C. Northcote Parkinson

By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning.

The best way to get a sense of what kinds of emergencies might present themselves in your community is by contacting local chapters of the American Red Cross or offices of emergency management in the region or state. Most large cities will have their own offices of emergency management.