Taal Update – Ongoing Intrusion

Guest post from Héctor (DustDevil). There will be a further update either later today or tomorrow as events have changed since Héctor wrote this post.

The Main Crater of Taal seems to have calmed down, doesn’t it? However fissures are breaking the ground apart, the river dries, Lake Taal falls and strong earthquakes keep coming. What exactly is going on right now at Taal behind all of these changes?

As I have mentioned a couple of times in the commentary section of the previous post a dyke intrusion seems to be occurring. This is not something you are going to see in the news, at least not the word “dyke”, and at least so far. However, for someone with a particular and deep interest in the workings of rift zones and basaltic volcanoes (like me) what was happening seems obvious.

And don’t let the enormous caldera of Taal fool you, it is a basaltic volcano after all! Might have done a couple of large silicic eruptions in the past with ignimbrites but currently, it has more in common with a shield volcano.

The Macolod Corridor

To understand Taal knowing about the setting is necessary.

Taal is located in the Macolod Corridor, an area varied volcanism, basalts, andesites and dacites are found here. It spans a 60 km long area of southern Luzon, Philippines. Even though small in area there is a number of volcanoes, you find 2 large calderas, Laguna de Bay and Taal plus a number of stratovolcanoes (Banahaw, Makelunyo, Makiling) and monogenetic vents: maars, cones and domes.

https://i0.wp.com/www.volcanocafe.org/wp-content/uploads/2019/10/pi-post.png?resize=460%2C337&ssl=1

If you want to know more things about the setting you can head to this previous article by GeoLurking (and source of the map): https://www.volcanocafe.org/sleeper-fish-a-look-at-the-taal-and-laguna-de-bay-setting/

The secret to the productivity of this region is rifting, you can think of it as a small continental rift. The rifting nature of the Macolod Corridor is well agreed upon, but how this affects Taal and its eruptive history has never really been considered.

A rift volcano

Taal works with dykes, these happen when magma forces open a crack and flows into it, the pressure of the magma and volatiles keeps expanding the crack and so on as long as conditions are right. It turns into a fiery sword slicing through the ground. When it touches the surface, magma comes out though this won’t always happen.

Iceland has an important place in this blog so you are probably already familiar with how important this is in a rift, dykes fill the space opened by the separating tectonic plates.

In Taal it is similar, major events such as the eruptions in 1749 and 1911 included large cracks opening up parallel to the Macolod Corridor and areas of the ground subsiding. This is what concerns most right now because it is what is currently taking place.

The 1749 and 1911 were devastating and if you want to know more about their deadly effects, once again this article by Henrik contains a lot of information on them: http://www.volcanocafe.org/the-tiger-in-the-smoke-taal-the-new-decade-volcano-program-8/

When a volcano intrudes a dyke but it stays deep below the surface, the ground above is pulled apart, it snaps. You get a graben and cracks open which is what happened in 1749, 1911 and now.

Photograph of fractures and subsidence that occurred in a flour mixture when a simulated dike was forcibly widened (dark area, bottom), similar to cracking that occurs at the surface above intruding m

An experiment showing how ground cracking takes place due to the intrusion of magma. The black material at the bottom would represent the dyke. From USGS, Mastin, L.G., and Pollard, D.D., 1988, Surface deformation and shallow dyke intrusion processes at Inyo Craters, Long Valley, California: Journal of Geophysical Research, v. 93, no. B11, pp. 13,221-13,235.

As magma drains away from the magma chamber and into the dyke, the caldera subsides, water flows into the new volume lowering Lake Taal’s water level, it is possible that is the main cause why river Pansipit is currently drying up. However, deformation from the dyke and ash blockage is also to consider which have also been proposed by fellow readers.

Current situation and the future

PHIVOLCS currently maintains Taal at alert level 4 and reports that new cracks keep opening. These seem to be located to the southwest of Taal Lake, coincident with the area of earthquake epicentres. As previously mentioned the earthquake swarm and ground cracking is very likely the result of a dyke intrusion.

The situation plays by the rules of basaltic volcanoes, and don’t get me wrong, rhyolite dykes (and of other magmas) do exist but they are not as frequent. The dyke (usually) starts to intrude under the summit of the volcano, same goes for Taal, this phase involved a subplinian eruption from the Main Crater of Taal and lava fountains on the north flank of volcano island, this happened through the afternoon of January 12, with the lateral vents opening the 13th. Hard to say exactly when (future scientific analysis will have to constrain this) the dyke intrusion propagated to the southwest from the summit to outside the caldera.

PHIVOLCS still warns of a POSSIBLE hazardous eruption. So let’s consider what possible scenarios could lead to another violent eruption:

– Vents open along the dyke: Taal doesn’t seem to erupt outside the Caldera, which is good news to the local population. Bad news is that fissure eruptions are a bit unpredictable and that new or previous vents in the Volcano Island area can open or reactivate, even if unlikely.

– Caldera faults rupture: When magma leaves into a dyke intrusion you drain the magma chamber of a volcano and it can reach the point of collapsing. From a tectonic viewpoint, this happens when the caldera/ring faults give way to the strain they are under, and this is quite sudden! Remember the collapse events of Kilauea? The Talisay (Taal) Caldera is unlikely to undergo major collapse, but the Main Crater in Volcano Island is a smaller caldera structure and more vulnerable.

If this happens we are in uncharted territory but one can picture water making its way to the magma via collapse. Worst case? Probably a VEI 4.

However, it is also likely that dyke intrusion will eventually stop without any these scenarios taking place. The earthquake swarms have slowed down over the last 2 days which could be a sign of the intrusion coming to an end, but since there are ways the situation can escalate again anyone violating the evacuation ordered by PHIVOLCS are putting themselves under grave hazard and in case a paroxysm occurs there is no telling how much time people will have to run, and it may not be enough.

Following Lurking’s advice, do not be there!

Héctor

294 thoughts on “Taal Update – Ongoing Intrusion

  1. The authorities have now stepped up evacuating the danger areas, with more manpower to make sure everybody leaves.

  2. Thank you for the update DD!
    As mentioned above there will be another update either later this evening, or tomorrow, due to how rapidly the eruption is evolving.

  3. Let’s not forget the interferogram SteveR posted in a comment on the previous article.

    I believe the source is from this twitter account: https://twitter.com/manabu0131dpri

    There is no scale attached to tell what the fringes mean, but comparing with other interferograms using the same color scheme it seems like there is inflation in the southern part of the lake and deflation in the north and west. This means the lake is tilted away from the river and explains why the river has gone dry.

    Roughly speaking, inflation around the earthquakes and deflation around the main crater. Is this the correct analysis?

    • The general inflation to the north is 50cm and counting.
      I think the drying out is more likely to be caused by the river bed rising up damming the river.

      There is local deflation due to the eruption, but the entire shebang as a whole is inflating.

      • There a “butterfly pattern” south and west of Taal, which is what I think geolophysicists call it. That seems coincident with my interpretation of a dike intruding south-southwest of the lake with one side moving towards the satellite and the other away.

        Combined with the other evidence (the area of fracturing and the swarm) I would take this as a confirmation of the dike intrusion. Which is relieving since it was initially speculative

        • There, I painted (roughly) the likely dike path (red). It appears to be similar to the 1911 intrusion, perhaps smaller since back then 3 m high scarps opened up and it doesn’t seem it has gotten to that this time.

          Lack of much information on older historical eruptions led PHIVOLCS and everyone to draw comparisons with 1911, but expecting a perfect repeat was of course too idealistic.

          • I’m curious. Why would the dike path be in the area that isn’t showing any change in ground elevation? Why isn’t it in an area that is rising?

          • The black area is missing data, Albert can probably explain better, but it may be largely due to the ashfall which doesn’t do well with interferograms. Some surfaces are not adequate for the technique and I am not sure if the intense ground cracking above the dike may also pose a problem.

