Report on Manam (Papua New Guinea) — December 1991
Bulletin of the Global Volcanism Network, vol. 16, no. 12 (December 1991)
Managing Editor: Lindsay McClelland.
Manam (Papua New Guinea) Ash emission; incandescent lava fragments roll down flank valley
Please cite this report as:
Global Volcanism Program, 1991. Report on Manam (Papua New Guinea) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 16:12. Smithsonian Institution.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
"Activity . . . remained at a low level. Main Crater was inactive throughout December except for a very weak emission of white vapour on the 23rd. Southern Crater activity consisted mostly of weak white vapour emissions. A forceful ejection produced a thick, dark ash cloud that rose several hundred meters above the summit on 5 December from 1105 to 1120, accompanied by intermittent roaring and rumbling noises. Incandescent lava fragments were observed rolling down the SW valley, and there was light ashfall on the NW and SW sides of the island. Light ashfalls also occurred on 20 and 26 December. No night glow was visible above the summit during the month. The seismograph was not operational."
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: D. Lolok and B. Talai, RVO.