Earthquake Early Warning (Japan)
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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 ...
, the is an alert that is issued when an
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 ...
is detected by multiple seismometers. These warnings are primarily issued by the
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 ...
(JMA), with guidance on how to react to them.


Introduction

The JMA has two EEW systems: one for the general public and another for the National Meteorological and Hydrological Services. When a
P-wave A P wave (primary wave or pressure wave) is one of the two main types of elastic body waves, called seismic waves in seismology. P waves travel faster than other seismic waves and hence are the first signal from an earthquake to arrive at any ...
is detected from two (or more) of the 4,235
seismometer A seismometer is an instrument that responds to ground displacement and shaking such as caused by quakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The out ...
s installed throughout Japan, the JMA analyzes and predicts the approximate location of the earthquake's
epicenter The epicenter (), epicentre, or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Determination The primary purpose of a ...
. This allows the JMA to notify people in affected
prefectures A prefecture (from the Latin word, "''praefectura"'') is an administrative jurisdiction traditionally governed by an appointed prefect. This can be a regional or local government subdivision in various countries, or a subdivision in certain inter ...
by TV and radio if a strong earthquake is expected. An Earthquake Early Warning is issued to warn the general public when an earthquake of 5 or higher on the Japan seismic scale is expected to areas where the seismic intensity is expected to be 4 or higher. An EEW forecast (緊急地震速報(予報)) is issued to the National Meteorological and Hydrological Services when an earthquake of 3 or higher on the Japan seismic scale (or 3.5 or higher on the
Richter magnitude scale The Richter scale (), also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale, is a measure of the strength of earthquakes, developed by Charles Richter in collaboration with Beno Gutenberg, and pr ...
) is expected, or when the
amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of am ...
of P- or S-waves measures more than 100 gals. The system was developed to minimize earthquake damage and enable people to take shelter or evacuate dangerous areas before the arrival of its strong surface waves. It is used by railways to slow trains and by factories to halt assembly lines before the earthquake hits. The effectiveness of the warning depends on the position of the receiver. After receiving a warning, a person has from a few seconds to a minute or more to take action. Areas near an epicenter may experience strong tremors before a warning is issued. After the
2011 Tōhoku earthquake and tsunami On 11 March 2011, at 14:46:24 Japan Standard Time, JST (05:46:24 UTC), a  9.0–9.1 Submarine earthquake, undersea megathrust earthquake occurred in the Pacific Ocean, east of the Oshika Peninsula of the Tōhoku region. It lasted approx ...
, the EEW system and Japan's tsunami warning system were considered effective. Although the tsunami killed over 10,000 people, it is believed that the casualties would have been much higher without the EEW system. In April 2011, the
Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...
an Subsecretary of Telecommunications said that their country hoped to establish a similar early-warning system.


Hit rate

The JMA announced the Earthquake Early Warning hit (accuracy) rate for the 2011
fiscal year A fiscal year (also known as a financial year, or sometimes budget year) is used in government accounting, which varies between countries, and for budget purposes. It is also used for financial reporting by businesses and other organizations. La ...
on 31 May 2012. The hit rate is the percentage of warnings issued immediately on the detection of
P-waves A P wave (primary wave or pressure wave) is one of the two main types of elastic body waves, called seismic waves in seismology. P waves travel faster than other seismic waves and hence are the first signal from an earthquake to arrive at an ...
with a number (0 to 7) within one shindo number of the measured earthquake. For the fiscal years 2007–2009, the hit rate was 75 percent or higher (75 percent in 2007, 82 percent in 2008 and 76 percent in 2009). The 2010 hit rate fell to 28 percent, due to the number of
aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in Epicenter, the same area of the Mainshock, main shock, caused as the displaced Crust (geology), crust adjusts to the effects of the main shock. Large earthq ...
s following the 2011 Tōhoku earthquake (which occurred near the end of the 2010 fiscal year); before the earthquake, the hit rate was 72 percent. Measurement techniques have since been refined to ignore minor earthquakes, and the hit rate for FY2011 increased to 56 percent. The JMA intended to increase the hit rate to over 85 percent by FY2015.


