Tokyo: A 6.4-magnitude earthquake struck off the east coast of Japan early on Monday, according to the US Geological Survey, but no tsunami warning was issued.
The epicentre of the earthquake was 41.7 kilometres beneath the Pacific seabed, less than 50 kilometres off the coast of Miyagi prefecture, the USGS said on its website, rating the risk of casualties and damage as low.
The Japan Meteorological Agency (JMA) put the quake at a magnitude of 6.1 and a depth of 50 kilometres.
Japan's media said no tsunami warning had been issued after the tremor, which hit just after 5.30 am (2030 GMT).