Report on Yasur (Vanuatu) — 1 June-7 June 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
1 June-7 June 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Yasur (Vanuatu). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 1 June-7 June 2011. Smithsonian Institution and US Geological Survey.
19.532°S, 169.447°E; summit elev. 361 m
All times are local (unless otherwise noted)
On 1 June, the Vanuatu Geohazards Observatory raised the Alert Level for Yasur to 3 (on a scale of 0-4) following increasing explosive activity during May. Access to the volcano was closed and a 500-m zone around the volcano was restricted. The Geohazards team noted strong explosions from all three active vents along with ash emissions and bomb ejections during 31 May-3 June. Bombs fell around the crater rim and explosions were heard and observed from nearby villages.
Geological Summary. 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. 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, 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.