Home Engineering The dark side of technology
European effects from Icelandic volcanoes
Because for the UK, the Icelandic eruptions are the ones most likely to cause a local effect, I will briefly review events that have produced European problems in recent times. Iceland is an active region with at least 30 separate volcanoes. A major eruption event in 1783 from the one named Laki produced a thick fog and ash over Europe, causing cooling, crop failure, and famine; as already mentioned, it also triggered the unrest leading to the French Revolution.
A different Icelandic volcano, Eyjafjallajokull (besides being unpronounceable in English, and therefore rarely discussed verbally), erupted in 2010 and put out fine ash that closed North European air traffic. The caution in blocking air traffic was due to the danger from the fine ash that is produced when volcanic ejections interact with water and ice, as from the Icelandic glaciers. The water and steam fragment the large lumps of ejected material into very fine particles of ash. This dust is then supported for a long time in the atmosphere, often at the level of air traffic. Because it is so fine, it is very difficult to detect, it is not as visible as a cloud of smoke. When the ash is sucked into jet engines, it is melted into glass droplets in the intense flame zone (which approaches 2000°C). However, as the droplets leave the engine, they cool down to, say, 1000°C, then stick to the engine components in the form of glass. There have been previous dramatic examples where the buildup of glass has resulted in jet engine failure and plane crashes.
Since the atmospheric magma particles are finely dispersed, they are not easy to detect, so it is tempting to assume the problem is negligible. Nevertheless, a modern jet can push some 60,000 kg of air through the engine each hour. (Because planes are heavy, they need a lot of energy to keep going.) So even if the dust is only at very modest concentrations of one part per thousand of the mass of the air, and just one per cent of it sticks on the engine surfaces, then the glass buildup would be at a rate of kilograms per hour (i.e. guaranteed engine disaster). Interestingly, this is an example of a problem caused by improved technology, as in earlier aircraft the internal engine temperatures were not high enough to form glass droplets. In 2010, closing the North European air traffic may have appeared to be a non-event, but it cost the global economy some $5 billion. Nevertheless, the costs are far less than the indirect effects of air crashes.
Air control policy has altered (possibly influenced by the economic impact), and it is assumed that there may (may!) be less of a hazard than was assumed in 2010. However, if there is a repeat eruption, my guess is that I will be among an increased number of Eurostar train users.
Another interesting Icelandic volcano is Bardarbunga (also hard to pronounce), which is beneath an ice cap. The cap is steadily melting due to a significant rise in temperature at these latitudes. Because the surface is lifting at one foot per year in some regions, glacier weight is reduced over the cap of the volcano. Inevitable consequences are more eruptions and local flooding, and of course the potential to have fine ash ejection into the atmosphere. Continued monitoring is in progress, not least as Icelandic volcanic activity has rapidly increased within recorded human history by some 30 times.
|< Prev||CONTENTS||Next >|