The mystery of the giant ‘potholes’ in the Siberian polar regions

Tram Ho

After a sudden explosion, on the ground in Yamal – a peninsula in northwestern Siberia Russia – left an unusual hole. At the edge of the pit is shattered rock, gray ice mixed with permafrost. The roots of the trees exposed to the edge of this giant pothole show signs of burning. All of this tells us how these craters were formed.

Viewed from the air, the new layer of soil on the edge of the hole is particularly eye-catching in the midst of the green tundra and surrounding lakes. On closer inspection, you can see that the soil and rocks inside the cylindrical pit are almost black. When the scientist reached the cave entrance, a puddle formed on the bottom.

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Incredible “potholes” are popping up in the Arctic.

Evgeny Chuvilin was one of the first geologists to come here. He works at the Skolkovo Institute of Science and Technology in Moscow, Russia. And one of the mysteries that has stuck with him for the past six years is this crater about 50 meters deep. Ever since the first mysterious hole was discovered in another location on the Yamal peninsula, a mystery has been in his mind.

At that time, in 2014, the hole was about 20 meters wide and 52 meters deep was discovered in the sky by a helicopter pilot, about 42 kilometers from the Bovanenkovo ​​gas field on the Yamal peninsula.

Scientists visiting it described what they saw as “a whole new phenomenon in permafrost”. Subsequently, analysis of satellite images showed that the crater, now known as GEC-1, formed between October 9 and November 1, 2013. The last crater was seen in August this year. Thus, the total number of confirmed craters found in Yamal and the neighboring Gydan peninsula has risen to 17.

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Scientists from the Petroleum Affairs Institute of the Russian Academy of Sciences visited this newly discovered giant hole during an expedition to Yamal in August 2020.

However, what causes these giant craters to appear in permafrost and how they suddenly form remains a mystery. Their implications are especially important for the Arctic’s future, and this is arguably a worrying sign of fundamental changes underway in this cold and sparsely populated region north of the earth. .

Giant hole formed like?

However, recent studies have begun to provide some clues to the phenomenon. It is firmly established that the formation of these deep holes was not the result of permafrost melting and moving below the surface of the earth, then gradually sinking. Instead, their formation comes from explosions.

“When an explosion happens, large chunks of earth and ice will be thrown hundreds of meters away from the center of the explosion thanks to pressure. But why the pressure underground is so high remains a mystery,” said Yevgeny. Chuvirin said.

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To understand more about how giant pits form, scientists went deep into the pits to collect samples.

Yevgeny Chuvirin’s group of Russian scientists are collaborating with colleagues from around the world. They explored these giant holes, collected samples and measured data, in the hope of understanding more deeply about the tundra’s underground conditions.

Some scientists have compared these giant holes to ice volcanoes. Ice volcanoes exist on distant celestial bodies such as Pluto in Saturn’s solar system, moon, and the dwarf planet Ceres. They do not spit out lava but rather ice magma consisting of volatiles such as water, ammonia and methane. However, as more and more giant holes in the Arctic have been studied, they have become known as “gas release craters”. From this name, we can get some clues about how they are formed.

“Satellite-based analysis shows that an explosion occurred in what was originally a ping-pong ball (Pingo) or mound, forming a giant pothole,” said Yevgeny Chuvirin.

Pingo is an arched hill, also known as an icy hill. When a layer of frozen ground is emptied by the water flowing below it, then the water starts to freeze, the mound will expand to form an icy hill. Pingo tends to increase and decrease depending on the season. Some “hills” in Canada have been found around 1,200 years old. However, these hills tend to collapse on their own instead of exploding.

But these mounds in northwestern Siberia are very different. Yevgeny Chuvirin explained that they swell “very quickly and can be pushed up to several meters high”, then exploded. Furthermore, their being pushed up was not due to the freezing water, but rather the accumulation of gas underground.

