In addition to the risk of total collapse, there's also the risk that the remaining floors would be impassable. Debris (furniture, broken walls, etc) can be a

In addition to the risk of total collapse, there's also the risk that the remaining floors would be impassable. Debris (furniture, broken walls, etc) can be a dangerous obstacle, especially when you have to traverse several/dozens of flights of stairs, much of which will be wet, muddy/dirty, and possible destroyed in some places. This danger magnifies when you have to evacuate large amounts of people of varying mobility (young, old, sick, or otherwise infirm). Entrances and exits will be serious obstacles if not outright impassable, due to large amounts of debris and unknown/unstable physical integrity. Tsunami evacuation and safety policies are outlined for movement and monitoring large groups of people, not just individuals. With regards of where you should go -- go outside and move to higher ground.