Virtual Earthquake Labs

Virtual Earthquake will show you the recordings of an earthquake's seismic waves detected by instruments far away from the earthquake. The instrument recording the seismic waves is called a seismograph and the recording is a seismogram. The point of origin of an earthquake is called its focus and the point on the earth's surface directly above the focus is the epicenter. You are to locate the epicenter of an earthquake by making simple measurements on three seismograms. Additionally, you will be required to determine the Richter Magnitude of that earthquake from the same recordings. Richter Magnitude is an estimate of the amount of energy released during an earthquake.

What are Earthquake (Seismic) Waves?

A seismic wave is simply a means of transferring energy from one spot to another within the earth. Although seismologists recognize different types of waves, we are interested in only three types:

• P (primary) waves, which are similar to sound waves,
• S (secondary) waves, which are a kind of shear wave, and
• L (longitudinal) waves, surface waves.