A magnitude-6.2 earthquake struck off the northeast coast early Monday morning, the U.S. Geological Survey said.
The agency said the quake struck at 2:32 a.m. in the Pacific Ocean at a depth of 70 km northeast of Hokkaido, close to the disputed Russian-administered Kuril Islands.
There were no immediate reports of damage. USGS had earlier given the quake a slightly higher magnitude-6.6 and a shallower 60-km depth reading.
The epicenter lay closest to Russian territory, 94 km from the town of Kuril’sk. The nearest Japanese city, Nemuro, is located 291 km from the epicenter.
The Kuril Islands are at the heart of a long-running territorial dispute between Japan and Russia.
They were seized by Soviet troops in the final days of World War II. Tokyo has insisted on the return of all four islands, which are known as the South Kurils by Russia and the Northern Territories by Japan.
Japan’s islands are situated at the juncture of several tectonic plates and experience a number of relatively violent quakes every year.
But thanks to strict building codes, even powerful quakes that might wreak havoc in other countries frequently pass without causing much damage.
In May, a strong magnitude-6.0 earthquake shook buildings in Tokyo, injuring 17 people.