The country's meteorological agency said there was no risk of a tsunami from the quake, which hit at 9:13am (0013 GMT).
The epicentre was about 50 kilometres (30 miles) below sea level in the Pacific Ocean off Fukushima prefecture, some 200 kilometres (125 miles) from Tokyo, according to the agency.
Around 20 per cent of the world's most powerful earthquakes strike Japan.
Meanwhile, an earthquake measuring 5.4 on the Richter scale hit southwestern Greece also on Tuesday, according to the Athens Geodynamic Institute. Police said there were no reports of casualties and the tremor’s epicenter was south of the island of Zakynthos in the Ionian Sea.
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