Report on Rabaul (Papua New Guinea) — 11 July-17 July 2007
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
11 July-17 July 2007
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2007. Report on Rabaul (Papua New Guinea). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 11 July-17 July 2007. Smithsonian Institution and US Geological Survey.
Papua New Guinea
4.271°S, 152.203°E; summit elev. 688 m
All times are local (unless otherwise noted)
RVO reported that during 10-11 July, ash plumes from Rabaul caldera's Tavurvur cone rose to an altitude less than 1.2 km (3,900 ft) a.s.l. and drifted N and NW. Fine ash fell in areas downwind, including Rabaul Town. During 12-14 July, white and blue vapor plumes drifted N and NW. A mild smell of sulfur gas was reported from areas downwind. On 17 July, an explosion was accompanied by a loud booming noise and an ash plume. The flanks were showered with lava fragments. The ash plume rose to an altitude less than 1.2 km (3,900 ft) a.s.l. and drifted NW. Ashfall was reported from Rabaul Town, Malaguna, and surrounding areas. White and blue vapor plumes were observed during 14-16 July. Roaring noises were heard and incandescence was visible at night.
Geological Summary. 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.
Source: Rabaul Volcano Observatory (RVO)