Report on Manam (Papua New Guinea) — August 1994
Bulletin of the Global Volcanism Network, vol. 19, no. 8 (August 1994)
Managing Editor: Richard Wunderman..
Manam (Papua New Guinea) Ash ejections from Southern Crater up to 1,000 m above the summit
Please cite this report as:
Global Volcanism Program, 1994. Report on Manam (Papua New Guinea). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 19:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199408-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
"Increased activity at Southern Crater began on 8 August following a week of low-level activity. This change initiated with weak emissions of thick grey ash clouds. On the 9th, the emissions changed to forceful ejections of thick grey-brown ash clouds that caused light ashfall on the NW side of the volcano. Activity subsided after the 11th, but started again on the 18th and continued until 30 August. The thick grey-brown ash columns rose ~400-1,000 m above the summit. Most of the ash ejections were associated with explosion and low roaring and/or rumbling noises. Incandescent lava fragment projections were seen on 23 and 26-30 August.
"Activity from Main Crater consisted of emissions of weak-to-moderate white vapour through August. No noises or night glows were observed. Seismicity remained at low levels throughout the month except for a brief period during 21-29 August when it was moderate. This coincided with the period of thick brown ash cloud emissions and incandescent lava fragment projections. On average, ~1,200 volcanic earthquakes were recorded each day."
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: I. Itikarai, R. Stewart, and C. McKee, RVO.