Strong quake hits Japan's Ishigaki Island

TOKYO, Aug. 17 (Xinhua) -- A strong earthquake with a preliminary magnitude of 6.8 rocked Ishigaki Island in Japan's southernmost Okinawa Prefecture on Monday, said the Japan Meteorological Agency, which issued a tsunami alert.

The focus of the quake, which occurred at 9:06 a.m. (0006 GMT), was located some 10 km under the sea off Ishigaki Island, said the agency.

There were no immediate reports of casualties or damage to properties.