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Seismic waves
Short answer
P-waves are compressional, fastest, travel through all media; S-waves are shear, slower, travel only through solids. Surface waves: Love waves (horizontal shear) and Rayleigh waves (elliptical rolling, most destructive). S-P arrival time difference gives epicentral distance.
Describe the different types of seismic waves generated during an earthquake (differentiate P-wave and S-wave).
Seismic waves are the elastic waves produced by an earthquake that carry energy through and over the earth. They are of two main groups.
A. Body waves (travel through the interior)
- P-waves (primary, compressional): particles vibrate parallel to the direction of travel (push-pull); fastest (about 5-8 km/s in crust); travel through solids, liquids and gases; arrive first.
- S-waves (secondary, shear): particles move at right angles to the direction of travel; slower (about 3-4.5 km/s); travel through solids only, not liquids (so they showed the outer core is liquid); arrive second; more damaging than P-waves.
B. Surface waves (travel along the surface)
- Love waves (L): horizontal shear motion, no vertical movement; fast surface wave.
- Rayleigh waves (R): elliptical rolling motion like ocean waves; slowest, but largest amplitude and most destructive.
Difference between P- and S-waves
| Point | P-wave | S-wave |
|---|---|---|
| Motion | Compression and dilation (longitudinal) | Shearing (transverse) |
| Speed | Faster | Slower (about 0.6 of P) |
| Medium | Solid, liquid, gas | Solid only |
| Arrival | First | Second |
| Damage | Less | More |
The S-P time lag at a station gives distance to the epicentre, and three stations locate it by triangulation.
✓ Answer checked by Claude Opus 5.5 (high effort)
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