[GOPJ]

One of their first tasks, Doss told me, was to draw up an "earthquake and volcano hazards plan"-a plan of action in the event of a crisis. "There isn't one already?" I said. "No. Afraid not. But there will be soon."

I assume that's for a small eruption - a large one would require 5 or 6 states to be evacuated...

[2ndDivisionVet]

As I understand it, a large eruption would probably be a world-killer.

Yellowstone Caldera Resources

http://www.freerepublic.com/focus/f-bloggers/2157979/posts