            Also note that just above the dike the ground is expected to subside not inflate. The surface moves in opposite ways so the central part drops. That seems to have largely the issue these past few says with the opening cracks.

            It is not a coincidence that river Pansipit follows the Macolod Corridor, it is a graben.

            A map with the cracks would help but that isn’t avaliable right now I far as I know.

          • I would like to ask three questions:

            1. Would this dyke have a kind of axial start/end?

            2. Would this dyke flow from the center of the volcano to somewhere or is it the way for the magma to the volcano center?

            3. This strong earthquake swarm today close to Mabini was sign that the dyke already progress there in the sea (or opposite direction depending on Q2)?

            https://twitter.com/jamzkiekie/status/1218922413880012802?s=19

          • All of this started with a phreatomagmatic eruption from the Main Crater, this is basically showing that the dyke initiated from the summit/head of Taal’s system, as it rose it encountered water which flashed to steam, with the eruption then following.

            Later the dyke would have propagated away from Taal meaning lava was drained from the magma chambers into the rift which is the way these events go.

            The earthquakes in Mabini are probably just a fault rupturing, the intruded magma changes the stress field in the area so that some nearby faults may still be settling even if the intrusion is over. Can the dyke intrusion restart again? There is a low chance but it is unlikely. There have been eruptions elsewhere in which several dykes are intruded episodically during a rifting event, but that is rare.

      • There are three lobes with color fringes in the picture. In the two upper ones the fringes cycle through the colors in the opposite way from the lower one. One way is inflation, the other deflation. I can’t tell which is which, but from your comment it sounds like I got it the wrong way around.

        If the entire shebang is still inflating, despite the eruption already in progress, that’s probably not a good thing.

        • You can’t really know if something is going up or down from a interferogram (it can be up or west), you know if it moves away or towards the satellite and you can take a guess.

          The fringes are a bit confusing to me as well, north of the lake I think would be away from the satellite, the south lobe would be towards and the west lobe away, correct me if Im wrong.

          • They should just make it blue and red. I am not sure why they complicate things so much, it is almost as if they wanted to turn the image into a puzzle on purpose.

          • Good point, changes in distance to satellite does not necessarily mean changes up/down.

        • looks (to my amateur eyes to have one ‘centre of the ripples’ just to the east of something labeled calaca on that map – and the butterfly looks to be around a line heading pretty much EastSouthEast

    • [Edit Lugh: if you use the ’embed’ function hidden at the right top, a tweet shows in your comment]

  4. Accidentally posted on the old article, so repeating here. The following video was made / posted on the 3rd Jan, and gives an indication of what the area looked like prior to the eruption – a couple going on a trek to the caldera lake. You may find some aspects of it interesting to watch, and it seems to me there are definite clues that indicate increased activity, although I have no comparison from the past. Anyway; (possible?) warning signs of increased activity. https://www.youtube.com/watch?v=U8AvkiJQK8E 15 minutes long.

  5. Here is the radar image before the explosion

    And after (yesterday)

    The dark blue means that the radar signal was poorly reflected, i.e. thick ash/tephra cover. (This area is therefore also missing from the interferometric image). The lake is indeed largely gone.

    • I’d say there’s a rather large area affected by ash/tephra on the interferogram, roughly the whole area that suffered ashfall. That makes a more precise reading for the danger zone harder? Also because Phivolc’s measuring equipment is mainly in that area. How is such equipment affected by ash fall?

      Picture comes from this article on temblor.net.

    • A very clear radar plus satellite images posted in this BBC news story.

      https://www.bbc.co.uk/news/science-environment-44661949

      Ties in with the twitter footage shot be the two insane locals that yomped up to the rim. A shattered looking landscape instead of the lake bed, suspect in part due to older craters being exposed by the loos of water. Looking at Alberts posted images, Vulcan point island looks to still be in situ and is i think roughly where the arrow head is on the longer arrow shown in the BBC radar image.

      • Just to add, the orientation of that blue radar image in the bbc story appears to be looking from west (bottom of image) to east (top) although, slightly south of west may be a better description.

        That would put the hot spot in the image that Albert posted the other day almost dead centre of the image. Also ties in with the footage of increasing hydro-thermal activity just proceeding the eruption. The webcam would have been between 11/12 o’clock on the image, halfway between the dashed outline of the the old lake shore and the crater rim.

    • Am I correct? Radar info is missing as a result of diffuse reflection caused by the ash, whereas the interferometric image lacks info because of specular refections (water)?

  6. This one is easier to read

    The arrows indicate the assumed expansion (inflation) which causes the ground to move away from the centre. The satellite was (I believe) a bit to the east-southeast. Regions south or east are therefore seen to move towards the satellite, while regions west and north are moving away. (Actually, it could also be just the reverse with the satellite to the west-northwest.) The magma should be about 10km deep (judging from the earthquakes). For areas more than 20 km from the centre, the motion will be mostly horizontal. Closer to the centre will show vertical motion as well: this shows up on the western side where if you look very hard, the colour sequence reverses for the innermost contours. You don’t see that on the eastern side, which makes it more likely that was the direction of the satellite.

  7. Looking at how low seismic activity has been today I get the feeling that rifting is mostly over, even if some faults keep settling.

    I wouldn’t lower the guard just yet but chances of the caldera rupturing or new vents opening seem increasingly unlikely.

  8. Big problem with trying to guess what will happen next with this type of event is the timescale, build up to minor events could take months or even years and significant events decades and major events centuries and catastrophic events millenia. This thing could take what appears to be a respite only to start up again in a few months or a few years, or it could suddenly spiral into a chain of events leading to a larger event, more than likely it is an ongoing process that will have long periods of apparent quiescence. My opinion is these systems are generally quite stable and need an accident of nature such as a large earthquake to set them into a chain of instability.

    • By system I mean these caldera like structures often filled with a lake of covered with glacial ice.

    • Worth recalling what PHIVOLCS said in December. And will the quake level settle down back below the rate seen since last March or remain elevated?

      TAAL VOLCANO ADVISORY 01 DECEMBER 2019 08:00 AM

      This is to notify the public and concerned authorities on the current activity of Taal Volcano.

      Since raising the alert level of Taal Volcano to Alert Level 1 last March 28, 2019, the Taal Volcano seismic network has recorded 4857 volcanic earthquakes as of today (December 1, 2019). Some of these earthquakes were felt with intensity ranging from Intensity I (Scarcely Perceptible) to Intensity III (Weak Shaking) in Brgy. Banyaga, Agoncillo; Brgy. Calauit, Balete; Sitio Tibag, Brgy. Pira-Piraso, Sitio Tuuran, Brgy. Tabla, and Brgy. Buco, Talisay; and Brgy. Alas-as and Brgy. Pulangbato, San Nicolas, Batangas. Often, these felt earthquakes were accompanied by rumbling sounds. Precise leveling (PL) measurements on Taal Volcano Island from November 21 – 29, 2019 showed further inflation of the volcano edifice, consistent with the recent results from continuous GPS data. An increase in Carbon Dioxide (CO2) emission is also observed inside the Main Crater starting around April of 2019. However, there are no significant changes in the water temperature and acidity of the Main Crater Lake.

      Alert Level 1 remains in effect over Taal Volcano. This means that hazardous eruption is not imminent. However, there is a possibility of magmatic disturbance ongoing under the volcano. In the event of further increase in number of volcanic earthquakes, higher concentration of gases, continuous inflation of the volcano’s edifice, increase in water temperature and/or occurrence of widespread bubbling at the lake of the Main Crater, Taal Volcano’s status will be raised to Alert Level 2.

    • I couldn’t agree more and I have 2 things to add.

      Even when assuming that levels return to normal in a few days we may be entering a new cycle of eruptions. 1749 and 1754 happened in close succesion and were both major events, as such another hazardous event could happen in the near future.

