New here...but years ago when I was but a weee lad, I worked at Wally-World as a Sporting Goods Dept. Manager. We had a bad ice storm and trucks were down for a few days. Power was out in 10% or so of the homes and I saw first hand the dependence of our society on stores. Camp fuels, food, batteries, candles, bottled water, and many other items were gone. The trucks were only down for a few days and the shelves were emptied on the first morning. Not just in our store, but community wide. Just a small example of a situation that is much less severe than the one posed on this thread. Just my two cents.
I've seen shelves in the store cleaned out in short order. I've been in line waiting for rationed gas. I was in the hospital recovering from being blown up when it was surrounded by angry gangs 'demanding justice' for Rodney King.
I think that some movies have really done a good job of describing what the "worst of the worst" that can happen. Combine what was put onto big screen (post apocalyptic style movies) with the reality of what happened in the US southern states during hurricane season, in California during an earthquake, in British Columbia during the last fire-storm, in Africa during their drought, in the Asian countries during that last Tsunami and you will see what people will be willing to do to survive - ANYTHING!!!