A 5.9 magnitude earthquake hit Japan's Honshu island on Saturday, the U.S. Geological Survey said, shaking Fukushima where crippled nuclear power plants are located, but local media said there was no tsunami warning.
USGS said the quake's epicenter was located 42 miles (68 km) east-northeast of Iwaki on Honshu. It was measured at a depth of 22.9 miles (37 km).
A spokesman for Tokyo Electric Power, which owns the nuclear plants, said no irregularities have been found at its Fukushkma Daiichi or Daini plants.
The national broadcaster NHK said there was no tsunami warning, and there were no immediate reports of casualties or serious damage.
The quake also jolted Fukushima's neighboring areas on Japan's pacific coast.