Mount Yasur

Erupting several times an hour, and you can stand there

Mount Yasur, on Tanna Island in Vanuatu, stands only 361 metres above the sea on the coast near Sulphur Bay, and it has been erupting almost without a break for several hundred years. The cone is largely bare of vegetation around a nearly circular summit crater 400 metres across. Its eruptions, often several an hour, are Strombolian or mild Vulcanian, throwing out volcanic bombs, some as far as the forested slopes below the summit, and at times there has been a lava lake at a central vent. A monthly activity report counted an average of 500 explosions a day at normal levels. The name comes from the Kwamera word iasur, meaning volcano.

Yasur sits where the eastward-moving Indo-Australian Plate is subducted under the westward-moving Pacific Plate, a slab that can be traced to a depth of at least 250 km. Its glow is thought to be what drew Captain James Cook, on the first European journey to Tanna, in 1774, and it is called the lighthouse of the Pacific. In October 2022 the International Union of Geological Sciences put the Yasur-Yenkahe volcanic complex on its list of 100 geological heritage sites around the world, for its 800-year-long eruption.

The summit can usually be approached on foot, and the volcano is a major Vanuatu tourist attraction. The Vanuatu Geo-Hazards Observatory monitors it, and the government sets alert levels from 0 to 5 with the warning that an eruption may occur at any level. Ash clouds have reached 2,000 metres, the volcano has been associated with a tsunami, and there have been at least three deaths at Yasur in recent years. Check the level on the day before going up.

The mountain is sacred to the John Frum movement, whose followers revere a deified messenger who foretold that American forces would bring wealth to the island, and believe he lives inside Yasur with his countrymen. The village of Sulphur Bay, the centre of the movement, claims the volcano as part of its territory.