Report on Manam (Papua New Guinea) — September 1996
Bulletin of the Global Volcanism Network, vol. 21, no. 9 (September 1996)
Managing Editor: Richard Wunderman.
Manam (Papua New Guinea) Increased eruptive activity at both Main and South Craters
Please cite this report as:
Global Volcanism Program, 1996. Report on Manam (Papua New Guinea). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 21:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199609-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
During early September, both Main and South Craters emitted weak to moderate white vapor. Main Crater started to produce occasional puffs of gray vapor and ash on 13 September, and became more forceful and frequent (at a-few-minute intervals) the next day. This increased eruptive activity during mid-September resulted in very light ashfall over villages and garden areas on the NW side of the island. This is the first time that Main Crater has been active since mid-December 1992. The activity began to decline on 20 September. Occasional roaring or rumbling sounds were heard, but neither glow nor incandescent projection was seen at night. By 26 September emissions were weak and took place every 30 minutes.
During 16-29 September, activity at South Crater also slightly increased with occasional blue and gray emissions. Mild Vulcanian explosions took place every 5-10 minutes on 22-27 September. However, neither night glow nor incandescent projection was observed over the crater.
There was no seismic monitoring at Manam during September. Measurements from the water-tube tiltmeters at Tabele Observatory (4 km SW of the summit) have shown no tilt change since April 1996.
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: Chris McKee and Ben Talai, RVO.