Report on Ulawun (Papua New Guinea) — July 1994
Bulletin of the Global Volcanism Network, vol. 19, no. 7 (July 1994)
Managing Editor: Richard Wunderman
Ulawun (Papua New Guinea) White vapor emissions and low-frequency tremor
Please cite this report as:
Global Volcanism Program, 1994. Report on Ulawun (Papua New Guinea). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 19:7. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN199407-252120.
Papua New Guinea
5.05°S, 151.33°E; summit elev. 2334 m
All times are local (unless otherwise noted)
"The level of activity . . . was slightly lower in July . . . . The summit crater continued to emit mainly white vapour, of variable volume. Faint blue vapour emissions were seen on 3, 5, 9, and 20 July. No sounds or night glow were reported.
"Seismic activity . . . continued the pattern of previous months, with mainly sub-continuous, low-level, low-frequency tremor, and the occasional larger low-frequency earthquake. Only two high-frequency earthquakes were recorded during the month. Amplitude measurements and RSAM monitoring were made difficult at the start of the month by storm-generated noise. However, both showed a gradual increase through the month until about 23 July when there were sharp drops; gradual increases were again seen through the end of the month."
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: B. Talai, R. Stewart, and C. McKee, RVO.