Growing harmonic tremor spike in Katla volcano

It seems that Katla volcano is going to keep me busy for coming days and weeks.

At this moment it seems that there is a growing harmonic tremor in Katla volcano. This harmonic tremor started today after the earthquake swarm that took place earlier today. After it stopped a spikes of small harmonic tremor spikes did start to appear. During the past few hours they have been growing in size. But it seems that the harmonic tremor drops for few moments between spikes.

Earthquake swarm that took place yesterday in Katla volcano. Copyright of this picture belongs to Iceland Met Office.

This earthquake swarm was mostly small one. With largest earthquakes going up to around ML2.1.

Slysaalda SIL station. Harmonic tremor appears poorly on this SIL station. Copyright of this picture belongs to Iceland Met Office.

Rjúplafell SIL station. The harmonic tremor signal can be seen here clearly, even if it a small one. Copyright of this picture belongs to Iceland Met Office.

Lágu Hvolar SIL station. The harmonic tremor signal can be seen poorly on this SIL station. But it signalled with minor change in the background noise on this SIL station. Copyright of this picture belongs to Iceland Met Office.

Álftagröf SIL station. The harmonic tremor spike can be seen most clearly here, as it goes clearly above background noise. Copyright of this picture belongs to Iceland Met Office.

From what I can tell this harmonic tremor signal is growing every few hours or so. It is possible that this is a repeat of what did happen in July. But for the moment it is too early to know that for sure at the moment. But for the moment there is no eruption about to start in Katla volcano.

When I was writing this blog post, it seems that a new earthquake swarm is about to start in Katla volcano. But the earthquake swarms in Katla volcano often start slowly with few earthquakes, but they seems to grow with time.

100 Replies to “Growing harmonic tremor spike in Katla volcano”

  1. I must concur with Irpsit’s reasoning from the last thread: Katla is tracing a similar path to that taken by Eyjafjallajökull.

    1. While I agree with much of Irpsit’s reasoning, there are a few facts I’d like to point out:

      a) It is true that the last series of more or less continuous earthquake activity lasted some six weeks and if you include a short break 2½ months in Eyjafjallajökull (please Icelanders, do give Her Ladyship a proper name!). But activity in the form of major earthquake swarms, as substantial and sustained as the 2010 one, preceeded the eruption by a small matter of two decades.

      b) During the last six weeks before the 2010 eruption, the IMO plot for the Mýrdalsjökull area over the last 48 hours contained on average some 300+ quakes. At this very moment, the count stands at a mere 44.

      c) Compared with the monitoring equipment now in place around Katla, that which covered Eyjafjallajökull over the period 1991 – 2010 was both scarce and primitive.

      d) No two volcanic systems are ever exactly alike, nor the signs that an eruption is imminent.

      In spite of these caveats, especially the last one as Katla does have a magma chamber whereas Lady E does not (it has a series of sills), I do agree with the timeframe suggested by Irpsit with a couple of exceptions. First, with a substantial magma chamber that has been fractionating for almost a century, all it might take is one large magmatic intrusion directly into the magma chamber and Katla could erupt within days if not hours. In this case there would be little of those signs. Second, Katla may have a flank eruption and by that I mean an eruption that does not involve the main magma chamber. If the latter turns out to be the case, we’d get a VEI 3+ Surtseyan eruption of sub-Plinian proportions.

      Looking at the GVP eruptive history, we could tentatively divide the eruptions of Katla based on known type or by size (VEI 4 or below = flank, VEI 5 or larger main magma chamber) as follows:

      Main magma chamber eruptions: 960, 1262, 1357, 1625, 1721, 1755(?), 1918

      Flank eruptions: 920, 934, 1150, 1177, 1210, 1245, 1311, 1416, 1440, 1450, 1500, 1550, 1580, 1612, 1660, 1823, 1860

      The 1755 eruption is the only anomaly in this series. It is listed as “VEI 5?” and “E-W fissure in center of caldera”

      There are a few things to note when you do a subdivision such as this. First, it is very arbitrary. Second, the hypothesised link to Lady E is confined to flank eruptions. Third, there seems to be no correlation between flank and main magma chamber eruptions. Fourth, the interval between eruptions involving the main magma chamber ranges between 96 and 302 years (excluding the 1755 anomaly).

      Please note – amateur speculation and reasoning!

