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International Strategy for Disaster Reduction
Platform for the Promotion of Early Warning

What's early warning
Basics of early warning - How early warnings are made - Milestones and first steps of early warning

Basics of early warning

Hazards, vulnerability and disasters
Natural hazards, such as storms, droughts, volcanic eruptions, or earthquakes, need not spell disaster. A disaster occurs only if a community or population is exposed to the natural hazard and cannot cope with its effects. Torrential rain in the middle of an ocean will not cause a disaster, but the same heavy rainfall on a vulnerable population – say a shanty town on the side of a hillside stripped of trees - may result in landslides and a huge loss of life. A minor drought may cause a famine if a region’s agricultural production is highly stressed by civil war. A community that lacks an early warning system may sleep while volcanic ash clouds bear down upon them. Vulnerability is the potent additive that mixes with natural hazards to cause disasters.

More than just a prediction
A complete and effective early warning system comprises four elements, spanning a knowledge of the risks faced through to preparedness to act on early warning. Failure in any one part can mean failure of the whole system.

The Four Elements of Effective Early Warning Systems

Risk knowledge
Systematically collect data and undertake risk assessments

Are the hazards and the vulnerabilities well known? What are the patterns and trends in these factors? Are risk maps and data widely available?
Monitoring and warning service
Develop hazard monitoring and early warning services

Are the right parameters being monitored? Is there a sound scientific basis for making forecasts? Can accurate and timely warnings be generated?
Dissemination and communication
Communicate risk information and early warnings

Do warnings reach all of those at risk? Are the risks and the warnings understood? Is the warning information clear and useable
Response capability
Build national and community response capabilities

Are response plans up to date and tested? Are local capacities and knowledge made use of? Are people prepared and ready to react to warnings?

Pulling it all together
Good early warning systems have strong linkages between the four elements. The major players concerned with the different elements meet regularly to ensure they understand all of the other components and what other parties need from them. Risk scenarios are constructed and reviewed. Specific responsibilities throughout the chain are agreed and implemented. Past events are studied and improvements are made to the early warning system. Manuals and procedures are agreed and published. Communities are consulted and information is disseminated. Operational procedures such as evacuations are practiced and tested.

Behind all of these activities lies a solid base of political support, laws and regulations, institutional responsibility, and trained people. Early warning systems are established and supported as a matter of policy. Preparedness to respond is engrained in society.