Based on information from the Vanuatu Geohazards Observatory and analyses of satellite imagery, the Wellington VAAC reported that during 18-19 and 21-22 May ash plumes from Gaua rose to an altitude of 3 km (10,000 ft) a.s.l. and occasionally drifted W.

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 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.

Source: Wellington Volcanic Ash Advisory Center (VAAC)