On the Origin of a Permafrost Vent on Yamal Peninsula, Russia

In my recent post on temperature history around Moscow, Alexander posted a link to a vent in Siberian permafrost that sparked some interesting discussion. Syndroma followed up with a link to a paper that described the feature. I have two motives for writing this post. The first is to describe some aspects of the geology of this area and the vent which I find to be quite extraordinary. And the second is to highlight some commentaters’ obsession with seeking to explain all natural phenomena such as this one by anthropogenic global warming and to block out all other explanations no matter how plausible they may be. Unfortunately this extends to the authors of the paper (p68) (Marina O. Leibman, Alexander I. Kizyakov, Andrei V. Plekhanov, Irina D. Streletskaya [1]) who provide much useful descriptive detail but exclude what I consider to be the most likely origin using a false pretext.

What lies behind the formation of this recent vent in permafrost on the Yamal Peninsula? Is it the result of methane ice clathrates melting in the permafrost? Or is it the result of a natural blowout from natural gas deposits below the permafrost?

Let me begin by making a number of key observations.

Location

The location of the vent is given as 69.58N and 68.22E. Zooming in on this on Google Earth yields the image below.

Figure 1 Click on all images to enlarge, note scale bar and coordinates at centre of image. Eye altitude 2.65km centred on the given coordinates. I can’t be certain this is the feature, it seems to be a bit too large and the coordinates for it are not exactly correct. Imagery date is 4th October 2013 and pre-dates the preferred date for the vent in question. If it is not the vent in question then it looks very like it, suggesting there may now be two or even three?

Figure 2 If we zoom out to 35.6 km, the vent is in the middle of the image, we see there are hundreds of small and large circular lakes in this area. I don’t believe all of these have formed the same way, many are likely to be subsidence features. But many of the small circular lakes look like they could have similar origins to the vent in question. There are hundreds of them.

Figure 3 Zooming out to 139 km eye height we see that the Yamal is totally pock marked with circular lakes of all sizes and that river courses prefer these lines of weakness.

Climate

The temperature history for two nearby climate stations (Salehard and Ostrov Dikson) have a temperature history typical of the Arctic comprising a warming leg from 1900 to 1940s followed by a cooling leg to 1970s followed by a warming leg to the present day. The 1940s were typically as warm if not warmer than the present day, not mentioned by Leibman et al. [1]

Figure 4 GHCN V2 temperature records for Salehard as reported by NASA GISS.

Figure 5 GHCN V2 temperature records for Ostrov Dikson as reported by NASA GISS.

Figure 6 The extraordinary thing about Siberian climate is the huge temperature swings between summer and winter. Temperatures below -20˚ in DJF are as cold as Antarctica. Temperatures above 10˚C in JA are close to those achieved in Scotland. The impact of summer warming is to turn the surface to mush but this does not normally mobilise more than the top 1 to 2 m, which then freezes solid again the following winter.

Geomorphology

There are two main features associated with this crater 1) a vent 25 to 55 m across and 2) material ejected from the vent referred to by Liebman et al [1] as the parapet that forms a ring around the vent about 70 m wide (Figure 7). There seems little doubt from the morphology that the feature has been formed by an eruptive process.

Liebman et al [1] make some key and interesting observations:

The volume of the parapet is approximately 2000 m3. At the same time, the volume of the void inside the hole is no less than 25,000 m3, which is more than 10 times the volume of the parapet. The difference is due to high ice content observed in the crater walls and constituting more than 80 % according to estimate at a glance.

and

The region is in the zone of continuous permafrost at least 300 m thick, with high tabular ground ice content.

Figure 7 The vent has many features similar to a volcano. A central vent surrounded by debris ejected from it that forms the parapet. Initially the parapet will have been much larger (taller) and made up of ice blocks that have subsequently melted.

