Cover Image
close this bookAn Overview of Disaster Management (Department of Humanitarian Affairs/United Nations Disaster Relief Office - United Nations Development Programme , 1992, 136 p.)
close this folderChapter 4. Natural hazards
View the document(introduction...)
Open this folder and view contentsCharacteristics of particular hazards and disasters 1


In earlier chapters, the discussion about disasters and emergencies resulting from natural and human-made hazards has been developed in general terms. However, each hazard has its own characteristics. To understand the significance and implications of a particular type of disaster we must have a basic understanding about the nature, causes and effects of each hazard type.

The list of hazard types is very long. Many occur infrequently or impact a very small population. Other hazards, such as severe snowstorms, often occur in areas that are prepared to deal with them and seldom become disasters. However, from the perspective of a disaster victim it is not particularly useful to distinguish between minor and major disasters. Some disasters are now of limited interest to the international community. These include avalanches, fog, frost, hail, lightning, snowstorms, and tornadoes. The international interest is less for these hazards because their impacts affect relatively few people and the countries in which they normally occur have sufficient resources and systems in place to respond without external assistance.

There are several hazard types for which there is widespread concern. They can be categorized as follows:

Sudden onset hazards - (geological and climatic hazards) earthquakes, tsunamis, floods, tropical storms, volcanic eruptions, landslides

Slow onset hazards - (environmental hazards) drought, famine, environmental degradation, desertification, deforestation, pest infestation

Industrial/technological - system failures/accidents, spillages, explosions, fires

Wars and civil strife - armed agression, insurgency, terrorism, and other actions leading to displaced persons and refugees

Epidemics - water and/or food-borne diseases, person-to-person diseases (contact and respiratory spread), vector-borne diseases and complications from wounds

These hazard types are highlighted in this training material. The international community has an interest in them because they frequently affect large populations and the need for outside assistance is evident. Many disasters are themselves international events and have an impact on entire regions.

A brief description of each hazard type is presented below. It will be your responsibility to determine which hazards are of concern to your country and then to read the material about them.

Q. Which hazards are of concern to your country?

A. List the most important hazards in order of their severity of impact.
1. ___________________________________________________________

2. ___________________________________________________________
3. ___________________________________________________________
4. ___________________________________________________________

Now learn more about each of these hazards in the material that follows.

Geological Hazards



Volcanic eruptions


Climatic Hazards

Tropical cyclones



Environmental Hazards

Environmental pollution



Pest Infestation


Industrial Accidents