unstable movement of ground is known as earthquake . Earthquake is transferred by waves known as Primary waves and secondary waves. Effect of earthquake includes faults. There are three types of faults caused by earthquake .

1. EARTHQUAKE &
FAULTS

2. What We Are Going To Learn
• What is mean earthquake ?
• Elastic rebound theory.
• Earthquake intensity measurement
• Earthquakes waves
• Types of faults

3. Earthquake
• Shaking and vibration of the Earth’s crust due to
plate tectonics (movement of plates)
• Happen along any type of plate boundary. They
also occur along faults which are large cracks in the
earth’s crust. Most faults are associated with large
plate boundaries where violent earthquakes usually
occur.

5. Elastic rebound theory
• Rocks bend until the strength of the
rock is exceeded
• Rupture occurs and the rocks quickly
rebound to an unreformed shape
• Energy is released in waves that radiate
outward from the fault

7. Measuring Earthquake

8. • The power (magnitude) of an earthquake is
measured on the Richter scale, using an instrument
called a seismometer.
• The Richter scale is numbered 0-10 with 10 being
the most powerful.
• The Richter scale is logarithmic – an earthquake
measuring 7 is 10 times more powerful than one
measuring 6 and 100 times more powerful than one
measuring 5. Up until 2 on the Richter Scale only
instruments will detect the earthquake. Earthquakes
above 6 cause serious damage and sometimes many
deaths

9. • The Mercalli scale measures the damage caused
by an earthquake.
• The Mercalli scale goes from I to XII e.g. “VI.
Everyone feels movement. People have trouble
walking. Objects fall from shelves. Pictures fall
off walls. Furniture moves. Plaster in walls might
crack. Trees and bushes shake. Damage is slight
in poorly built buildings. No structural damage.”

10. Seismic Waves
• Response of material to the arrival
of energy fronts released by rupture
• Two types:
• Body waves
P and S
• Surface waves
R and L

11. Body Waves: P and S waves
P or primary waves
• Fastest waves
• Travel through solids, liquids, or gases
• Compressional wave, material movement
is in the same direction as wave movement
S or secondary waves
• Slower than P waves
• Travel through solids only
• Shear waves - move material perpendicular
to wave movement

13. Surface Waves: R and L waves
• Travel just below or along the ground’s
surface
• Slower than body waves; rolling and side-
to-side movement
• Especially damaging to buildings

15. Faults
• A crack or facture in earth crust along which
rock on one side has moved relative to rock
on other side.
• Caused due to earthquake
• Three types :
Transverse fault
Normal fault
Reverse fault

16. Transverse fault
Land Plates
forces on the land
This is a Strike Slip
Fault
or a Transverse Fault
San Andréa Fault

17. Transverse fault
Imperial Valley, California, Earthquake (Magnitude 6.5)
October 15, 1979

18. Normal fault
Also called
Scarp face

19. Normal fault
Government Hill School, March 27, 1964 Magnitude 9.2
Anchorage, Alaska

20. Reverse Fault

21. This Presentation is Brought to you
by
An Civil Engineering Blog