Report on Rabaul (Papua New Guinea) — 23 October-29 October 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 October-29 October 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Rabaul (Papua New Guinea). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 23 October-29 October 2002. 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)
An eruption on 20 October from Tavurvur volcano took place at Rabaul caldera. The head of RVO stated that rocks were thrown 700 m from the summit and no lava was erupted. Ash from the eruption caused Tokua airport flights to be suspended on 22 October. It reopened on the 27th, with two flights permitted during the day. Reopening the airport was possible because ash from the eruption shifted away from it. Several small explosions occurred after the 20 October eruption and sent ash clouds to 4 km a.s.l. On the 28th RVO stated that a major increase in volcanic activity seemed unlikely.
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.