Impact, Definition of

In the last half of the 20th century, there were increases of 250 percent in the number of recorded disasters, 500 percent in both the number of mass-casualty disasters and the number of people affected by disaster, 1,500 percent in the cost of disasters, and 1,640 percent in insurance reimbursement as a result of disaster, according to the 2000 data compiled by the Munich Re Insurance Company. These trends have continued unabated into the 21st century. However, they are somewhat exaggerated, because in 1950 the collection of statistics on disaster impacts was rudimentary. Moreover, only direct costs were measured, whereas now indirect costs are taken into account. Nevertheless, in 60 years there have been large increases in population and accumulations of capital investment in major hazards zones, especially along coastlines subject to hurricanes, flooding, and potentially sea level rise. Everywhere, the increase in global connectivity and technological complexity has caused vulnerability to disasters to rise and thus has made impacts more profound and complex.

When disaster strikes, these are the principal categories of impact: death, physical and psychological injury, disease outbreaks and other medical conditions, destruction of property and physical damage, economic effects and impacts upon livelihoods, and disruption of normal activities. As measured in the time taken to rebuild physical structures and fully restore normal activities, the impact of a major disaster may last for 10–25 years, depending on the severity of the event, the size of the area affected, and the resources available over time for recovery. There is increasing recognition that the restoration of livelihoods and local economic activities, preferably with democratic participation in decision making (i.e., good, transparent governance), is the key to recovery from disaster.

For convenience of recognition and analysis, the causes of disasters are usually divided into five categories:

• Natural: such as earthquakes, floods, hurricanes, landslides
• Technological: such as toxic spills, chronic pollution episodes, transportation crashes
• Social: such as strikes, demonstrations, riots, mass gatherings
• Intentional: such as terrorist attacks, hostage taking
• Compound or complex: combinations of the above, such as “na-tech” (natural-technological) disasters

The distinctions are somewhat artificial. To begin with, natural phenomena are not necessarily inherently disastrous. As the human propensity to [Page 488]put oneself at risk is paramount, and thus vulnerability is the root cause of many natural disasters, the word natural is more a convenience term than a robust descriptor. Moreover, there are many process-based links between the categories. For instance, natural disasters may affect technological capital, technology may abate or increase vulnerability to natural disasters, natural disasters may affect social stability, social conditions may help incubate dissidence and thus foster intentional disasters, and terrorism has a technological component.

As Table 1 shows, there are grounds for creating a semantic classification of the size of event on the basis of its geographical extent, its complexity, the nature of the emergency response required, and the degree of involvement of public authorities and the affected population. However, the distinctions between an incident, a major incident, a disaster, and a catastrophe are purely notional: they cannot easily be quantified, and they are not accepted by all of the protagonists in this field. Moreover, other distinctions need to be added to the classification. One of these is between sudden impact events and “creeping” disasters, or slow-onset events. Among the latter, accelerated soil erosion may eventually cause disastrous damage to structures and local food production, but it may take decades to arrive at that point. The sudden-onset disasters vary according to their degree of predictability and forewarning: most earthquakes occur virtually without warning, while storms allow varied propensities for meteorological forecasting that grant lead time for preparation to meet the impact, for example, by sheltering from tornadoes or evacuating in advance of hurricanes. Nonetheless, as Table 2 illustrates, the best way to distinguish size of event is probably in relation to the thresholds of capacity to cope with it at each level of civil administration.

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