A 7.5-magnitude earthquake shook Papua New Guinea Tuesday and scientists issued a local tsunami alert, dpa reported. The epicentre was offshore about 133 kilometres south of Kokopo on the island of New Britain, the US Geological Survey reported. The Pacific Tsunami Warning Centre said hazardous waves were forecast for some coasts within a 300-kilometre radius. Two quakes last week hit in the same general region, but caused no damage.