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Earthquake Early Warning (EEW), or 緊急地震速報 (きんきゅうじしんそくほう)''' in Japanese, is an earthquake early warning system designed to issue alerts several seconds to several tens of seconds before a large earthquake tremor reaches an area. It is provided by the Japan Meteorological Agency as a forecast and warning.

The system began partial trial operations in 2004 and full operations targeting almost all residents of Japan, except for some remote islands, began on October 1, 2007.

There are two types of warnings issued: "for the general public" (seismic intensity warning, special seismic intensity warning) which is announced when the expected seismic intensity is weak 5 or higher, and conveys "the areas where strong tremors of seismic intensity 4 or stronger will occur," and "for advanced users" (seismic motion forecast) which has a high speed of response but has lower accuracy for the first report with a lower announcement criterion, and can provide various information such as "the reach time of earthquake waves and tremors in each area."

Overview
An earthquake early warning system (EEW) is designed to issue alerts a few seconds to tens of seconds before strong shaking arrives, using data from seismic sensors located close to the epicenter to estimate the earthquake's magnitude and location. This information is used to predict the arrival time and intensity of the earthquake's main motion in different areas and disseminate this information as quickly as possible.

The system is expected to help mitigate earthquake disasters if the short amount of time before the arrival of the main motion can be utilized effectively. For example, in the case of a subduction earthquake or a deep slab earthquake occurring far from land, there may be a few seconds to tens of seconds of lead time. However, due to technical limitations, there may be instances where the system cannot issue an alert before the arrival of the main motion, particularly for shallow earthquakes that originate near land. Efforts to improve the system include increasing the number of observation points and speeding up data processing and communication.

There is also a risk of false alarms, and concerns have been raised about potential confusion and chaos that may arise in society in response to the alerts. Therefore, the system has been introduced gradually, starting with limited and experimental alerts in 2004, and the "general public" alerts were launched on October 1, 2007, after careful consideration of public relations strategies. The alerts have been expanded to a wider audience, including mobile phones, with various devices and software provided by different companies to offer "advanced user" alerts.

It should be noted that the decision to implement the system is left to the discretion of individuals and organizations, and there are no plans to make it mandatory.

Difference between the two types of Earthquake Early Warning

Linkage with information on long-period seismic motion
Long-period seismic motion that causes significant damage to tall buildings and the like was not initially linked to emergency earthquake alerts and warnings. However, as the magnitude of this motion cannot be adequately expressed by seismic intensity, linkage between long-period seismic motion and emergency earthquake alerts and warnings has been considered. From February 1, 2023, operation has started to include long-period seismic motion class as a subject of announcement.

Legal positioning
The earthquake early warning system is classified as a forecast, warning, or special warning for seismic motion, and like other forecasts (watch), warnings, and special warnings, it is mandatory under the Meteorological Service Act Article 13 for the Japan Meteorological Agency (JMA) to issue. A seismic motion special warning was newly established by the implementation of a special warning on August 30, 2013.

Classification of seismic motion forecasts, warnings, and special warnings (according to JMA materials)


 * Seismic motion special warning: Issued when the maximum predicted seismic intensity is weak 6 or above or the maximum predicted long-period seismic motion class is 4. A warning is issued to areas where strong shaking is expected, indicating a significant and serious disaster may occur due to the seismic motion.
 * Seismic motion warning: Issued when the maximum predicted seismic intensity is weak 5 or above, or the maximum predicted long-period seismic motion class is 3 or above. A warning is issued to areas where strong shaking is expected, indicating that a serious disaster may occur due to the seismic motion.
 * Seismic motion forecast: Issued when the maximum predicted seismic intensity is 3 or above, the maximum predicted long-period seismic motion class is 1 or above, or the estimated magnitude is 3.5 or above.

However, due to the current technological limitations in terms of promptness, at the time of issuing the earthquake early warning, there is no distinction made between warning and special warning.

In consideration of the differences in the degree of severity, when the JMA issues an earthquake early warning to the "general public," it is announced under the name "Earthquake Early Warning (Warning)" or simply "Earthquake Early Warning." Seismic motion forecasts are issued to "advanced users" under the name "Earthquake Early Warning (Forecast)."

Individuals other than the JMA are generally not permitted to issue warnings (including special warnings) for seismic motion (Article 23 of the same law), and a permit from the JMA chief is required to perform forecast duties (Article 17). The same law stipulates that the JMA should make users aware of the distinction between its "warning" and the "forecast" issued by authorized businesses.

Regarding "warnings," similar to weather warnings, the JMA is required to "immediately notify the National Police Agency, the Ministry of Land, Infrastructure, Transport and Tourism, the Japan Coast Guard, prefectures, Nippon Telegraph and Telephone Corporation, and Japan Broadcasting Corporation of the content of that warning matter in accordance with the provisions of the Cabinet Order" (Article 15). If it falls under the "special warning" category, there is no difference in the expression of "warning" at the time of announcement, and unlike other special warnings, there is no difference in the handling of notification recipients between "warning" and "special warning."

From this point onwards, this entry describes "warnings" and "special warnings" without distinguishing between them.

Chronology of the system

 * February 25, 2004: The trial operation of the "Emergency Earthquake Warning" begins for administrative agencies, transportation, media, communication, and other organizations that wish to participate. The target area is from the east coast of Kyushu to Kanto, integrating the "Nowcast Earthquake Information" and "Real-time Earthquake Information" under development.
 * March 30, 2005: The target area of the trial operation is expanded to the Pacific coast from Tohoku to Hokkaido.
 * June 8, 2005: The earthquake meters of the National Research Institute for Earth Science and Disaster Resilience are added to the data provider for the trial operation, and the target area is expanded to almost all of Japan.
 * August 1, 2006: The early provision of the system begins for companies that wish to participate.
 * October 1, 2007: "General-purpose" alerts are introduced from 9:00 a.m. (JST) on this day. The alerts that had been provided earlier are distinguished as "for advanced users." Alerts are also introduced on television broadcasts and some public facilities.
 * December 1, 2007: In the amendment of the Meteorological Service Act, which came into effect on this day, the emergency earthquake warning was classified as a forecast and an alert.
 * August 30, 2013: In the amendment of the Meteorological Service Act, which came into effect on this day, the emergency earthquake warning with a predicted seismic intensity of weak 6 or higher is classified as a special alert.

Technology chronology

 * 1996: Following the Hyogo-ken Nanbu earthquake, the construction of a highly sensitive seismic observation network (Hi-net) was decided. Later, the installation of highly sensitive seismometers, which became essential for urgent earthquake alerts, began (as of 2011, installed at over 800 locations). Meanwhile, the application of communication technology, which utilizes the analysis of past earthquake waveforms by digital seismometers and the advancement of high-speed, large-capacity technology, began to be considered for the provision of earthquake information in real-time.
 * April 2003: The Ministry of Education, Culture, Sports, Science, and Technology, the Japan Meteorological Agency, and the National Research Institute for Earth Science and Disaster Resilience (NIED) jointly launched the Leading Project "Practical use of Advanced and Immediate Earthquake Information Transmission Network," with the aim of making real-time earthquake information transmission practically possible. By the end of the 2007 fiscal year, the project aimed to integrate NIED's "real-time earthquake information" and the Japan Meteorological Agency/Railway Technical Research Institute's "Nowcast earthquake information" to develop rapid, high-level earthquake information transmission methods.
 * December 2004: The displacement amplitude calculation filter was modified.
 * October 2005: The magnitude estimation formula was switched.
 * April 4, 2006: Improvements were made to the processing that did not determine the epicenter for estimated hypocentral distances of 200 kilometers or more by single-point processing.
 * September 2006: Measures were implemented not to announce seismic intensity for earthquakes estimated to be deeper than 150 kilometers, where it is difficult to predict seismic intensity.
 * August 3, 2009: From noon, five cable-type seafloor seismometers off the coast of southeastern Nankai and two seismometers in island regions were put into use. Additionally, the calculation formula, which tended to underestimate the magnitude of earthquakes, was improved (described later).


 * Fiscal years 2009-2010: Lightning protection was implemented by installing lightning-resistant transformers that perform A/D conversion in the sensor unit.
 * Year 2011:


 * March 1, 2011: Ten multifunctional seismometers were installed and put into use in the southwest islands (eight points), Izu Islands (one point), and Oita Prefecture (one point).
 * August 11, 2011: Following the occurrence of many false reports after the March 11, 2011 earthquake off the Pacific coast of Tohoku (the Great East Japan Earthquake), a modification program to distinguish earthquakes that occurred simultaneously and exclude weak earthquakes from calculations was put into operation.


 * October 2, 2012: Amplification was introduced for each observation point to improve seismic intensity prediction accuracy.
 * Fiscal years 2011-2012: A satellite line for emergency power supply and backup that operates for about 72 hours was installed to implement measures to cope with observation point shortages.
 * February 13, 2013: A new calculation formula was applied to improve magnitude estimation accuracy.
 * On March 31, 2015, two points of the DONET (Dense Oceanfloor Network System for Earthquakes and Tsunamis) in the offshore southeast region of the Kii Peninsula and 15 points of the KiK-net (Kiban Kyoshin network) were put into operation. This allowed the time until earthquake warnings to be shortened by a few seconds for earthquakes occurring along the Nankai Trough or directly beneath the Tokyo metropolitan area.
 * On December 14, 2016, the IPF (Improved P-wave Fast determination) method was introduced, which is more accurate at identifying multiple earthquakes than previous methods. In addition, measures were introduced to exclude seismic amplitude values that are geologically impossible and to set upper limits on the magnitude that can be considered from data at a single observation point.
 * On March 22, 2017, it was reported that long-period seismic motion should be added to the announcement criteria for emergency earthquake alerts during the Meteorological Agency's Emergency Earthquake Alert Evaluation and Improvement Study.
 * On March 22, 2018, the combined use of the PLUM (Probabilistic Seismic Intensity Mapping) method and the conventional method was introduced for emergency earthquake alerts. The PLUM method predicts seismic intensity from the strength of shaking observed by seismic instruments near the prediction point, without estimating the epicenter. This method enables the issuance of highly accurate emergency earthquake alerts even for huge earthquakes with wide-ranging epicenters. The predicted seismic intensity is announced based on the larger value between the PLUM and conventional methods. A function was also introduced to evaluate whether the estimated epicenter and magnitude from the conventional method are reasonable by comparing them to actual shaking to prevent overestimation of seismic intensity. Furthermore, from the day of the PLUM method's introduction, predicted seismic intensities are no longer listed in telegrams for data processed from a single observation point.
 * On June 27, 2019, the whole system of DONET1 and DONET2, which had already been partly utilized for emergency earthquake alerts, and the seismic and tsunami observation system (S-net) in the Japan Sea Trench to the west of the Japan Trench were put into operation. This allowed the time until earthquake warnings to be shortened by up to 25 seconds for earthquakes occurring in the Japan Sea Trench and up to 10 seconds for earthquakes occurring off the Kii Peninsula and off Cape Muroto.
 * 2020:
 * March 24th: The full utilization of S-net, including the eastern part of the Japan Trench, began in the afternoon of the same day. As a result, the time until the announcement of earthquakes occurring east of the Japan Trench can be shortened by up to 10 seconds, and up to 30 seconds compared to before the use of S-net's observation data.
 * September 7th: In response to a false report of an emergency earthquake warning for the earthquake that occurred near Torishima on July 30th of the same year (described later), an urgent improvement measure was implemented from 11:00 on the same day, which does not use observation data from points more than 700 kilometers away from the epicenter to prevent overestimation of magnitude using distant observation data.


