Report on Yasur (Vanuatu) — 5 May-11 May 2010
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 May-11 May 2010
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2010. Report on Yasur (Vanuatu). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 5 May-11 May 2010. Smithsonian Institution and US Geological Survey.
19.532°S, 169.447°E; summit elev. 361 m
All times are local (unless otherwise noted)
On 11 May the Vanuatu Geohazards Observatory reported that, following an assessment of Yasur during 26-27 April, activity from the volcano remained high. Strong degassing and ash emissions from all three active vents were noted. Ash fell on the E and W parts of the island. New bombs were deposited around the crater rim and in areas near the vents. Explosions were heard and seen from surrounding villages. Satellite imagery and seismic data confirmed strong degassing and explosive activity. The Vanuatu Volcano Alert Level (VVAL) remained at 2 (on a scale of 0-4).
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. 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.