A strong earthquake struck off northern Japan early Saturday, shaking buildings in Tokyo but there was no risk of a tsunami. There were no immediate reports of injuries or damage.
The Japan Meteorological Agency said the quake measured 6.6 and hit at a depth of 60 kilometers (36 miles). The United States (US) Geological Survey put the preliminary magnitude at 6.8.
There was no major disruption in transportation, although Shinkansen bullet trains were temporarily suspended for safety checks and some local lines were delayed, the East Japan Railway Co said.
The quake was centered off the coast of Miyagi prefecture in northern Japan, the area devastated by the massive earthquake and tsunami in March 2011 that left about 20,000 people dead.
Japan's Nuclear Regulation Authority said no abnormalities were reported at nuclear plants, including the Fukushima Daiichi, which melted down following the 2011 disaster.