Does an earthquake produce different types of wave?
An earthquake produces three kinds of waves P waves, S waves, and surface waves. The first waves to arrive are the P waves, sometimes called sound or compression waves, which are often heard rather than felt. They travel at 4 8 km/sec (14,000 28,000 km/h) in the earth s crust. They will often hit a house with a bang or a boom. P waves do not generally cause a lot of damage except in the biggest earthquakes. Next to arrive are the S waves, travelling at 2.5 4 km/sec (9000 14,000 km/h). The S waves pack the bigger punch because they are bigger and move at right angles to the direction of travel. This side-to-side motion (like a snake wriggling) is what causes the most damage to structures. S waves cannot travel through liquids because liquids have no shear strength and therefore don t support the mode of travel of S waves. Seismologists use the difference in arrival time between P and S waves to calculate the distance between the earthquake source and the recording instrument. Even with
