The Darwin VAAC reported that a large thermal anomaly over Manam was identified in satellite images during 21-22 December. A discrete ash plume rose to 3.4 km (11,000 ft) a.s.l. and drifted SE on 21 December. Ash plumes may have risen to 10.7 km (35,000 ft) a.s.l. during 0137-0300 on 22 December, though weather clouds and heavy rain obscured satellite views; the plumes were unconfirmed by ground observers. At 1200 on 22 December an ash plume rose to 4.9 km (16,000 ft) a.s.l., drifted E, and dissipated within four hours.

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)