The ground beneath our feet seems rock-solid, but our planet's surface is in fact a dynamic grid of slowly-moving sections, known as tectonic plates. This motion is usually incredibly slow, showing itself only on geological time scales. (North America and Europe, for example, are drifting apart at the rate of just five centimetres per year.) This motion causes stress to build up in the crust. If the stress rises beyond a critical level, a portion of the crust will give way, shifting suddenly and violently. The result is felt as an earthquake.
So, let us now find out more about earthquakes and our moving earth.
|WHAT is an earthquake|
|WHY do earthquakes form|
|HOW do earthquakes form|
|WHERE do earthquakes form|
|WHAT types of earthquakes are there|
|HOW are earthquakes measured|
|WHAT are the safety measures|