Re: What are the three types of earthquake waves?

Dear Anna,

Broadly speaking, there are two types of earthquake waves, namely body 
waves and surface waves.  Body waves are waves that travel through the 
Earth’s interior.  Surface waves are waves that travel close to the 
Earth’s surface, like waves on a lake.

There are two types of body waves, namely P-waves and S-waves.  They are 
as follows:

P-waves.  P-waves are sometimes called pressure waves, and sometimes they 
are called longitudinal waves.  P-waves are transmitted through the 
Earth’s interior with a backwards and forwards motion along the line of 
travel, by alternating compression and dilatation.  A jack hammer creates 
P-waves.  They are capable of passing through any type of material they 
encounter, including the liquid of the Earth’s outer core, although they 
will be bent and deflected when they pass across the boundaries separating 
layers of different densities.

S-waves.  S-waves are also called transverse waves.  They travel  with a 
side-to-side or up and down motion, or a combination of the two, in which 
the particles in the medium through which the wave is passing move at 
right angles to the direction in which the wave is travelling.  A good 
analogy is the wave motion that occurs when you shake a rope or a curtain 
cord which is fixed at one end.  S-waves will not travel through liquid, 
so they are stopped when they reach the Earth’s liquid outer core.

There are also two types of surface waves, namely Love waves and Rayleigh 
waves.  They are as follows:

Love waves.  Also called L-waves, these are rather like horizontal S-
waves, but with the difference that the amplitude of the wave diminishes 
rapidly with increasing depth, so that they can only travel long distances 
close to the Earth’s surface.

Rayleigh waves.  Rayleigh waves are similar to ocean waves, in that the 
motion of each particle in the medium through which the wave travels 
describes an ellipse as the wave passes, and the amplitude of the wave 
decreases with increasing depth.  Therefore, Rayleigh waves also travel 
long distances only near to the Earth’s surface.

I hope this answers your question.

Best wishes,

David Scarboro