Report on Rabaul (Papua New Guinea) — 29 November-5 December 2006
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 29 November-5 December 2006
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2006. Report on Rabaul (Papua New Guinea) (Sennert, S, ed.). Weekly Volcanic Activity Report, 29 November-5 December 2006. Smithsonian Institution and US Geological Survey.
Papua New Guinea
4.2459°S, 152.1937°E; summit elev. 688 m
All times are local (unless otherwise noted)
RVO reported that during 26-27 November Rabaul emitted weak gray ash clouds that drifted NW to W. Ashfall was reported from areas downwind. During 28 November-1 December, the emissions were forceful and plumes rose to 900 m (3,000 ft) a.s.l. and drifted E. On 2 December, emissions of white vapor and gray ash clouds produced plumes to 2.7 km (8,900 ft) a.s.l. that drifted ENE. During 3-6 December, ash plumes rose to altitudes of 1.2-2.7 km (3,900-8,900 ft) a.s.l. and drifted in multiple directions. Ashfall was again reported from areas downwind. Seismicity continued at low levels and deformation rates were low.
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)