We are in fact dealing with a substantial ice sheet. The elevation of the area is about 30 m above sea level, hence much of this ice sheet lies below sea level and presumably beyond the shores of the peninsula the ice sheet continues below the sea floor.

The small amount of debris compared to the volume of the vent shows that it was formed either by the eruption of gas or water. We now have enough information to piece together a jigsaw. Immediately post-eruption, the volume of debris, mainly ice, will have been much larger than we see today with a substantial volcano like cone around the vent. In summer the temperatures rise briefly and substantially above zero (Figure 6) and the ice melted giving rise to the melt water runnels that scar the icy walls of the vent.

Liebman et al [1] describe how the feature is rapidly collapsing due to melting. Melting of the vent walls is widening the vent with consequent collapse of silty debris into it. The parapet is being consumed as the vent widens. The hole is steadily filling with debris (mud and silt) and water and soon all that will be left is an irregular circular lake.

The Yamal peninsula forms part of the West Siberian natural gas province with some of the worlds biggest gas fields. The giant Bovanenko gas field lies beneath Yamal feeding gas to the Nordstream pipeline and northern Germany. The whole area will likely be underlain by mature natural gas source rocks producing gas 24/7/365 at depths of 10,000 to 15,000 ft and temperatures in excess of 100˚C. Globally, much of this gas seeps to surface where it escapes into the atmosphere continuously. Some of it gets trapped in sub-surface features that become gas fields.

It is established that permafrost prevents the migration of methane from deep-seated hydrocarbon collectors into the upper permafrost and to the surface. [1]

Thus, the impermeable ice layer prevents the escape of this leaking gas that presumably ponds in structures beneath the ice forming shallow reservoirs. Shallow gas accumulations and gas chimneys are common features above oil and gas fields.

Depth

The depth of the hole could not be accurately measured but it exceeds the 50 m to which the rope was lowered and was possibly around 70 m on July 16 and much less (no more than 35 m) on August 25. The depth is changing as the crater fills with mud, turf and water from the thawing permafrost. [1]

This is a crucial observation. The depth on July 16th was unknown but estimated to be about 70m. By August 25th thawing of the vent and in fill from the parapet had reduced the depth by 35 m in little over a month. Clearly the initial depth must have been significantly in excess of 70 m.

Discussion

There are two potential sources for the gas effusion responsible for forming this vent. The first is gas sourced within the ice itself and the second is thermal gas originating far below the ice that ponded beneath the ice sheet. Liebman et al. [1] do not consider this latter possibility at all. All they do is discount this option based on the following:

As water accumulates at the bottom of the hole, the feature has no access to deeper layers and the assumption that deep-seated gas deposits caused the crater is implausible. [1]

This assertion has no credibility and it is surprising it made it through peer review. The authors describe how the vent began to fill with silt and mud and this would quickly seal off flow through any conduit to permeable strata beneath the ice that might once have existed. The vent could then quite easily begin to fill with water that as observed froze, providing a further seal. The fact that the vent is filling with water provides zero evidence against the possibility that it penetrates all the way through the ice to tap a shallow gas reservoir ponded beneath it.

Figure 8 Crater Lake Oregon fills a collapsed volcanic vent (caldera) in Oregon. There is no doubt that the original volcanic vent tapped a magma source deep within the Earth’s crust. Subsequent collapse of the structure sealed off the conduits that once allowed gas and magma to easily flow to surface.

This of course provides no evidence to support the notion that the gas had a deep, thermal origin, but it does raise a question in my mind as to the motives for wanting to discount it. Following their logic, volcanoes could not form crater lakes.

Leibman et al. advocate an origin for the vented gas from within the ice citing a warm 2012 summer as the trigger for the event. This is also somewhat of a mystery for me. With a minimum depth of the vent set at 70 m I know of no conceivable process that could trigger clathrate to melt over 70 m down in an ice pack as the result of a few months of anomalous warm weather one summer (Figure 6).

