Report on Ulawun (Papua New Guinea) — May 1994
Bulletin of the Global Volcanism Network, vol. 19, no. 5 (May 1994)
Managing Editor: Richard Wunderman
Ulawun (Papua New Guinea) Seismically active and continuing to emit dark vapor
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, 19:5. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN199405-252120.
Papua New Guinea
5.05°S, 151.33°E; summit elev. 2334 m
All times are local (unless otherwise noted)
The increase in the level of venting activity . . . continued into May. Throughout the month the summit crater emitted moderate to thick white vapor, although there were occasional reports of gray and blue emissions on 17 and 18 May, and towards the end of the month. On 23 May, because of the ash cloud, pilots in the region were notified to "exercise caution and to report any increase in activity including height and movement of the ash cloud." In addition, during most nights in the first three weeks of the month the crater emitted a red glow that remained weak but steady.
May seismic activity underwent a slight progressive decrease: Daily earthquake totals early in the month were in the range 400-600; by month's end they had dropped to 400. Since the end of April earthquake amplitudes also decreased.
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: I. Itikarai, and C. McKee, RVO; BOM, Darwin.