TOKYO — A magnitude 7.3 earthquake struck Saturday off the coast of Japan's Fukushima prefecture, which was home to one of the world's worst nuclear disasters almost a decade ago.
The Japan Meteorological Agency said the quake — which it initially said had a magnitude of 7.1 — struck at 11:08 p.m. local time (9:08 a.m. ET) at a depth of 34 miles. Fourteen aftershocks were recorded, it said, adding that a tsunami warning had not been issued.
The quake was also felt in Japan's capital, Tokyo.
"There have been no anomalies reported from any of the nuclear facilities," Japanese Prime Minister Yoshihide Suga told a press conference. "Everything is normal."
Checks were still being carried out to determine the number injured, he said, urging people not to venture outdoors and to be prepared for aftershocks.
Chief Cabinet Secretary Katsunobu Kato told a separate news conference earlier in Tokyo that almost 850,000 households had been left without power in areas surrounding Tokyo and northern Japan.
"Where the tremor was felt the strongest, there is higher risk of structural collapse and landslides," a spokeswoman for the Japan Meteorological Agency told press in Tokyo. Adding that people should be cautious about tremors.
Fukushima became synonymous with nuclear disaster in March 2011 when the area was hit by a 9.0 magnitude earthquake — the strongest in Japan's history. A tsunami soon followed, leaving more than 15,000 people dead and 2,500 others still missing.
The deadly wall of water slammed through the walls of the Fukushima Daiichi Nuclear Power Plant, knocking out the power supply and causing three nuclear reactors to melt, spewing radioactive particles into the air. It will take decades to safely shut down the plant.
Space to store the 1 million tons of water — equal to 400 Olympic-size swimming pools — that must be pumped through the reactor to keep the fuel cool, is also running out. While the water has been treated to remove most of the dangerous radioactive components, traces of tritium remain.
Kato said the plant was being inspected but there was "no concern of a damage-causing tsunami" and "no anomalies" had been reported at the site. Investigations were continuing to make sure there was no structural damage, he added.
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The Tokyo Electric Power Company, which operates the plant, also tweeted that it had checked its facilities and "no abnormalities" had been detected.
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.
Arata Yamamoto reported from Tokyo and Adela Suliman from London.
Reuters contributed to this report.