Huge Crater Discovered in Russia — Cause Unknown

Scientists are rallying to figure out just what caused an enormous crater that has been discovered in Russia far from civilization in Siberia.  At 262-feet wide, this is quite an impressive indention on the Earth’s surface, and many are speculating as to why no one could have known about it until now.  As you might imagine, there are plenty of theories.  Some of the more tame ones are a meteor crash, an underground geyser exploding, or a natural gas explosion.

Scientists have been aggressively studying the crater, but as of yet, no one has offered up an agreed-upon hypothesis as to its cause.  What do you think?  What does this mean?