 * 2023:
 * February 1st: Long-period seismic motion was added as a target of emergency earthquake warnings.

Background of development
In the Emergency Earthquake Warning (EEW) system, seismic waves are monitored by an observation network, and estimation of earthquakes begins at the stage where only P waves have been detected. When a certain magnitude earthquake is estimated, an alarm is issued. In the history of technology, the first technology that detected S waves and was linked to alarm issuance and machine control was put into practical use on Japan's Tokaido Shinkansen line in the 1960s. The technology to issue an alarm at the P wave stage was put into practical use in 1992 on the Tokaido Shinkansen Yurikamome line after test operations on the Shinkansen in the 1980s.

In Japan, the system was mainly used in the field of railway safety and was not announced to the general public. However, the Great Hanshin-Awaji earthquake in 1995 became a major opportunity to increase public interest in earthquake warning systems for the general public. The first earthquake warning system for the general public was developed in 1993 in Mexico City, known as SAS. Following this, the Emergency Earthquake Warning system was developed in Japan, which became the world's first system to notify the public covering almost the entire country.

Data used
The information on earthquake motion used in the system comes from about 690 seismographs and seismic intensity meters operated by the Japan Meteorological Agency as of March 24, 2020, as well as data from about 1,000 observation points of the National Research Institute for Earth Science and Disaster Resilience, including the High-sensitivity Seismograph Network (Hi-net) and the KiK-net strong-motion seismograph network established since 1996. Since 2011, in order to shorten the time until the issuance of preliminary reports, data from the Earthquake and Tsunami Observation System (DONET and DONET2) established on the seafloor along the Nankai Trough and the Japan Trench Seafloor Earthquake and Tsunami Observation Network (S-net) laid out along the Japan Trench from the Boso Peninsula to off Nemuro are being utilized sequentially.

Calculation of occurrence time and epicenter location
This method involves improving the Omori formula for epicentral distance using techniques such as the Territory method and Grid Search method, along with corrections based on known seismic wave velocity distributions. This technique was established in the early 20th century. Seismic waveforms are observed continuously at several hundred locations in Japan. These data are processed using techniques such as digital waveform bandpass filtering, level detection, B-Δ method for noise discrimination and epicentral distance calculation. When significant vibrations are detected, the data are sent to a data center for analysis. If data from multiple observation points indicate that an earthquake is likely to have occurred rather than being noise, the Territory method or Grid Search method is used to calculate the occurrence time and epicenter location, and the magnitude is estimated.

Magnitude and seismic intensity calculation
The method used for magnitude calculation applies the "P-wave magnitude (P-wave M)" based on the maximum amplitude between the P-wave arrival and the S-wave arrival in the initial stage, and then switches to the "moment magnitude (Mw)" obtained from the maximum displacement amplitude of the entire waveform at an appropriate time. Based on these seismic source parameters, the maximum seismic intensity is predicted from the surface maximum velocity (PGV) at each point calculated by adding the correction for the known ground motion amplification factor of the ground at the seismic distance using statistical (empirical) methods. The arrival time of the major motion is also predicted from the theoretical travel time of the S-wave. Rapid announcements are made for earthquakes that meet the criteria described below, but various processing is added in the actual system to improve accuracy and prevent false detections.

Information Transmission
The earthquake early warning system requires information to be transmitted in a matter of seconds, and efforts are made to minimize the delay caused by processing and transmission in order to maximize the amount of time available to warn people before the main shock of an earthquake reaches their location. Various measures are taken to improve the speed of the delivery system and network.

Information delivered to mobile phones and other devices is presented in an easily understandable format, such as video or audio, but there are various forms of delivery. Specialized devices are set up in advance to provide location information and ground conditions, and when an earthquake is detected, an alarm may sound, and information about the earthquake's occurrence and intensity may be conveyed via audio, text, images, or flashing lights. In large facilities, alarms and audio broadcasts may be used to alert everyone inside.

Examples of Specific Response Measures
Guidelines have been established by relevant organizations to determine what measures should be taken to increase safety when earthquake early warnings are received through images, text, audio, or other means. Examples of response measures based on these guidelines are listed below.

The most important basic principle is to ensure personal safety without panic, depending on the surrounding conditions.

If the earthquake early warning is received indoors, such as in a home, workplace, or school, it is necessary to immediately open windows and doors to secure evacuation routes before the arrival of the P-wave, or at the pre-P-wave stage if the S-wave has not yet arrived. It is also necessary to move away from falling objects or debris and hide under a table to protect the head, as in the immediate aftermath of the earthquake. (If the shaking is extremely strong, such as a seismic intensity of 6+ or 7, there is nothing that can be done until the S-wave subsides.)

In crowded places such as commercial facilities or event venues, it is necessary to protect the head as indoors, stay away from falling objects, debris, signs, lighting, and other falling objects, and to avoid rushing to the exits to prevent chaos. If there are instructions from personnel such as security guards, follow them promptly (personnel should immediately start opening doors).

Outdoors, it is necessary to stay away from falling objects such as falling debris, signs, lighting, and window glass, and if possible, evacuate to a building with high seismic resistance. In addition, if near cliffs or similar features, it is necessary to stay away from them as there is a risk of landslides or falling rocks. If close to the coast, it is also necessary to evacuate quickly to high ground or the upper floors of a building in preparation for a tsunami.

When driving a car, first warn other drivers by turning on hazard lights or other means, then slow down and pull over to the left side of the road. Avoid sudden stops or sudden steering as there is a risk of rear-end collisions. On buses and trains, it is necessary to hold onto straps or handrails firmly to support the body. When in an elevator, press all buttons to stop at every floor and quickly exit the elevator.

Because calm action is required without panic, it is desirable to conduct training that assumes receipt of early warnings several times in advance. For example, according to guidelines for facility managers, creating manuals that incorporate responses to earthquake early warnings and conducting training based on them is required. Even in facilities that do not have an early warning system, it is recommended to create appropriate manuals and conduct training considering the possibility of receiving early warnings on TV or mobile phones.

Active utilization of earthquake early warning system
Regarding the potential for utilizing the earthquake early warning system, research has been conducted in advance, such as the verification and research of the use of the emergency earthquake early warning system by the Ministry of Education, Culture, Sports, Science and Technology's reading project. Since then, systems for utilizing the emergency earthquake early warning system in various fields have been considered by research institutes and companies. Examples are listed below.

These include train operation control, incorporation of the early warning system into advanced road traffic systems, notifications and guidance to vehicles while driving, signal control and traffic regulation, landing and takeoff regulations at airports, notifications to ships preparing for tsunamis, expediting the closure of tsunami-prepared floodgates, evacuation guidance and instructions in facilities or crowded places, ensuring safety in homes and workplaces, controlling communication lines such as phones, controlling elevators and amusement equipment, controlling operating systems in factories, ensuring safety in high-risk places such as medical and construction sites, and controlling power systems, waterworks, and city gas systems.

In particular, regarding tsunami forecasts, time can be saved by utilizing the predicted values of this emergency earthquake early warning system. In fact, when a tsunami warning was announced for the Noto Peninsula Earthquake in March 2007 and the Niigata Chuetu Offshore Earthquake in July of the same year, time was saved by utilizing the emergency earthquake early warning system. Additionally, in the earthquake that occurred off the coast of Fukushima in July 2008, about one minute was saved. The maximum time that can be saved is about two minutes, and there is also a possibility of announcing a tsunami forecast within about one minute from the occurrence of an earthquake.

Furthermore, the Japan Meteorological Agency recommends that "advanced users" undergo training to calmly judge and take action based on early warning information, as there is a possibility of errors due to the large amount of information provided. Therefore, in places such as facilities and disaster prevention radios where there are many unspecified people, it is recommended to prevent confusion by simply conveying that "strong shaking" may occur within the range of the contents of the "general public" (alarm) announcement for areas where the predicted seismic intensity is 4 or higher.

Overview
With the aim of acquiring and disseminating the handling of emergency earthquake alerts at the time of the quick report announcement through practical experience, the Japan Meteorological Agency sets December 1st of every year as the emergency earthquake alert training day and carries out the training in collaboration with distribution agencies.

In addition, the Japan Meteorological Agency has created "Guidelines for the use of emergency earthquake alerts and a kit for training on response actions when receiving emergency earthquake alerts," which are available to the general public, so that training on response actions when receiving emergency earthquake alerts can be conducted in daily life.

On June 28, 2012, a nationwide training was conducted in which a total of 1,400 organizations, including 256 local governments that operate the nationwide instant warning system (J-ALERT), local governments that broadcast via disaster prevention administrative radio, local governments that conduct broadcasting within their own offices, and other broadcasts (community FM), participated.

Types of Emergency Reports
As mentioned earlier, there are two types of emergency reports. "Advanced user-oriented" reports provide abundant information that can be used to generate greater disaster prevention effects if configured by the user on their own terminal. "General-purpose" reports provide only the minimum information necessary to ensure appropriate action is taken by those who may not be fully aware of the alert.

The contents, usage, and precautions of each utilization system have been considered by the "Leading Project" and various industry associations.

"Advanced User" Emergency Earthquake Alert
The "Advanced User" Emergency Earthquake Alert provides an early warning report on the time of occurrence and estimated epicenter of an earthquake when the amplitude of the P-wave or S-wave reaches 100 gal or more at one or more observation points of the Japan Meteorological Agency's multi-functional seismographs, or when a magnitude of 3.5 or higher or a maximum seismic intensity of 3 or higher is predicted by analysis.

