# Explain why S-waves cannot be detected at seismometer stations on the opposite side of the Earth from an earthquake.

> WJEC GCSE Physics (Wales) — 1.7 Seismic waves · Explain · 4 marks

> During a large earthquake, seismometer stations positioned more than about 105° away from the earthquake epicentre detect P-waves but record no S-waves.

## Mark scheme (4 marks)

1. S-waves are transverse waves that can only travel through solids
2. The outer core of the Earth is liquid
3. S-waves are blocked / absorbed / stopped when they reach the liquid outer core
4. This creates an S-wave shadow zone on the far side of the Earth

## Key terms

- [S-waves](https://www.gradenine.co.uk/glossary/s-waves)

## Related

- [Revision notes for WJEC GCSE Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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