Answers to Exploration Questions: Volcanoes
ANSWER: This picture shows a volcano forming at a subduction zone. When an oceanic plate collides with a continental plate, it sinks into the mantle below. As the oceanic plate sinks, fluid (shown in purple) is squeezed out of it. The fluid flows up into the mantle rock above and changes its chemistry, causing it to melt. This forms magma (molten rock – shown in orange). The magma rises and collects in chambers within the crust. As magma fills the chamber, pressure grows. If the pressure gets high enough, the magma can break through the crust and spew out in a volcanic eruption.