When an earthquake occurs, energy is released in the form of seismic waves that travel through the Earth. There are two types of seismic waves: body waves and surface waves. Body waves travel through the interior of the Earth and include P waves and S waves. P waves are the fastest seismic waves while S waves move more slowly and can only pass through solids. Surface waves travel along the top of the Earth's crust and cause more damage than body waves.

1. Lesson 2: Earthquakes
When an earthquake occurs, a lot of energy is given off. This energy
travels through the Earth in the form of waves called seismic waves.
There are two kinds of seismic waves.
• Body waves are seismic waves that travel through the inside of
Earth to the surface.
• Surface waves are seismic waves that travel through the top part
of Earth’s crust.
There are two kinds of BODY WAVES: P waves and S
waves

2. Lesson 2: Earthquakes
There are two kinds of BODY WAVES: P waves and S
waves
Primary waves (also called pressure
waves or P waves) are the fastest kind of
seismic waves, traveling at 1 to 5 miles per
second (1.6 to 8 kilometers per second).
They can pass through solids, liquids and
gases easily. As they travel through rock, the
waves move tiny rock particles back and
forth -- pushing them apart and then back
together -- in line with the direction the wave
is traveling. These waves typically arrive at
the surface as an abrupt thud.

3. Lesson 2: Earthquakes
There are two kinds of BODY WAVES: P waves and S
waves
Secondary waves (also called shear waves, or
S waves) are another type of body wave. They
move a little more slowly than P waves, and can
only pass through solids. As S waves move, they
displace rock particles outward, pushing them
perpendicular to the path of the waves. This
results in the first period of rolling associated
with earthquakes. Unlike P waves, S waves
don't move straight through the earth. They only
travel through solid material, and so are stopped
at the liquid layer in the Earth's core.

4. Lesson 2: Earthquakes
There are two kinds of Seismic WAVES: Body waves and
Surface waves
Surface waves travel along the top of
Earth’s crust. Only the very top part of the
crust moves when a surface wave
passes. Surface waves travel much more
slowly than body waves. When an
earthquake happens, surface waves are
the last waves to be felt. Surface waves
cause a lot more damage to buildings and
landforms than body waves do.
READ: Table 1. PHIVOLCS Earthquake Intensity Scale (PEIS) page 12-13

5. Lesson 2: Earthquakes
There are two kinds of Surface
waves:
• L wave (Love wave)
• R wave (Rayleigh wave)
READ: Table 1. PHIVOLCS Earthquake Intensity Scale (PEIS) page 12-13