The origin of this crater is attributed to the anomalously warm summer of 2012, the increased ground temperature and amount of unfrozen water in the permafrost, expanding of cryopegs, formation of a pingo-like mound and its outburst due to high pressure produced by gas hydrate decomposition within permafrost. [1]

This bears all the hallmarks of Greenscience which is disappointing to see from Russian scientists that I had hoped may have avoided this particular curse. The paper is published in a journal called Geography Environment Sustainability.

With the available evidence, it is in fact not possible to draw a firm conclusion about the origin of this vent. I am drawn more to the possibility that vent is the result of a natural gas blow out for a number of reasons. First there is a very high concentration of these circular vent-like features on Yamal that is known to be underlain by giant natural gas fields. Second, natural gas ponded beneath the ice could provide the energy and flow to create a blowout feature such as this. And third deep sourced natural gas may transfer heat towards the surface and this heat may help cause a weakness in the ice allowing the gas to escape to surface.

If the gas has origins within the ice then it would be necessary to invoke mobilization of a laterally continuous gas rich layer in order to muster sufficient gas and energy to form the feature. And the question remains as to why super cooled mobilized gas should elect to punch its way vertically to surface through a circular vent. A more normal behaviour would be for gas to migrate up dip through the mobilized layer until it met a fracture (fault) that would provide a pre-existing conduit to surface. Even if the gas does have an origin within the ice, I do not believe it is possible to conclusively link this to anthropogenic global warming or a warm 2012 summer.

If the vented gas had a deep origin then it will be long gone. High methane concentrations in the vicinity of the vent today will clearly have an origin from within the ice melting around the vent. Hence, compositional analysis of the gas there today will tell nothing about the source of the vented gas.

We live in a world where every weather, climatic or environmental feature is explained by anthropogenic global warming. Observations are made and workers decide how best to concoct a story that fits with the AGW story line. This is not science.

Proving the hypothesis presented in the paper would require a full range of field, laboratory and remote-sensing studies. [1]

Nor is this.

[1] Marina O. Leibman, Alexander I. Kizyakov, Andrei V. Plekhanov, Irina D. Streletskaya (2014) NEW PERMAFROST FEATURE – DEEP CRATER IN CENTRAL YAMAL (WEST SIBERIA, RUSSIA) AS A RESPONSE TO LOCAL CLIMATE FLUCTUATIONS: GEOGRAPHY ENVIRONMENT SUSTAINABILITY no 4 volume 7, p 68.

http://www.rgo.ru/sites/default/files/gi214_sverka.pdf

[Note added 11 th April: In comments Roger Andrews presents a compelling argument that this feature is in fact a sink hole and this has become my preferred explanation. The model would involve the collapse of a cylindrical body of ice and frozen clay into a water or gas filled void beneath. This would cause the displacement of fluids upwards through the “vent” creating the eruptive features associated with the parapet. The main weakness of this explanation lies in the creation of a large fluid filled void beneath the surface ice into which the cylindrical plug of permafrost collapsed.]

 

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21 Responses to On the Origin of a Permafrost Vent on Yamal Peninsula, Russia

  1. Hugh Sharman says:

    Good stuff! Learned and readable! I also found the Liebman et al.AGW explanation unconvincing but we need Euan to expose the likely fallacy in their argument. Euan for the post-election energy minister, please

  2. TomL says:

    I have heard that much (most?) of the Yamal methane is biogenic, not thermogenic, and could have a shallower origin than several km. This doesn’t affect your conclusions, except that it potentially places a large-volume methane source nearer to the surface than the Bazhenov shale.

    • Euan Mearns says:

      Tom, I’m sure there is loads of biogenic methane in this environment, and to be honest I never considered the possibility that the giant gas fields may have a biogenic origin. But this wikipedia source describes gas, condensate and oil fields showing that at least there is a functioning thermal petroleum system.

      http://en.wikipedia.org/wiki/Yamal_project

      One peculiar aspect of this terrain is that summer comes first to the snow covered areas to the south that melts sending large volumes of melt water northwards that then freezes where it is still winter. It seems likely this is implicated in the formation of this kind of ice sheet that incorporates sediments, organic matter and ice.

