Report on Manam (Papua New Guinea) — January 1999
Bulletin of the Global Volcanism Network, vol. 24, no. 1 (January 1999)
Managing Editor: Richard Wunderman.
Manam (Papua New Guinea) Continuing Vulcanian activity at Main Crater
Please cite this report as:
Global Volcanism Program, 1999. Report on Manam (Papua New Guinea) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 24:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199901-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
Emissions through January at Main Crater were generally pale brown, low in ash content, and were accompanied by roaring and rumbling sounds. There was no night glow. Ash clouds rose ~500 m above the summit and resulted in occasional ashfalls on the NW side of the island.
Southern Crater continuously released a small volume of white vapors. Only once, on 1 January, a small emission of pale gray ash was seen. Faint, fluctuating glow was observed around the center on most nights.
Seismicity remained at a low level with about 1,200-1,420 low-frequency B-type events of very low amplitude recorded daily. The water-tube tiltmeter at Tabele Observatory (4 km from the summit) showed no significant change. Since the Strombolian eruption on 21 December, the tilt trend was generally flat.
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: Herman Patia, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.