Earthquakes                         Quiz

• An earthquake is a movement in the Earth's crust. The crust is made up of a number of plates which float on the material beneath. While the continents feel like 'solid ground' they are in fact rafts that are floating. Where these plates move into, past or away from each other, the crust is very unstable. As the plates move into different positions, they cause tremors or earthquakes.

• An earthquake produces a number of waves in the earth's crust. There are three types, P, S and L waves

• P (Primary) waves are compression waves. They travel fastest and can travel through both liquids and solids.

• S (Secondary) waves are transverse waves. They travel slower than the P waves. Observation stations can use the difference between the arrival of the P and S waves to work out how far away the epicentre of the earthquake was from the observation station.

• L ( Love waves named after AE Love who predicted them) waves are the slowest waves. They are surface waves, which travel along the surface of the crust as a ripple. They are the waves that cause most of the damage in an earthquake. The damaging effect of these waves dies out quite rapidly as the waves move out from the centre of the quake.

It is very difficult to monitor and predict earthquakes. This is so because we are trying to monitor the movement of the ground we stand on. However, we move with the ground as it shakes. So, we need equipment that can measure the movement of the earth without moving with it. In most seismographs, this is achieved by attaching the seismograph securely to the ground. Inside the seismograph is a heavy object that is suspended so that it will barely move when the rest of the seismograph moves. When an earthquake strikes, the seismograph will move with the ground, but the heavy object inside will remain stationary. As the seismograph shakes with the ground, the object then uses a marker of some sort to record the motion of the seismograph relative to the heavy object.



Another difficulty in monitoring earthquakes is the fact that they happen deep underground, usually impossible to reach with measuring equipment.

Although we do know that certain areas are likely to experience earthquakes, predicting exactly where and when they will occur is almost impossible. As a result we cannot get measuring equipment into the right place. Furthermore, the earthquake may be so severe that it will actually destroy the equipment set up to measure it.

In order to predict where an earthquake will strike next, people monitor all the parts of the Earth that are on Plate Margins. University geology departments and government geology departments all around the world do this with equipment such as seismograms.


A lot of study has gone into predicting where earthquakes will strike and our methods and technology are improving. Having this sort of knowledge is important, as it will help save lives and minimise damage to property.

The Richter Scale


Earthquakes are measured by the richter scale /10.  The Newcastle Earthquake in 1989 measured 5.6 and 18 people were killed. The San Fransisco earthquake of 1906 measured 7.8 and killed over 3000.