Explosivity

Seeing a volcano erupt is a truly awesome sight, but there are some volcanoes you wouldn’t want to be standing too close to when they do. In fact, with some, you wouldn’t want to be standing anywhere near when they explode. So volcanologists have developed a scale that helps them measure just how explosive they are!

This is called the Volcanic Explosivity Index (VEI) and measures several things: how high the shattered volcanic material is thrown into the air, how much material is erupted and how quickly it comes out.  The VEI scale goes from 0 to 8, but it is designed so that a change in the scale by 1 is an increase in 10 in eruption size. In very simple terms, a VEI 1 eruption throws out about enough material to fill a large football stadium (about 1 million cubic metres of ash), while a VEI 8 eruption throws out enough material to bury the whole of the United States with 10 cm of ash (about 1000 cubic kilometres of ash).

For Volcanoes Top Trumps, what we decided was that the most interesting stat to compare was the largesteruption VEI that each of our volcanoes has had. Thinking about where to stand to watch an eruption…VEI 1 could be safely seen from about two football pitches away. A VEI 5 would really only be safe to watch on the television, but a VEI 8 would be so big that it would be impossible to film, apart from in space…!