Based on information from RVO, the Darwin VAAC reported that the Alert Level at Manam was raised from 2 to 3 on 19 December. During 19-20 December, satellite imagery showed that ash plumes rose to at least 9 km a.s.l. and ash high as 15 km a.s.l. and drifted ~460 km WSW of Manam. Clouds dissipated by 20 December at 1230.

Geological Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical basaltic-andesitic stratovolcano to its lower flanks. These valleys channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most observed eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)