Faults & Earthquakes

So, how are faults and earthquakes related?

Earthquake is a term used to describe both sudden movement of a fault, and the resulting ground shaking and radiated seismic energy that is caused by the slip volcanic activity or sudden stress changes in the earth.

When seismologists think of an earthquake, this image of a seismogram is what comes to their minds. There are 2 important measurements on a seismogram. The amplitude and the frequency.

The amplitude is the size of the wiggles on an earthquake recording.

The frequency is the number of times something happens in a certain period of time, such as the ground shaking up and down or back and forth during an earthquake.

A seismogram is a record written by a seismograph in response to ground motions produced by an earthquake, explosion, or other ground-motion sources.

The focus is the point within the earth where an earthquake rupture starts. The epicenter is the point directly above it at the surface of the Earth.

1. Magnitude is a measure of the amount of energy released during an earthquake. It may be expressed using several magnitude scales. One of these, Used in Southern California, is called the Richter scale.
2. (Information about magnitude can be found on the Magnitude & Energy page)