/Meradalir valley area. So unusual.

  9. Anyone know the location of the “Litlihals – Natthagi” camera on ruv? I know where Natthagi is (approx), but can’t find Litlihals on the map.

    And what was the digger doing there today?

    • It looked like it was preparing a site for some building work. A 5G transmitter, perhaps? This is a blind guess, of course

    • Litlihals is the flatter area south of Natthagi and Borgarfjall. On the maps I have looked at, the label tends to show on the stretch of the coast road that goes North/South.

  10. If I am not mistaken this is some nice tremor,

    If I am wrong feel free to call it out.

  11. Has the tooth stopped its bobbing about, and settled back down? It hasn’t been mentioned recently.

    We are approaching the sparkling hour too, hopefully we will see a bit of scintillation soon if the suns stays out.

    Just had a thunderstorm graze by, the rain has cooled us down a bit from 29 degrees.

    • Been warm here too, but I omitted to check the external temp until I read your post.

      Currently 29C in the shade at 7.00pm, no wonder I thought it quite warm, particularly in the sun.

      • Temperature here touched 30C for the 3rd day running, and even now it is still 25. Manchester-not-by-the-sea has become Manchester-in-the-tropics. Of course with our covid epidemic among the young people, all of whom still live at home, half the town is in isolation. The lifting of restrictions on the other half should mean that soon the entire town will be stuck at home.

    • I spotted that storm on the rain radar. You couldn’t sent it back around our way please? 🙂

    • I don’t know what the exact temperature has been here, but pretty similar, nothing to cool it down though.

  12. The surface crust of the Meradalir lake keeps being pushed up from below by at least a foot or two every day.
    About two hours ago (17:00 local) the region close to the Meradalir cam
    started to rise even faster; I noticed because just now (15 minutes ago, around 19:00 local) liquid lava started oozing out from underneath the rising lid right in front of the camera (bottom left corner of the video, of the Meradalir #2 cam view). Fun to watch…

  13. Gasses/fog from the eruption were meassured here in the Faroes yesterday, don’t know if it’s the first time for this eruption, but it’s the first time I read about it.

  14. Another pause after a major outburst between 17:34 and 17:35 today, 2021-07-19.

  15. Getting hyped for Taal, yesterdays tremor was so strong that it was felt on the surface and was accompanied by rumbling noise!!

      • Thank you for your continuing set of reports on Taal, which I read with interest.
        Please keep it up.
        Iceland is not the only place, although it manages to be unusually photogenic and complex.
        Taal will be nothing much until it abruptly becomes a Really Big Deal.

        • And the pathetic part about the RBD aspect. EVERYONE knows what it can do. When it happens, there will be the inevitable lamentation of how come we weren’t warned?

          You can’t even make a good black swan argument. It doesn’t have a low enough probability to be ignored.

          • Does Taal have the possibility of being a climate affecting eruption when it eventually erupts, in the way that Pinatubo was?

  16. GPS stations at Kilauea are showing the same sorts of signals as immediately before the eruption last December. CRIM and OUTL are accelerating up, and OUTL also now strongly west, both actually has now far surpassed the values from December. There are also some swarms of quakes along the magma conduits. Still no continuous swarms along the whole thing like last year but that might not happen every time, and we know how suddenly eruptions happen here now, its a matter of an hour or less of warning.

    I have some feeling that the next eruption is going to be bigger than the one in December, and could be more extensive with the deep pit filled in part way, fissures not only in Halemaumau but also the caldera floor and/or ring fault. Pu’u O’o output was 3x the volume of the December eruption annually, there is catching up to do.

  17. Fagradalsfjall is trying to be mini Etna right now, lots of lava flowing down the hill. It is becoming episodic, a lot of sources say this means it will end soon but I think it is just the beginning. There is a direct open hole to the mantle, that is very hard to kill, if the eruption was going to stop so easily it would have 2 weeks ago…

    Really the scale of the eruption is unbelievable compared to how it all began, its gone from a volcano that is almost comically small to something we can call a mountain in its own right. I do wonder when it will recieve its own official name, the lava field has but the cone is still unnamed.

