The document discusses earthquakes, including their causes, types, effects, and measurement. Earthquakes are caused by the sudden release of stress along faults within the earth's crust. They can be shallow, mid-focus, or deep, and cause both primary (P) waves and secondary (S) waves. The magnitude and intensity of quakes are measured using the Richter scale and Mercalli scale, respectively. Major quakes frequently occur at plate boundaries and have caused widespread damage throughout history.

1. EARTHQUAKES
Causes & Consequences
By Nida Shahzad

2.  Earthquakes
 Types of Earthquakes
 Anatomy of Earthquakes
 Causes of Earthquakes
 Waves of Earthquakes
 Seismograph & Richter Scale
 Distribution of Earthquakes
 World Deadliest Earthquakes
 Earthquakes in Pakistan
 Effects of Earthquakes
Contents

3.  It is the release of Internal Stress of Lithosphere
 Shaking of Earth Crust
 Earthquakes are also termed as Creep, Seismic Slip or it
may be Elastic Rebound depending upon the nature of
Movement
Earthquakes

4.  With the sudden displacement and associated stress
release, the rocks snap back elastically to their previous
dimensions, this behavior is called Elastic Rebound.
Elastic Rebound

5.  When movement along fault occur gradually and
smoothly it is called Creep
 It is also called Seismic Slip
Seismic Slip

6.  Generally there are following types of Earthquakes depending
upon their depth
a. Shallow Focus Earthquakes <70km
b. Mid Focus Earthquakes 70-300km
c. Deep Focus Earthquakes 300- upto 700km
 On the basis of Magnitude Earthquakes can be classify as
a. Micro-Earthquakes
b. Macro-Earthquakes
Types of Earthquakes

7.  Foreshocks
 Epicenter
 Hypocenter/Focus
 After Shocks
 Magnitude
a. Richter Scale
 Intensity
a. Mercalli Intensity Scale
Anatomy of Earthquakes

8.  Earthquakes are generally occurs due to the Plate
Movements or due to the Faults
 90 percent of the world's earthquakes occur along plate
boundaries
 The rocks are usually weaker and yield more readily to
stress
Causes of Earthquakes

9.  Convergent Plate Boundaries
 Divergent Plate Boundaries
 Transform Plate Boundaries
Plate Boundaries

11. Faults
 Fault is a fracture or zone of fractures between two
blocks of rock
 Faults allow the blocks to move relative to each other
 This movement may occur rapidly, in the form of an
earthquake - or may occur slowly, in the form of creep
 Faults may range in length from a few millimeters to
thousands of kilometers.
 Normal Fault (Vertical Displacement due to Tension)
 Fault Scrap (Steep, Straight Cliff like Feature)
 Reverse and Overthrust Faults

12.  There are 3 basic types of faults
1. Dip-Slip Fault
2. Strike-Slip Fault
3. Oblique-Slip Fault
Types of Faults

14.  1. Dip-slip faults are inclined fractures where the blocks
have mostly shifted vertically. If the rock mass above an
inclined fault moves down, the fault is termed normal,
whereas if the rock above the fault moves up, the fault is
termed reverse.
 A thrust fault is a reverse fault with a dip of 45 degrees or
less. Oblique-slip faults have significant components of
different slip styles.
 2. Strike-slip faults are vertical (or nearly vertical) fractures
where the blocks have mostly moved horizontally. If the
block opposite an observer looking across the fault moves
to the right, the slip style is termed right lateral; if the block
moves to the left, the motion is termed left lateral.

15.  Seismic energy travels through the crust in the form of
waves
 The propagation velocity of seismic waves depends
upon the density and elasticity of the medium in which
seismic waves are penetrated
 Seismic Waves are of two types
a) Body Waves
b) Surface Waves
Waves of Earthquakes

16.  A body wave is a seismic wave that moves through the
interior of the earth
 P and S waves are Body Waves
 Each type of wave shakes the ground in different ways
Body Waves

17.  P-Waves can travel through gases, solids and liquids
 P-waves are produced by earthquakes and recorded
by seismometers
 The name P-wave stands either for Primary Wave
 P-Waves has the highest velocity and is therefore the
first to be recorded
 It is a longitudinal wave and motion is parallel to
direction of propagation
P-Waves

18.  Like P-Waves they are high frequency, short-wavelength
waves
 But instead of being longitudinal they are transverse
 On the surface of the Earth, S-Waves are responsible for
the sideways displacement
 S-waves move like waves in a rope
S-Waves

19.  Travel near the surface
 Surface Waves are of following types
 Rayleigh Waves
 Love Waves
 The combination of Rayleigh and Love Waves results in
ground heave and swaying buildings
 Surface waves cause the most devastating damage to
buildings, bridges, and highways
Surface Waves

20.  These instruments are used to measure the magnitude of
the Earthquake
 The seismograph consists of a seismometer (the
detector) and a recording device
 Richter Scale was developed by Charles F.Richter in
1935
 It measures the magnitude of the earthquakes
Seismograph & Richter Scale

21.  90 percent of the world's earthquakes occur along plate
boundaries
 47% of major earthquakes occur within 100 miles of a
convergent plate boundary
 71% of major earthquakes occur within 200 miles of a
convergent plate boundary
Distribution of Earthquakes

22. 1. Shensi, China, Jan. 23, 1556
2. Tangshan, China, July 27, 1976
3. Aleppo, Syria, Aug. 9, 1138
4. Sumatra, Indonesia, Dec. 26, 2004
5. Haiti, Jan 12, 2010
6. Damghan, Iran, Dec. 22, 856
7. Haiyuan, Ningxia , China, Dec. 16, 1920
8. Ardabil, Iran, March. 23, 893
9. Kanto, Japan, Sept. 1, 1923
10. Ashgabat, Turkmenistan, Oct. 5, 1948
World Deadliest Earthquakes

23. 1. Quetta 1935
2. Pasni 1945
3. Gilgit, Hazra and Sawat Valley 1974
4. Muzaffarabad 2005
5. Baluchistan 2008
Earthquakes in Pakistan