A powerful magnitude-7.5 earthquake has hit Papua New Guinea, with unconfirmed reports of blackouts and damage to buildings.

According to the US Geological Survey, the quake's epicentre was around 90 kilometres south of Porgera in Enga province and hit at a depth of 35 kilometres. The quake hit PNG's mountainous interior and US authorities said there is no tsunami threat. The USGS said some casualties and damage are possible. Recent earthquakes in the area have caused landslides, but the impact should be relatively localised. Earthquakes are common in PNG, which sits on the so-called Pacific Ring of Fire, a hotspot for seismic activity due to friction between tectonic plates.