A strong earthquake has shaken north eastern Japan, triggering a one-metre tsunami in an area devastated by last year's Fukushima disaster.
The quake shook buildings as far Tokyo and led to the warnings being issued for coastal areas.
The earthquake had a preliminary magnitude of 7.3, the U.S. Geological Survey said. This was revised from an earlier estimate of 7.4.
The epicentre was 6.2 miles beneath the seabed.
The tsunami warning was issued for the coast of Miyagi Prefecture, which was hit by a devastating earthquake and tsunami on March 11, 2011.
That quake triggered fuel-rod meltdowns at the Fukushima nuclear plant, causing radiation leakage, contamination of food and water and mass evacuations in the world's worst nuclear crisis since Chernobyl in 1986.
Workers at the plant were ordered to move to higher ground after Friday's quake.
The government declared in December that the disaster was under control, but much of the area is still free of population.
Tokyo Electric Power Co, the operator of the Fukushima nuclear plant, reported no irregularities at its nuclear plants after the latest quake.
Japanese were posting photos of their TV screens with tsunami warnings on Facebook, asking each other whether they're safe, confirming their whereabouts.
"It shook for a long time here in Tokyo, are you guys all alright?" posted Eriko Hamada, enquiring about the safety of her friends.
Phone lines were overloaded and it was difficult to contact residents of Miyagi.
"Owing to the recent earthquake, phone lines are very busy, please try again later," the phone operator said.