tectonics Flashcards
How is seafloor spreading formed?
- happens at divergent plate boundaries
- magma rises from the mid-ocean ridge
- new oceanic crust is formed
What happens at divergent oceanic-oceanic plate boundaries?
Decrease in overlying pressure causes parts of the underlying mantle to melt, forming magma, which rises through the weak areas in the crust to the Earth’s surface, filling the gaps caused by the spreading plates. Lava then cools to form basaltic rocks, making up new oceanic crust, forming the mid-ocean ridge.
What happens at divergent continental-continental plate boundaries?
Rocks fracture to form parallel faults, which then collapses to form a rift valley. Decrease in overlying pressure causes parts of the underlying mantle to melt, forming magma. Magma rises through weak areas of the Earth’s surface, forming volcanoes. Earthquakes occur as stress and tension is released.
What happens at convergent oceanic-oceanic plate boundaries?
Denser plate subducts, forming the oceanic trench. High pressure forces water out of the oceanic crust, lowering the melting point of the overlying mantle, causing it to melt, forming magma. The magma then rises through weak areas of the Earth’s surface, forming a volcanic island.
What happens at convergent continental-continental plate boundaries?
Enormous pressure causes the rocks to be uplifted and buckled to form fold mountains, while friction along the convergent plate boundary causes earthquakes.
What happens at convergent oceanic-continental plate boundaries?
The denser oceanic plate subducts beneath the continental plate (OCEANIC IS ALWAYS DENSER), forming an oceanic trench. High pressure forces water out of its oceanic crust, lowering the melting point of the overlying mantle, forming magma. The magma rises through the weaker areas of the Earth’s surface forming volcanoes. Friction along the subducting oceanic plate causes earthquakes to occur. Enormous pressure at the plate boundary causes rocks on the continental plate to be uplifted and buckled, forming fold mountains.
What happens at transform plate boundaries?
Stress by the plate movement produces a fault. Earthquakes occur as one plate suddenly slides past the other.
How do tectonic processes result in earthquakes?
Rocks on either side of the fault get locked due to friction, causes stress to build up. When the stress exceeds the strength of the fault, the rocks snap, releases seismic waves, resulting in the ground shaking.
How do divergent plate boundaries result in volcanic eruptions?
Magma contains dissolved gases, making it less dense than the surrounding materials. (then the rest just say like how you would explain divergenr plae voundariws)
How do convergent plate boundaries result in volcanic eruptions?
Magma contains dissolved gases, making it less dense than the surrounding materials. (then the rest just say like how you would explain coemvergent plae voundariws)
What is magnitude of volcanic eruption determined by?
Amount of dissolved gases and magma viscosity. (more viscous = moves faster or smth)
What volcanoes are high and low silica magma associated with?
Stratovolcanoes and shield volcanoes
Where are earthquakes distributed?
Along all plate boundaries, with the largest concentration at the pacific ring of fire
Where are volcanoes distributed?
Along divergent and convergent plate boundaries.
Where are tectonic hazards distributed?
Near all plate boundaries, earthquakes, and volcanoes. Tsunamis and ash may spread beyond geographic region
