During an earthquake - hiding from broken glass shards flying out from buckling windows is real. Your desk is your best defense - a weak one perhaps, but better than nothing.
When I was teaching school in a shi**y trailer that was good enough for poor people, the ceiling tiles kept falling out and the rods that held them in place would swing down.
I complained for months and the sh** manager of that department told me new BS every time. Someone would come in and pretend to fix it but it kept happening.
Eventually, one of the rods swung down and hit a kid in the eye.
We got him up to the office and the district paid on the spot for the ER treatment (no permanent damage) but the discussion in the classroom after was excellent.
One of these fifth graders said that he had seen the ceiling tile start to buckle and felt bad that he didn't yell out . . . So we set up the word "Alert" and practiced - with that eagle eyed kid, or me, calling out "ALERT" and the kids would all get under their desks.
We practiced with a timer to see how fast we could get.
The principal came down while we were working on the project and was appalled regarding this use of instructional time and I told her off right there in front of the class.
Hiding under your desk won't save you from a nuke or a bullet, but it has its uses.