Earthquakes produce seismic waves that can travel long distances through Earth. Two types of seismic waves are p-waves and s-waves. P-waves typically travel 6−13 km/sec and s-waves typically travel 3.5−7.5 km/sec. Figure 1 shows how p-waves and s waves move and are
refracted (bent) as they travel through different layers of Earth’s interior. Figure 2 shows a seismograph (an instrument that detects seismic waves) recording of p-waves and s-waves from an earthquake. Figure 3 shows, in general, how long it takes p-waves and s-waves to travel given distances along the surface from an earthquake focus (point of origin of seismic waves).