Sue captures my answer and my region of the country. The one quibble I have is based on recent knowledge, and not so much direct experience yet - sanitation after a flood or earthquake. Talking to folks who know, certain parts of the Seattle area (specifically the Eastside) could experience sewage interruptions and backups from remote but related flooding. And the same could occur after an earthquake. The idea of staying in the house or camping in the backyard while sewage backs up through all household orifices isn't terribly appealing. Cleanup is a priority (though I still need to answer, where can cleaned up sewage go if the sewer doesn't work), but keeping my family safe and healthy is bigger still. I would tend to evacuate family members in such a situation, and proceed with a safe clean up if I could. If not, get out of dodge myself.

Bottom line, Sue nails it - know when to get out. Make a decision, have a plan, don't look back.