Japan has a nationwide tsunami warning system . The system usually issues the warning minutes after an Earthquake Early Warning ( EEW ) is issued , should there be expected waves . 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 access the waves
2011 Tōhoku earthquake and tsunami
2011 Tōhoku earthquake and tsunami
Tsunami warning system