This deep dive covers P-Waves and S-Waves within Seismic Waves for GCSE Physics. Revise Seismic Waves in Waves for GCSE Physics with 13 exam-style questions and 15 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 2 of 14 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
🌍 P-Waves and S-Waves
Earthquakes produce two main types of seismic waves that travel through the Earth:
P-waves (Primary waves)
P-waves are longitudinal waves — particles vibrate back and forth in the same direction as the wave travels, creating compressions and rarefactions. They can travel through solids AND liquids and are the fastest seismic waves, arriving at seismograph stations first (hence "Primary").
S-waves (Secondary waves)
S-waves are transverse waves — particles vibrate at right angles to the direction of wave travel. They can only travel through solids — they cannot pass through liquids because liquids cannot support shear (sideways) forces. S-waves arrive after P-waves (hence "Secondary") and do not reach the far side of Earth from an earthquake.
Practice questions for Seismic Waves
What type of wave is a P-wave (primary seismic wave)?
State two differences between P-waves and S-waves in terms of how the particles move and what materials they can travel through.