Japan has escaped unscathed after a large earthquake rattled its east coast this morning, sending several tsunamis ashore.
The quake hit at 2.10am (6.10am NZT), about 290 kilometres off Fukushima, and was widely felt in Tokyo, 480 kilometres away. It was classified as magnitude 7.1 by the Japan Meteorological Agency; the US Geological Survey put it at magnitude 7.3.
The meteorological agency said the quake was an aftershock of the magnitude 9.0 earthquake and tsunami that struck the same area in 2011, killing about 19,000 people and devastating the Fukushima Dai-Ichi nuclear power plant.
Tsunamis of up to 40 centimetres were reported at four areas along the coast, but a tsunami advisory was lifted less than two hours after the quake.
Broadcaster NHK said there were no immediate signs of serious damage and television images of harbours showed calm waters.
''It [the quake] was fairly big, and rattled quite a bit, but nothing fell to the floor or broke. We've had quakes of this magnitude before,'' Satoshi Mizuno, an official with the Fukushima prefectural government's disaster management department, said.
''Luckily, the quake's center was very far off the coast.''
The meteorological agency reported tsunamis in Kuji city in Iwate prefecture and Soma city in Fukushima, Ofunato city in Iwate prefecture and Ishinomaki in Miyagi prefecture.
The operator of Japan's wrecked Fukushima nuclear plant said here was no damage or spike in radiation levels at the station after the quake.
He said some workers had been ordered to evacuate to higher ground after the quake, but that there was no damage or change in readings at radiation monitoring posts around the plant.
Ships were seen leaving a port south of the Fukushima Daiichi nuclear power station, where three reactors had meltdowns in 2011 after an earthquake and tsunami knocked out cooling and power, as a precaution after the tremor.
All but two of Japan's 50 nuclear reactors have been offline since a March 2011 magnitude 9.0 quake and ensuing tsunami triggered multiple meltdowns and massive radiation leaks at the Fukushima plant.
About 19,000 people were killed in the disaster.
A string of mishaps this year at the Fukushima plant has raised international concerns about the operator's ability to tackle the continuing crisis.
Worried Japanese regulators met with Tokyo Electric officials this week to discuss how to prepare for a typhoon that could dump heavy rain on Fukushima this weekend.
- AP and Reuters