The Japan Meteorological Agency (JMA) provides early warning information for earthquakes, tsunamis, volcano eruptions as well as severe weather and tropical cyclones, covering the whole country of Japan. The main purpose is to mitigate damages by providing key information that would allow preventive actions.

The JMA earthquake warning system issues alerts a few seconds or tens of seconds before an earthquake. Since October 2007, the warnings are transmitted through media like TV and radio and are used for other applications such as promptly slowing down trains, controlling elevators to avoid danger and enabling people to quickly protect themselves. The warnings include information on the estimated seismic intensity and the expected arrival time of principal motion when an earthquake occurs. This information is derived from prompt analysis of the data obtained from Japan’s seismic network.

In case of an earthquake, JMA estimates the possibility of a tsunami. If a damaging tsunami is expected, JMA issues tsunami warnings and advisories three minutes after the earthquake. In case tsunamis are originated by seismic events far from Japan, JMA takes a coordinated action with the Pacific Tsunami Warning Center (PTWC). Information provided by the warning system includes tsunami height and arrival times for affected locations in coastal areas.

The new volcano warning system was started in December 2007. The volcano monitoring systems issues warnings for possibly affected municipalities, providing the level of danger and the expected time for the eruption. JMA also provides warnings for extreme weather and tropical cyclones, in the form of maps and advisories.

Users of the systems are relevant authorities, including the Prime Minister, the general public as well as infrastructure providers such as railway companies.

References:
JMA Websites (http://www.jma.go.jp/jma/en/menu.html, http://www.jma.go.jp/jma/en/Activities/earthquake.html, accessed on February 20, 2012)
V. Grasso and A. Singh, UNEP (Dec 2011, forthcoming): Early Warning Systems: State-of-Art Analysis and Future Directions.