Report on Manam (Papua New Guinea) — 25 August-31 August 2010
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 August-31 August 2010
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2010. Report on Manam (Papua New Guinea). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 August-31 August 2010. Smithsonian Institution and US Geological Survey.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
RVO reported that during 13-26 August incandescence from Manam's South Crater was visible at night. Main Crater emitted diffuse white vapor. During 27-28 August incandescence emanated from both craters and brightened every 15-20 minutes. At that time, incandescent lava fragments ejected tens to hundreds of meters above South Crater were reported from observers in Bogia, about 23 km SSW. Weak explosions were heard at 15-20 minute intervals. During 28-29 August diffuse white-to-blue vapor emissions from Main Crater were occasionally accompanied by diffuse gray ash plumes. Incandescent lava fragments continued to be ejected. Based on analysis of satellite imagery, the Darwin VAAC reported that on 30 August an ash plume rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 55 km NW.
Geologic Background. 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 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche 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 historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent historical 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: Darwin Volcanic Ash Advisory Centre (VAAC), Rabaul Volcano Observatory (RVO)