Inaccuracies

Although EEW (Earthquake Early Warning) accuracy has been increasing, the following erroneous alarms have been issued: *March 11, 2011 – Warnings were issued that were too severe since multiple separate aftershocks were read as a single quake. In addition, severity was underestimated, causing failure to issue warnings in the Kanto region. *August 8, 2013 – Although an emergency earthquake bulletin was announced at 16:56 JST from Kanto to Kyushu, no shaking was observed. Noise from the ocean-floor seismograph off southeastern
Mie Prefecture is a Prefectures of Japan, prefecture of Japan located in the Kansai region of Honshu. Mie Prefecture has a population of 1,781,948 () and has a geographic area of . Mie Prefecture is bordered by Gifu Prefecture to the north, Shiga Prefecture an ...
was recorded at the same time as shaking from a magnitude 2.3 earthquake in northern
Wakayama Prefecture is a prefecture of Japan located in the Kansai region of Honshu. Wakayama Prefecture has a population of 876,030 () and a geographic area of . Wakayama Prefecture borders Osaka Prefecture to the north, and Mie Prefecture and Nara Prefecture to ...
. *January 5, 2018 – An 11:02 JST earthquake warning for the
Kantō region The is a geography, geographical region of Honshu, the largest island of Japan. In a common definition, the region includes the Greater Tokyo Area and encompasses seven prefectures of Japan, prefectures: Chiba Prefecture, Chiba, Gunma Prefe ...
and
Fukushima Prefecture is a Prefectures of Japan, prefecture of Japan located in the Tōhoku region of Honshu. Fukushima Prefecture has a population of 1,771,100 () and has a geographic area of . Fukushima Prefecture borders Miyagi Prefecture and Yamagata Prefecture ...
was an overestimation, caused by assessing concurrent earthquakes in
Toyama Prefecture is a prefecture of Japan located in the Chūbu region of Honshu. Toyama Prefecture has a population of 993,848 (1 January 2025) and has a geographic area of 4,247.61 km2 (1,640.01 sq mi). Toyama Prefecture borders Ishikawa Prefecture to the ...
(magnitude 3.9) and
Ibaraki Prefecture is a Prefectures of Japan, prefecture of Japan located in the Kantō region of Honshu. Ibaraki Prefecture has a population of 2,828,086 (1 July 2023) and has a geographic area of . Ibaraki Prefecture borders Fukushima Prefecture to the north, ...
(magnitude 4.4) as a single quake. *July 30, 2020 – The epicenter of a 5.8 magnitude earthquake south of Japan was miscalculated, causing the EEW to overestimate the size of the earthquake to be at a magnitude of 7.3, as well as erroneously placing the epicenter to much closer to Japan's main island, Honshū, than it actually was. There were no reports of any significant tremors. *July 28, 2022 – At 16:05 JST an earthquake warning was issued for the area between the Kanto and Kyushu regions (with
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 ...
5-), but no shaking was observed. The warning was quickly cancelled afterwards. It might have been caused by the noise of
lightning strike A lightning strike or lightning bolt is a lightning event in which an electric discharge takes place between the atmosphere and the ground. Most originate in a cumulonimbus cloud and terminate on the ground, called cloud-to-ground (CG) lightning ...
s.


Improvements

Technical improvements are being made to increase the hit rate, including the Integrated Particle Filter (IPF) and Propagation of Local Undamped Motion (PLUM) methods. The IPF method, introduced on 14 December 2016, obtains seismic source elements with a
particle filter Particle filters, also known as sequential Monte Carlo methods, are a set of Monte Carlo algorithms used to find approximate solutions for filtering problems for nonlinear state-space systems, such as signal processing and Bayesian statistical ...
. The PLUM method, introduced on 22 March 2018, predicts the seismic intensity directly from observed intensity without estimating the
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 ...
and scale. Accurate seismic-intensity forecasts can be made for large earthquakes or those whose hypocenter is unknown.


