A strong earthquake struck wide areas of north-eastern and eastern Japan on Wednesday, the Meteorological Agency said.
No tsunami warning was issued and there were no immediate reports of injuries or damage.
The agency said the magnitude-6.9 quake struck at 9.19 a.m. (5.49 a.m. IST), and was centred off Torishima, 600 km south of Tokyo, at a depth of 400 km.
Tokyo Electric Power Co said there were no abnormalities at its damaged Fukushima Daiichi Nuclear Power Station.
A quake of that magnitude is at the upper range of a “strong” earthquake capable of causing major damage to buildings in populated areas. Most buildings in Japan meet modern standards for earthquake resistance and would withstand shaking that might cause major damage elsewhere.
Despite the remoteness of the epicentre, tremors were felt from the north of the main island of Honshu to the west. In Tokyo, buildings swayed for several moments.
The national broadcaster NHK said some train lines stopped briefly for safety checks as a precaution. No tsunami alert was issued.
The U.S. Geological Survey measured the quake at 6.5 and said it was 404 km deep.
In March 2011, a magnitude 9.0 earthquake offshore of northeastern Japan, and ensuing tsunami, killed more than 18,000 people and devastated the coastline for hundreds of miles. It also crippled the Fukushima Daiichi nuclear power plant, causing meltdowns in three of its reactors.
Japan’s Nuclear Regulation Authority said no abnormalities were reported at Fukushima and two other nuclear plants in northern Japan that were shaken by Wednesday morning’s quake.
The eastern-central region of Japan is said to be due for a major quake and smaller temblors are common.