  3. Syndroma says:

    A few points.
    Yamal is being actively developed for the last 10-15 years. Railways, helicopters all around. And nobody ever noticed anything like this crater. Yes, there’re circular lakes in the area, but nobody saw a fresh crater. Something had to trigger it now. Of course, it could be a random event, but if the reports of other craters are confirmed, then it’d be an unlikely coincidence.

    Map of the craters:
    http://www.planet-nwes.ru/wp-content/uploads/Optimized-otverstie-yamal-2.jpg

    More photos:
    http://www.planet-nwes.ru/desyatki-novyh-otverstij-obnaruzhili-na-yamale/

    New expeditions this summer should provide some interesting observations.

  4. The Yamal “crater” is a vertical cylinder with a diameter of 25m. It’s been plumbed to depths of 70m but could originally have been deeper, so let’s assume it was originally 100m deep. That gives us a void volume of 50,000 cubic meters.

    According to the paper by Liebman the crater was formed by a gas explosion:

    The origin of this crater is attributed to the anomalously warm summer of 2012, the increased ground temperature and amount of unfrozen water in the permafrost, expanding of cryopegs (liquid brine lenses), formation of a pingo-like mound and its outburst due to high pressure produced by gas hydrate decomposition within permafrost.

    Increasing ground temperatures in the last decade, particularly in 2012, could have released gas both out of permafrost and bubbly facies of tabular ground ice, as well as from decay of gas hydrates. The last gives a large cataclysmic expansion. This expansion which may start from a slow process produces a landform close to the one known as pingo (hydrolaccolith). This form will serve as a limitation factor for localization of the future hole and determine its cylinder shape. In time as gas hydrate decomposition acquires its full strength, the “shot” pops up the frozen ground cover.

    There are, however, problems with the gas explosion hypothesis. I checked into how much explosive power would be needed for an explosion occurring at a the base of the crater, i.e. at around 100m depth, to breach the surface, and according to the underground nuclear test formula Depth in feet = 400 (yield in kilotons) ^1/3 it’s about two kilotons, which is a lot to ask of a pressurized gas pocket.

    Liebman et al. claim that the pingo-type hill that existed before the formation of the crater determined the cylinder shape of the hole, and since pingos are thought to be underlain by pipelike bodies of unfrozen ground called taliks we can assume that a pre-existing zone of structural weakness was indeed present:

    But for a gas explosion to pop an almost perfectly circular cylinder of material cleanly out of the ground, like a cork out of a champagne bottle, still strains credibility. Rocks and earth, and I suspect permafrost too, just don’t react to explosions that way. I lowered a lot of explosives down shot holes doing seismic surveys in my early career and never once succeeded in blowing a smooth-sided cylindrical hole in anything. And the explosive power needed to blow 50,000 cu m of material a hundred meters or more into the air is still very large even in the absence of frictional resistance. And how is it possible for an explosion this powerful to leave the sidewalls of the cylinder smooth and undisturbed?

    As I said, there are problems with Liebman et al’s gas explosion theory.

    So we must look for alternative explanations. What other possibilities are there? One obvious one is that the Yamal crater is a sinkhole. Except for the urban surroundings it’s almost identical to the sinkhole that suddenly appeared in Guatemala City in 2010 – same width, similar depth and a near-perfect cylinder with smooth and undisturbed sidewalls. There are countless other sinkholes elsewhere in the world that show similar features. So what are the objections to calling Yamal a sinkhole?

    First, a sinkhole needs a cavity to collapse into, most usually a subterranean cavern in limestone. But we can in fact explain how one might form at Yamal. As shown in the pingo section above, below the pingo ice is a talik, which is unfrozen material with groundwater moving through it. But it was once permafrost, containing a high percentage of ice, and now there is no ice. The result is a water-filled cavity, plus maybe some pressurized gas released from the melted permafrost.

