Elastic rebound theory

Elastic rebound

The mechanisms and processes involved when earthquakes occur are extremely complex. However some of the characteristics of earthquakes can be explained by using a simple elastic rebound theory.

Over time stresses in the Earth build up (often caused by the slow movements of tectonic plates). At some point the stresses become so great that the Earth breaks... an earthquake rupture occurs and relieves some of the stresses (but generally not all).

In earthquakes these ruptures generally happen along fault planes, or lines of weakness in the Earth's crust.

Types of fault

There are three basic types of fault, which are shown below. The outer crust of the Earth is divided into rigid plates that are called tectonic plates. The edges of these plates are known as plate boundaries.  Geologists and seismologists use these three fault types to describe the faulting at tectonic plate boundaries to help understand how the plates have moved relative to one another.

Normal fault

Types of fault animations

Classroom activities

What is an earthquake? Movement of faults and boundaries using foam blocks

Using pieces of foam or card you can model the movement of tectonic plates in different kinds of faults and boundaries.

Modelling an earthquakeModelling an earthquake

In these three tasks, you are going to use a brick being pulled along a surface covered in sandpaper to model the behaviour of an earthquake.

Related topics

Divergent boundary Plate tectonics

Tectonic plates can move relative to each in different ways. This movement gives rise to different types of plate boundaries with different properties and characteristic earthquakes.

Core structure The structure of the Earth

Studying the signals from distant earthquakes has allowed scientists to determine the internal structure of the earth.