The Earth's Interior

1. MODULE2
EARTH AND SPACE

2. EARTHQUA
KE
- is a vibration of the Earth produced by the rapid release
of energy most often because of the slippage along the fault
in the Earth’s crust

3. SEISMIC WAVES
- the energy that radiates in all directions from the focus
in form of waves
- this waves are recorded in a SEISMOGRAPH
Two Main Types of Seismic Waves
• body wave
• surface wave

4. SURFACE WAVE
- Can only travel through the surface of the Earth
- They arrive after the main P and S waves and confined
to the layers of the Earth
Two Types of Surface Wave
• Love Waves
• Rayleigh Waves

5. LOVE WAVE
- Was named after Augustus Edward Hough Love, A
British mathematician who worked out for the
mathematical model for this kind of wave in 1911.
- It is FASTER than Rayleigh wave
- It moves the ground in a side-to-side horizontal motion,
like that of a snake’s causing the ground to shake
- Can cause most damage to structures

6. RAYLEIGH
WAVE
- Was named after John William Strutt, “Lord Rayleigh”,
mathematically predicted the existence of tis kind of
wave in 1885.
- It rolls along the ground just like wave rolls across a
lake or an ocean
- Most of the shaking felt from an earthquake

7. BODY WAVE
- Body waves can travel through the Earth’s inner layers
- These waves are of higher frequency than surface waves
Two Types of Body Wave
• P-Waves (Primary Waves)
• S-Waves (Secondary Waves)

8. P-WAVES
- or Primary Waves or Compressional Wave
- Travel by particles vibrating parallel to the direction of
wave
- Travels faster than the S-wave, it reaches the detector
first
- They travel through solids, liquids and gases

9. S-WAVES
- or Secondary Wave or Shear Wave
- Moves as shear or transverse waves, and force he
ground to sway from side to side, in rolling motion that
shakes the ground and forth perpendicular to the
direction of the waves
- Cannot travel through any liquid

11. - In 1909, Yugoslavian
seismologist ANDRIJA
MOHOROVICIC found out that
the velocity of seismic waves
changes and increases at a
distance of about 50 kilometers
below the earths surface.
- The boundary between the
crust and mantle is called
Mohorovicic Discontinuity or
“Moho”
1909

12. - BENO GUTENBURG, A
German seismologist, the
existence of a shadow zone,
could only be explained if the
Earth contained a core
composed of a material
different from that of the
mantle causing the bending of
the P-waves.
- The mantle-core boundary is
called Gutenberg Discontinuity

13. - The innermost layer of
the Earth was predicted
by INGE LEHMANN, A
Danish Seismologist,
discovered a new region
of seismic reflection
within the core.
1936

14. - The size of the inner core was accurately calculated
through nuclear underground tests conducted in
Nevada, USA. Echoes from seismic waves provided
accurate data in determining its size.

16. Thickness of the Different Layers of the Earth
LAYER THICKNESS (km)
Crust 40
Mantle 2900
Outer Core 2200
Inner Core 1278

17. Activity1: GRAPHIC ORGANIZER
Objectives:
The following activity will make the learners differentiate the types
and understand the characteristics of seismic waves. It will prepare them in
learning the properties and composition of the different layers of the Earth.
Materials:
1. Manila Paper
2. Markers
3. Scotch Tape
Procedure:
1. Using the graphic organizer, write necessary information to complete the
seismic waves

18. Guide Questions:
Q1. Differentiate surface waves from body waves.
Q2. Which type of wave do you think were useful to seismologists in
their study of the Earth’s interior? Explain your answer.

20. Guide Questions:
Q1. Differentiate surface waves from body waves.
Surface waves travel only on the Earth’s surface like ripples of water
while body waves travel through the Earth’s body (interior). In
addition, surface waves arrive last at seismic recording stations
compared to the body waves.
Q2. Which type of wave do you think were useful to seismologists in
their study of the Earth’s interior? Explain your answer.
The body waves were used by seismologists because they can pass
through the Earth’s interior.

21. Thank you!!