    The second and more problematic objection is that the Yamal crater is surrounded by ejected debris, which is not characteristic of a sinkhole. Where did this debris come from? Explaining this is not as easy as explaining how a cavity might have originated below the Yamal cylinder, but the following mechanism broadly fits the facts.

    Sinkholes often develop very rapidly – so rapidly in some cases that they swallow not only roads, trees and buildings but also livestock, moving vehicles and people. So let’s assume that at Yamal 50,000 cu m of material collapsed abruptly into a subterranean water-filled void. Suddenly 50,000 cu m of displaced water had to go somewhere, and the only place it could go was up into the void formed by the collapse. So it moved upwards through the void, we will assume with enough violence to overtop the rim when it reached the surface.

    One problem with this theory is of course that the density of the collapsing cylinder, which has a high ice fraction, would not be much greater than that of the water it displaces, which would limit the rate of displacement. As shown in the photo below, however, there is clear evidence for water movement at the top of the cylinder. The vertical cylinder wall on the right is very smooth. It almost looks as if it’s been plastered with mud. Well, it has. And those curious patterns on the left cylinder wall are ripple marks, caused by water flow: Which way was the water going? The marks extend to within about five meters of the original ground surface and there’s no record of there having been a lake here – according to Liebmann et al there was in fact a hill – so it must have been going upwards:

    Note also how the cylinder opens up in the top five meters. This is not an erosional feature – the Yamal event is too recent for that (according to Liebman it’s only about a year old). It originated at the time of cylinder formation, probably as a result of near-surface pressure release. It is in fact the only feature of the Yamal “crater” that actually qualifies as a crater in the accepted sense of the word.

    The question of volume now becomes significant. Liebman et al. state that there is only about 2,000 cu m of debris on the surface, less than 10% of the 25,000 cu m they estimate to be the minimum volume of the cylinder and less than 5% of my 50,000 cu m estimate. Where did the rest of the material allegedly ejected from the cylinder go? Well, they say, it was more than 80% ice – it melted. And maybe it did. But about 15,000 cu m of material was originally present in the near-surface crater and the debris contains a high proportion of soil plus fragments of turf. Assuming 80% ice melt leaves us with 3,000 cu m, and we can assume that some of this fell back down the hole, so we have a balance. Moreover, the near-surface crater is the only obvious “vent” feature at Yamal. We can therefore assume that all the debris came out of the ~5m deep crater above the cylinder. We need no contribution from the cylinder itself.

    This close-up photo of one of the debris heaps is also revealing (the empty bottle on top gives the scale). It shows a soil horizon (full of roots) overlying fractured bedrock. What we are looking at is material torn off the top of the crater that was carried sideways and redeposited on the crater rim the right way up and relatively intact. Violent explosions don’t usually achieve results like this. More likely the material was carried in there by water.

    To summarize, here’s the sequence of events at Yamal as I interpret them:

    1. Formation of a pingo structure

    2. Development of a water-filled cavity in the underlying talik.

    3. Collapse of a cylindrical mass of material into the cavity.

    4. Displaced water from the cavity flows up the open cylinder, possibly accelerated by pressurized gas, and vents through the surface cap.

    5. The remains of the surface cap are left as debris around the “crater”.

    • Euan Mearns says:

      Roger, I certainly will not dismiss this hypothesis. I have recent experience of a loose wine cork disappearing into a bottle when pressure was applied by cork screw resulting in wine in my face and on the ceiling. But a few issues need to be addressed.

      1) The sink hole in Guatemala City is at an altitude of 1500 m. Loads of gravitational potential energy to create this feature in an area that is seismically active.

      2) The Guatemala City sink hole ejected nothing. It seems to have sunk into an empty cavern – possible at this altitude.

