Toba or Not To Be
Researching volcanoes at the moment for my studies and it got me thinking about somewhere I went in Indonesia a while ago. Lake Toba is a caldera (a crater lake caused from the collapse of a volcano and its magma chamber after a massive eruption) in the North of Sumatra. Toba is indeed massive; I mean really, really, really big: the island in the middle of the lake is nearly the size of Singapore and the lake itself stretches out to 100 kilometres in length making it he largest crater lake in the world. Actually it is four craters from four massive eruptions all joined together but that doesn’t take away from the sheer scale of the place. Hardly surprising when you think about it that it is thought the last eruption around 75,000 years ago nearly wiped us out.
Anyway I had to write something to explain the good and bad in volcanoes and I liked it so thought I’d share it here. As I said before I am studying in isolation here so any feedback, advise, criticism and extra input you can may be able to provide will be greatly received.
By the way the picture above is not Lake Tobe but Lake Maninjau, another large caldera from another large, explosive eruption just to the south of Toba. I haven’t had time to scan up my Lake Toba slides yet and anyway it is just too damn big to get the I’m living in a volcanic crater feel across that Maninjau does. I spent a long time in this area of Sumatra; loved it there: lovely place, great scenery, great people. Hard to believe it was once so hellish and hostile.
ARE VOLCANOES GOOD OR BAD?
Volcanoes are one of the most impressive features detailing the dynamic nature of out planet. There are approximately five hundred active volcanoes in the world at this time, the majority of which are to be found on along the edges of the tectonic plates that make up the Earth’s crust particularly around the Pacific Rim or the “ring of fire” where the Pacific plate and the smaller Cocos and Nasca plates are being sub-ducted under the adjacent continents and the lithosphere is being melted, re-absorbed into the Mantle where it rises again to the surface as volcanoes peaks and islands. There are some volcanoes however, like Hawaii, that are to be found away from the plate margins over what are thought to be convectional “hot spots” in the Earth’s mantle. These super heated uprises of molten magma can force their way to the surface in the centre of the plates, perhaps by exploiting a weaker or thinner crust, far from any of the usual forces and systems associated with volcanology.
For the people of Hawaii, the question of whether volcanoes are good or bad has to be tempered, of course, by the simple truth that without the existence of volcanoes in that part of the Pacific Ocean the islands they call home would not be there. In this case, at least, volcanoes can be assumed to be a force of good on the planet as they have created land that is able to be exploited by human being for habitation.
Indeed 95 percent of the rocks on the planet are volcanic in origin and all other rocks types are derived via erosion, weathering or metamorphosis under heat or pressure from these original igneous rocks. Most of the rock being created by volcanic eruptions however is not visible to us as it occurs under the sea at constructive plate margins where continental plates are moving apart and magma swells up to fill the gaps. Countries like Iceland owes its existence to just such volcanic activity. According to the University of Iceland the east and west coasts of the country are growing apart at a rate of around two centimetres a year as the Eurasian continental plate and North American continental plate slowly move away from each other. The volcanoes and lava flows that make up this nation are merely the same processes that happen all along the Mid-Atlantic Ridge but have managed to grow to such a hight that they have risen above the waves and allow us to witness new crust being formed. Though it could be argued that Iceland is still “a work in progress” and it future remains unpredictable there are many advantage to living in such a place.
Not only is the amazing volcanic scenery of Iceland a major draw for the lucrative tourism industry in the 21st Century but many traditional and modern technologies use the soil, rocks and energy of the landscape for profit. In fact all over the world people have always been drawn to volcanic landscapes, despite the risks (some known and others not), for the benefits they can provide.
Firstly volcanoes create land that is very fertile for farming: the ash that is ejected in a volcanic eruption is rich in minerals and since pre-history people have lived and farmed on land surrounding volcanoes. In modern times, though agriculture is still the main beneficiary, people are also just as likely to make a living from the harnessing of geothermal energy for electricity production. For example Iceland is able to generate 80% of its energy needs with reliable and clean geothermal and hydro (water) power.
