A big challenge for volcanologists is being able to predict when a volcano is going to erupt, what it is going to do when it erupts, and how long it will be before it stops again. All of these factors contribute to a volcano’s unpredictability.
No two volcanoes are completely alike. They can vary in the size and style of their eruptions. Some eruptions can go on for days, months or even years. Some can be over in a matter of minutes. Even at the same volcano, no two eruptions are completely alike. You can find a useful description of the different kinds of eruption at volcano world. None the less, some volcanoes (like Yasur) erupt in pretty much the same way each time, and some can have a much bigger variation between eruptions (like Vesuvius). In our unpredictability category, we wanted to explore this.
We use the Smithsonian Institution Global Volcanism Program Eruptive Record of a volcano to calculate the average size (VEI) of eruptions, and multiplied it by the range of that number. We also factored in the number of eruptions that it has had. This way, a volcano that has had a lot of eruptions all of the same size will have a low unpredictability, while a volcano that is less well known and may have had both large and small eruptions will have a high unpredictability. Can you guess what our most unpredictable volcano is…??