As reported by the Siberian Times, craters in the Yamal peninsula, which number in the thousands, have been spotted engaging in a bit of violence. This isn’t just based on the formation of seemingly new craters, however. In-crater explosions, ones that are creating fresh in-crater scars, are also now apparently taking place, based on new satellite imagery.
So what’s causing these craters and their internal explosions? What certainly isn’t to blame are meteorite impacts, military tests, or (sigh) aliens, but it’s definitely nothing gradual. The craters are indubitably explosive remnants, as evidenced by the concentric debris scattered around them.
It’s clearly got something to do with what’s happening beneath the surface, and two hypotheses rule the roost at present: methane blasts and the self-destruction of pingos.
The nature of the region’s permafrost – frozen soil that remains that way for at least two consecutive years – is itself deeply enigmatic, but we do know that it contains a lot of organic matter.
Although it’s unclear how much is there, this grim menagerie of dead plants and animals is certainly sizable. As the region warms due to anthropogenic climate change, the permafrost’s namesake begins to look a bit shaky as it starts to thaw. As it does so, microbes within the soil drive the now-freed organic matters’ decomposition, which produces carbon dioxide and, mostly, methane gas.
Methane may not linger in the atmosphere for more than a dozen years or so – unlike carbon dioxide’s 20-200 year cumulative residence up there – but it is 34 times more effective at trapping heat within our atmosphere on a century timescale. This rises to a factor of 86 in the short term.
Understandably, climatologists are trying to determine the characteristics of any future methane releases. This is all deeply uncertain at present, but in any case, the currently observed methane release has been implicated in the formation of these craters too.
Some have suggested that methane pockets may be actively causing the formation of these craters when it explosively decompresses en masse. Post-formation, methane trapped below the crater floor by fresh debris may be causing repeats of these blasts.
But wait – what about those pingos?
Pingos – technically termed “hydrolaccoliths” – are dome-shaped hills formed in this chilly part of the world when groundwater is pushed up by an ice plug. Geologists have suspected that when these ice plugs rapidly thaw, they cause the pingos to collapse, forming a crater.
Satellite imagery seems to confirm that the new craters appear on the exact spots that these pingos explode, which suggests this is the winning hypothesis for how these craters form in the first place. However, there’s a final twist in the tale – it could, as pointed out by National Geographic, be both mechanisms conspiring together.
It’s not clear whether or not the sudden thawing of the plug is explosive enough to excavate a large crater. If the pingos trap escaping methane gas too, however, this pressurized natural bomb will eventually explode, generating a sizable hole in the ground.
This also implies that, as the planet continues to warm, we’ll get more craters up there. In fact, the planet was warming (far more gradually) prior to the Industrial Revolution, so perhaps these craters have been forming since the termination of the last glacial maximum.
In any case, as noted over at LiveScience, several researchers emphasize that this two-part formation process is still speculative; no one’s actually documented the process from start to finish. Considering we’ve only just discovered these formations in the past few years, it’s unclear how common or rare their apparent births and behaviors actually are.
For now, then, the jury is still out. We've reached out to a few geoscientists for additional comments.
