RVO reported mild activity from Manam's Southern Crater during the first two weeks of May. Emissions consisted of diffuse white vapor, with diffuse blue plumes observed during 5-6 and 13-14 May. Gray and gray-brown ash clouds rose from the crater on 7, 9, and 12 May. Incandescence was visible at night during 6, 8, 10-11, and 13-14 May, and incandescent tephra was occasionally ejected from the crater.

Activity increased on 16 May, marked by a change in emissions from gray and gray-brown ash clouds to gray-to-black ash clouds, and an increase in ejected incandescent tephra. On 27 and 30 May Strombolian activity was observed, and for periods lasting 1-2 hours incandescent tephra was continuously ejected from the crater. On 30 May two vents in Southern Crater produced lava fountains. Rumbling was heard, and ash plumes rose 100-400 m above the crater and drifted NW. Most of the ejected tephra fell back into the crater but some was channeled into the SE and SW valleys. Emissions from Main Crater were milder and mostly characterized by white plumes. Gray-to-gray-brown ash plumes were noted during 6, 10-11, 13, 26, 28-29, and 31 May. Fluctuating incandescence was intermittently observed. Ash fell in the NW part of the island.

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)