Report on Manam (Papua New Guinea) — 15 December-21 December 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 15 December-21 December 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Manam (Papua New Guinea). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 15 December-21 December 2004. 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)
Based on information from RVO, the Darwin VAAC reported that the Alert Level at Manam was raised from 2 to 3 on 19 December. During 19-20 December, satellite imagery showed that ash plumes rose to at least 9 km a.s.l. and ash high as 15 km a.s.l. and drifted ~460 km WSW of Manam. Clouds dissipated by 20 December at 1230.
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.