Louis,

If you do a google search on yellowstone super volcano, you'll find tons of
information on it.  I believe there are something like 6 super volcanos
worldwide.  They are generally underground, that is, their top is at ground
level.  The one in yellowstone is literally 60 miles wide.  Places in
yellowstone are currently off limits to visiters because the ground is 200
degrees and melts shoes if walked upon.  I would guess if it blows, there
won't be much ham radio communications, except for maybe real good e
scatter, for some time to come.  If it blows, they are talking about perhaps
25 feet of ash even in Denver.  Boy, what a noise that thing will make, haw.
I've decided, if it blows, I'm going out in my front yard to experience the
full effects of everything.  There won't be much reason to stay indoors,
that's for sure.  Not this close to ground zero.

Phil.
K0NX