How can you determine the epicenter of an earthquake?
The arrival times of P and S waves are used to determine the distance to an earthquake using standard travel-time curves. P & S waves each shake the ground in different ways as they travel through the Earth. P waves are faster than S waves so by looking at seismograms, scientists can accurately locate the epicenter as well as the hypocenter, or focus of the earthquake at depth. (Recorded during a 2007 teacher workshop on earthquakes and tectonics. Speaker is Dr. Robert Butler, University of Portland Oregon)
- There is a predictable distance between the arrival of a P wave and the slower S wave
- Using the arrival times of the P and S waves from 3 different stations distances to epicenter can be determined.
- The intersection of the 3 cirles gives epicenter location.