Karkar volcano along with its neighbor Manam is one of Papua New Guinea's most active volcanoes. The volcano is located on Karkar Island off New Guinea's north coast 64 km north of Madang.
The forested Karkar Island is 25 km long and 19 km wide and cut by 2 nested summit calderas. The 5.5-km-wide outer caldera was formed during one or more eruptions, the last of which occurred 9000 years ago. The inner caldera is almost circular in shape and has 3.2 km in diameter with vertical walls up to 300 m high. It was formed during violent eruptions sometime between 1500 and 800 years ago.
The historic activity at Karkar volcano, recorded since 1643, consisted in small explosions including strombolian and phreatic eruptions. Most eruptions came from Bagiai vent, a cinder cone inside the inner caldera.