Report on Ambae (Vanuatu) — 18 July-24 July 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
18 July-24 July 2018
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2018. Report on Ambae (Vanuatu). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 18 July-24 July 2018. Smithsonian Institution and US Geological Survey.
15.389°S, 167.835°E; summit elev. 1496 m
All times are local (unless otherwise noted)
Based on satellite data, webcam observations, and wind model data, the Wellington VAAC reported that during 17-24 July ash plumes from the vent at Ambae’s Lake Voui rose to altitudes of 2.1-5.5 km (7,000-18,000 ft) a.s.l. and drifted N, NE, E, and SE. According to news articles, activity intensified on 17 July with significant ashfall impacting the N and E parts of the island, causing dark conditions for residents. Rumbling noises were reported at Penama Provincial Headquarters at Saratamata, more than 30 km away. Volcanologists conducting field work in the areas noted widespread damage and disruption to the local population; roads going to the W part of the island had been washed away.
Geological Summary. 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.