Earthquakes produce several types of shock waves. the most well-known are the p-waves (p for primary or pressure) and the s-waves (s for secondary or shear). in the earth's crust, the p-waves travel at around 6.5 km/s while the s-waves move at about 3.5 km/s. the actual speeds vary depending on the type of material they are going through. the time delay between the arrival of these two waves at a seismic recording center tells geologists how far away the earthquake occurred. if the time delay is 73 s, how far from the seismic station did the earthquake occur?