Based on information from the Vanuatu Geohazards Observatory, the Wellington VAAC reported that on 26 May an ash plume from Gaua rose to an altitude of 3 km (10,000 ft) a.s.l.

Source: Wellington Volcanic Ash Advisory Center (VAAC)

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. Eruptions have been frequent since the onset of activity from a vent high on the SE flank in 1962.