      Second is that the northeastern part of the Macolod Corridor doesn’t seem to have rifted since 1749, this opens a window for another large event would it snap in a future eruption. The reason why the dyke chose to go SW while the NE area should have accumulated more strain by now is a mystery to me, and so I guess there are still a lot of thing we don’t know.

    • From accounts I’ve read this was the pattern also in 1911; spasms of increasingly violent activity separated by periods of complete quiet. Eruptions are chaotic systems, they don’t repeat themserlves exactly, but they sure rhyme, as someone once said about history

    • If that happens, all bets are off. It will depend on how confined the resulting pressure is and whether it can outgas without breaking rock. The flash to steam expands on the order of 1700 times the volume.

    • Thanks! that is really good one. It is also letting us know the satellite looks from the east.

      They may be more than one interpretation possible but here goes mine: The dyke seems to be pushing the blue area towards the satellite while the red area west of Taal is pushed away from it, and may also be moving up. The northeast coast of the lake is moving away too (red), it must be due to deflation of the magma chamber, if Taal was inflating it would be blue.

      • I am not an expert at all, but I am reading this figure the other way around: “LOS” is of course line of sight (to the satellite). Blue means this length increased, thus blue is DEflation, and red inflation…

        • Would make sense too. I had interpreted positive as displacement towards satellite and negative the other way, it seemed logic particularly after concluding the same with the first one posted here.

          I am no expert either so if someone with more knowledgeable on the InSAR technique can clarify it would be helpfull.

        • From comparing with other interferograms it looks like negative (red in this one) tends to be used for an increase in distance which would usually mean deflation. But still could use an expert here.

          • Would definitely make sense seeing that the LOS velocity is a Doppler measurement (redshift –> moving away). But I am as said not sure that this is the way the colors are used here.

            Eyeballing with this map here:

            Red is where the earthquakes are, whatever that may imply…

          • NO, it does not measure a doppler velocity. It measures a distance to the satellite, and compares that distance between two dates. It is complicate because the satellite is not in the same place for each measurement, and you get only the displacement towards the satellite, not the other two components. Horizontal and vertical displacement can’t be disentangled unless there are more measurements. In fact there was another measurement taken on Jan 11, so perhaps that can be used to improve the numbers. It is not possible to decide whether positive numbers are towards the satellite or away. You would normally take the numbers such that ‘up’ is positive but you can do it the other way around. The map makes a lot more sense if what we are seeing is inflation. The one place you might expect deflation is at the location of the explosion, where the number is indeed negative. But it could easily be the other way around. Numbers mean nothing without clear definitions.

            BTW, you did not say it measured velocity, just that the colour was normally used for such velocities. But it could have been understood as such.

          • You are right, but there it is defined as the terrain height variation in the Line Of Sight direction. So positive is up, or any other direction towards the satellite. As the satellite is east, the pattern is (mostly) that of expansion & inflation.

            Problem solved.

            I think.

          • Interesting, will read through later. But if that is right means the blue and red areas are converging which I find strange.

          • I have seen 2 interferograms of Ambrym covering the same event, one uses negative as distance reduction while the other as distance increase. So there doesn’t seem to be a universal rule, I am not sure if asking the creator of the plot is an option here…

          • DustDevil, seems so. As said, I am not a geophysicist at all, actually I am an astronomer. So in my world it is easy. Red = stuff is moving away from me 😉

            Here, I am simply not sure. Maybe one of you guys can simply take the interferograms and make a plot where we then know which is which? 😀

          • Albert, as said, my frame of reference simply is that we always use red for “moving away” in astronomy. I am in the clear that the “velocity” here is not an instantaneous physical velocity measured during the pass. That is not the problem I have. The problem I have is that it is needlessly complicated because the plots are not clearly labelled, which is a pity.

            You say it makes much more sense if we are seeing inflation. Whatever the interpretation of the colours and the +/- is, we are seeing both, right? So, what would you say is the blue color? Inflation or deflation?

          • The crucial question! And I agree that the lack of clear labelling is a problem. The satellite was to the east-southeast, perhaps 60 degrees above the horizon. I assume the vectors are radially pointing away from a centre, and also have an ‘up’ component. Close to the centre ‘up’ will be be dominant, far away it will mainly be radial. If magma rises, it can also give rise to a mexican hat pattern, where further out the ground begins to sink again as it is bypassed by the magma. The blue is velocity vectors pointing east(-ish) and/or up. The red is westward and up. Movement north or south was not detectable.

            In astronomy a ‘red’ velocity is positive. In other sciences that may not always be the case!

            The funny thing is that this would put the centre somewhere in the blue area, i.e. not on volcano island but in the southern part of the lake. It also does not explain the strong red east of Taal. That suggest more than one centre of inflation, or some deflation in the north of Taal, or a dike feature which however would have to be in the blue area.

          • But if red is towards the satellite, then of course the inflation is centred much further north..

      • Not an expert either….

        Stands out the caldera is split in two in this interferogram, about along the line of the Sibuyan branch of the Phillipine System fault as drawn in the map I posted bit above.

        The S b. was recognized by interpretation of seismic and aeromagnetic data in Bischke et al., 1990.
        The fault is active but hardly visible at the earths surface because of ‘fresh’ volcanic deposits.
        https://www.academia.edu/7967134/A_new_branch_of_the_Philippine_fault_system_as_observed_from_aeromagnetic_and_seismic_data

        • The 2 areas of opposing colour, or butterfly or spliting… when it comes to magma deformation the source is a dyke. If the source is a sill or a mogi source (modelled as a point) there would be just one area of the same colour. It can of course be more complex if there are multiple sources, which is usually the case.

          I assume that the deformation is caused by a magma body and not a fault. The earthquake swarm has followed a volcano-tectonic distribution which is tipical of magma intrusion as opposed to mainshock-aftershock distribution which would be expected if a major fault had ruptured.

          • With all regards Dd, I am still not convinced of a dyke forming, but maybe there is. Intrusion yes. Volcanic activity can be related to / activated by crustal movement.
            Did Taal dykes before? I spend hours looking for maps and articles about Taal’s history, but couldn’t find much. Are there any known signs of past activity outside the caldera coming from Taal?

          • Also something that I am not sure if other people have noticed but initial statements made by PHIVOLCS were as speculative as mine, PHIVOLCS doesn’t seem to have had a working network to monitor deformation if we trust the news they were also waiting for satellite based data…

          • They have talked about inflation before. But the insar data only became available this morning, and processing takes a few hours (on a machine with a lot of memory) and is not available out-of-the-box. It is a manual task that takes time.

          • Ref SAR data. Dead on accurate. The military uses technologically similar gear, but the processing is specialized for other purposes. Aircraft SAR uses snapshots of the target area compared to previous imagery. Naturally this entails phenomenally huge quantities of phase data that has to be processed.

          • Dd: “PHIVOLCS were as speculative as mine, PHIVOLCS doesn’t seem to have had a working network to monitor deformation…”

            PHILVOCS has another issue to deal with that many don’t concider; Equipment that tends to wander off.

            It’s a threat that a lot of long time monitoring gear faces.

  9. Okay looking back at Kilauea stuff, towards satellite was always red but the scale said positive was towards satellite. So as far as I can see red always means towards satellite.

    • http://pgf.soest.hawaii.edu/Kilauea_insar/

      For ascending maps, red colors (positive) indicate motion toward the satellite (up or west) and blue colors (negative) indicate motion away from the satellite (down or east). For descending maps, red colors (positive) indicate motion again toward the satellite but now up or east, and blue colors (negative) indicate motion down or west. The right figures display a wrapped interferogram map, where each fringe represents 2.8 cm of ground displacement toward (or away) from the satellite.

