Report on Manam (Papua New Guinea) — July 1988
Scientific Event Alert Network Bulletin, vol. 13, no. 7 (July 1988)
Managing Editor: Lindsay McClelland.
Manam (Papua New Guinea) Ash and incandescent tephra
Please cite this report as:
Global Volcanism Program, 1988. Report on Manam (Papua New Guinea). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 13:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198807-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
"Mild activity continued during July. Southern Crater emitted weak to moderate pale-grey ash and vapour clouds. Weak roaring and rumbling sounds were often heard, and incandescent lava fragments were ejected on 14 and 28 July. Main Crater commonly emitted weak-moderate white vapour that possibly contained ash during a period from 27 to 29 July when both craters released blue vapours. Tilt measurements indicated a slight radial deflation of ~0.5 µrad in July, continuing a weak deflationary trend that began in mid-October 1987. Total deflation measured at Tabele Observatory since that time is ~6 µrad."
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 and P. Lowenstein, RVO.