TOKYO: Japan issued a tsunami warning Wednesday after a major 7.2-magnitude quake struck 160 kilometres east off the main Honshu island at 0245 GMT, swaying buildings in the capital Tokyo.

A tsunami warning of up to 50 cm was issued for northeastern Japan, public broadcaster NHK reported.

Tohoku Electric Power said its Onagawa nuclear plant was operating normally after the quake. Tokyo Electric Power also said there was no impact on its power plants in the region.

Earthquakes are common in Japan, one of the world's most seismically active areas.

The country accounts for about 20 per cent of the world's earthquakes of magnitude 6 or greater.