Report on Bagana (Papua New Guinea) — March 1987
Scientific Event Alert Network Bulletin, vol. 12, no. 3 (March 1987)
Managing Editor: Lindsay McClelland..
Bagana (Papua New Guinea) Lava flow active; stronger seismicity
Please cite this report as:
Global Volcanism Program, 1987. Report on Bagana (Papua New Guinea). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 12:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198703-255020.
Papua New Guinea
6.137°S, 155.196°E; summit elev. 1855 m
All times are local (unless otherwise noted)
Eruptive activity continued through March, apparently accompanied by increased seismicity. The summit vent emitted mostly moderate to strong white to brown-gray vapor and ash clouds. Blue vapour emissions were observed 17-19 March. Weak summit glows were reported on most nights and incandescent lava fragments were ejected to ~50 m above the summit on 31 March. Rumbling sounds accompanied the eruption. Rockslides from the edges of the lava flow on the N and NW flanks indicated that effusion was continuing.
Although seismic recordings were intermittent, seismicity appeared to have begun increasing on 11 March [see also 12:4]. The highest daily total of volcanic earthquakes was 110. A total of 333 earthquakes were recorded for the month (the highest total since September 1986) but the actual number of earthquakes could have been significantly higher.
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: B. Talai and P. Lowenstein, RVO.