The quake produced powerful shaking along parts of Japan's eastern coast, and was felt strongly in Tokyo, but triggered no tsunami alert.
A strong earthquake has struck off the coast of eastern Japan, injuring dozens of people and triggering widespread power outages, but there appeared to be no major damage and no tsunami warning was issued.
The earthquake had a 7.3 magnitude and its epicentre was off the coast of Fukushima prefecture at a depth of 60 km (36 miles), the Japan Meteorological Agency said. It shook buildings for some time after it hit, shortly after 11:00 pm (1400 GMT).
Houses and offices in the capital Tokyo, hundreds of kilometres away, also swayed and shook.
No tsunami warning had been issued, the meteorological agency said.
Kyodo news agency reported at least 30 people injured, but gave no further details.
There were no immediate reports of significant damage, though local news broadcast images of a landslide on a highway.
A Reuters cameraman on location in Fukushima said his 10th floor hotel room shook for some time. One man at the hotel was taken to hospital after falling and hitting his head on a door, the cameraman said.
Although injured, the man was still able to walk, the cameraman said.
Television footage also showed broken glass from shop fronts.
Quick response from nuclear plants
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 Dai-ichi 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 facility.
The earthquake in Japan is upgraded from 7.1 to 7.3. Magnitude.— ∼Marietta (@MariettaDaviz) February 13, 2021
Nationwide 950,000 homes were without power due to power plants going offline.
No abnormalities have been found at the Fukushima 1 & 2 nuclear plants.
祈り 🙏🏻#earthquake #fukushima #Japanpic.twitter.com/heqZ6KSKFu
'All messed up'
Aftershocks continued to rattle the region in the hours afterwards and officials cautioned local residents to be vigilant. A handful of people were reported to have sought shelter at evacuation centres.
"We are working quickly to collect information but we still have no details to announce. There were some unconfirmed reports about landslides but we are still checking," Mikihiro Meguro, an official from the Fukushima prefectural government, told AFP.
Prime Minister Yoshihide Suga was called to his office, and broadcaster NHK said the government would set up a special liaison office to coordinate with affected regions.
Chief Cabinet Secretary Katsunobu Kato addressed reporters after midnight and said evaluations were under way.
"As far as damage, casualties and structural damage are being assessed," he said, adding that sections of the bullet train had been suspended due to power outages.
"Surveys are being done at Fukushima Daiichi nuclear plant," he said.
"We have received reports that Onagawa nuclear plant and Fukushima Daichi nuclear plant are not showing any abnorm ality," he added.
Images posted online showed broken glass at a shop and items spilled off the shelves at a supermarket.
Renowned author Yu Miri, who lives in Fukushima's Minamisoma city, tweeted a photo of her home, showing books, potted plants and other belongings strewn across the floor.
"My house in Odaka, Minamisoma city is all messed up," she wrote.
"I hear the ground rumbling. And another quake," she tweeted about an aftershock.
Aerial footage broadcast by NHK showed a hillside that collapsed onto a highway in Fukushima region, severing the road. It was not immediately clear if anyone was hurt.
The quake hit off of Fukushima just weeks before the 10th anniversary of a quake on March 11, 2011 that devastated northeast Japan and triggered a massive tsunami leading to the world's worst nuclear crisis in a quarter of a century, one centred at the Dai-ichi facility.
Earthquakes are common in Japan, one of the world's most seismically active areas. Japan accounts for about 20 percent of the world's earthquakes of magnitude 6 or greater.