Strong earthquake jolts southern Japan, no tsunami warning

A strong earthquake shook southern Japan on Tuesday but no tsunami warning was issued and there were no immediate reports of injuries or damage.

The quake, with a preliminary magnitude of 6.4, struck at 0532 IST and was centered off Okinawa Island, the Japan Meteorological Agency said.

Okinawa is about 1,600 kilometres southwest of Tokyo.

Japan is one of the world's most earthquake-prone countries and sits atop four tectonic plates.