Hazard, Definition of

Definition of Hazard

According to terminology suggested by the United Nations International Strategy for Disaster Reduction (UNISDR) on disaster risk reduction in 2009, a hazard is defined as a dangerous phenomenon, substance, human activity, or condition that may cause loss of life, injury, or other health impacts; property damage; loss of livelihoods and services; social and economic disruption; or environmental damage. Such hazards arise from a variety of geological, meteorological, hydrological, oceanic, biological, and technological sources, sometimes acting in combination. In technical settings, hazards are described quantitatively by the likely frequency of occurrence of different intensities for different areas, as determined from historical data or scientific analysis.

Statistically, hazard is defined as the probability of occurrence of a potentially damaging event, process, activity, or condition of given characteristics in a given space and time. Besides the probability of occurrence, the characteristics of the hazard are described by its physical dimensions, including location, magnitude (mostly defined in terms of energy released), duration of occurrence and impact (the period), geographical extent, frequency (how often it occurs), intensity, timing of occurrence, and speed of onset (how fast or slowly it occurs). Hazard is not deemed to be synonymous with risk, although it is an important determinant of risk. Hazard is actually the potential to cause harm, whereas risk is the likelihood of harm in defined circumstances. The degree of risk [Page 442]depends upon the degree of exposure and vulnerability of the element exposed to a given hazard. A low exposure to something that is highly hazardous may result in a low risk, whereas a high exposure to something of low hazard may result in moderate or even high risk.

A widely accepted definition characterizes natural hazards as “those elements of the physical environment, harmful to human beings and caused by forces extraneous to him/her.” The term natural hazards refers to all atmospheric, hydrologic, geologic, and wildfire phenomena that, because of their location, severity, and frequency, have the potential to affect humans, structures, and activities adversely. The probability of occurrence of hazards depends on certain causative factors and conditions that can be identified and assessed for disaster risk management. However, such hazard identification and assessment will have some uncertainty, which should be informed while expressing the results. The factors affecting the occurrence of hazards may be inherent or acquired.

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