Report on Rabaul (Papua New Guinea) — April 1992
Bulletin of the Global Volcanism Network, vol. 17, no. 4 (April 1992)
Managing Editor: Lindsay McClelland.
Rabaul (Papua New Guinea) Low-level seismicity
Please cite this report as:
Global Volcanism Program, 1992. Report on Rabaul (Papua New Guinea) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 17:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199204-252140
Papua New Guinea
4.271°S, 152.203°E; summit elev. 688 m
All times are local (unless otherwise noted)
"Seismic activity was at a low level in April. The month's total number of caldera earthquakes was 166 . . .. The highest daily totals were 43 and 32, recorded on 28 and 29 April, and consisted mostly of events in the W part of the caldera seismic zone, near Vulcan cone. Three of these events were felt, all registering at ML 2.8. Other earthquakes were located in the S and E parts of the caldera seismic zone."
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, RVO.