Waves for detection and exploration

• Ultrasound waves have a frequency higher than the upper limit of hearing for humans
• Ultrasound waves are partially reflected when they meet a boundary between two different media
• The time taken for ultrasound reflections to reach a detector can be used to determine how far away such a boundary is
• Ultrasound waves can be used for both medical and industrial imaging
• Seismic waves are produced by earthquakes
• P-waves are longitudinal seismic waves
• P-waves travel at different speeds through solids and liquids
• S-waves are transverse seismic waves
• S-waves cannot travel through a liquid
• P-waves and S-waves provide evidence for the structure and size of the Earth’s core
• P-waves are faster than S-waves
• Echo sounding, using high frequency sound waves is used to detect objects in deep water and measure water depth