The Japan Meteorological Agency had issued a tsunami warning for waves of up to 3 meters (10 feet) in Fukushima and another prefecture, and a tsunami advisory for much of the rest of northeast Japan's Pacific coast. There were no immediate reports of damage or injury.
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Tsunamis of up to 90 centimeters (3 feet) were recorded about an hour after the 6 a.m. earthquake.
Fukushima prefecture is home to the nuclear power plant that was destroyed by a huge tsunami following an offshore earthquake in 2011.
The operator of the Fukushima Dai-ichi plant said there were no abnormalities observed at the plant, though a swelling of the tide of up to 1 meter has been detected offshore.
Plant operator TEPCO said a pump that supplies cooling water to a spent fuel pool at the nearby Fukushima Dai-ni plant stopped temporarily, but that it was working again. The Tokyo-based utility is investigating the cause.
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The U.S. Geological Survey measured the magnitude at 6.9. The earthquake shook buildings in Tokyo, 240 kilometers (150 miles) southwest of the epicenter.
The meteorological agency said the quake struck at a depth of 10 kilometers (6 miles). It revised up the magnitude from an initial reading of 7.3.
NHK urged people to evacuate immediately, reminding them of the devastating 2011 quake that killed about 18,000 people.