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Report on Bagana (Papua New Guinea) — November 1989


Scientific Event Alert Network Bulletin, vol. 14, no. 11 (November 1989)
Managing Editor: Lindsay McClelland.

Bagana (Papua New Guinea) Lava overflows summit crater; explosions

Please cite this report as:

Global Volcanism Program, 1989. Report on Bagana (Papua New Guinea) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 14:11. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198911-255020


Papua New Guinea

6.137°S, 155.196°E; summit elev. 1855 m

All times are local (unless otherwise noted)

"Mild sustained eruptive activity continued throughout November. Aerial reconnaissance on the 10th and 11th revealed that the summit, fully occupied by blocky lava, was overflowing on several sides. A main lava flow, active since 1987, extended to the foot of the volcano on the E flank (13:02). Lava also progressed slowly into the channel of the N lava flow (inactive since 1987), into the upper part of the prominent [1966-75] lava channel on the S flank, and spread over the upper NW flank. Very frequent rockfalls or avalanches occurred on all sides below the summit, producing short-lived red glow at night.

"An SO2-laden vapour plume, formed by numerous fumaroles in cracks in the lava-filled crater and the weathered upper flanks, quietly drifted as much as 20 km downwind. Slow and quiet lava effusion was only disturbed by occasional explosions (3, 16, and 25 November) which generated a black cloud above the summit. The seismicity continued to be dominated by rockfall events (2-94/day) and a few B-type events (0-4/day)."

Geological Summary. 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: D. Lolok and P. de Saint-Ours, RVO.