I'm not familiar with the site. From what I've read, I picture a sidewalk near a science building, on the periphery of the campus. May or may not have been a road nearby. I haven't seen any pictures of the site, and I haven't heard anything other than conjecture that there wasn't a crater. Also, a report has said that windows were damaged. That could have been a result of the blast, or shrapnel. This thing is like a mentat exercise. Very little information--so no conclusions are possible--unless you live on Dune and you are really, really sharp.
I don't know the exact spot, because it was still taped off when we left Norman this afternoon, but here is a satellite photo of the area. Of course, you can see the stadium. I'm not sure how to describe the spot of the explosion to you on the photo, but if you look at the stadium, go to the left (west) stands, where they extend further out; follow in a straight line to the left to the first building with a very white roof (before the tree-lined mall area.); this is almost a t-shape with two different buildings, and I believe the bomb went off in the area north of that, in the shadow of that building on this photo.
It is paved (sidewalks.) Most explosions will (generally) follow the path of least resistance; in other words, they will not make a crater. Artillery shells have significant downward force from their trajectory that causes them to penetrate the ground. Even the Murrah building bomd, whose force destroyed a building, did not crater the street, so far as I know.