A strong earthquake with a magnitude of 7.3 jolted Japan's northeast coast on Wednesday and left hundreds of thousands of residents in Tokyo without power.
The tremor, in the same region devastated by the magnitude 9 temblor 11 years ago that triggered the Fukushima nuclear disaster, occurred at a depth of 60 kilometres, 57 kilometres off the coast, the Japan Meteorological Agency (JMA) said.
It registered as high as a 6-plus on the Japanese shaking intensity scale in some areas -- too strong for people to stand -- and rattled buildings in the capital.
The JMA issued a tsunami warning for the region of as high as 1 metre (3.28 ft), with public broadcaster NHK reporting waves of 20 centimetres in some places.
Prime Minister Fumio Kishida told reporters his government was assessing the extent of any damage after arriving at his office following the tremor, which shook large parts of Japan.
Tokyo Electric Power Company 9501.T said that around 2 million households were without power, including 700,000 in the capital, and that it was checking the condition of reactors at Fukushima and other plants, public broadcaster NHK reported.
No damage had yet been reported at those or at oil refineries on the coast, government officials said.
The radiation leak from the Fukushima Daichi nuclear power plant was the worst nuclear crisis since the explosion at the Chernobyl facility in Ukraine a quarter of a century earlier.
Authorities warned residents in Fukushima, Miyagi and Yamagata prefectures to expect after shocks.
Sitting on the boundary of several tectonic plates, Japan experiences around a fifth of the world's earthquakes of magnitude 6 or greater.
