RVO reported that during 19-20 November white and blue vapor rose from Manam. Activity increased at 1200 on 20 November characterized by occasional emissions of dark grey ash. Ejected incandescent tephra was observed at night. At 1700 on 21 November a small pyroclastic flow traveled down the upper part of the SW valley. Stronger activity was detected two hours later which lasted until the next morning; incandescent tephra was ejected several hundred meters above the crater, roaring was heard in Bogia (23 km SSW), and a lava flow was extruded into the SE valley from a new vent beneath Southern Crater. The activity slightly decreased at 1700 on 22 November and diffuse ash plumes occasionally rose from the crater. Activity increased again on 24 November. Ash fell on the NW side of the island.

Based on observations of satellite imagery and reports from RVO, the Darwin VAAC reported that an ash plume rose to an altitude of 3.3 km (11,000 ft) a.s.l. on 26 November and drifted 110 km E.

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.

Sources: Rabaul Volcano Observatory (RVO), Darwin Volcanic Ash Advisory Centre (VAAC)