Since summer 2020, flags have been used in coastal areas to issue tsunami warnings/advisories (referred to here simply as "tsunami warnings").
Tsunami warnings are issued via TV, radio, mobile phones, disaster management radio, sirens, local alarms and other means. Visual notification using flags in coastal areas was also started in summer 2020 to help hearing-impaired people and swimmers, who may have difficulty hearing due to waves and wind. Immediate evacuation should follow any display of tsunami flags in coastal areas.
Tsunami flags feature a red and white checkered pattern, with a short side of 100 cm or more recommended for visibility. The flags have a design similar to that of the U-flag used internationally as a marine warning.
![]() Tsunami flag |
![]() JMA YouTube video: Evacuate immediately if you see a tsunami flag. |
![]() Display of a tsunami flag |
Video of a tsunami flag display (Japanese subtitles; 1 min.) |