The quake is one of the most powerful ever to hit Japan.
The United States Geological Survey said the earthquake had a magnitude of 8.9, and occurred at about 230 miles northeast of Tokyo and at a revised depth of about 17 miles. The Japanese Meteorological Agency said the quake had a magnitude of 8.8, which would make it among the biggest in a century.
The quake occurred at 2:46 p.m. Tokyo time and hit off Honshu, Japan's most populous island. The quake was so powerful that buildings in central Tokyo, designed to withstand major earthquakes, swayed.
