Topic 4: Waves and the Earth


4.4 Recall that sound with frequencies less than 20 hertz, Hz is known as infrasound
4.5 Describe uses of infrasound, including:
  • communication between animals
  • detection of animal movement in remote locations
  • the detection of volcanic eruptions and meteors
1.15 Use this equation for all waves: Wave speed (metre/second, m/s) = distance (metre, m)/ time (second, s)


4.1 Recall that sound with frequencies greater than 20 000 hertz, Hz is known as ultrasound
4.2 Describe uses of ultrasound, including:
  • sonar
  • communication between animals
  • foetal scanning
4.3 Calculate depth or distance from time and velocity of ultrasound
1.15 Use this equation for all waves: Wave speed (metre/second, m/s) = distance (metre, m) x time (second, s)

Seismic waves

4.6 Recall that seismic waves are generated by earthquakes or explosions

4.9 Recall that seismic waves can be longitudinal (P) waves and transverse (S) waves and that they can be reflected and refracted at boundaries between the crust, mantle and core
H 4.11 Demonstrate an understanding of how P and S waves travel inside the Earth including reflection and refraction

Earthquakes practical

4.7 Investigate the unpredictability of earthquakes, through sliding blocks and weights

Detecting earthquakes

4.8 Explain why scientists find it difficult to predict earthquakes and tsunami waves even with available data
4.10 Explain how data from seismometers can be used to identify the location of an earthquake
4.12 Explain that the Earth’s outermost layer is composed of (tectonic) plates in relative motion due to convection currents in the mantle
4.13 Demonstrate an understanding of how, at plate boundaries, plates may slide past each other sometimes causing earthquakes