A powerful earthquake measuring 6.6 on the Richter scale has struck off the eastern coast of Japan.
The tremor struck at about 2.30am (11.30am local time) but there are no reports of casualties or damage.
A 20cm tsunami was observed in Miyagi and other areas north of Tokyo after the country's weather agency warned that tidal waves up to 50cm would hit coastal areas in the region.
The Meteorological Agency has since lifted the tsunami warning.
Reports said buildings shook in Tokyo with the force of the quake, but there is not thought to be any serious damage or casualties.
