The slab by the wall has the same arrangement, a facing slab atop one, maybe two, sub-slabs.
I also do not know how to reconcile that photo with this one:
http://pixel-ca-dwr.photoshelter.com/galleries/C0000OxvlgXg3yfg/G00003YCcmDTx48Y/I00002lnQqBGT9AI/KG-oro-spillway-damage-10000-jpg
which has no sidewall collapse.
I’m just confused, I guess.