section_path: Measurement and location/Seismic waves/Speed of seismic waves
section_name: Speed of seismic waves
paragraph_text: Speed of seismic waves
  
  Propagation velocity of the seismic waves through solid rock ranges from approx. 3 km/s (1.9 mi/s) up to 13 km/s (8.1 mi/s), depending on the density and elasticity of the medium. In the Earth's interior, the shock- or P-waves travel much faster than the S-waves (approx. relation 1.7:1). The differences in travel time from the epicenter to the observatory are a measure of the distance and can be used to image both sources of earthquakes and structures within the Earth. Also, the depth of the hypocenter can be computed roughly.
  
  P-wave speed
  
  S-waves speed