TOKYO: A moderate 5.6-magnitude quake rattled Japan's southern Ryukyu islands Tuesday, US seismologists said, but there was no immediate tsunami warning nor reports of damage.
The quake struck at 4:31 am (1931 GMT Monday) 83 kilometres (52 miles) southwest of the city of Naha, the United States Geological Survey said.
It struck at a relatively shallow depth of 18 kilometres.
Japan, located at the junction of four tectonic plates, experiences 20 percent of the strongest quakes recorded on Earth each year.
A 9.0-magnitude earthquake in March 2011 triggered a monster tsunami that killed more than 19,000 people and crippled the cooling systems at Japan's Fukushima nuclear plant, causing meltdowns in some of its reactors. (AFP)