By: Marisa M.
Photo from: Moscow State University
Most of us have seen or heard of craters on the Moon- those large circle-shaped indents on the surface- but how are they formed?
There are multiple types of craters that can be found on different planets, such as impact craters, volcanic craters, and explosion craters. Recently, there has been an increase in the amount of explosion craters on Earth, particularly Siberia. Explosion craters occur when certain materials or chemicals explode, causing a displacement of the ground around it. This explosion usually creates a circular hole, creating a crater. The recent sightings of craters during the past seven years have scientists questioning whether or not they are linked to the rising temperatures of the Earth.
There are a total of 17 craters in the Yamal Peninsula in Siberia as of 2020. The first crater was noted in 2013, and scientists still are not sure how these craters came to be. They do know that these craters were formed from pressure created within the Earth.
This process is called “cryovolcanism,” in which methane accumulates in the upper layers of permafrost. This buildup can cause enough pressure to break through the frozen ground (permafrost) and scatter soil and rock to create craters. This pressure has caused soil, rock, and ice to be thrown hundred of meters (around 300) into the air. Though cryovolcanism is used to describe the creation of explosion craters on Earth, cryovolcanism was originally defined to explain how explosion craters occurred on different planets.
This photo from Bychkov et al. Scientific Reports shows how the buildup in pressure caused gas to explode and cause thawed rock to emerge onto the surface of planets. In the case of Earth, though, these craters are filled with water, not thawed rock.
Earlier in 2020, there was a crater discovered by a Russian film crew who flew by the crater on accident. After reporting the sighting to local scientists and universities, it was concluded that the crater was at least 50 meters deep and 20 meters wide.
Most craters are formed in remote regions of the Arctic, making them hard to find and study since they turn into lakes after two years. One of the craters in 2014, though, was found to be only 30 kilometers (around 20 miles) away from the Bovanenkovskoye gas field, which could have explained the source from which methane gas was able to build up to the point of an explosion. This doesn’t explain the buildup of methane gas in other craters in more remote regions, though. Moscow State University was able to study satellite images of the crater in 2014, before and after it’s explosion. They were able to find out that there was an 80 meter-high mound in place of the crater before the explosion!
The image on the left is dated as June 9th, 2013, showing the mound before the explosion. The photo on the right is dated as June 15th, 2014 showing the crater created by the explosion of the mound.
Photo from Bychkov et al. Scientific Reports, 2018
The buildup of methane gas causes mounds to form that can explode within three to five years. Methane escapes the “cryopeg” layer, which is unfrozen ground that forms part of the permafrost layer, to form these mounds. The “cryopeg” layer is a unique characteristic to the Yamal Peninsula, which scientists conclude made it prone to all the explosion craters. Scientists also concluded that the mounds were able to explode in such a short amount of time because of Earth’s rising temperatures. The hot summers of 2012, 2016, as well as 2020 in the Yamal Peninsula support this conclusion. Before these irregularly high temperatures, these mounds usually collapsed in on themselves rather than exploded. The increasing temperatures cause the permafrost to melt and the pressure of the methane gas under the mounds to be released, causing the explosion craters. These explosions also release methane gas which can further increase temperatures and accelerate global warming (since methane is a greenhouse gas).
During the summer of 2020, Siberia recorded its highest temperature ever of 38 degrees celsius (100 degrees fahrenheit). This summer alone caused an extensive loss of permafrost which supports the theory that climate change has been creating these craters.
Scientists now are looking for ways to predict and find mounds before they burst into craters. Even though these craters mainly form in remote regions of Siberia, there are growing concerns for Siberia’s population safety. They can start exploding near gas plants or cities which can be dangerous. Once craters are filled with water and turned into lakes, there is no telling if it was a gas emission crater or not. That’s why time is of the essence in finding craters and seeing their explosive patterns. Scientists are still trying to figure out whether or not the ground's infrastructure is being harmed with each explosion. Much more research is expected with these cryovolcanism explosion craters.
Discussion Questions:
To what extent do you think climate change has an effect on explosion craters?
Where else do you think explosion craters can appear?
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