Video · + 1 min read
What happens when a continental and ocean plate collide?
When a continental and ocean plate collide, a large, explosive stratovolcano can form. The video is showing the eruption of Mt. St. Helens on May 18, 1980. Mt St. Helens is one of many volcanoes in the Cascade Volcanic Arc.
Let's take a closer look at what happens at a continental to oceanic plate collision!
The oceanic crust is thin and dense. The continental crust is much thicker and less dense. When the two collide, the oceanic crust is moves under the less dense continental crust. This is called subduction.
As the oceanic crust subducts below the continental crust, what happens next?
As the oceanic crust goes beneath the less dense continental crust, it is under a great deal of pressure. and it continues to be pulled deeper into the mantle (slab pull). With the higher temperature, pressure, and additional water content melt occurs. Also, friction occurs as the "cold" rock is subducted and earthquakes can form.
How Do Volcanoes Form?
Volcano Formation (http://volcano.oregonstate.edu/how-earths-plates-move-lesson-3)
The magma (melted rock in the mantle and crust) begins to rise because it is less dense than the surrounding rock. A magma pool is created just below the continental crust. When there is enough pressure build up, the magma can reach the surface and a volcano can form.