Yeah, I noticed a lot of attention in the media is on the pool support corrosion, but it apparently did not collapse, though it seems to have emptied out. With

Yeah, I noticed a lot of attention in the media is on the pool support corrosion, but it apparently did not collapse, though it seems to have emptied out. With the other anecdotal notes about the subfloor pumps wearing out and water pooling in the subfloor garage closer to the building, it seems more likely there was a longstanding leak that lead to a sinkhole forming or perhaps rebar corrosion. I recall from my civil engineering course that concrete has a high compression yield point but a poor tensile one, hence the need for rebar. Take away part of the foundation or wear away the structure in such a way that the weakened rebar is forced to take the load, and suddenly you have a catastrophic failure like the one that occurred.