      1. First of all, the name of the volcano is Gudnasteinn, the glacier is Eyjafjallajökull. But it seems the Icelanders do not want to point it out that the actual name is so mych easier to pronounce 😉

        The hypothesis that Eyjafjallajökull (stop complaining, we have an ö on our keyboards at least) does not have a chamber is just a that. There are other papers stating that it has one.
        More to the point, I agree with Dr. Boris Behncke that pretty much no volcanos has a “magma-chamber”, and that the proper term would be “magma-reservoir”. In reallity we are talking about tubinged, silled, dyked, hollowed mazes in the most “chambered” volcanos. And then the pure hell versions of Hekla and Etna. Eyja has a “magma-reservoir”, it is not shaped like in an instruction video on discovery, but then none are.

      2. One point Carl, the Guðnasteinn is a maintain peak, a rock tip, on the rim on Eyjafjallajökull (Eyjafjalla-Glacer, true) volcano CRATER but there are also other detail names on this mountain, that are unrelevant! Eyjaföll (plural) is name of the whole mountain range, the Jökull covering the peak of the mountain and the crater (caldera if you prefer, but most everybody here in Iceland however uses term “crater” (gígur), not caldera for the “volcano outlet” of Eyjafjallajökull -that is a Volcano – and formed in multiple eruptions over long time. I read shomewhere that “age” of Eyjafjöll and /or Katla was about 700,000 years).
        Nitpicking, true, but this is I how I prefer explaining this mountain.

    1. Yes, it certainly got my attention. Have you looked at the tremor plots? I wish I could understand them better.

  2. There are a number of earthquakes in the caldera now? That would indicate what? Something forcing it’s way into the volcano?

    1. Well as Jón said in one of the last posts, it could be a dike intrusion. But it seems that the activity is definitely picking up in Katla. Less time between swarms, and larger earthquakes in the swarms.

      I suggest that you read Irpsit’s long comment near the end of the last post about what to expect of Katla in the coming months.

  3. Good morning all
    Katla seems to have severe indigestion this morning 🙂
    Jon was right about more quakes after the four on the Raykjanes Ridge the day before yesterday.!
    Out of interest and maybe someone can throw in some suggestions. Have a look at the GPS readings for Vestmannaeyjar here. Very obvious deformation. Is this due to shove from the MAR or volcanic?

    @ Irpsit Thank you for your most interesting writing on the last post. This morning I read about Vestmannmaeyjer. Another place for me to visit on my dream holiday in Iceland. What an interesting place, I remember the eruption well. My babies were very young then and so I had more insight into the worry of those parents. I felt so sorry for the people there as they were evacuated. But what a happy ending! The world Cheered!
    True Icelandic heroism and determination.

  4. ‘Morning!
    So after all it seems that eq activity on N Atlantic ridge does affect and ignite harmonic movements!
    Anyhow a busy period for mamma Gaia the autumn season.

    1. I does not. This is completely unrelated and there is most certainly no connection at all. Earthquakes happen often at the Reykjanes Ridge and the fact that it coincides with an earthquake swarm in Iceland is therefor not uncommon.

    1. Shhhhhh! Ms Katla! Irpsit needs beauty sleep! I was wondering when Jon get’s sleep. Do you in Iceland sleep more in winter than summer? Lol!
      Very off Topic but amusing for me.
      I see an Icelandic spider on the webcam at Austurvöllur. It must be a hardy species! This got me wondering what species of Arachnid survive in the northern Lattitudes! Something else for me to study!

        BY J. H. EMERTON,
        Boston, Mass.
        Since the report on the spiders of the Canadian Arctic Expedi- tion of 1913 to 1916, the writer has had opportunity to examine a considerable number of arctic spiders from the American Museum of Natural History of New York and from the Zoological Museum of Copenhagen, Denmark, the latter including some from Iceland. The Iceland spiders appear to be mainly species living in the British Islands and Northern Europe, while those from Greenland are for the most part Canadian, extending westward to Alaska and Siberia, and southward through the bogs of Canada to the mountain tops of New England and the Rocky Mountains of Canada and the western United States. The following notes give the results of comparisons of spiders from Greenland with those of the same or similar species living in Canada and the mountains of the northern United States. ”

        I found several links on Icelandic Spiders. The above is a most interesting read. It shows, I suspect, the species separated by tectonic plate movement rather than purely climate as theoretically, Icelandic spiders and Greenland spiders, being in a similar habitat, should be of similar species.
        Ahhhhh! The fun of learning and theorising! 🙂

      2. 🙂 at Amandus & Byz Love it. My imagination is running wild here!
        PS @ Jon. The Northwest UK is suffering a backlash from Hurricane Irene, Torrential rain and gale force winds!
        A good excuse to be “busy” on my PC here!

