Here's the report from the Earthquake News Site:

M7.3 quake hits Okinawan islands
TOKYO, Dec. 18, Kyodo -
A strong earthquake with a preliminary magnitude of 7.3 on the Richter scale hit the Okinawan islands at 1:02 p.m. on Tuesday, the Japan Meteorological Agency said.

The quake hit Yonagunijima, Ishigakijima and Taramajima islands in the island prefecture. There were no immediate reports of casualties or damage from the quake, but the agency has issued a tidal wave warning.

The quake registered 4 on the Japanese intensity scale of 1 to 7 in Yonagunijima and 3 in Ishigakijima and Taramajima, it said.

The agency said tidal waves of up to 0.5 meter are expected, with tidal waves already believed to have reached some areas.

The quake was of about the same magnitude as the 1995 Great Hanshin Earthquake which killed over 6,400 people.