The Japan Meteorological Agency says a 7.0-magnitude earthquake has struck off far northern Japan and far eastern Russia.
The tremor around midday Friday was in the Pacific Ocean at a relatively shallow depth of 10 kilometers (6.2 miles).
The agency said sea changes were possible but no damage was expected.
The epicenter was 58 kilometers (160 miles) east-northeast of Kuril'sk, Russia, and 528 kilometers (328 miles) northeast of Nemuro, Japan.
The area is almost 1,500 kilometers (930 miles) northeast of Tokyo.