Satellites show giant hole ringed by 20 'baby craters'.
B1 - famous Yamal hole in 30 kilometres from Bovanenkovo, spotted in 2014 by helicopter pilots. Pictures: Marya Zulinova, Yamal regional government's press service
Respected Moscow scientist Professor Vasily Bogoyavlensky has called for 'urgent' investigation of the new phenomenon amid safety fears.
Until now, only three large craters were known about in northern Russia with several scientific sources speculating last year that heating from above the surface due to unusually warm climatic conditions, and from below, due to geological fault lines, led to a huge release of gas hydrates, so causing the formation of these craters in Arctic regions.
Two of the newly-discovered large craters - also known as funnels to scientists - have turned into lakes, revealed Professor Bogoyavlensky, deputy director of the Moscow-based Oil and Gas Research Institute, part of the Russian Academy of Sciences.
Examination using satellite images has helped Russian experts understand that the craters are more widespread than was first realised, with one large hole surrounded by as many as 20 mini-craters, The Siberian Times can reveal.
Four arctic craters: B1 - famous Yamal hole in 30 kilometres from Bovanenkovo, B2 - recently detected crater in 10 kilometres to the south from Bovanenkovo, B3 - crater located in 90 kilometres from Antipayuta village, B4 - crater located near Nosok village, on the north of Krasnoyarsk region, near Taimyr Peninsula. Picture: Vasily Bogoyavlensky
'We know now of seven craters in the Arctic area,' he said. 'Five are directly on the Yamal peninsula, one in Yamal Autonomous district, and one is on the north of the Krasnoyarsk region, near the Taimyr peninsula.
'We have exact locations for only four of them. The other three were spotted by reindeer herders. But I am sure that there are more craters on Yamal, we just need to search for them.
'I would compare this with mushrooms: when you find one mushroom, be sure there are few more around. I suppose there could be 20 to 30 craters more.'
He is anxious to investigate the craters further because of serious concerns for safety in these regions.
The study of satellite images showed that near the famous hole, located in 30 kilometres from Bovanenkovo are two potentially dangerous objects, where the gas emission can occur at any moment.
Satellite image of the site before the forming of the Yamal hole (B1). K1 and the red outline show the hillock (pingo) formed before the gas emission. Yellow outlines show the potentially dangerous objects. Picture: Vasily Bogoyavlensky
He warned: 'These objects need to be studied, but it is rather dangerous for the researchers. We know that there can occur a series of gas emissions over an extended period of time, but we do not know exactly when they might happen.
'For example, you all remember the magnificent shots of the Yamal crater in winter, made during the latest expedition in Novomber 2014. But do you know that Vladimir Pushkarev, director of the Russian Centre of Arctic Exploration, was the first man in the world who went down the crater of gas emission?
'More than this, it was very risky, because no one could guarantee there would not be new emissions.'
Professor Bogoyavlensky told The Siberian Times: 'One of the most interesting objects here is the crater that we mark as B2, located 10 kilometres to the south of Bovanenkovo. On the satellite image you can see that it is one big lake surrounded by more than 20 small craters filled with water.
'Studying the satellite images we found out that initially there were no craters nor a lake. Some craters appeared, then more. Then, I suppose that the craters filled with water and turned to several lakes, then merged into one large lake, 50 by 100 metres in diameter.
'This big lake is surrounded by the network of more than 20 'baby' craters now filled with water and I suppose that new ones could appear last summer or even now. We now counting them and making a catalogue. Some of them are very small, no more than 2 metres in diameter.'
Satellite images showing pingo before the gas emission on the object B2 (top). Lake formed here at the place of the number of craters and the network of more than 20 'baby' craters around (bottom). Picture: Vasily Bogoyavlensky
'We have not been at the spot yet,' he said. 'Probably some local reindeer herders were there, but so far no scientists.'
He explained: 'After studying this object I am pretty sure that there was a series of gas emissions over an extended period of time. Sadly, we do not know, when exactly these emissions occur, i.e. mostly in summer, or in winter too. We see only the results of this emissions.'
