A Kiwi volcanologist says Vanuatu's Monaro volcano could keep erupting for months.
More than 11,000 people are being evacuated from the volcano on Ambae island, with New Zealand and Australia both sending help.
GNS scientist Brad Scott flew over the volcano on Sunday afternoon. He witnessed a range of volcanic activity, including incandescent lava flows, which he hasn't seen there before.
"Explosions were occurring every three or five seconds," he told Newshub.
"The northernmost vent in particular was the most active, and there were lava bombs being generated up to maybe 50-80 metres height, every five seconds or so."
He says the style of eruption has significantly changed.
Mr Scott will be meeting with his team to discuss the findings later on Sunday and volcanic alert levels may need to be revised.