Report on Manam (Papua New Guinea) — February 1989
Scientific Event Alert Network Bulletin, vol. 14, no. 2 (February 1989)
Managing Editor: Lindsay McClelland.
Manam (Papua New Guinea) Tephra ejection; B-type seismicity
Please cite this report as:
Global Volcanism Program, 1989. Report on Manam (Papua New Guinea) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 14:2. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198902-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
"Manam showed a slight increase in activity during February. Fluctuating night glows and weak ejections of pyroclasts to 40-80 m above the rim of Southern Crater were observed on the 1st-4th and 21st. Emissions from Southern Crater consisted of pale-grey ash/vapour clouds and blue vapour. Deep rumbling noises from this crater were heard during the first few days of the month and for most of its second half. Main Crater's activity was very weak, consisting of white vapour emissions. Seismicity remained at a low-moderate level with daily totals of 900-1,200 small B-type events. There were no significant tilt changes."
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: D. Lolok and C. McKee, RVO.