The Pacific island nation of Papua New Guinea was rattled by a powerful 6.8-magnitude earthquake Monday, with a minor tsunmai warning issued. The US Geological Survey said the quake occurred at a depth of 16 kilometres (10 miles), some 131 km (81 miles) east of Wewak. "No destructive widespread tsunami threat exists based on historical earthquake and tsunami data," the Pacific Tsunami Warning Centre said. "However, earthquakes of this size sometimes generate local tsunamis that can be destructive along coasts located within a hundred kilometers of the earthquake epicentre."