      3. People don’t sleep in Iceland. That’s a myth. You have to come to Iceland yourself to see that for yourself, and maybe give it a try. It doesn’t hurt.

  5. I will stick my neck out and say that in my opinion, Katla is without a doubt the most awaited volcanic eruption in history.
    Expect the unexpected. There is no way that the “bullying housekeeper” will do what we expect. That is her reputation a bully, history and folklore in Iceland is a good reference to how Katla will behave maybe.
    I bet she at least waits till we can’t see her because of the weather or the permanent night of winter or both 🙂

    1. Oke, then ain’t it better to ignore her? 😀 I’ll bet she’ll be upset.
      Let’s talk about Ajka! or Laki, maybe Toba…whatever.

      Sheeps?? Spiders fashion show 😀 you name it!
      Oh, dear, Jon! give as a hint 😀

      1. Oh no don’t ignore Katla 🙂 , that is when she will throw a punch.
        Henrik’s other options:- Flank eruption or fissure.
        If it a flank, Godabunga to the North West, or maybe the easy route to the sea, South-ish?
        A fissure eruption would go from the Caldera in a North Easterly direction I presume. (Only guessing by me)

        OT but in a way connected.
        Atlantis, when it disappeared, people tried to sail to where she was but could not get there because of “mud shoals” their primitive boats grounded, for years they could not go there. When they finally got through the sea there was nothing.
        When large volcanoes do large flank eruptions into the sea or caldera collapse and the sea rushes in, the pumice ash and rocks would make it hard to approach for years perhaps, with primitive boats.
        There could be huge calderas underground covered by modern eruptions, filled by modern volcanic activity, even remelted and erupted out of our knowledge, all trace gone.
        What I am saying is that thousands of years ago Iceland could well have been Atlantis, disappeared not. Just forgotten. Legend says the people knew she was going to blow up so left, scattering to the four corners of the world, they never went back. People who had been there looked but could not find her, in their primitive boats. Little wooden things with sails and a shed on top.

        Pure speculation on my part, please do not read anything bad into this, I mean no harm, I enjoy myth and legend and that is all it is.

      2. Godabunga is most likely not a part of Katla volcanic system. Some have theorized that Godabunga is a part of Eyjafjallajökullsgudnasteinn. Personaly I vote that is a pending volcano to emerge that is totaly of its own making.

    2. It’s not that bad. It can be a repeat of Eyjafjallajokull and cool the climate, and depending on how that plays, it can be not that bad or can be serious. But many other eruptions were way larger. Pick Tambora or Santorini and you have much disasters in mankind history. I guess a common eruption of Katla can be about the power of last Grimsvotn eruption, lasting longer.

      1. You know that you have to count the entire half of the globe… Country by country is just anecdotal.
        For myself I have been sitting in my briefs sipping drinks the entire summer with sweat poring off my pinklu burnt swedish body… Thing is the words “on average”.

      2. Mmmm, the warmest summer on the northern hemisphere…. In that case Switzerland is somewhere else. Only the ladt two weeks of August were warm :-/
        ( I know, totally OT. Sorry)

    1. At which sil station can you see this most clearly Jon? I am having trouble trying to find a clear harmonic tremor at the moment.

  6. I’m not an expert but I do imagine the magma Earth mantle as a fluid one, then it comes the Icelandic hot spot as leaking spot on its crust. Reykjanes Ridge is a nearby surrounding of this giant pore.
    Then the magmatic nature for all Atlantic Ridge for eq activity.
    From the fluid theory one “stormy bulge” spread a lot of “noise” here and there …
    Is this so out of reality??

  7. Jon, (1) if it keeps up the speed like it is now, when can we expect an eruption?
    (2) And what would happen at the time Katla blows?(3) Are you sure everyone nearby can evacuate?(4) What would the damages be both for Iceland and Europe?

