Report on Gaua (Vanuatu) — 5 May-11 May 2010
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 5 May-11 May 2010
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2010. Report on Gaua (Vanuatu) (Sennert, S, ed.). Weekly Volcanic Activity Report, 5 May-11 May 2010. Smithsonian Institution and US Geological Survey.
14.281°S, 167.514°E; summit elev. 729 m
All times are local (unless otherwise noted)
On 11 May the Vanuatu Geohazards Observatory reported that field observations of Gaua revealed continued activity during April through the beginning of May. Significant emissions of gas and ash caused damage to vegetation around the crater and in areas on the NW, W, and SW parts of the island, the dominant wind directions. Lahars on the W part of the island were seen in April. Seismic data revealed that tremors had become more frequent since the beginning of the year. The Vanuatu Volcano Alert Level (VVAL) remained at 2 (on a scale of 0-4).
Geological Summary. The roughly 20-km-diameter Gaua Island, also known as Santa Maria, consists of a basaltic-to-andesitic stratovolcano with an 6 x 9 km summit caldera. Small parasitic vents near the caldera rim fed Pleistocene lava flows that reached the coast on several sides of the island; littoral cones were formed where these lava flows reached the ocean. Quiet collapse that formed the roughly 700-m-deep caldera was followed by extensive ash eruptions. The active Mount Garet (or Garat) cone in the SW part of the caldera has three pit craters across the summit area. Construction of Garet and other small cinder cones has left a crescent-shaped lake. The onset of eruptive activity from a vent high on the SE flank in 1962 ended a long period of dormancy.