An earthquake with a preliminary magnitude of 7.3 hit northern Japan on Tuesday, the Japan Meteorological Agency said, generating a tsunami that hit the nation’s northern Pacific coast.
The U.S. Geological Survey initially put Tuesday’s quake at a magnitude of 7.3 but down graded it to 6.9.
The earthquake, which was felt in Tokyo, was centered off the coast of Fukushima prefecture at a depth of about 10 km (6 miles) and struck at 5:59 a.m. (2059 GMT) the agency said.
USGS said that it was a shallow quake, at about 10 kilometers, which tended to cause more shaking damage and had greater potential to cause a tsunami.
“The good news here is that the direction the fault was moving is a slight lateral slip. When the faults move laterally they do not create the vertical movement associated with large tsunamis,” the U.S. agency said.
A 60 cm (2 foot) tsunami had been observed at Iwaki city’s Onahama Port and a 90 cm (3 foot) tsunami at Soma Port soon after, public broadcaster NHK said. The region is the same that was devastated by a tsunami following a massive earthquake in 2011. A tsunami warning of up to 3 meters (10 feet) has been issued.
Japan’s chief government spokesman Yoshihide Suga said that a government taskforce had been established to deal with the quake and tsunami, and called on people in affected areas to evacuate, according to media outlet NHK.
NHK also reported that water could be seen moving bath and forth in Onahama Port and that tide levels were rising in some areas on Japan’s eastern coast. Television footage showed ships moving out to sea from Fukushima harbors as tsunami warning signals wailed.
Tokyo Electric Power, known as Tepco, said on its website that no damage from the quake has been confirmed at any of its power plants, although there have been blackouts in some areas. Tepco’s Fukushima Daiichi nuclear plant caused Japan’s worst nuclear disaster when it was knocked out by the 2011 tsunami.
Tohoku Electric Power 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.
Earthquakes are common in Japan, one of the world’s most seismically active areas. Japan accounts for about 20 percent 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 world’s worst nuclear crisis since Chernobyl a quarter of a century earlier.
An Iwaki city fire dept official said there was smoke or fire at Kureha’s research center in a petrochemical complex in Iwaki city at 6:17 a.m., but it was extinguished at 6:40 a.m. Other details were not clear, he said, adding that no other major damage in the city has been reported at the moment.
One hotel in Ofunato, badly hit by the 2011 quake, told guests to stay in the facility, which is on high ground.
All nuclear plants on the coast threatened by the tsunami are shut down in the wake of the 2011 Fukushima disaster. Only two reactors are operating in Japan, both in the southwest of the country. Even when in shutdown nuclear plants need cooling systems operating to keep spent fuel cool.
At Fukushima Daiichi, the plant workers are reporting they felt shaken even in the seismic isolation building. Most of the workers have not come to the plant for today yet. The situation is still under investigation. No further information yet.
At Fukushima Daini, Tepco said that its water-cooling system for spent fuel at reactor 3 had stopped working at 6:10AM but that there was enough water in the pool to keep the fuel cool, posing no immediate danger. Tepco rebooted the coolant system of SFP 3 of Fukushima DAINI at 7:47AM (JST).