    • Blue is towards the satellite, the interfegrogram of Taal is a descending track (arrow of the track points south). Thanks Squonk! Took me a while to figure that up, the fact that if it is descending or ascending reverses the colour scheme…

      So I am not going back on my interpretation.

      I really hope some admin eventuallly makes a post on interferograms, if not I will. This really deserves a good explanation once and for all xd.

      • It doesn’t reverse towards and away from just east and west

        For descending maps, red colors (positive) indicate motion again toward the satellite but now up or east, and blue colors (negative) indicate motion down or west.

        • As far as I can tell the track is descending so yes then seems I was wrong in reading the map. Hope a model for the deformation comes up soon.

  10. This from the last PHIVOLCS press conference

    https://www.cnnphilippines.com/news/2020/1/16/Taal-Volcano-eruption-alert-level.html

    Phivolcs director Renato Solidum said in a press briefing later in the day that volcanologists would usually observe for two weeks to see if there is a downtrend in volcanic activity before deciding whether to lower the alert level.

    Bornas said it’s typical for a volcano to enter a lull during a prolonged eruption, adding it doesn’t mean a hazardous eruption is no longer possible. Alert Level 4 remains pending Phivolcs’ decision, she added.

    “Hindi namin sinasabi na ibababa na … May nasusukat pa tayong mataas na sulfur dioxide, mayroon pa tayong earthquakes, may fissures tayo na na-develop at namaga ‘yung bulkan. So nandiyan pa rin ‘yung potential for an explosive eruption,” she said.

    [Translation: We’re not saying that we will lower it … We’re still measuring high levels of sulfur dioxide, we’re still having earthquakes, new fissures are developing and the volcano is swollen. So the potential for an explosive eruption is still there.]

    Despite the volcano’s calmer exterior, the Phivolcs official warned there is potentially dangerous activity underneath Taal. She said there are fewer volcanic earthquakes but its intensities remain strong. The volcano also continues to emit high amounts of sulfur dioxide. These signal there is movement of magma or molten rocks underneath.

    And this a Google translation of other remarks attributed to PHIVOLCS at the press conference

    https://twitter.com/ABSCBNNews/status/1217623086716968960

    These seismic activities, the quake, the dredging of the other day and the retreat of lake water and the drying up of the river brook we interpret the widespread uplift of

    This suggests that there is still a volcanic magma beneath the volcano. We still have some danger. May be strong volcanic eruption.

  11. Where is the problem ? on the south side the ground has dropped by up to 50 cm *, on the north-west side, however, has gone up by more than 40 cm. So really asymmetrical deformation.

  12. From paper posted above by DustDevil at Science Direct

    https://www.sciencedirect.com/science/article/pii/S0012825216304068

    5. Recommendations for future work

    More research is critically needed on the older Quaternary caldera-forming eruptions that produced large-volume pyroclastic deposits. These are extensively distributed and exposed and will build a better picture of the early evolution of Taal Volcano, as well as provide an estimate of recurrence rate of large eruptions from Taal Caldera.

    One especially important question is whether and how small eruptions can grow into large explosive eruptions like that of c. 5700 BP. Knowledge of any precursory eruptions (or absence thereof) is important for anticipating a future caldera-forming event.

    Also

    https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2002JB002194

    ]Caldera-scale activity asrecently as 5.3 ka was responsible for widespread ignim-brites which now underlie parts of Metro Manila [Wolfeand Self, 1983;Listanco, 1994]. Future potential for caldera-scale activity is unknown.[5]

    • Would it not be logical to suggest if a very large caldera forming eruption was to occur that the precursors of this would seem highly out of the ordinary and possibly defy explanation? So as long as the signs of activity are recognisable then any event resulting from this activity would be historically familiar?

      • I was watching and thought that is photogenic!

        They had a 3.3 just west of the volcano but inside the larger caldera at 7km about 20 min ago.

  13. Reading the above comments, diagrams and pictures leaves me with one, albeit speculative, concern.

    And that is the current dyke intrusion is not simple, but appears to be widespread and interspersed with numerous sills and sub-dyke off-shoots. It is covering a large area underground.

    My concern is that unless the central edifice can effectively reduce the pressure from the intrusion (and I think it is safe to say it has satisfactorily done so in recent history), we may see a new large-scale and wide area eruptive event(s) and caldera extension to the west of the area.

    It is just a gut feeling. But I don’t really like the way this is going. It reminds me too much of a high-pressure bulge pushing on a weak cap.

    But, that said, the current eruptive phase may not lead to any significant results. Taal may well simply settle down again.

    But it bears close watching for the future.

    • “Central edifice” being of course the current volcanic eruptive structure in Lake Taal. I doubt it is central to the dyke structures below.

    • I was also worried about the effects pressure reduction might have had, but it looks like today there hasn’t been much earthquake activity, intrusion may be over.

      PHIVOLCS is being very prudent and this is good example to follow, it is the way you aboid casualties. It will be several days of carefull watch (but I think it is very likely the whole thing has ended).

  14. TAAL VOLCANO BULLETIN 17 January 2020 8:00 A.M.

    00 volcano icon for bulletin Activity in the Main Crater in the past 24 hours has been characterized by steady steam emission and infrequent weak explosions that generated dark gray ash plumes 100 to 800 meters tall and dispersed ash southwest to west of the Main Crater.

    Existing fissures identified in barangays of Lemery, Agoncillo, Talisay, and San Nicolas in Batangas Province have been observed to widen by a few centimeters. A steaming fissure has been newly observed on the northern slopes of Taal Volcano Island. Receding of the shoreline has been observed around the whole of Taal Lake.

    The Philippine Seismic Network plotted a total of six hundred thirty-four (634) volcanic earthquakes since 1:00 PM, January 12, 2020. One hundred seventy-four (174) of these registered at magnitudes M1.2 – M4.1 and were felt at Intensities I – V. Since 5:00 AM on January 16, 2020 until 5:00 AM today, there were sixty-five (65) volcanic earthquakes plotted, two (2) of these registered at magnitudes M1.3 -M3.1 and were both felt at Intensity I. The Taal Volcano Network recorded nine hundred forty-four (944) volcanic earthquakes including twenty-nine (29) low-frequency earthquakes. Such intense seismic activity likely signifies continuous magmatic intrusion beneath the Taal edifice, which may lead to further eruptive activity.

    Alert Level 4 still remains in effect over Taal Volcano. This means that hazardous explosive eruption is possible within hours to days. DOST-PHIVOLCS strongly reiterates total evacuation of Taal Volcano Island and high-risk areas as identified in the hazard maps within the 14-km radius from Taal Main Crater and along the Pansipit River Valley where fissuring has been observed. Residents around Taal Volcano are advised to guard against the effects of heavy and prolonged ashfall. Civil aviation authorities must advise pilots to avoid the airspace around Taal Volcano as airborne ash and ballistic fragments from the eruption column pose hazards to aircraft. DOST-PHIVOLCS is continually monitoring the eruption and will update all stakeholders of further developments.

    DOST-PHIVOLCS

    • For some reason, no SO2 level today or explanation why it is missing, Interesting other bits in there though.

    • The shoreline of the lake receding is rather unsettling, those are the sort of unusual things to keep an eye on, any venting from other areas well away from the eruption site would be others, anything like that especially if it puzzles the experts.

        • Problem is knowing if this is leading up to some bigger event or just part of a natural cycle and if it is anything serious what sort of timeline, days ,weeks, months., not a nice position to be in lot of uncertainty I would suspect.

        • My gut feel is that this is about as frantic as it’s going to get… unless water inundates a chamber.

          Caveat: I don’t have any formal expertise at all.

          or, “I just plot stuff

          • Probably most likely outcome, unless some destabilising event such as a large earthquake sets of a chain of cascading events then this could go sideways really quick.

          • Yeah, that is the worrisome bit, “History shows again and again how nature points up the follow of man” – BÖC

          • We are unsure who is being asked to contact who. If this is aimed at VC, contact is established through the VC email. We do not contact commenters otherwise. If this is aimed at someone else, please be more specific.

