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You know
What?
What is the
Earthquake ?

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Welcome to Our Presentation

Presentation
On
Earthquake ,Cause ,Consequence ,Characteristic and
Earthquake Zone
This Presentation is Under :
Course : Geomorphology – I
Course Code : GES 1201
Course Instructor : Biddut Kumar Ghosh
Lecturer in Geography and Environment
Science
Begum Rokeya University ,Rangpur

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CONTENT
• Introduction
• Concept of earthquake
• Elements
• Types
• Characteristics
• Causes
• World distribution
• Earthquake in Bangladesh
• Effect
• Advantage
• Disadvantage
• Conclusion

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How Earthquakes Start?
Earthquakes start the moment rocks begin to scrape past each other along
a fault.

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Earthquakes Wave
Seismic Waves
Two types:
Body waves Surface waves
PWave S Wave R Wave LWave

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Body Wave is mainly two
types.
P Wave ( Primary Wave )
S Wave ( Secondary Wave )
Body waves travel through the interior of the
earth .

Surface Waves
Rayleigh Waves and Love Waves
Travel just below or along the ground’s surface
Slower than body waves; rolling and side-to-side
movement
Especially damaging to buildings

Cause of Earthquake
Volcanism Faulting Plate Movement Anthropogenic Cause

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Volcanism
Earthquakes related to volcanic
activity may produce hazards
which include ground cracks,
ground deformation, and
damage to manmade structures.
When the magma release ,it
release energy .Thus the energy
cause earthquake because it
creates vibration

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Plate Movement
Elastic Rebound Theory
Rocks bend under stress
while storing elastic energy.
When the strain in the rocks
exceeds their strength,
breaking will
occur along the fault.
Stored elastic energy is
released as the earthquake.
Rocks "snap back”, or
rebound to their original
condition.

Faults
• 1. Normal Fault:
– Produced at divergent
boundaries
– Rocks above the fault
surface move down
• 2. Reverse Fault:
– Produced at convergent
boundaries
– Rocks above the fault
move upward
• 3. Strike Slip Fault
– Produced at transform
boundaries
– Rocks slide past each other in
different directions
Normal Fault
Reverse Fault
Strike Fault
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Anthropogenic Cause
 Irrigation
 Deforestation
 Mining
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The Seismogram
The device which records
Earth tremors
A pendulum swings when
the earth moves
The pen attached to the
pendulum records the
movement
https://youtu.be/Gbd1FcuLJLQ

The Richter Scale
Measures earthquake magnitude.
Based on the amplitude of the wave produced on the
Seismograph.

Characteristic of Earthquake
o It is a matter of frightened.
o It shakes for long distance.
o It is happened along the edge of the
tectonic plate. The plate move and push
against each other.
o Something snaps at the weakest point
along a fault line.
o Big shocks waves go out from the
focus where the shock waves start.
o The epicenter is on the surface right
above the focus.
o It is very destructive natural
phenomena.
o It maybe happened 50-100 km benith
the earth surface .
o Same iso-seismic line covered area is
called iso-seismic region.

• Red dots are
shallow
• Green are
intermediate depth
• Blue and purple
are deep
Major Earthquakes Zone in the World

Earthquakes Zone in Bangladesh
The Zone-II includes the
greater districts of
Dinajpur, Bogra, Dhaka
and Chittagong and the
shocks of intensity of VIII
are possible. The
southern part of the
country, the least active
region, where the
maximum intensity is not
likely to exceed VII, is in
the Zone-III. The experts
suggest not to construct
normal buildings with
more than 60m height.

Consequence of Earthquake
Damage to man-made structures: Damage to man-made structures, such as roads,
bridges, dams and buildings from ground motion.
Image by H.G. Wilshire, U.S. Geological Survey.

Ground Rupture: Ground rupture is another important effect of earthquakes which occurs
when the earthquake movement along a fault actually breaks the Earth's surface

Riverbed Change:

Sea Level Rise:

Fire: Fires, often associated with broken electrical and gas lines, is one of the
common side effects of earthquakes. Gas is set free as gas lines are broken
and a spark will start bringing "inferno". To complicate things water lines are
broken and so there is no water to extinguish the fire.

Tsunami:

Advantage of earthquake
 Earthquake waves are helpful in knowing about the interior of the earth.
 Landslides caused by earthquake help in weathering of rocks.
 Folds, Thrust, Faults etc. caused by earthquakes lead to the formation of new land
formations.
 Due to subsidence in sea bottom deep gulfs are formed which give birth to good sea
ports.
 Sometimes vast area comes out of sea as a result of elevation.
 New minerals areas are uncovered or are raised up.
 Rivers adopt new courses which provide new agricultural land.

Disadvantages of earthquake:
 Earthquake bring about large scale destruction of life and property.
 Earthquake destruction buildings and also destroyed roads, railways and bridges.
 Sometimes earthquake dam the rivers are obstructed by the natural flow of water.
 When the earthquake occurs in the sea, it causes strong waves in the sea which results in
heavy damage to ships.
 Earthquakes are responsible for big faults, folds.
 Under ground water also causes by earthquake.
 Fires break out due to earthquakes.

Conclusion:
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It is evident from the above that we are facing a great challenge to adequately manage a
major earthquake which may happen anytime in Bangladesh's minimize suffering of the people,
loss of properties and major casualties the government, media, doctors, engineers, lawyers
peoples representatives and mass media and all level of people should come forward with strong
voice to Formulate a central body to monitor this disaster, buy necessary equipments to cope,
arrange establishment of multidisciplinary hospitals in the danger zone immediately. Also mass
awareness among the general people regarding earthquake, not to get panic.

Reference
(1)http://en.wikipedia. Org/wiki/Earthquake.
(2)www.thaindian/bangladesh face high risk of earthquake
(3)www.consmos.org/projects/SAFER_cities Bangladesh
(4)www.apsco.int/(26)Suraiya_Begum Earthquake
(5)http//geocities.com/bdeqsoc/
(6)www.log Bangladesh.org/DER/earthquake

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