What are you actually supposed to do in an earthquake?

Even if you leave the building it has a change of collapsing still.

..and your point?

I think that means you can't keep a building from collapsing by staying inside.

Earthquakes have after shocks most of the time. Which could be more powerful then the initial quake

That structure could come down instantly or even hours later.

However many buildings avoid this because they are fused to the bed-rock,
rather then being on top of soil. Later buildings are earthquake proof. Leaning Tower of Pisa is leaning because the bedrock is below where it was built and the land was soft in that specific position.