Garbuna remained relatively quiet between mid-February and mid-April 2006. The two vents at the summit released weak to moderate volumes of white vapor during this time, but no glow was observed. There was a weak rumbling noise on 14 April. Seismic activity remained at a low level. Few earthquakes were recorded during February and March; the daily average number of high-frequency events was 3 and of low-frequency events between 0 and 5. In April, a few earthquake swarms were recorded with individual events every 1-2 minutes. These episodes lasted less than 20 minutes. Low-frequency earthquakes occurred at the rate of 3-5 times per day and the Real-time Seismic Amplitude Measurement (RSAM) data was at background level fluctuating between 8 and 51 units.

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.

Information Contacts: Ima Itikarai and Herman Patia, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.