The "Advanced User" information prioritizes the first report to quickly notify the occurrence of the earthquake. If seismic waves are observed at two or more observation points, further analysis is conducted and information is updated with the second and third reports. As updates continue and the accuracy of the prediction stabilizes, a final report is issued, and no further alerts for that earthquake are released. If seismic waves are not observed at two or more observation points within the predetermined time frame, a cancellation report is issued, as it is judged to be noise (malfunction or false report). The first report contains a large margin of error and a high possibility of false alarms, such as those caused by lightning. As the second and third reports are issued and time passes, the accuracy improves.

The major differences between "Advanced User" and "General User" alerts can be summarized as follows: "Advanced User" alerts provide precise and sufficient understanding of point information, while "General User" alerts provide information on a wider area (broad regions) to ensure that the expected disaster reduction effect is fully realized.

The "Advanced Users" feature allows users to rehearse or train for earthquake disaster prevention in practical situations by using actual emergency earthquake alerts delivered according to the user's preferences, for example, issuing alerts for predicted seismic intensity of 3 or higher (as it is possible to miss tremors at intensity 2). On the other hand, the "General Users" feature is rarely used because it only issues alerts for when earthquake damage is expected, such as in the case of a "warning".

While errors are unavoidable due to the technical limitations of the emergency earthquake alert system, if it is determined that the predicted seismic intensity is 3, users can understand that "(1) the actual seismic intensity is not 7, (2) there will not be any major tremors, and (3) there will not be any major damage". This is one of the "reassuring" effects of the advanced users' emergency earthquake alerts that is not present in the "warning" alerts for general users.

The trial operation of the emergency earthquake alert system by the Japan Meteorological Agency began on February 25, 2004. During the Niigata-Chuetsu earthquake in October 2004, the emergency earthquake alert was reported in Moriya City, Ibaraki Prefecture, before the arrival of seismic waves, and this was recorded on video. Additionally, the emergency earthquake alert was recorded on video in homes in Tokyo during the Niigata-Chuetsu offshore earthquake in July 2007.

Starting on August 1, 2006, emergency earthquake alerts were delivered in advance to specific industries that were deemed to have a good understanding of the characteristics of the system and could use the information without confusion. These industries include lifelines such as gas, electricity, and railways (e.g., stopping gas supply before major shaking occurs to prevent fires, and stopping trains using emergency communication to prevent accidents during earthquakes) and hospitals (protecting patients during surgery from earthquakes).

As of March 2007, more than 400 institutions, including local governments, railway operators, electricity, gas, manufacturing, and broadcasting companies, had completed the necessary procedures with the Meteorological Business Support Center to receive the advanced service. Some municipalities conducted training using the city and town disaster administration radio for providing information to a wide area, and this practice has expanded to other municipalities since October 2007.

"Advanced Users alerts", although it can be received by general individuals using computer or smartphone apps, if these characteristics are not well understood, confusion can arise. In addition, depending on the specifications of the app, further confusion may be caused. In the false report that occurred around 17:09 on August 1, 2016, although the Japan Meteorological Agency had announced a cancellation report, information was not deleted for a long time due to some apps not being able to automatically send cancellation reports, causing confusion for users of the apps.

"General Public" Emergency Earthquake Alert
Providing information to the public through television, radio, and facility-wide broadcasts can lead to confusion if implemented too easily. Therefore, sufficient efforts were made to raise awareness of the manner of utilizing information and the characteristics of the information. Some posters were created for this purpose, which featured popular characters such as "Ultra Brothers" (Ultraman, Ultra Seven, Ultraman Jack, Ultraman A, and Ultraman Taro) and leaflets for children featuring "Crayon Shin-chan (The Nohara Family and Kasukabe Defense Force)." After such promotional activities, full-scale operations were launched on October 1, 2007.

For the "General Public" alerts, if earthquake waves are observed at two or more earthquake observation points and a maximum seismic intensity of less than 5 is predicted, the time of occurrence of the earthquake, estimated epicenter, location of the epicenter, and the names of regions expected to experience an intensity of 4 or higher are reported promptly. After further analysis, if a region previously predicted to experience a seismic intensity of less than 3 is now predicted to experience an intensity of 5 or less, a follow-up report is issued. In this follow-up report, newly predicted regions with an expected seismic intensity of 5 or less and regions expected to experience a seismic intensity of 4 are announced. Furthermore, as of October 2012, follow-up reports are limited to those that are issued within 60 seconds of the earthquake detection.

Note that after the Great East Japan Earthquake on March 11, 2011, prediction accuracy was significantly reduced due to faults in observation points and frequent aftershocks and induced earthquakes, resulting in an increase in errors and false alarms. However, the accuracy has been gradually recovering, thanks to program improvements and a decrease in aftershocks, as seen in the 2011 fiscal year (April 2011-March 2012).

Details of the Announcement Status
When looking at the national announcement status of the "advanced user" (including cases that meet the criteria for "general use") alerts from October 1, 2007 to the end of February 2011, the number of announcements was:


 * Monthly (24-75 times)
 * Annual (120-622 times)
 * Monthly average (about 45 times)
 * Annual average (439 times).

In March 2011, when the Great East Japan Earthquake occurred, the number of announcements was significantly higher than before the end of February 2011, with 1,191 announcements per month.

In April 2016, the number of announcements increased significantly due to the impact of the Kumamoto earthquake, with 228 announcements per month, which is much higher than the monthly average of about 88 from January 2012 to the end of March 2016.

Regarding the "general use" warnings, a total of 17 warnings (including 1 false alarm) were issued from October 1, 2007 to March 11, 2011, before the Great East Japan Earthquake occurred. After the main shock of the Great East Japan Earthquake and thereafter, a total of 100 warnings (including false alarms, as of January 27, 2012) have been issued. As of August 8, 2013, 137 warnings have been issued since October 1, 2007, and 33 of them did not observe seismic intensity 3 or higher. As of February 25, 2023, a total of 259 warnings have been announced since October 2007.

Number of emergency earthquake reports
The total number of emergency earthquake reports from October 1, 2007, to the end of November 2022.

List of announced alerts
Source:

Annotations are added to alerts with seismic intensity of 6- or above or those with notable importance.

Prediction accuracy
For earthquakes where seismic intensity of 4 or higher was observed, or earthquakes where seismic intensity of 4 or higher was predicted in the Emergency Earthquake Alert, the score is calculated as the percentage of regions where the observed and predicted seismic intensity levels are within plus or minus one level. The score is calculated based on the final report of the alert if one was issued, or on the predicted seismic intensity level in the final forecast if no alert was issued.

Note: Each year is represented by its fiscal year. Fiscal years start in April of each year. Until 2009, the number of earthquakes with high seismic intensity was small, and the score exceeded 70%. However, after the Great East Japan Earthquake on March 11, 2011, aftershocks occurred one after another, and since several earthquakes that occurred almost simultaneously were treated as one large earthquake, the score decreased. Subsequently, the program was modified to exclude small earthquakes from the prediction calculation, and the score increased to 78.6% in 2012. Since then, there have been technical improvements and the accuracy has been increasing.

Note that the proportion of "misses" during the operation from the start to March 31, 2022, is 23% (58/250) for false alarms and 39% (85/219) for missed earthquakes.

Television and radio broadcasting
The emergency earthquake alerts that are broadcasted on TV and radio can be selected in different formats by each broadcasting station, such as whether or not to display the epicenter location, display of strong shaking by region, prefecture, or sub-unit of seismic intensity report. For example, NHK displays alerts as: while commercial stations display them as: or The way the information is displayed can vary among broadcasters. The information displayed on the screen is usually 3 lines long and displayed on a single page.

In addition, some TV stations do not display the words "Emergency Earthquake Alert (JMA)" on their screens, and in cases where the alert covers a wide area, such as the rarely used "Hokuriku" and "Koshin" areas, the alerts are displayed by region name, which may make it difficult for viewers to understand. As a general rule, NHK broadcasts emergency earthquake alerts nationwide on both terrestrial and BS broadcasting, while commercial broadcasters broadcast on terrestrial waves only within their respective broadcast areas, and BS and CS satellite waves (excluding some broadcasting companies) are nationwide like NHK. Therefore, if an emergency earthquake alert is announced outside the coverage area of commercial terrestrial broadcasting, the alert will only be broadcast on NHK's terrestrial waves. It should be noted that the Open University of Japan is exempt from the Disaster Broadcasting Regulations under the Broadcasting Act, and therefore, the university does not provide emergency earthquake alerts on either TV or radio (this also applies to tsunami warnings and advisories).

Since its introduction on October 1, 2007, NHK and Nippon TV have used NHK's unique chime sound (created by Tatsu Ifukube) as the alert tone, while other commercial stations have used a similar sound to the voice used for news alerts as their chime sound. Due to the recommendation by the Japan Meteorological Agency to use NHK's chime sound, more broadcasting stations have started to use it (although they can still use their own alert sounds). This chime sound won the Good Design Award in 2020.

Regarding the display of the epicenter, the location name of the epicenter is used as the reference for earthquake information, but due to the number of characters, multiple regions may be combined or the name of the location may be simplified. When the epicenter is under the sea, NHK displays it as "Earthquake: Occurred off the coast of XX Prefecture (e.g., Ibaraki Prefecture)," while commercial stations display it as "Earthquake: Occurred off the coast of XX" (e.g., "Earthquake: Occurred off the coast of Fukushima"). If the epicenter is on land, the earthquake is displayed as "Earthquake: Occurred in XX Prefecture" (e.g., "Earthquake: Occurred in Chiba Prefecture") with the prefecture name displayed (Hokkaido is divided into four regions: Dohoku, Donan, Dotou, and Doshin).

日本放送協会 (NHK)
NHK has been broadcasting emergency earthquake alerts on all TV, AM, and FM frequencies since October 1, 2007. However, these broadcasts are only for domestic audiences, and NHK World, the international broadcasting service, does not air emergency earthquake alerts on its television broadcasts (NHK World Japan and NHK World Premium), including the chime, automated voice announcements, and on-screen captions. However, during simultaneous broadcasts of domestic news programs on NHK World Premium, if an emergency earthquake alert is issued, the information will be broadcast as is. On the other hand, NHK World Radio Japan (shortwave and satellite digital radio) does not broadcast emergency earthquake alerts during its international broadcasting exclusive time slots (which do not receive simultaneous domestic broadcast waves), but during simultaneous domestic broadcasts with Radio 1, FM broadcasting, and general television broadcasts (only during "NHK Nodo Jiman" broadcast), it is directly transmitted through the shared radio/FM network line and therefore, it is broadcast worldwide and not only in Japan.