      • This is what is concerning to me. If I’m understanding the above deformation data correctly, the southwest side of the lake is deflating while the northwest side of the lake is inflating. The river outlet, which is now dry, is on the southwest side of the lake. How much water has left the lake if the river outlet has deflated and is still dry? Can all of that be attributable to evaporation from the heat of the eruption?

        • Evaporation seems unlikely, so lake level changes could be some sort of geological effect, major change taking place under and around that lake? Will this just coast to a natural state of balance or keep going until something has to give resulting in another eruption either from the existing site or elsewhere in the complex?

  15. Something for all to concider. Large calderas do not have to form over a short time span. They can take years to grow, expand and manifest themselves. Think of them as occasionally energetic grabens.

    • Media? Good luck with that. They are the epitome of Homo Stultus.

      At least local media personality “Vodka” Bob put on glasses trying to appear more intelligent during the national attention Pensacola got with our shooting at NAS. (He’s still trying to live down his DUI arrest)

      {WEAR News anchor when he’s not in trouble}

      I’m not saying there is anything to it, but he doesn’t even appear in the publicly accessible “Booking” view of our county jail anymore.

      But back in 2008; “According to Glenn Austin, spokesman for the Escambia County, Florida Sheriff’s Department, Solarski was arrested by deputies late Wednesday evening after allegedly hitting several parked cars at University Mall in Pensecola.

      BTW, University Mall went defunct and for the most part was torn down. At one point, all you had were the anchor stores still in operation with what looked like a nice cattle pasture between them where the mall used to be. They have since re-let the properties and other businesses now use the space for stand-alone buildings. The “cow pasture” is used up.

      From what I remember of the initial reports in the paper… he wasn’t “hitting” shopping carts. He got law enforcement’s attention because he was pushing them around the parking lot with his vehicle. ‘Stupid is as stupid does‘ comes to mind. {Quoting Forrest Gump}

      And no, I’m not saying my family is perfect, hell, I had one psuedo relative get picked up because he was doing wheelies in a strip club parking lot on his motorcycle.

      The real stupid, is humanity itself. It’s in our nature.


      As for the “cascade” failure scenario… too many times after the event analysis has revealed that a catastrophe was the result of an unfortunate collection of unlikely events that triggered one another and messed stuff up quite badly.

      Taken separately, the events would likely not have been a problem. But as a cascade failure… nasty.

      Mental exercise for you. Many of you are familiar with traffic lights. For the sake of argument, ASSUME that the probability of catching a green light is 25%. The probability of catching two in a row is 0.25 x 0.25, or 6.25% of the time. Four in a row? .025 x 0.25 x 0.25 x 0.25 = 0.390625% In other words, very rare. But it does happen. (Not counting synchronized lights and each light’s activity is independent of all others) I’ve had as many as five, but that was due to me being able to see the light and read the traffic, adjusting my speed for optimal arrival. (i.e, cheating)

      Note: In actuality, traffic lights are not 25% likely to be green. You have to take into account turn lane periods as well as through traffic. I’ve been meaning to go video a nearby light for a few minutes to get a better idea of the timing, but haven’t gotten around to it. Besides, I can just see myself trying to explain to the sheriff’s department what I am doing should they become interested.

      • In the Military one item that is asked in some equipment casualty reporting is if the problem is a cascade failure event. As far as I know the goal is not in weeding out the ultra rare, it’s to find the ultra incompetent technicians who just throw parts at a problem until it goes away. So naturally this, along with my last comment, is why “cascade” events get my attention.

        Note: Some “cascade” repair events are due to bad parts or one stage of a system killing off adjacent stages. (Think Syncro-Servo systems) ← These can be a bear because the circuits are circular in nature. You chase one symptom up the line to it’s source and it turns out to be a down circuit element whose effect feeds back through the circuit to other elements. The secret is to split the circuit so that it is linear in nature and you don’t wind up chasing yourself.

        My favorite syncro-servo story was told to me by an ancient technician who was called in to troubleshoot the main gun on an AC-130 gunship. The system had a persistent “hunting” fault. This is where the circuit oscillates back and forth around a commanded orientation. Since the circuit in question was for the 105 mm cannon, it caused the aircraft to wiggle back and forth while in flight.

        • There are cascade events in biology too. Positive feedback loops, negative feedback loops. But there is also homeostasis.

          Depends on both the system and the signal.

        • Biology? The “Red Queens Race” comes to mind.

          And with mankind’s pervasive stupidity, just what are we racing against?

          A generally accepted fact; Neanderthal and Cro Magnon cranial capacity averaged 1500 cc. Modern humans average 1250 cc.
          That’s about a 16.6% decline in 40,000 years. The usual story we use to placate ourselves is that we do more with less and are more efficient… but is that not just a species-centric point of view? My contention is that Homo Sapiens (Thinking Man) is already extinct. Homo Stultus (Idiot Man) is the prevailing hominid.

          It was SUPPOSED to be comedy.

          • I was thinking more of the processes that occur during septic shock.

          • Septic shock is a cytokine storm. There is also the complement cascade. Another example might be an epileptic seizure.

  16. Does anyone happen to know what changed in IMO’s display of cumulative seismic moment since the last eruption for grimsvötn?

    As if there was a new calculation method or something…

    • I’m not seeing anything I notice to be different… what are you seeing that looks like it’s changed?

  17. ERUPTION UPDATE FOR TAAL VOLCANO ALERT LEVEL 4 (HAZARDOUS ERUPTION IMMINENT) 17 JANUARY 2020 05:00 PM

    Since 8:00 AM this morning, Taal Volcano’s activity has been generally characterized by weak emission of steam-laden plumes 800 meters high from the Main Crater that drifted to the general southwest. A total of five (5) discrete weak explosions were recorded by the Taal Volcano Network.

    The Philippine Seismic Network plotted a total of six hundred fifty-three (653) volcanic earthquakes since 1:00 PM, January 12, 2020. One hundred seventy-four (174) of these were felt with intensities ranging from Intensity I to V. Since 5:00 AM to 4:00 PM today, there were nineteen (19) volcanic earthquakes plotted. This signifies continuous magmatic intrusion beneath the Taal edifice, which may lead to further eruptive activity.

    Alert Level 4 still remains in effect over Taal Volcano. This means that hazardous explosive eruption is possible within hours to days. DOST-PHIVOLCS strongly reiterates total evacuation of Taal Volcano Island and high-risk areas as identified in the hazard maps within the 14-km radius from Taal Main Crater and along the Pansipit River Valley where fissuring has been observed. Residents around Taal Volcano are advised to guard against the effects of heavy and prolonged ashfall. Civil aviation authorities must advise pilots to avoid the airspace around Taal Volcano as airborne ash and ballistic fragments from the eruption column pose hazards to aircraft. DOST-PHIVOLCS is continually monitoring the eruption and will update all stakeholders of further developments.

  18. And here we get the colours reversed

    https://twitter.com/EricFielding/status/1218066944265318400

    Eric Fielding
    ‏ @EricFielding
    6 hours ago

    New versions of displacement maps for Taal, Philippines from Copernicus Sentinel-1 SAR data by @iamgracebato at NASA JPL show full ground motion in color. Red colors mean land moved up or east, blue mean down or west. InSAR and pixel offsets. We are providing this to PHIVOLCS.

    • That is again the other way around as it seems people had convinced themselves (and myself) yesterday…sorry but it is borderline inconceivable to me that there is so little standardisation about something so obvious…

    • And yet the chart label says LOS displacement. Surely a positive displacement is away from satellite unless specifically stated on chart that it represents decreasing distance. Do the people processing this stuff just make it up as they go along?

