A 5.6-magnitude earthquake on Tuesday struck northeastern Japan near the disaster-hit Fukushima nuclear plant but there was no fear of a tsunami, Japanese and US authorities said.
The quake struck at a depth of 42.3 kilometres (26 miles) in the Pacific Ocean 34 kilometres east-northeast of the town of Namie, the US Geological Survey said.
The Japan Meteorological Agency said there was no risk of a tsunami from the quake, which caused some swaying in high-rise buildings in Tokyo.
There were no immediate reports of damage or injuries though some local service train services stopped, public broadcaster NHK reported.
Tokyo Electric Power, operator of the Fukushima plant, said no abnormalities were detected.
A massive undersea quake on March 11, 2011 sent a tsunami barrelling into the northeast coast, leaving more than 18,500 people dead or missing and sending three reactors into meltdown at the Fukushima nuclear plant.
In November a powerful 6.9-magnitude quake sparked panic and triggered a one-metre (three-foot) tsunami that washed ashore at the Fukushima plant but caused no damage.
Japan sits at the junction of four tectonic plates and experiences a number of relatively violent quakes every year.