    • It’s been episodic since May, so whether it’s ending soon depends on the definition of “soon”, I suppose.

      I reckon it will go on until Christmas, at least, but I suppose no matter how long it will still be soon, geologically speaking 🙂

    • I like the new Meradalir cameras. They give a good view of where the lava is going (at least for now, until it goes to Natthagi again). Theatre hill is becoming a bit one-sided. At some point lava is going to come over the top

      • Yes probably in a month or so this side of the cone will also be a shield and elevayed high up, and then it will encourage lava to break out into Geldingadalir. It will flow into Natthagi quite rapidly from there, and probably from multiple directions too. Will really test the walls. Then same thing again, and the cone progressively builds itself up on the top as it goes.

        Would not really surprise me if these Icelandic shields are actually fountaining spatter cones when active, the cone creating a sort of shallow magma body under itself that it falls into post eruption.

      • “Theatre hill is becoming a bit one-sided”

        I wonder if that’s why the visir cam is stopped at 23.10 on July 14? I always thought it was a bit low down.

        • That is a good point. I had not considered it but it was quite low above the flow. The acid gasses may have killed it before any lava had the chance though. Volcanism and electronics is an uneasy combination

      • Can we see Theatre Hill on the close Meradadalir webcam?
        Or do you mean Communications Hill?

      • RE:”Theatre hill is becoming a bit one-sided. At some point lava is going to come over the top ”
        At 9:47 a.m. EDT 7/20/21 the weather out there is wretched as are the fools in front of the RUV camera viewing from Langihryggur. All the drone fliers want to drive up the outflow, peer into the vent and watch the pot boil. At this point in the evolution of the shield, a good, comprehensive aerial view would be of great interest. I’d like to see how the cone is integrating into the slopes.

    • The lava-free peninsula opposite the Meradalir cam has disappeared this morning, under a thick layer of lava. Lava has also now mostly covered the rock group at the upper end of the late peninsula. I think that is significant in the sense that the top of those rocks should be at approximately the same elevation as the lowest outflow point of the meradalir valley to the east (unfortunately outside the field of view of the camera).

      Of course there’ll be a bit of a downwards slope of the field surface towards that far end of the valley, but not that much, since the lake clearly is still liquid underneath. So the level should come quite close now to overflowing (at least the top level – the rising crust will have be elevated a few feet above the overflow elevation to actually start a flow out from underneath it).

  18. They actually did tilt the Meradalir Zoom camera south once yesterday, with a zoom to the far end of the south-east branch of Meradalir.

    According to the 3D model, the top of that half-buried rock formation (different one from the one mentioned before) in the center is not more than one or two meters below the outflow elevation.
    (but this point is several hundred meters downslope from the outflow point)

  19. Over the past four days, roughly 4 million m^3 has accumulated in Meradalir. The exit is less than 5 meters away. There has been enormous accumulation along the path to Meradalir, up to 10 m in many places, perhaps another 2 million m^3. The Visir hill is 2/3rds of the way buried. The average flow is 15-20 m^3/s.

    The attached image shows the new areas covered in Meradalir since the last flyover, fairly small considering the increase in depth. https://imgur.com/a/gdByArO

    There have been extended periods of high and low flow in the past few weeks, including a 3-day pause two weeks ago. The flows during the past 15 days have been 12+ million m^3, so the rate appears to be steady. Same as since early May, the eruption pattern periodically changes, but the volume does not.

  20. The above ground lava all flows into Meradalir. Not so sure about the lava below the surface. Note the smoke vent on the far right. Where there is smoke there is something causing it. I don’t quite have enough bearings to see whether this is the old but rather elevated geldingadalir

    • It looks like it is to the north of the old vent 2 cone, and quite possibly on the extension of the fissure line.
      Whether it is steam or volcanic, it indicates there is heat and magma near the surface.

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