Report on Manam (Papua New Guinea) — July 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 7 (July 1990)
Managing Editor: Lindsay McClelland.
Manam (Papua New Guinea) Inflation resumes; seismicity fluctuates
Please cite this report as:
Global Volcanism Program, 1990. Report on Manam (Papua New Guinea). In: McClelland, L. (ed.), Bulletin of the Global Volcanism Network, 15:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199007-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
"Activity remained at a very low level. Emissions from both summit craters were characterized by weak white vapour. After 2 months of deflation, summit inflation resumed, as indicated by ~3 µrad of radial tilting recorded by the water tube tiltmeter at Tabele Observatory during July. The daily frequency of volcanic earthquakes decreased from 1,200 to 200 during the first three weeks then increased to 1,100 at the end of the month. Seismic amplitudes showed a decrease by half between the beginning and the end of the month."
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: H. Patia and C. McKee, RVO.