[4][5] When an earthquake occurs, the Japan Meteorological Agency (JMA) estimates the possibility of tsunami generation from seismic observation data.
JMA also issues information on tsunami details such as estimated arrival times and heights.
[7] Immediately after an earthquake occurs, JMA promptly establishes its location, magnitude and the related tsunami risk.
In such cases, JMA issues an initial warning based on the predefined maximum magnitude to avoid underestimation.
Once the exact magnitude is determined, JMA updates the warning with estimated maximum tsunami heights expressed in quantitative terms.