Here at Volcano Top Trumps HQ, we wanted to come up with an exciting category that described a volcano’s potential for devastation.

Some of our volcanoes, in particular the more explosive ones, haven’t erupted for a little while. Other volcanoes, such as Mount Etna haven’t had really big eruptions for a while either. In the mean time, towns and cities have grown in their shadows, and countries have become more and more dependent on infrastructure (like airports, roads, water and power supplies) which could be vulnerable to volcanic hazards.

So we decided to come up with a category that tries to measure this…!

As our game is based on official stats and facts, we couldn’t just guess at this category…so being slightly geeky scientists – we came up with a way of defining a volcano’s devastation potential.

We wanted to make this fair, so it had to be simple. We limited ourselves to the following bits of information about a volcano, which are widely available:

- The Maximum Eruption Size (
**VEI**)_{MAX} - The number of people living within a certain distance, which we then rank the volcanoes by (
**Pop**)_{R} - The number of times it has erupted at its Maximum VEI (
**VEI**)_{COUNT}

We also tried to evaluate a volcano’s:

- potential for ‘Global Impact’ (
**I**)

As we know already, VEI is related to the eruption size. The VEI scale is almost logarithmic, so that each increase in VEI by 1, means a 10x more powerful eruption. Volcanoes with eruptions greater than or equal to VEI 6 are quite likely to put a lot of ash, aerosols and other particles high up into the atmosphere. This means that ash can stay in the air for a long time, and go far away from the volcano. These eruptions also have the potential to change global climate.

That is why we decided that volcanoes with VEI 6 or greater would have a global impact factor of 10 for VEI6, 100 for VEI7 and 1000 for VEI8.

We compiled the number of people living around the volcano, and then ranked the volcanoes. We rank them, rather than using the actual population number, as this number can vary over many orders of magnitude, from tens to millions . We do this so that we can more easily compare the volcanoes in the game.

We are really interested in VEI_{COUNT} as this tells us about the volcanoes that frequently have big eruptions, rather than those that mainly have small eruptions even though they might be capable of larger ones.

*So we made an equation:*

**One of the really difficult things in calculating the numbers for this category is that our ‘super volcanoes’ are potentially **so much more **devastating than some of our other volcanoes, that it is difficult to compare them on the same scale. Just like comparing mole hills with mountains. In order to get around this problem we just do some simple maths to end up with a score.*