In areas prone to earthqaukes and wildfires, consider building a fire and qauke resistant storage shed/gargage on your land.
If your house is uninhabitable, it might be possible to live short term in this structure, especialy if it could be extended by tents or awnings.
Re-inforced concrete construction should withstand all but the very worst events.
A number of firms offer to build concrete tornado shelters, such would also appear to be fire and qauke resistant and might be worth considering even in areas with little tornado risk.

If flooding is the main risk, consider not only a two storey house, but remember to keep important supplies and equipment upstairs.