The real problem is that it seems a small collapse of the open area next to the pool over a parking level propagated to a large portion of the structure in seco

The real problem is that it seems a small collapse of the open area next to the pool over a parking level propagated to a large portion of the structure in seconds. I suspect slabs coming off pillars took away horizontal support from pillars on the "good" side of the slab. Then those pillars came away from adjacent slabs. There's a number of warehouse rack collapses where a single failure takes down all of them. I suspect a similar mechanism.