All the scientific people say that Yellowstone will erupt again, but no one knows when. Everything is still a guessing game. They say that it could be a super volcano. This is a volcano capable of producing a volcanic eruption with an ejected volume greater than 1,000 km (240 cu mi). This is thousands of times larger than normal volcanic eruptions. Super volcanoes can occur when magma in the mantle rises into the crust from a hotspot but is unable to break through the crust, and pressure builds in a large and growing magma pool until the crust is unable to contain the pressure. Such is the case for the Yellowstone Caldera. They can monitor and watch, but it is still a guessing game. I based my book on one type of eruption that may take place, which is a Plinian eruption. These eruptions are marked by their similarity to the eruption of Mount Vesuvious in AD 79. Plinian eruptions are marked by columns of gas and volcanic ash extending high into the stratosphere, a high layer of the atmosphere. The key characteristics are ejection of large amounts of pumice and very powerful continuous gas blast eruptions.
