The Yellowstone supervolcano first erupted 2.1M years ago, followed by one 1.6M years past, with the last occurring 640,000 years ago.
It doesn’t take a mathematical genius to calculate that another is likely sometime in the next few hunded thousand years. When it goes, it will wipe out much of the US.
http://en.wikipedia.org/wiki/Yellowstone_Caldera
http://en.wikipedia.org/wiki/Yellowstone_Hotspot
Nobody’s ever seen an alleged supervolcano. As far as scientists go, they aren’t able to verify their witchcraft, as they say in the industry, so I take wild theories with a grain of salt.