EARTHQUAKE
Presented by
Niveditha Nethaji
Grade -8A

 Earthquakes are the shaking, rolling or sudden shock of
the earth’s surface.
 They are the Earth's natural means of releasing stress.
 Earthquakes usually last less than one minute.
 Earthquakes cannot be predicted.
What is an earthquake?

 There are about 20 plates along the surface of the
earth.
 The plates are all moving in different directions and
at different speeds.
 The plates crash together, pull apart or sideswipe each
other commonly results in earthquakes.
What causes an earthquake?

Primary Wave (P-Wave)
 Fastest
 first waves to arrive.
Secondary Wave (S-Wave)
 second fastest (~60%)
 Move up and down
 Travel slow
Types of Earthquake waves

 It compresses and expands the ground.
 Travels around 8km/second.
 Travels through liquids and solids.
 You may feel earthquake.
Primary Wave (P-Wave)

 It moves the ground up and down or side to
side.
 Travels around 4.5km/second.
 Travels through solids.
 Usually cause more damage.
Secondary Wave (S-Wave)

 Primary Wave (P-Wave)
Which wave is faster?

 P wave can move through solid rock and
fluids, like water or the liquid layers of the
earth.
 P-waves are compression waves that apply a
force in the direction of propagation. ... The
energy is thus less easily transmitted through
the medium
Why P waves are faster than
S waves?

 A longitudinal wave is a wave in which
particles of the medium move in a direction
parallel to the direction that the wave moves.
 This means that the particles move left and
right.
What is a longitudinal wave?

 sound waves.
 ultrasound waves.
 seismic P-waves.
What are examples of
longitudinal waves?

 Transverse waves are always characterized by
particle motion being perpendicular
to wave motion.
 Ripples on the surface of water.
Transverse waves

 Vibrations in a guitar string.
 Electromagnetic waves
Example- Light waves, microwaves, radio
waves.
 Seismic S-waves.
What are examples of
Transverse waves?