Report on Ulawun (Papua New Guinea) — December 1991
Bulletin of the Global Volcanism Network, vol. 16, no. 12 (December 1991)
Managing Editor: Lindsay McClelland.
Ulawun (Papua New Guinea) Vapor emission and seismicity
Please cite this report as:
Global Volcanism Program, 1991. Report on Ulawun (Papua New Guinea) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 16:12. Smithsonian Institution.
Papua New Guinea
5.05°S, 151.33°E; summit elev. 2334 m
All times are local (unless otherwise noted)
"Ulawun remained in a non-erupting state, releasing only weak to moderate white vapour. A slight increase in seismicity occurred in December after waning temporarily at the beginning of October (BGVN 16:10). Seismic activity consisted of low-frequency earthquakes, with daily counts fluctuating between 10 and 182. High-frequency volcanic earthquakes were also recorded occasionally through the month. Ground deformation continued to show no significant change."
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 N coast of the island of New Britain across a low saddle NE of Bamus volcano, the South Son. The upper 1,000 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: D. Lolok and B. Talai, RVO.