In addition, the Internet simultaneous distribution/IP simulcast radio services used by NHK Radio Broadcast 3 Waves (Radio 1, Radio 2, FM) ("NHK Net Radio Rajiru Rajiru" and commercial radio portal "radiko") cut the chime and automated voice announcements, resulting in silent broadcasts, and only the news studio's announcement of the emergency earthquake alert is broadcast. Since March 1, 2020, "NHK Plus," the Internet simultaneous distribution (General and E-Tele), has also been broadcasting emergency earthquake alerts with a delay of about 30 seconds.

After the chime for the emergency earthquake alert is played twice, on television (including interruptions during local programs), the bottom half of the screen displays the message "Emergency Earthquake Alert (Japan Meteorological Agency)," followed by text such as "Be cautious of strong shaking in XX" and a map of the predicted epicenter and cautionary areas with the names of the prefectures shown in a caption. During the following minute, or until the seismic intensity information is announced in live broadcasts, an automated voice announcement plays twice, saying "(Chime twice) This is an emergency earthquake alert. Please be cautious of strong shaking" (voiced by Masao Suematsu, a former NHK announcer). On AM, FM broadcasting, and radio international broadcasting (only during simultaneous domestic broadcasting in Japan), regular programs are forcibly interrupted, and the automated voice announces the affected prefecture and region.

Example
The news program's announcers have been trained to respond appropriately during emergency broadcasts (including live broadcasts other than news programs). While the chimes and automatic voice message are playing, they do not say anything. Once it has ended, they will repeat, and continue to repeat this message. However, they only display the epicenter on the screen. On the other hand, if an announcer who is not part of the news program responds, they will say, and during the message, they may also say, NHK (Japan Broadcasting Corporation) has different ways of broadcasting emergency earthquake alerts depending on the media platform. For radio broadcasts (primarily Radio 1 and Radio International), a broadcaster at the NHK Radio Center studio (usually from the news studio) will provide the alert after the automatic announcement ends. In rare cases, the news anchor may provide the alert during the automatic announcement.

For television broadcasts (primarily General TV), the news anchor will deliver the alert during a news program, while for other programs, the broadcast will be interrupted shortly after the alert is announced, and an anchor from the news center will deliver the alert.

NHK also announced on August 20, 2010, that it would implement a measure to display a red "Emergency Earthquake Alert" banner in white letters on the top of the screen and play a warning sound several seconds ahead of the actual alert through mandatory data broadcasting to account for the several seconds of delay in digital terrestrial broadcasting compared to analog broadcasting. This measure is implemented across all NHK stations. The "banner" lasts for 7 seconds, and the warning sound lasts for 4 seconds. This reduces the delay by approximately 1.0-2.5 seconds.

This measure is implemented by 58 terrestrial broadcasters, including the five major Tokyo broadcasters and four major Osaka broadcasters, as of June 2013. However, the color, position, and content of the banner may vary depending on the station. For instance, some broadcasters, such as Nippon TV, may include additional text, such as "earthquake in XX" or "epicenter in YY", along with the earthquake alert banner. The warning sound is played simultaneously with the banner.

NHK also broadcasts emergency earthquake alerts through its in-house broadcasting system in its facilities, including NHK Hall, Studio Park, and the Minna no Hiroba Fureai Hall (audio content is the same as that of radio broadcasts). The alerts are also broadcast on subchannels of General TV, Educational TV, and BS channels. Even for local broadcasts (General TV, Educational TV, Radio 1, Radio 2, and FM terrestrial broadcasts), the alert may be broadcast even in areas where the earthquake did not occur, depending on the content of the alert.

Private broadcasting
Private broadcasters were cautious about broadcasting emergency earthquake reports, but since October 2007 on TV and from October 1, 2007, on Nankai Broadcasting (RNB Radio), from November 2007 on Shizuoka Broadcasting (SBS Radio), and from February 2008 on FM Moriguchi (FM HANAKO), and from April 2008 on other radio stations, they started broadcasting emergency reports.

On the radio, there were concerns that listeners might lose their composure as normal programs are suddenly cut off, and an automatic voice message is played regardless of whether it's a live or recorded program. Therefore, when it was initially introduced on April 1, 2008, emergency earthquake reports on private radio stations in the Tokyo metropolitan area (including Chiba, Saitama, and Kanagawa prefectures), Osaka, and Nagoya were only broadcast when the predicted maximum seismic intensity in the broadcast area was 5+ (therefore, if the seismic intensity was 5-, it would not be broadcasted on private radio stations, but would still be broadcasted on NHK). As of October 2019, private radio stations in the Tokyo and Nagoya areas still follow this standard, but for some private radio stations in Osaka, the standard was changed to "earthquake intensity of 5- or higher" from 10:00 a.m. on January 7, 2019, which is almost the same as NHK's standard.

In the case of terrestrial TV broadcasting, even if an emergency earthquake warning is broadcasted by major commercial TV stations in Tokyo, it may not be broadcasted in areas that are not affected. However, in some cases, information that there was an emergency earthquake warning may be conveyed in news and information programs even in areas where it was not broadcasted. (However, even if an emergency earthquake warning is issued outside the Kanto region, it will not be mentioned in news and information programs of major commercial TV stations in Tokyo, and it will be conveyed like a regular earthquake warning, after a while from its occurrence.) Many commercial stations use the same chime as NHK. In addition, Japan TV (terrestrial, BS Nippon TV, and Nippon TV News 24 common) inserted an announcement saying "This is an emergency earthquake warning" (the voice was Kihiko Murayama, a former announcer of the same station) after the chime, but no other station followed suit.

After that, since it was difficult to understand only with the chime sound, some stations also took the same action as NTV. As an example of other stations in Tokyo following suit, TBS announced "Emergency earthquake warning" (the voice was Reisuke Yanagisawa, a TBS 954 information caster, currently a TBS radio caster), and TV Asahi had the same announcement as NHK saying "This is an emergency earthquake warning. Please be cautious of strong shaking" (the voice was Hiroko Ichikawa, a former announcer of the same station). However, Fuji TV (terrestrial, BS Fuji, and CS common) only had four chime sounds without an announcement until March 2013, but from April of the same year, an announcement similar to NHK's began to be played after four chimes (the voice was Ikko Mukaisaka, a former announcer of the same station. As of 2023, the chime has been changed to two). Until TV Tokyo moved to Roppongi in November 2016, they only had one chime without an announcement, but after the move, they began to play an announcement similar to NHK's after four chimes, like Fuji TV used to do [Note 32] (NHK owns the copyright of the chime). In order to compete for one second, it is broadcasted not only during program broadcasts but also in the form of being overlaid during CMs and sponsor credits.

In the six major commercial radio stations in Tokyo, a pre-announcement special program was simulcast on January 17, 2008, in a joint production. After that, in March, three FM radio stations in Tokyo and surrounding areas also participated in joint announcements.

Starting with July 1, 2008, all 12 Kansai-area commercial broadcasters introduced earthquake early warning systems within the 2008 fiscal year. The seven private broadcasters in the Tokai region also introduced the system on September 1 of the same year. The only station without the system, FM Gifu, introduced it on January 1, 2009, making all stations equipped with the system. In the case of a strong earthquake predicted to occur anywhere in the country, Nippon TV's NEWS24 interrupts its regular programming and switches to a breaking news screen displaying the time of occurrence, maximum predicted seismic intensity, the spread of the earthquake waves, and areas where strong shaking is expected (within the map range). This is the only system of its kind used by commercial television broadcasters, including CS channels (automated voice broadcasts used on terrestrial television are also included). WOWOW has slightly different criteria and will issue a breaking news announcement if an earthquake with a seismic intensity of lower 6 is expected. In the future, the standards may be changed based on user feedback.

On BS11, a character superimposition is displayed through data broadcasting, and only the built-in audio of the receiving equipment is sounded (there are no chimes or announcements). It can be hidden during playback (excluding some models).

Furthermore, the use of G-Guide for terrestrial digital broadcasting, One-Seg, and BS digital broadcasting is being considered. However, some stations, such as Gunma TV, have delayed introducing the system. Although most broadcast stations on internet simultaneous distribution and IP simulradio "radiko" are cut off like "Rajiru ★ Rajiru", some stations, such as J-WAVE, are broadcast without being cut off. However, the radiko website states that "the information may not be accurate due to delays" and "radio receivers should be used for earthquake disaster prevention".

Some specialized CS channels do not have the system, such as the Shop Channel, which has not had a function to report earthquake early warnings since its inception. However, due to the increase in earthquake activity caused by the Great East Japan Earthquake and the impact of the headquarters being forced to stop broadcasting, they have started to provide information through a caption during earthquake occurrences.

CATV
In the CATV field, the emergency earthquake warning system (master unit and sub unit) is relatively inexpensive and offered as an option. JCN provides rental terminals that receive "advanced user" emergency earthquake warnings, which announce the estimated seismic intensity and remaining seconds (5-0) until the shaking starts. In addition, some CATV broadcasting stations that also operate community FM radio use this emergency earthquake warning system simultaneously for their own community broadcasting.

Some cable TV providers also offer equipment for public facilities (such as prefectural facilities and municipal offices) free of charge.

After starting operation
After the system was put into operation, a magnitude 4.9 earthquake with a maximum intensity of 5+ occurred on October 1, 2007 at around 2:21 a.m. with its epicenter located in western Kanagawa Prefecture. The general public earthquake alert was scheduled to be provided at 9 a.m. on the same day, but due to the timing of the earthquake, it was not announced to the public and only the stations that had planned to use only caption subtitles and map displays carried out the earthquake report in the conventional manner.

Note that NHK and the five key stations in the Tokyo area (NTV, TV Asahi, TBS, TV Tokyo, and Fuji TV) display both maps and caption subtitles, but some local stations and other independent stations display only caption subtitles. If a map is displayed on TV, it is expected that important parts of the program content may be obscured by the map display. Some people may find the map display inconvenient, while allowing only caption subtitles to be displayed is acceptable. Particularly, in drama series, variety shows, and anime programs, complaints may flood in. Therefore, there is a possibility that more stations may use the conventional caption subtitle method as a compromise.

