So far no victims and damage have been reported. There is no tsunami threat.
The epicenter of the earthquake was in the Pacific Ocean off the coast of the Fukushima prefecture and the seismic focus was at 90 km depth.
The residents of 14 of 47 prefectures including Tokyo felt the shocks.
The TEPCO company, which operates the Fukushima-1 NPP said the earthquake had not affected the course of restoration work at the NPP.
On March 11, 2011, a 9 magnitude earthquake hit the north east of Japan. It was followed by 14 meter tsunami. More than 17,000 people died.