This concept probably has more definitions than the terms. A lot is determined by the context.
Disaster: “…a disaster is a singular event that results in widespread losses to people, infrastructure, or the environment. Disasters originate from many sources, just as hazards do (natural systems, social systems, technology failures). (Cutter 2001, 3)
Disaster: “An event in which a community undergoes severe danger and incurs, or is threatened to incur, such losses to persons and/or property that the resources available within the community are exceeded. In disasters, resources from beyond the local jurisdiction, that is State or Federal level, are required to meet the disaster demands.” (Drabek 1996, 2-4)
Disaster: “A disaster is a normatively defined occasion in a community when extraordinary efforts are taken to protect and benefit some social resource whose existence is perceived as threatened” (Dynes 1998, 113).
Disaster: Differentiating a disaster from an accident “is the extensiveness of the involvement of organizations and other segments within the community…In a community disaster, the pattern of damage may extend to several different places in the community rather than being focalized as it is within a community accident. Also, a number of community structures, perhaps including those that might house the traditional emergency organizations, might be damaged or destroyed….The increased involvement of other nonemergency organizations then creates the need for coordination of activity and for new patterns of communication among parts of the community that previously had no reason to communicate” (Dynes 1998, 119).
Disaster: “What is a disaster anyway? In social science usage as well as in everyday speech…it is a sharp and furious eruption of some kind that splinters the silence for one terrible moment and then goes away. A Disaster is an ‘event’ with a distinct beginning and a distinct end, and it is by definition extraordinary – a freak of nature, a perversion of the natural processes of life…the two distinguishing properties of a disaster are, first, that it does a good deal of harm, and, second, that it is sudden, unexpected, acute.” (Erikson 1976, 253)