The epicentre of the tremor was 36 kilometres under the Pacific seabed, 115km from Ishigaki-jima in the Ryukyu islands far to the southwest of mainland Japan, according to the US Geological Survey.
The Japan Meteorological Agency issued a tsunami warning following the quake and warned residents in the Miyakojima and Yaeyama areas to beware.
Japan, which sits on the ‘Ring of Fire’ surrounding the Pacific Ocean, is prone to earthquakes but high building standards and regular drills mean that casualties are often minimal.