Report on Manam (Papua New Guinea) — December 1997
Bulletin of the Global Volcanism Network, vol. 22, no. 12 (December 1997)
Managing Editor: Richard Wunderman.
Manam (Papua New Guinea) Moderate explosive activity during December
Please cite this report as:
Global Volcanism Program, 1997. Report on Manam (Papua New Guinea). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 22:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199712-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
Except for a few Vulcanian explosions at both craters during the first half of the month, moderate activity continued through December.
At Main Crater, mild Vulcanian explosions started at the end of November and prevailed until mid- December. The explosions' plumes rose more than 500 m above the crater resulting in ashfall on the island. A gray vapor of varying density was seen throughout the month.
Southern Crater activity increased following 29 November. Ash-producing explosions rising more than 600 m above the crater continued until 5 December. A weak but steady glow was visible nightly until 6 December. The usual emission was thin (sometimes thick) white vapor. Wisps of blue vapor were seen only on 2, 3, and 31 December.
Seismicity was moderate throughout the month with ~700-1,500 low-frequency, small-amplitude daily events. The water-tube tiltmeter at Tabele (4 km SW of the summit) showed a steady radial inflation of 1 µrad.
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.