RVO reported that forceful emissions of dense white plumes from Garbuna were accompanied by intermittent ash emissions during 1-4 October to an altitude of 1.6 km (5,200 ft) a.s.l. Occasional weak roaring and rumbling noises were reported in Garu village, about 9 km NW. An overflight on 3 October revealed that existing vents at the summit had increased in size and new vents and fumaroles appeared in the E sector of the lava dome. The main vent that had been restricted to the outside flank of the cone had enlarged considerably (more than tripled in size) and merged with the November 2005 vent. The original vent that opened on 17 October 2005 was larger and vigorously fuming. Although there was little evidence of juvenile material having been ejected and there was surprisingly little eruptive material around the summit, it and areas more than 1 km away from the active vents were cratered, possibly from lithic bombs. Fumarolic activity in the summit region away from the currently active vents had ceased.

Geological Summary. The basaltic-to-dacitic Krummel-Garbuna-Welcker Volcanic Complex consists of three volcanic peaks located along a 7-km N-S line above a shield-like foundation at the southern end of the Willaumez Peninsula. The central and lower peaks of the centrally located Garbuna contain a large vegetation-free area that is probably the most extensive thermal field in Papua New Guinea. A prominent lava dome and blocky lava flow in the center of thermal area have resisted destruction by thermal activity, and may be of Holocene age. Krummel volcano at the south end of the group contains a summit crater, breached to the NW. The highest peak of the group is Welcker volcano, which has fed blocky lava flows that extend to the eastern coast of the peninsula. The last major eruption from both it and Garbuna volcanoes took place about 1800 years ago. The first historical eruption took place at Garbuna in October 2005.

Source: Rabaul Volcano Observatory (RVO)