Prepare by problem

Real emergencies do not respect categories. A winter storm is a power problem, a heating problem, a water problem if your pipes freeze, and a communications problem when the cell sites run their batteries down. Reading about it one subject at a time misses the way the failures chain together.

These hubs are organised the other way round: by the event, pulling in whichever guides are relevant regardless of which pillar they live in. Each one opens with what actually tends to happen, then groups the guides in the order you would need them.