The Kadovar Island volcano was thought to be dormant before it started erupting on Friday.
Around 1500 are being evacuated from Papua New Guinea's islands as a volcano started to spew ash.
Kadovar Island, a volcanic mass on the north coast of Papua New Guinea, was previously thought to be dormant.
The 365-metre-tall phenomenon began erupting on Friday, emitting ash clouds as high as 2,133 meters.
On Friday, around 500 residents on Blup Blup Island were safely evacuated amid reports of a large explosion from the volcano.
A fiery red glow was also seen at the summit and scientists at the Rabaul Volcanological Observatory reported that a dome of lava could be seen on Kadovar.
There are fears the eruption may become explosive, bringing a risk of tsunamis and landslides, said Loop PNG citing the Rabaul Volcanological Observatory.