Earthquake early warning system
An earthquake early warning system is a system of accelerometers, seismometers, communication, computers, and alarms that is devised for rapidly notifying adjoining regions of a substantial earthquake once one begins. This is not the same as earthquake prediction, which is currently not capable of producing decisive event warnings.
Time lag and wave projection
An earthquake is caused by the release of stored elastic strain energy during rapid sliding along a fault. The sliding starts at some location and progresses away from the hypocentre in each direction along the fault surface. The speed of the progression of this fault tear is slower than — and distinct from — the speed of the resultant pressure and shear waves, with the pressure wave travelling faster than the shear wave. The pressure waves are always smaller in amplitude than the damaging shear waves that are the most destructive to structures, particularly buildings that have a resonant period similar to those of the radiated waves. Typically, these buildings are around eight floors in height. These waves will be strongest at the ends of the slippage, and may project destructive waves well beyond the fault failure. The intensity of such remote effects are highly dependent upon local soils conditions within the region, and these effects are considered in constructing a model of the region that determines appropriate responses to specific events.File:Warning time Nepal Earthquake.jpg|thumbnail|Warning time given by the earthquake warning system of the Earthquake Network project during the May 2015 Nepal earthquake. The cross marker depicts the earthquake epicentre, while the dot marker shows the detection location.
Deployment
As of January 2026, China, Japan, Taiwan, South Korea, Israel and Transnistria have comprehensive, nationwide earthquake early warning systems that notify people in the affected areas via Cell Broadcast, TV alerts, radio announcements or via public address systems/civil defence sirens. Mexico, the United States, Canada, and India have regional earthquake warning systems which notify people using similar technologies. In particular, the Mexican Seismic Alert System covers areas of central and southern Mexico, including Mexico City and Oaxaca; ShakeAlert covers California, Oregon, and Washington in the United States and British Columbia, Ontario and Quebec in Canada; and India's only covers Uttarakhand state.Countries such as Guatemala, El Salvador, Nicaragua and Costa Rica have deployed systems that alert only specific users through applications that have to be installed individually on their smart devices, while Indonesia and Turkey are currently publicly testing similar opt-in systems. Romania and Italy have systems reserved for other purposes. Systems are currently being developed and internally being tested in Switzerland, Chile, Peru and Iran.
Nationwide systems
Japan
Japan's Earthquake Early Warning system was tested beginning in 2004 and became fully operational on October 1st, 2007, making it the first nationwide earthquake early warning system to enter service. The system was developed by the Japan Meteorological Agency in cooperation with the National Research Institute for Earth Science and Disaster Resilience and other institutions, was partly based on the earlier Urgent Earthquake Detection and Alarm System developed by Japan Railways in the 1990s, which was designed to trigger automatic braking of Shinkansen trains in the event of nearby seismic activity. While UrEDAS was limited in geographic scope and intended for infrastructure safety, the JMA's EEW system expanded this concept to include nationwide coverage and public alerts via television, radio, mobile phones, and other communication systems.Following the 2011 Tōhoku earthquake, researchers used gravimetric data to observe prompt elastogravity signals, changes in Earth's gravity field generated by the earthquake. These signals travelling at the speed of light, significantly faster than seismic waves, have been used to explore new models that could improve EEW lead times. Although still experimental, PEGS-based approaches represent a potential advancement in early detection, particularly for large-magnitude events.
Today, Japan's EEW system remains one of the most advanced in the world, continuously upgraded with new algorithms to improve accuracy and reduce false alarms, new sensor networks, and integration into infrastructure and automated response systems.
Taiwan
Taiwan's Earthquake Early Warning system was developed by the Central Weather Administration in collaboration with academic institutions such as the Institute of Earth Sciences, Academia Sinica, and the National Center for Research on Earthquake Engineering. The program began after the devastating 1999 Chi-Chi earthquake, which killed over 2,400 people and highlighted the need for rapid alerts to mitigate casualties.Initial work focused on research and internal alert capabilities began in 2001. The first operational version of the EEW system was launched for limited institutional use in 2009, and after a period of testing and upgrades, the system became publicly operational in 2014, becoming the second country in the world, after Japan, to implement a nationwide earthquake early warning system.
