SYDNEY: A 6.4-magnitude earthquake struck off Papua New Guinea on Thursday, officials said, but no Pacific-wide tsunami warning was issued. The tremor hit at a depth of 46 kilometres (28 miles) near the sparsely-populated New Ireland region, 110 kilometres southeast of the town Kokopo, the United States Geological Survey said. The Hawaii-based Pacific Tsunami Warning Center ruled out a widespread tsunami and Geoscience Australia estimated any damage would only be within a 49-kilometre radius. Earthquakes are common near Papua New Guinea, which lies on the 4,000-kilometre-long Pacific Australia plate. It forms part of the “Ring of Fire”, a hotspot for seismic activity due to friction between tectonic plates.