Over the years they have discovered that being under a doorway or table in an earthquake ended up with people getting crushed.
Tornados have wind, Earthquakes do not. On a building the highest point rocks the most and is more likely to fall.
I can remember one that was located in Mexico City that was about off the scale, it was felt all the way to Nevada! It was in the middle of the night, my birds started screaming, I jumped up and grabbed their cages and held on to ride it out. Felt like the building was going to come off the foundation.
There are also ones that have demolished ball parks, where people got under the seats and were killed by the falling upper levels.