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The Earthquake Early Warning (EEW) (緊急地震速報, Kinkyū Jishin Sokuhō) is a warning issued when an earthquake in Japan is detected. The warnings are issued mainly by the Japan Meteorological Agency (JMA), along with guidance on how to react to the warnings.
Contents
Introduction
The JMA has two Earthquake Early Warning schemes. One is for the National Meteorological and Hydrological Services and the other is for the general public. When there is a P-wave detection from any two or more of the 4,235 seismometers installed throughout Japan, the JMA automatically analyzes and predicts the rough area of the earthquake's epicenter. These rough predictions allow the JMA to warn people in affected prefectures through TV and radio if strong shaking is expected.
An Earthquake Early Warning alert (緊急地震速報(警報)) is issued to the general public when an earthquake of Japan seismic scale "5-lower" or higher is expected. An Earthquake Early Warning forecast (緊急地震速報(予報)) is issued to the National Meteorological and Hydrological Services when an earthquake of Japan seismic scale 3 or higher, or magnitude 3.5 or more is expected, or when a measurement of more than a 100 gals is detected in the amplitude of P-wave or S-wave.
The Earthquake Early Warning is set up to help people in minimizing damages caused by an earthquake: people may take shelter or move away from dangerous areas such as cliffs. Railway workers use this warning to slow down trains, and factory workers may use it to stop assembly lines before the shaking reaches them.
The effectiveness of a warning depends on the position of the receiver. After receiving a warning, a person may have few seconds to a minute or more to take action. Areas near the epicenter may experience strong tremors before any warning.
After the 2011 Tōhoku earthquake and tsunami, the early warning system, along with Japan's tsunami warning system, was considered to be effective. Although the tsunami killed over 10,000 people, many more people would have lost their lives without the early warning system.
In April 2011, the Chilean Subsecretary of Telecommunications disclosed that they also hope to establish a similar earthquake early warning system.
Hit rate
The JMA announced the hit rate of the Earthquake Early Warning for the 2011 fiscal year on 31 May 2012. The hit rate is defined as the percentage occurrence of the warning issued immediately upon P-waves detected having a Japan Meteorological Agency seismic intensity scale (震度, shindo) number (range 0 to 7) that falls within plus-minus 1 Magnitude-Shindo Number of ten Magnitude-Shindo Numbers measured for that earthquake.
For the fiscal years 2007 to 2009 the hit rate was over 75%. In fiscal year 2010 the hit rate came down to 28% due to the number of aftershocks following the 2011 Tōhoku earthquake and tsunami, which occurred near the end of fiscal year 2010. The hit rate for that year had been 72% until the Tohoku earthquake. Measurement techniques have subsequently been refined to ignore small scale earthquakes; the hit rate for fiscal year 2011 increased to 56%. The JMA aimed to increase the hit rate to over 85% in fiscal year 2015.
Television
On NHK television channels and other Japanese TV broadcasters (ISDB including 1seg), has an alert that consists of a message window that flashes on the screen showing the earthquake epicenter and the areas affected by strong tremors. At the same time, two sets of chimes sound, after which a voice announces in Japanese:
The announcement above is used by the NHK and Tokyo MX, whilst Nippon TV and TBS simply shorten it to "Kinkyū Jishin Sokuhō desu". Fuji TV and TV Asahi both sound a set of chimes, but do not use a voice announcement.
These alerts also inform viewers whether or not there is a risk of a landslide or tsunami 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 the areas at risk. All warnings are broadcast in five languages: English, Mandarin, Korean and Portuguese, as well as Japanese.
Mobile phone networks
Japan's three major mobile phone carriers, NTT docomo, au (KDDI and Okinawa Cellular) and SoftBank Mobile, have developed simultaneous broadcast systems to allow multiple users to receive an SMS telling of the EEW ('Cell Broadcast').
It is now mandatory for 3G cellular phones that were put on the market after 2007 are to be able receive this service, though overseas manufacturers (Nokia, Apple, HTC, LG, Samsung, etc.) are not covered. In August 2011, Apple announced that its iOS 5 iPhone platform will support early warning notification.
