JAKARTA, Indonesia — A magnitude-6.5 undersea earthquake shook the western shore of Indonesia's Sumatra island on Friday, causing panic but no casualties or damage, an official said. The quake struck late at night 74 miles (119 kilometers) southeast of Pagai Selatan, an island off the western coast of Sumatra, Indonesian Meteorology and Geophysics Agency official Gian Ginanjar said. The quake struck 6 miles (10 kilometers) beneath the Indian Ocean bed.