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 and later downgraded it to 6.9. But the Japan Meteorological Agency put the magnitude at 7.4.
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.
The region is the same that was devastated by a tsunami following a massive earthquake on March 11, 2011. A tsunami warning for waves of up to 3 meters (10 feet) was issued after Tuesday's quake but later lifted.
USGS said that it was a shallow earthquake, 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 was recorded at Fukushima's Onahama Port and a 90 cm (3 foot) tsunami at Soma soon after, public broadcaster NHK said.
Japan's chief government spokesman Yoshihide Suga said that a government taskforce had been established to deal with the quake and tsunami risk, and called on people in affected areas to evacuate, according to NHK.
NHK also reported 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.
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The Fukushima Daiichi nuclear plant, owned by Tokyo Electric Power (Tepco), caused Japan's worst nuclear disaster when it was knocked out by the 2011 tsunami. Tepco said on Tuesday that there was no damage to Fukushima Daiichi from the latest quake.
All nuclear plants on the coast threatened by the tsunami were shut down in the wake of the 2011 disaster. Only two reactors are operating in Japan, both in the southwest of the country. But even when shutdown, nuclear plants need cooling systems operating to keep spent fuel cool.
According to NHK, Tepco said a water-cooling system for spent fuel at one reactor at Fukushim Daini had stopped working for about 90 minutes after Tuesday's earthquake and that the temperature went up slightly, but the company was able to fix it.
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.
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.
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.
The U.S. Geological Survey initially put Tuesday's quake at a magnitude of 7.3 and later downgraded it to 6.9. But the Japan Meteorological Agency put the magnitude at 7.4.
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.
The region is the same that was devastated by a tsunami following a massive earthquake on March 11, 2011. A tsunami warning for waves of up to 3 meters (10 feet) was issued after Tuesday's quake but later lifted.
USGS said that it was a shallow earthquake, 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 was recorded at Fukushima's Onahama Port and a 90 cm (3 foot) tsunami at Soma soon after, public broadcaster NHK said.
Japan's chief government spokesman Yoshihide Suga said that a government taskforce had been established to deal with the quake and tsunami risk, and called on people in affected areas to evacuate, according to NHK.
NHK also reported 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.
Video: Click Here
The Fukushima Daiichi nuclear plant, owned by Tokyo Electric Power (Tepco), caused Japan's worst nuclear disaster when it was knocked out by the 2011 tsunami. Tepco said on Tuesday that there was no damage to Fukushima Daiichi from the latest quake.
All nuclear plants on the coast threatened by the tsunami were shut down in the wake of the 2011 disaster. Only two reactors are operating in Japan, both in the southwest of the country. But even when shutdown, nuclear plants need cooling systems operating to keep spent fuel cool.
According to NHK, Tepco said a water-cooling system for spent fuel at one reactor at Fukushim Daini had stopped working for about 90 minutes after Tuesday's earthquake and that the temperature went up slightly, but the company was able to fix it.
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.
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.
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.