Report on Gaua (Vanuatu) — May 2013
Bulletin of the Global Volcanism Network, vol. 38, no. 5 (May 2013)
Managing Editor: Richard Wunderman.
Gaua (Vanuatu) Hazard status raised; emissions continue into 2013; plume observed from above
Please cite this report as:
Global Volcanism Program, 2013. Report on Gaua (Vanuatu) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 38:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN201305-257020.
14.27°S, 167.5°E; summit elev. 797 m
All times are local (unless otherwise noted)
In our June 2012 Bulletin report (BGVN 37:06), we noted ongoing eruptions from Gaua during much of 2011.
On 5 December 2011, the Vanuatu Meteorology and Geohazards Department (VMGD) changed the status of Gaua volcano from a dormant to an active volcano. An index map showing Vanautu appears in the Ambrym report in this issue.
The Wellington Volcanic Ash Advisory Center (VAAC) reported that on 29 April 2013 a plume from Gaua was observed from an aircraft. Absent were further comments. Satellite imagery did not indicate ash. Astronauts on the International Space Station saw and photographed Gaua's E-blowing plume on 31 May 2013 (figure 24).
The Alert Level of Gaua remained at level 1 (out of 4) signifying that changes in Gaua's activity could occur without, or with little, warning. VMGD continued this status through at least mid-August 2013, although they noted as slight increase in tremor since their June report.
This status indicates that ash falls will continue to be expected in areas exposed to trade winds. Strong degassing of the volcano could be accompanied with acid rainfall.
During the year ending in mid-July 2013, there were no MODVOLC thermal alerts.
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.
Information Contacts: Vanuatu Geohazards Observatory (URL: http://www.vmgd.gov.vu/vmgd/); Vanuatu Meteorology and Geohazards Department (URL: http:// http://www.meteo.gov.vu/); Wellington Volcanic Ash Advisory Center (VAAC) (URL: vaac.metservice.com); and Hawai'i Institute of Geophysics and Planetology, MODVOLC Thermal Alert System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i , 2525 Correa Road, Honolulu, HI 96822 USA (URL: http://modis.higp.hawaii.edu/).