Report on Yasur (Vanuatu) — September 2022
Bulletin of the Global Volcanism Network, vol. 47, no. 9 (September 2022)
Managing Editor: Edward Venzke. Research and preparation by Paul Berger.
Yasur (Vanuatu) Ongoing thermal anomalies, gas-and-ash explosions, and SO2 plumes through August 2022
Please cite this report as:
Global Volcanism Program, 2022. Report on Yasur (Vanuatu) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 47:9. Smithsonian Institution.
19.532°S, 169.447°E; summit elev. 361 m
All times are local (unless otherwise noted)
Recent activity at Yasur, which has been erupting since at least 1774 and possibly the past 750 years, includes frequent Strombolian explosions and ash and gas plumes from several vents in the 400 m-diameter summit crater (BGVN 44:02, 45:03). This report summarizes activity during September 2021-August 2022, using information from monthly bulletins of the Vanuatu Meteorology and Geo-Hazards Department (VMGD), the Wellington Volcanic Ash Advisory Center (VAAC), and various satellite data. According to VMGD, Yasur (also called Tanna, after the island on which it is located) has remained on Alert Level 2 (major unrest state, on a scale of 0-5), since 18 October 2016, and VMGD reminded the public not to enter the restricted area within a radius of 600 m around the cone (1 km radius 22 October-24 November 2021).
VMGD reported that seismic data and visual observations confirmed ongoing strong explosions with gas and/or ash plumes during the reporting period, with bombs falling in and around the crater, and infrequently on the flanks (figures 84-85). According to VMGD and the Wellington VAAC, emissions generally rose 1.2-1.8 km in altitude (0.8-1.4 km above the crater), sometimes depositing ash on nearby villages. The intensified activity caused VMGD to expand the restricted area to a 1-km radius around the cone. The heightened emissions had ceased by 1845 on 24 October.
|Figure 84. Webcam image of Yasur on 22 October 2021 showing an ash plume rising as high as 800 m above the summit. Courtesy of VMGD.|
|Figure 85. Webcam image of Yasur on 27 November 2021. According to VMGD and the Wellington VAAC, multiple gas-and-ash emissions that day rose to 1.5-1.8 km altitude and drifted W. Courtesy of VMGD.|
Sentinel-2 satellite images showed persistent strong thermal anomalies in the summit crater during the few days of the reporting period the volcano was not obscured by weather clouds (figure 86). The MODIS-MODVOLC thermal alerts system recorded only occasional hotspots for Yasur during the reporting period. The number of days with recorded hotspots ranged from 0 (October and November 2021; January, March, and July 2022) to 3 to 6 during other months. A high of 4 pixels was recorded on 12 April. In contrast, the MIROVA (Middle InfraRed Observation of Volcanic Activity) system recorded numerous hotspots during the year beginning in February 2022 (figure 85).
Strong sulfur dioxide plumes were often detected by the TROPOMI instrument (figure 87) on the Sentinel-5P satellite (i.e., those plumes exceeding 2 Dobson Units). The number of days with plumes was highest during November and December 2021 (most days) but dropped to one day each for July and August 2022.
Geological Summary. Yasur has exhibited essentially continuous Strombolian and Vulcanian activity at least since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Located at the SE tip of Tanna Island in Vanuatu, this pyroclastic cone has a nearly circular, 400-m-wide summit crater. The active cone is largely contained within the small Yenkahe caldera, and is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. The Yenkahe horst is located within the Siwi ring fracture, a 4-km-wide open feature associated with eruption of the andesitic Siwi pyroclastic sequence. Active tectonism along the Yenkahe horst accompanying eruptions has raised Port Resolution harbor more than 20 m during the past century.
Information Contacts: Geo-Hazards Division, Vanuatu Meteorology and Geo-Hazards Department (VMGD), Ministry of Climate Change Adaptation, Meteorology, Geo-Hazards, Energy, Environment and Disaster Management, Private Mail Bag 9054, Lini Highway, Port Vila, Vanuatu (URL: http://www.vmgd.gov.vu/, https://www.facebook.com/VanuatuGeohazardsObservatory/); Wellington Volcanic Ash Advisory Center (VAAC), MetService, PO Box 722, Wellington, New Zealand (URL: http://vaac.metservice.com/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts 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/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).