I hear yah. St. Helen's is a firecracker compared to a nuke! The last eruption of the caldera was the Lava Creek Tuff 640,000 years ago and ejected 1,000 cubic kilometers. The little ones, such as 13,000 years ago left a 5k diameter crater near Mary Bay. And those happen every 20,000 years or so. The yellowstone caldera eruption 2.1 million years ago poured out an estimated 2,450 cubic kilometers of ash, both covered most of north america from the mississippi west. That makes it at least 8,000 (according to the NGS) times more powerful then St. Helen's in term of ash. Right now, there is a 3,600 cubic mile caldera under Yellowstone
Over a 1,500 square mile 'crater top'. Volcanic debris from St. Helens covered and area about 30k in diameter, this bad boy could do one nearly 1,000 miles in diameter.
http://exodus2006.com/supervol.html some good maps
This of course would solve the debate about the fence on the mexican border... it would be us running across the border!
