A major 7.2-magnitude earthquake struck off northern Japan on Friday, seismologists said, but no tsunami warning was issued.
The quake hit at 0305 GMT near the Russian-administered Kuril island chain, 1,490 kilometres (926 miles) north of Tokyo, the US Geological Survey said. It was located 122 km deep.
The quake rocked towns in the northernmost Japanese prefecture of Hokkaido.
"We have received no reports of damage so far," a spokesman at the Hokkaido police said, adding there were no reports of injuries.
The epicentre is close to the four Southern Kuril islands that were seized by Soviet troops in the closing days of World War II but are claimed by Japan.
The area is prone to earthquakes.