Report on Rabaul (Papua New Guinea) — April 2004
Bulletin of the Global Volcanism Network, vol. 29, no. 4 (April 2004)
Managing Editor: Edward Venzke.
Rabaul (Papua New Guinea) Tavurvur cone's eruptions pause or cease, starting 17 February; MODIS data
Please cite this report as:
Global Volcanism Program, 2004. Report on Rabaul (Papua New Guinea). In: Venzke, E. (ed.), Bulletin of the Global Volcanism Network, 29:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200404-252140.
Papua New Guinea
4.271°S, 152.203°E; summit elev. 688 m
All times are local (unless otherwise noted)
The Rabaul Volcano Observatory has reported that eruptive activity from the Tavurvur crater at Rabaul, which began in early October 2002, ceased on 17 February 2004. Activity during 1-17 February was characterized by emissions of light pale ash clouds with occasional moderate explosions producing thick ash plumes. The plumes rose 1-2 above the summit, resulting in ashfall to the E and NE, including in Duke of York. A slight change in wind direction on 6 and 13-15 February resulted in fine ashfall to the NW over Rabaul city and villages downwind. Occasional weak roaring noises were heard with some of the explosions on 5 and 11 February.
Seismic activity was consistent with the ash emissions, with one high frequency event NE of the caldera on 5 February. The real-time GPS and electronic tilt site on Matupit Island, in the center of the caldera, showed a deflationary trend since the middle of the month, a reversal of the long-term trend of slow gradual uplift reported earlier (BGVN 28:03, 28:09, and 28:11). During 18-29 February Tavurvur released weak white, and occasional blue, vapor.
A review of MODIS data for the year to 11 May 2004 showed thermal alerts recorded at Tavurvur cone, Rabaul, on 12, 21, and 29 October; 1, 8, 15, and 24 November; 1 and 26 December 2003; and 9 and 25 January 2004.
Geologic Background. The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor utilized by what was the island's largest city prior to a major eruption in 1994. The outer flanks of the 688-m-high asymmetrical pyroclastic shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the east, where its floor is flooded by Blanche Bay and was formed about 1400 years ago. An earlier caldera-forming eruption about 7100 years ago is now considered to have originated from Tavui caldera, offshore to the north. Three small stratovolcanoes lie outside the northern and NE caldera rims. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and western caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city.
Information Contacts: Ima Itikarai and Herman Patia, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea; Rob Wright, Luke Flynn, and Eric Pilger; MODIS Thermal Alert System, Hawaii Institute of Geophysics and Planetology (HIGP), School of Ocean and Earth Science and Technology, University of Hawaii at Manoa (URL: http://modis.hgip.hawaii.edu/).