Vanuatu: alert level raised for Yasur

The stratovolcano Yasur on Tanna Island in Vanuatu is highly active: the Global Volcanism Program notes that Yasur has ‘been in more-or-less continuous strombolian and vulcanian activity since Captain Cook observed ash eruptions in 1774’. Cook himself compared the volcano to Stromboli because of its continuous lava fountaining. Yasur is also highly accessible, and is one of Vanuatu’s most important tourist attractions.

Early last month satellite sensing revealed strong degassing from Yasur, and local residents reported strong explosions. The hazard level for Yasur was then at 2 (on a scale of 0-4, where 4 is the highest). In bulletin no. 1, issued on 12 May, the Vanuatu Geohazards Observatory noted that this strength of degassing ‘is not common for this volcano’ , possibly indicating ‘magma intrusion in the volcano conduit’, and warned of further potential explosive activity. The bulletin described the then level of activity at Yasur as ‘a minor eruption phase with persistent strong explosions that could be heard and felt’.

A geohazards team from the Vanuatu Geohazards Observatory carried out further assessments on 31 May and 1 June. In its bulletin no. 2 of 1 June 2011 the Observatory reports a ‘moderate to large eruption’ of Yasur under way with ‘strong explosions and ash bombs/emissions from all three active vents’. The hazard level has therefore been increased with effect from 1 June to level 3. Access to Yasur has been closed, with a 500-metre-radius exclusion zone in place around the volcano.

[Image of Yasur above by Verity Borthwick, taken on 24 February 2009. Reproduced here under a Creative Commons licence.]

News
Vanuatu officials raise alert level over Mt Yasur volcano – Radio New Zealand International, 2 June 2011
Vanuatu volcano access closed after explosions – Australia Network News, 3 June 2011

Information
Global Volcanism Program: Yasur – summary information for Yasur (0507-10=)
Vanuatu volcanoes and volcanics – information from the USGS Cascades Volcano Observatory
Vanuatu Geohazards Observatory – home page for geohazards monitoring in Vanuatu