I presume they are, but i noticed them first time on 3rd or 4th level, where some hallways are collapsed and I'm just thinking that it would be cool if hallways are collapsed because of the earthquakes and that you could outrun them. And I don't know if earthquakes are time or location triggered.
So for example if earthquakes are time triggered, and you get to the (should be) collapsed hallway and it is not collapsed then you don't have to go all the way around.
Edit: Anybody been there, done that before the first earthquake?