NHK said the Japan Meteorological Agency had issued a tsunami warning, one notch lower than a tsunami alert, for the Pacific coast of Iwate, Fukushima, Aomori and Ibaraki prefectures.
There was no threat of a Pacific-wide tsunami, US monitors based in Hawaii said. Officials in both Indonesia and the Philippines south of Japan said there was no threat of a localised tsunami.
Nuclear plant operator Tokyo Electric Power told AFP there were no reports of any problems at the crippled Fukushima nuclear plant.
“No abnormalities have been recorded on instruments at Fukushima Daiichi nuclear plant’s six reactors,” a TEPCO spokesman said.
“All workers were ordered to take shelter inside buildings at the Fukushima plant.
“No abnormalities were confirmed with the radiation monitoring posts at the Fukushima plant. No abnormalities were seen with the water processing facilities.”
Prime Minister Yoshihiko Noda was heading to his office where he would be monitoring the situation, Jiji Press said.
Japan Railways East temporarily suspended Shinkansen bullet train services to check any damage, Jiji said, while Haneda Airport near central Tokyo was reported to be operating normally.
Narita airport was reported to have resumed operations after a temporary suspension.