"There are a lot of really smart people out there. Some of them visit this website. Whatever you're smart at, maybe it's something you do as a hobby, maybe it's something you learned in your major today, maybe it's something your dad taught you how to do: share it with me. Don't get too controversial, I don't want a debate thread. Just a place to share some knowledge that you have. I'll start. A caldera is the vulcanologist's term for what is commonly referred to as a supervolcano. A caldera is formed by a massive chamber under the crust. If the magma is high in silica, it will be viscous and the magma flow will be impeded and incredible pressures will build. When the pressure is released, usually through a volcanic eruption, the magma chamber empties and without the pressure to support it, collapses. The areas affected can cover thousands of square miles. Boom. "