Report on Rabaul (Papua New Guinea) — 3 September-9 September 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
3 September-9 September 2014
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2014. Report on Rabaul (Papua New Guinea). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 3 September-9 September 2014. 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)
During 31 August-5 September, Rabaul caldera’s Tavurvur cone remained quiet and no nighttime incandescence was observed. Variable amounts of white vapor were visible rising from the summit as well as traces of blue vapor. A few short-duration rumbling noises were heard during 30-31 August, and seismicity remained very high and dominated by small, low-frequency earthquakes. However, earthquakes decreased from 80 events per hour to 15 events per hour at 0300 on 31 August. Less than 10 earthquakes were detected during 1-2 September; a slight increase in low-frequency earthquakes was detected during 4-5 September.
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)