Japan has issued a tsunami warning after a 7.3 magnitude earthquake struck off the country’s eastern coast.
The quake was felt in the capital Tokyo, media report.
The tsunami warning was issued for the coast of Miyagi Prefecture, which was hit by a devastating earthquake and tsunami in March 2011.
The wave hit the city of Ishinomaki, while the quake was also felt strongly in the capital, Tokyo.
The epicentre of the quake was about 245 km (150 miles) south-east of Kamiashi at a depth of about 36 km, the US Geological Survey said.
Miyagi was hit by a devastating earthquake and tsunami in March 2011.
The US-based Pacific Tsunami Warning Center said there was no threat to the wider Pacific Ocean but that a tsunami could be generated that was destructive for local coastlines.
There have been no immediate reports of deaths or injuries.
Warnings of the tsunami height have varied between 50 cm and 2 m.
Any such height would represent a far lower risk of devastation than the 10-11 metre tsunami that struck in 2011 but that since then the country has clearly become jittery about any shaking of the earth.
At the moment, he says, the damage appears to be on a limited scale, although even a one-metre tsunami could be a significant event.
Japan has issued a tsunami warning after a 7.3 magnitude earthquake struck off the country’s eastern coast
Evacuations have been ordered from some of the affected areas.
A presenter on state broadcaster NHK told viewers: “Remember last year’s quake and tsunami. Call on your neighbors and flee to higher ground now!”
Buildings were reported to have swayed violently in Tokyo.
Prime Minister Yoshihiko Noda cancelled campaigning for the 16 December election to return to his office.
Communications to Miyagi have proven difficult, with the high volume of telephone calls. Trains in the prefecture have been halted and the runway at Sendai airport closed.
English teacher John Heritage, who is in Tagajo in Miyagi Prefecture, said the earthquake was not as powerful as some he had experienced but was worrying as it went on so long.
“We’re now at an official evacuation centre with about 50 other people waiting to hear what to do next,” he said.
Other people reported being alerted to the earthquake prior to its arrival by Japan’s mobile phone-based warning system.
One tweeted that he was given 10 seconds and was able to slow his car before the shaking struck.
The USGS reported three aftershocks in the same area, of 6.2, 5.5 and 4.7 magnitudes.
The 9.0 magnitude quake that struck on March 11th, 2011, caused a devastating tsunami and left more than 15,000 people dead, with more than 3,200 missing.
That quake triggered a meltdown of fuel rods at the Fukushima nuclear plant, causing radiation leaks and mass evacuations.
The plant’s operator, Tokyo Electric Power, told Agence France-Presse there were no reports of problems there this time, although workers have moved to higher ground.
Japan marks one year commemoration of the devastating earthquake and tsunami, which struck the north-eastern coast, leaving 20,000 dead or missing.
The 9-magnitude quake, Japan’s most powerful since records began, also triggered a serious nuclear accident at the Fukushima Daiichi nuclear plant.
Thousands of people were evacuated as radiation leaked from the plant.
There were memorial services, and a minute’s silence was observed at the moment the quake hit, 14:46 local time.
The main memorial ceremony was held at Tokyo’s National Theatre, attended by Japan’s Emperor Akihito, Empress Michiko and Prime Minister Yoshihiko Noda.
“We shall not let our memory of the disasters fade,” Emperor Akihito said in a brief televised address.
“I hope all the people will keep the victims in their hearts.”
PM Yoshihiko Noda pledged to rebuild so that Japan could be reborn “as an even better place”.
Japan marks one year commemoration of the devastating earthquake and tsunami, which struck the north-eastern coast, leaving 20,000 dead or missing
Much of Japan came to a standstill as the minute of silence was observed.
Warning sirens sounded across the north-east of the country at the precise time the quake struck, 14:46 local time. Bells and prayers also reverberated across the country.
The earthquake struck about 400 km (250 miles) north-east of Tokyo on 11 March 2011.
Shortly after the quake, an immense surge of water enveloped the north-eastern coast as a tsunami swept cars, ships, and buildings away, crushing coastal communities.
The twin natural disasters claimed more than 15,800 lives, and more than 3,000 people remain unaccounted for.
In the Fukushima prefecture, where the Fukushima Daiichi nuclear plant is located, the impact of the disaster was particularly acute.
Radiation leaked from the plant after a series of fires and explosions damaged four of the plant’s six reactor buildings, with serious failures in the plant’s cooling system being at the heart of the problem.
A 20 km (12.5 mile) exclusion zone around the plant was put in place making tens of thousands of people homeless. Radiation means the area around remains uninhabitable.
The plant is in cold shutdown now and PM Yoshihiko Noda has promised that over the decades to come it will be decommissioned. He has also pledged to rebuild the devastated towns along the coast.
However, Japan is still dealing with the economic and political fallout of the disaster. Japan’s prime minister at the time of the disaster, Naoto Kan, resigned months later.
Naoto Kan had been criticized for failing to show leadership during the nuclear crisis after the quake. The nuclear crisis also revealed serious flaws in the nuclear industry’s regulatory systems and safety standards.
Although much of the debris has been cleared, survivors from the devastated north-east have complained about slow recovery efforts.