A strong earthquake with a preliminary magnitude of 7.1 hit off the coast of eastern Japan on Saturday, shaking buildings and triggering widespread blackouts, but there appeared to be no major damage and no tsunami warning was issued.
The epicentre was off the coast of Fukushima prefecture at a depth of 60 km (36 miles), the Japan Meteorological Agency said. It hit at 11:08 p.m. local time (1408 GMT) and shook buildings in the capital Tokyo and elsewhere.
No tsunami warning had been issued, the meteorological agency said.
A Reuters cameraman on location in Fukushima said his tenth floor hotel room shook heavily for some time. One man at the hotel was taken to hospital after falling and hitting his head on a door, the Reuters cameraman said.
Although injured, the man was still able to walk, the cameraman said.
Footage from television also showed broken glass from shop fronts, while Kyodo news reported about a dozen injuries, although none immediately appeared to be grave.
Some 950,000 households were initially without power, government spokesman Katsunobu Kato told a briefing carried on public broadcaster NHK. The blackouts appeared to be concentrated in northeast Japan, including Fukushima and neighbouring prefectures.
There were no irregularities at the Fukushima Daiichi and Daini nuclear power plants, or at the Kahiwazaki-Kariwa nuclear plant, owner Tokyo Electric Power Company Holdings said.
The utility also said there was no change in the radiation levels around its plants.
Kato said there were no irregularities at the Onagawa nuclear facilities.
The quake hit off of Fukushima just weeks before the 10-year anniversary of the March 11, 2011, quake that devastated northeast Japan and triggered a massive tsunami that led to the world's worst nuclear crisis in a quarter of a century - one centred at the Daiichi facility.
Earthquakes are common in Japan, one of the world's most seismically active areas. Japan accounts for about 20% of the world's earthquakes of magnitude 6 or greater.