Waves

• wavelength: distance over which the wave repeats

• amplitude: distance from undisturbed position to point of max displacement (crest or trough)

• frequency: number of waves that pass a given point in a certain amount of time

  • higher frequency waves attenuate more quickly than lower frequency waves

Seismic Waves

• in an earthquake, energy is released when movement begins at the hypocenter

• the energy moves outwards as seismic waves through the earth

  • like sound waves in a rock

• body waves: travel through the (body of) earth

  • p-waves

  • s-waves

• surface waves: travel near surface only

  • love waves

  • Rayleigh waves

Body Waves

• travel through (body of) earth

• faster than surface waves

• generally not damaging to buildings

• can travel across/around the earth

• 2 types: p and s waves

P-Waves

• p = primary (or pressure)

• fastest, they arrive first\

• wave motion: parallel to direction of wave propagation

S-Waves

• s = secondary (or shear)

• slower than P-waves, but still much faster than surface waves

• wave motion: perpendicular to direction of wave propagation

Surface Waves

• travel near the surface only

• slower than body waves

• carry energy for greater distances away from the epicenter

• very damaging to buildings

• 2 types: love an Rayleigh waves

Love Waves

• first described by british mathematician A.E.H Love

• much slower than body waves

• move side to side, perpendicular to direction of wave propagation

Rayleigh Waves

• predicted to exist by Lord Rayleigh

• much slower than body waves

• move backwards- rotating, elliptical motion