J-Alert (; full name ) is the

early warning system An early warning system is a warning system that can be implemented as a chain of information communication systems and comprises sensors, event detection and decision subsystems for early identification of hazards. They work together to fore ...

used in

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

. J-Alert was launched in February 2007. The system is designed to quickly inform the public of threats and emergencies such as

earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

s, severe weather, and other dangers. The system was developed in the hope that early warnings would speed up evacuation times and help coordinate emergency response.

System

J-Alert is a

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

based system that allows authorities to quickly broadcast alerts to local

media Media may refer to: Communication * Means of communication, tools and channels used to deliver information or data ** Advertising media, various media, content, buying and placement for advertising ** Interactive media, media that is inter ...

and to

citizen Citizenship is a membership and allegiance to a sovereign state. Though citizenship is often conflated with nationality in today's English-speaking world, international law does not usually use the term ''citizenship'' to refer to nationality ...

s directly via a system of nationwide

loudspeaker A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an ...

television Television (TV) is a telecommunication medium for transmitting moving images and sound. Additionally, the term can refer to a physical television set rather than the medium of transmission. Television is a mass medium for advertising, ...

radio Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connec ...

email Electronic mail (usually shortened to email; alternatively hyphenated e-mail) is a method of transmitting and receiving Digital media, digital messages using electronics, electronic devices over a computer network. It was conceived in the ...

, and

cell broadcast Cell Broadcast (CB) is a method of simultaneously sending Short Message Service, short messages to multiple mobile telephone users in a defined area. It is defined by the ETSI's GSM committee and 3GPP and is part of the 2G, 3G, 4G and 5G standa ...

s. According to Japanese officials, it takes about one second to inform local officials, and between four and twenty seconds to relay the message to citizens. An enhanced version of the J-Alert receivers were installed by the end of March 2019. The new models can automatically process the information within two seconds, compared to the older models that can take up to twenty seconds. J-Alert broadcasts via both ground systems and the Superbird-B3 communication satellite. When there is a civil emergency such as a ballistic missile heading towards Japan, a siren called Civil Protection Siren sounds across loudspeakers.

Information transmission capabilities

Earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

Earthquake Early Warning An earthquake early warning (EEW) system is a system of accelerometers, seismometers, communication, computers, and alarms that is devised for rapidly notifying adjoining regions of a substantial earthquake once one begins. This is not the same ...

**Quick updates on

hypocenter A hypocenter or hypocentre (), also called ground zero or surface zero, is the point on the Earth's surface directly below a nuclear explosion, meteor air burst, or other mid-air explosion. In seismology, the hypocenter of an earthquake is its ...

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

, and precautions of possible tsunami **Information of

, intensities of various areas, and the presence of

tsunami A tsunami ( ; from , ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and underwater explosions (including detonations, ...

**Earthquake prediction warning for the

Tōkai earthquakes The Tōkai earthquakes () are major earthquakes that have occurred regularly with a return period of 100 to 150 years in the Tōkai region of Japan. The Tōkai segment has been struck by earthquakes in 1498, 1605, 1707, and 1854. Given the histor ...

**Earthquake prediction advisory information of the Tōkai earthquakes **Earthquake prediction information of the Tōkai earthquakes *

Tsunami A tsunami ( ; from , ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and underwater explosions (including detonations, ...

**Major tsunami warning ** Tsunami warning ** Tsunami advisory * Volcano eruption **Emergency warning of volcanic eruption and the possibility of eruption **Warning of volcanic eruption and the possibility of eruption **Volcanic crater forecast *Severe weather **Emergency warnings for heavy rain, heavy snow, gale,

snowstorm A winter storm (also known as snow storm) is an event in which wind coincides with varieties of precipitation that only occur at freezing temperatures, such as snow, Rain and snow mixed, mixed snow and rain, or freezing rain. In Continental cl ...

waves United States Naval Reserve (Women's Reserve), better known as the WAVES (for Women Accepted for Volunteer Emergency Service), was the women's branch of the United States Naval Reserve during World War II. It was established on July 21, 1942, ...

, and storm surge **Warnings for heavy rain, heavy snow,

gale A gale is a strong wind; the word is typically used as a descriptor in nautical contexts. The U.S. National Weather Service defines a gale as sustained surface wind moving at a speed between .

, and storm surge **Weather advisory **Information of the risk of

landslides Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslide ...

**Advisory information for

tornado A tornado is a violently rotating column of air that is in contact with the surface of Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the ...