Broadcast format


Television

On
NHK , also known by its Romanization of Japanese, romanized initialism NHK, is a Japanese public broadcasting, public broadcaster. It is a statutory corporation funded by viewers' payments of a television licence, television license fee. NHK ope ...
television channels and other Japanese TV broadcasters (
ISDB Integrated Services Digital Broadcasting (ISDB; Japanese: , ''Tōgō dejitaru hōsō sābisu'') is a Japanese broadcasting standard for digital television (DTV) and digital radio. ISDB supersedes both the NTSC-J analog television system and ...
, including 1seg), an alert is a message window on the screen with the earthquake epicenter (shown as a red X with a white outline) and areas affected by strong tremors. Two sets of chimes sound, followed by a voice announcement in Japanese: In addition to NHK, the announcement is used by
Fuji TV JOCX-DTV (channel 8), branded as or , is a Japanese television station that serves the Kantō region as the flagship (broadcasting), flagship station of the Fuji News Network (FNN) and the Fuji Network System (FNS). The station is owned-and- ...
,
TV Asahi JOEX-DTV (channel 5), branded as , and better known as , is a Japanese television station serving the Kanto region as the flagship station of the All-Nippon News Network. It is owned-and-operated by the a subsidiary of , itself controlled by ...
and
Tokyo MX JOMX-DTV (channel 9), branded as Tokyo MX (officially stylized as TOKYO MX), is an independent station, independent television station in Tokyo, Japan, owned by the . It is the only television station that exclusively serves the city and parts ...
.
Nippon TV JOAX-DTV (channel 4), branded as (NTV) or Nippon TV, is a Japanese television station serving the Kantō region as the flagship station of the Nippon News Network and the Nippon Television Network System, owned and operated by the , a sub ...
and TBS shorten it to ''"Kinkyū Jishin Sokuhō desu"'' ("This is an Earthquake Early Warning").
TV Tokyo JOTX-DTV (channel 7), branded as is a Japanese television station that serves as the flagship of the TX Network.landslide 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. Landslides ...
s or a
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, ...
caused by the quake in the affected area. If tsunami warnings are issued, the system utilizes 1seg to automatically turn on (and tune to NHK) all radios and televisions with 1seg technology in at-risk areas. In addition to Japanese, the warnings are broadcast in English, Mandarin, Vietnamese, Korean and Portuguese.


Mobile-phone networks

Japan's three major mobile phone carriers—NTT docomo, au ( KDDI and Okinawa Cellular) and
SoftBank is a Japanese multinational Investment company, investment holding company headquartered in Minato, Tokyo, that focuses on investment management. The group primarily invests in companies operating in technology that offer goods and services ...
Mobile—have developed Cell Broadcast systems to send multiple users an SMS of the EEW. It is mandatory for 3G cell phones sold after 2007 to receive this service, although foreign manufacturers such as Nokia, Apple, HTC, LG and Samsung are exempt. In August 2011, Apple announced that its iOS 5 iPhone platform would support EEW notification.


Other


NTT Docomo Inc.

EEW is enabled by default on all models of the released after 26 November 2007, and on some FOMA high-speed models in the released after February 2008.


au

The system was enabled on all models in early 2008, including W61CA, W61H, W61K, W61SA, W61SH, W62SA and a few
smartphone A smartphone is a mobile phone with advanced computing capabilities. It typically has a touchscreen interface, allowing users to access a wide range of applications and services, such as web browsing, email, and social media, as well as multi ...
models, such as IS02 (TSI01). KDDI and Okinawa Cellular began free EEW broadcasts via au's SMS, , on 25 March 2008.


