Emergency population warning

An emergency population warning, or public warning system is a method where by local, regional, or national authorities can contact or notify members of the public to warn them of an impending emergency. These warnings may be necessary for a number of reasons, including:

• Weather emergencies such as cyclones, flooding, tornadoes, avalanches and severe weather.
• Geological disasters such as earthquakes, landslides, volcanic eruptions, and tsunamis.
• Industrial disasters such as the release of toxic gas or contamination of river water.
• Radiological disasters such as a nuclear plant disaster.
• Medical emergencies such as an outbreak of a fast-moving infectious disease or pandemic.
• Warfare such as air raids or acts of terrorism.
• Other events, such as prison escapes, abducted children or emergency telephone number outages.

They are often disseminated during urgent events such as evacuations or where a severe threat to life is expected.

Common alerting methods include sirens, radio, television, local media, telephone, SMS and Cell Broadcast.