Report on Ulawun (Papua New Guinea) — January 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 1 (January 1990)
Managing Editor: Lindsay McClelland.
Ulawun (Papua New Guinea) Weak vapor emission; 10-hour seismic swarm follows M 4.2 earthquake 25 km away
Please cite this report as:
Global Volcanism Program, 1990. Report on Ulawun (Papua New Guinea). In: McClelland, L (ed.), Bulletin of the Global Volcanism Network, 15:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199001-252120.
Papua New Guinea
5.05°S, 151.33°E; summit elev. 2334 m
All times are local (unless otherwise noted)
"Activity was at a low level throughout January, as it has been since July 1989. The summit crater emitted white vapour in weak to moderate amounts. The seismicity was also at a very low level, with only a few volcanic (B-type) events of very small amplitude/day. On the 4th, however, an earthquake (ML 4.2) originating 25 km away provoked the onset of a 10-hour swarm of small B-type events (~150) that ended abruptly after a string of a dozen larger events."
Geologic Background. The symmetrical basaltic-to-andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. The volcano, also known as the Father, rises above the north coast of the island of New Britain across a low saddle NE of Bamus volcano, the South Son. The upper 1000 m is unvegetated. A prominent E-W escarpment on the south may be the result of large-scale slumping. Satellitic cones occupy the NW and E flanks. A steep-walled valley cuts the NW side, and a flank lava-flow complex lies to the south of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater.
Information Contacts: I. Itikarai and P. de Saint-Ours, RVO.