We've all heard of volcanoes - but what's a supervolcano? Time for a Geek Out! Richard starts out with a discussion on the core concepts behind our understanding of volcanoes and vulcanism - and how before modern times, there have been occasional massive volcanic eruptions so large they are classed as super-eruptions. The best-known supervolcano today is the Yellowstone Caldera, and depending who you ask, it's due for an eruption. What would a super-eruption look like, and what can we do about it?