TOKYO -- An earthquake with a preliminary magnitude of 5.7 struck off Iriomote Island, southwestern Japan at 10:42 pm local time (1345 GMT), Japan Meteorological Agency (JMA) said Thursday.The temblor was centered in the waters near Iriomote Island, southwestern Japan with the epicenter at a latitude of 24.2 degrees north and a longitude of 123.8 degrees east and at depth of 20 km.The earthquake logged lower 5 in some parts of Okinawa prefecture on the Japanese seismic intensity scale which peaks at 7.So far no major damage or injuries were reported, and no tsunami warning has been issued.