Great question.

In a 'disaster', there is a breakdown of the standard expectations -- an fancy way of saying something gets broken. Loss of power, water, transportaion, heat, etc. Just what and for how long, depends on the nature of the event.

Your planning should start with : What is likely to happen here? To me?

Each area has a few likely events; San Fran has earthquakes, power outages. Maimi has heat, hurricanes, gangs. Winnipeg has cold and blizzards.
Wichita has heat & cold issues, blizzards and tornadoes, but civil unrest is very rare.

Figure out what could or has happened in your climate, then plan for that.

More later