Divergent
What is the main motion of plates at a divergent boundary?
Plates move away from each other
What happens to plates at a convergent boundary?
Plates move toward each other
What two types of plates collide at a collision boundary?
Two continental plates
How do plates move at a transform boundary?
They slide past each other
What type of crust is usually formed at divergent boundaries?
New oceanic crust
Which plate subducts: oceanic or continental?
Oceanic plate
Why does subduction not occur at collision boundaries?
Plates are too buoyant to sink and they have similar densities
Is crust created or destroyed at transform boundaries?
Neither
What landform is commonly created at a divergent boundary on the ocean floor?
Mid-ocean ridge
What deep ocean feature forms at a subduction zone?
Trench
What major landform forms at collision boundaries?
Mountain ranges
What geologic hazard is most common at transform boundaries?
Earthquakes
Why does magma rise at divergent boundaries?
Because the crust opens, allowing magma to flow
Why do volcanoes form above subduction zones?
Water lowers the melting point of mantle rock, producing magma. (Or friction from the plates melt the rock, producing magma)
Why don’t volcanoes usually form at collision boundaries?
No subducting slab, so no mantle melting
Why are there no volcanoes at transform boundaries?
No subduction or magma generation
Why are earthquakes at divergent boundaries usually shallow?
Because plates pull apart near the surface, with little depth involvement
Why do subduction zones produce earthquakes at many different depths?
The sinking slab causes stress from shallow to deep levels
What happens to the crust during a continental collision?
It thickens, folds, and uplifts
Why can transform earthquakes be very damaging even though they are shallow?
Shallow focus releases energy directly at the surface