SoftBank Mobile

On 30 May 2007, SoftBank announced development of an EEW broadcast system similar to NTT docomo's and au's. Deployment of the system was originally planned for FY2008, but was postponed for two years. On 25 August 2010, EEW service began on
Shikoku is the smallest of the List of islands of Japan#Main islands, four main islands of Japan. It is long and between at its widest. It has a population of 3.8 million, the least populated of Japan's four main islands. It is south of Honshu ...
, in the
Kansai The or the lies in the southern-central region of Japan's main island Honshū. The region includes the prefectures of Nara, Wakayama, Kyoto, Osaka, Hyōgo and Shiga, often also Mie, sometimes Fukui, Tokushima and Tottori. The metropoli ...
, Tōkai, Tōhoku (seven prefectures) and
Chūgoku region The , also known as the region, is the westernmost region of Honshū, the largest island of Japan. It consists of the prefectures of Hiroshima, Okayama, Shimane, Tottori and Yamaguchi. As of the 2020 census, it has a population of 7,328,339 ...
s, and portions of the
Kantō region The is a geography, geographical region of Honshu, the largest island of Japan. In a common definition, the region includes the Greater Tokyo Area and encompasses seven prefectures of Japan, prefectures: Chiba Prefecture, Chiba, Gunma Prefe ...
. The EEW broadcast network has covered the whole country since 7 December 2010. The SoftBank 831N was the only model supporting EEW in March 2011, although more models had been expected to support the system after summer 2010.


Other

RC Solution Company developed Yurekuru Call for iPhone, a free
iPhone The iPhone is a line of smartphones developed and marketed by Apple that run iOS, the company's own mobile operating system. The first-generation iPhone was announced by then–Apple CEO and co-founder Steve Jobs on January 9, 2007, at ...
application to receive EEW which is distributed on the Apple
App Store An app store, also called an app marketplace or app catalog, is a type of digital distribution platform for computer software called applications, often in a mobile context. Apps provide a specific set of functions which, by definition, do not i ...
; the application is also available for Android. Notification of an EEW might be delayed or blocked if communication lines are congested. The Japanese version of iOS 5 for iPhone has built-in EEW functionality.


Radio

A specific, common chime tone from FM stations is automatically detected and turns on the radio (if in
sleep mode Sleep mode (or suspend to RAM) is a low power mode for electronic devices such as computers, televisions, and remote controlled devices. These modes save significantly on electrical consumption compared to leaving a device fully on and, upon resu ...
), sounding a loud chime and broadcasting an EEW message before the quake begins by detecting S-waves. When the S-wave has been analyzed, detailed information on the earthquake (such as seismic scale and areas under threat) is announced. The following radios receive EEWs from radio stations and are free of information or connection fees: * Iris Ohyama EQA-001 supports this subject the *Iris Ohyama EQA-101 supports this subject the * Uniden EWR200 supports EEW and the * recognizes
NHK Radio 1 , known by its callsign NHK AM, is Japan's oldest radio station operated by the public broadcaster, NHK. Its programming output, which consists of news, current affairs, and information is broadly similar to the BBC's Radio 4 in the United Kingd ...
announcers. EEW broadcasts can be received in areas without
broadband Internet access In telecommunications, broadband or high speed is the wide- bandwidth data transmission that exploits signals at a wide spread of frequencies or several different simultaneous frequencies, and is used in fast Internet access. The transmission m ...
. Signal quality, speed and service area may vary from station to station.


Stations

*
NHK Radio 1 , known by its callsign NHK AM, is Japan's oldest radio station operated by the public broadcaster, NHK. Its programming output, which consists of news, current affairs, and information is broadly similar to the BBC's Radio 4 in the United Kingd ...
and Radio 2, nationwide * JOGV-FM (bayfm78), Chiba * JOAU-FM (Tokyo FM),
Tokyo Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...
* JOAV-FM (J-Wave),
Tokyo Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...


Cable television

Japanese cable TV stations offer EEWs. (JCN) rents a receiver which notifies the user of the estimated Shindo scale and the time remaining (0 to 5 seconds). Some cable-TV stations also broadcast EEWs on FM
community radio Community radio is a radio service offering a third model of radio broadcasting in addition to commercial broadcasting, commercial and public broadcasting. Community broadcasting, Community stations serve geographic communities and communities o ...
stations and provide free equipment to prefecture and municipal facilities.


