"Scientists have revealed that Yellowstone Park has been on a regular eruption cycle of 600,000 years. The last eruption was 640,000 years ago…so the next is overdue. The next eruption could be 2,500 times the size of the 1980 Mount St. Helens eruption. Volcanologists have been tracking the movement of magma under the park and have calculated that in parts of Yellowstone the ground has risen over seventy centimeters this century." I am new to this forum so if you folks have already discussed "super volcanoes" then my apologies...

http://www.solcomhouse.com/yellowstone.htm

Absence of evidence is not evidence of absence.
Carl Sagan