    1. 1) It is impossible to know this. 2) There is going to be a glacier flood, a large one and a ash cloud. 3) There are up to 6 hours to evacuate people when the large earthquakes start in Katla volcano. 4) All damage would be localized to Iceland. But the ash cloud drifts according to wind at the time.

      1. Damage is localized to Iceland, but the eruption is sufficiently large, can disrupt flights, cool Earth’s temperature and affect negatively farming and the already fragile global economy. That would not be good for anyone.

    2. That was alot of questions and I bet all of them can be answered with a “I dont know”. But Ill leav it up to Jon to say so. 😉

      Volcanoes are unpredictable and trying to predict something unpredictable is like trying to stop an immovable object with an unstoppable force. 😉

    3. Found one article which might help: Full article here:
      http ://

      It seems as though scientists are expecting a much larger version of Eyjafjallajokull – more ash emissions and local glacial flooding. Possible consequences are a drop in global temperatures. Impact on flights etc will depend on ash composition but as silicates are likely so flights may be grounded. Impact on people & livestock in Northern Europe will also depend on gaseous emissions (I can’t find much data on this on the internet – Icelanders may be able to find more). The past two summers and last winter were colder in the UK, due in part to Eyjafjallajokull & Grimsvotn, and there have been other erruptions this year so we can expect global temperature to drop a bit.

      If Katla does errupt, let’s hope it does after crops & animal feed have been harvested and livestock can live in its winter quarters.

      1. The harsh winter has nothing to do with the Icelandic volcanoes, they are far too small to cause an impact. And the proof comes in this: the winter 2009-2010 was also a very cold one, and the eruption only come after. An eruption needs to be at least 100 times bigger than Eyjafjallajokull or Grimsvotn to cause a significant climatic effect (VEI6). But even Pinatubo in 1991 had a very small effect.

        The reason why we are having a cooler climate trend is due to a change in oceanic cycles, that happens about every 60 years or so. This might be caused in part by low solar activity.

        The winter before last eruption of Katla in 1917-1918 was already pretty cold, the winters following were even colder. The VEI5 eruption add a just an extra cooling to that trend. We could expect that after the next eruption of Katla, if it’s a large VEI5. But this depends also in the type and amount of gases and ash release. A large fissure eruption (which has minor explosive activity) and that releases a huge amount of sulphur like Laki can have a drastic cooling effect.

  8. Regarding any “imminent” eruption of Katla, I would say only the media would rejoice, as they can dramatise and report on it ad nauseum, especially if eruption is big enough to discommode the airlines, or worse.
    The Icelandic people would not rejoice as they have their own problems and an eruption would not help, except for tourists who wish to try look down the throat aof an active volcano. But for Icelanders an eruption would be very inconvenient…so maybe Katla can continue to burp and rumble, but no vomiting, please.

    1. I really agree. I don’t want an eruption. First it’s a mess. Suffering of people in Iceland. It can affect everyone in the planet in a negative way, disrupt flights, farming and crash the economy. Don’t be foolish wishing for these large eruptions.

    2. Not sure that even the media would rejoice. The British press would probably give us wall-to-wall hyped up coverage (even hysteria, depending on the channel / paper) but they do not celebrate real disasters. If the erruption was minor and produced great pictures, yes they would be happy – pictures sell; but if it was major and lives were lost, they would be saddened as would we all.

  9. The current best SIL station to monitor the harmonic tremor is Álftagröf, it has the short name alf on the IMO tremor map.

    That station is directly south of Katla. But it is a fact that Álftagröf is directly inside the Katla volcano. But Katla volcano system goes down to Dyrhólaey in a narrow point according to my geological map. As there is a minor fissure swarm to the south of Katla volcano.

    1. Another smail spike from the link below.

      This current swarm, has it last since yesterday or do they get counted a separated ones?

      I have notice the active area on the south flank is not so active after the 1.9 EQ the other day. Just guessing but could the fluid now of found a more direct path to the old 1918 area, looking at the current picture, the EQ’S still cover a big area and not enough focus to them, but any 3+ could change that.

      Any news about the summers new pits at the top? Have they got bigger in the last two weeks?

      1. That chart is very compressed. IMO should reduce the time range to make it useful again.

  10. The IMO seems to be showing a surprisingly large number of quakes at a depth of 1.1km. Does this suggest a blockage of the magma?
    Does the depth include the thickness of the ice? My checking seems to show it’s around 500-600m deep where most of the activity is occurring, so the magma might be getting to within 500m of hitting the ice bottom.

