Report on Manam (Papua New Guinea) — October 1998
Bulletin of the Global Volcanism Network, vol. 23, no. 10 (October 1998)
Managing Editor: Richard Wunderman.
Manam (Papua New Guinea) Intense eruptive activity resumes in late September
Please cite this report as:
Global Volcanism Program, 1998. Report on Manam (Papua New Guinea) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 23:10. Smithsonian Institution.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
An inflation of ~10 µrad for September was recorded at Tabele Observatory, ~3 km SW of the summit. This deformation, together with increased seismicity, audible rumblings, and night glow evident in the middle of the month, was thought to indicate the onset of renewed activity.
Intense eruptive activity resumed at Manam in late September for the first time since its fatal eruption of November-December 1996. A visible increase in activity started during 23-26 September, with intermittent dark ash emissions and incandescent projections at night to ~200 m above South Crater. On subsequent days activity decreased to continuous white vapor emissions, first profuse then very weak, and occasional roaring sounds and fluctuating red glow. This corresponded to a slight decrease in seismic amplitude levels, but the radial tilt kept showing inflation.
Significant eruptive activity throughout October, including ash emissions, pyroclastic flows, and lava flows, will be described in the next issue.
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: Patrice de Saint-Ours, Steve Saunders, and Ben Talai, RVO.