Tectonic Hazards
Plate Tectonic Theory
Structure of the Earth
Crust
The crust is the layer we live on. It is usually between 10km and 60km thick. The crust is actually quite thin relative to the size of the earth
Mantle
The mantle is the thickest part of the earth. it is about 2900km thick. the mantle is sometimes described as semi molten. But actually it is hard rock on top and as you go towards the outer core it begins to melt into magma.
Core
Inner core
Outer core
The outer core is the outer part of the core and it is mainly liquid. The outer core is also mainly made out of nickel and iron. The temperature of the outer core is around 5500 degrees.
The inner core is mainly a solid ball because of the great pressure on it. the inner core is around 5500 degrees as well. the inner core is mainly made out of iron.
Why do plates move?
Ridge push
As magma rises the plates are pulled apart. Then as the magma rises it cools. When the magma cools it forms new plate material which becomes more dense. This will slide down and pull the plates even further apart.
Slab pull
When two plates meet they will collide. When they collide the denser plate will sink back into the mantle due to gravity. This will pull the rest of the plate along with it therefore leading the plate downwards.
Convection currents
The hot core causes magma to rise in the mantle and sink towards the core when it cools. This is called convection. Convection builds pressure and carries plate with it.
Constructive Plate Margins
On constructive plate margins the plates move away from each other. This means that magma is able to rise up out of the earths mantle this will cool as it rises and will create new plate material.
Constructive plate margins create volcanoes and cause earthquakes.
Destructive Plate Margins
On destructive plate margins the plates are moving towards each other and so the denser plate will sink into the magma and melt. This is called subduction
Destructive plate margins cause earthquakes and volcanoes as gas and magma is released from the mantle
Conservative plate margins
At conservative plate margins two plates slide past each other. But these can get stuck and create pressure.
Due to the pressure sometimes caused at conservative plate margins earthquakes can occur when the pressure it released.
Landforms include oceanic ridges/trenches and volcanoes.