Tsunami Warning (Japan)

Japan has a nationwide Tsunami Warning system (Japanese: 大津波警報・津波警報・津波注意報). The system usually issues warnings a few minutes after an Earthquake Early Warning (EEW) is issued, should waves be expected, usually when a combination of high magnitude, seaward epicenter and vertical focal mechanism is observed. The tsunami warning was issued within 3 minutes with the most serious rating on its warning scale during the 2011 Tōhoku earthquake and tsunami; it was rated as a "major tsunami", being at least 3 m (9.8 ft) high. An improved system was unveiled on March 7, 2013, following the 2011 disaster to better assess imminent tsunamis.