The volcano on Manam Island, in Papua New Guinea's Madang province, erupted on Sunday, forcing residents who'd returned to flee again.
Manam is one of PNG's most active volcanoes, which last erupted in August 2015.
A local councillor, Paul Maburau, said the volcano began belching smoke and flames at about 7 o'clock on Sunday night.
He told the newspaper, The National, that blasts have continued until Tuesday and the island is very dark.
Mr Maburau said residents had taken refuge, with many choosing to leave the island on dinghies to nearby Bogia, on the mainland.
The provincial disaster office said it was aware of the eruption and was planning to assess the situation and help those on the island.