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Report on Rabaul (Papua New Guinea) — 23 April-29 April 2008


Rabaul

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 23 April-29 April 2008
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2008. Report on Rabaul (Papua New Guinea) (Sennert, S, ed.). Weekly Volcanic Activity Report, 23 April-29 April 2008. Smithsonian Institution and US Geological Survey.

Weekly Report (23 April-29 April 2008)

Rabaul

Papua New Guinea

4.2459°S, 152.1937°E; summit elev. 688 m

All times are local (unless otherwise noted)


RVO reported that during 23-29 April ash and ash plumes from Rabaul caldera's Tavurvur cone rose to altitudes of 1.7-2.7 km (5,600-8,900 ft) a.s.l. and drifted N, NE, E, SE, and SW. Incandescence at night at the summit, intermittent roaring noises, and occasional explosions were reported. Ashfall measured over 1 cm thick nearby and E of Tavurvur during 23-24 April and was noted in other areas downwind during 25-29 April. Incandescent fragments were propelled from the summit at night during 27-28 April.

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.

Source: Rabaul Volcano Observatory (RVO)