Report on Manam (Papua New Guinea) — August 1986
Scientific Event Alert Network Bulletin, vol. 11, no. 8 (August 1986)
Managing Editor: Lindsay McClelland.
Manam (Papua New Guinea) South Crater ash emission; small low-frequency earthquakes
Please cite this report as:
Global Volcanism Program, 1986. Report on Manam (Papua New Guinea). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 11:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198608-251020.
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 throughout August. Main Crater released weak white vapour emissions, while noiseless brown ash-laden emissions rose at intervals of a few minutes from Southern Crater. These resulted in very light ashfalls on the downwind side of the volcano on most days. Deep roaring noises were occasionally reported. Seismicity remained at an inter-eruptive level, ~1,200 low-frequency small-amplitude events/day. No significant change was recorded by the Tabele water tube tiltmeters."
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. de Saint-Ours and C. McKee, RVO.