Tsunami warning lifted after earthquake hits near Fukushima

Tsunami warnings have been lifted after an earthquake rocked northern Japan early on Tuesday, briefly disrupting cooling functions at a nuclear plant.

The magnitude 7.4 earthquake off Fukushima Prefecture has stirred unwelcome memories of Japan's deadly 2011 disaster, triggering tsunami fears and sending thousands of people fleeing to higher ground.

The earthquake struck under the sea off the coast of Fukushima just before 6am on Tuesday morning (9pm on Monday Irish time). Japan’s Meteorological Agency said it was an aftershock of the huge quake that had pummelled the same area in March 2011.

The US Geological Survey measured Tuesday’s quake at magnitude 6.9, down from 7.3. Japanese authorities have not updated their initial measurement of 7.4.

Buildings in the capital Tokyo, about 240km from the epicentre, swayed and shook for about 30 seconds, waking the city's residents and sending the government into emergency mode.

Authorities issued an immediate warning for a tsunami of 3m, along with evacuation orders to hundreds of thousands of people. About two hours later, the highest wave of 1.4m was recorded in Sendai, Miyagi Prefecture, north of Fukushima.

The 2011 quake and tsunami killed about 18,000 people, left many more homeless and caused the meltdown of three of the six reactors at the Fukushima Daiichi Nuclear Power Plant.

A spokesperson for the plant operator, Tokyo Electric Power Co. (TEPCO) said “no abnormalities” had been detected there following Tuesday’s quake, but an onsite system for treating contaminated water had been “manually suspended.”

Engineers use water at the plant to keep melted fuel from the 2011 meltdowns from overheating, a process that generates thousands of gallons of contaminated water every day.

The TEPCO spokesperson said the cooling system for a spent fuel pool at the nearby Daini plant, about 10km away, had shut down for over an hour before resuming at 7:47am local time.

All tsunami warnings were lifted by Tuesday afternoon, but local people have been told that another strong quake could rattle the area in the next few days.

An early wobble in Japan’s stock markets, as investors digested the news from the north-east, was quickly reversed when television pictures confirmed that the damage was not serious.

Alerted about the quake in Buenos Aires, where he is returning from a summit, Japanese prime minister Shinzo Abe said he had ordered his government to “do everything possible to tackle the disaster”.

Jun Matsumoto, minister of state for disaster management, said there have been no reports of serious injuries or damage from the quake.

Media reports say a fire broke out at a petrochemical plant in Iwaki city, in southern Fukushima Prefecture. At least eight people were hurt, mainly from falling objects in their homes. Several boats were overturned at sea.

Suspended train services in the area were quickly restarted.

About 10,000 people along the northwest coast took the tsunami warning seriously and fled their homes, according to Kyodo News agency. Hundreds of people were killed in 2011 after ignoring similar warnings.

Interviewed on NHK, Japan’s public service broadcaster, local people said they had grabbed their children and driven to schools and evacuation centres. “All I could think of is what happened five years ago,” said one woman. “I didn’t want to take any chances.”