Report on Rabaul (Papua New Guinea) — October 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 10 (October 1990)
Managing Editor: Lindsay McClelland.
Rabaul (Papua New Guinea) Seismicity remains low; no significant deformation
Please cite this report as:
Global Volcanism Program, 1990. Report on Rabaul (Papua New Guinea) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 15:10. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199010-252140
Papua New Guinea
4.2459°S, 152.1937°E; summit elev. 688 m
All times are local (unless otherwise noted)
"Seismicity remained at a low level in October. The total number of events recorded was 101 . . . . All events were of ML <=1. Only two were locatable, on the N and W sides of the caldera seismic zone. No significant changes were observed from levelling, EDM, tilt, tide gauge, and gravity measurements."
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: C. McKee and I. Itikarai, RVO.