The US Geological Survey says the magnitude 5.9 quake struck Saturday evening 30 kilometers (19 miles) southeast of Ohara at a depth of 39 kilometers (24 miles). The Japan Meteorological Agency put the magnitude at 6.0.
Japan's Kyodo news agency and public broadcaster NHK both reported that the runways at Narita airport, east of Tokyo, were shut down briefly after the quake but flights resumed soon after. The quake was mostly felt in the area east of Tokyo.
Japan sits on the Pacific "Ring of Fire" and is prone to earthquakes and volcanic eruptions. (AP)