Tokyo: A strong 6.3-magnitude earthquake struck off Japan`s southern Kyushu island on Friday, the US Geological Survey reported, but no tsunami warning was issued.
The epicentre of the quake -- which struck at 2:06 am (1706 GMT Thursday) -- was located 13 kilometres (eight miles) north of the city of Kunisaki-shi, USGS said.
The quake struck at a depth of 82 kilometres.
There was no immediate warning message issued by the Pacific Tsunami Warning Center.
More than 18,000 people died when a 9.0-magnitude undersea earthquake sent a towering tsunami barrelling into Japan`s northeast coast in March 2011 in the country`s worst post-World War II disaster.
Cooling systems at the Fukushima nuclear plant were knocked out, sending reactors into meltdown and forcing tens of thousands of people to flee.