Title says it all.
This should give a more concrete rating for Hanayama's AP.
Hanayama has a canonical height of 1.91m even while he was 15yo. This feat happened on his 14's so i think using the same height should be alright.
We have a, roughly, hemispherical shape for the crater. Using the formula, we get, then, a volume for 0.062 cubic meters or 62000cc.
I'll assume the wall to be made from concrete. I'll assume violent fragmentation.
20 * 62000 = 1240000J 1240Kj, 9-B