It struck 20 kilometres west of the city of Iwaki, bordering the Pacific Ocean, at 02.25 am (1725 GMT). The epicentre was also about 50 kilometres southwest of the damaged Fukushima Daiichi Nuclear Power Station, which was crippled by the major quake and tsunami in March, 2011.
The Japan Meteorological Agency, which put the quake at magnitude 5.8, said no tsunami warning had been issued. The tremor caused buildings to shake in the capital Tokyo, 175 kilometres away, an AFP reporter there said. It came just hours after Japanese Prime Minister Shinzo Abe toured the Fukushima nuclear plant on Thursday, ordering its operator Tokyo Electric Power to fix radioactive water leaks there.
TEPCO said in a statement to Kyodo news agency that no abnormalities in radiation or equipment were observed at the plant after the quake.