Report on Bagana (Papua New Guinea) — May 1983
Scientific Event Alert Network Bulletin, vol. 8, no. 5 (May 1983)
Managing Editor: Lindsay McClelland.
Bagana (Papua New Guinea) Increased vapor emission; sluggish lava flow
Please cite this report as:
Global Volcanism Program, 1983. Report on Bagana (Papua New Guinea). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 8:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198305-255020.
Papua New Guinea
6.137°S, 155.196°E; summit elev. 1855 m
All times are local (unless otherwise noted)
From 5-7 March, the weak white vapor emissions from the summit increased to a thick high-pressure plume rising to 2,000 m above the summit. Vapor release remained high until 21 March, but no glow was reported. Vapor emission was again strong at the end of the month.
Aerial inspections on the mornings of 15, 16, and 17 March revealed a thick but apparently normal plume being released from the lava dome occupying the summit crater. The viscous blocky lava flow on the N flank appeared to be moving extremely slowly, perhaps a few meters per week. At the source of this flow, the maximum lava temperature (measured by a portable infrared optical pyrometer from a helicopter) was only 175°C on the slow-moving, blocky surface.
During 24 hours of seismic monitoring from the W flank at 1,100 m altitude, 540 B-type events and one or two sharp, impulsive, shallow events were recorded.
Geologic Background. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50 m thick with prominent levees that descend the flanks on all sides.
Information Contacts: P. de Saint-Ours, RVO.