The Japan Meteorological Agency says the quake struck around 6 a.m at a depth of 10 kilometers (6 miles).
It warned people along the coast to move to higher ground.
Tohoku Electric said no abnormalities were found at its Onagawa nuclear power plant after the earthquake.
Tepco is checking to see if Fukushima No. 1 and No. 2 nuclear power plants have been affected, both of which were shut down following the quake in 2011.
The USGS initially measured the earthquake at 7.3, but later downgraded it to 6.9. Japan Meteorological Agency is still measuring the quake at a 7.3.
The earthquake was felt in Tokyo and its epicenter was off the coast of the Fukushima prefecture, Reuters reported.
There were no immediate reports of damage or injury. Live video feed above.
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