A 6.9-magnitude earthquake struck off Japan's Hokkaido island late on Saturday, the US Geological Survey reported, but there was no warning of a tsunami.
A destructive tsunami was not generated, said a release from the Pacific Tsunami Warning Center, while Kyodo news agency said there was no threat of tsunami, citing the Japan Meteorological Agency.
The quake hit at a depth of 103 kilometres (64 miles) at 23:17 pm (1417 GMT), about 109 kilometres west of Kushiro, Hokkaido, the USGS said.
There are no immediate reports of major damage from the quake, according to Kyodo.
A powerful 7.3-magnitude undersea quake off the northeast coast in December triggered a one-metre-high tsunami but no reports of fatalities.
In March 2011 a devastating earthquake and tsunami in the same area left some 19,000 people dead or missing and crippled the Fukushima nuclear power plant in the world's worst atomic disaster in 25 years.