A strong 6.9 magnitude earthquake hit northeastern Japan early 22 November, the country's meteorological agency said, issuing a tsunami warning for the region's coast including Fukushima prefecture.
A some three metre tsunami could hit the northeastern coast, the agency said, including Fukushima -- home to the Fukushima Daiichi nuclear power plant, site of one of the world's worst nuclear disasters.
The US Geological Agency said the quake, at a shallow depth of 11.3 kilometres, struck shortly before 6:00 am (local time) in the Pacific off Fukushima.
The nation's meteorological agency had earlier estimated the quake's magnitude at 7.3.
Japan sits at the junction of four tectonic plates and experiences a number of relatively violent quakes every year.