The hot water generated in areas of volcanic activity is also used in agriculture and aguaculture (where the hot water is piped from underground to keep fields and fish farms above freezing) as well as for the heating of dwellings. In some countries it is also an essential part of social and cultural identity as the ancient hot baths of Roman Italy and the many hot-spring resorts or Onsen in modern-day Japan attest. The quintessential volcano known as Mount Fuji is also an important cultural icon in Japan.
Of course were Mount Fuji to erupt the results would be more serious than a lack of up to date postcards and pretty views. An estimated 12.5 million people live near this archetypal volcano and a Japanese government report in 2004 costed the damage of an eruption, similar in scale to the last Mount Fuji eruption in 1707, at over 27 billion US Dollars. The disruption to modern Tokyo caused by dust and and ash would be immense causing transportation and electricity system collapse as well severe heath risks from breathing in the air-borne dust particles.
Volcanic eruptions can cause problems in the natural world too. The Mount Pinatubo eruption in the Phillipines in June 1991 not only destroyed the rice harvest that year but the new landscape made planting the 1992 crop impossible. The situation was made worse by heavy rains and storms, caused by a volcanically-invigorated monsoon leading to mudslides of volcanic debris, called lahars, that buried towns and forests. The resulting stagnant water often became contaminated leading to an increase in diseases and serious outbreaks of malaria. The largest effect of the eruption however was the cooling of the global temperature caused by the 4,800 kilometre wide cloud of ash and other particles the eruption threw 32 kilometres high into the atmosphere. This “Pinatubo effect” may even have delayed some of the adverse effects of manmade global warming which could be seen as a lucky side-effect, The detrimental effect of suspended sulphur particles in the upper atmosphere may also unfortunately have caused an acceleration in the depletion of the already damaged ozone layer however.
In summary volcanoes are a dichotomous phenomena: there are good and bad aspects to their existence for humans on the planet. Of course they provide the land we live upon and make the soil richer to help us feed ourselves and recently we have learnt to exploit their store of precious metals and their heat energy to finance and power our modern lives. But over all, it cannot be said that volcanoes are good for humans life on this restless planet. There are very few totally extinct, and thus totally safe, volcanoes on the Earth. While old volcanic activity has created land forms and opportunities for us, from castles in Edinburgh to clean, healthy mineral water in France, even as tourists flock to Mount Fuji (the most visited national park in the world) or holiday on Lake Toba in Sumatra there is no guarantee that these scenes of serenity and adventure will forever remain peaceful. It is believed by some scientists that the massive eruption that created the Toba caldera about 74,000 years ago also wiped-out almost all life on the planet including a more-than-significant reduction in the human being that were living on the world at that time. Some estimates put the number of humans that survived the eruption at a mere 1,000 breeding pairs. Other scientists think the resourcefulness of the human species survived very well however despite ejecta, that travelled on the monsoon winds, being able to blanket distant India in as much as six metres of dust and ash and the six to ten year long volcanic winter created by the the nearly 3,000 cubic kilometres of debris that was thrown into the atmosphere, blocking out the sun, and accelerating the onset of the last ice-age. If these suppositions are correct then the lack of diversity in human DNA can be explained by this tightening of the gene pool, or bottleneck as it is called. After millions of years of evolution it would be usual to find more differences than similarities among humans and yet homo-sapians are apparently more similar across continents and races than individual chimpanzees are within the same troop.
Indeed it appears we are extremely lucky to be here at all after that huge eruption millennia ago. But the planet does not owe us our existance and there are still other super volcanoes such as Ngorongoro Crater in Tanzania and the worrisomely active and overdue eruption expected at Yellowstone Park supervolcano in the United States that if, and more importantly, when they erupt again could seriously affect population levels or even lead to the extinction of all humans and a lot of other life too.