Internet

, a weather-information company, began a paid EEW service ( The Last 10 Seconds) on October 15, 2007. The service requires a computer running
Windows 2000 Windows 2000 is a major release of the Windows NT operating system developed by Microsoft, targeting the server and business markets. It is the direct successor to Windows NT 4.0, and was Software release life cycle#Release to manufacturing (RT ...
or later with an always-on connection to the Internet. The EEW application can be configured to receive information on earthquakes with a JMA magnitude of 3.5 or higher or with a seismic intensity of 3 or higher. Newer versions of the program allow for the announcement of lower-intensity earthquakes. The program announces the approximate location of the epicenter, the expected JMA seismic intensity and displays a countdown to expected major shaking. , a disaster-prevention technology company which is part of the
Railway Technical Research Institute , or , is the technical research company under the Japan Railways group of companies. Overview RTRI was established in its current form in 1986 just before Japanese National Railways (JNR) was privatised and split into separate JR group compan ...
Group, released an application (EQMessenger) to receive ANET Alert on 7 July 2008. This deciphers and broadcasts EEW information on the epicenter, the estimated seismic intensity at the user's location, and the time remaining before the arrival of the S-wave. When the estimated seismic intensity exceeds the preset level, EQMessenger can sound a warning and display the epicenter, intensity estimation and the arrival of the tremor on a pop-up map. A similar, free Windows program, SignalNow Express, was made available by the Strategy Corporation ( ストラテジー株式会社) after the 2011 Tōhoku earthquake. A free multi-platform program, that works on Windows, Mac, and Linux
JQuake
was released on February 14, 2020 as an inspiration to another program called Kiwi Monitor. JQuake tracks information in real-time, and reports any tsunami events that occur. A scratch-based program available on the web provides detailed earthquake and tsunami information quickly.


Design

The Earthquake Early Warning logo used by the Japan Meteorological Agency is a . Many earthquake-preparedness activities in Japan use the catfish as a mascot; in Japanese mythology earthquakes were caused by a giant catfish, or seeing catfish foretold an earthquake.


See also

*
Earthquake warning system 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 ...
*
Earthquake prediction Earthquake prediction is a branch of the science of geophysics, primarily seismology, concerned with the specification of the time, location, and magnitude of future earthquakes within stated limits, and particularly "the determination of par ...
* Emergency Warning Broadcast system *
J-Alert J-Alert (; full name ) is the early warning system used in Japan. J-Alert was launched in February 2007. The system is designed to quickly inform the public of threats and emergencies such as earthquakes, severe weather, and other dangers. The s ...
* Cell Broadcast *
Specific Area Message Encoding Specific Area Message Encoding (SAME) is a Communications protocol, protocol used for framing and classification of broadcasting Emergency population warning, emergency warning messages. It was developed by the United States National Weather Serv ...
*
Weather radio A weather radio is a specialized radio receiver that is designed to receive a public broadcast service, typically from government-owned radio stations, dedicated to broadcasting weather forecasts and reports on a continual basis, with the routine w ...
*
ShakeAlert ShakeAlert is an earthquake early warning system (EEW) in the United States, developed and operated by the United States Geological Survey (USGS) and its partners. As of 2021, the system issues alerts for the country's West Coast (specifically ...


References


External links

*
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 ...

Earthquake Early Warnings




* ttp://www.bousai.go.jp/jishin/eew/eew_top.html Ministerial Meetings on EEW Public Relations
Cabinet Office (Japan) The (CAO) is an agency of the Cabinet of Japan. It is responsible for handling the day-to-day affairs of the Cabinet. The Cabinet Office is formally headed by the Prime Minister of Japan, Prime Minister. Ministers History The Cabinet Of ...

Earthquake Early Warning Users Association

Italian and Japanese Seismic Early Warning System by applying Data Mining Techniques


Real-time Earthquake Information Consortium

(NIED) ** ttp://www.bosai.go.jp/kenkyu/sokuji/index.htm Research Project for the Practical Use of Real-time Earthquake Information Networks
High Sensitivity Seismograph Network Japan (Hi-net)
{{in lang, ja
Seconds Before the Big One: Progress in Earthquake Alarms
cientific American, 11 March 2011
Brazil adopts Japanese TV warning system
Advanced Television Ltd. 13 Jun 2011
The USGS and Partners Work to Develop an Earthquake Early Warning System for California
United States Geological Survey The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on Mar ...
17 April 2012 Earthquake early warning systems Earthquakes in Japan Emergency management in Japan Information systems Japan Meteorological Agency Public safety