P1.20 Seismic waves

P1.20 Seismic waves

1. Seismic waves can be caused by earthquakes or explosions.

   • And are detected by seismometers

2. There are two types of seismic waves P waves and S waves.

   • P waves are longitudinal and push and pull
   • S waves are transverse and they go side to side.

3. Investigating the earth

   • Seismic waves help scientists to find out the different materials in the earths core, mantle and crust.
   • The speed of seismic waves changes gradualy as the rocks have different properties
   • Parts of the waves are reflected at the different boundaries.