A magnitude-6.4 earthquake jolted north-eastern Japan Sunday, dpa reported according to the Meteorological Agency.
No immediate casualties or damage were reported and no tsunami warning was issued.
The quake occurred at 3:54 am with its epicentre off Fukushima prefecture at a depth of 40 kilometres, the agency said.
The same region was hit by a magnitude-9.0 quake and tsunami on March 11, which triggered the ongoing nuclear crisis at the Fukushima Daiichi Nuclear Power Station.
No immediate new damage was reported at the damaged plant.