“Ice mounds take decades to reach,” said Sue Natalie, an arctic ecologist, permafrost specialist and director of the Arctic Project at the Woodwell Center for Climate Research in the US. are formed and can last a long time. These gas mounds are formed within a few years. “

In the first giant hole discovered in 2014, scientists uncovered willow growth rings from the blast’s ruins. A study of these growth rings showed that these plants have been under pressure since the 1940s. Researchers say these pressures can come from deformation of the ground.

Alexander Kizyakov, a scientist at Lomonosov University in Moscow, Russia, said: “However, there is evidence that the life cycle of the gas emission sinks can be very short, from three to five years. The chimpanzee shows a giant hole called “SeYkhGEC” formed in the early summer of 2017 that began to deform the ground as early as 2015. “

The hills exploded

Similar scars and mounds related to the release of air sacs were found at the bottom of the Kara Sea, near the Yamal peninsula, while other “scars” were found in the Barents Sea. But so far no similar topography has been found on land elsewhere in the Arctic.

Researchers went down to the craters and noticed elevated levels of methane in the water that accumulated on the bottom, a sign that the methane might be coming from below. One theory is that methane gas buried deep under permafrost has found a way to rise up from the non-icy pits under the ice cap. Another point is that in these icy pits, when the water begins to freeze, the remaining water no longer holds the high concentration of dissolved carbon dioxide, and these gases begin to bubble.

Regardless of the source of the gas, the researchers basically believe that the gas will accumulate in the non-freezing pits, pushing the solid and flat ice cap 5 to 6 meters up until it flares up like a pot of water. boiling.

When these mounds finally exploded, the sight was truly spectacular. The soil and ice above the pit, along with most of the unchecked material, was thrown 300 meters away. This force is so great that a mass of earth 1m wide will be thrown out, leaving a large hole with a raised edge. The opening is wide open and below is a relatively narrow cylindrical hole.

Local reindeer breeders said they saw flames and smoke after a crater exploded in June 2017. Residents nearby – in a settlement about 33 kilometers south of the crater – reported the gas continued to burn for about 90 minutes, with the flames going as high as 4-5 meters.

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Natural gas and oil infrastructure is scattered throughout Northwest Siberia, and the Bovanenkovo ​​gas field (pictured) is only 42 kilometers from the first “pothole” discovered.

“We still don’t know if this could put the people of the Arctic at risk,” said the scientists.

Greater impact on Earth

Surface air temperatures in the Arctic are increasing twice as fast as the global average, increasing the amount of permafrost thawing during the summer months. This in and of itself is transforming the Arctic landscape, leading to subsidence and landslides caused by thawing.

Inside the arctic permafrost contains an enormous amount of carbon – more than twice as much carbon as present in the atmosphere. These are mainly frozen residues of plants and other organic matter, as well as methane, trapped inside ice crystals – gas hydrates. As the ice melts, microorganisms decompose organic matter, releasing methane and carbon dioxide as byproducts, and the methane trapped in the ice is released.

“As far as I know, there’s nowhere else on this planet that climate change could cause changes in the physical structure of the ground like this,” said Sue Natalie.

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The appearance of these giant holes is a very spectacular sight, as the explosion threw out mud and ice, leaving a deep cylindrical cavity.

And as a cycle, the methane leaking from the permafrost could accelerate global warming and thus cause further melting.

But in Yamal, craters offer the prospect of yet another process that even adds uncertainty to the complex feedback loop between rising temperatures, melting permafrost and greenhouse gas emissions. If the methane sediment trapped in the permafrost deep underground is beginning to seep through permafrost, it could be a sign that the ice cap on the tundra is becoming permeable. more penetrating. And this could create a new level of uncertainty as to how the changes in the Arctic could affect global warming on a larger scale, or even on the planet.

“These potholes are shocking signs of what’s going on in the Arctic. When you look at the changes that are going on in this area, you see that some are happening gradually, some are happening. Explosive change is rare, but these events raise concerns about how all of these changes will affect greenhouse gases in the atmosphere, “said Sue Natalie. added.

Although the mysteries of the “potholes” in Yamal are still being studied, the facts revealed so far suggest that these potholes are of great significance and that humans should observe them carefully. more in the future.

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Source : Genk