A magnitude-7.1 earthquake struck early on Saturday off the coast of north-eastern Japan, prompting authorities to urge residents to evacuate prefectures and issue a tsunami warning.
The tremor occurred at 2:10 am (17:10 Friday GMT) and its epicentre was located off Fukushima prefecture at a depth of 10 kilometres, the Japan Meteorological Agency said.
The quake prompted the agency to issue tsunami warning and thousands of residents were urged to evacuate in the prefectures of Iwate and Miyagi. Tsunami waves of up to 0.4 metres were observed on the coast of north-eastern Japan after the quake, the agency said.
There were no reports of casualties or damage, and no abnormalities were detected at the damaged Fukushima Daiichi Nuclear Power Station, where three nuclear reactors suffered meltdowns after a tsunami swept through the plant in March 2011.
The Pacific Tsunami Warning Center in the United States said it did not expect a destructive Pacific-wide tsunami.
“Based on all available data a destructive Pacific-wide tsunami is not expected and there is no tsunami threat to Hawaii,” it said in a statement on its website.
The US Geological Survey measured the quake at magnitude 7.3 in the Pacific Ocean about 300 kilometres from Fukushima’s coast. The agency later reported an aftershock with a magnitude of 5.5 occurred more than 300 kilometres east of Iwaki at a depth of nearly 2 kilometres.