NTT docomo
EEW is enabled by default on all models of the FOMA 905i series (FOMA 905iシリーズ) released on 26 November 2007, some FOMA High-Speed models of the FOMA 705i series (FOMA 705iシリーズ) released in February 2008.
au
EEW is enabled on all models from early 2008, including W61CA, W61H, W61K, W61SA, W61SH, W62SA and a few smartphone models, such as IS02 (TSI01). KDDI and Okinawa Cellular started EEW broadcast via au's Short Message Service called C-mail (ja:Cメール) for free on 25 March 2008.
SoftBank Mobile
On 30 May 2007, SoftBank announced development of an EEW broadcast system similar to those of NTT docomo and au. Deployment of this system was originally planned in the fiscal year 2008 but postponed for two years. On 25 August 2010, EEW service started in all areas of the Kansai region, Tokai region, Tohoku region (seven prefectures), Chugoku region, and Shikoku region as well as limited areas of the Kanto region. The EEW broadcast network covers the whole country since 7 December 2010. As of March 2011, ja:SoftBank 831N is the only model that supports EEW, although more models are expected to support EEW after summer 2010.
Other
RC Solution Co. developed an iPhone application named "Yurekuru Call for iPhone" to receive EEW, which is distributed on the Apple App Store for free; the application is now also available for Android. Notification of an EEW might be delayed or blocked if communication lines are congested. The Japan-localized version of iOS 5 for iPhone has built-in EEW functionality.
Radio receivers
The specific and common chime tone from FM stations is automatically detected internally and turns on the radio (if in sleep mode) and loudly sounds a chime tone and EEW message before shaking occurs by S-wave. Once the S-wave has been analyzed, detailed information on the earthquake, such as its seismic scale and the areas under threat, is announced.
These receivers utilize EEW broadcast from radio stations and are free of specific information fees or connection fees. EEW radio waves can be received even in areas where no broadband Internet access is available. The quality of service, rapidity, and service area may vary from station to station.
Radio Stations with the EEW System
Cable television
Japanese cable TV stations offer affordable EEW services. For example, Japan Cablenet (ja:ジャパンケーブルネット) (JCN) rents out a receiver that receives EEW for advanced users and notifies the user of the estimated Shindo scale and the remaining time (0 to 5 seconds). Some cable TV stations also broadcast EEW on community radio FM and provide equipment to prefectural and municipal facilities for free.
Internet
Weathernews Inc. (ja:ウェザーニューズ), a weather information company, started a paid service to broadcast EEW for advanced users, The Last 10-Second, used by people and businesses on 15 October 2007. This service requires a computer running Windows 2000 or later with an always-on connection to the Internet and offers an affordable alternative to a costly communication terminal used exclusively for EEW. The EEW application installed on the computer can be configured to receive information on all 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. When an EEW warning is issued, the program will announce the approximate location of the epicenter, the expected JMA seismic intensity and display a countdown of when major shaking is to be expected.
On 7 July 2008, ANET Co., Ltd. (ja:ANET, アネット), a disaster prevention technology company of the Railway Technical Research Institute Group, released an application, EQMessenger, to receive ANET Alert, which ciphers and broadcasts EEW information on the epicenter, the estimated seismic intensity at the user's location, and the remaining time 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, the intensity estimation point, and the arrival of the tremor on a pop-up map.
After the 2011 Tōhoku earthquake, a similar Windows program was made available for free by the Strategy Corporation (ja:ストラテジー株式会社) called SignalNow Express.
Identification of EEW capable devices
The current Earthquake Early Warning logo used by the Japan Meteorological Agency uses a yellow catfish known as a Namazu (鯰). Many earthquake preparedness activities in Japan use the catfish as a mascot, as Japanese lore suggested that earthquakes were caused by a giant catfish making tremors, or that the sight of catfish foretold of earthquakes.