The first example of a "general public" alert being issued was the earthquake off Miyako Island in Okinawa Prefecture on April 28, 2008 at 2:32 a.m. Emergency earthquake alerts were broadcast on all media except NHK Radio 2 (which was off the air at the time) and NHK World (TV and radio). However, since the epicenter was offshore and there were no seismographs on the seafloor, seismic waves were observed only after they reached land. As a result, the warning was issued almost after S-waves had reached almost the entire island due to a delay in calculation. Since it was late at night when the earthquake occurred, many people could not learn about the emergency earthquake alert.

Also, the emergency earthquake alert for the earthquake off the coast of Ibaraki Prefecture at 1:45 a.m. on May 8, 2008, was issued about 58 seconds after the shaking began. During a news broadcast on the public broadcaster, an emergency earthquake alert was suddenly issued, causing confusion, such as the screen being switched and the emergency earthquake alert caption disappearing, and the start of the program "JAPAN Navigation". This was because it was announced just before the start of the next program, and the news program could not be extended.

Satellite data broadcasting
There was a mobile broadcasting service called "S-band disaster prevention information" for providing emergency earthquake alerts via satellite. Even if lifelines are cut off due to a large earthquake, if power lines are secured, it is possible to receive emergency earthquake alerts from a satellite, making it suitable for disasters. Some receiving terminals also have automatic correction using GPS even if the location is changed. Note that the mobile HO! service has already ended, so the service is no longer available.

Facility and wide-area broadcasting
As part of the Ministry of Education, Culture, Sports, Science and Technology's "Disaster Medicine" project, experimentation and verification of utilization have been conducted at the National Hospital Organization Disaster Medical Center in Tachikawa, Tokyo since 2003. As of April 2008, the hospital has implemented coordination with all building broadcasts, elevator stops at the nearest floor, automatic door opening, radiation device stops, information display machines, and local seismometers (responding to earthquakes from nearby epicenters).

In the field of "customer attraction facilities," Isetan department store has implemented linkage with in-store broadcasting at all 10 stores nationwide. Especially in department stores where there are many unspecified numbers of people, it is necessary for not only staff but also customers themselves to be aware of calm behavior in order to minimize confusion during an earthquake.

In other customer attraction facilities and public facilities where the system has been completed, the service has been available since October 2007.

In addition, the "Guidelines for Emergency Earthquake Alert-Compatible Emergency Broadcasting Equipment" (JEITA TTR-4701A) of the Japan Electronics and Information Technology Industries Association stipulates that when receiving the "Emergency Earthquake Alert (Warning)" announced by the Japan Meteorological Agency, business broadcasting (background music, guidance broadcasting, time announcements, etc.) and fire announcement broadcasting should be interrupted, and a total of 15 seconds or less of NHK's chime sound and a male voice saying "It's an earthquake. Please remain calm and protect yourself" should be broadcast throughout the building.

Emergency earthquake alerts via local government disaster prevention administrative radio using the National Instantaneous Warning System (J-ALERT) of the Fire and Disaster Management Agency have also been available since October 1, 2007. The service has started from some municipalities where the system has been completed.

Mobile phones
To enable the reception of emergency earthquake alerts on mobile phones, NTT DoCoMo, au (KDDI, Okinawa Cellular Telephone Union), and SoftBank (under the SoftBank and Y!mobile brands) each developed their own delivery systems and platforms, and added the receiving function to their new models released in 2007. For DoCoMo and SBM, the Cell Broadcast Service (CBS) broadcasting system standardized by 3GPP is used. For LTE dual-mode devices, including tablets, the Earthquake and Tsunami Warning System (ETWS) is used because CBS notifications are not suitable due to the communication characteristics of LTE. For au, which uses CDMA2000, a separate method called BroadcastSMS, formulated by 3GPP2, is adopted.

Support for smartphones was delayed, but the need for it increased after the Great East Japan Earthquake, and compatible models were released by various manufacturers for Android devices since the summer of 2011. Some already-released models also became compatible with software updates, with the addition of the Emergency Earthquake Alert feature as a standard function for iOS 5 on iPhones.

Several applications are available for smartphones, such as those for Android and iPhone, but all require initial setup. RC Solution has developed an app called "Yurekuru Call for iPhone" that can receive emergency earthquake alerts for iPhone and Android devices, which is available for free on the App Store. It uses the Advanced Emergency Earthquake Alert function for notification, but delays or failures may occur depending on the network usage. Apps such as "Namazu Alert β" that notify users of earthquake alerts for Android devices are also available, and real-time notification is possible experimentally, although there is no guarantee that the notification will always be delivered.

NTT DoCoMo
NTT DoCoMo provided its "Area Mail" service free of charge starting on December 10, 2007. The first compatible devices were the FOMA 905i series, which were released sequentially from November 26, 2007, and some of the FOMA 705i series, which were scheduled to be released sequentially from February 2008 and were compatible with FOMA high-speed. Starting from some of the 2010 winter models, and all of the Xi dual-mode devices and tablets released from 2011 winter models onwards, the notification method was switched from the CBS method to the ETWS method. However, some of the compatible devices released from the 2011 winter model only support emergency earthquake alerts.

Since the release of the "Photo Panel 04" in March 2012, the device has been compatible with receiving Area Mail notifications using a digital photo frame.

au (KDDI and Okinawa Cellular Telephone Union)
KDDI and Okinawa Cellular Telephone began providing the Emergency Earthquake Warning (EEW) service using C-mail for free on March 25, 2008. The first compatible devices were most of the models in the spring 2008 lineup that were released gradually from January 9, 2008.

As it is necessary to respond promptly in an emergency, the alert tone (a siren sound that repeats "three beeps with a one-second pause" until the content is confirmed) cannot be adjusted in volume, but only set to "ring or silent" (silent mode). Also, all reception history, including false alarms, is saved.

The digital photo frame SP03, released in September 2011, supports the EEW service.

On January 31, 2012, the "Emergency Alert Mail," which includes email notifications from the government and local authorities, began in addition to the EEW service. On smartphones (IS series), the "au disaster preparedness app" receives the Emergency Alert Mail. The app is pre-installed on IS11N and IS14SH released on December 23, 2011, and is also scheduled to be pre-installed on IS12F to be released in January 2012. The app is also provided through updates to existing Android 2.2 or later devices, sequentially.

Note that for smartphones, some devices that do not have the "au disaster preparedness app" pre-installed also support the EEW service with a separate app (such as SOI11).

For feature phones, F001 and all models released after the summer of 2012 support the Emergency Alert Mail level.

SoftBank brand
On May 30, 2007, SoftBank announced the development of an emergency earthquake alert distribution system, similar to those of other companies. At that time, the service was announced to be provided "within the fiscal year 2008", but it was delayed and was launched on August 25, 2010 in some areas. At the time of the service launch, the available areas were limited to the entire Kansai region, Tokai, Tohoku (7 prefectures), Chugoku, Shikoku areas, and some areas in the Kanto region. On October 7, 2010, nationwide support was completed.

On September 16, 2009, SoftBank released its first compatible model, the 831N, for its mobile phones. At a press conference held on November 4, 2010, President Masayoshi Son (at the time) said, "Models will gradually increase in the coming year," hinting that the models to be released in 2011 and beyond will be sequentially compatible. On April 18, 2011, SoftBank announced that it plans to equip all mobile phones and smartphones to be released in the future, except for some models to be released in the first half of fiscal year 2011, with an emergency earthquake alert function. It was also announced that the emergency earthquake alert function would be added by software update to seven models of smartphones that had already been released, but support for two models produced by HTC was later canceled. On July 11, 2011, support for emergency earthquake alerts was added by software update to the 840N. This was the second SoftBank 3G terminal to be supported.

The digital photo frame, 008HW (PhotoVision), which was released in September 2011 and is equipped with the Android OS, also supports emergency earthquake alerts. Later, it also became compatible with emergency alert emails.

From January 30, 2012, SoftBank started a service of emergency alert emails, which included emergency earthquake alerts, for some smartphones. The 105SH supported emergency alert emails from its initial release for devices other than smartphones. In addition, SoftBank plans to update the emergency earthquake alert app to the emergency alert email app for some terminals that have the emergency earthquake alert app installed.

Y!mobile Brand
With the launch of the Y!mobile brand in August 2014, devices that were already being sold under the old brand at that time, as well as devices under the Y!mobile brand, have essentially become unified in terms of content, despite having different sending sources and methods.

In terms of communication methods, there are three styles: "Telephone Service (Type 1 and 3)" (provided by SoftBank Mobile), "Telephone Service (Type 2)" (provided by the former E-Access), and "PHS Service" (provided by the former Willcom). For "PHS Service," only devices that have been continued from the old brand are limited to "Emergency Earthquake and Tsunami Warnings." For "Telephone Service (Type 1 and 3)" and "Telephone Service (Type 2)," disaster evacuation information is also included.

For contracts prior to July 2014 without the transition of the applied contract terms and conditions to plans after August of the same year, please refer to the content of the old company below.

E-Access
Regarding support, it had not been made clear for many years, but on March 7, 2013, it was included in the emergency alert email scheduled to be provided on the same day and started to be offered. The GL07S, the company's first LTE smartphone, which was released on the same day, became the first device to support the service.

For EMOBILE 4G-S compatible devices, they will be provided through SoftBank's MVNO contract and will be offered in accordance with the emergency alert email service (SoftBank).

WILLCOM/WILLCOM Okinawa
As of August 2012, there were no compatible models for PHS.

However, for the terminals offered in combination with PHS terminals for sale (when the new WILLCOM flat-rate plan GS is used as the basic fee plan) using WILLCOM CORE 3G terminals, services similar to those provided by SoftBank Mobile contracts are offered for all except voice and international roaming. Therefore, if the terminal is compatible with SoftBank Mobile, it can be used up to that level. (As of May 2012, there is no support for terminals with voice.)

The WX04K, released on June 21, 2012, was the first WILLCOM voice terminal to support earthquake early warning systems (later, an update added support for emergency alert emails), but the data line is not on the company's own line and is only carried out on the WILLCOM CORE 3G (SoftBank Mobile network version) network, so even for earthquake early warning systems, it follows the contents of SoftBank Mobile.

From November 14, 2013, the service will be available for PHS single contract terminals. WX11K and WX12K compatible models will also be released. For dual-mode terminals, services (emergency alert emails) on the SoftBank Mobile network will continue as before.

