A 5.8-magnitude earthquake struck off large areas in eastern Japan, including Tokyo, early today, but there were no immediate reports of any damage, officials said.
The country's meteorological agency said there was no risk of a tsunami.
The tremor struck at 6:52 am (0322 IST Sunday), with the epicentre in the Pacific Ocean off Ibaraki prefecture, the agency said.
The quake struck about 30 kilometres below sea level, according to the agency.
Around 20 per cent of the world's most powerful earthquakes strike Japan.