Emergency population warning
An emergency population warning is a method whereby local, regional, or national authorities can contact members of the public en masse to warn them of an impending emergency. These warnings may be necessary for a number of reasons, including:
- weather emergencies such as tornadoes, hurricanes, and ice storms;
- 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; and
- warfare or acts of terrorism.
In order to develop an effective emergency warning system, certain things are required:
- an agreement as to what constitutes an emergency in the area served by the system. This differs from region to region depending on the local climate, geology, and the like.
- an agreement as to who can initiate an alert. In some countries all warnings are transmitted by a single command center, while in others (such as the United States) a host of local, regional, and national agencies are authorized to initiate warnings.
- a system or systems by which the information can be quickly transmitted to the population.
- an education program to teach the general public how to recognize an alert or what to do if a warning is broadcast.
United Nations program 
The United Nations relies on the Everbridge Aware emergency notification system (ENS) to alert its 10,000 staff to address their safety and security when a critical incident or event occurs.
The United Nations Development Programme uses the Send Word Now Emergency Notification System to alert its worldwide staff when an urgent situation arises.
Methods by country 
As of January 2007 Canada does not have a national emergency population warning system. The private company Pelmorex, which owns Canada's two major cable weather networks (The Weather Network and MétéoMédia), has proposed a national warning system which would be called All Channel Alert. This would work like the American EAS. On June 11, 2009, the CRTC gave Pelmorex full approval of the service, which will serve to complement efforts set forth by the federal government, as well as provincial and local governments.
The Canadian government is currently working on a proposed national public alerting system under the name CANALERT. It is expected that this system will work closely with private broadcasters and telecommunications operators to enable an all-hazards, all-media warning system based on the Common Alerting Protocol information standard.
As of November 2010, both All Channel Alert and CANALERT has yet to be launched.
The province of Alberta has its own system called the Emergency Public Warning System (EPWS). The EPWS was put into place after a major tornado swept through the city of Edmonton in 1987, killing 27 and causing millions of dollars in damage. Unlike the American EAS, however, broadcast of the EPWS is not mandatory on radio and television stations. It is broadcast on the CKUA Radio Network and is televised on Access TV and by co-operating stations. EPWS warnings can be initiated by municipal police and fire departments, the provincial government, county authorities, tribal government agencies, Environment Canada, and the Royal Canadian Mounted Police. CKUA developed and maintained the EPWS until January 2010, when the contract was lost to an Ottawa firm.[who?]
In France, the population warning is made via air raid siren. This network is called the "Réseau national d'alerte" (RNA). The system is inherited from the air-raid siren network (défense passive) developed before World War II. It consists of about 4,500 electronic or electromechanical sirens placed all over France.
In some cases, the warning signal may be played by a mobile system installed on the fire department's vehicles.
The warning signal is described by décret (by law) of March 23, 2007. It consists in a modulated sound going up and down (up to 380 Hz) during the first minute, and repeated three times. The end of alert is a continuous signal lasting 30 seconds.
The system is tested every month, the first Wednesday at 12 noon; for tests, the modulated signal is played only once.
Instructions may also be announced by police or fire department vehicles.
The J-Alert system launched in 2007 aims to allow government officials to address the population directly via loudspeakers. It aims to cover earthquake, tsunami, volcano, and military emergencies.
The Earthquake Early Warning system is operated by the Japan Meteorological Agency. It is capable of delivering warnings a few seconds before S-waves can propagate to distant locations. Warnings are broadcast by radio and television stations, and compatible equipment can automatically turn on when receiving a message. EEW capability is also required for all domestic cell phones sold after 2007.
JMA also issues advisories regarding tropical cyclones in the western Pacific Ocean.
South American countries 
Many countries in South America have a system called "cadena nacional" (Spanish: national broadcast). It enables the leader of the country to address the people simultaneously on all TV channels and radio stations, interrupting normal programming. The details vary: in Argentina and Venezuela, it is mandatory to broadcast the message, while in Chile it is voluntary. Many of those systems were created by past military governments.
United States 
The bulk of emergency warnings in the United States are sent through the Emergency Alert System. The EAS can be activated by national, state, regional, or local authorities, including police, fire, weather, and other governmental authorities. EAS is often activated when an unpredicted emergency such as a tornado, earthquake, or release of toxic gas happens. The vast majority of EAS alerts are generated by the National Weather Service.
The Integrated Public Alert and Warning (IPAWS) program of the U.S. Federal Emergency Management Agency is an attempt to integrate multiple public warning technologies into a coordinated nationwide "system of systems" using the Common Alerting Protocol. Systems targeted for inclusion in IPAWS include the Emergency Alert System, the Commercial Mobile Alert System using cellular telephones and other wireless devices and the NOAA Weather Radio network.
Many states use existing air raid sirens to warn of tornadoes and flash floods. People living near certain nuclear facilities such as the Hanford Site in Washington have special radios in their home that are set to broadcast a warning signal in the event of a radiological emergency. Some emergencies (AMBER Alerts, for instance) are also sent out via e-mail, cellphone text message, and highway signs. Many U.S. institutions of higher education now use multiple warning technologies on their campuses, including outdoor and indoor sirens, public address systems, email and cell phone text messaging, and digital displays.
See also 
- Emergency Alert System (United States)
- HEARO Local Alert Receiver
- Standard Emergency Warning Signal (Australia)
- Warning system (list of types)
- "UN-led global early warning system takes shape" (Press release). UN International Early Warning Programme. 26 March 2007. Retrieved 2007-08-31.
- Channel Canada: "CRTC approves carriage of The Weather Network and MétéoMédia's services, allowing for an emergency alerting system", 6/11/2009.
- Broadcasting Order CRTC 2009-340, issued 6/11/2009.
- "Contract loss forces job cuts at CKUA". www.cbc.ca. January 12, 2010. Retrieved May 20, 2010.
- Shalash, Samieh. "CNU Increasing Lockdowns, Evacuations: Drills are Part of Testing the Emergency Notification System". Daily Press.