Seismic waves are waves of energy caused by earthquakes or explosions that travel through the earth or along its surface. There are two main types of seismic waves - body waves that travel through the earth's interior and surface waves that travel along the surface. P-waves are the fastest body waves and arrive first, followed by S-waves. Rayleigh waves are the most destructive surface waves and cause most earthquake shaking by rolling along the ground up and down and side to side. Observations of seismic wave speeds through the earth indicate that its interior consists of a solid rocky lithosphere and mantle, with liquid outer core and solid inner core.

2. SEISMIC WAVE

3. LISTEN !!

4. Earthquake
▪An Earthquake occurs when energy is
released through rapid movement along
a fault.
▪Energy from an Earthquake is carried
away from the focus as Seismic Wave

5. Seismic Wave
▪These are waves of energy caused by the
sudden breaking of rock within the earth or
an explosion.
▪They can be distinguished:
Where they move – Earth’s interior vs surface
How they move – vertically vs. horizontally
How fast they move – meters per second

6. Body Wave
▪ refer to the
vibrations that travel
through the interior
of the earth.
▪ refer to vibrations that travel at
the surface of the earth.
▪ Easily distinguished by a
seismogram
▪ These are the most responsible
for the damage and destruction
associated with earthquake.
Main Types of Seismic Wave
Surface Wave

7. P – waves
(primary waves)
▪ The fastest kind of seismic wave,
and consequently the first to
arrive at a seismic station.
▪ Can move trough solid and fluid
like water or the liquid layers of
the earth.
▪ It pushes and pulls the rock it
moves through.
▪ Slower than a P wave
▪ S waves displace rocks at right angles
to the direction they are travelling.
▪ Can only move through solid rock and
not in liquid.
▪ They move rock particles up and down
or side-to-side perpendicular to the
direction that the wave is travelling.
Types of Body Wave
S – waves
(secondary waves)

8. P – waves
(primary waves)
▪ P waves are compressional waves.
▪ The energy travels in the same
direction as the wave travels.
▪ S waves are transverse waves.
▪ Another term is shear waves.
▪ The energy is perpendicular to
the direction of wave travel.
Types of Body Wave
S – waves
(secondary waves)

9. P – waves
(primary waves)
▪ The property of S wave in
which it cannot travel trough
liquid led seismologists to
conclude that the outer core is
a liquid.
Types of Body Wave
S – waves
(secondary waves)

10. WATCH !!

11. L – waves
(Love wave)
▪ Named after A.E.H. Love a British
mathematician who worked out
the mathematical model for this
kind of model.
▪ It’s the fastest surface wave and
moves the ground from side-to-
side.
▪ It produce entirely horizontally
motion.
▪ Named for JohnWilliam Strutt, Lord
Rayleigh who mathematically
predicted the existence of this kind of
wave in 1885.
▪ Rolls along the ground just like a wave
rolls across the ocean
▪ It moves the ground up and down,
side-to-side in the same direction that
the wave is moving.
Types of Surface Wave
Rayleigh Wave

12. ▪ Most of the shaking felt from an
earthquake is due to the Rayleigh wave
, which can be much larger than the
other waves.
Types of Surface Wave
Rayleigh Wave

15.  Seismic waves travel fast through this rocky sphere. Below the
lithosphere, the seismic waves slow down.
 This observation indicates a very high temperature that melts
rocks, making the molten behave like a fluid.
 Scientists call this region of the mantle asthenosphere.
 Below the asthenosphere, seismic waves travel fast again
indicating that the lower part of the mantle is solid.
 It is probably the very high pressure that keeps it solid in spite of
the high temperature.

16.  A similar phenomenon is observed in the core.
 Seismic waves travel slowly through the outer core
indicating that it is molten due to the extremely high
temperature.
 Then again the inner core is solid in spite of the very high
temperature.
 Most probably, the very high pressure in the deepest part
of the earth keeps it solid.

17. 1. The fastest type of seismic wave and arrive at a seismic station first.
2. Arrive at a seismic station second.
3. It is the fastest surface wave and moves the ground from side-to-side.
4. Refer to the vibrations that travel through the interior of the earth.
5. refer to vibrations that travel at the surface of the earth.
6. Can move through solid and fluid like water or the liquid layers of the earth.
7. Can only move through solid rock and not in liquid.
8. This type of wave is also known as compressional wave.
9. the most responsible for the damage and destruction associated with
earthquake.
10. Also known as the shearing wave.
QUIZ 2

18. 1. P-WAVE / PRIMARYWAVE
2. S-WAVE / SECONDARYWAVE
3. L-WAVE / LOVEWAVE
4. BODYWAVE
5. SURFACEWAVE
6. P-WAVE / PRIMARYWAVE
7. S-WAVE / SECONDARYWAVE
8. P-WAVE / PRIMARYWAVE
9. RAYLEIGHWAVE
10. S-WAVE / SECONDARYWAVE
QUIZ 2 - ANSWERS

19. QUIZ 2

21. Add a SlideTitle - 5