Report on Manam (Papua New Guinea) — September 1981
Scientific Event Alert Network Bulletin, vol. 6, no. 9 (September 1981)
Managing Editor: Lindsay McClelland.
Manam (Papua New Guinea) Incandescent tephra ejected; ash emission and seismicity decline
Please cite this report as:
Global Volcanism Program, 1981. Report on Manam (Papua New Guinea). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 6:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198109-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
"There were fewer instances of ash emission from both craters in September. Usually, Southern crater released moderate volumes of thick white vapour. However, rumbling sounds from the volcano were common, and weak glow and ejections of incandescent lava fragments from Southern crater were observed on 15 September. No trends were evident from tiltmeter measurements. Seismicity remained at a level higher than normal for most of the month, but declined near the end of the month to levels prevailing in the first half of 1981."
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: C. McKee, RVO.