Vanuatu Geohazards Observatory reported that the seismic network monitoring Gaua detected volcanic activity in August. Gas plumes were detected by the OMI satellite on 17, 27, and 28 September, and ashfall was reported in the N, E, and W parts of Gaua on 10 October by local authorities. The Alert Level remained at 1 (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 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: Vanuatu Meteorology and Geohazards Department (VMGD)