The eruption of Eyjafjallajökull volcano in 2010 led to the closure of most of the major airports in Europe. And that was because of the large amount of the extremely fine ash that was dispersed high in the atmosphere at the level that most aircraft fly.
The eruption style of Eyjafjallajökull is a particular type that we call phreatomagmatic. And that’s driven by hot molten rock or magma rising to the earth’s surface and encountering external water, super-heating that to steam and in the process producing a lot of very fine ash.
Perhaps the most significant volcanic event that occurred during the history of mankind was the eruption of Laki volcano in Iceland in 1783. The eruption lasted for about 8 months, and it released over 120 megatonnes of sulphur dioxide into the atmosphere. That caused a lot of deaths through poisoning, but it also then led to what is known as a volcanic winter, where for a period of 2 or 3 years the summers were actually like winters, and it’s estimated that that particular event caused the death of perhaps up to 6 million people.
The question of whether or not the earth would be better off without volcanos is a very interesting one; it’s double-edged sword. On the one hand with the increasing development of settlements, towns and cities closer and closer to volcanos there is the potential for a major disaster. However, the other side of volcanos is that they are the source of many important natural resources; a most obvious one is geothermal energy. As we are looking for greener sources of energy, geothermal energy generated by the heat in the ground underneath volcanos offers a huge source of energy.
In addition, of course the soils that develop from the bedrock of volcanic eruption products is usually very fertile, and we have a very good example of this in Western Victoria