Yasur Volcano – Yenkahe Caldera

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Volcano Fact Sheet Yasur Volcano – Yenkahe Caldera Description Yasur, located at the SE tip of Tanna Island, is a mostly unvegetated 361-m- high scoria cone with a nearly circular, 400-m-wide summit crater. Yasur is the most frequently visited of the Vanuatu volcanoes. It has been in more-or-less continuous activity since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. (www.volcano.si.edu) Type Yenkahe hill Safety Yasur is a basaltic scoria cone that This huge block of ground beside Yasur Bombs can land in any zone at any typically has up to five active vents. has been pushed up, probably by time. The only way to avoid all risk of These produce a combination of two magma underground. bombs is to stay off of Yasur. eruption types Hot springs Stay out of the permanent exclusion Strombolian - bubbles of glowing Groundwater heated by the magma zone – the danger is extreme magma burst, spraying bombs of lava comes up fractures around the The exclusion zone may be into the air Yenkahe hill. extended - during periods of larger or Vulcanian – explosions that burst Earthquakes and ground movement more frequent explosions to include through a blocked vent, generating Zone A, or to include Zone A & B. showers of bombs and also clouds of Earthquakes in this area have raised fine ash, which blow downwind the Yenkahe hill and Port Resolution Check which zone(s) are closed in Harbour more than 20 m during the the latest bulletin - click on ‘Tanna’ at: Erupted Magma is up to 1000°C and past 300 years. http://www.geohazards.gov.vu/ bombs remain very hot for up to an Flying bombs are always a danger hour from eruption. Ash is not hot. Cause Wear a hard hat – it will help protect Yasur’s summit is 361 m above sea Vanuatu volcanism is caused by you, but it will not stop larger bombs. level and the crater is 600 m across at subduction of the Indo-Australian plate its widest point. below the Pacific plate under Vanuatu. Watch for bombs in the air - especially after explosions. Stand still unless you Volcanic history A large magma chamber is located a few km below Yenkahe caldera, see bombs that are not moving Yasur is the youngest of a group of feeding Yasur and pushing up left/right or up/down – these are Holocene volcanic centres constructed Yenkahe hill and ajacent areas. coming towards you, and you should inside a larger volcanic caldera. avoid them. Monitoring Yenkahe Caldera Bombs fly very fast - even though There are a seismograph, two The Yenkahe caldera is a 4-km-wide, they look to move slowly at first. The cameras and a microbarometer time from an explosion to bombs horseshoe-shaped depression that stationed at Yasur, monitored remotely collapsed during two large eruptions landing at the rim is often only a few by VMGD in Port Vila. The data and seconds. that blanketed almost all of southern photos can be seen at: Tanna in thick ash and scoria. This Falling into the crater – beware deposit forms the cliffs along the SE http://www.geohazards.gov.vu/ that the edge of the crater is slippery and S coasts. and unstable. .

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