We have produced the numbers and indexes used in Top Trumps from the real data associated with their activity.
Two categories: the Volcanic Explosivity Index and height will be familiar concepts but others less so.
Here we describe some of the teaching concepts behind our choice of categories. You might find this helpful to have at hand if you have a class engaged in playing one of the games. To have the absolute numbers used in each of the indexes you will need to buy a pack of the cards!
Elsewhere on this website we provide you with background information about each of the ‘Top Trumps” Volcanoes. This will also be helpful.
Volcanic Explosivity Index. From 0 to 8. This is the largest eruption recorded from that volcano. Not all volcanic eruptions from the same volcano are the same size! However, some volcanic systems and types will have tendency to produce larger eruptions. There is a representative range in VEI for the 30 chosen volcanoes. You can use them to discuss the range of size. Don’t forget there is an order of magnitude variation between each number on the index. So a VEI 8 eruption is roughly 1,000 times the size of the VEI 5 eruption!
Height (m) From 0 to 5897 m (Cotopaxi in Ecuador) Pretty impressive in this category are the two intra-plate island volcanoes: Kilauea and Teide. They have built up huge edifices from far below sea-level to heights of 1,247 and 3,718 m respectively. Their edifices are entirely volcanic in origin but they are not the tallest. Usually the very tallest volcanoes are large ‘stratovolcanoes’ that have been built onto thick, well developed parts of continental lithosphere where their high elevations are also the product of regional mountain-building processes too.
Deadliness. An Index from 0 to 1000 (Krakatau in Indonesia) Essentially a measure of fatalities in the past. We have quite deliberately NOT used direct casualties in this figure. However, we created the index from the total number of historical fatalities directly attributed to volcanic activity. For some volcanoes this involves more than one fatal eruption (for example, Merapi in Indonesia, Mayon in the Phillipines). This explains why Yellowstone does not score well in this category. It has not had any historical fatalities. The 1883 eruption of Krakatau caused over 35,000 deaths. Although the 1815 eruption of Tambora killed many more people, a large majority of these were from secondary starvation from the devastated agricultural production in the region.
Wow! Factor An Index from 0 to 100 (Fuji in Japan) ! Our most subjective factor. This was an interesting category to construct. There are so many things about volcanoes, that make you go wow! The pictures on the cards reflect the large differences. Some volcanoes have beautiful and impressive edifices that are very imposing or grand (Fuji, Villarica, Mayon), some frequently erupt fantastic globules of red-spattering magma (e.g. Yasur), some leave behind traces of huge scale eruptions (e.g. Vesuvius). The range of these types is represented in our volcanoes. You can discuss with you class what aspects of volcanic activity makes them go Wow!
Unpredictability An index from 0 to 100 that relates to the relative variability of activity at that volcano. We used this category to find a way to express the ‘range’ of activity that a volcano has, in numbers. It is essentially an expression the range of sizes of activity and its frequency of eruption. A volcano that erupts relatively often but with little change in the style or size of activity is more predictable than one capable of producing a wide range of eruptions. An example of a low scoring ( relatively predictable) volcano is Stromboli. In the STREVA Project we are working to improve the way in which monitoring data can provide additional warnings of that activity. There is a blog here about one piece of research that looked at how satellites might improve the way we can detect early signs of activity.
Devastation Potential. An index from 0 to 1000 that provides a measure of future possible havoc from one of the largest eruptions that volcano is likely to produce. This is the category where those volcanoes that produce the VEI 7 or 8 eruptions will score more highly. We also factored in the amount of people living in relatively close proximity to these volcanoes, so the highest scoring in this category is Campei Flegrei, which has the potential to produce an enormous eruption and is in the heart of an urbanised area. Still no maximum points for Yellowstone! This is a very useful vehicle to provoke a discussion about volcanoes that are close to population centres, and to discusse the potential global impacts of the very largest eruptions. One of the key objectives of the STREVA Project is to increase the resilience to future eruptions from volcanoes. You can read about that work here.