Report on Rabaul (Papua New Guinea) — 6 February-12 February 2013
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 6 February-12 February 2013
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2013. Report on Rabaul (Papua New Guinea) (Sennert, S, ed.). Weekly Volcanic Activity Report, 6 February-12 February 2013. Smithsonian Institution and US Geological Survey.
Papua New Guinea
4.2459°S, 152.1937°E; summit elev. 688 m
All times are local (unless otherwise noted)
RVO reported that during 4-5 February pale gray ash plumes rose from Rabaul caldera's Tavurvur cone. On 5 February the ash plumes slowly rose 2 km a.s.l. and drifted E and ENE. On 6 February only white plumes rose from the crater during most of the day. In the evening a gray billowing ash cloud was followed by a sequence of "gentle puffs" of white to light gray ash emissions at irregular intervals into the night and through the morning of 7 February. Fine ashfall was reported in Rabaul town (3-5 km NW) in the late evening of 6 February.
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)