What's the safest thing to do when in 2nd floor of a high-rise building during earthquake?

Answer 1

Exit the building?

You can hide under a heavy table or desk.
You can also stand in a doorway, since above you is a support beam.

Still, being on the second floor, you should be able to get to the stairs and get to the first floor and out of the buiding fairly quickly.

Answer 2

Pray HARD!