Report on Bagana (Papua New Guinea) — January 1989
Scientific Event Alert Network Bulletin, vol. 14, no. 1 (January 1989)
Managing Editor: Lindsay McClelland.
Bagana (Papua New Guinea) Avalanche breaches summit; lava drains from crater
Please cite this report as:
Global Volcanism Program, 1989. Report on Bagana (Papua New Guinea). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 14:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198901-255020.
Papua New Guinea
6.137°S, 155.196°E; summit elev. 1855 m
All times are local (unless otherwise noted)
"A minor collapse took place near the summit early on 22 January. The summit was reported to be glowing bright red at about 0430, then changed from red to yellow as it became even brighter. This activity culminated in an avalanche of incandescent boulders down the SE flank . . . . Shortly afterward, a large plume of ash and vapour developed. Inspections . . . on 28 January and 3 February revealed that structural failure had occurred at the outflow point of the lava flow on the E edge of the summit. The breach that was formed allowed rapid drainage of lava, forming a crater at Bagana's summit. The lava in the crater has a flat surface and appears to be flowing freely through the breach.
"It is concluded that the bright glow from the summit seen on 22 January resulted from the emergence of a pulse of hotter, more fluid lava which destabilized the edge of the dome and initiated the breaching."
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: C. McKee, H. Patia, and P. de Saint-Ours, RVO.