An undersea earthquake on this day in 1946 sets off a powerful tsunami that devastates Honshu, Japan. About 2,000 people perished and half a million were left homeless. This was particularly devastating to a community that was already reeling from the horrors of World War II.
Earlier in the year, on April 1, a tsunami had struck Hawaii, killing 159 people, but those waves had originated hundreds of miles from the islands. The earthquake that shook at 4:20 a.m. on December 21 was centered only 27 miles south of Honshu's Kii Peninsula. The tremor had a magnitude of 8.5 and caused some buildings on Honshu to collapse, including some housing being used by U.S. occupation forces.
Even worse, three major tsunamis headed toward Honshu and the smaller islands of Kyushu and Shikoku. Local geographic features determined how intense the waves were when they hit land and how much damage they caused. In some places, the water receded severely first, providing a warning to local residents who were familiar with the signs of an imminent tsunami. When the tsunami hit Honshu, 20-foot waves obliterated buildings from shorelines and about 2,000 ships were capsized as they were thrown around by the mass of water.
In all, 60,000 square miles were flooded by the waves and 40,000 homes were completely destroyed.