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The quake hit at 10:56 am (0156 GMT) 107 kilometres (66 miles) southeast of the capital beneath the Pacific Ocean, some 35.6 kilometres deep, USGS said.The Japan Meteorological Agency, which measured the quake at 5.2, said there was "no tsunami threat".
Around 20 percent of the world's most powerful earthquakes strike Japan, which sits on the "Ring of Fire" surrounding the Pacific Ocean.Tectonics experts have warned of a 70 percent chance that the "Big One" -- a magnitude-seven earthquake or worse -- will strike the greater Tokyo region, home to around 35 million people, within the next 30 years.