**Information of violent heavy rain **Flood forecast *Special emergency threats **Information of

ballistic missile A ballistic missile is a type of missile that uses projectile motion to deliver warheads on a target. These weapons are powered only during relatively brief periods—most of the flight is unpowered. Short-range ballistic missiles (SRBM) typic ...

s **Information of airstrikes **Information of

guerrilla Guerrilla warfare is a form of unconventional warfare in which small groups of irregular military, such as rebels, Partisan (military), partisans, paramilitary personnel or armed civilians, which may include Children in the military, recruite ...

and

special forces Special forces or special operations forces (SOF) are military units trained to conduct special operations. NATO has defined special operations as "military activities conducted by specially designated, organized, selected, trained and equip ...

attacks **Information of large-scale

terrorism Terrorism, in its broadest sense, is the use of violence against non-combatants to achieve political or ideological aims. The term is used in this regard primarily to refer to intentional violence during peacetime or in the context of war aga ...

**Other information for civil and national defense

Adoption rate

Many prefectures and

urban area An urban area is a human settlement with a high population density and an infrastructure of built environment. Urban areas originate through urbanization, and researchers categorize them as cities, towns, conurbations or suburbs. In urbani ...

s were slow in adopting the system. Upon its introduction, the Japanese government hoped to have 80% of the country equipped with the J-Alert system by 2009. However, by 2011, only 36% of the nation had been covered. Cost had been a major factor; the initial installation is estimated to be around 430 million

yen The is the official currency of Japan. It is the third-most traded currency in the foreign exchange market, after the United States dollar and the euro. It is also widely used as a third reserve currency after the US dollar and the euro. T ...

, and the yearly maintenance is estimated to be around 10 million

. By May 2013, 99.6% of municipalities nationwide were covered.

Notable instances

* On 13 April 2023, a

North Korea North Korea, officially the Democratic People's Republic of Korea (DPRK), is a country in East Asia. It constitutes the northern half of the Korea, Korean Peninsula and borders China and Russia to the north at the Yalu River, Yalu (Amnok) an ...

n missile launch warning led residents to take cover from debris that most likely fell into the sea hundreds of miles away. The alert, just before 8 a.m., triggered sirens on

Hokkaido is the list of islands of Japan by area, second-largest island of Japan and comprises the largest and northernmost prefectures of Japan, prefecture, making up its own list of regions of Japan, region. The Tsugaru Strait separates Hokkaidō fr ...

and sent automated messages to mobile phones in J-Alert urging the northern island's more than five million residents to seek immediate shelter, after

Pyongyang Pyongyang () is the Capital city, capital and largest city of North Korea, where it is sometimes labeled as the "Capital of the Revolution" (). Pyongyang is located on the Taedong River about upstream from its mouth on the Yellow Sea. Accordi ...

fired a new type of ballistic missile.

References

External links

J-Alert Overview

Fire and Disaster Management Agency The (FDMA) is an external agency attached to the Ministry of Internal Affairs and Communications in Japan. Background The Fire and Disaster Management Agency was established through article 3 paragraph 2 of the 1948 National Government Organizat ...

Ministry of Internal Affairs and Communications The is a Cabinet (government), cabinet-level ministry in the Government of Japan. Its English name was Ministry of Public Management, Home Affairs, Posts and Telecommunications (MPHPT) prior to 2004. It is housed in the 2nd Building of the Centr ...

国民保護室・国民保護運用室

北朝鮮から発射された弾道ミサイルが日本に飛来する可能性がある場合における全国瞬時警報システム（Jアラート）による情報伝達について
Cabinet Secretariat Civil Protection
全国瞬時警報システム（J-ALERT）の整備

Guide on disaster prevention and mitigation effort during earthquakes and tsunamis

Japan Meteorological Agency The Japan Meteorological Agency (JMA; ''気象庁, Kishō-chō'') is a division of the Ministry of Land, Infrastructure, Transport and Tourism dedicated to the Scientific, scientific observation and research of natural phenomena. Headquartered ...

Protecting guide against Armed Attacks or Terrorism
Cabinet Secretariat Civil Protection
全国瞬時警報システム実際の放送例 (J-Alert Demonstration)

YouTube YouTube is an American social media and online video sharing platform owned by Google. YouTube was founded on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim who were three former employees of PayPal. Headquartered in ...

{{Cell Broadcast System Emergency management in Japan Emergency population warning systems 2007 establishments in Japan 2007 introductions