NEW : Okinawa 's Navy cancels tsunami advisory . NEW : `` There may be slight sea level changes from now on , '' agency says . Quake centered 53 miles deep , about 6 miles east of Japan .
NEW : Japan 's Meteorological Agency cancels tsunami advisory . NEW : `` There may be slight sea level changes from now on , '' agency says . Quake centered about 6 miles deep , 53 miles east of Okinawa .