A powerful earthquake rocked northern Japan early on Tuesday, November 22, briefly disrupting cooling functions at a nuclear plant and generating a small tsunami that hit the same Fukushima region devastated by a 2011 quake, tsunami and nuclear disaster, Reuters reports.
The magnitude 7.4 earthquake, which was felt in Tokyo, sent thousands of residents fleeing for higher ground as dawn broke along the northeastern coast.
There were no reports of deaths or serious injuries several hours after the quake hit at 5:59 a.m. (2059 GMT Monday). It was centered off the coast of Fukushima prefecture at a depth of about 10 kilometers (6 miles), the Japan Meteorological Agency (JMA) said.
A wave of up to 1.4 meters (4.5 ft) high was recorded at Sendai, about 70 km (45 miles) north of Fukushima, with smaller waves hitting ports elsewhere along the coast, public broadcaster NHK said.
Television footage showed ships moving out to sea from harbors as tsunami warnings wailed after alerts of waves of up to 3 meters were issued.
“We saw high waves but nothing that went over the tidal barriers,” a man in the city of Iwaki told NTV television network.
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, Reuters reports.
All Japan’s nuclear power plants on the coast threatened by the tsunami have been shut down in the wake of the March 2011 disaster, which knocked out cooling systems at Tokyo Electric Power Co’s Fukushima Daiichi nuclear plant, causing reactors to melt down and spew radiation into the air, soil 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.
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.