Report on Ulawun (Papua New Guinea) — November 2003

Bulletin of the Global Volcanism Network, vol. 28, no. 11 (November 2003)
Managing Editor: Edward Venzke.

Ulawun (Papua New Guinea) Intermittent ash plumes during September-October

Please cite this report as:

Global Volcanism Program, 2003. Report on Ulawun (Papua New Guinea). In: Venzke, E (ed.), Bulletin of the Global Volcanism Network, 28:11. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN200311-252120.

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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)


The Darwin Volcanic Ash Advisory Centre reported that an ash plume from Ulawun was visible on satellite imagery on 22 September at an altitude of ~3.7 km extending NW. On 5 October a faint ash plume was identified on satellite imagery at ~4.3 km altitude, extending 55 km WSW of the summit. Another ash plume was seen reaching ~75 km WNW of the summit on satellite imagery on 10 October at an altitude around 3 km.

According to the Rabaul Volcano Observatory, the main summit crater at Ulawun released weak to moderate volumes of white-gray vapor emissions over the period 6 November-22 December 2003. The two north valley vents were quiet, with no emissions observed. The seismograph, restored on 31 October 2003; showed seismicity was low throughout this period, with small low frequency volcanic earthquakes and some high frequency volcano-tectonic events. The electronic tiltmeter, restored at the same time; recorded no significant changes.

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: Ima Itikarai, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea (Email: hguria@global.net.pg); Darwin Volcanic Ash Advisory Centre (VAAC), Commonwealth Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom. gov.au/info/vaac/, Email: darwin.vaac@bom.gov.au).