A strong 6.5 magnitude earthquake hit eastern Japan on Wednesday, the US Geological Survey said, but local authorities said there was no risk of a tsunami.
The quake struck at 0018 GMT at a depth of 404 kilometres (251 miles), the USGS said.
"The epicentre is in the Pacific, hundreds of kilometres (miles) south of Tokyo. We see no risk of a tsunami," a spokesman for the Japanese weather agency said.
Fukushima operator TEPCO reported there were no new problems at the stricken nuclear plant.