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.

Many local areas use emergency population warnings to advise of prison escapes, abducted children, Emergency telephone number outages, and other events.

Requirements
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.

Despite the fears of many that alerts will panic the populace, evidence from the United States's use of the Emergency Alert System and its predecessor, the Emergency Broadcast System, show that this is almost unheard of. Both broadcasters and viewers are far more likely to ignore warnings than they are to panic over them. A tsunami warning may even prompt some recipients to visit the seashore.

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.

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 and cellphone text message.

France


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 the 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) #90-394, which was enacted on May 11, 1990. It consists in a modulated sound going up and down during the first minute, and repeated three times. The end of alert is a continuous signal lasting 30 seconds.



For an elecronic siren, the modulated signal consists in 4-second cycles: the sound rises from a frequency of 300 Hz (between D and D#) to 600 Hz (same sound, one octave higher) the first two seconds, then goes back to 300 Hz for the next two seconds. The signal sounds repeatedly 15 times during a one-minute period.

For an electromechanic system, the motor is switched on the first seven seconds, reaching 380 Hz (between F# and G), then turned off for five seconds, repeated five times in a one-minute period

In both cases, the end of the alert is a 380 Hz sound.

The system is tested every month, the first Wednesday at 12 noon; for tests, the modulated signal is played only once.

When the warning signal sounds, people are expected to remain at home or the building they are in and listen to further instructions on radio via France Info, France Inter, or local stations.

Instructions may also be announced by police or fire department vehicles.

Canada
As of January 2007 Canada does not have a national emergency population warning system. The private company Pelmorex, which owns Canada's two major weather networks, has proposed a national warning system which would be called All Channel Alert. This would work like the American EAS. Pelmorex's proposal has yet to be decided on by the Canadian Radio-television and Telecommunications Commission, Canada's national broadcast regulator.

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.

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 managed by and 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.

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