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Report on Gaua (Vanuatu) — 27 January-2 February 2010

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 January-2 February 2010
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2010. Report on Gaua (Vanuatu). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 27 January-2 February 2010. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (27 January-2 February 2010)


Gaua

Vanuatu

14.27°S, 167.5°E; summit elev. 797 m

All times are local (unless otherwise noted)


On 29 January, the Vanuatu Geohazards Observatory reported significant changes in Gaua's activity over the previous two weeks. They noted that since 16 January more gas was emitted and multiple explosions produced denser and darker ash plumes. During 22-29 January, the water level in the river to the E that Lake Letas feeds rose 10 cm. Gas-and-ash plumes rose 3 km and drifted S and W. On 24 January nearby villagers reported seeing ejected material from Strombolian activity. The Wellington VAAC reported that on 27 January an ash cloud was seen on satellite imagery. Strong explosions were seen and heard from East Gaua on 29 January. According to the VAAC, the Vanuatu Geohazards Observatory reported that gas-and-ash plumes rose to altitudes of 3 km (10,000 ft) a.s.l. and drifted S and W that same day.

Geologic Background. 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 wide summit caldera. Small parasitic vents near the caldera rim fed Pleistocene lava flows that reached the coast on several sides of the island; several littoral cones were formed where these lava flows reached the sea. Quiet collapse that formed the roughly 700-m-deep caldera was followed by extensive ash eruptions. Construction of the historically active cone of Mount Garat (Gharat) and other small cinder cones in the SW part of the caldera has left a crescent-shaped caldera lake. The symmetrical, flat-topped Mount Garat cone is topped by three pit craters. The onset of eruptive activity from a vent high on the SE flank in 1962 ended a long period of dormancy.

Sources: Vanuatu Meteorology and Geo-Hazards Department (VMGD), Wellington Volcanic Ash Advisory Center (VAAC)