There are many sources of pre-prepared foods with some of them lasting up to 10 years available. Google emergency supplies. Otherwise, most people who are trying to be prepared for natural disasters buy extra of whatever they like that is on sale. The ultra prepared usually go for the freeze dried. I would say, whatever your level of preparation keep water and food for your family and pets for a minimum of three weeks. If the event was serious enough, it might take the government that long to start bringing supplies into a region if infra structure is completely destroyed it could be longer. I know this seems silly to some people, but watching people plucked from roof tops after Hurricane Katrina should have been a lesson for everyone to learn from.