Following the earlier discovery of a giant hole in the ground in a region of Siberia so remote it's been dubbed "the end of the world," researchers say two more mysterious openings in the earth have been discovered.

Earlier this month a 250-foot-wide crater was discovered in the permafrost of the Yamal peninsula that baffled scientists, who were hard pressed to come up with an explanation for the phenomenon.

Now two more have been found; one of them, about 45 feet wide, displays earth apparently thrown from the hole, possibly by explosion or excavation, similar to that found around the earlier discovery, researchers say.

"Its diameter is about 15 meters. There is also ground outside, as if it was thrown as a result of an underground explosion," said regional parliament member Mikhail Lapsui, who was flown to the site by helicopter.

"According to local residents, the hole formed on 27 September 2013. Observers give several versions," he said. "According to the first, initially at the place was smoking, and then there was a bright flash. In the second version, a celestial body fell there."

At the bottom, 230 feet down, is an ice-covered lake, they say.

Reindeer herders came across a third crater east of Yamal, on the Taymyr Peninsula, almost falling into the hole situated on a traditional pasturing route.

They took photos of the opening, which they described as perfectly cone-shaped, and sent them to scientists in the region.

While its opening is only about 13 feet across, it is estimated to be as deep as 300 feet.

Scientists say the origin of all three of the crater-like sites is as yet unknown.

"It is not like this is the work of men, but [it] also doesn't look like natural formation," says one Russian expert.

All three of the strange holes will need further study, researchers say, to determine how they may have formed.

"Undoubtedly, we need to study all such formations," says Marina Leibman, Chief Scientist of the Earth Cryosphere Institute. "It is necessary to be able to predict their occurrence. Each new funnel provides additional information for scientists."

One leading theory for the origin of the enigmatic openings in the earth is the sudden explosion of a flammable cocktail of methane or shale gas underground, perhaps released from the permafrost by warming temperatures.

Scientists say they are examining previous satellite photos of the region in an attempt to determine when the holes may have formed.