What Is Seismology?
Seismology is the study of earthquakes and
seismic waves that move through and around
the earth. A seismologist is a scientist who
studies earthquakes and seismic waves.
What Are Seismic Waves?
the waves of energy caused by
the sudden breaking of rock
within the earth or an explosion
Characteristics of seismic waves
. The composition of the material through which P waves
and S waves travel affects the speed and direction of
the waves.
The change in speed and direction is how scientists
concluded the different layers had different physical
properties.
For example, P waves travel fastest through materials
that are very rigid and are not easily compressed. By
studying the speed and direction of seismic waves,
scientists can learn more about the makeup and
structure of Earth’s interior.
Types of Seismic Waves
Body waves-
Surface waves-
Body waves can travel
through the Earth's
interior
Surface waves can only
travel along the surface
of the Earth
Higher frequency than
surface waves
Body Waves
P-wave (primary, compression)




First to arrive
Can move through solid and
liquid
particles move in the same
direction that the wave is
moving in, which is the
direction that the energy is
traveling in, and is sometimes
called the 'direction of wave
propagation'.
Push and Pull
S-wave (secondary, transversal)
Arrives second (slower than Pwaves)
Can only move through solid (this
is how scientists discovered
the outer core was liquid)
S waves move rock particles up
and down, or side-to-side-perpendicular to the direction
that the wave is traveling in
(the direction of wave
propagation).
P- Waves
S- Waves
Comparison of waves p. 321 in textbook
Direction of the wave
Speed and Direction of Waves
P waves can travel through all of the layers, the speed
and direction of the waves change as the waves pass
through each of Earth’s layers. The waves bend in
such a way that P-wave shadow zones form.
S waves cannot pass through the liquid outer core
creating an even larger S-wave shadow zone.
Surface waves
Love waves



Travels along the
Earth's surface
Rayleigh Waves
Travels along the Earth's
surface
Rolls along the ground like
a wave rolls along the
Moves in a side to side ocean
direction
Fastest surface wave
Shadow
zones
.
A shadow zone is
an area on the
Earth's surface
where no direct
seismic waves from
a particular
earthquake can be
detected
P- waves
S-waves