Report on Rabaul (Papua New Guinea) — June 1991
Bulletin of the Global Volcanism Network, vol. 16, no. 6 (June 1991)
Managing Editor: Lindsay McClelland.
Rabaul (Papua New Guinea) Seismicity remains low; no significant deformation
Please cite this report as:
Global Volcanism Program, 1991. Report on Rabaul (Papua New Guinea) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 16:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199106-252140
Papua New Guinea
4.2459°S, 152.1937°E; summit elev. 688 m
All times are local (unless otherwise noted)
". . . In June . . . the seismicity remained at a very low level with only 99 events recorded, all ML <1. Only four events could be plotted and were distributed on the N and W sides of the caldera seismic zone. Levelling, tilt, and EDM measurements showed no significant change."
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.
Information Contacts: P. de Saint-Ours, RVO.