A 6.8 magnitude earthquake has struck off northeastern Japan a short time ago.
A strong 6.8-magnitude earthquake has struck off the coast of northeastern Japan, but authorities have not issued a tsunami warning and there are no immediate reports of damage.
The quake struck at 6.12am (7.12am AEST) off the east coast of Japan's Honshu island in the Pacific Ocean at a depth of 38.9km, according to the US Geological Survey.
Japan's meteorological agency said there was no immediate tsunami threat from the quake, which hit 33km southeast of the nearest city of Ofunato.
Large areas jolted by the latest tremor were among those damaged by the 2011 quake and tsunami that killed more than 18,000 people and triggered a nuclear meltdown at the Fukushima power plant.
Wednesday's quake did not damage any of the nuclear reactors in the region, including those at the crippled Fukushima facility, Japan's public broadcaster NHK said.
All of Japan's reactors have been off-line since the Fukushima disaster.
Japan's islands are situated at the juncture of several tectonic plates and experience a number of relatively violent quakes every year.
But building codes are rigorous and regular disaster drills are held, helping to ensure that despite their frequency and magnitude, quakes usually pass without loss of life or significant damage to property.