The window of time from the announcement of an Earthquake Early Warning until the arrival of the main tremors is very short, i.e. a matter of seconds (or between several seconds and a few tens of seconds).
In areas that are close to the focus of the earthquake, the warning may not be transmitted before strong tremors hit.
When using data from only one seismograph, false Earthquake Early Warnings may occur as a result of noise from accidents, lightning or device failure.
There are limits to the accuracy of estimating magnitude, especially for large earthquakes.
It is difficult to separate earthquakes and provide accurate warnings when multiple earthquakes occur almost simultaneously or in close proximity to each other.
Seismic intensity estimation
There are limits to the accuracy of estimating seismic intensity by statistical attenuation formula, as well as limits to the prediction of land surface amplification.
The Japan Meteorological Agency plans to continue improving the accuracy and timing of the Earthquake Early Warning through joint research with the National Research Institute for Earth Science and Disaster Prevention, and also intends to make further efforts toward publicizing the Earthquake Early Warning.
- Back to the top page of Earthquake Early Warning
- What is the Earthquake Early Warning (or "緊急地震速報 (Kinkyu Jishin Sokuho)" in Japanese)?
- Examples of Response to an Earthquake Early Warning