    The area of activity is interesting to, it seems to be in the cauldron where it went off in 1755, if this is the case the jokullhaup might possibly drain to the SSW rather than to the SE as is usual for Katla.

    1. As far as I know, the depth is below the ice and not including it but Jon will confirm if that is right.

      1. I would use glacial flood or glacier run (what would be more or less the direct translation). It makes less problems with spelling 🙂

    1. Sorry, I posted the link on this path, because this time there were sheep, it seems that young people are doing trail. Enough people walking.

  11. Tuesday
    06.09.2011 12:26:50 63.620 -19.201 5.5 km 1.3 88.38 3.3 km SE of Goðabunga
    06.09.2011 12:26:49 63.642 -19.146 1.1 km 1.2 90.04 5.1 km E of Goðabunga
    06.09.2011 12:26:36 63.643 -19.125 1.5 km 1.8 49.72 6.2 km E of Goðabunga
    06.09.2011 12:23:47 63.642 -19.130 0.1 km -0.2 44.13 5.9 km E of Goðabunga
    06.09.2011 12:21:15 63.643 -19.134 1.1 km 0.1 58.66 5.7 km E of Goðabunga
    06.09.2011 12:08:34 63.640 -19.227 3.9 km -0.6 49.23 1.1 km E of Goðabunga

  12. Get ready! It’s gonna blow now any time. People at Vík in Mýrdal should get there ark ready, there will be FLOOD!

    1. And you base that on? Unless its a doom n´gloom rant which is so popular nowadays of course…

    2. In general the flood will pass close to Vík but not in Vík itself. But the flood might cause a minor tsunami upon entering the sea. I think the really scary thing is waking up to a large eruption. It was big enough with Grimsvotn in Kirkjabaerklustur (pitch dark the following morning) and it was 50km away. Vík is going to get many cms of ash.

  13. Lurking, I would appreciate if you do something!!

    A graph, relating the depth over time, of all the earthquakes larger than 1.5 since let’s say August 2010, and only from Katla (not from Godabunga). This way we could probably see how much magma has been forcing its way upwards.

    Anyone wants to check if there is a decrease in depth of these earthquakes?

  14. Very good blog, and very learning and interest reading! Thanks Jon, and all of you other writers 🙂

  15. Just a short Question to everybody:

    Am I the only one who thinks, that most of those quakes at Myrdalsjökull are mainly caused by the Hydrothermal System inside the Katla Caldera, and not directly through magmatic movements?

    I mean, almost all the quake are very shallow, which indicates the involvement of hydrothermal fluids, not Magma! I don’t dispute, that there is a Heat-Up at Katla, but i don’t think that we should look at every quake and think BaBoom, Magma! Instead, i believe, we should try to understand this as a sign of increased heat-flow, which doesn’t neccessarily mean that Katla is going to erupt in a geologically “short amount of time”. The timeframe could easily be 10Years or longer, one only has to compare the signs of activity at Katla with the ones at Eyjafjallajökull, which started to show signs rougly 20 Years before it actually erupted!

    What we really should look for are Quakes from a Range of 6km and deeper, because those are the really interesting ones in my view. They would be bellow the “Hydrothermal Range” of about 0-4km and almost certainly be a clear sign of deeper magmatic movements. To talk about Intrusions when Quakes are less than 4km deep, feels in my amateurish view a bit exagerated.

    I hope i didn’t offend any of you with my critique, but i had a need to write this.

    Beste Regards

    1. But Stephan the magma chamber in Katla has a depth of 3-6km, its magma is very shallow, and where most of the earthquakes are actually happening

      1. That could very well be right, i won’t deny it, but for a volcano to erupt there needs to be an inflow of fresh magma, in Katlas Case that would be Basalt from the Mantle. The same has happened with Eyjafjallajökull, there were two or three Episodes during which a magmatic Intrusion happened. Untill now, i haven’t seen such an Episode, or did i miss it?

        The first in Intrusion at Eyjafjallajökull took place in 1994-1995, the second in 1999, and the third one early last year, shortly before the Eruption.

