Bang Goes Life on Earth When Supervolcano Blows
Right in the middle of Indonesia's highly active earthquake zone is a supervolcano that almost extinguished the human race when it last erupted. Graham Lees looks into the possibility of it being jolted into action
by Graham Lees

As intense as the tragedy of the Boxing Day tsunami was, the earthquake that spawned the waves and the subsequent tremors have some volcanologists worrying that something even worse could be brewing beneath the surface of the Indonesian archipelago.

For, sitting plum in the middle of the quake-hit region is Lake Toba, a supervolcano so vast that the last time it blew its top, about 70,000 years ago, the fallout triggered a volcanic winter and almost exterminated the human race, scientists say. The force of its eruption ripped a hole so big in the north Sumatran landscape opposite Malaysia that it resulted in a lake which today measures 100 kilometers by 30km. A 45-km-long island in the lake is the "plug'' that formed over the volcano after its molten furnace cooled down.

Scientists have for years warned that it is inevitable that one of the world's supervolcanoes - so-called because of their size and capacity to cause enormous destruction- will erupt again. Many experts now directly link major quakes with volcanic eruptions.

Since the December 26 quake, which measured a near-record 9.1 magnitude on the Richter scale, there have been numerous volcanic disturbances - most on Sumatra and within roaring distance of Toba.

Raymond Cas, an expert on the earth's fragile crust and director of a volcanology research center at Australia's Monash University, told Weekend Standard: ``Toba is dormant but cannot be classified as extinct, and it still has an active geothermal system.''

But as Indonesia's overstretched authorities struggle to cope with minor eruptions along Indonesia's ``ring of fire'' fault line, Toba is being relegated to a low-alert status.

Surono, a senior official with the Directorate of Volcanology and Geological Hazard Mitigation, says: ``We are not classifying Toba as an active volcano. We aren't doing any monitoring efforts on Toba now because we believe there is no necessity to do so.''

Cas had earlier warned of an ecological catastrophe if Toba were jolted into action. He has labeled supervolcanoes the biggest threat to life on earth.

``The only greater threat is an asteroid impact from space,'' he said.

Cas concedes that for the moment there appears to be no imminent threat from Toba, but told the Australian media: ``The big problem is a lot of the volcanoes that potentially could erupt are perhaps not monitored to the degree that they should be, and of course we learnt that lesson from the [December 26] tsunami disaster.''

Amazingly, there is no coordinated internationally financed volcano-watching system in place.

``Mostly it's each country on its own,'' Cas said in an interview. ``Countries like Indonesia receive some foreign assistance to improve monitoring and help train scientific staff. More direct foreign assistance would usually kick in during a crisis.''

In the past few weeks Indonesia has put 11 volcanoes under close watch, including the ``son'' of Krakatoa, which caused devastation 122 years ago. Only last week 25,000 people were evacuated from around Mount Talang, south of Toba and only 80km from the city of Padang, population one million, as hot ash spewed into the air.

Indonesia has scores of still-active volcanoes strung out along a half-moon arc thousands of kilometers long, from the northern tip of Sumatra, just south of Thailand, right round to the Celebes Sea and the border with the Philippines.

Indonesia is clearly under stress - both geophysically and financially.

Isya Nur Ahmad Dana, who supervises the monitoring of volcanoes in Sumatra and western Java, says: ``We are not monitoring Lake Toba, and we don't even have any equipment to do the monitoring. We prioritize the monitoring to type-A volcanoes, those that have erupted since 1600.''

But seemingly placid Lake Toba, where children of the Batak tribe swim and tourists flock to view the picturesque scenery, is not isolated from the recent upsurge in earth tremors.

The 8.7-magnitude earthquake of March 28, which killed more than 700 people on the tiny island of Nias, off Sumatra, is only about 200km from Toba. Lesser tremors have rocked the edge of Lake Toba and there have been rumblings on some neighboring volcanoes.

The makers of a two-hour docudrama called Supervolcano - the Discovery Channel and the BBC - were so shocked by the magnitude of the tsunami disaster and subsequent deadly earthquake, they delayed its broadcasting out of respect for the many dead, and because their production is so frighteningly realistic.

For the project, vivid Hollywood imaginations re-awakened a dormant Yellowstone National Park volcano in the United States and engulfed much of the US and beyond in a poisonous ash-filled permanent night of death and destruction.

``Two years ago, when this film was first suggested to me, I didn't know what a supervolcano was,'' BBC producer Ailsa Orr said in a Web site interview. ``But when I did, my reaction was: `This is something we should all know about.'

``We all felt this was an incredibly important story to tell, and I am confident there is nothing in this film I cannot justify.''

The film was shown in Britain only last month.

Since the early 1800s, many thousands of people have been killed in Southeast Asia alone by volcanoes (see panel). Victims included survivors of the blasts who later succumbed to famines caused by climate change and devastated farmland.

The eruption of Mount Pinatubo in the Philippines in 1991 had a global effect on climate. Pinatubo spewed up to 30 million tonnes of sulfur dioxide gas into the atmosphere, which converted it into ozone-damaging sulfuric acid.

Gases and ash formed an earth-enveloping cloud which lowered temperatures globally for up to two years. Pinatubo was blamed for floods in the US and drought in northern Africa.

But Indonesia's Surono adds: ``The recent volcanic activities aren't so special. The shifts and bumps of tectonic plates can trigger volcanic activities or eruptions. But we cannot generalize that an earthquake will certainly trigger an eruption. It is a case-by-case basis.''

Indonesia's string of volcanoes follows a deep undersea trench known as the Sunda-Java line.

``This is where the Indian Ocean tectonic plate is being recycled, like a conveyor belt, back into the earth's interior,'' explains Cas. ``The downgoing plate partially melts at depth and releases volcanic gases and molten rock, or magma, that feeds the line of volcanoes.

``Earthquakes and volcanic eruptions will be an ongoing phenomena.''

Cas insists that the world will one day have to face a supervolcano blowing its top. There will be enormous immediate casualties, but the effects on climate and food production could be more catastrophic to life.

In addition to Toba, there are supervolcanoes in New Zealand, South and North America and Italy.

Adds Cas: ``Sooner or later one is going to go off.''

Copyright 2005, The Standard

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