What conditions would exist on the ground beneath a high-yield nuclear blast for ~ the first 10-30 minutes?

I'm very interested in what you might call the "anatomy" of nuclear explosions, but there isn't much information on what conditions these explosions produce on the ground just beneath the detonation. I would imagine much of the ground immediately below would be vaporized, then a little further out some of the ground would be liquified, becoming increasingly solid the further away from the blast one went. But I'd -really- like to find some plausible numbers to go with those thoughts, if they're known.