Report on Manam (Papua New Guinea) — September 1986
Scientific Event Alert Network Bulletin, vol. 11, no. 9 (September 1986)
Managing Editor: Lindsay McClelland..
Manam (Papua New Guinea) Dense ash clouds; light ashfall; roaring
Please cite this report as:
Global Volcanism Program, 1986. Report on Manam (Papua New Guinea). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 11:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198609-251020.
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 September with a slight decline from the 17th from Southern Crater. Emissions from Southern Crater from the 1st to the 11th consisted of dense grey-brown ash clouds. Light ashfalls were reported on the downwind side of the island on most days. A slight decline in the emission rate was noticed from 12 September. Sub-continuous deep roaring noises from Southern Crater were reported from the 1st to the 16th and on the 20th. Activity from Main Crater remained constant throughout with the emission of weak grey-brown ash clouds. Seismicity remained at inter-eruptive levels with daily totals of ~1,300 events between the 1st and 16th, and ~1,100 from the 17th. No significant tilt changes 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: C. McKee, RVO.