South Korea
South Korea's Earthquake Early Warning system is operated by the Korea Meteorological Administration, which has been developing earthquake monitoring and early warning capabilities since the early 2010s. Following Japan and Taiwan, South Korea became the third country to establish a nationwide EEW system, officially introducing it in 2015.Although South Korea experiences fewer and generally less intense earthquakes compared to Japan and Taiwan, seismic activity has increased in recent years, including notable events such as the 2016 Gyeongju earthquake and the 2017 Pohang earthquake which heightened public awareness and demonstrated the practical need for such a system.
Israel
Israel has been developing its Earthquake Early Warning system in response to seismic risks posed by the Dead Sea Transform fault zone, which runs along the country's eastern border. Although the region experiences relatively infrequent large earthquakes, historical records show several damaging events, such as the 1927 Jericho earthquake and the 1995 Gulf of Aqaba earthquake, prompting growing concerns about preparedness.The country's EEW efforts are led by the Geological Survey of Israel and the Israel Defense Forces, in coordination with the Home Front Command. In 2014, Israel launched a pilot EEW project designed to detect seismic waves in real time using a network of seismic sensors along the Jordan Rift Valley.
In 2022, Israel officially operationalized TRUAA as a public alert system integrated with its national emergency infrastructure. With this rollout, Israel became the fourth country in the world, after Japan, Taiwan, and South Korea, to implement a nationwide earthquake early warning system.
On October 31, 2024 residents across northern Israel, including Haifa, the Golan Heights, and Galilee, received an earthquake warning, however, the warning was later confirmed to be a false alarm, triggered by a controlled explosions in southern Lebanon during the Israel–Hezbollah conflict. The Geological Survey of Israel stated that the system's sensors had misinterpreted the shockwaves from the blasts as the initial seismic waves of an earthquake.
China
China has been actively developing earthquake early warning capabilities since the early 2000s, led primarily by the China Earthquake Administration and the Chengdu-based Institute of Care-life. The devastating 2008 Sichuan earthquake, which resulted in nearly 80,000 deaths and massive destruction, stimulated China's investment in nationwide earthquake early warning systems as well as the founding of the ICL.Unlike Japan, Taiwan, or South Korea, China's system did not begin as a single centralized effort. Instead, it developed regionally, notably in Sichuan and Yunnan provinces, where seismic risk was the highest, and combined into a single unique system starting from 2018. The first operational public EEW alerts were issued in Sichuan in 2011, using localized networks.
In 2024, China announced the completion of the world's biggest earthquake early warning system capable of providing alerts across all mainland China, becoming the fifth country to do so. Although China's nationwide system came after Japan, Taiwan and South Korea, it has rapidly grown to become the largest and most technologically ambitious EEW efforts globally, particularly in terms of geographic scale and integration with public infrastructure: it's composed by 16,000 monitoring stations, managed by 3 national centres, 31 provincial centres, and 173 prefectural and municipal centres.
Transnistria
In 2025, Interdnestrcom, the main telecommunications provider in the unrecognized territory of Transnistria, successfully launched an earthquake early warning. This made Transnistria the sixth territory worldwide to deploy a nationwide EEW system, following Japan, Taiwan, South Korea, Israel, and China.Regional systems
Mexico
Mexico's Earthquake Early Warning system began development following the 1985 Mexico City earthquake. In 1993, Mexico City issued what is considered the first earthquake early warning ever delivered to the public, marking the beginning of operational of the system. A second system was later developed for the state of Oaxaca in 2000 after the 1999 Oaxaca earthquake. In 2005, both systems were integrated into a unified national network known as the Mexican Seismic Alert System, managed by the Centro de Instrumentación y Registro Sísmico.Although SASMEX is the oldest EEW system currently in operation, its coverage remains limited to specific regions of the country. Warnings are currently disseminated via radio, public sirens, dedicated receivers and TV Alerts. In 2025 CIRES began testing cell-broadcast alerts, and became operational in 2026.