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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
close this folderCharacteristics of particular hazards and disasters 1
View the document(introduction...)
View the documentEarthquakes
View the documentTsunamis
View the documentVolcanoes
View the documentLandslides
View the documentTropical cyclones
View the documentFloods
View the documentDroughts
View the documentEnvironmental pollution
View the documentDeforestation
View the documentDesertification
View the documentPest infestations
View the documentEpidemics
View the documentChemical and industrial accidents


Causal phenomena

Slippage of crustal rock along a fault or area of strain and rebound to new alignment.

General characteristics and effects

Shaking of earth caused by waves on and below the earth’s surface causing:

Surface faulting
Tremors, vibrations


Probability of occurrence can be determined but not exact timing. Forecasting is based on monitoring of seismic activity, historical incidence, and observations.

Factors contributing to vulnerability

Location of settlements in seismic areas.
Structures which are not resistant to ground motion.
Dense collections of buildings with high occupancy.
Lack of access to information about earthquake risks.

Typical adverse effects

Physical damage - Damage or loss of structures or infrastructure. Fires, dam failures, landslides, flooding may occur.
Casualties - Often high, particularly near epicenter or in highly populated areas or where buildings not resistant.
Public health - Fracture injuries most widespread problem. Secondary threats due to flooding, contaminated water supply, or breakdown in sanitary conditions.
Water supply - Severe problems likely due to damage of water systems, pollution of open wells and changes in water table.

Possible risk reduction measures

Hazard mapping
Public awareness programs and training
Assessing and reducing structural vulnerability
Land use control or zoning, building codes

Specific preparedness measures

Earthquake warning and preparedness programs

Typical post-disaster needs

Search and rescue
Emergency medical assistance
Damage needs and assessment survey
Relief assistance
Repair and reconstruction
Economic recovery

Impact assessment tools

Earthquake scales (Modified Mercalli, MSK), earthquake damage and usability forms.