Iceland's fireworks warn of devastating supervolcano
Every so often the Earth chooses to remind us that we really aren't in control of this planet. The volcanic eruption in Iceland, which began on Wednesday, is just such a reminder. As ash spews out across northern Europe, grounding all flights across Scandinavia and the UK, we begin to realise how powerless we humans are.
But as volcanic eruptions go, the fireworks on Iceland are small fry. Scientists rank volcanoes according to how explosive they are, using the volcanic explosivity index (VEI), which goes from zero to eight.
Like the scale used to measure earthquake size, the VEI is logarithmic -- meaning that a volcano with a VEI of five is 10 times more powerful than one with a VEI of four.