Scientists say large Siberian craters formed by methane eruptions
21 July 2015
According to an article in the Siberian Times, large craters up to 100 metres across and 60 metres deep recently discovered on the Yamal Peninsula in Siberia are caused by gas eruptions triggered by melting permafrost. The article gives details of findings from the latest research by teams of Russian scientists sent to investigate the craters after they were first spotted in 2014.
Picture: Yamalo-Nenets Autonomous regional government
Professor Vasily Bogoyavlensky, who led the latest expedition, recently examined the most famous crater - known as B-1 - which is 25 km from the Bovanenkovo gas field.
The professor, deputy director of the Moscow-based Oil and Gas Research Institute, part of the Russian Academy of Sciences, said the craters were created from pingos, mounds with an inner ice core common in Arctic and sub-Arctic regions, that melted and were filled with gas from below.
The gas then erupted, forming the crater, although Bogoyavlensky said readings taken by the latest expedition showed no abnormal gas levels at the site. The craters are rapidly filling with water and creating small lakes.
He said that normally the pingos would thaw and collapse but gas eruptions were a phenomenon never observed before, linked to the warming weather conditions seen in recent years.
Craters B-3 and B-4, discovered in 2014 and 2015 respectively, are formed the same way, he believes.
But another giant crater B-2, which is located 20 km north of B-1 and is now a lake 50 by 100 metres in size, differs from them significantly, according to the professor. This crater has small 'satellite' holes around the main one.
“The presence of the small craters around the big one - we can see more than 30 of them - can also indicate that the mouth of this crater had side channels, so the structure of this object can be compared to a tree. Gases went through the channels, forming many small craters, but not a big one.
“The other option is that here the gas went not from the depth via the cracks in the ground, but it was gas hydrate located close to the surface,” he said.
The Siberian Times quoted Bogoyavlensky as saying that given the proximity of the craters to oil and gas extraction sites, careful observation and research was required. But he said at the present time there was no reason to panic.
Some pingos on the Tuktoyuktuk Peninsula in northern Canada are two km in diameter and up to one hundred metres in height, but most in Siberia are one to two hundred metres in diameter and about ten to twenty metres in height.
Bogoyavlensky said there had been a recent case of a big pingo near a gas pipeline, which began to lift the pipe.
“The officials have not yet taken any measures to move the pipe, but we will continue to research and inform on possible dangers to infrastructure,” he said.