A powerful earthquake rocked eastern Japan today, but no tsunami warning was issued and no damage was reported at the crippled Fukushima nuclear plant.
The US Geological Survey said the 6.0 magnitude quake, with an epicentre 10 kilometres deep, was centred 166 kilometres east-northeast of Tokyo, where correspondents said buildings swayed.
Japan's meteorological agency also located the quake off the coast of Ibaraki prefecture, south of the stricken plant.
A very small change of tidal level was forecast but was not expected to cause any damage.
Nuclear plant operator Tokyo Electric Power Co (TEPCO) said the stricken Fukushima Daiichi plant remained stable.
Office buildings in Tokyo swayed for around a minute when the quake struck at 1151 IST, but there was no sign of panic in a city well accustomed to tremors.
A 9.0-magnitude earthquake in March 2011 triggered a monster tsunami that killed more than 19,000 people and crippled the cooling systems at the Fukushima plant, causing meltdowns in some of its reactors.
Radiation leaked into the air, soil and sea around the plant, forcing tens of thousands of people to evacuate their homes.
A number of powerful aftershocks have shaken the region since the March quake.
Japan, located at the junction of four tectonic plates, experiences 20% of the strongest quakes recorded on Earth each year.
