Tectonic Hazards Flashcards
Structure of the Earth
Out going in
Oceanic Crust
Continental Crust
Mantle
Outer Core
Inner core
Features of Inner Core
1,200 km thick
6,000+ Celsius
Made of solid Iron
Features of Outer Core
2,250 km thick
2,700+ Celsius
Liquid
Features of Mantle
2,900 km thick
3,000 Celsius
Viscous, softened rock & plastic
Features of Continental Crust
40-60 km thick
Very dense
Solid Granite
Features of Oceanic Crust
3-5 km thick
Least dense
Solid Basalt
Convection Currents
1) Rising convection current bring hotter less dense magma to surface
2) Magma is ejected & solidifies to form the new crust - plates diverge
3) Convection currents spread sideways carrying the plates with it
4) Magma descends back to the mantle to be reheated
Constructive Plate Boundary
1) Core heats up magma
2) Hot magma rises and solidifies to form new rock
3) Magma fills the gap
4) The crust gest pushed apart through Ridge Push
Example of a constructive plate boundary
South American & African Plate
Destructive Plate Boundary
- Convergent
- Subductive
1) Oceanic Plate gets pushed towards the continental plate
2) Less dense curst (oceanic) gets pushed under = subduction also known as slab pull
3) Crust starts to met due to pressure and heat in mantle
4) Pressure builds
5) Magma gets pushed up and volcano on land erupts
Destructive Plate Boundary
- Convergent
- Collision boundary
1) Two continental crusts push towards each other
2) Neither plate subducts so pressure builds up
3) Plates push upwards forming fold mountains under great pressure
4) The fold mountains will continue to grow due to continuous continental movement
Example of a Destructive Collision boundary
Himalayas
Conservative Plate Boundary
- Transform
1) Plates slide past each other - either same or opposite direction
2) No land is destroyed or created therefore no volcanic activity
3) There are many earthquakes as plates stick together and can cause friction
Example of a Conservative Transform Boundary
San Andreas Fault
How are Volcanoes formed
Rock is melted in a subduction zone, constructive boundary or hot spots.
The less dense magma rises and may flow onto the surface.
Gas and bubbles in the magma creates a higher pressure forcing the magma out of the volcano causing and eruption.