Hopefully, the increased volcano activity over the past few years will not set off Yellowstones super volcano. Unfortunately, it erupts with near-clockwork precision every 600,000 years. The last eruption was more than 640,000 years ago – we are overdue for annihilation.Super volcanoes do not form mountains. They actually create depressions in the ground called calderas. In super volcanoes the magma is so viscous that volcanic gasses that normally trigger an eruption cannot pass, so a massive amount of pressure begins to build up. This continues for hundreds of thousands of years until an eruption occurs, which blasts away a huge amount of ground, forming a new caldera.Scientists searching for the caldera in Yellowstone park could not see it because it was so huge – only when satellite images were taken did the scale of the caldera become apparent, 53 miles by 28 miles. See the map to the left.

via The Sun Is Freaking Out.