Zombie apocalypse: Used by some preppers as a tongue-in-cheek metaphor for any natural or man-made disaster and "a clever way of drawing people’s attention to disaster preparedness". The premise of the Zombie Squad is that "if you are prepared for a scenario where the walking corpses of your family and neighbors are trying to eat you alive, you will be prepared for almost anything." Though "there are some... who are seriously preparing for a zombie attack".
With the world seeming to become a more volatile and dangerous place with every encroaching year, it can be hard to know exactly where you can feel safe. The modern media is overloaded with stories about violence, crime, and sensational pieces on the worst people in our society. But there have to be some places within the United States where the chances of anything like that happening to you is next to impossible, right?
For global catastrophic risks the costs of food storage become impractical for most of the population  and for some such catastrophes conventional agriculture would not function due to the loss of a large fraction of sunlight (e.g. during nuclear winter or a supervolcano). In such situations, alternative food is necessary, which is converting natural gas and wood fiber to human edible food.
Preparing for catastrophic or short range survival is extremely personal and most of us keep it tight to our chest. I think PowderKeg says it best – Invisible and then Nuttus who knows that not all of us are the same skill or wherewithal stage, yet as a TEAM we shore up each others weaknesses, learn off each others strengths and it is a continual building process going forward.
This type of prepper prides himself on how prepared he is for any apocalyptic event. He finds it hard to keep his mouth shut about his food preparation, water supply, and his self-sustaining environment that he built as a whole. The problem with this is if a disaster does happen, those ill-equipped groups will surely come for these religious preppers first.
To me, the best option is to store emergency food. How much? If you have none, store enough for a few days. If you have enough for a few days, get enough for a week. How much you store depends on what time frame you think you're at risk for having to be completely independent. The early settlers of the southwest liked to store enough food for a whole year and still do to this day!