Report on Rabaul (Papua New Guinea) — 5 September-11 September 2007
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 5 September-11 September 2007
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2007. Report on Rabaul (Papua New Guinea) (Sennert, S, ed.). Weekly Volcanic Activity Report, 5 September-11 September 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 ash plumes from Rabaul caldera's Tavurvur cone rose to an altitude less than 1 km (3,300 ft) a.s.l. and drifted W on 3 September. Ashfall was reported from areas downwind. During 4-10 September, white vapor plumes rose to altitudes less than 2 km (6,600 ft) a.s.l. and drifted WNW. On 8 and 9 September, the smell of hydrogen-sulfide gas coincided with a blue tinge in the vapor plumes. During the reporting period, emissions were accompanied by roaring noises and observers saw incandescence at the summit.
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 asymmetrical 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 1,400 years ago. An earlier caldera-forming eruption about 7,100 years ago is thought to have originated from Tavui caldera, offshore to the north. Three small stratovolcanoes lie outside the N and NE caldera rims. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and W 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)