      • yes, there is a lack of standardization. the displacement is defined as in the height of the terrain, i.e. larger numbers should be higher. but the measurement gives the distance to the satellite which is the other direction. It all stems from that. In essence, the number changes sign at the final calibration step.

        • Yes, but that means in my private opinion that it would be very useful for the person doing the final reduction step to directly label the map in a fashion that leaves no room for interpretation.

          I can not actually blame anyone, I do not know it from looking at the final map. All I know is that if (if) what Eric Fielding wrote on Twitter is the correct version, even a renowned professional volcanologist got it the wrong way round yesterday in a German Facebook group. That should be quite a warning sign…

      • Okay if LOS Displacement is actually short for LOS Earth’s surface displacement then positive means up but if a chart is just LOS then positive means down. Colours are picked to confuse everyone for no good reason.

        So assuming the above chart is correct then it would seem that volcanic earthquakes, signifying “continuous magmatic intrusion”, are taking place (according to PHIVOLCS) in the area that appears to be moving down?

        • It made much more sense to me the other way But assuming it is like this I can’t really come up with any simple situation to give this deformation, I think more than one source must be involved otherwise it should be just concentric or looking like a butterfly if a dike.

          I just wish we don’t have to wait for papers to be published to know what is actually going on.

          • Single magma chamber produces a concentric signal, this would be deformation of the Sierra Negra summit sill:

            A dyke leaves a diferent pattern, this is from 2008 in Afar, one of the intrusions during a rifting event:

          • Can a admin please delete the second duplicate link?
            This is the good one, intrusion in Afar:

          • That is the blue bits could be going up but that would appear blue if they moved west by a greater distance?

          • But wouldn’t blue be decrease in distance so closer to the satellite and east instead? It would make more sense to me if blue was west but the way you put it earlier it should be interpreted as east/up.

          • This specific chart is captioned in the tweet “blue mean down or west.”

          • Different charts use the same input data but swap positives and negatives and reverse the colour scheme just to make it all more confusing.

          • This specific chart is captioned in the tweet “blue mean down or west.”

            Then it is a dike… It is the exact same pattern you usually see in dike intrusions when the sides move outward. Since the blue moves west/up and the red east/down it looks like extension, rifting… etc. The NE coast may be subsiding as the caldera drains.

            Guess I go back to my initial interpretation.

          • Which magma chamber is feeding the dyke? Apart from one shallow under about the Island itself, very little seems to be known. It seems from what PHIVOLCS are saying (although my interpretation could be wrong) that they believe the magma chamber under the island is still full.

          • It would be expected to deflate every magma chamber Taal has, same as it happens to Kilauea or Ambrym, all the system is affected if you remove magma.

            I don’t know what PHIVOLCS is thinking right now… if the caldera was inflating how the hell do they explain the lake water level has lowered… It doesn’t match. On the other hand if it subsides it explains that part. I don’t think PHIVOLCS is interpretating correctly the situation.

          • Inflation can lower the ground water table, and form cracks that water can drain into. Remember that Krakatau may have dried out prior to its eruption. I would like to see more pictures of the lowering of the lake.

          • It continues to play in the back of my mind that here we have a system that did a VEI 6 at 50 cubic km (perhaps more) just about 6000 years ago and has done similar previously.

            Yet we know almost nothing about it.

          • If anything big happens soon, the timing (winter) could also not be worse.

            To me, the most interesting part of this event so far is the trajectory of the initial high altitude plume on the 12th-13th. From a very tropical and equatorially friendly 14 degrees north latitude, it headed straight north into the jet stream rather than being capped by the tropopause like it would be in the summer.

            Pinatubo was in June when the jet was much farther north and thus, for the first weeks, most of the aerosol first just circled the equator. It was gradually distributed north and south over a period of months. This created a very dispersed global impact versus a potentially more concentrated hemispheric impact.

          • Further reason to think the caldera is deflating and not inflating is in the historic record. During the 1911 events the Volcano Island may have subsided by more than 3 meters: https://archive.org/details/jstor-200468/page/n11

            Taal Lake level lowered by 1 m along the south coast and a bit less in the north coast. If the entire Caldera area subsided during the 1911 eruption that seems to be on the order needed to lower Taal Lake by a meter back then.

            This is wonderful information which shows the 1911 eruption from the Main Crater may actually have been due to underpressure of the summit rather than overpressure. It is hard to confirm but the ring fault of the Main Crater may have ruptured with results similar to the better studied 1968 Fernandina eruption. A largely steam-driven explosion would have then blown material from the crater into a massive base surge.

          • So most of the changes took place before the 15.

            If the Main Crater was taking up water then the level should have continued lowering. With that ruled out it is deformation what is probably to blame. Water has not gone anywhere else or been evaporated, it has just adapted to the new lakefloor shape.

  19. Could the surface area of the lake be increasing causing the lake level to drop, a stretching effect on the caldera?

    • No, that is unlikely. Even an expansion by a meter (huge) would barely change the surface area of the lake.

    • Should of said surface area of the bein contains the lake not the lake itself.

  20. Hmm, I see Raymond Maximo’s Twitter has the polar opposite of displacement I based my speculation on.
    But the principal of what I said earlier stands.

    It may not happen in this or a near-future eruption, but I believe in time that magma pulse will break out somewhere away from the central volcano island.

    • Plan_B is the Deccan Traps were heading for a ‘mildly-anoxic ocean’ event, comparable to the later opening Atlantic’s flood-basalts. Regional damage, but not ‘extinction’.

      Then The Chix’ Rock fell, made a real mess to its North, added to the global atmospheric vog burden and, in passing, fracked the Deccan Traps’ plume from ‘merely nasty’ to ‘totally epic’…

      • I have often thought about that. Since last December, we astronomers often get asked about Betelgeuse, and “Will it go supernova soon?”. Of course we are in a way in a much easier position compared to volcanologists, as no lives are at stakes (at least in our solar system). But the truth is, predicting the next Galactic supernova is — I imagine — much like predicting the next volcanic eruption the magnitude of Pinatubo 1991 or bigger.

        There are candidates, we know it will definitely come. We have absolutely no idea how to predict it down to the timeframe of years. No one knows how a massive star is supposed to look immediately before core collapse.

        Generally, the slow dimming for Betelgeuse is something I think of as happening in the outer “atmosphere” of the star, maybe increased mass loss. Not directly linked to the very core, were a supernova would start. Drawing a rough comparison, I think of it like Steamboat Geyser becoming active at Yellowstone. A sign of a geologically active region? Sure! Harbinger of the next VEI-8? Very probably not!

        The best stellar evolution models we have tell us that core helium burning in Betelgeuse would be relatively fresh, and the supernova maybe as much as 100 000 years in the future. But this may mean less than it sounds. Uncertainties are huge, and it would not be an Earth shaking surprise to anyone if it happens tonight or tomorrow. But I am for the moment not holding my breath.

        The gravitational wave spikes to me look like artefacts, not astrophysical events.

        • The dimming of Betelgeuse is caused by a molecule forming in its atmosphere. TiO is extremely good at absorbing light. A small cooling can in that way cause a large fading. It is quite common in red giants but wasn’t seen before in supergiants, I believe. No panic. No supernova yet.

          • TiO is actually known for very long in the spectrum of Betelgeuse. Actually, this was one of the very stars in whose spectra it was first discovered, by Giovanni Donati more than 150 years ago.

            The depth of the TiO absorption band is one of the criteria for spectral classification of M-giants and supergiants. It is true that this has deepened a bit lately, but even totally saturated absorption in this band could not explain the dimming (which is of the order of a factor of two versus brighter states). I do agree as said that at the moment at least there is nothing pointing towards a supernova.

          • This becomes a technical discussion..

