The quake was at a depth of 51 kilometres (32 miles) about 15 kilometres south east of the town of Saiki, at 11:27 pm (1427 GMT), the US Geological Survey said.

There were no immediate reports of injuries or damage according to public broadcaster NHK. The Japan Meteorological Agency did not issue a tsunami warning.

Japan sits at the junction of four tectonic plates and experiences a number of relatively violent quakes every year. But rigid building codes and strict enforcement mean even strong tremors often do little damage.

A massive undersea quake that hit in March 2011 sent a tsunami barrelling into Japan's northeast coast, leaving more than 18,000 people dead or missing, and sending three reactors into meltdown at the Fukushima nuclear plant.