A massive crater suddenly appeared in the Siberian tundra last year, after a powerful explosion of methane gas that threw pieces of ice and rock tens of meters away, which left a circular "scar" in the empty and strange landscape.
"The last crater had not yet accumulated water, so we studied a 'fresh', undegraded crater," said Evgeny Chuvilin, a senior researcher at the Skolkovo Institute of Science and Technology in Moscow, according to CNN.
It was also the first time that researchers managed to lower a drone into the crater, at a depth of 10-15 meters, which allowed the study of the underground cavity in which methane accumulated.
Chuvilin was part of a team of Russian scientists who explored the crater in August 2020. Their findings were published in the journal Geosciences last week.
The drone took about 80 images, allowing researchers to produce a 3D replica of the crater, which is 30 meters deep.
The study's author, Igor Bogoyavlensky, from the Oil and Gas Research Institute, "piloted" the drone and said it was necessary to bend over the crater to control it. "Three times we were about to lose it, but we managed to get the data for the 3D model," he said.
The reproduction, which features unusual caves or caverns at the bottom of the crater, has largely confirmed what scientists have assumed: methane gas accumulates in the ice layer, causing a mound to form at ground level. The mound grows in size and then the explosion leaves behind the massive crater.
What is not known is the source of the methane. It could come from the lower layers of the Earth, from the surface or from both.
Permafrost is a huge natural reservoir of methane, a greenhouse gas much stronger than carbon dioxide. Warmer summers - the Arctic is warming twice as fast as the global average - have weakened the permafrost layer, which acts as a cover, facilitating gas evacuation. Some experts estimate that soils in the permafrost region contain twice as much carbon as the atmosphere, making the region extremely important in the fight against climate change.
"Climate change, of course, has an impact on the likelihood of craters in Arctic permafrost," Chuvilin said.
With the help of satellite images, the researchers were able to identify when the crater formed. They believe the mound exploded between May 15 and June 9, 2020. The crater was first seen during a helicopter flight on July 16, 2020.
The moment was not random, according to Chuvilin. "This is the time of year when there is a flow of solar energy that causes snow to melt and heat the upper layers of the soil and causes changes in their properties and behavior."
While these craters have appeared in a sparsely populated region, they pose risks to indigenous people and to oil and gas infrastructure. The holes are usually discovered accidentally, during helicopter flights or by reindeer herders.
Although 17 craters have been documented so far, it is not known how many there are in total or when the next one could appear.
Scientists do not yet have effective tools for detecting and mapping emission craters, although a team at the Woodwell Climate Research Center in Massachusetts is trying to do so.
To record changes in the Arctic landscape and probably eventually to predict where the next explosion crater might occur, the researchers devised an algorithm to quantify changes in soil characteristics, such as mound height and expansion or reduction of lakes. on the Yamal and Gyda peninsulas.
The formula correctly predicted all seven craters reported by scientists by 2017 and revealed the formation of three new ones.
Researchers have also discovered that these craters are just a disturbing sign that the northernmost areas of our planet are undergoing radical changes. About 5% of the 327,000 square kilometers studied underwent sudden changes in the landscape between 1984 and 2017. These changes include landslides, the formation of new lakes and the disappearance of others, plus the erosion of riverbeds, according to the study published in the journal
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