A moderate 5.4-magnitude offshore earthquake hit northern Japan on Monday, the US Geological Survey said. There were no immediate reports of casualties or damage and no tsunami alert was issued.
The quake struck at 2:26 pm (0526 GMT) in a narrow ocean strait between Aomori and Hokkaido
prefectures, 55 kilometres (35 miles) northwest of the city of Aomori, at a depth of 163 kilometres, the US agency said.
Around 20 percent of the world's most powerful earthquakes strike Japan.