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Yasur, on Tanna island, Vanuatu, is one of the most famous volcanoes in the world.
www.pocruises.com.au summer/autumn 2011
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Words: roderick eime Photos: Mick Fogg
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ver An incurable cruiser marvels at one of nature’s greatest spectacles.
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languid haze hangs over the smouldering caldera. Somewhere deep in the bowels of this flattened mountain is a bubbling cauldron of molten lava that explodes sporadically in a climax of scalding-hot liquid rock. I watch wisps of smoke issue from a mysterious source; then, suddenly, a shockwave reverberates through the mist, heralding the inevitable…KER-BANG! I’m witnessing one of nature’s greatest spectacles: the eruption of an active volcano on the island of Tanna in Vanuatu. Called Yasur, it is perhaps one of the most famous volcanoes in the world, if only because it is so safe and accessible. Yasur’s ear-splitting broadside is followed by a vivid spray of lava that, at night, resembles a Roman candle. Just as you stand agog at this display and the thunderclap dissipates, all around you is the sound of ‘plop’, ‘plop-plop’, ‘plop’, as patties of magma splatter on the ground just metres away. “Safe?” I hear you ask. Yes, the popular viewing spot is shielded from falling debris, but if you even look like wandering off the path, your guide will howl in warning. Vanuatu, formerly the New Hebrides, is one of the world’s volcano-watching hotspots, with six active locations: Yasur, Lopevi, Kuwai, Ambae, Ambrym and Gaua. Apart from Yasur, any of these islands could again erupt. Gaua awoke in 2009 after several years of dormancy and every one has a history of eruptions over the past few decades. www.pocruises.com.au summer/autumn 2011
Despite its fame, Yasur rates barely a dummy-spit on the tantrum scale for volcanoes. Volcanic activity is measured using an explosive rating similar to the Richter Scale for earthquakes. The Volcanic Explosivity Index (VEI) scores eruptions from zero to eight. Yasur is a two on this scale, and is also called ‘Strombolian’ because of its resemblance to the Italian volcano near Sicily that has bubbled away consistently for 20,000 years or more. Thankfully, we haven’t seen any eights recently, the last one being Lake Taupo in New Zealand some 26,000 years ago. Of the recent big ones, Mount St Helens (1980) rated a five, Krakatau (1883) a six and 1991’s whopping Mount Pinatubo, in the Philippines, also a six. Iceland’s Eyjafjallajökull, which brought European air traffic to a grinding halt, rated a modest four, the same as Rabaul’s Mt Tavurvur (1994). The largest eruption to be recorded and witnessed was that of Mount Tambora in Indonesia in 1815. This seven-rated quake is known to have upset climatic conditions as far away as Europe and the United States, with a massive dust cloud smothering that year’s summer and causing many crop failures. Interestingly, Keith Briffa, a palaeo-climatologist at the University of East Anglia in the UK, also suggests that the historic term Dark Ages actually refers to a catastrophic climate-change event caused by a huge seven-plus eruption around 533–536AD, which in turn caused numerous social and political events that shaped our civilisations. Environmental scientist Mick Fogg regularly engages with tourists and travellers who are seeking explanation of the natural world around them. He has explored many of the volcanoes in the South Pacific.
VOLCANO TALK Understanding the common terms ● Basalt is a hard, black volcanic rock with about 52 weight per cent silica (SiO2). ● Calderas are large, usually circular depressions at the summit of a volcano, formed when magma is withdrawn or erupted from a shallow underground magma reservoir. ● Fumaroles are vents from which volcanic gas escapes into the atmosphere. ● Lahar is an Indonesian word for a mud flow, particularly one on an active volcano. ● Magma is molten rock containing liquids, crystals and dissolved gases. Magma forms within the upper part of the Earth’s mantle and crust, becoming lava on the surface.
next to go?
One of Europe’s largest bookmakers, Paddy Power, is taking bets on the next volcano to erupt with a Volcanic Explosivity Index (VEI) of three or greater.
Seulawah Agam (Indonesia) 5/4
Vesuvius (Italy) 12/1
Stromboli (Italy) 20/1
Unzen (Japan)
Ulawun (PNG)
12/1
Cascade Range (USA) 20/1
Katla (Iceland)
Sakurajima (Japan) 18/1
Eyjafjallajökull (Iceland) 5/2
Santorini (Greece) 14/1
Taal (Philippines) 16/1 Etna (Italy) 28/1
Galeras (Colombia) 15/8
Colima (Mexico) 14/1
Avachinsky (Russia) 22/1
www.pocruises.com.au summer/autumn 2011
3/1
5/1
Rainier (Washington, USA) 16/1
Chaitén (Chile)
28/1
Yellowstone (USA) 50/1 Teide (Canary Islands, Spain) 6/1 Mauna Loa (Hawaii) 10/1
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Photograph by Mick Fogg
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“Volcanoes are always a source of great interest for passengers aboard cruise ships,” says Mick, “and my lectures on vulcanology are some of the most popular. “I first explain the difference between the two main types: explosive and effusive. As the names suggest, one blows up while the other just oozes. The Hawaiian Islands are famous for their effusive volcanoes, such as Kilauea. You can actually get quite close to the lava, which comes out from cracks in rock like red-hot toothpaste. The ones on Vanuatu are all explosive, characterised by what we call ‘energetic ejection of pyroclastic material’. “In either case, a volcano is always caused by the same thing, which is magma and gasses exiting a vent (or crack) in the Earth’s surface under pressure. The size and type of the volcano is then determined by other geological factors. We get shield volcanoes, strato-volcanoes, cinder cones or lava domes, depending on the temperature, gas pressure, lava thickness or tectonic-plate activity beneath the vent.” Apart from the scientific attraction of vulcanology and the awe-inspiring spectacle of an eruption in full force, volcanoes also enter the realm of fiction and romance.
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Left: Mount Tavurvur in Rabaul, PNG, devastated the town in 1994 and continues showering the ruins with ash.
Opposite page, top to bottom: Mount Bromo and Mount Semeru on the Indonesian island of Java.
You can get quite close to the lava, which comes out from cracks in rock like red-hot toothpaste. Pulitzer-Prize-winning author James Michener introduced his many readers to the fictional island of Bali Ha’i in his acclaimed work Tales of the South Pacific. Bali Ha’i is, in real life, Vanuatu’s volcanic island of Ambae (though this mountain wasn’t seen in the film version of the novel). Michener was intrigued by the way the volcano, when viewed from his barracks on Espiritu Santo, seemed to appear and disappear behind a cloak of mist. The timid island then became the redoubt of Michener’s character Bloody Mary and a famous refuge for beautiful women trying to escape the unwelcome attention of lusty American GIs. Volcanoes are, for many, the ultimate expression of our planet’s natural fury. To see one in action, up close, is a thrill no theme park can deliver.
volcano sightings ●
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Ambryn Ships sail past or nearby this volcano en route to north Vanuatu port calls, including Champagne Bay, Luganville, Wala and Pentecost. Tanna Ships pass this volcano when sailing from Port Vila to Mystery Island in Vanuatu, and from the Fijian Islands back to Port Vila or Mystery Island. www.pocruises.com.au
www.pocruises.com.au summer/autumn 2011