Report on Ambae (Vanuatu) — 30 November-6 December 2005
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 November-6 December 2005
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2005. Report on Ambae (Vanuatu). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 30 November-6 December 2005. Smithsonian Institution and US Geological Survey.
15.389°S, 167.835°E; summit elev. 1496 m
All times are local (unless otherwise noted)
On 27 November the Aoba volcano (also locally called Mt. Manaro) erupted on Ambae Island in Vanuatu. There have been no casualties reported, but volcanic ash has blanketed houses and food crops. There are concerns that the ash may affect the respiratory systems of local residents and contaminate water sources. The government of Vanuatu has declared the island a disaster zone, and by 6 December 5,000 residents in at least 15 communities in high-risk areas had relocated to safe areas. White steam billowing to 1,500 m above the summit and 2,000 tons of ash per day falling on the island have been reported. The level of Lake Voui, one of the lakes in the summit crater, is now only 150 m below the rim, raising the possibility of floods or lahars if large volumes of lake water are ejected. A small cone is also growing within the crater lake.
Geologic Background. The island of Ambae, also known as Aoba, is a massive 2,500 km3 basaltic shield that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes (Manaro Ngoru, Voui, and Manaro Lakua) is located at the summit within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. That large central edifice is also called Manaro Voui or Lombenben volcano. Post-caldera explosive eruptions formed the summit craters about 360 years ago. A tuff cone was constructed within Lake Voui (or Vui) about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.