Report on Manam (Papua New Guinea) — July 1982
Scientific Event Alert Network Bulletin, vol. 7, no. 7 (July 1982)
Managing Editor: Lindsay McClelland..
Manam (Papua New Guinea) Ash emission; weak seismicity; minor deflation
Please cite this report as:
Global Volcanism Program, 1982. Report on Manam (Papua New Guinea). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 7:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198207-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
"Fairly steady levels of activity prevailed at both craters in June and July. Southern crater has released moderate volumes of grey-brown ash-laden emissions and occasionally blue vapours. Rumbling and roaring sounds accompanying these emissions indicated a relatively mild eruptive condition. No glows from this crater were seen in June or July.
"Main crater emitted grey to dark grey and rarely brown ash clouds in usually moderate volumes, also accompanied by roaring and rumbling sounds. Crater glows were seen on 18 June and 17 July. Light ashfalls in coastal areas (about 5 km from the craters) were reported on 28 June and 14, 15, 17, 18, and 24 July. A persistent blue vapour haze on the upper flanks of the volcano was observed on 19 and 24 June and 6, 11, and 30 July.
"Seismic activity was remarkably steady in June and July at a low level. The tiltmeters at Tabele Observatory on the SW side of Manam have registered 3-4 µrad of northerly down-tilt since early March."
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.