A strong earthquake shook the Tokyo area and eastern Japan today, though no injuries or damage was immediately reported.
The Japan Meteorological Agency said the quake registered a magnitude of 6.9 but was centred offshore near Torishima, part of the Izu Islands about 600 kilometres south of Tokyo.
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 US Geological Survey measured the quake at 6.5 magnitude and said it was 404 kilometres 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 Dai-ichi 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 today's quake.
The eastern-central region of Japan is said to be due for a major quake and smaller temblors are common.