The object B2 is now attracting special attention from the researchers as they seek to understand and explain the phenomenon. This is only 10km from Bovanenkovo, a major gas field, developed by Gazprom, in the Yamalo-Nenets Autonomous Okrug. Yet older satellite images do not show the existence of a lake, nor any craters, in this location.
Not only the new craters constantly forming on Yamal show that the process of gas emission is ongoing actively.
Professor Bogoyavlensky shows the picture of one of the Yamal lakes, taken by him from the helicopter and points on the whitish haze on its surface.
Yamal lake with traces of gas emissions. Picture: Vasily Bogoyavlensky
He commented: 'This haze that you see on the surface shows that gas seeps that go from the bottom of the lake to the surface. We call this process 'degassing'.
'We do not know, if there was a crater previously and then turned to lake, or the lake formed during some other process. More important is that the gases from within are actively seeping through this lake.
'Degassing was revealed on the territory of Yamal Autonomous District about 45 years ago, but now we think that it can give us some clues about the formation of the craters and gas emissions. Anyway, we must research this phenomenon urgently, to prevent possible disasters.'
Professor Bogoyavlensky stressed: 'For now, we can speak only about the results of our work in the laboratory, using the images from space.
'No one knows what is happening in these craters at the moment. We plan a new expedition. Also we want to put not less than four seismic stations in Yamal district, so they can fix small earthquakes, that occur when the crater appears.
'In two cases locals told us that they felt earth tremors. The nearest seismic station was yet too far to register these tremors.
Crater B3 located in 90 kilometres from Antipayuta village, Yamal district (top). Crater B4 located near Nosok village, on the north of Krasnoyarsk region, near Taimyr Peninsula. Pictures: Local residents
'I think that at the moment we know enough about the crater B1. There were several expeditions, we took probes and made measurements. I believe that we need to visit the other craters, namely B2, B3 and B4, and then visit the rest three craters, when we will know their exact location. It will give us more information and will bring us closer to understanding the phenomenon.'
He urged: 'It is important not to scare people, but to understand that it is a very serious problem and we must research this.'
In an article for Drilling and Oil magazine, Professor Bogoyavlensky said the parapet of these craters suggests an underground explosion.
'The absence of charred rock and traces of significant erosion due to possible water leaks speaks in favour of mighty eruption (pneumatic exhaust) of gas from a shallow underground reservoir, which left no traces on soil which contained a high percentage of ice,' he wrote.
'In other words, it was a gas-explosive mechanism that worked there. A concentration of 5-to-16% of methane is explosive. The most explosive concentration is 9.5%.'
'The parapet of these craters suggests an underground explosion.' Pictures of Yamal crater taken by Vasily Bogoyavlensky
Gas probably concentrated underground in a cavity 'which formed due to the gradual melting of buried ice'. Then 'gas was replacing ice and water'.
'Years of experience has shown that gas emissions can cause serious damage to drilling rigs, oil and gas fields and offshore pipelines,' he said. 'Yamal craters are inherently similar to pockmarks.
'We cannot rule out new gas emissions in the Arctic and in some cases they can ignite.'
This was possible in the case of the crater found at Antipayuta, on the Yamal peninsula.
'The Antipayuta residents told how they saw some flash. Probably the gas ignited when appeared the crater B4, near Taimyr peninsula. This shows us, that such explosion could be rather dangerous and destructive.
'We need to answer now the basic questions: what areas and under what conditions are the most dangerous? These questions are important for safe operation of the northern cities and infrastructure of oil and gas complexes.'
The latest expedition to Yamal crater was initiated by the Russian Centre of Arctic Exploration in early November 2014. The researchers were first in the world who went down the crater of gas emission. Pictures: Vladimir Pushkarev/Russian Centre of Arctic Exploration
Pingos are mounds with an ice core found in Arctic and sub-Arctic regions.
They can reach up to 70 metres (230 ft) in height and up to 600 m (2,000 ft) in diameter. They usually appear when groundwaters penetrate between permafrost and the top layer, which melts in summer season. They usually form in drained lakes or river channels.
However, gas is not a factor in their creation.
See previous stories on the craters:
Locals hear 'booms from the underworld' in giant ravine but now scientists say it holds secrets of the planet's past.
Remains of suspected female of Turkik origin found in at an altitude of 2,803 metres in the Altai Mountains.