Siberia’s newest explosive crater has been mapped in 3D

For the very first time, geologists have used an aerial drone to map the interior of a giant crater, the tastes of which have appeared with increasing regularity in Siberia.. The resulting 3D model, along with other data collected during the investigation, strengthens the dominant theory connecting those bizarre holes in the tundra to increase the heat.

“Over the years we have gained a lot of experience with surveillance drones, but this underground aerial survey of the C17 crater was the most difficult task I have ever had to face, having to lay down on the edge of a 10-story deep crater and swing my arms to control the drone, ”said Igor Bogoyavlensky, a geologist at the Oil and Gas Research Institute of the Russian Academy of Sciences, in a statement. declaration.

Bogoyavlensky said he almost lost the drone three times, but “managed to get the data for the 3D model”, details of which have now been published in the journal Geosciences.

Andrey Umnikov, study co-author and director of the Russian Arctic Development Center, was the first to spot C17 which he did from a helicopter in July 2020. The 98 feet deep (30-meter deep) is located in the Yamal Peninsula, northwest of Siberia, and it is located near three other erupting craters, including the Yamal crater, the sudden appearance of which alert world to this strange phenomenon in 2014. The one that researchers are studying opened last summer in the middle of heat record.

The current theory behind these craters, 20 of which are known to exist, is that they are the result of melting permafrost. Like the Aas the arctic warms, gas, mainly methane, accumulates inside cavities in the top layer of permafrost. Eventually, the ground is no longer able to hold this pressure, and it gives out a powerful burp in the form of a gas explosion, throwing material (ejecta) and forming a crater, according to this view. Eruption holes do not last very long as they quickly fill with water and turn into lakes.

Hence the urgency to organize an expedition to study the C17 in detail, and to do so as quickly as possible after its discovery. The team, which included experts from the Skolkovo Institute of Science and Technology, visited the hole on August. February 26, 2020 – approximately 40 days after it was first detected.

Upon arrival, the team noticed that the size of the hole had increased slightly as a result of the rock melting and collapsing. Measurements showed that the depth of the hole was not uniform, ranging from 95 to 108 feet (29 to 33 meters) deep.

“The new crater is impressive in its ideal state of preservation, mainly the cone-shaped top from which the ejecta were thrown, the outer parts of the mound that precipitated the crater, the walls of the crater itself which are incredibly well preserved, and, of course, the gas cavity in the icy bottom of the crater, “ Evgeny Chuvilin, study co-author and scientist at the Skoltech Center for Hydrocarbon Recovery, said.

Pieces of ejected material were spotted up to 220 meters (720 feet) from the crater, underlining the force of the explosion.

Importantly, the team arrived in time to find the hole in an “almost pristine condition” and without “any water filling it,” said study co-author Vasily Bogoyavlensky. At the same time, the ice dome has remained largely intact. Before the explosion, the cavity contained a circular dome with an elliptical bottom, explained Bogoyavlensky, to which he added: “From what we know, we can say that the C17 crater is related to … a deep fault. [tectonics] and abnormal earth heat flux. ”

Igor Bogoyavlensky flew the aerial drone, marking the first time that a drone has been used to monitor an eruption 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 of the time fill up with water.) The drone, which reached a depth of 15 meters, collected valuable data, allowing the team to build a 3D model of the crater’s interior. Researchers also documented features not visible from the surface, such as caves and a suspected cave at the bottom.

According to the 3D model, the crater is about 82 feet (25 meters) in diameter, while the gas cavity at the bottom is 43 to 49 feet (13 to 15 meters) wide. The gigantic piece of dirty land ice in the crater is 75 feet thick (23 meters) in some places. The total volume of underground space is estimated at 353,000 cubic feet (9,910 cubic meters), including approximately 265,000 cubic feet (7,500 cubic meters) of ice.

The team also looked at remote sensing data collected by helicopter and satellites, the latter showing that hole C17 formed at some point between May 15 and June 9 last year. Search published earlier this month used satellites to discover even more holes in the tundra as well.

Taken together, these observations strengthen the theory on how these holes are created: The regular build-up of gas inside an underground cavity leads to enormous pressures, leading to the formation of a “perennial uplift mound”, or PHM, according to study. If the growth of a PHM reaches a critical threshold, a volcanic-type explosion ensues, forming a large crater.

“The specific shape of the underground cavity in massive ice, the structure of which is represented by a 3D digital model, is of great importance for the factual confirmation of the pattern of the formation of the cavity,” wrote the authors in article. “This proves the pattern of its formation in massive ground ice, the gas-dynamic mechanism of PHM formation and the powerful gas eruption with the destruction of the arch part of the underground cavity and the PHM itself.“

Looking ahead, scientists hope to learn more about the gas and where it comes from, how it accumulates in cavities, and how it can lead to such a powerful explosion. The team plans to revisit the C17 vent later this year to continue their investigation of this curious natural phenomenon with human-induced torsion.