Report on Manam (Papua New Guinea) — September 1987
Scientific Event Alert Network Bulletin, vol. 12, no. 9 (September 1987)
Managing Editor: Lindsay McClelland.
Manam (Papua New Guinea) Minor ash emission; night glow from summit
Please cite this report as:
Global Volcanism Program, 1987. Report on Manam (Papua New Guinea). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 12:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198709-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
A low level of activity continued during September. Glow from Main Crater, frequently observed during the latter half of August, was observed only a few times in September. Main and Southern Craters weakly emitted white vapour. During the first half of the month, the emissions from both craters also contained small amounts of gray ash. No noises were heard during the month.
During September, the water-tube tiltmeter appeared to show an increased rate of change, after remaining fairly steady during July and August. A few microradians of inflationary tilt accumulated during the month. Seismic amplitudes remained at low levels, similar to August.
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: J. Mori, C. McKee, and P. Lowenstein, RVO.