Japan hit by earthquake considered an aftershock of 2011 Fukushima disaster

A powerful earthquake rocked northern Japan on Tuesday, briefly disrupting cooling functions at a nuclear plant and generating a tsunami that hit the same region devastated by a massive quake, tsunami and nuclear disaster in 2011.

Expanded alert system, including warnings not in Japanese, executed after grave quake 5 years ago

In this image captured from video released by the local police there, water flows up the Sunaoshi River in Tagajo, Miyagi prefecture, northern Japan, as a tsunami warning was issued for a time following a strong earthquake early Tuesday. (Miyagi Prefectural Police/Kyodo News via AP)

A powerful earthquake rocked northern Japan on Tuesday, briefly disrupting cooling functions at a nuclear plant and generating a tsunami that hit the same region devastated by a massive quake, tsunami and nuclear disaster in 2011.

There were no reports of deaths or serious injuries several hours after the 7.4 quake hit at 5:59 a.m. local time. It was centred off the coast of Fukushima prefecture at a depth of about 10 kilometres, the Japan Meteorological Agency (JMA) said.

The magnitude earthquake was felt in Tokyo, said CBC reporter Adam Walsh, and it sent thousands of residents fleeing for higher ground as dawn broke along the northeastern coast.

A wave of up to 1.4 metres high was recorded at Sendai, about 70 km north of Fukushima, with smaller waves hitting ports elsewhere along the coast, public broadcaster NHK said.

A magnitude of 7.4 earthquake hit northern Japan on Tuesday, (Natalie Holdway/CBC)

The JMA later said the quake was an aftershock of the magnitude 9.0 earthquake that spawned a deadly tsunami in the same region in 2011. The agency warned that another large quake could hit in the next few days and urged residents to remain cautious for about a week.

Television footage showed ships moving out to sea from harbours as tsunami warning signals wailed, after warnings of waves of up to three metres were issued.

"We brought the ships out to sea because of the tsunami, because we did the same thing during the last tsunami," an unidentified woman told NHK near the port of Onahama.

No major damage reported at nuclear plants

Aerial footage showed tsunami waves flowing up rivers in some areas, and some fishing boats were overturned in the port of Higashi-Matsushima.

The Pacific Tsunami Warning Center in Hawaii said the tsunami threat had now largely passed and the JMA later lifted its warnings.

The U.S. Geological Survey measured Tuesday's quake at magnitude 6.9, down from an initial 7.3.

All Japan's nuclear power plants on the coast threatened by the tsunami are shut down in the wake of the March 2011 disaster, which knocked out Tokyo Electric Power Co's Fukushima Daiichi nuclear plant, spilling radiation into the air and sea.

The cooling system for a storage pool for spent nuclear fuel at the reactor at its Fukushima Daini Plant was initially halted on Tuesday, said a spokeswoman for Tokyo Electric Power, known as Tepco, but was restarted soon after.

People keep a lookout at the mouth of a river after tsunami advisories triggered by an earthquake were issued, in Iwaki, Fukushima prefecture, Japan. (Kyodo via Reuters)

No other damage from the quake has been confirmed at any of its power plants, although there have been blackouts in some areas, the spokeswoman said.

Only two reactors are operating in Japan, both in the southwest. Even when in shutdown, nuclear plants need cooling systems operating to keep spent fuel cool.

Tohoku Electric Power Co said there was no damage to its Onagawa nuclear plant, while the Kyodo news agency reported there were no irregularities at the Tokai Daini nuclear plant in Ibaraki prefecture.

2011 lessons 'really taken to heart'

One woman suffered cuts to her head from falling dishes, Kyodo news agency reported, citing fire department officials.

Japanese Minister for Disaster Management Jun Matsumoto told reporters about three hours after the quake that there had been no reports of significant injuries so far.

A traffic jam is seen as people evacuate after tsunami advisories were issued following an earthquake in Iwaki. (Kyodo via Reuters)

NHK showed footage of residents of Ishinomaki, a city badly hit in 2011, standing on a hill dressed in hats and heavy coats, staring down at the ocean.

Several thousand people along the coast evacuated or were told to evacuate.

Earthquakes are common in Japan, one of the world's most seismically active areas. Japan accounts for about 20 per cent of the world's earthquakes of magnitude 6 or greater.

The March 11, 2011, quake was magnitude 9, the strongest quake in Japan on record. The massive tsunami it triggered caused the world's worst nuclear crisis since Chornobyl a quarter of a century earlier.

Because of the lessons learned from the disaster five years ago, announcers on Tuesday abandoned their usual careful modulation for an unsettling note of urgency, repeatedly telling listeners, "Do not go near the water, a tsunami is coming!" as messages flashed on the screen in red saying "Tsunami! Run!"

And in a nod to a growing number of foreign residents, a dubbed version of the NHK channel broadcast warnings in English, Chinese and Korean. Several young foreign English teachers died in 2011, prompting speculation they had not known of the danger.

Staying in a traditional Japanese inn on the coast in the city of Ofunato with a dozen international high school students on a study tour, teacher Kathy Krauth said the shaking began just seconds after a quake alarm on her phone went off.

"I felt like the lessons of 3-11 were really taken to heart," said Krauth, who teaches a class on the March 2011 disaster and its aftermath. "The feeling was, we just don't know, but we're going to be as cautious as we can."

Passengers crowd at Sendai Station in Sendai, Miyagi prefecture, northern Japan Tuesday, Nov. 22, 2016 after train services are suspended following an earthquake. (Jun Hirata/Kyodo News via Associated Press)

Nissan Motor Co said it would suspend work at its engine factory in Fukushima at least until the tsunami warning was lifted. A spokesman said there were no injuries or damage at the plant, which was badly damaged in the 2011 disaster. 

Separately, Toyota Motor Corp said all its factories in northeastern Japan were operating as usual. An Iwaki city fire department official said there was smoke or fire at Kureha's research centre in a petrochemical complex in Iwaki city at 6:17 a.m. but it was extinguished soon after.

Japan's famous Shinkansen bullet trains were halted along one stretch of track and some other train lines were also stopped. 

One hotel in Ofunato, also badly hit by the 2011 quake, initially told guests to stay in the facility but later bussed them to higher ground.

Japanese financial markets were little affected, with the Nikkei 225 index closing up 0.3 per cent and the yen steady against the U.S. dollar.

With files from The Associated Press