"Long-period ground motion" will be added to the Earthquake Early Warning System

The announcement standards for Earthquake Early Warnings issued by the Japan Meteorological Agency have been changed, and from Wednesday, February 1, 2020, long-period ground motion classes will be added to the announcement standards for Earthquake Early Warnings.

Until now, Earthquake Early Warnings have been announced based on seismic intensity predictions, but from Wednesday, February 1, 2020, predicted values ​​of long-period ground motion classes will be added to the announcement criteria. , an earthquake early warning will be issued even if a long-period ground motion class 3 or higher is predicted.

[Classes announced as earthquake early warnings are 3 or higher]

The large shaking (seismic motion) that occurs during a large earthquake and has a long period (the time it takes for the shaking to make one round trip) is called long-period ground motion.

[Warning targets are high floors above 14th floor or buildings with seismic isolation structure]