      2. Stefan, you wont see the main bulk of the intrusion since it is done over many years.

        So the answer is, you have missed it. Or more to the point. You had an influx in 2002, another one during winter and summer, with very little quaking really. The quaking started after this intrusion.
        You are way to much into seeing quakes as the means to detect magma. That is in main done by GPS monitoring, harmonic tremorin and so on.
        So the real answering is that you are seeing it all the time, and have seen it for long.
        The quakes are fracturing, which is sometimes caused by magma.

    2. As far as i understood the considered magma chamber underneath Katla is located approx 4km deep.

    3. Does the fact that the current pattern of the quakes is smaller to larger have any bearing on the discussion?

  16. Stefan, yes Eyjafjallajokull started to show signs it might erupt back in 1994 when there was an intrusion, but it is widely known that Katla has been building towards an eruption for a very long time now. Katla is close, but yes we don’t know how close.

    Interesting activity today!

      1. Maybe they know something we don’t! Local Farmers often have a 6th sense….or they of course are bringing in sheep from higher pastures before the weather turns towards winter.

      2. Out of curiosity. Do the sheep belonging to all the farmers in the area run loose in this area in the summer after lambing, like they do on our Moorlands here. Then they are brought down in autumn, sorted out and each farmer then supervises the “Tupping” in enclosed areas to make sure his Rams cover His ewes only?

      3. Exactly. The sheep live more or less wild for the summer and are herded and sorted in the fall. In Iceland this is called “réttir”, and is done by alle the farmes of one area together. Its always some kind of spectacle and a good reason to party together afterwards. Sorting is usually done on the weekend, by the herding is done in the week before.

  17. IMO seismologists still haven’t reviewed earthquakes (as circles on the maps they have light gray borders instead of dark gray). I guess that even more earthquakes will be added when they’ll start to.

  18. I also believe that present activity will lead to another flood and that it is basically hydrothermal.
    But that doesn’t rule out the fact that the whole system is getting destabilized and an eruption will follow. And also think that it could take longer than it took for Eyjafjallajökull, but this is sheer amateur’s hunch.

    1. I can verify the extreme weather in the UK; very heavy rain and high winds even here in London.

  19. Katla is really rocking and rolling this morning. I’m still convinced that we will see an eruption this year.

    1. Jón, no intention to disturb your nap, but I think we are at the verge of a new flood event, but for an eruption, still a long way to go.
      BTW Erik has a new post about Katla and he quotes you. 🙂

  20. This gives me the creeps…
    I just looked at the quake-swarm and found something that made me hick-up when I analyzed it.
    First, I removed all quakes below 1.0m, then I removed (temporarilly the 1,1km quakes)
    12 is the number of quakes higher up then 2,6 km.
    3 is the number of quakes deeper than 4,5 with the deepes at 5,7)

    Now to the 1,1km quakes. There are a total of 7, and 5 of them are not recalculated. So most of those five will probably be shallow to.

    What does this mean? Well, the buld of quakes are above the magma-reservoir that lies between 4,5 and 2,6 (most probable location since it is a dead zone, and as we know dead zones and magma–reservoirs do not quake.
    So, why all the shallow quakes? Stefan think it is ice-quakes, but no it is most likely not that. I think it is the roof above the magma-reservoir that has started to fracture, or to use the correct term, blocking. Blocking is when mountain strain or pressure makes the roof above cavities start to have fractures and fall down. When this happens in a volcano it can be a sign of magma pushing upwards, or that the magma is cooling. The cooling part we can just take out of the equation in this case.
    If I am right, and this continues for a while, the roof ontop of the chamber will fall down into the magma reservoir and this will happen…

    Image from a blocking ontop of the Kaptensgruvan in Malmberget. Yes it is swallowing the entire city.
    You can probably imagine what happens when this happens ontop of a volcano.

    If this continues for a week or so I will scale back my my prognosis of when Katla will erupt. I am still though keaping to my 3 – 123 months prediction sofar.

    1. “Stefan think it is ice-quakes, but no it is most likely not that. I think it is the roof above the magma-reservoir that has started to fracture, or to use the correct term, blocking. ”

      You missunderstood me. What i said is, that i believe the quakes are caused by the hydrothermal system. Which means: More Heat from the Magmachamber is making its way up, where it leads to an expansion of the hydrothermal fluid, which then most likely becomes steam. The Steam itself and the Overpressure it creates inside the Bedrock lead to Thermal Fracturing, which we can see. (All those Low Magnitude Quakes)

Comments are closed.