Report on Ulawun (Papua New Guinea) — December 1987

Scientific Event Alert Network Bulletin, vol. 12, no. 12 (December 1987)
Managing Editor: Lindsay McClelland.

Ulawun (Papua New Guinea) Volcanic earthquakes increase; vapor emission

Please cite this report as:

Global Volcanism Program, 1987. Report on Ulawun (Papua New Guinea). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 12:12. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.SEAN198712-252120.

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Ulawun

Papua New Guinea

5.05°S, 151.33°E; summit elev. 2334 m

All times are local (unless otherwise noted)


When visible, the summit crater was releasing moderate amounts of white vapour during December. The daily totals of volcanic earthquakes increased on 2 December and averaged ~150 until the 17th. A further, but somewhat irregular, increase began on the 18th and reached a peak of ~800 events/day on 23 and 24 December. Earthquakes then decreased steadily, stabilizing at ~350 events/day after 26 December. The summit was obscured throughout most of the period of increased seismicity.

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. Ulawun 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 of the 2334-m-high Ulawun volcano is unvegetated. A prominent E-W-trending escarpment on the south may be the result of large-scale slumping. Satellitic cones occupy the NW and eastern flanks. A steep-walled valley cuts the NW side of Ulawun volcano, 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: C. McKee and P. Lowenstein, RVO.