A small tsunami wave has hit Japan's northeastern coastline after a magnitude 6.8 earthquake struck around 210km off the northern island of Hokkaido.

Local authorities issued an evacuation warning for coastal residents before the tsunami struck land.

The waves hit two locations in Aomori prefecture, which was one of the areas in Japan's northeast devastated by last year's disaster.

The earthquake struck at a relatively shallow 10km below the seabed at 6.09pm local time (9.09am Irish time).

A spokesman for Tohoku Electric Power, which operates two nuclear power plants in the country's northeast, said the facilities were unaffected.

Later, an earthquake with a preliminary magnitude of 6.1 hit east of Tokyo but no tsunami warning was issued and there were no initial reports of damage or troubles at nuclear plants in the area.

On Sunday, Japan fell silent to remember the almost 19,000 victims of last year's devastating earthquake and tsunami, which struck on 11 March.