Japan's meteorological agency says a strong earthquake with a preliminary magnitude of 6.0 has struck off the south coast of the southern Japanese island of Okinawa. The agency says the quake occurred at 4:42 p.m. (0742 GMT) Tuesday about 30 miles (50 kilometers) below the ocean's surface. The agency says there is no danger of a tsunami, or seismic waves, and there were no immediate reports of injuries or damage. Okinawa is about 1,000 miles (1,600 kilometers) southwest of Tokyo.