            Here are the AAVSO full light curve for Betelgeuse going back a century, and the recent change. Note that J (infrared) is unchanged, which indicates little change in total energy output (with the proviso that it puts a lot of weight on one data point; I would like to see more!). The U-band (ultraviolet) decline must therefore be a temperature change (cooling). The visual data (V) fades more than the U which suggest additional absorption in this band. TiO fits that bill. There may have been a similar fading around 1941 but there isn’t enough data to be sure. The maximum seems to have dropped below 1 at that time.

            The star Mira fades by a factor of 5000-10000 every year. Of this, a factor of 2 is due to the energy output of the star itself. The rest is due to changes in the spectrum, involving the change in temperature, and the molecules TiO and VO.

          • Here is an example of spectra of stars (not supergiants though). Betelgeuse is in between M0 and M5, the two bottom cases. In this range TiO absorption increases rapidly. By the time you get to M7/8, the light between 4000A and 6000A is almost obliterated. Of course that has to do with the much extended atmospheres of giant stars with cool outer layers.

            And this shows how extreme TiO and VO can get in supergiants: lowest spectrum. That is for a much more cooler star than Betelgeuse though.

          • Hi,

            there are some things a bit confused.

            First, please let me state again that at the moment, no one has a convincing explanation for the fading of Betelgeuse. That in itself does not mean a lot. Many things about evolved massive stars are unexplained. The star is known to be irregularly variable, and it may simply be that we are seeing a deeper dip than usual.

            What we know is that it is not simply the new formation of TiO that is causing this. Why do we know that? Quite easy! TiO has been known in the spectrum of the star for very long. It’s absorption properties are very well understood. Look at the yellowish plot you posted. A star is in reasonable approximation a black body with lines and bands superimposed. Compare the width of the TiO bands with the bolometric emission. Even if the absorption were total within the bands (which in fact can never happen), this would not be sufficient to cause a drop of a factor of 2 in total luminosity. Not by far.

            These types of stellar variability normally never come from changes in the “energy output” of the star, because the nuclear reaction in the core tend to run their cause until there is not enough fresh material left. However, that is a bit of an academic point, as even in the Sun, energy that is produced right now will take hundreds of thousands of years to reach the surface and be radiated into space. So, the stellar atmosphere has ample opportunity to store away parts of the energy and make it seem to us as if the energy output changed. That may be happening in Betelgeuse at the moment: the star may expand, cool a bit, loose material into it’s vicinity, which cools more, forms dust and blocks some light. A fraction of the energy gets hidden in the work required to expand the star, for timescales we Earthlings think long, but are in reality a blink of an eye. The increased formation of TiO and other molecules would then be a by-product, a symptom but not the cause of the fading. Time will probably tell.

            You mention Mira-type variable stars. There, the mechanism driving the variability is what we call the Kappa-mechanism. Strongly simplified, changes in ionisation because of small temperature changes can lead to huge changes in opacity, thus trapping some light in the star until it heats, expands, becomes more transparent, contracts, and so on. For Mira-stars it is the ionisation of hydrogen that is driving this. TiO is again just a by-product. There is an even more important class of hotter stars (the Cepheids), where the driver is helium.

          • I don’t disagree with any of this. In Mira variables, the kappa mechanism drives the pulsations, and because the growth rate of the pulsation exceeds the damping, the pulsation becomes very large and regular. In Betelgeuse, the pulsations are less regular (at most times) and the excitation may be more stochastic and the damping more important. But the byproduct TiO severely amplifies the effect on the visual brightness. The bolometric luminosity of Mira varies by factor of 2. But the visual luminosity varies by a factor exceeding 1000 (it varies per cycle). This comes from the fact that Mira stars have very extended atmospheres with cool outer layers. In the TiO bands, you see the outer, cool layers while in the infrared you can see the deeper, warmer photosphere. A small change in TiO gives a large change in the light that comes out in the visual. Our interpretation of Betelgeuse’ fading is that it is caused by a similar effect, as it one of the supergiants that has an extended atmosphere.

            You are completely right that changes in the core of the star cannot have instant effects on the outside. A funny result: Mira shows flickering on a time scale of seconds to minutes, visible only at minimum. It is attributed to material expelled from Mira and accreted by its companion (https://arxiv.org/pdf/1803.04338.pdf).

            As you do, I think tere is no relation between the current fading and a future supernova eruption.

          • Indeed, the fast “flickering” interpretation as accretion onto a WD is extremely interesting. Are you working on that system?

          • Albert, you from UManchester?

            Funny to meet another astronomer on a volcanology blog 😉

          • Not so strange: astronomers are the only people to build their observatories on volcanoes. Volcanologists don’t do that..

          • I didn’t know that one. At least the observatory wasn’t on St Helens itself!

          • Yes, but it is quite hilarious! I often use it in lectures when talking about unexpected things that can happen on observation runs…

          • I have been lucky with no nasty surprises during observing runs. Got stuck inside a dome once during a 120 km/h, and once had to shovel ice on top of a dome on Mauna Kea when it wouldn’t close. But accidents at observatories tend to be nasty because help is very far away. Safety is paramount in what are dangerous environments. One place I was made me refill the dewar (liquid nitrogen only) wearing almost a spacesuit. Another place recommended doing it in shorts and t-shirt. The most dangerous thing bout liquid N2 is freezing clothes to the skin, so not wearing any was seen as much safer!

        • Now I know even less about astrophysics than volcanoes, but a question; is it technically feasible to get a Betelgeuse spectrogram, and would it give any clues about the fusion reactions currently (well 690 years ago to be pedantic) dominant?

          • There are of course spectra, but those can show the conditions in the outer layers only. Impossible to peak into the heart of the star this way…

            In a few years from now, the Super-K neutrino detector will be fully upgraded by adding gadolinium to the water in the detector. It may then be that it will be sensitive enough to see the neutrinos also from the final burning stages, giving an additional 12 hours to a few days of pre-warning. The neutrinos from the core collapse itself would be impossible to miss even today.

          • Addendum: I realise that you probably think of a seismic spectrogram, whereas I think about an optical spectrum. Good point actually. Unfortunately, todays telescopes can not really do asteroseismic measurements in such cases. It is done very successfully for our Sun of course.

          • Addendum II: (clicked send too early)

            …and is attempted for Betelgeuse, with the very goal you named. But, as said, it is pushing today’s instruments probably too far to presume this could give a precise answer to the supernova question just yet.

    • Could this represent the hypothesised binary partner, now orbiting *within* Big B’s extended envelope, finally taking the ‘Long Drop’ ??

      If so, there should be a splendid neutrino ‘burp’ followed by an awesome ‘shell’ ejection…

      • Regarding final evolution of such a system, uncharted terrain, I think. Modelling a single evolved massive star is hard enough. Actually not even feasible in full 3D today.

        Regarding the GW spikes, they are much shorter than any conceivable timescale for that. As said, my best bet would be artefacts.

        Should core collapse finally happen, yes, we will without any doubt know because of the neutrino burst. At just 600 light years distance, the “brightness” will be monumental. Twelve hours later, shock breakout will happen with a brief (minutes to an hour) infrared/optical/UV flash. Followed over weeks and months by the optical supernova.

        In contrast to the volcano girls and guys, who probably always have the potential loss of life in their minds when thinking about the next big eruption, a close Galactic SN is something I think everyone is looking eagerly forward to.

    • Not oh deer…but oh Yay actually.
      The star is far away enough to not cause actual damage. But will still produce the lightshow of the millenium.

      It would be a honor to see it.

  21. Whats the temperature and viscosity of Taals basalts?
    Im soure they are cold viscous subduction zone basalts.

    The recent fountain was breath – taking!
    That magma is Probaly full of Co2 and water

    • That is not a small fissure. The 7.1 earthquake in California last year left a crack about that size, maybe smaller.

