A series of strong aftershocks continued to shake Japan Saturday morning, the US Geological Survey in Washington said, dpa reported.
Earthquakes measuring as high as 6.8 on the Richter scale were recorded off the east coast of Honshu, according to the US service that monitors earthquakes worldwide.
At least five aftershocks greater than magnitude 5.5 were recorded within an hour around midday (0300 GMT).
The Pacific Tsunami Warning Centre in Hawaii said a widespread tsunami warning remained in place for Japan, Russia, Mexico, French Polynesia, Pitcairn, Antarctica, Chile, Ecuador, Colombia and Peru.
The full extent of the damage in earthquake-ravaged Japan was revealed Saturday morning, after an 8.9-magnitude quake and devastating tsunami rocked the north-eastern part of the country, killing well over 1,000 people, the government said.