A magnitude-6 earthquake jolted northern Japan early Thursday, dpa reported referring to the country's Meteorological Agency.
No immediate casualties or damage were reported. No tsunami warning was issued.
The quake occurred at 0:02 am (1502 GMT Wednesday) with an epicentre off the east coast of Aomori prefecture at a depth of 50 kilometres, the agency said.
No new damage was reported at the damaged Fukushima Daiichi Nuclear Power Station, operator Tokyo Electric Power Co said. The plant went into meltdown after it was struck by the March 2011 earthquake and resulting tsunami.
The twin natural disasters left more than 15,800 dead and about 3,000 missing in north-eastern Japan.