Volcanoes and Earthquakes.

1. Volcanoes and Earthquakes.

2. The Earths crust • The earths crust is in constant motion. • Volcanoes and earthquakes arise as sections of crust push toghether or pulled apart. Volcanoes and earthquakes are more common in certain parts of the world. By monitoring ground vibrations scientists can sometimes • Predict a massive earthquake or volcanic eruptions and warn people.

3. The solid surface • The solid surface layer of the Earth is known as the crust and ranges 5km to 80 km in thickness. Beneath the crust is the mantle which is 2,900km thick and made up of molten rock. The core is the centre of the Earth and is mostly made of iron. It has a liquid outer core and a solid inner core and is around 4,500C .

4. Volcanoes • Volcanoes form when molten rock is pushed up trough the crust. • When subduction the occurs, the oceanic plate melts underground, creating a supply of molten rock. The rock is then released as lava in a volcanic eruption.

5. Earthquakes • The earths crust is broken up into a number of separate plates. Earthquakes are caused when two plates collide. The strongest earthquakes occur along breaks in the earths crust called fault lines.

6. Friction • Earthquakes are the result of frictional forces as two plates move side by side. The plates judder as they slide past each other and each judder causes an earthquake.