An earthquake struck the northeast of Japan early on Wednesday, the area devastated four years ago, but there were no immediate reports of damage or injury and no tsunami alert.
The quake off the Tohoku region had a preliminary magnitude of 6.8, according to the U.S. Geological Survey, and 6.6 according to public broadcaster NHK. USGS originally reported the earthquake as 6.9 magnitude.
The quake was centred 74 miles (119 km) southeast of Morioka, Japan, at a depth of 24 miles (39 km), it said.
An NHK helicopter flying over the area showed no damage, and the network said it had received no reports of damage or injuries from the broad areas shaken by the quake.
There were no reports of the abnormalities at the wrecked Fukushima Daiichi nuclear plant or the nearby Daini plant, NHK said.
A Tohoku Electric Power Co spokesman told Reuters there was no abnormality seen at the Onagawa and Higashidori nuclear power plants.
Shinkansen bullet trains in the region were halted for checks, NHK said