1. Volcanoes 1 2
Volcanoes will form where the Earth’s structure allows a path for magma from the asthenosphere to rise.
Subduction zones
Hot spots 1 2

2. Hot Spots 1. Magma (melted mantle) builds under the lithosphere.
2. The pressure will increase as more mantle is made.
3. Eventually the magma will pierce the lithosphere and make a large volcano.

3. Volcanoes 1 2
Volcanoes will form where the Earth’s structure allows a path for magma from the asthenosphere to rise.
Subduction zones
Hot spots 1 2

4. Volcanoes 2 1
1. Subducting plate melts to make magma. Increased pressure in asthenosphere.
2. Some magma is forced up through the lithosphere to make a volcano.

5. Earthquake Mechanism Earthquakes will occur along all boundaries.
Earthquakes are felt as vibrations in the Earth.
The tectonic plates are always moving but the movement is not always smooth.
Sources of friction include
one plate moving over another
two parallel plates rubbing together
Tectonic forces will eventually
overcome these forces
The plate “springs” back into position

6. Distribution of Earthquakes

7. Earthquake Locations Focus Epicentre
– This location is the source of the earthquake 1
Epicentre
– Found on the surface directly above the focus 2 2 1

8. Seismic Waves
We can learn about the structure of the Earth by watching the way that seismic waves travel under the surface.