For the first time, geologists used an aerial drone to map the interior of a giant crater, which appeared with increasing regularity in Siberia.. The resulting 3D model, along with other data collected during the survey, claims the dominant theory that connects these bizarre holes in the tundra as the heat increases.
“Over the years I have gained a lot of experience with surveillance drones, however this underground aerial survey of the C17 crater was the most difficult task I have ever faced, having to lie on the edge of a 10-story deep crater and hangs on his arms to control the drone, “said Igor Bogoyavlensky, a geologist at the Petroleum and Gas Research Institute of the Russian Academy of Sciences. statement.
Bogoyavlensky said he was close to losing the drone three times, but “managed to get the data for the 3D model,” details of which have now been released. published in the journal Geosciences.
Andrey Umnikov, co-author of the study and director of the Russian Arctic Development Center, was the first to observe C17 which he made from a helicopter in July 2020. Depth of 98 metersmeter depth) the hole is located in the Yamal Peninsula in northwestern Siberia and is located next to three other explosion craters, including the Yamal crater, whose sudden appearance ADVISED the world to this strange phenomenon in 2014. The one that researchers are studying opened last summer in the middle heat record.
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The continuing theory behind these craters, of which 20 are known to exist, is that they are the result of permafrost melting. As Arctic is heated, the gas, especially methane, accumulates inside the cavities located at the top layer of permafrost. Eventually, the soil is no longer able to contain this pressure and gives a loud laugh in the form of a gas explosion, throwing material (ejecta) and forming a crater, according to this view. Explosion holes do not last very long, because they quickly fill with water and turn into lakes.
Hence the urgency of organizing an expedition to study C17 in detail and to do so as soon as possible after its discovery. The team, which included experts from the Skolkovo Institute of Science and Technology, visited the hole in Aug. 26, 2020 – about 40 days after it was first seen.
Upon arrival, the team noticed that the hole grew slightly in size, the result of the melting and collapse of the stone. The measurements showed that the depth of the hole was not uniform, varying between 29 and 33 meters deep.
“The new crater is impressive in its ideal state of preservation, first of all the cone-shaped tip from where the ejection was thrown, the outer parts of the mound that precipitated the crater, the crater walls themselves, which are incredibly well preserved and, of course , the gas cavity in the frozen bottom of the crater “ Evgeny Chuvilin, co-author of the study and a scientist at the Skoltech Center for Hydrocarbon Recovery, said.
Pieces of ejected material were observed up to 220 meters from the crater, emphasizing the power of the explosion.
Importantly, the team arrived on time to find the hole in an “almost clean state” and “without water filling it,” said study co-author Vasily Bogoyavlensky. At the same time, the frozen dome remained largely intact. Prior to the explosion, the cavity contained a circular dome with an elliptical bottom, Bogoyavlensky explained, adding: “From what we know we can say that the C17 crater is related to … deep damage [tectonics] and an abnormal flow of terrestrial heat. ”
Igor Bogoyavlensky flew the aerial drone, marking the first time a drone was used to supervise an explosive crater. It was also the first opportunity for scientists to study a relatively new crater that had not collapsed or filled with water. (Sscientists have climbed inside these things before, but only after most filling with water.) The drone, which sank to 15 meters, gathered valuable data, allowing the team to build a 3D model of the crater’s interior. Researchers have also documented features that are not visible from the surface, such as caves and a suspicious cavern at the bottom.
According to the 3D model, the crater has a diameter of about 25 meters, while the gas cavity at the bottom measures between 13 and 15 meters wide. The gigantic piece of dirty earth ice in the crater it measures 23 meters thick in some places. The total volume of the underground space is estimated at 353,000 cubic meters (9,910 cubic meters), including approximately 265,000 cubic meters (7,500 cubic meters) of ice.
The team also analyzed remote sensing data collected by helicopters and satellites, the latest of which showed that hole C17 formed at some point between May 15 and June 9 last year. Research published earlier this month used satellites to even discover more holes in the tundra.
Taken together, these observations reinforce the theory of how these holes are created: the constant accumulation of gas inside an underground cavity leads to huge pressures, leading to the formation of a “rising perennial mound” or PHM, according to the study. If the growth of a PHM reaches a critical threshold, a volcanic eruption occurs, forming a large crater.
“The specific shape of the underground cavity in massive ice, whose structure is described by a 3D digital model, is of great importance for the factual confirmation of the model of cavity formation,” the authors wrote in the paper. “It proves the pattern of its formation in the massive ground ice, the gas-dynamic mechanism of PHM formation and the strong explosion of gas with the destruction of the arcade portion of the underground cavity and PHM itself.”
Looking ahead, scientists hope to learn more about gas and where it comes from, how it accumulates in cavities and how such a powerful explosion can result. The team expects to review the C17 air vent later this year to continue the investigation of this curious natural phenomenon with a human-induced turn.