Report on Manam (Papua New Guinea) — October 1995
Bulletin of the Global Volcanism Network, vol. 20, no. 10 (October 1995)
Managing Editor: Richard Wunderman.
Manam (Papua New Guinea) Passive degassing
Please cite this report as:
Global Volcanism Program, 1995. Report on Manam (Papua New Guinea). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 20:10. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199510-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
Activity was low during October. During the month, both summit craters released only white vapors at low to moderate rates and both audible sounds and summit-crater night glow were absent. During the first three weeks of October, the daily totals of low-frequency earthquakes were at 200-500, but by month's end they increased to 800-1,300. Coincident with the increase, earthquake amplitudes also rose by ~50%. No visual changes accompanied the increase in seismicity. However, data from tiltmeters (4 km SW of the summit) showed a deflation of approximately 1.5 m µrad beginning around the second half 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: Ben Talai, RVO.