Question: Why do earthquakes occur?

James Hickey answered on 14 Nov 2013:

Hi alfiebcfc!

Most earthquakes occur at the edges of things we call plate tectonics.

Plate tectonics are pieces of the Earth’s surface that fit together like a jigsaw puzzle. You can see an image of it here: http://geology.com/plate-tectonics.shtml

Each plate moves separately to the others, and often in different directions. Where the plates rub and slide against each other lots of force is generated and pressure can build up. When the pressure and stress gets too much, the rocks at the edge of the plate slip and break and this is what causes an earthquake. The energy that is released from this break travels through the earth in waves which we can feel as the ground shaking.

Imagine this: if you hold a ruler you can bend it slightly when you press on both ends. But if you press too hard the ruler snaps, releasing the stress you were putting on it. The Earth’s crust acts in a similar way…