Report on Yasur (Vanuatu) — May 2013

Bulletin of the Global Volcanism Network, vol. 38, no. 5 (May 2013)
Managing Editor: Richard Wunderman

Yasur (Vanuatu) Explosive activity continued into at least early 2013

Please cite this report as:

Global Volcanism Program, 2013. Report on Yasur (Vanuatu). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 38:5. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN201305-257100.

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Yasur

Vanuatu

19.53°S, 169.442°E; summit elev. 361 m

All times are local (unless otherwise noted)


In BGVN 36:05, we reported that on 12 May 2011, the Vanuatu Geohazards Observatory (VGO) reported, based on information collected by the Vanuatu Meteorology and Geohazards Department, that a OMI (ozone monitoring instrument) satellite image showed strong degassing of SO2 from Yasur volcano during the previous week (see map of this island volcano in figure 42 of BGVN 36:05). On 1 June 2011, the Vanuatu Volcano Alert Level (VVAL) was raised from 2 to 3, following increasing explosive activity during May, then lowered to 2 on 13 June (table 3).

Table 3. The Vanuatu Volcanic Alert Level (VVAL) scale for the six volcanoes monitored by Vanuato Geohazard Observatory (Yasur, Lopevi, Ambrym, Aoba, Gaua, and Suretamatai). See figure 43 for Tanna Island hazard map. Courtesy of Vanuatu Geohazards Observatory.

VVAL Description
Lvl.?       Insufficient monitoring to make assessment.
Lvl.0       Normal low-level activity.
Lvl.1       Increased activity, danger near crater only.         
Lvl.2       Moderate eruptions, danger close to the volcano vent, within parts of Volcanic Hazards Map Red Zone.
Lvl.3       Large eruption, danger in specific areas within parts of Volcanic Hazards Map Red and Yellow Zones.    
Lvl.4       Very large eruption, island-wide danger (including areas within Red Yellow and Green Zones).
Figure (see Caption) Figure 43. Tanna Island volcano hazard map. Key: red = high hazard; yellow = medium hazard; and green = low hazard. Courtesy of Vanuatu Geohazards Observatory.

During the week of 7 12 July 2012, VGO observed that explosive activity at Yasur became stronger and more frequent, and shifted from Strombolian to sub Plinian. Bombs ejected from the vents fell in the crater, around the summit area, and on the tourist walk and parking area (within the red zone, figure 43). The explosions were heard, felt, and observed from nearby villages and schools. Activity at all three volcanic vents was characterized by degassing, ash emissions, and ejection of bombs. On 13 July 2012, the Alert Level was raised to 3.

VGO reported an OMI satellite image on 1 April 2013 showed diffuse SO2 from Yasur. Explosive activity increased on 2 April 2013, with explosions becoming stronger and more frequent, and continued to slightly increase through 28 May. Bombs again fell around the summit area, the tourist walk, and the parking area. Moderate ash emissions and ashfall occurred on 2, 4, and 5 April, and 5 and 8 May 2013. Photos included in the report showed dense white plumes on 23 and 24 May. The Alert Level remained at 2 (on a scale of 0 4).

Volcano Ash Advisory Centre (VAAC) reports on Yasur. In many cases the VAAC lacked any satellite data and in cases where they did have data they frequently were unable to detect the plume or in other cases could not detect ash in the plume (table 2).

Table 2. Yasur volcano aviation reports (VAAs, Volcanic Ash Advisories) for the time interval 11 January 2009 to 10 June 2010. In many cases the information sources were the Vanuatu Geohazard Observatory (VGO). On 11 January the source was an AIREP, an aircraft report. Data provided courtesy of the Wellington Volcanic Ash Advisor Centre (VAAC).

