FWIW, and important on a much smaller scale, we lost all of Helen Keller's archives/memorabilia in a basement museum of one of the Twin Towers. Not sure what else was lost, but that sticks with me for some reason. :(
And lets not kid ourselves. We couldn't even handle Katrina/Rita because of the magnatude of the destruction (not getting into the blame game for now.)
It truly WILL be every Man for Himself if we get nuked. So, don't be scared; be prepared as best you can be with food, a basement (yours or a neighbors), cots, wind-up radio, bottled water, meds if you need them, something to make fire, etc. We have a great kit put together for tornadoes & blizzards in our basement. A lot of that "survival" stuff would come in hand in this instance, too.
Unless you're at Ground Zero...but who can say where that will be against these nutjobs?
We have been "tent campers" for over thirty years. (Archaeological "digs" are seldom in civilized and easily-accessible locations...) So, when the need arises, we just shift into "camping mode".
I recall one hurricane in MA: when the electricity went off, my wife just lifted her pot of chowder-in-progress off the electric range and onto the Coleman stove. While others were panicking and depressed, we just enjoyed a comfortable "indoors campout". In this (nuke) scenario, we would have done the same -- but in the basement...