A strong earthquake with a preliminary magnitude of 5.9 jolted an island in southern Japan on Thursday afternoon, but there were no immediate reports of damage or injuries. The quake was centred about 30 miles under the seabed near Miyakojima, an island 1,150 miles, southwest of Tokyo, the Meteorological Agency is quoted by Associated Press as saying. Police said no damage or injuries were reported from the 2:41 p.m. tremor. The island has a population of about 50,000. A tremor of magnitude 5 can damage homes. There was no fear of tsunami, or seismic waves caused by undersea disturbances such as volcanic activities or undersea earthquakes, the agency said. Separately, a magnitude 4.7 earthquake shook parts southwestern Japan about 320 miles southwest of Tokyo. That quake was centred about 12 miles underground in the southern part of Tokushima state and struck at 2:12 p.m. Police reported no damage or injuries. The agency said the two quakes were not related. Japan is one of the world's most earthquake-prone countries as it sits atop four tectonic plates, slabs of land that move across the earth's surface.