Date (time UTC) Info Source (type of observation) Details Altitude (km) Drift or cited wind direction
11 January 2009 AIREP Plume sighted over volcano by aircraft (to ~4 km altitude, drifting SE). Ash not seen by VAAC analysts in satellite data. ~4km SE
29 May 2010 VGO Observatory reported plume, however no satellite image was made. ~2km Winds NE
30 May 2010 VGO Observatory reported plume, and a volcanic ash cloud was captured with a Modis image. ~2km Winds E
31 May 2010 VGO Observatory reported plume, and a volcanic ash cloud obscured the satellite image. ~2km Winds NE
1 June 2010 VGO Observatory reported plume, and a volcanic ash cloud obscured the satellite image. ~2km Winds N
2 June 2010 VGO Observatory reported plume, and a volcanic ash cloud was unidentifiable on satellite image. ~2km Winds N
3 June 2010 VGO Observatory reported plume, and a volcanic ash cloud was unidentifiable on satellite image. ~2km Winds E/NE
4 June 2010 VGO Observatory reported plume, and a volcanic ash cloud was unidentifiable on satellite image. ~2km Winds NE
5 June 2010 VGO Observatory reported a plume, and a volcanic ash could was unidentifiable on satellite image. A remark was made suggesting volcanic eruption may be easing. ~2km Winds NW
6 June 2010 VGO Observatory reported a plume,and a volcanic ash cloud was unidentifiable on satellite image. ~2km Winds NW
7 June 2010 VGO Observatory reported a plume, and satellite image was unavailable. ~2km Winds NW
8 June 2010 VGO Observatory reported a plume, and satellite image was unavailable. ~2km Winds NW
9 June 2010 VGO Observatory reported a plume, and satellite image was unavailable. ~2km Winds
10 June 2010 VGO Observatory reported a plume, and that no volcanic ash was visible on satellite image. ~2km Winds NE

Satellite Thermal Alerts. The MODIS/MODVOLC satellite thermal alert system has shown least 1 to 10 alerts each month over Yasur since the beginning of 2011. A lava lake has existed at Yasur for many years.

References. Allen, S.R., 2005, Complex spatter and pumice rich pyroclastic deposits from an andesitic caldera forming eruption:The Siwi pyroclastic sequence, Tanna, Vanuatu, Bulletin of Volcanology, v. 67, pp. 27 41.

Calmant, S., Pelletier, B., Lebellegard, P., Bevis, M., Taylor, F.W., and Phillips, D.A., 2003, New insights on the tectonics along the New Hebrides subduction zone based on GPS results, Journal of Geophysical Research, v. 108, no. B6, pp. 2319 2339.

Carnay, JN., and MacFarlane, A, 1979, Geology of Tanna, Aneityum, Futuna and Aniva, New Hebrides Geological Survey Report 1979, pp. 5 29.

Métrich, N., Allard, P., Aiuppa, A., Bani, P., Bertagnini, A., Shinohara, H., Parello, F., Di Muro, A., Garaebiti, E., Belhadj, O., and Massare, D., 2011, Magma and Volatile Supply to Post collapse Volcanism and Block Resurgence in Siwi Caldera (Tanna Island, Vanuatu Arc), Journal of Petrology, v. 52, no. 6, pp. 1077 1105; DOI: 10.1093/petrology/egr019.

Nairn, I.A., Scott, B.J., and Giggenbach, W.F., 1988, Yasur volcanic investigations, Vanuatu September 1988, New Zealand Geological Survey Report 1988, pp.1 74.

Pelletier, B., Calmant, S., and Pillet, R., 1998, Current tectonic of the Tonga New Hebrides region, Earth and Planetary Science Letters, v. 164, pp. 263 276.

Geologic Background. Yasur, the best-known and most frequently visited of the Vanuatu volcanoes, has been in more-or-less continuous strombolian and vulcanian activity 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, this mostly unvegetated pyroclastic cone has a nearly circular, 400-m-wide summit crater. Yasur 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, horseshoe-shaped caldera 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: Vanuatu Geohazards Observatory, Department of Geology, Mines and Water Resources of Vanuatu (URL: http://www.geohazards.gov.vu); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov); MODIS/MODVOLC Thermal Alerts System, Hawai'i Institute of Geophysics and Planetology (HIGP), School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/); and Wellington Volcanic Ash Advisory Centre (VAAC), Meteorological Service of New Zealand Ltd (MetService), PO Box 722, Wellington, New Zealand (URL: http://www.metservice.com/vaac/, URL: http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html).