Report on Ambae (Vanuatu) — 27 September-3 October 2017
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 September-3 October 2017
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2017. Report on Ambae (Vanuatu). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 27 September-3 October 2017. Smithsonian Institution and US Geological Survey.
15.389°S, 167.835°E; summit elev. 1496 m
All times are local (unless otherwise noted)
On 28 September the Vanuatu Geohazards Observatory (VGO) stated that activity at Aoba remained at a moderate level. The Alert Level remained at (the second highest level on a scale of 0-5) and VGO reminded residents and tourists to stay outside of the Red Zone defined as a 6.5 km radius around Manaro Lakua cone (Manaro Voui). According to news sources, island officials ordered the evacuation of all of the island inhabitants, and by 4 October about 11,600 people had been evacuated. A 4 October news article noted that during the past week tephra had fallen on local villages.
Geologic Background. The island of Ambae, also known as Aoba, is a massive 2500 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.