FEMA has a web site dedicated to the past sixty-one years of disaster declarations – http://www.fema.gov/disasters. The site has limited information about the 3,567 Major Disaster Declarations, Emergency Declarations, and Fire Management Assistance Declarations from 1953 to today. The data provides the date, US State and type of disaster.
The law governing declarations is the Stafford Act of 1988, which in turn is based on the Disaster Relief Act of 1974. The governor of any affected US State can seek a presidential declaration of a disaster.
The key consideration is that the combined capabilities of local, county and state resources are not sufficient to ensure a timely and adequate recovery. FEMA reviews the request, evaluates the preliminary damage assessment and provides the President with a recommendation. The criteria can be subjective, and in fact the law intends for the criteria to be subjective in order to take into account unique, unexpected situations and conditions.
Disaster declarations begin at the state level. Each governor has to request the declaration for their state. For Hurricane Sandy, there were major disaster declarations for thirteen states, while for Hurricane Katrina the major disaster declaration was four states – Louisiana, Alabama, Mississippi and Florida, and emergency declarations for forty three states, including these four.
The following graph shows the disaster declarations by year since 1953 (includes Major Disaster Declarations, Emergency Declarations and Fire Management Assistance Declarations).
Analyzing the data for disaster declarations by month shows the five summer months to have about twice as many disasters as the rest of the year â€“ an average of 6.5 per month each year versus 3.7 per month each year for the rest of the year. September is the leader with 449 disaster declarations â€“ an average of 7.4 disaster declaration per year. Hurricanes are also most prevalent in September â€“ almost half of all major hurricanes over the past hundred years have occurred in September. An excellent report on US Hurricanes is provided in NOAA Technical Memorandum NWS NHC-6 (The Deadliest, Costliest, and Most Intense United States Tropical Cyclones from 1851 to 2010, and Other Frequently Requested Hurricane Facts) [download pdf]
Looking through this data, the two conclusions are the parabolic rise in federally declared disasters and the pattern for the occurrence of these events by month. Analyzing the trends from FEMA and other data can give the emergency management community some sense of the cycles they can expect, even as the impact grows nation-wide (and indeed globally, with policy consequences for NGO and disaster assistance communities).