An earthquake of 6.5 magnitude struck off the south coast of Papua New Guinea on Monday, the US Geological Survey (USGS) said. There was no Pacific-wide tsunami threat from the quake that struck east of Lae, just off the southern coast of the PNG island of New Britain, the Pacific Tsunami Warning Centre said. New Britain, the largest island of the Bismarck Archipelago, is east of mainland New Guinea and has a population of around 500,000 people. It lies on the 4,000-kilometre Pacific-Australia plate, which forms part of the "Ring of Fire, a hotspot for seismic activity due to friction between tectonic plates.