FEMA descended from Civil Defense. Civil Defense was prepared to shelter survivors of nuclear attack. FEMA took on other roles such as hurricane relief when it was apparently decided there would be no defense against nuclear attack.
FEMA may have reports and plans by the truckload, but they have little organization and funding. In case of nuclear attack, FEMA will take over organization of relief, but most of their workers will be new hires and temporaries, as well as volunteers. No one will have the slightest idea what to do about anything. You will be on your own.
How about floods, earthquakes, and huricanes?
You'd better check an archived thread called
"FEMA: The Dark Underbelly" right here on FR. I did some research right before the Y2K scare that wasn't. But it wasn't because of FEMA. They have a black bag budget that is not subject to congressional overview and their organization is VERY well structured. I saw them in action here in south Florida after Hurricane Andrew.
It was reported in the Miami Herald in 1998 that the former Homestead AFB was converted to immediate use as a detention camp with FEMA as oversight even over the objections of local community leaders. It was also reported in that same article that the base is part of a string of such camps nationwide for use in "emergencies" of a nonspecified nature. Do another FR archive search and look up something called REX 84---a plan for the future use of FEMA as an "interim national authority" in case of terror attack. Written during the Presidency of Ronald Reagan by LTC Oliver North.