Decoding the mystery of the giant 'death hole' in Siberia

New research suggests that the region's geological conditions and the effects of climate change have led to the appearance of a series of giant "death holes" in Siberia over the past 10 years.

In 2014, a giant crater appeared on Siberia's Yamal Peninsula. The sudden appearance of this "death hole" and the surrounding material suggested that an explosion had occurred.

Scientists and locals later discovered more than a dozen similar giant "death holes" in the area, some as deep as 50m.

Scientists survey a giant crater that appeared on the Yamal Peninsula, Siberia in August 2020 - (Photo: Evgeny Chuvilin).

During the investigation, scientists discovered unusually high concentrations of methane gas around the craters, leading them to believe that a large release of methane gas created the craters.

However, new research, by chemical engineer Ana Morgado (working at the University of Cambridge) and colleagues, suggests that the theory of melting permafrost is not enough to explain the formation of the holes.

Instead, they believe a unique set of conditions related to the area's unusual geology and the effects of climate change set in motion a process that led to the release of methane gas through explosions.

According to the study , the warming of the surface soil led to rapid pressure changes deep underground, which eventually led to the release of extremely strong methane gas. The authors determined that the methane release process originated from a physical reaction.

For the analogy, the team thought of a pump and a bicycle tire. If you overinflate the tire, it will burst. In the Siberian case, the pump is osmosis —the movement of liquids to equalize the concentrations of the substances dissolved in them.

According to IFLScience on October 1, the Yamal Peninsula has a layer of permafrost clay that acts as a barrier against permeation. Inside this layer of soil in some places on the Yamal Peninsula is a layer of unfrozen water with high salinity called cryopeg. Below the cryopeg are layers of water - crystalline methane (methane hydrate or fire ice) that are maintained stable due to low temperatures and high pressures.

However, climate change has allowed water from the ice to seep down, causing a change in pressure and cracks to appear. These cracks spread, causing a sudden drop in pressure deep underground, rupturing the methane hydrate structure below the cryopeg and releasing methane gas through an explosion.

The team concluded that the process that led to the methane explosions took decades to occur, consistent with the warming climate since the 1980s.

The research is published in the journal Geophysical Research Letters .