Here's why:
* Density: Oceanic crust, being denser than continental crust, will subduct when it collides with another oceanic plate.
* Older vs. Younger: The older oceanic plate is generally denser than the younger one due to cooling and the accumulation of sediment. This denser plate will be forced beneath the younger, less dense plate.
Consequences of Oceanic-Oceanic Subduction:
* Volcanic Island Arcs: The subducting plate melts as it descends, creating magma that rises to the surface and forms a chain of volcanic islands called an island arc. Examples include the Mariana Islands and the Aleutian Islands.
* Trench Formation: The point where the two plates meet forms a deep trench, which is the deepest part of the ocean.
* Earthquakes: As the plates grind past each other, they generate powerful earthquakes.
Let me know if you have any more questions about subduction!