      3) In Yamal there doesn’t seem to be the relief to create a hydraulic head to create Talik (though I’ve not checked this in detail).

      4) In Yamal there seems to be a problem with gravity and potential energy. Ice is not going to collapse vertically into water.

      I agree that the math of what is left on surface as “parapet” compared with volume of vent is highly dubious. And I have to admit that I don’t really like any gas eruptive theory but I prefer a sub-permafrost blowout theory to an intra-permafrost burp theory.

      The truth may lie somewhere between the two end members of blowout and sinkhole.

      • The sink hole in Guatemala City is at an altitude of 1500 m. Loads of gravitational potential energy to create this feature in an area that is seismically active.

        Gravity works regardless of altitude. It’s actually slightly stronger at sea level than at 1500m.

        The Guatemala City sink hole .. seems to have sunk into an empty cavern – possible at this altitude.

        Again elevation doesn’t matter. Florida is one of the world’s sinkhole capitals.

        In Yamal there doesn’t seem to be the relief to create a hydraulic head to create Talik.

        You don’t need relief, or at least not in the topographic sense 😉 . A hydrostatic head would force groundwater below the permafrost up into any weaknesses in the permafrost.

        Ice is not going to collapse vertically into water.

        I agree this is a problem. Do you have any info on permafrost densities? I can’t find any.

        • Euan Mearns says:

          Roger, my reference to altitude was to make the point that in Guatemala there was elevation for a sink hole to drop hundreds of feet into a void. On Yamal there is not.

          But part of the key here can lie in the assumption that the feature is eruptive. That forms the basis for the dodgy calculation linking debris in parapet to size of the hole. If the hole is formed by subsidence then all bets are off regarding the ice content and density.

          If the hole is formed by subsidence then the walls need either to be cylindrical or widen downwards. Looking at some of the pics posted by Syndroma this does indeed appear to be the case. If it has formed by subsidence then my wine bottle cork analogy is worth thinking about. The plug would have to subside into a fluid filled cavern and a volume of sludge equivalent to the volume of the subsided plug would erupt out of the “vent” giving rise to the parapet and eruptive features.

          Arranging for a fluid filled cavern remains a physical problem. But I wonder if over-pressure may have something to do with this. If there are permeable layers within the ice that are pressure sealed then the system may respond like a hydraulic system. Apply pressure at one part by say differential loading may create over-pressure in another part of the system. If that other part of the system is at shallower level the over pressure may be sufficient to support the weight of over-burden. Or perhaps there are tunnels in the ice with rivers flowing through them?

          • JerryC says:

            Florida sinkholes can be quite deep despite being at sea level. That’s all limestone, though, so it’s a relatively simple and well understood process. Limestone is porous so when groundwater gets depleted, it loses its strength and collapses straight down. Yamal geology seems a lot more complicared with all this ice and gas and extreme freeze-thaw cycles in play.

          • Roger Andrews says:

            Euan: My comments on your comments.

            my reference to altitude was to make the point that in Guatemala there was elevation for a sink hole to drop hundreds of feet into a void. On Yamal there is not.

            Here’s a landscape that will strike you as familiar.

            Except that it’s not Siberia. It’s Avon Park, Florida. Each one of those round lakes is a sinkhole.

            You even get sinkholes under the sea. Here’s the world’s deepest: Dean’s Blue Hole in the Bahamas, depth 663 feet.

            But part of the key here can lie in the assumption that the feature is eruptive. That forms the basis for the dodgy calculation linking debris in parapet to size of the hole.

            As Sherlock Holmes was fond of saying, once you have eliminated the impossible, whatever remains, no matter how improbable, must be the truth. The vertical cylinder below the surface crater at Yamal exhibits all of the features of a collapse and none of the features of an eruption. Therefore I eliminate an eruptive origin as impossible.

