Report on Manam (Papua New Guinea) — December 1983
Scientific Event Alert Network Bulletin, vol. 8, no. 12 (December 1983)
Managing Editor: Lindsay McClelland.
Manam (Papua New Guinea) Glow, tephra ejection, explosions at summit craters
Please cite this report as:
Global Volcanism Program, 1983. Report on Manam (Papua New Guinea) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 8:12. Smithsonian Institution.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
"The moderate level of activity from Main crater reported in November decreased early in December. After a comparative lull 3-13 December, vapour emission from Southern crater increased, and from the 17th onwards night glow and ejection of incandescent fragments were observed. Glow from Main crater was also observed from 18 December onwards. The combined activity was accompanied by deep rumblings, explosion noises, and the discharge of a moderately large, strongly coloured, ash-laden vapour plume. Light ashfalls were experienced daily on the SW side of the island for the remainder of the month."
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.
Information Contacts: P. Lowenstein, RVO.