The quake was centered near Okinawa's main island, the Japan Meteorological Agency said on its Web site. The quake's depth is ``very shallow'' and ``minor changes in sea level are possible,'' the agency said. No tsunami warning has been issued.
The country's last major earthquake hit the north-central prefecture of Niigata on July 16, killing 11 people and injuring more than 1,000. Damage from the magnitude 6.8 quake forced Tokyo Electric Power Co. to close its biggest nuclear power plant and Japanese carmakers, including Toyota Motor Corp., to cut production after a parts supplier in the region halted operations.
A quake that hit the same area in 2004 killed 33 people, shut a section of a bullet train line and halted production at a semiconductor plant operated by Sanyo Electric Co.