Report on Manam (Papua New Guinea) — November 1986
Scientific Event Alert Network Bulletin, vol. 11, no. 11 (November 1986)
Managing Editor: Lindsay McClelland.
Manam (Papua New Guinea) Both summit craters emit ash
Please cite this report as:
Global Volcanism Program, 1986. Report on Manam (Papua New Guinea) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 11:11. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198611-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
"Both summit craters were at low eruptive levels throughout November. Southern Crater emitted [white vapour] until 11 November, and grey-brown, low-density ash clouds from 12 November to the end of the month. Main Crater emitted mostly grey-brown, low-density ash clouds with some periods of steaming. Weak sounds from Southern Crater were heard on 19 and 20 November and fine ash fell on the SE side of the island. No incandescence was seen.
"Seismicity did not change significantly during the month, with 1,200-1,300 B-type small-magnitude events recorded/day. About 1.5 µrad of inflationary tilt were recorded."
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: B. Talai and P. Lowenstein, RVO.