Volcanic Activity Report on Rabaul (Papua New Guinea) — 5 March-11 March 2003

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 5 March-11 March 2003
Managing Editor: Gari Mayberry

Please cite this report as:

Global Volcanism Program, 2003. Report on Rabaul (Papua New Guinea) (Mayberry, G, ed.). Weekly Volcanic Activity Report, 5 March-11 March 2003. Smithsonian Institution and US Geological Survey. https://volcano.si.edu/showreport.cfm?gvpvar=GVP.WVAR20030305-252140

Rabaul

Papua New Guinea

All times are local (unless otherwise noted)

The eruption at Rabaul caldera's Tavurvur cone continued during 26 February to 2 March. Activity was characterized by discrete, slow, convoluted ash plumes occurring at long, irregular intervals and rising slowly to several hundred to a thousand meters above the summit. Activity during the report period was slightly lower than activity during 17-26 February, with intervals between ash emissions becoming much longer. Ash emissions were blown to the E and SE. Seismicity remained at low levels and there were no significant changes in deformation. According to the Darwin VAAC, ash was not visible on satellite imagery.

Sources: Rabaul Volcano Observatory (RVO) via the Darwin Volcanic Ash Advisory Center, Darwin Volcanic Ash Advisory Centre (VAAC)

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.