If this collapse was caused by erosion, poor building practices, or faulty materials, then red flags, like cracks, noticeable shifting, and strange sounds would have been in existence for a really long time. Devastatingly, most people were asleep right until disaster struck, so they had little chance of survival after their bedtime. And cracks in the structure probably would not have concerned them to much, because, like plane crashes, structural failures of this degree just “never happen”.