Disney Mobile
As of December 2011, only three smartphones (DM009SH, DM010SH, DM011SH) and a digital photo frame (DM001Photo) under the Disney Mobile brand were compatible with the Disaster Message Board service, and Disney Mobile 3G devices were not supported.

From the release of DM012SH in February 2012, new Disney Mobile devices were also compatible with the Disaster Message Board service including emergency earthquake alerts. Additionally, the four aforementioned devices could be updated to support the Disaster Message Board service up to the level of emergency earthquake alerts between March and April 2012.

Rakuten Mobile
Rakuten Mobile, which entered the mobile communication service market as a mobile network operator (MNO) in 2019, delivers emergency earthquake alerts as emergency alert emails.

MVNO (Mobile Virtual Network Operator)
Due to their use of the major mobile carriers' (MNO) networks, even if you have a contract with an MVNO (Mobile Virtual Network Operator), you can receive emergency alerts sent by the MNO on models that support emergency alerts.

However, depending on the mobile phone terminal, the display function for emergency alerts may not be available, the alert tone may not sound, it may not work with training emergency alerts, the notification may be adjustable, or it may operate with test signals that should not activate it, etc. The actual behavior of emergency alerts depends on the implementation of the mobile phone terminal.

Radio receiver
There are devices and software that can detect the general public earthquake early warning broadcasted on radio and transmit the emergency announcement. The emergency earthquake early warning for the general public sends an alarm saying "(Chime) This is an emergency earthquake early warning...." so people can prepare and respond a few seconds before the earthquake begins. The warning is issued before the severity of the earthquake is determined, so the details of the earthquake itself must be grasped separately as "earthquake information" on TV or radio after the shaking has stopped. If the radio is turned on before the earthquake occurs, the emergency warning broadcast can be heard.

Special radios, called emergency earthquake early warning devices, automatically turn on when the power is on standby, and the chime sound can be heard in the middle. The reason why you can't hear it from the beginning of the chime sound is that there is no mechanism to turn on the radio with the emergency earthquake early warning, as described later. In a mild earthquake, the shaking subsides and the power returns to standby mode and becomes quiet again after a while. In ordinary households, radio receivers such as emergency earthquake early warning devices are placed in the center of the house, and the volume is set high so that anyone in the house can hear the warning, even when they are sleeping.

Note that unlike emergency warning broadcasts, there is no mechanism in the emergency earthquake early warning system to turn on the TV or radio.

NHK and private broadcasters adopt a unique chime sound called "Houchi-on" recommended by the Japan Meteorological Agency for the Emergency Earthquake Warning System. As a result, radios referred to as "Emergency Earthquake Warning Systems" or "Earthquake Tsunami Alarm Systems" are equipped with a function that automatically switches on from standby mode and allows the listener to hear the emergency earthquake warning by detecting the electrical signal of the chime sound internally.


 * Takacom EDR-100/100AM radio, evacuation drill mode function, original sound source output function, external control output, paging function


 * Iris Ohyama
 * EQA-001
 * EQA-101
 * Alexon EEW100M radio, compatible with FM radio, with external audio input and external control output
 * Uniden EWR200, compatible with emergency earthquake warning and emergency broadcast
 * Yamazen YEW-R100, which is an OEM product of Uniden EWR200 and sold under the YAMAZEN brand
 * FRC (referred to as "Disaster Prevention Radio" by the company)
 * NX-109RD
 * FC-R119D (with specific low-power radio)

By using the emergency earthquake warning broadcasted by radio stations, no information reception fees or specific line usage fees are required. In addition, radio waves can be used, making it available even in areas where broadband cannot be installed. However, it is necessary for the receiving station to support the broadcast of the Emergency Earthquake Warning System. In addition, the service quality (speed, target area, etc.) of the breaking news provided may vary depending on the receiving station.

As of December 2008, the cumulative shipment of emergency earthquake warning receiver terminals by forecast business permit holders was 130,000, with a goal of 260,000 by FY2013.

PC, internet
Weathernews started providing a paid service called "The Last 10-Second" using existing internet connections and computer terminals starting October 15, 2007. It requires a PC with Windows 2000 or later and an always-on internet connection. As of April 2008, it is expensive for individuals to introduce dedicated terminals that respond to emergency earthquake alerts, but the service is characterized by its ability to provide services inexpensively by utilizing existing equipment. It falls into the category of advanced user emergency earthquake alerts, and if there is an earthquake with a magnitude of M3.5 or seismic intensity of 3 or higher that occurs in the country or its surrounding seas, it is possible to receive all of them by setting.

ANET (Anet) started selling EQMessenger, a receiving software for ANET Alert that encrypts earthquake alert source information and predicted seismic intensity at user locations, and the time until the arrival of the major motion (S-wave), starting July 7, 2008. When the predicted seismic intensity exceeds the set value, it pops up a map screen with the same warning sound as NHK, displaying the epicenter, evaluation points, and arrival of earthquake motion graphically.

In addition, free software called "SignalNow Express" has been available since September 2010, which allows advanced users to receive emergency earthquake alerts. Other software that receives information from strong motion monitors, such as "EqWatch", "Kiwi Monitor", and "JQuake", is also available.

Internet terminals
Internet terminals are provided not only for personal computers but also for dedicated terminals connected to NTT's Flets line. It is necessary for the Flets line to be compatible with IPv6. In the NTT East region, application for IPv6 addition service is required for Flets ADSL. In the NTT West region, application for IPv6 addition service is required for both B Flets and Flets ADSL.

As a provider of breaking news services, it is necessary to use the "Emergency Earthquake Warning Flets Type" service provided by NTT Communications. At the time of the announcement, data is transmitted to the terminal by IPv6 multicast.

Terminals that can receive the "Emergency Earthquake Warning Flets Type" include the following as of 2011:


 * NTT East Hikari Phone Router (wireless LAN type) *Provided only in East Japan


 * NTT East and West Japan Emergency Earthquake Warning Receiving Terminal DW-100
 * Released on November 20, 2008. Discontinued in April 2011 in East Japan.


 * Sanyo Electric TEL-LANW60 Home Telephone
 * Released on June 20, 2008. "Advanced User Emergency Earthquake Warning" is available. In addition, the "Emergency Earthquake Warning Mail Notification" function notifies up to three registered email addresses of emergency earthquake warnings such as "epicenter name," "predicted arrival date and time at the installation location," and "predicted seismic intensity" when the TEL-LANW60 installed has issued an emergency earthquake warning.


 * NTT East and West Japan Flets Phone VP1000 and VP1500 *Currently only available in West Japan.

Intercom system for condominiums
A system that utilizes the intercom equipment and wiring within a building to distribute emergency earthquake alerts has already been released. This is achieved by installing internet and emergency earthquake alert reception equipment in the common areas of the building and connecting it to the intercom system. Emergency earthquake alerts received by the system are displayed on color monitors or announced through an alarm sound from the intercom master unit installed in each unit. While a specialized intercom model that supports emergency earthquake alerts is required, the advantage is that the intercom master unit, which is always on standby for visitors, can also be used for alerting residents. This system is being increasingly adopted, especially in newly built condominiums.

Issues and Countermeasures
The following are the technical issues related to the calculation of the Emergency Earthquake Early Warning:


 * In principle, the closer the region is to the epicenter, the shorter the time between the announcement and the shaking, and there is a possibility that it may not be in time. With the current observation network, in areas that experience significant shaking due to shallow earthquakes directly beneath the epicenter, the emergency earthquake early warning may not be issued in time (there are cases where the early warning reception and the shaking occur simultaneously, or shaking begins before the early warning is issued).
 * In areas where the observation point spacing is wide due to the state of the observation network, the time between the earthquake occurrence and the detection of shaking can be longer, and there is a possibility that the warning may not be issued in time. This tendency is more pronounced in earthquakes occurring on islands or in ocean trenches. When multiple earthquake waves are observed simultaneously, there is a possibility that they may be mistakenly processed as a single earthquake, resulting in an overestimation of the magnitude.
 * The larger the earthquake, the longer it takes for the shaking to reach its maximum intensity after it begins, increasing the likelihood of underestimating the magnitude.
 * The larger the earthquake, the higher the likelihood that high-frequency (short-period) shaking will saturate, increasing the likelihood of underestimating the magnitude.
 * Irregular waveforms such as those produced by linked earthquakes, deep-seated earthquakes, volcanic earthquakes, and artificial earthquakes can result in significant errors, leading to an underestimation or overestimation of the magnitude.
 * Differences in the vibration characteristics of the ground near each seismometer and differences in the underground structure of the seismic wave propagation path from the epicenter to the seismometer can lead to underestimation or overestimation of the magnitude.
 * There is a possibility of announcing an incorrect calculation due to errors in the seismometer or processing equipment programs.
 * If communication lines are cut off or power supply to the observation facility is interrupted due to earthquake damage or other disasters, the observation point becomes a blank area, and the time between the earthquake occurrence and the detection of shaking can be longer.
 * Isolated islands such as Miyakojima and Torishima do not have ocean bottom seismometers, which can lead to overestimation or underestimation.

The following are the issues related to transmission, publicity, and utilization:


 * Delay may occur depending on the method of transmission. There are technical and institutional issues that can be shortened.
 * The means and likelihood of receiving early warnings vary depending on whether the recipient has a receiving terminal and their living environment.

Location and Backup
The emergency earthquake warning system is installed in two locations nationwide: the main office of the Japan Meteorological Agency in Tokyo and the Osaka Regional Meteorological Observatory in Osaka. Normally, the system in Tokyo announces warnings. However, if the Tokyo system is not available, the backup function is provided by switching to announcements from the Osaka system. During renovation work in 2011, the Osaka system was used. The observatories of JMA have been undergoing renovations since fiscal year 2012 (Heisei 24) to add satellite lines and batteries capable of supplying power for 72 hours as backups.

Losses incurred during the processing leading up to the announcement
In order to issue a prompt report by analyzing observation data immediately following an earthquake, in regions close to the epicenter where P-waves and S-waves arrive almost simultaneously, the report cannot keep up with significant shaking. With current calculation formulas, magnitude is determined from waveforms three seconds after the arrival of P-waves, hence losses are incurred in the processing leading up to the announcement for a period of several seconds to several tens of seconds. If an earthquake were to occur at a depth of 0 kilometers, there would theoretically be a difference of about 2.3 kilometers per second; therefore, it can be considered that if distance from epicenter is within range of loss time multiplied by 2.3 kilometers before S-wave arrival, then it will not make it on time. In reality however there are differences due to depth and region so values may range from 2-4 kilometers per second. As an example: during an earthquake measuring M4.9 with maximum seismic intensity level 5 that occurred in western Kanagawa Prefecture on October 1st, 2007; even if such system was operational at that time and S-waves arrived almost simultaneously with P-wave detection in Hakone Town or Odawara City; since prompt reports were issued only after initial micro-motion detection for about 32 seconds this case applies.

