RVO reported that variable low-level activity continued to be detected at Manam's Southern Crater during 16-30 September. White and occasionally gray ash plumes rose from the crater during 16-24 September, and gray ash clouds were observed during 25-29 September. Only white plumes rose from the crater on 30 September. Ash clouds drifted NW, producing ashfall in the NW part of the island. Two vents in the SE valley, just below the summit crater, produced small-volume lava flows, channeled into the deep ravines on the upper slopes of the SE valley. Glow from the crater was visible on most nights. Incandescent lava fragments were ejected from the crater during 16-17, 19-20, and 24-28 September. The ejections were occasionally sub-continuous to fountaining. Roaring and rumbling noises were sometimes heard at the Bogia station on the mainland on 16, 21, and 26 September. White vapor plumes rose from Main Crater during the reporting period.

According to the Darwin VAAC a pilot reported an intermittent eruption with a diffuse ash plume on 8 October. During 8-9 October satellite imagery showed a thermal anomaly, and an ash plume that rose to an altitude of 3.4 km (11,000 ft) a.s.l. and drifted about 45 km ENE.

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)