Report on Manam (Papua New Guinea) — 27 October-2 November 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 October-2 November 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Manam (Papua New Guinea). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 27 October-2 November 2004. Smithsonian Institution and US Geological Survey.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
The eruption that began at Manam on 24 October continued through at least 31 October. According to RVO, during 27-28 October there were occasional emissions of ash-laden brown clouds and projections of incandescent lava from Manam's Southern Crater. Fine ash from the eruptions traveled NW, and was deposited between the villages of Jogari and Baliau. Main Crater released occasional weak-to-moderate emissions of white vapor, and sometimes brown ash. Weak, fluctuating incandescence was visible from the crater at night. During 28-29 October, at Southern Crater there were occasional emissions of moderate, thick, dark ash-laden clouds that rose above normal atmospheric clouds. The ash clouds drifted NW, depositing ash between the villages of Yassa and Baliau. The Alert Level at Manam was at Stage 1. By 31 October, the eruption at Main Crater consisted of Strombolian activity, with ash and scoria emissions. Scoria of ~1 cm diameter and ash was deposited in Warisi village on the SE side of the island. Small pyroclastic flows were generated and fresh lava flowed into the NE valley. The lava flow followed the Boakure side of the valley, covering older flows from the 1992-1994 eruption. Beginning on the morning of the 31st, the amount of continuous volcanic tremor increased to moderate-to-high levels, so the Alert Level was increased to Stage 2. Villagers near the four main valleys near Manam were advised to remain away from the volcano.
The Darwin VAAC reported that a SE-drifting plume from Manam was visible on satellite imagery on 31 October during 0813-1449 at a height of ~13.7 km a.s.l. The Aviation Color Code was at Red, the highest level. According to a news report, about 4,000 villagers living near the volcano were moved to safer areas. Reportedly, "about 1 ft [0.3 m] of ash with hot pumice" landed on the roofs of houses, and ash drifted as far W as Wewak, ~100 km from Manam Island. On 2 November around 2325 a possible eruption may have produced a plume to a height of ~7.6 km a.s.l. that drifted SE.
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.