For example, during the 1896 Meiji Sanriku Earthquake (M 8 1/2), the perceptible ground motion was slight despite extremely large fault movement. Moreover, the earthquake occurred on the evening of the Boy's Festival Day (Tango-no-sekku) on the lunar calendar, and many people had gathered indoors for parties. This delayed evacuation, and is the reason cited for the drowning deaths of more than 20,000 people. In contrast, about 3,000 died from the tsunami during the 1933 Sanriku Earthquake (M 8.1), because the lessons learned from the tsunami of 1896 were applied and evacuation was conducted efficiently.

Following knowledge about tsunami can be instrumental in preventing the large-scale loss of life - tsunami may accompany earthquakes of M 6 or greater that take place offshore; the size of the tsunami that hits shore cannot be determined based on the perceptible ground motion; large tsunami may hit shore that are caused by earthquakes far away; finally, the initial tsunami may be followed by even larger succeeding tsunami.

The damage that can be caused by tsunami includes the destruction of buildings caused by flowing water or flotsam, the loss of fishing vessels, damage to the maritime hatchery industry and maritime facilities, and flood damage to farmland. Houses and fishing vessels washed away by tsunami sometimes result in the outbreak of fire. Finally, damage sometimes occurs by tsunami that move upstream.