RVO reported that dark gray ash plumes were occasionally emitted from Manam's Southern Crater during 8-12 January. At about 1000 on 12 January a sub-Plinian eruption generated ash plumes that rose 1.4-1.5 km above the crater; activity peaked between 1200 and 1300. The ash plumes drifted SW, S, and SE, producing ashfall on the island in areas downwind and light ashfall in Bogia (23 km SSW). Rumbling was heard in areas on the S and SW parts of the island, and a few loud booming noises were heard in Bogia. Activity decreased after 1600 and ash plumes only rose 500 m above the crater. At night ejected incandescent material was observed. Ejected material and ashfall was deposited in the SE and SW valleys. Ash plumes drifted S during 13-14 January. White vapor plumes rose from Main Crater during the reporting period.

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: Rabaul Volcano Observatory (RVO)