How is an Earthquake’s Epicenter Located?

General purpose of this lecture is to present on how is an Earthquake’s Epicenter Located. There are hundreds of seismic data recording stations throughout the United States and the rest of the world. In order to locate the epicenter of an earthquake, you need to estimate the time interval between the arrival of the P and S waves (the S-P interval) on the seismograms from at least three different stations. Three seismograph stations are needed to locate the epicenter of an earthquake. A circle where the radius equals the distance to the epicenter is drawn. The intersection of the circles locates the epicenter.