How s waves and p waves used to determine how far away epicenter?

S-waves (secondary waves) and P-waves (primary waves) are used to determine the distance to an earthquake's epicenter by analyzing their arrival times at seismic stations. P-waves travel faster than S-waves, so the difference in arrival times between the two waves can be measured. By calculating this time difference and knowing the speed of both types of waves, seismologists can determine how far the waves have traveled, which helps pinpoint the epicenter's distance. This information is then used in conjunction with data from multiple seismic stations to triangulate the exact location of the epicenter.