Earthquake

Key Stage 2

Meaning

An earthquake is when the ground shakes.

Key Stage 3

Meaning

An earthquake is when the ground shakes.

About Earthquakes

Earthquakes are usually caused by tectonic plates rubbing against each other.

Key Stage 4

Meaning

An Earthquake is when the ground undergoes a violent shaking motion as a result of plate movement. This often results in damage to the local environment and severe loss of life.

About Earthquakes

Earthquakes occur along all three types of Tectonic Plate Margin when tension builds up as the plates move.

Destructive Plate Margins typically occur between a continental plate and oceanic plate. Upon collision, the denser oceanic plate is forced under the lighter continental plate in a process known as subduction. There is a huge build-up of friction between the two plates as this happens, until the force becomes so great the plates no longer move. As the plates are released and jerk away from each other they release shock waves that that spread from the focus deep in the mantle where the plates are coming together. The shock waves are then felt on the surface of the crust and they are most strongly felt at the Epicentre which is the point directly above the focus. This is an earthquake.

At Conservative Plate Margins the plates grind past each other causing a build-up of friction. As tension builds the plates eventually become stuck. As the plates are released and jerk away from each other they release shock waves that that spread from the focus deep in the mantle. The shock waves are then felt on the surface of the crust in the form of an earthquake. The shock waves are most strongly felt at the Epicentre which is the point directly above the focus.

At Constructive Plate Margins the plates are moving away from each other and this causes cracks in the plates as they move. Tension then builds in these cracks and is eventually released in the form of shock waves that can be felt of the surface of the earth at the crust as an earthquake.

Earthquakes come in a variety of strengths therefore there is a scale that shows you how strong each earthquake is and how much damage it is likely to do. This is called the moment magnitude scale. This scale measures the amount of energy released by an earthquake and is measured logarithmically. This means that a magnitude 2 earthquake is ten times stronger than a magnitude 1 earthquake. Earthquakes below magnitude 6 only cause slight damage to buildings and earthquakes magnitude 7 and above can cause high levels of damage and large loss of life.