Inside Siberia's 'megaslump' – and why it is getting bigger

It has been called everything from the "gateway to the underworld" to a "tadpole-shaped gash" – and it's eating into the surrounding landscape "like a living thing".

The huge crater in Siberia is an "immense fracture" in the depths of the Russian Far East that "splintered open" just a few decades ago, said IFL Science. Now, "with climate change continuing to cook up this part of the world, the literal scar on the planet is continuing to grow".

The 'gateways to the underworld'

Officially known as the Batagay (also spelled Batagaika) crater or megaslump, the crater was first spotted on satellite images in 1991 after a section of hillside collapsed in northern Sakha in Russia.

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A megaslump is a vast expanding depression in the Earth's surface. These deep craters "appear like gateways to the underworld", said Treehugger. These "eerie sinkholes" are the result of melting permafrost – the frozen soil and rock that makes up the majority of the Arctic landscape. As our planet continues to warm, the permafrost thaws and the Earth "loosens and slumps".

The Siberian collapse revealed layers of permafrost, within the remaining portion of the hillside, that have been frozen for up to 650,000 years. In 2017, the megaslump was measured as up to 100 metres (328 feet) deep and around one kilometre (0.6 miles) long, but it has continued to grow.

A new study suggests its cliff face, or headwall, is retreating at a rate of 12 metres (40 feet) per year due to permafrost thaw. The collapsed section of the hillside, which fell to 55 metres (180 feet) below the headwall, is also "melting rapidly and sinking as a result", said Live Science. In other words, the megaslump is "slowly encroaching upon the landscape like a living thing", said Treehugger.

Locals in Siberia have mixed feelings about the unusual chasm, said Yahoo News. Many "fear" it "due to the strange ‘boom’ sounds it emits". But others have chosen to explore the site.

"We locals call it 'the cave-in'," local resident Erel Struchkov told Reuters last year, as he stood on the crater's rim. "It developed in the 1970s, first as a ravine. Then by thawing in the heat of sunny days, it started to expand."

All of this means that Siberia "boasts perhaps the largest thaw slump on the planet", said the BBC.

'Sign of danger'

The slump's expansion is "a sign of danger", Nikita Tananayev, lead researcher at the Melnikov Permafrost Institute in Yakutsk, told Reuters. The soil beneath the slump contains an "enormous quantity" of organic carbon that will release into the atmosphere as the permafrost thaws, further exacerbating the planet's warming.

That carbon is "mostly in the form of the frozen remains of plants and other organic material", along with "methane that has become trapped inside ice crystals", said the BBC.

With an "increasing air temperature" we can expect the crater to be "expanding at a higher rate," Tananayev said, and "this will lead to more and more climate warming in the following years".

But there is a positive too, Julian Murton, of the University of Sussex, told Yahoo News. Layers of soil going back 200,000 years have been exposed by the collapse – and the scientific community hopes that studying the crater may offer fresh insights into climate change.