Buildings of the size have to be anchored to bedrock.
I wonder what that means. Even if a building is "anchored to bedrock", if the bedrock is some distance below, perhaps the anchors/pilings are not always sufficient to support the entire weight of the building, especially if some of the intervening fill is displaced.
“perhaps the anchors/pilings are not always sufficient to support the entire weight of the building”
Then that would be a failure of the engineers. I’m no engineer or architect, but it’s just plain common sense that you anchor these kinds of buildings to bedrock with sufficient structural support so that the weight of the building is transferred to the bedrock and not the intervening material. Anything less is courting disaster.
You pond the pilings down until you hit bed rock.