On November 26th,2010 as part administrative evaluation efforts,the Ministry of Internal Affairs and Communications recommended improvements for alerts including emergency earthquake warnings.The reasons cited include one out twelve cases where "General Emergency Earthquake Warnings" reached all target areas ahead prior major shaking since its introduction in December ,2007 ; as well as five other instances where predicted seismic intensities were lower than actual ones thus no "General Emergency Earthquake Warnings" were issued

Losses due to post-announcement processing
In addition, there may be losses during the time between the Meteorological Agency's release of preliminary information and its distribution to the end-user. This is generally due to delays in distribution caused by using delivery services or licensed forecasting agencies, with distribution often being routed through the Meteorological Business Support Center.

It has also been found that digital broadcasting is slower than analog broadcasting in terms of delay after a news flash starts airing on television. This was reported as early as May 2008, and during the Iwate-Miyagi Inland Earthquake that occurred the following June, it became clear that terrestrial digital broadcasting and BS digital broadcasting were about 2-3 seconds slower than terrestrial analog broadcasting, while One-Seg was about 4-5 seconds slower. In September of that year, the Ministry of Internal Affairs and Communications requested technical development from both Digital Broadcasting Promotion Association and Radio Waves Industrial Association for shortening delays up to 0.5 seconds in terrestrial digital broadcasting; however, it was announced that changes would have to be made to receiver specifications. To reduce this delay time NHK implemented advanced text displays across all stations; five private stations in Tokyo and four regional stations in Osaka followed suit.

In radio broadcasts, it takes approximately five seconds before one can hear "Emergency earthquake warning (two chimes). An earthquake has occurred in (location)."

Loss and error in areas with a rough observation network
There are regions in Japan where the density of observation points, which serve as sources for emergency earthquake alerts, is low. These include remote islands such as the Izu Islands, Ogasawara Islands and Nansei Islands. In addition, similar situations occur when earthquakes occur in distant sea areas outside these regions. In these areas, it takes time to detect seismic waves at multiple observation points necessary for issuing emergency alerts. Furthermore, due to the small number of observation points, it is difficult to increase accuracy by comparing data from multiple points, making errors in earthquake epicenter location, magnitude and intensity more likely.

This problem was highlighted after a earthquake occurred off Miyako Island in Okinawa on April 28th 2008. The epicenter was located undersea without any seismic instruments installed on the ocean floor. Seismic waves were detected only when they reached Miyako Island and an alert was issued at 2:32:25 AM; however the shaking was felt on Miyako Island at 2:32:20 AM with a difference of about five seconds between detection and arrival times. If there had been any seismic instruments installed beneath the ocean surface there might have been a possibility of issuing an alert earlier than that time difference allowed for. Furthermore there was an error of around 30 kilometers southwards in determining the epicenter location compared to its actual position during this event. When another magnitude one earthquake occurred off Miyako island again on August 5th that year, its predicted intensity level was reported as three - much higher than what actually happened - while depth also deviated by about ten kilometers or so along with a magnitude error of around one point(Example: factial magnitude was 5, calculated was 7). The first report had even larger errors.

The same situation would occur if earthquakes originated from coastal areas instead of underwater locations. To determine their epicenters' depth is often difficult since only P-waves and S-waves are detected initially. Thus, their depths are usually announced as being around 10 km in depth. In the next stage of detecting seismic waves to issue a second alert, the epicenter and magnitude are calculated from P-waves and S-waves. The time difference between the first and second alerts is then used to estimate depth if it is extreme. This method works well for earthquakes like those mentioned before where there is an ocean floor beneath them but inland earthquakes often have more instruments installed in densely populated areas so that errors rarely occur.

For earthquakes originating from underwater locations, seismic waves cannot be observed at sea bed but can only be detected when they reach land, causing delays in issuing emergency alerts. As "general use" emergency earthquake alerts require at least two or more seismic instruments to detect shaking before issuing an alert, if only one instrument detects shaking closest to the epicenter location , no alert will be issued by that system at all (although "special use" reports may still report with greater error). If there is a significant distance between these two observing points then further delays may occur. Currently most observation points are located on land with some located on seabeds such as off Shizuoka coast through Hinata Bay where Nankai Trough Earthquake could occur and off Choshi coastal area through Kushiro coastal area where Japan Trench Earthquake frequently occurs along with Izu Island's nearby oceanic region having high earthquake activity concentration. Seabed observation points can help improve accuracy and speed up response times for reporting trench-type earthquakes while also helping predict tsunamis; however setting up these systems requires considerable cost and effort which has limited their deployment thus far.

Error in earthquake predictions
The Japan Meteorological Agency states that the specific predicted seismic intensity values come with an error margin of about ±1, and thus its "general public" announcements do not specify the exact intensity value but rather describe it as "strong shaking." Additionally, for its "general public" announcements that use a criterion of a "maximum predicted seismic intensity of 5-weak or higher," the agency announces predictions up to an intensity level of 4 in certain regions due to two reasons: (1) errors in estimating seismic intensities and (2) the possibility that a predicted magnitude 4 could eventually escalate to magnitude 5- due to further fault movement. Although not announced through general public alerts, it is possible for actual tremors to be stronger than expected.

The cause of errors in predicting earthquake intensities can be traced back to differences in the ease with which ground motions propagate across different regions' terrain (orientation, wave velocity, frequency characteristics, decay rate), as well as calculation discrepancies resulting from abnormal waveform data during initial seconds. These issues can be resolved by incorporating programs that adjust for local geological variations; however, some areas – especially those lacking sufficient investigation such as seafloors – remain challenging. Improvements are being pursued continuously.

Furthermore, when multiple earthquakes occur simultaneously or aftershocks follow immediately after mainshocks – such as those observed during swarm earthquakes – early movements may be overestimated. For example, on April 21st before general public alerts were implemented one event measuring up to seismic level 4 was detected by JMA's monitoring system while another measuring up to level 5-weak was detected by a disaster-prevention research station's instrument and yet another registering up until level 6-weak was observed by Tokyo University's seismometer at Izu Peninsula's eastern shores following an earthquake originating from there; however JMA had announced maximum expected levels reaching seven due partly to overlapping seismic waves, leading to a significant error. Since its formal introduction, the major cases of prediction errors in the emergency earthquake early warning system that were announced to some users before the start of the "general public" alert operation (9 a.m. on October 1, 2007) are shown in the table on the right. In earthquakes with a maximum seismic intensity of weak 5 or higher (9 cases in total, 4 of which are shown in the table on the right), the maximum seismic intensity exceeded the maximum predicted seismic intensity. Note that prediction accuracy is not uniform, and simple comparisons cannot be made between cases due to changes in prediction technology and the database used as a reference.

When operated for general use, significant errors were observed in the early morning of July 24, 2008, during the earthquake that struck the northern coast of Iwate Prefecture. In reality, the earthquake was estimated to have a magnitude of M6.8 and a depth of 108 kilometers, and was observed to have a seismic intensity of weak 6 to 4 along the northern coast of Iwate Prefecture (both provisional values). On the other hand, the maximum predicted seismic intensity (including the affected area) in the emergency earthquake warning was "about 4" or "weak 5". Specifically, the maximum predicted seismic intensity in the first five reports, which were intended for "high-level users", was "about 4", and the predicted magnitude ranged from M5.8 to M6.5. The sixth report, which was intended for "general users" and subsequent reports, predicted a seismic intensity of "weak 5" and a magnitude of "M6.9", but the warning did not reach the entire Iwate Prefecture in time. The Japan Meteorological Agency cited two reasons for the error: 1) when the epicenter of an earthquake is deep, there are fewer cases where the seismic intensity increases significantly, so the accuracy of the prediction formula used to issue emergency reports is not high, and 2) the earthquake had a gradually increasing waveform. Initially, after the start of the "general use" announcement, earthquake magnitudes were often underestimated compared to actual values. Subsequently, the Japan Meteorological Agency improved the calculation formula used to determine the magnitude, and after conducting a re-prediction for this earthquake, it was found that a warning could be issued in 4.4 seconds. This program improvement has been in operation since August 3, 2009.

In the main shock of the Tohoku-Pacific Ocean Earthquake (Great East Japan Earthquake) that occurred in 2011, the emergency earthquake warning for general use was only issued for the Tohoku region, and the 14th report, which predicted a seismic intensity of weak 5 in the northern part of Ibaraki Prefecture, was published after the "60 seconds from initial detection" update condition, so the emergency earthquake warning was not issued for Aomori Prefecture, the Kanto region, and the Chubu region, where strong tremors of seismic intensity 5 or higher were observed. In addition, although the magnitude was estimated to be 4.3 in the first earthquake detection report, which was issued after 5.4 seconds, the Japan Meteorological Agency's Meteorological Research Institute cited the fact that the amplitude in the first few seconds was extremely small as the cause.

Furthermore, because many of the earthquake observation points in the Tohoku region were damaged during the earthquake, it became difficult to issue timely emergency reports for earthquakes of a certain magnitude.

In addition, the problem of being unable to accurately transmit information when multiple earthquakes occur simultaneously in distant locations during aftershocks or induced earthquakes became apparent. For example, on March 12, an emergency earthquake warning was issued stating that the western part of Kanagawa Prefecture had a seismic intensity of strong 5 to weak 6, but the actual earthquake had a magnitude of 2.0 and no points of observation reported feeling the earthquake. Almost at the same time, a magnitude 4.1 earthquake occurred with its epicenter in Nagano Prefecture, and it is believed that the two earthquakes were mistakenly linked as a single large earthquake. In addition, on April 12, an emergency earthquake warning was issued with incorrect information stating that the source of the earthquake was off the east coast of Chiba Prefecture and that the seismic intensity was weak 7 in the Hamadori area of Fukushima Prefecture, when it should have been a seismic intensity of weak 5 off the east coast of Chiba Prefecture. As a result, cases of predicting a seismic intensity greater than the actual value occurred frequently.

To address this problem, the Japan Meteorological Agency revised its system by excluding small-scale earthquakes that were not the subject of emergency earthquake warnings (alerts) among the almost simultaneous earthquakes from the calculation target, thereby reducing the frequency of mistakenly linking two earthquakes. This system revision has been in operation since August 11 of the same year.