            If the hole is formed by subsidence then the walls need either to be cylindrical or widen downwards. Looking at some of the pics posted by Syndroma this does indeed appear to be the case. If it has formed by subsidence then my wine bottle cork analogy is worth thinking about. The plug would have to subside into a fluid filled cavern and a volume of sludge equivalent to the volume of the subsided plug would erupt out of the “vent” giving rise to the parapet and eruptive features.

            That’s my theory too. 🙂

            If the hole is formed by subsidence then all bets are off regarding the ice content and density.

            It occurs to me that if the area was underlain by ice-free talik material then at least some of the collapsed cylinder would be ice-free rock with a density of – what? Looking at the rock below the soil horizon in the photo I posted in my first comment I would guess 2.5 g/cc. That would certainly make a splash.

            Arranging for a fluid filled cavern remains a physical problem. But I wonder if over-pressure may have something to do with this.

            I don’t think we need overpressure. We can do it simply by having percolating groundwater under a hydrostatic head melt or wash out the ice at the base of the permafrost layer in much the same way as it dissolves limestone in karst terrain.

            Or perhaps there are tunnels in the ice with rivers flowing through them?

            I don’t think we can dismiss the possibility.

    • Syndroma says:

      Not all of the volume must be a dense matter. Significant part of it could be a void filled with pressurized gas. The bigger the void, the lesser pressure is required.

  5. Euan Mearns says:

    http://www.gazprom.com/about/production/projects/deposits/bm/

    Some great pics here of what must be one of the flattest places on Earth. Hydraulic pressure normally requires a head.

  6. Euan Mearns says:

    Before responding to Roger, a pic from yesterday, 8th April 2015. Skiing on Aonach Mòr. Ben Nevis in background.

  7. Readers may be interested in an email released under the Climategate event.

    I inserted *** asterisks *** to draw attention to the relevant statement.

    The leaked e-mails show that the Russian researcher who collected the tree-ring data observed that the trees line had not moved north as would be expected if climate warming had occurred. I attach an excerpt from the leaked e-mail (document 907975032.txt):

    Quote

    From: Rashit Hantemirov
    To: Keith Briffa
    Subject: Short report on progress in Yamal work
    Date: Fri, 9 Oct 1998 19:17:12 +0500

    Dear Keith,

    I apologize for delay with reply. Below is short information about state of Yamal work. Samples from 2,172 subfossil larches (appr. 95% of all samples), spruces (5%) and birches (solitary finding) have been collected within a region centered on about 67030’N, 70000’E at the southern part of Yamal Peninsula. All of them have been measured.

    [SNIP except for the last sentence]

    *** There are no evidences of moving polar timberline to the north during last century.***

    Rashit Hantemirov, Lab. of Dendrochronology, Institute of Plant and Animal Ecology,
    8 Marta St., 202 Ekaterinburg, 620144, Russia.

    End of Quote

  8. TomL says:

    Decomposition of clathrate is an endothermic process so it’s damn near impossible to envision how it could occur explosively. You would have to dump a lot of heat into it very fast. Either that or it happened gradually but was contained by a seal capable of holding back high pressure, also highly unlikely within tens of meters of the surface.
    One way you might release a lot of gas fast would be to collapse clathrate-filled permafrost into a large volume of liquid water. That might bubble out fast enough to eject material from the hole.

    • Tom L: Do you have any idea what kind of pressures might be generated in pockets of methane released from clathrates and trapped below a permafrost layer?

  9. Here’s an interesting close-up from the Liebman report. It shows a band of tabular ground ice at the contact between the vertical cylinder and the shallow “blowout” crater.

    You can see this ice layer exposed in places at the cylinder/crater contact in the larger photo:

    The fact that the shallow “vent” crater begins at the base of this ice layer suggests that the ice formed a caprock that blew under increasing pressure from below.

    Then there’s the clay below the ice layer. It looks solid. No visible ice content. Density maybe 2.2 g/cc?

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