Federal Signal took advantage of this design and created their Thunderbolt Siren Series, utilizing Sutorbilt Roots Blowers of different varieties and outputs.

[citation needed] Electronic sirens may be mechanically rotated to cover a wide area, or may have transducers facing in all directions to make an omnidirectional pattern.

Individuals must go to shelters or their homes, lock doors and windows, take appropriate protective actions, and listen through the radio and television for instructions of civil defense.

They sound-off during the memorial of Atatürk's death on November 10 at 9:05 AM and often sound off for common emergencies such as Earthquakes, Tsunamis, Tornadoes, Chemical plant issues or incoming enemy attack.

On 2 June every year, the day of Hristo Botev and demised ones for the liberation and independence of Bulgaria is commemorated with a two-minute signal, different from the usual tone.

The sirens are mainly electronic ones (German made type ECN units or other high powered speaker systems on top of public buildings).

[citation needed] In Germany, the Warnämter ('warning authorities') were closed in the 1990s after the threat of the Cold War was over, since the ability to alert the public was then considered unnecessary.

In the 2000s, it was realized that the ability to warn the public is not only necessary in cases of war, but also in events like natural disasters, chemical or nuclear accidents, or terrorist attacks.

The electric sirens were controlled via phone lines and were operated from a central location, such as a city hall, fire station, post office, or local military base or outpost.

In the mid 2000s, the MoLaRi System was built around factories that work with hazardous materials, to warn surrounding areas in case of emergency or risk to public health or safety.

By order of the MPVO headquarters, the duty officer of the Central station of the radio network interrupted the broadcast of the program, turned on an electric player with a record of the alarm text.

The municipalities of Muta, Vuzenica, Podvelka, Radlje ob Dravi, Brežice, Krško and Sevnica use a 100-second-long wailing signal (named Neposredna nevarnost poplavnega vala) (consisting of four-second bursts separated by four seconds of silence) for the immediate danger of flash floods, used in case of overflow or collapse of a hydroelectric dam.

[citation needed] The Swedish alarm system uses outdoor sirens in addition to information transmitted through radio and television and sent by text messages and mobile apps.

The most common cause of general alarms is fire, specially in situations that involve industries, landfills, and other facilities containing dangerous substances which can create hazardous smoke.

[56] Audio sample of signal "Important public announcement" recorded in Stockholm, 6 March 2017ⓘ Switzerland currently has 8,500 mobile and stationary civil defense sirens, which can alert 99% of the population.

[citation needed] Every village, town, and city in the United Kingdom used to have a network of dual-tone sirens to warn of incoming air raids during World War II.

In 2008, a review of the current and future role of flood warning sirens was undertaken by Norfolk County Council, after plans to retire them were halted following concerns from nearby residents.

[77] Emergency planners had proposed to use a new warning system that would contact residents by telephone; however, this was abandoned due to technical limitations and local media and other communication methods are used instead.

Following severe flooding in Upper Calder Valley in June 2000, the Environment Agency replaced its network of sirens, with eight being placed around Walsden, Todmorden, Hebden Bridge and Mytholmroyd.

In November 2010, 36 flood warning sirens in Essex, including nine on Canvey, were retired following concerns from the county council that the system was "no longer fit for purpose".

[86] In June 2016, the West London Mental Health Trust, who manages the hospital, proposed decommissioning the sirens altogether and replacing them with social media alerts through websites such as Twitter.

In Canada, a nationwide network of Canadian Line Materials sirens was established in the 1950s to warn urban populations of a possible Soviet nuclear attack.

In the dry areas of the American West, residents may be required to shut off outdoor water systems to ensure adequate pressure at fire hydrants upon hearing the signal.

Some communities, particularly in New England and northern California, make use of coded blasts over a diaphone or air horn for fire signals, reserving the use of sirens for more serious situations.

This is typically a one-second burst of sound to verify the proper operation of the siren without causing a significant number of people to interpret the test as an actual alert.

In Pierce County, Washington there is a system of sirens set up along the Puyallup and Carbon River valleys to warn residents of volcanic eruptions and lahars (giant mudslides) from Mt.

[102] Sirens in the United States have been replaced by NOAA Weather Radios for advance warnings about future severe storms whenever people are inside cars or buildings.

In Victoria, many Country Fire Authority stations have sirens installed that are used to summon volunteers to an emergency callout, as well as consequently alerting the local community of brigade activity.

[110] In the years following the tsunamis of the Indian Ocean earthquake in 2004, Meerkat electronic sirens were installed in all populated areas of the west coast lower than 10 metres.

Morocco, like many other countries, has civil defense sirens installed in several cities and towns such as Casablanca, Oujda, Asilah, M'diq, Chefchaouen, and Qalaat Sraghna.