major tsunami warning
Official warning issued when a tsunami of 3 meters or higher is expected. Stronger than a regular 津波警報 (tsunami warning).
See also: 津波警報 (つなみけいほう)
The Japan Meteorological Agency issued a major tsunami warning.
If a major tsunami warning is issued, please evacuate to high ground immediately.
津波警報 warns of a tsunami of moderate height, whereas 大津波警報 is the highest-level alert issued when an extremely large, life-threatening tsunami is expected.
Compound of 大 (large) + 津波 (tsunami) + 警報 (warning).