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This glossary lists the disaster management terms as used in the UNDP/UNDRO Disaster Management Manual. Different usages which UNDP and other users of this manual might encounter in other documents are mentioned in the definitions as necessary.


(Post-disaster) (sometimes Damage and Needs Assessment)

The process of determining the impact of a disaster or events on a society, the needs for immediate, emergency measures to save and sustain the lives of survivors, and the possibilities for expediting recovery and development.


Damage assessment

The preparation of specific, quantified estimates of physical damage resulting from a disaster, and recommendations concerning the repair, reconstruction or replacement of structures, equipment, and the restoration of economic (including agricultural) activities.


The occurrence of a sudden or major misfortune which disrupts the basic fabric and normal functioning of a society (or community). An event or series of events which gives rise to casualties and/or damage or loss of property, infrastructure, essential services or means of livelihood on a scale which is beyond the normal capacity of the affected communities to cope with unaided.

Disaster is sometimes also used to describe a catastrophic situation in which the normal patterns of life (or eco-systems) have been disrupted and extraordinary, emergency interventions are required to save and preserve human lives and/or the environment. Disasters are frequently categorized according to their perceived causes and speed of impact. [See: Sudden natural disasters; Slow-onset disasters; Technological disasters; Human-made disasters]

Disaster management

A collective term encompassing all aspects of planning for and responding to disasters, including both pre- and post-disaster activities. It refers to the management of both the risks and the consequences of disasters.

Disaster mitigation

A collective term used to encompass all activities undertaken in anticipation of the occurrence of a potentially disasterous event, including preparedness and long-term risk reduction measures.

The process of planning and implementing measures to reduce the risks associated with known natural and man-made hazards and to deal with disasters which do occur. Strategies and specific measures are designed on the basis of risk assessments and political decisions concerning the levels of risk which are considered to be acceptable and the resources to be allocated (by the national and sub-national authorities and external donors).

Mitigation has been used by some institutions/authors in a narrower sense, excluding preparedness. It has occasionally been defined to include post-disaster response, then being equivalent to disaster management, as defined in this glossary.

Disaster preparedness

Measures that ensure the readiness and ability of a society to (a) forecast and take precautionary measures in advance of an imminent threat (in cases where advance warnings are possible), and (b) respond to and cope with the effects of a disaster by organizing and delivering timely and effective rescue, relief and other appropriate post-disaster assistance.

Preparedness involves the development and regular testing of warning systems (linked to forecasting systems) and plans for evacuation or other measures to be taken during a disaster alert period to minimize potential loss of life and physical damage; the education and training of officials and the population at risk; the establishment of policies, standards, organizational arrangements and operational plans to be applied following a disaster impact; the securing of resources (possibly including the stockpiling of supplies and the earmarking of funds); and the training of intervention teams. It must be supported by enabling legislation.

Expected losses/effects

The expected number of lives lost, persons injured, damage to property and disruption of essential services and economic activity due to the impact of a particular natural or man-made hazard. It includes physical, social/functional and economic effects.

Famine early warning

The process of monitoring the situation in areas known to be particularly vulnerable to the effects of droughts, crop failures, or changes in economic conditions, to enable remedial measures to be initiated before hardship becomes acute.


(or hazardous phenomenon or event)

A rare or extreme event in the natural or man-made environment that adversely affects human life, property or activity to the extent of causing disaster.

A hazard is a natural or man-made phenomenon which may cause physical damage, economic losses, or threaten human life and well-being if it occurs in an area of human settlement, agricultural, or industrial activity.

Note, however, that in engineering, the term is used in a more specific, mathematical sense to mean the probability of the occurrence, within a specified period of time and a given area, of a particular, potentially damaging phenomenon of a given severity/intensity.

Hazard assessment
(sometimes hazard analysis/evaluation)

The process of estimating, for defined areas, the probabilities of the occurrence of potentially-damaging phenomenon of given magnitudes within a specified period of time.

