Ten years ago, mysterious craters appeared in Siberia, covered with permafrost. They were created as a result of gigantic explosions. Scientists have long wondered why such craters occur only in this region. Finally, British and Spanish researchers managed to solve the mystery.
Mysterious craters, 50 meters deep and up to 70 meters in diameter, first appeared on the Yamal and Gydan peninsulas in Russia in 2014. As the Live Science portal writes, pieces of rock and ice scattered across the landscape around the craters indicated that they were created as a result of gigantic explosions. Such geological formations have never been found anywhere else in the Arctic. Now new research may finally explain why these explosions only occur in Siberia.
“There are very specific conditions in Siberia that allow such craters to form,” wrote study author Ana Morgado from the University of Cambridge in the UK in a statement. “It may be a very rare event, but the amount of methane released during it could have quite a large impact on global warming,” she added.
Mysterious craters
Over the past decade, scientists have considered several factors that may have contributed to the formation of mysterious craters in Siberia. They linked the genesis of their formation to the thawing of permafrost and the disintegration of water and methane crystals, called methane hydrates, into methane and water.
– We knew that something was causing the methane hydrate layer to disintegrate – Morgado explained in an interview with Live Science.
To find out how all these factors are related, scientists from the University of Cambridge and Spain's Universidad de Granada developed a series of equations and conducted experiments in the laboratory that mimicked permafrost. They determined that the explosions were likely caused by high pressure, which explodes like a balloon when overinflated. They then had to find out what caused this high blood pressure.
Research published on September 26 in the journal Geophysical Research Letters shows that cryopegs, i.e. pockets, lenses of very cold brines, will explode. They are located directly above the methane hydrate. Cryopegs have been found only in northern Russia. They are the remnants of prehistoric seas that disappeared during the last ice age. Cryopegs remain liquid despite their icy surroundings due to their high pressure and salt content.
Because cryopegs are much saltier than the surrounding permafrost, water from the melting permafrost flows into their pockets to equalize the salt concentration between the two bodies of water. This slowly builds pressure inside the cryopegs. Eventually, the stress becomes so great that cracks form in the permafrost above the cryopegs. This releases pressure in the permafrost.
The methane hydrates directly beneath the cryopegs are stable due to low temperatures and high pressure, so a sudden drop in pressure in these layers could cause the methane to separate from the crystals and return to a gaseous state, triggering a huge explosion. The study authors noted that these processes likely occur over several decades, which is why explosions are rare.
Main photo source: aalutcenko/AdobeStock