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Months after they started investigating a huge black hole in Siberia, Russian researchers say they have spotted still more suspicious-looking craters and lakes — and are calling for an urgent investigation of the phenomenon. Satellite imagery shows that one of the recently discovered craters, known as B2, is surrounded by more than 20 water-filled "baby craters," one researcher told The Siberian Times.

The Times quoted Vasily Bogyavlensky, deputy director of the Moscow-based Oil and Gas Research Institute, as saying that the craters are being mapped near Siberia's Bovanenkovo gas field. He linked their formation to gas emissions from beneath the surface, and possibly gas explosions. "Anyway, we must research this phenomenon urgently, to prevent possible disasters," he was quoted as saying.

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Experts have said the craters could be associated with climate change. Last year, Russian researchers reported heightened methane emissions at the crater sites and suggested that a long-term thaw was liberating underground reservoirs of natural gas. NASA scientist Tom Wagner told NBC News in December that the phenomenon might be caused instead by the collapse of tunnels and caves in the permafrost.

Wagner also predicted that more such craters would be found as researchers scanned through satellite imagery looking for fresh evidence.

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Dozens of new craters suspected in Arctic Russia along with the famous Yamal hole. http://t.co/JOfB26Qbh1 pic.twitter.com/haxPuNy0NI — Siberian Times (@siberian_times) February 23, 2015

Hey, @HouseScience, are you paying attention? Scary stuff> Scientists Sound Alert Over HUGE Siberian Mysterious Holes http://t.co/2E2n8wY58D — Syd's Soapbox (@heysyd) February 24, 2015

— Alan Boyle