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Drone flies inside giant Yamal permafrost crater for first time, dipping 15 metres below the surface

By Anna Liesowska
25 February 2021

Underground aerial survey throws important new light on these eerie giant holes, enabling a first 3D model.

First-ever 3D model of the newest permafrost heaving mound that exploded in summer 2020 on the Yamal peninsula. Picture: Vasily Bogoyavlensky

Some 20 large craters have formed in recent years after explosions of bulging mounds in areas of the Russian Arctic. The cause is believed to be a build up of methane gas triggering blowouts which send ice and frost soil hundreds of metres from the epicentre.

In summer 2020, researchers from the Oil and Gas Research Institute (OGRI) of the Russian Academy of Sciences and colleagues from Skolkovo Institute of Science and Technology (Skoltech) surveyed the newest known 30-metre deep gas blowout crater on the Yamal Peninsula, formed in summer 2020.

It was vital to get to it quickly because these holes rapidly fill with water, becoming lakes pockmarking the surface.

Yamal craters



3D model of the surface and the underground cavity. Picture by Vasily Bogoyavlensky; videos of the newest-exploded (summer 2020) permafrost heaving mound by Igor Bogoyavlensky from air/drone and Yevgeny Chuvilin/Skoltech from land


A key finding appears to be that the scientists identified two gas filled cavities inside the bulging mound which merged into one, and then exploded. Expedition leader Professor Vasily Bogoyavlensky, OGRI deputy director, said: ‘This ‘underground aerial survey’ of the C17 crater was the most difficult task I had ever faced in the Arctic.’ 

It involved the scientist - also a certified pilot – Igor Bogoyavlensky ‘having to lie down on the edge of a 10-storey deep crater and dangle down his arms to control the drone.

Igor said - ‘Three times we got close to losing it, but succeeded in getting the data for the 3D model.’

They got some 80 drone images from the 30 metres deep crater. 

Yamal craters


Yamal craters


Yamal craters


Yamal craters

Aerial photograph of the C17 crater, and pictures of its grottoes taken from inside the crater. Pictures: Igor Bogoyavlensky


Professor Bogoyavlensky said: ‘We could not see everything from above, especially the grottos, possible caverns in the lower part of the crater. You can clearly see all that with the 3D model. 

‘Our results suggest unequivocally that the crater was formed endogenously, with ice melting, a heaving mound dynamically growing due to gas accumulation and the explosion.’

The researchers used the data to build a 3D model based on the unique drone images from inside the crater. 

They were able to monitor a well-preserved oblong ice cavity where gas had been accumulating. 

As they reported in Geosciences Journal their evidence indicates that ‘initially not one but at least two cavities were formed in the massive ice. 

‘As their size increased, these cavities merged into a single underground space with an elliptical bottom.’

Yamal craters


Yamal craters

C-17 Yamal gas blowout crater: 3D model of the surface and the underground cavity. Picture: Vasily Bogoyavlensky. Closer look at the structure of the C-17 crater walls pictured by Vasily Bogoyavlensky, Roman Nikonov, Evgeniy Chuvilin


Dr Bogoyavlensky estimated the volume of the merged cavity was 7500 cubic metres.

‘At a pressure of about 15-20 atmospheres, this gives us approximately 112,000-150,000 cubic metres.’

He said: ‘We got there in time to find the object in its almost pristine state, with no water filling it.

‘Secondly, the giant underground cavity in the ice is unique in itself. 

‘A part of the icy dome of this cavity was preserved.

‘Before the explosion, it had this circular dome, and its bottom was elliptical, elongated to the north, with its axis ratio of approximately 1 to 4.5. 

‘From what we know we can say that the C17 crater is linked to a deep fault and an anomalous terrestrial heat flow.’

Yamal craters

Aerial photograph of the C17 crater from the height of 50 m above sea level. Picture: Igor Bogoyavlensky


This suggests that the reason for this eruption lay in part, at least, deeper than methane accumulating close to the surface due to a recent thawing of the upper layers of permafrost. 

The 3D models permitted the scientists to map the complex and intriguing shape of the underground cavity which appears to have formed between 15 May and 9 June 2020. 

It was seen for the first time from a helicopter on 16 July. 

This is a time of year when snow melts and the upper layers of the ground heat. It is an additional important factor in at least some of the explosions, it is believed. 

Skoltech researchers were able to study the cryo geological conditions of the crater along with the composition of permafrost.

They examined the material ejected from the crater and  temperature conditions on the hole’s floor.

Yamal crater
Aerial image from of the exploded mound, orthophotomap and digital elevation model in the area of C17 crater. Picture: Igor Bogoyavlensky


‘This information will shed light on the conditions and formation of these unusual objects in the Arctic,’ said  Dr Evgeny Chuvilin, leading research scientist at Skoltech.

‘The new crater is impressive in its ideal state of preservation, primarily the cone-shaped top where ejecta was thrown from (and) the outer parts of the heaving mound that precipitated the crater.’

The walls were ‘incredibly well preserved’ as was the gas cavity in the icy bottom of the crater.

Dr Bogoyavlensky and his team have identified in the Yamal peninsula over 7,185 bulging Arctic heave mounds, part of which has risk of exploding in a region which includes natural gas reserves vital for supplies in Europe. 'Five to ten per cent of these 7,185 mounds are really dangerous,' said the professor. 

Russia’s state-of-the-art Sabetta liquified natural gas exporting port is among the places threatened by the 'ticking time gas bombs'.

Dr Bogoyavlensky called for more urgent monitoring of the so-called heave mounds onshore and offshore.

Comments (2)

I think it's just a pressure buildup eruption, not an ignited explosion. Whatever they are, they certainly are fascinating. I don't know of any features like this in Alaska.
Richard Flanders, Fairbanks, USA
06/03/2021 20:12
2
0
Its a very interesting question where the heat comes from which warmed up the water. Hydrothermal oroging?
Tillmann, Germany
01/03/2021 00:47
4
0
1

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