Question

Think-Pair-Share: Based on the video, what do you think a convergent (destructive) boundary is? How do the plates interact with each other?

Answer 1

A convergent (destructive) plate boundary is where two tectonic plates move toward each other and one plate is forced down into the mantle (is "destroyed" or recycled). Key points about how the plates interact:

- Subduction: When an oceanic plate meets a continental plate, the denser oceanic plate sinks beneath the lighter continental plate into the mantle along a subduction zone. This destroys old oceanic lithosphere.
- Melting and volcanism: The subducted plate releases water and lowers the melting temperature of the overlying mantle, producing magma that rises to form volcanic arcs (continental volcanic arcs like the Andes, or island arcs like Japan).
- Oceanic–oceanic collisions: The older/denser oceanic plate subducts under the younger/less dense oceanic plate, forming an island-arc chain and a deep ocean trench (e.g., the Mariana Islands/Trench).
- Continental–continental collisions: When two continental plates collide, neither easily subducts. Instead the crust crumples and thickens, producing high mountain ranges (e.g., India colliding with Eurasia → Himalayas).
- Hazards and features: Convergent boundaries produce deep ocean trenches, volcanic arcs, intense earthquakes (including deep-focus quakes along the subducting slab, a Benioff zone), and mountain building. They are called “destructive” because lithosphere is consumed and recycled into the mantle.