“The water pipe break was the collapse, the very beginning of it.”
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Yes, at or near the very beginning of the collapse.
A leaking water pipe (or a drainage pipe) over years can cause a sinkhole to happen in limestone. I have no idea if limestone is shallow or even present at the site.
I doubt that the sudden rush of water from the pipe was the cause of the collapse - it was just early evidence (by a few minutes) that something had gone wrong.
I will always be looking around when I enter a hi rise underground parking garage.
I worked on the 10th floor of a 20 story building for awhile once. I never liked it. I used to study out the windows and figure out which tree I could make for by flinging myself out the window in the event of a disaster.
Remember seeing those flashing lights as the building fell?
Maybe that was the fire alarm. Pipe snaps and set off the bells and strobes.