Tokyo - Quake shook buildings in the capital of Tokyo.
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 of the earthquake was off the coast of Fukushima prefecture at a depth of 60 km (36 miles), the Japan Meteorological Agency said.
The earthquake, which hit at 11:08pm local time (1408 GMT), and shook buildings in the capital Tokyo and elsewhere. The Meteorological Agency said no tsunami warning had been issued.
About 950,000 households were without power, government spokesman Katsunobu Kato told a briefing carried on public broadcaster NHK. He said there were no irregularities at two nuclear facilities, Fukushima Dai-ni and Onagawa. Authorities were still checking at Fukushima Dai-ichi, he said.
NHK said there were no reports of irregularities at another nuclear facility at Tokaimura, in Ibaraki prefecture.
The quake hit off of Fukushima just weeks before the 10-year anniversary of the March 11, 2011, quake that devasted northeast Japan and triggered a massive tsunami that led to the world's worst nuclear crisis in a quarter of a century.
Earthquakes are common in Japan, one of the world's most seismically active areas. Japan accounts for about 20 per cent of the world's earthquakes of magnitude 6 or greater