Report on Ulawun (Papua New Guinea) — April 1993
Bulletin of the Global Volcanism Network, vol. 18, no. 4 (April 1993)
Managing Editor: Edward Venzke.
Ulawun (Papua New Guinea) Tremor level returns to background
Please cite this report as:
Global Volcanism Program, 1993. Report on Ulawun (Papua New Guinea). In: Venzke, E. (ed.), Bulletin of the Global Volcanism Network, 18:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199304-252120.
Papua New Guinea
5.05°S, 151.33°E; summit elev. 2334 m
All times are local (unless otherwise noted)
"Activity continued at the low levels reported in the previous two months. Emissions of weak-to-moderate white vapour occurred throughout April, with stronger emissions on 3 and 6 April. Seismic activity was low throughout the month. RSAM showed that the slow decline in tremor amplitude seen in March continued until 20 April. After 20 April, the tremor amplitude remained constant, indicating that tremor had effectively ceased and the natural background noise was being recorded."
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: N. LauerR. Stewart, and C. McKee, RVO.