A while back some people here (the names temporarily elude me) did some tower R&D with inverse crater displacement. I starting plinking around with the idea. It bore interesting results.
What is a slight negative to this method as opposed to using simple shapes and extruding those, is that the crater shader footprint on the terrain is not represented in OGL, which makes ID and other needs a bit of a pain when making adjustments. And, of course, you're limited to a circular profile.
BUT, the rim and skirt values come in real handy for blending with the ground below (not visible here for the clouds) so it of course depends on the needs of the shot or sequence you're doing.
Overall, though, it's a pretty speedy way to achieve the goal.