  22. Is the caldera getting stretched by an influx of fresh magma at depth, almost like rolling out pastry dough the pastry trends to get thinner in the middle and bunch up on the edge, in the caldera this tends to shallow out the ground in the middle of the caldera creating hydrothermal activity and increased likely hood of eruption with less over pressure the rock to hold it in, as I said earlier is the water not actually receding but the shore moving way from the water in all directions? Forgive my intense ignorance and simplicity, just curious that’s all?

    • I just commented further up on how the 1911 may have occurred based on observations from the time. It more or less goes the way you describe. But today it seems that the intrusion is paused or over (not much earthquake activity), situation may be returning to normal.

  23. I dont know how to post links but there is an AMAZING photo of the Taal eruption taken from the Taal Vista Hotel by coffee_dante on Instagram.

  24. While we watch and wait. here’s a wider regional look at 7 days all magnitudes from PHIVOLCS

    Yellow 0 – 32km
    Green 33 – 69km
    Red 70 – 299km

  25. Activity in the Main Crater in the past 24 hours has been characterized by steady steam emission and infrequent weak explosions that generated white to dirty white ash plumes 50 to 600 meters tall and dispersed ash southwest of the Main Crater.

    Sulfur dioxide (SO2) emission was measured at an average of 360 tonnes/day yesterday, consistent with weak plume activity at the Main Crater.

    The Philippine Seismic Network plotted a total of six hundred sixty-six (666) volcanic earthquakes since 1:00 PM, January 12, 2020. One hundred seventy-four (174) of these registered at magnitudes M1.2 – M4.1 and were felt at Intensities I – V. Since 5:00 AM on January 17, 2020 until 5:00 AM today, there were thirty-two (32) volcanic earthquakes plotted, registered at magnitudes M1.5 -M3.3. The Taal Volcano Network recorded eight hundred seventy-six (876) volcanic earthquakes including six (6) tremor events and twenty (20) low-frequency earthquakes. Such intense seismic activity likely signifies continuous magmatic intrusion beneath the Taal edifice, which may lead to further eruptive activity.

    Alert Level 4 still remains in effect over Taal Volcano. This means that hazardous explosive eruption is possible within hours to days. DOST-PHIVOLCS strongly reiterates total evacuation of Taal Volcano Island and high-risk areas as identified in the hazard maps within the 14-km radius from Taal Main Crater and along the Pansipit River Valley where fissuring has been observed. Residents around Taal Volcano are advised to guard against the effects of heavy and prolonged ashfall. Civil aviation authorities must advise pilots to avoid the airspace around Taal Volcano as airborne ash and ballistic fragments from the eruption column pose hazards to aircraft. DOST-PHIVOLCS is continually monitoring the eruption and will update all stakeholders of further developments.

    • They said yesterday (to the media) there were problems with the SO2 measurement and they were working on fixing. I’m not sure how good given values for previous days were.

      • I was always a bit suspicious about data given to four significant figures…

    • The Philippine Seismic Network plotted a total of six hundred sixty-six (666) volcanic earthquakes

      I’ll just dig my shelter now 🙂

  26. I doubt all the earthquake activity and ground deformation is directly correlated to the eruption site, more the eruption is secondary to those other factors.

    • So what is happening at the eruption site now possibly does not indicate or foretell what will happen with this ongoing event, the seismic and deformation data is more where the story is.

  27. ERUPTION UPDATE FOR TAAL VOLCANO ALERT LEVEL 4 (HAZARDOUS ERUPTION IMMINENT): 18 JANUARY 2020 06:00 PM

    Since 8:00 AM this morning, Taal Volcano’s activity has been generally characterized by weak emission of steam-laden plumes 500 to 800 meters high from the Main Crater that drifted to the general southwest. A total of two (2) discrete weak ash explosions were observed.

    The Philippine Seismic Network (PSN) plotted a total of six hundred seventy-three (673) volcanic earthquakes since 1:00 PM, January 12, 2020. One hundred seventy-five (175) of these were felt with intensities ranging from Intensity I to V. Since 5:00 AM to 12:00 PM today, there were thirteen (13) volcanic earthquakes plotted.

    From 5:00 AM to 4:00 PM today, the Taal Volcano Network, which includes small earthquakes undetectable by the PSN, recorded three hundred sixty-six (366) volcanic earthquakes, three (3) tremor events, and eight (8) low-frequency earthquakes. Such intense seismic activity likely signifies continuous magmatic intrusion beneath the Taal edifice, which may lead to further eruptive activity. Latest sulfur dioxide (SO2) emission was measured at an average of 1442 tonnes/day today at 5:00 PM.

    Alert Level 4 still remains in effect over Taal Volcano. This means that hazardous explosive eruption is possible within hours to days. DOST-PHIVOLCS strongly reiterates total evacuation of Taal Volcano Island and high-risk areas as identified in the hazard maps within the 14-km radius from Taal Main Crater and along the Pansipit River Valley where fissuring has been observed. Residents around Taal Volcano are advised to guard against the effects of heavy and prolonged ashfall. Civil aviation authorities must advise pilots to avoid the airspace around Taal Volcano as airborne ash and ballistic fragments from the eruption column pose hazards to aircraft. DOST-PHIVOLCS is continually monitoring the eruption and will update all stakeholders of further developments.

    DOST-PHIVOLCS

    • I have my doubts that one side has dropped. Looking at the image, the side to left of the picture has been uplifted by some margin based on the jetty (top left corner) and shoreline being left high and dry.

      • Yes, it is very complicated. We know that the lake level has lowered, also as you say the left side has probably been uplifted which would be consistent with the interferogram but at the same time right side has probably dropped since some houses in Agoncillo which falls to the right have been flooded by water from the lake.

        • Ah, if there has been inundation of the house in that image, then yes, that could suggest areas have dropped and also be the reason shorelines are then left high and dry as the lake water is covering new areas. A counter view could be that if there has been asymmetric uplift of parts of the lake floor, then areas that have not uplifted, or at least not dropped, could also become flooded? Complicated, as you rightly say.

          Looking at that image again, looks like a lot of dead fish on the shoreline?

          PS – Thumbs up for the OP/update, many thanks.

  28. Finally absolute values

    https://twitter.com/SotisValkan/status/1218570561745539073

    Sotiris Valkaniotis
    ‏ @SotisValkan

    (Very) preliminary absolute displacement maps (horizontal & vertical motion) for #Taal volcano area, Philippines. Combining ascending & descending #Sentinel1 interferograms. Looks like extension is larger than vertical deformation. Local spots could have higher values @esa_gep

    Please note that “red (negative) values are towards west” chart is wrongly labelled – see twitter comments

    • Side note: if it were not such a serious situation for the affected people, it would be quite surreal that again the plots were first mislabeled…

      Anyhow, finally! So it seems the area were the majority of quakes happened is also rising, as well as the southern area. Only a small part of the measured region is sinking.

      How does this fit with the dyke hypothesis? The east/west extension probably quite well, right?

      • Yes, it fits perfectly. Uplift and extension is expected around a dyke which seems to be the case. There should also be deflation of the magma chamber as magma is drained away which explains why the east/north coast of Taal Lake has subsided (this is away from the dyke so deformation from the magma chamber is more important here).

        Again it is very similar to deformation during 1911, but on a seemingly smaller magnitude this time.

        • Yes, you got it right. Note that the new map (using an additional radar image taken yesterday) can see motion east-west and up-down, but not north-south. We don’t know about extension that direction. This means that the westward, deflating area on the east side of the lake could still be pulling apart north-south.

    • Seems to me to be perfectly tectonic. event which triggered the eruption.

      • I would put it the other way around. A volcanic eruption at Taal that grew into a larger tectonic process.

        Studied rifting events have always started with a small intrusion from a volcano that probably aided by accumulated extension (tensile strain) grows into a really big intrusion.

  29. Thanks DustDevil and Squonk!

    Reading about “fissures” (NFI) in the PHIVOLCS bulletins was a bit frustrating. Your post and the map make it a lot clearer.

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