False alarms
Due to technical problems with earthquake meters and their characteristics, false alarms can occur in the emergency earthquake alerts. False alarms can be caused by meter malfunctions, abnormal current surges from lightning, bugs or misconfigurations in computer programs.


 * On September 1, 2007 (Disaster Prevention Day), a company's mistake in the emergency earthquake alert email distribution system caused about 5,000 subscribers registered in Sumida-ku, Tokyo to receive an incorrect email stating that a "magnitude 5 earthquake had occurred".


 * On July 14, 2008 at 7:41 pm, an earthquake occurred off the coast of Chiba Prefecture. Due to a setting mistake in the acceleration criteria of a single observation point's earthquake meter, an erroneous first report was released for "advanced users", which caused confusion due to the erroneous information output from some receiving terminals. The first report was incorrect, but the second report accurately predicted the earthquake, so a general emergency earthquake alert was not released. The Meteorological Agency apologized for the false alarm on the day of the announcement and admitted that the meter had not been inspected once since its installation in December 2003. It was reported that the receiving terminal had passed the Meteorological Agency's inspection, and an investigation of all manufacturers of receiving terminals is planned. In this incident, due to a mistake in setting the acceleration criteria for the earthquake meter at the Choshi Tennozudai observation point in Chiba Prefecture, the incorrect first report was released from the Meteorological Agency stating "near Choshi City, Chiba Prefecture, with a maximum seismic intensity of weak 5 or greater" when it should have been set at 100 gal or more instead of mistakenly being set at 10 gal or more. The second report corrected the mistake after 10.6 seconds had passed. The observed acceleration was 12 gal, the maximum seismic intensity was 2, and the magnitude was estimated to be M3.6. JR East was able to determine that it was a false alarm before the announcement was made due to its own observation network, but some transportation lines such as the Tokyo Metropolitan Subway suspended operation. In addition, several receiving terminals provided by the same manufacturer were unable to process the alert correctly, and false information without basis, such as an estimated magnitude of "M12.7" and an overestimated seismic intensity of "seismic intensity 7", was output. At elementary and junior high schools in Okazaki City, Aichi Prefecture, "M12.7, seismic intensity 6" was output, and some students took evacuation measures. The receiving terminal did not display the source information, so the students did not know that the earthquake was far away, and some were scared and shed tears. In addition, at the Foundation for Supporting Meteorological Business, which was the distributor of the alert located on the first floor of the Meteorological Agency building, the alarm sounded and "seismic intensity 7" was displayed.


 * On August 25, 2009, an earthquake occurred off the coast of eastern Chiba Prefecture, and a public earthquake warning was issued in the fourth report. However, no shaking was observed in this earthquake, and it was later deemed a false alarm. The cause was that the company that installed the "Chiba Sanpou" seismometer in Minamiboso City, Chiba Prefecture, updated the emergency earthquake warning software unnecessarily during a software update, causing a malfunction. The information sent to the Japan Meteorological Agency contained data on shaking that was about 20 times stronger than the actual observed shaking, causing the prediction system to release incorrect information. In the case of a false alarm caused by lightning surges and other factors in the emergency earthquake warning, a "cancellation report" is issued, but in this earthquake, no cancellation report was issued. In addition, detailed information was only posted on the Japan Meteorological Agency's website, causing confusion for many people. The Japan Meteorological Agency sends out a cancellation report using the same mechanism as the emergency earthquake warning if a false alarm is issued despite no earthquake occurring, but does not send out alerts for earthquakes that meet the criteria. In this case, the head of the earthquake and volcano department and the head of the same department's management section were given severe warnings, and the responsible company was suspended from being nominated for one month.
 * On August 8th, 2013 at around 4:56pm, an urgent earthquake alert was announced stating that there was a possibility of tremors with a magnitude of M7.8 originating from Nara Prefecture, with a risk of shaking between seismic intensity 6 weak and 7 in Nara and Osaka prefectures. The alert range covered a wide area from Kanto and Chubu regions in the east to northern Kyushu in the west. In response, the Tokaido and Sanyo Shinkansen lines temporarily suspended services and there were delays and cancellations on local train lines and private railways. At the same time, an earthquake with a magnitude of M2.3 originating from the northern part of Wakayama prefecture occurred, but no locations with seismic intensity of 1 or higher were observed. Additionally, an underwater seismometer installed off the southeast coast of Mie prefecture detected noise at around the same time as this earthquake, and the Japan Meteorological Agency calculated the shaking based on this data, resulting in an overestimation of the tremors. As a result, the agency admitted to a false alert and apologized, and suspended the use of data from this seismometer. The agency stated that this was the first instance of an alert being issued without any actual tremors since the earthquake off the eastern coast of Chiba prefecture in August 2009, and this was the largest alert range ever. According to a survey conducted by Hiromichi Nakamori, a professor of sociology at Japan University, from August to September, among 1,000 residents in the areas covered by the alert, 47.7% thought that "really strong tremors were coming" when they heard the alert. Regarding the fact that the alert turned out to be false, 30.0% felt "angry" while 39.7% said "it couldn't be helped". In terms of the agency's response, the most problematic issue was that the announcement of the false alert was "delayed" according to 37.6% of the respondents.
 * On August 1st, 2016 at around 5:09 PM, a message for high-level users was sent out stating that a magnitude 9.1 earthquake had occurred with its epicenter in Tokyo Bay. However, there was no earthquake and a cancellation notice was immediately issued. The cause was a malfunction in the power supply of the observation point due to lightning strike. At that time, some smartphone apps that used high-level user information were not able to automatically send cancellation notices, causing confusion for users who continued to receive the information for an extended period of time.
 * On July 30th, 2020 at around 9:38 AM, an emergency earthquake warning was issued stating that a magnitude 7.3 earthquake with its epicenter in the southern offshore area of the Boso Peninsula was expected, with the possibility of strong shaking up to level 5. Strong warnings were issued for Kanto, Izu Islands, Tokai, Koshinetsu, and Fukushima prefectures. However, the actual earthquake that occurred was a magnitude 5.8 earthquake with its epicenter near Torishima, and no shaking above level 1 was observed. In response to the warning, the Tokaido Shinkansen was temporarily suspended due to power outages. The Japan Meteorological Agency held a press conference and apologized, stating that the warning system had incorrectly determined the epicenter and overestimated the magnitude, causing inconvenience to the public.

Overestimations in warnings that combine two or more earthquakes

 * Description of warnings for earthquakes with a seismic intensity of less than 5 weak and two or more simultaneous occurrences.
 * The actual epicenter represents all epicenters of simultaneous occurrences.
 * The earthquake with the maximum seismic intensity is in bold.
 * Earthquakes that did not observe the maximum seismic intensity are in normal font.
 * Earthquakes with a seismic intensity of less than 1 are indicated in parentheses (〜).

Earthquake warning for earthquakes that were not observed for their seismic intensity.

 * Warning issued for earthquakes that were not observed for their seismic intensity.

Public awareness of the alert system
Even if problems such as errors in the Emergency Earthquake Warning System are fixed, ultimately the problem lies in public awareness. No matter how accurate and reliable the warning is, if users (such as TV viewers) do not understand it correctly, disaster mitigation cannot be achieved.

The time between the announcement of the warning and the onset of strong shaking is usually only a few seconds. Therefore, if the response at the time of the announcement is not well known, there is a possibility that panic such as crowding people at emergency exits or cars abruptly braking and causing pile-ups will occur, leading to secondary disasters. Therefore, due to concerns about the early launch of the warning system to the public, the full operation that was planned for the spring of 2007 was postponed and the operation was decided to start in October.

In June 2008, about 8 months after the system's full operation began, a private survey company conducted a survey of people who saw the alert for the mainshock of the Iwate-Miyagi Inland Earthquake on TV or radio. As a result, half of the respondents said they thought it was an earthquake intensity report that had already occurred. The survey company also conducted another survey after the Iwate-Miyagi Inland Earthquake, where they received feedback such as "I thought it was an earthquake intensity report for an earthquake that already happened" and also "I held down furniture," indicating that the public awareness of the warning system was still lacking.

Fraud
According to the Japan Meteorological Agency, there are also malicious door-to-door salespeople who sell equipment falsely claiming that "the installation of the Emergency Earthquake Warning System receiver is mandatory," and there is concern that similar damages could occur as with the mandatory installation of home fire alarms.

Information disparity
Not everyone has a mobile phone with a receive function for the warning system, nor do they keep their TV or radio turned on at all times. Furthermore, warning announcements are not made on wired radio broadcasts. Therefore, not everyone is in a state where they can receive the Emergency Earthquake Warning System at all times, and there is an information disparity in the probability of individuals receiving the warning.

Furthermore, it has been pointed out that there were few people watching TV when the Suruga Bay earthquake occurred in the early morning of August 11, 2009 (M6.5, maximum intensity 6-). In the same individual, the reception environment varies depending on the situation, such as not having the TV on during sleep or work hours. In the Emergency Earthquake Warning System, which places a high priority on timeliness, as opposed to announcements such as preliminary tremor information and seismic intensity, the possibility or impossibility of receiving a warning once directly relates to whether you can know about the earthquake before the shaking or if your own safety is at stake. Studies are being conducted to increase the reception rate through technical means, but it is difficult to cover all citizens completely.

Since its introduction in 2007, there have been regional differences in the actual number of Emergency Earthquake Warning System (for the general public) announcements, and differences in awareness among residents are also believed to be a contributing factor. A survey conducted by Hiromichi Nakamori of the Department of Sociology, Faculty of Humanities and Sciences, Nihon University, of residents a year after the Tohoku Pacific Ocean earthquake, which led to a significant increase in Emergency Earthquake Warning System announcements in eastern Japan, found differences in awareness and evaluation of the system between eastern and western Japan. Strong earthquakes have occurred mainly in eastern Japan, which is why many prefectures in the Kinki, Chugoku, and Shikoku regions first received the Emergency Earthquake Warning System (for the general public) announcement during the Awaji Island earthquake with a seismic intensity of 6- that occurred on the morning of April 13, 2013. The Japan Meteorological Agency conducted a questionnaire survey of residents after this earthquake. The recognition rate of the Emergency Earthquake Warning System itself was 80%, and 70% of the respondents had actually heard the warning. Of those, about 50% understood its meaning accurately, while about 30% could not understand its meaning immediately, and about 15% did not know what to do.