Hazard assessment involves analysis of formal and informal historical records, and skilled interpretation of existing topographical, geological, geomorphologi-cal, hydrological, and land-use maps.

Hazard mapping

The process of establishing geographically where and to what extent particular phenomena are likely to pose a threat to people, property, infrastructure, and economic activities.

Hazard mapping represents the result of hazard assessment on a map, showing the frequency/probability of occurrences of various magnitudes or durations.

Human-made disasters

Disasters or emergency situations of which the principal, direct causes are identifiable human actions, deliberate or otherwise. Apart from “technological disasters,” this mainly involves situations in which civilian populations suffer casualties, losses of property, basic services, and means of livelihood as a result of war, civil strife, or other conflict.

In many cases, people are forced to leave their homes, giving rise to congregations of refugees or externally or internally displaced persons.

Human-made hazard

A condition which may have disastrous consequences for a society. It derives from technological processes, human interactions with the environment, or relationships within and between communities.

Natural hazard

Natural phenomena which occur in proximity and pose a threat to people, structures or economic assets and may cause disaster. They are caused by biological, geological, seismic, hydrological, or meteorological conditions or processes in the natural environment.



Reconstruction must be fully integrated into ongoing long-term development plans taking into account of future disaster risks and possibilities to reduce those risks by the incorporation of appropriate mitigation measures. Damaged structures and services may not necessarily be restored in their previous form or locations. It may include the replacement of any temporary arrangements established as a part of emergency response or rehabilitation.


For engineering purposes, risk is defined as the expected losses (lives lost, persons injured, damage to property, and disruption of economic activity) caused by a particular phenomenon. Risk is a function of the probability of particular occurrences and the losses each would cause. Other analysts use the term to mean the probability of a disaster occurring and resulting in a particular level of loss.

A societal element is said to be “at risk”, or “vulnerable”, when it is exposed to known disaster hazards and is likely to be adversely affected by the impact of those hazards if and when they occur. The communities, structures, services, or activities concerned are described as “elements at risk.”

Risk assessment

(sometimes risk analysis)

The process of determining the nature and scale of the losses (due to disasters) which can be anticipated in particular areas during a specified time period.

Risk assessment involves an analysis and combination of both theoretical and empirical data concerning: the probabilities of known disaster hazards of particular force or intensities occurring in each area (“hazard mapping”); and the losses (both physical and functional) expected to result to each element at risk in each area from the impact of each potential disaster hazard (“vulnerability analysis” and “expected loss estimation”).

Risk mapping

The presentation of the results of risk assessment on a map, showing the levels of expected losses which can be anticipated in specific areas, during a particular time period, as a result of particular disaster hazards.

Risk reduction (long-term)

Long-term measures to reduce the scale and/or the duration eventual adverse effects of unavoidable or unpreventable disaster hazards on a society which is at risk, by reducing the vulnerability of its people, structures, services and economic activities to the impact of known disaster hazards.

Typical risk reduction measures include improved building standards, flood plain zoning and land-use planning, crop diversification, and planting wind-breaks. The measures are frequently sub-divided into “structural” and “non-structural”, “active” and “passive” measures.

N.B. A number of sources have used “disaster mitigation” in this context, while others have used “disaster prevention”.

Slow-onset disasters

(Sometimes Creeping Disasters or Slow-onset Emergencies)

Situations in which the ability of people to acquire food and other necessities of life slowly declines to a point where survival is ultimately jeopardized. Such situations are typically brought on or precipitated by drought, crop failure, pest diseases, or other forms of “ecological” disaster, or neglect.

If detected early enough, remedial action can be taken to prevent excessive human distress or suffering occurring. However, if neglected, the result can be widespread destitution and suffering, and a need for emergency humanitarianism assistance as in the aftermath of sudden disasters.

Sudden natural disasters

Sudden calamities caused by natural phenomena such as earthquakes, floods, tropical storms, or volcanic eruptions. They strike with little or no warning and have an immediate adverse impact on human populations, activities, and economic systems.